Patent Application
20180066358
The present invention relates to methods and apparatus for performing the combinatorial synthesis of carbon tetracarbide and diamond mass therefrom. mass therefrom.
More particularly, the present invention relates to methods and apparatus for controllably producing carbon tetracarbide having the a tetrahedral structure containing five carbon atoms with four apical carbons and one center (“cage position”) carbon with precise stoichiometry, and three-dimensional diamond mass structures based thereon.
The present invention also relates to products fabricated from the diamond produced.
Current methods for producing man-made diamond entail producing diamond either by chemical vapor deposition (CVD) or high pressure/high temperature (HPHT) methods. CVD methods of fabricating diamond are derived from the physical methods and equipment used by the semiconductor industry. But, adapting similar or existing equipment and infrastructure does not necessarily lead to the most efficient and effective means of producing diamond films. CVD methods are inefficient because they rely on high temperature conditions and surface kinetics to assemble carbon atoms into diamond or diamond-like materials. This relies on atomic motion, which is chaotic and unpredictable. The original conception of HPHT methods for making diamond was based on the brute force approach of emulating the geological processes by which diamond is produced in nature. But, nature doesn't typically produce pure diamond, much less pure diamond films that can be fabricated into industrially or commercially. Thus, current physical methods for producing diamond are inefficient and costly because they depend on surface kinetics and/or extreme process conditions for the production of diamond, and do not provide a thermodynamically driven synthesis that could favor the specific production of carbon tetracarbide. Further, current methods of producing diamond also tend to be inefficient and uneconomical because they require many hours, if not days, to produce diamond films sufficiently thick to be of any practical use.
Moreover, diamond produced by current and conventional methods is typically impure, which prevents its use in many potential applications. To improve the purity of conventionally made diamond, additional processes and steps (for example, high temperature annealing), are required which is costly in terms of time and money, often making such diamond products economically unfeasible for most applications. A further limitation is that many substrate materials upon which diamond could be deposited are precluded from use because they are incompatible with the extreme conditions typically required by conventional diamond-forming methods, such as high temperatures and pressures.
Current methods of diamond production are also limited because diamond deposition on a substrate cannot be location on a substrate. These conventional methods typically are limited because they produce films that are essentially “sheets” of diamond that form at random in a deposition space. Thus, current methods do not disclose or enable deposition of diamond at a predetermined location or locations on a portion of, or in relation to, a substrate either at a planar position of the substrate or vertically upon a previously deposited diamond mass. Thus, conventional methods can neither provide for a controllable deposition of diamond mass three-dimensionally nor can they controllably deposit a diamond mass three-dimensionally to produce predetermined, complex shapes. Furthermore, current methods do not disclose a controlled delivery of reactants for the combinatorial synthesis of carbon tetracarbide such that a diamond mass can be controllably formed to produce a predetermined three-dimensional shape at a predetermined location. In particular, they do not disclose the controlled delivery of reactants by the use of a dispenser that targets a predetermined location for deposition. They also neither disclose nor enable controlling the deposition of diamond by starting, stopping, and re-starting the diamond deposition process as a means of controlling product morphology. Indeed, given the relatively long time necessary for conventional methods to deposit diamond on a substrate, this would be counterintuitive and counterproductive.
Current methods for producing diamond cannot be easily adapted to the requirements and demands of widely differing applications nor can they be implemented using different apparati that are specifically designed to efficiently produce diamond-based products for specific uses. Current methods that use CVD to produce diamond films cannot produce them efficiently or quickly, and methods that rely on HPHT approaches cannot produce bulk diamond in large quantities or in a great variety of complex shapes. In fact, no current method for producing diamond enables the production of diamond of predetermined size and/or complex shape through the use of molds into which reactants are dispensed or injected. A representative sampling of current methods and their limitations are noted below.
An important difference between the combinatorial synthesis of the present Invention, which is thermodynamically driven, and chemical vapor deposition (CVD) processes is that CVD relies on surface kinetics. For example, Dodge, et al. disclose that “Being in the region where diamond is metastable compared to graphite, synthesis of diamond under CVD conditions is driven by surface kinetics and not by bulk thermodynamics.” (See US 2014/0234556, paragraph 3). CVD produces diamond by what is essentially best described as a physical process, while the synthesis of the present invention is an actual combinatorial chemical reaction. With CVD, diamond forms atom-by-atom on the surface of the deposition substrate. In the vapor phase reaction of the present invention, the chemical reaction, and, thus, diamond formation occurs in a reaction cloud adjacent to the deposition substrate. Because CVD diamond formation is difficult to control precisely, graphite and other impurities are an inevitable consequence of the process. In the present invention's synthesis, graphite does not enter into the equation at all because diamond is the only possible product of the reaction that can be deposited on the substrate. In fact, the tetrahedranoidal reactant molecules used in the combinatorial synthesis, such as benzvalene, are most of the way to constituting the diamond tetrahedron. In the combinatorial synthesis, carbon tetracarbide is formed when a tetrahedranoidal reactant molecule reacts with atomic carbon sourced from a carbon atom source such as cubane, and hydrogen atoms and a “leaving group” egress from the reaction chamber as effluent. Hence, it can be said that CVD produces impure diamond at the atomic scale where chaos reigns, while the chemical synthesis of the present invention produces diamond in an an orderly manner because the formation of carbon tetracarbide is formed with the addition of just one more carbon atom to the tetrahedranoidal reactant molecule, and then diamond mass is formed by crystallographic propagation of carbon tetracarbide units. Thus, the present combinatorial chemical synthesis provides for control of the fate of the reactants.
Dodge, et al. specify that “Atomic hydrogen is essential to the process because it selectively etches off non-diamond carbon from the substrate such that diamond growth can occur” (See US 2014/0234556, paragraph 4). The chemical synthesis of diamond mass in accordance with the present invention, by contrast, requires no etching and, indeed, minimizes the undesirable, contaminating presence of hydrogen by preferably using a carbon source (cubane) that has a one-to-one carbon to hydrogen content. Dodge, et al. further disclose that “If a suitable substrate is provided in close proximity to the plasma, reactive carbon containing radicals can diffuse from the plasma to the substrate and be deposited thereon. Atomic hydrogen can also diffuse from the plasma to the substrate and selectively etch off non-diamond carbon from the substrate such that the diamond growth can occur. (See US 2014/0234556, paragraph 7). Thus, carbon radicals and hydrogen are necessary for their CVD process, whereas, in the present invention's diamond synthesis, carbon radicals and hydrogen are to be avoided, and, at the very least, minimized as much as possible.
U.S. Pat. No. 4,849,199 discloses a method for suppressing the growth of graphite and other non-diamond carbon species during the formation of synthetic diamond. This method includes vaporizing graphite or other non-diamond carbon species with incident radiative energy that doesn't damage the substrate. Use of laser energy is also disclosed. This patent clearly evidences the major problem of contaminating graphitic impurities formed when using conventional diamond forming processes.
US 2014/0150713 discloses controlled doping of synthetic diamond material. During the disclosed diamond growth process using a CVD technique, dopant gases, including one or more of boron, silicon, sulphur, phosphorus, lithium and/or nitrogen are introduced into the plasma chamber. This patent describes that, in the region where diamond is metastable compared to graphite, synthesis of diamond under CVD conditions is driven by surface kinetics and not bulk thermodynamics.
Additionally, WO8802792 discloses a process for depositing layers of diamond and describes that the reaction to deposit graphite competes with that to deposit diamond, and under many conditions graphite rather than diamond is deposited. Once deposited, the diamond is energetically favored to convert to graphite, but the reverse reaction of conversion of graphite to diamond is not thermodynamically favored.
US 2011/0280790 discloses production of large, high purity single crystal CVD diamond. Their diamond is grown using a plasma assisted chemical vapor deposition technique at growth temperatures of about 1250° C. to 1350° C. with growth rates of up to 200 μm/hour.
U.S. RE41,189 discloses a method of making enhanced CVD diamond. In this method, CVD diamond is heated to temperatures between 1500° C. and 2900° C. at a pressure of 4.0 GPa to prevent significant graphitization and with some improvement in the optical properties of the diamond produced.
U.S. Pat. No. 5,284,709 discloses a two-stage, plasma CVD deposition process, and the detrimental effects of structural and chemical inhomogeneities on the phonon-mediated thermal conductivity of diamond. Thus, impure, structurally non-uniform diamond is not optimally effective as a heat transfer material.
U.S. Pat. No. 5,270,077 describes the production of diamond films on convex substrates while U.S. Pat. No. 5,776,246 discloses the production of diamond films on convex or concave substrates to compensate for stress and distortions in the diamond film that can cause cracking and other imperfections.
U.S. Pat. No. 5,507,987 discloses a method of making a freestanding diamond film with reduced bowing. The method entails depositing two different layers of diamond each at different deposition rates.
U.S. Pat. No. 6,319,439 discloses a method of synthesizing diamond film without cracks which entails the use of an artificially compressive stress while decreasing the deposition temperature in a step-wise fashion.
US 2014/0335274 discloses use of a mold to define the deposition of nano-diamond particles on a substrate. This is done merely to define the placement of a nano-diamond seed solution for subsequent formation of a diamond structure, which can be accomplished, as disclosed therein, according to methods for growing diamond on a diamond seed structure as known in the art.
U.S. Pat. No. 7,037,370 discloses freestanding diamond structures and methods. They produce a diamond layer “formed by chemical vapor deposition (CVD) over the surface of a substrate that has been fabricated to form a mold defining the subset of intersecting facets.” This patent also discloses the use of high temperature and high pressure methods.
U.S. Pat. No. 7,132,309 discloses semiconductor-on-diamond devices and methods of forming them wherein a mold is provided that has an interface surface configured to inversely match a configuration intended for the device surface of a diamond layer. However, only vapor deposition techniques for depositing diamond are disclosed and these techniques do not employ a chemical synthesis reaction that is thermodynamically driven to produce molecular diamond.
The diamond-based substrate for electronic devices, of U.S. Pat. No. 7,842,134, is grown by CVD on a silicon wafer.
Hence, in view of the many shortcomings of the conventional methods described above, a need remains for methods for producing diamond in a controllable manner without using diamond seeds or extreme reaction conditions of high temperature and high pressure. A need also continues to exist for methods of producing diamond that do not require one or more subsequent annealing steps to reduce impurities and imperfections in the diamond initially produced. A need also continues to exist for methods for producing diamond that allow for the controlled deposition of diamond mass in predetermined complex shapes.
Accordingly, it is an object of the present invention to provide methods for producing carbon tetracarbide and diamond mass without using high temperatures and high pressures.
Another object of the present invention is to produce a plurality of carbon tetracarbide units and a plurality of diamond masses.
Accordingly, it is an object of the present invention to provide a method for producing diamond, in a controllable way, using a combinatorial synthesis by forming carbon tetracarbide units each of which contains a tetrahedral structure having four apical carbon atoms and one carbon atom in the center of the tetrahedral carbon structure (unit cell).
It is also an object of the present invention to provide methods for producing carbon tetracarbide and diamond mass without using a diamond seed and without using any subsequent annealing step or steps to remove any impurities and/or imperfections.
It is, further, an object of the present invention to provide methods for producing carbon tetracarbide and diamond mass in a controllable manner to produce predetermined complex shapes of diamond mass.
Moreover, it is an object of the present invention to provide methods for producing carbon tetracarbide and diamond mass by combinatorial synthesis using controlled delivery of reactants, which allows for starting, stopping, and restarting the combinatorial synthesis as a means of controlling the morphology of the product diamond.
It is yet another object of the present invention to provide methods for producing carbon tetracarbide and diamond mass having no impurities, such as graphitic impurities, as measured by FT-IR reflectance spectroscopy. This eliminates the need for any costly subsequent process steps, such as annealing, to remove impurities in the product diamond.
It is still another object of the present invention to provide methods for producing carbon tetracarbide and diamond mass driven thermodynamically rather than kinetically.
It is yet another object of the present invention to provide methods for producing carbon tetracarbide and diamond mass at a growth rate limited only by the speed at which the reactants can be brought together.
Further, it is an object of the present invention to provide an apparatus for preparing, carbon tetracarbide and diamond mass.
It is yet an additional object of the present invention to use the combinatorial synthesis to provide a degree of control over the resulting diamond products so produced that has thus far been unobtainable by other methods.
Another object of the present invention is to provide a substrate upon which diamond is deposited wherein the substrate provides a three dimensional morphology, which, in combination with the deposited diamond, for specific applications, has improved properties for those applications that are determined by the structure of the diamond and the substrate surface interface.
It is yet a still further object of the present invention to combine diamond with at least one other material with dissimilar properties so as to produce a diamond-based composite whose characteristics are different from diamond and the other material or materials used in combination thereof.
It is yet still another object of the invention to provide an apparatus for implementing the combinatorial synthesis of diamond in the vapor phase.
It is yet another object of the invention to provide an apparatus for implementing the combinatorial synthesis, in the solid state, of diamond.
Another object of the invention is to provide an apparatus for implementing the combinatorial synthesis of diamond wherein the resulting diamond structure is of predetermined morphology.
Another object of the invention is to provide an apparatus for implementing the combinatorial synthesis of diamond wherein the apparatus includes sensors and actuators to monitor and manipulate, physical and chemical conditions within the apparatus and a control system operatively connected to the sensors and actuators to monitor and control the diamond production process.
U.S. Ser. No. 14/120,508, filed on May 28, 2014, now U.S. Pat. No. 9,061,917; and U.S. Ser. No. 13/204,218, now U.S. Pat. No. 8,778,295, are both incorporated herein by reference in their entirety.
Term Definitions
Carbon tetracarbide: means a molecular structure as exemplified by the two-dimensional drawing shown further below in this specification that ultimately leads to the production of diamond mass. In the present invention, carbon tetracarbide is produced by a combinatorial synthesis in reacting a tetrahedranoidal compound with a carbon atom. Carbon tetracarbide is formed in situ in this reaction. Carbon tetracarbide is the complex of the tetrahedranoidal compound and a single carbon atom inserted therein, which reacts with crystallographic propagation driven by internal energy to form a diamond mass. Carbon tetracarbide is constructed purely of five carbon atoms and has four carbon atoms at an apical position and one carbon atom inserted therein as shown herein. We also refer to carbon tetracarbide as the “diamond unit cell” as formed by the combinatorial synthesis even though this term is completely unrelated to any unit cell for diamond as is used in conventional crystallography. Carbon tetracarbide is also referred to herein as the “C5-building block” for diamond mass. As used herein, the term “diamond unit cell” always refers to an experimentally-determinable intermediate precursor to diamond mass, and is completely unrelated to the conventional crystallographic term “diamond unit cell” which is a theoretical construct, and not an experimentally-determinable existing chemical reactive intermediate. As used herein, the term “diamond unit cell” is synonymous with carbon tetracarbide, no more no less.
Crystallographic propagation: refers to the manner in which carbon tetracarbide driven by internal energy proceeds to form a diamond mass.
Diamond mass: means the resultant accumulation of diamond resulting from serial, continuous or concomitant depositions of carbon tetracarbide units to a surface, generally, or substrate, specifically, and formation from units of carbon tetracarbide by crystallographic propagation.
Carbon source: means a reactant that is a source of carbon atoms, such as cubane, for example, or an apparatus that produces carbon atoms.
Tetrahedranoidal compound: means any tetrahedranoidal compound having the ability to react with an active carbon atom to form the diamond unit cell carbon tetracarbide of the present invention. Non-limiting examples are benzvalene, dihydro-benzvalene, 3,4-diazabenzvalene and 2,3,4-methynylcyclobutanone (“tetrahedranone”). Of particular advantage are tetrahedranoidal compounds having ejection groups, such as —CH═CH— as in benzvalene, C2H4 as in dihydro-benzvalene, —CO— as in tetrahedranone and —N═N— as in 3,4-diazabenzvalene as shown in
Predetermined: means a design or shape determined previously to the actual production of carbon tetracarbide and diamond mass based upon a desired configuration suited for a particular use.
Combinatorial Synthesis: means the reaction of a tetrahedranoidal compound with a carbon atom to produce carbon tetracarbide.
Field measurements: as used herein means measurements of experimental variables, such as temperature, pressure, reactant flow rates, and nozzle sizes, for example, that may be adjusted with routine skill in the art to achieve best results in producing diamond mass and/or deposition of diamond mass on varying substrates or varying shapes.
Shapeable: means fabricable or shaped by deliberate design during the combinatorial synthesis reaction to produce carbon tetracarbide and then diamond mass. Thus, by virtue of the present invention carbon tetracarbide and diamond mass are depositable on substrates of varying shape, such as convex, concave, and ellipsoid as well as other three-dimensional shapes and of varying thickness as required for various end uses of the deposited diamond mass. Hence, this process is controllable to meet desired design specifications. Thus, for example, one exemplary definition of shapeable as used herein is to be rendered shapeable by a series of programmed deposition events as described in the present specification for a detailed description of
Inert gas or gases: means any one or combination of the noble gases, except radon. Thus, the term inert gas or gases includes helium, neon, argon, krypton and/or xenon. Generally, argon is used as it is less expensive than the other noble gases. This term includes neither nitrogen nor carbon dioxide, and necessarily precludes hydrogen for reasons already mentioned.
High energy discharge: means any high energy radiation produced by, for non-limiting examples, an electric arc, microwave generator, laser or RF plasma, for example. Any of these devices may be used to produce a high energy discharge to drive the combinatorial synthesis of diamond. Generally, for a microwave generator, power in the range of from about 0.5 kW to 3 kW at a frequency of from about 2 to 15 GHz is used. More preferably, 0.8 to 2 kW at a frequency of about 10-14 GHz is used. Often, power in the range of 1-2 kW at a frequency of 11-13 GHz is used. Time of exposure to the high energy discharge in order to drive both generation of atomic carbon and the combinatorial synthesis may be from 1 second to several minutes. For example, when conducting the combinatorial reaction in the solid state, about 5 to 10 seconds suffices to convert a homogenous solid mixture to diamond mass.
The range of suitable power and frequency ranges above for use of microwave generators may generalized as total energy applied, such that:
Total E applied=(Power×Frequency)/Time of Application
This formula may used to establish guidelines for use of other high energy discharges, such as electric arc, laser and RF plasma by considering total power applied irrespective of which type of high energy discharge is used.
With these guidelines, one of ordinary skill in the art can determine preferred total energy applied for using any particular tetrahedranoidal reactant and any type of high energy discharge.
Vacuum and Pressure: generally means a range of from about 0.5 atmospheres (vacuum) to about 2 atmospheres (pressure). Preferably, this ranges from about 0.75 to about 1.25 atmospheres. Most often, atmospheric pressure is used.
No Diamond Seed: means that the present invention uses no extrinsic or extraneously-planted diamond seed to induce diamond formation. Rather, the present invention forms carbon tetracarbide in situ by combinatorial synthesis and then, in the aggregate, diamond mass without the use of any extrinsic diamond seed to induce diamond formation. The diamond unit cell or carbon tetracarbide formed in situ is not an extrinsically added diamond seed.
Measuring diamond purity: purity of diamond may be gauged by Raman spectroscopy and/or Fourier transform infrared (FTIR) spectroscopy, for example. Both techniques are well known to those skilled in the art. However, any known analytical methodologies or instrumental techniques may be used to both measure purity of, and characterize, diamond mass produced.
Sensor bus, main system bus, and controller bus: refer to the communication system “wiring” pathways that transfer data and/or signals between components that comprise a computerized system for determining, monitoring and/or modifying a chemical or physical, process variable or variables. See, for example, US 2013/0031285 A1 and U.S. Pat. No. 5,469,150, which are both incorporated herein in the entirety. See also U.S. Pat. Nos. 4,886,590 and 6,590,131, which both describe chemical process control systems. Both U.S. Pat. Nos. 4,886,590 and 6,590,131 are also incorporated herein in their entirety. Further, control systems are known wherein various types of instrumentation, such as GC-MS, have been used to provide input data for modification of chemical processes. See, for example, U.S. Pat. No. 8,080,426 B1, which is incorporated herein in the entirety.
Reaction temperature: refers to a suitable temperature for conducting the combinatorial synthesis, which is no more than the decomposition or vaporization temperature of the tetrahedranoidal compound used therein. The decomposition or vaporization temperatures of exemplary tetrahedranoidal compounds are disclosed hereinbelow. Notably, the reaction temperatures used are always much less than substrate temperatures used in all chemical vapor deposition (CVD) techniques. For example, the following four exemplary tetrahedranoidal compounds have the indicated vaporization temperatures: benzvalene (77.5° C.), tetrahedranone (37° C.), dihydrobenzvalene (78.5° C.) and diazabenzvalene (−60° C.). Hence, when each of these tetrahedranoidal compounds is used in the combinatorial synthesis, the reaction temperature and substrate temperature (if a substrate is used to collect deposited diamond) must not go much above the vaporization temperature indicated for each tetrahedranoidal compound as indicated. The temperatures used in accordance with the combinatorial synthesis are readily distinguished from CVD processes, which necessarily use substrate temperatures in the range of 800° C. to 1,000° C. Such CVD substrate temperatures are far in excess of the maximum temperatures used with the present apparatus, and the use of such high CVD temperatures would destroy any of the tetrahedranoidal reactant compounds before they could participate in the combinatorial synthesis reaction.
Predetermined Sequence: means a defined sequence, prior to reaction, of reactant flows, temperature and pressure into, within, and out of a reaction chamber calculated to produce either merely operable conditions to facilitate production of diamond mass or preferred conditions for achieving production of diamond. This sequence is controlled by control signals sent from a systems controller to actuators in the apparatus of the present invention.
Single carbon atoms, atomic carbon, or excited state carbon atoms are used herein interchangeably, but in all cases single carbon atoms are intended as these react with tetrahedranoidal compounds in the combinatorial synthesis. Reactant solvents: means any solvent that is used as vehicle for at least one reactant used in the combinatorial synthesis of diamond. It is important that any solvent used as a solvent vehicle be of high vapor pressure (under ambient conditions) to facilitate solvent evaporation from both reactants prior to application of the high energy discharge. As a non-limiting example, methylene chloride (CH2Cl2) may be used as a solvent vehicle for any of cubane, benzvalene, dihydro-benzvalene, tetrahedranone or 3,4-diazabenzvalene.
Cubane may also be solubilized by short chain hydrocarbons (e.g., pentane, hexane, etc.). A co-solvent mixture may also be used. Other suitable solvents and co-solvents may be used as may be suggested to those having ordinary skill in the art.
Means configured for providing tetrahedranoidal reactant molecules to the reaction chamber: includes, for example, a conduit comprised of glass, metal or quartz, which are necessarily unreactive with and inert to the tetrahedranoidal reactant molecules. The conduit may optionally be provided with an inlet pump for pressuring the flow of inert gas which is mixed with a tetrahedranoidal reactant. The metal may be, for example, stainless steel or aluminum.
Means configured for providing a reactant source of single carbon atoms to the reaction chamber: includes, for example, a conduit comprised of glass, metal or quartz, which are necessarily unreactive with and inert to the single carbon atoms. The single carbon atoms are delivered in admixture with inert gas to the reaction chamber.
Means configured for generating single carbon atoms from the reactant source in the reaction chamber: includes, for example, microwave discharge generator, RF radiation, laser radiation, and electrostatic discharge.
The present invention provides diamond products that are produced with a quality and form that are impossible to achieve using conventional technologies. To date, conventional diamond technologies have been incapable of consistently producing a wide array of diamond products both economically and in industrial quantities. Further, conventional diamond-producing methods have proved unable to reliably produce ultra-pure, macroscopic, three-dimensional diamond articles of arbitrary, predetermined shape without complicated post-processing steps. Additionally, conventional methods of producing diamond are limited by their reliance on high temperature CVD processes or high-pressure/high-temperature (HPHT) techniques, which precludes the use of deposition substrates that would be destroyed by such extreme process conditions. Unfortunately, the tremendous technological potential for the use of diamond as a material for a vast number of applications has yet to be realized because of the limitations of conventional diamond-producing methods. The present invention represents an advance in the art that answers the heretofore unmet need for diamond production methods that yield high quality diamond materials in quantities that are reasonable in cost.
One object of the present invention is produce carbon tetracarbide, i.e., what the inventors refer to as the “diamond unit cell”, by implementing the reaction between a tetrahedranoidal compound and a carbon atom, i.e., the combinatorial synthesis. A further object of the invention is to produce a diamond mass by depositing carbon tetracarbide on a substrate using the combinatorial synthesis therefor at temperatures that are significantly lower than conventional art methods, such as CVD and HPHT.
Another object of the invention is to produce diamond that is ultra-pure, i.e., substantially free of graphitic and other impurities that in significant quantity would impair the use of the diamond in semiconductor and related applications. A still further object of the invention is to form diamond on substrates that would otherwise be destroyed by the extreme temperatures currently used in CVD and high-pressure/high-temperature methods of making diamond. An additional object of the present invention is to controllably fabricate three-dimensional diamond structures of predetermined shape. Yet another object of the present invention is to mold macroscopic structures of diamond. A yet further object of the invention is to provide an apparatus that controllably builds three dimensional diamond masses of predetermined morphology by providing for the necessary conditions for the combinatorial synthesis of carbon tetracarbide (i.e., the diamond unit cell as defined herein). Still another object of the invention is to provide an apparatus that renders a diamond mass shapeable according to predetermined morphology.
The Reaction Chamber
In one embodiment, these objects and more are achieved in a reaction chamber by providing a source of tetrahedranoidal molecules as a reactant, providing a source of carbon atoms as another reactant, and reacting the two reactants to form diamond deposited on a substrate. In the vapor phase, this reaction is performed in the presence of one or more carrier gases. Although the diamond forming method of the present invention can be performed in the vapor phase, this process is different from the chemical vapor deposition (CVD) methods for forming diamond. The present invention produces carbon tetracarbide which may be thought of as diamond at the molecular level, that is, by forming the diamond unit cell, i.e., the fundamental unit of diamond that is made up of five carbon atoms arranged as a tetrahedron with one carbon at each of the four apices and a fifth carbon in the center, “cage,” position. It starts with a reactant whose structure is close to that of the diamond molecule and, with the addition of a single carbon atom, is thermodynamically-driven to become diamond. This is in contrast to CVD methods that rely on directly applying high energy to carbon atoms with the precarious expectation that these atoms will assemble into a diamond film, but it is usually by an inefficient and expensive process that yields less than pure product. In the solid state, this reaction of the present invention is performed by evaporating a homogeneous solution of the reactants to yield a homogeneous solid mixture of the reactants, and then exposing the reactant mixture to a bond-cleaving, high energy discharge, thus releasing carbon atoms from the carbon source and causing carbon tetracarbide to form, which then forms diamond mass by crystallographic propagation. The reaction chamber includes inlet ports and at least one effluent port, temperature control means, flow control means, effluent monitoring means, sensors and actuators, and a system controller for receiving measured parameters and adjusting controls to increase diamond formation. The system controller includes a software program.
In another embodiment, an apparatus is provided to produce diamond mass that is produced from the carbon tetracarbide in the vapor phase. The apparatus includes a reaction chamber with at least one work piece holder for holding a deposition substrate, an effluent port remote from the substrate, a monitor for monitoring the chemical composition of the effluent, a means for controlling the deposition substrate temperature, a means for controllably evaporating a tetrahedranoidal compound in a flow of inert carrier gas, a means for directing the flow of the tetrahedranoidal compound in the inert carrier gas to the vicinity of the deposition substrate, a means for controllably providing carbon atoms in an inert carrier gas, a conduit adapted to convey the carbon atoms into the flow of the tetrahedranoidal compound in the inert carrier gas in the vicinity of the deposition substrate, a means for diverting the inert carrier gases with the tetrahedranoidal compound and the carbon atoms, sensors and actuators, and a system controller. In addition the reaction chamber may have a means for controlling the pressure within the reaction zone.
In yet another embodiment, an apparatus is provided to produce a diamond mass from carbon tetracarbide (i.e., the diamond unit cell as defined herein) that is produced in the solid state. The apparatus includes a reaction chamber, a means for introducing an inert gas into the reaction chamber, at least one work piece holder in the reaction chamber for holding a deposition substrate, a reservoir for holding a homogeneous reactant solution of a tretrahedranoidal compound and a carbon source compound, a reactant dispenser in the reaction chamber for dispensing the homogeneous reactant solution, the dispenser being movable in three-dimensions to a predetermined location in the reaction chamber, a conduit for conveying said homogeneous reactant solution from the reservoir to the dispenser, a means for controlling the temperature of a deposition substrate, an effluent port disposed in the reaction chamber remote from the at least one work piece holder, a monitoring means for monitoring effluent content, a switchable high energy discharge means for cleaving bonds of the carbon source compound thereby releasing carbon atoms, a system controller for controlling pressure within the reaction chamber, flow of the reactant solution to the dispenser, relative position of the dispenser with respect to a deposition substrate, dispensing of the homogeneous reactant solution, activation of the switchable high energy discharge means, and timing of the process sequence, wherein the monitor provides information governing timing of the reaction process and the sequences thereof. In addition the reaction chamber may have a means for controlling the pressure within the reaction zone.
Further, attention is directed to specific embodiments described in
Diamond is the allotrope of carbon whose now experimentally-determinable unit cell (the smallest unit of atoms that constitute the crystalline form of carbon known as diamond, and not a theoretical crystallographic construct) is a 5-membered tetrahedron having 4 carbon atoms occupying the apices of the tetrahedron and a fifth carbon atom located centrally within the tetrahedron (the “cage” position). This C5 tetrahedron is the “building block” for all diamond masses made therefrom. The carbon-carbon bond lengths, strengths, and bond angles are the same for all carbon atoms that comprise the diamond unit cell. They are short, strong, sp3 hybridized bonds.
Combinatorial syntheses of this experimentally-determinable diamond unit cell are disclosed in U.S. Pat. No. 8,778,295 and U.S. Pat. No. 9,061,917, which are fully incorporated herein by reference in their entirety. The conditions under which this diamond unit cell (also referred to herein as carbon tetracarbide) and consequently a diamond mass containing these unit cells, form combinatorially are mild and altogether different from conventional diamond forming methods such as high pressure, high temperature (HPHT) and chemical vapor deposition. These syntheses proceed by the reaction of an excited state carbon atom with a tetrahedranoidal molecule with concomitant ejection of leaving groups to form the carbon tetracarbide, the experimentally determined diamond unit cell, or C5-building block. The C5-building block diamond unit cell produced by these combinatorial reactions is a homo-penta-atomic molecule comprised of 5 carbon atoms. While not intending to be bound by theory, it is believed that the excited state carbon atom “inserts” into the unit cell cage position.
As disclosed in U.S. Pat. Nos. 8,778,295 and 9,061,917, the conditions under which the carbon tetracarbide, and consequently a diamond mass containing these carbon tetracarbide units, form are mild and altogether different from conventional diamond forming methods such as high pressure, high temperature (HPHT) and chemical vapor deposition. The disclosure of US 2015/0259213 is directed to means of exploiting the combinatorial syntheses of the diamond unit cell as defined herein to produce diamond masses comprising diamond unit cells and articles comprised of such diamond masses that have been previously unavailable by conventional diamond forming methods due to the strenuous conditions of these conventional methods. US 2015/0259213 is also fully incorporated herein by reference in the entirety.
The syntheses of carbon tetracarbide (and the resulting diamond masses so produced therefrom) proceed by a combinatorial reaction. That is, a first species reacts with a second species to produce a product that is carbon tetracarbide. The first reactive species is a carbon atom. The second reactive species is either a tetrahedral hydrocarbon molecule or tetrahedranoidal molecule. Indeed, tetrahedrane itself is a tetrahedranoidal molecule. In the case of U.S. Pat. No. 8,778,295, atomic carbon atom reacts with a transient intermediate produced by the catalytic treatment of acetylene in the vapor phase to form the experimentally-determinable diamond unit cell with concomitant ejection of hydrogen. This diamond unit cell as defined herein is formed on the deposition substrate from the vapor phase. We believe that the product of acetylene catalysis is tetrahedrane. Tetrahedrane has never been observed or isolated, but the results of the reaction disclosed in U.S. Pat. No. 8,778,295 strongly suggest that tetrahedrane is the reactant that produces diamond by reacting with a carbon atom.
One skilled in the art may review U.S. Pat. No. 8,778,295, for a more detailed understanding of the synthesis of carbon tetracarbide the diamond unit cell by this method.
The vapor phase synthesis of diamond disclosed in U.S. Pat. No. 9,061,917 proceeds by a related combinatorial synthesis wherein a carbon atom reacts with a tetrahedranoidal molecule with concomitant ejection of hydrogen and a “leaving or ejection group” to form the diamond unit cell, which deposits from the vapor phase onto a deposition substrate.
A tetrahedranoidal molecule is depicted generically by the following structure, which can serve as a selection guide.
Note that the structure exhibits a tetrahedral geometry except that in the base, an ejection group, shown generically as X, is “inserted” in place of a C—C bond. It functions to stabilize the tetrahedranoidal structure of the molecule. X is preferably a volatile substance that can quickly leave the tetrahedranoidal molecule as it reacts with a carbon atom to form diamond. If a less volatile group is used to stabilize the tetrahedranoidal molecule, the purity of the diamond product formed by the reaction may be diminished. There may be times, however, when impure diamond is desired. Although other leaving groups can be used, for the purposes of the present invention, that is, for producing purer diamond, preferred leaving groups include: —CH═CH—, C2H4, CO, or —N═N—. Thus, in view of the above, one with ordinary skill in the art can select a variety of tetrahedranoidal compounds that can be used as reactants for the present invention.
Thus, the preferred tetrahedranoidal molecules that may be used are, benzvalene or 2,3,4-methynylcyclobutanone (non-IUPAC naming for clarity) or any other tetrahedranoidal molecule having a stabilizing species inserted into the C—C bond. Benzvalene and 2,3,4-methynylcyclobutanone are tetrahedranoidal molecules that are stable and isolable compounds. Structurally, they are tetrahedranes having a species “inserted” between two carbon atoms in place of a direct C—C bond. It is this “insert species” that is the “leaving group” of this vapor phase diamond unit cell synthesis. One of ordinary skill in the art will understand that any tetrahedranoidal molecule having sufficient stability and vapor pressure may be used in the diamond forming reaction of the present invention. For example, various bicyclobutane compounds may be used. Their synthesis is known. See Journal of the American Chemical Society, 89:17, Aug. 16, 1967. Tetrahedrane, itself, is a tetrahedranoidal molecule or compound, and, as such, falls within the definition of “tetrahedranoidal compound” as used herein in accordance with the present invention.
In the case of benzvalene, the “insert species” is —HC═CH— (ethylene). In the case of 2,3,4-methynylcyclobutanone, the “insert species” is CO. In the case of dihydro-benzvalene, the “insert species” is C2H4.
Benzvalene (C6H6) bp=77.558° C. (760 mm Hg) vapor pressure 106.123 mm Hg at 25° C.
2,3,4-methynyl-cyclobutanone (“Tetrahedranone”, “Carbonyl tetrahedrane”, C5H4O) bp≈37° C. (some decomposition).
Dihydro-benzvalene (C6H8) bp=78.5° C. (760 mm Hg) vapor pressure 102 mm Hg at 25° C.
Stable, isolable tetrahedranes are known, but they bear sterically bulky substituents on reactants for the carbon tetracarbide (“diamond unit cell”) forming reactions of either disclosure.
A solid-state diamond unit cell forming reaction is also disclosed in U.S. Pat. No. 9,061,917. In this reaction, a homogeneous mixture of cubane and tetrandranoidal molecule having a tetrahedranoidal molecule-to-cubane (molar) ratio optimally of 8:1 is subjected to a high energy discharge for a time sufficient for completion of the formation of a diamond mass containing carbon tetracarbide units. Benzvalene, dihydro-benzvalene, and 2,3,4-methynylcyclobutanone may be used as the tetrahedranoidal molecule, and 3,4-diazabenzvalene may also be used as the tetrahedranoidal molecule (2,3,4-methynyl-pyrazoline, C4H4N2; decomposes at about −60° C.).
The carbon tetracarbide (“diamond unit cell”) forming reaction of U.S. Pat. No. 9,061,917 occurs as follows.
A plurality of carbon tetracarbide units so formed assemble to form a diamond mass. Thus, the diamond mass is formed by the assembly of a plurality of carbon tetracarbide units.
(It is noted here that the term “diamond molecule” has been incorrectly used for diamondoid molecules and masses of diamondoid molecules such as adamantane. In fact, adamantane is a hydrocarbon whose structure is unrelated to that of carbon tetracarbide or diamond mass as disclosed herein.
The role of cubane is the same for both disclosures (U.S. Pat. No. 8,778,295; U.S. Pat. No. 9,0619,17) in both the vapor phase and solid-state carbon tetracarbide forming reactions. Cubane is a source of atomic carbon as it can be decomposed cleanly to carbon atoms and hydrogen by a high energy discharge (e.g., microwave, but not limited to microwaves) without the complications of meta-stable radical impurities that would the disclosed carbon tetracarbide forming reactions.
Cubane is stable and can be evaporated such that, through multiple sublimations, it can be made to have very high purity. Cubane has 166 kcal/mole of strain energy due to its 90° carbon-carbon bond angles, which likely explains its advantageous use as a source of carbon atoms. Indeed, cubane is a better carbon atom source than the customary hydrocarbons (e.g., methane, etc.) currently used in conventional CVD methods for making diamond. It yields carbon atoms uncomplicated by hydrocarbenoid impurities, which can interfere with the assembly of carbon atoms to produce diamond. As such, the rate of formation is likely to be faster than those current CVD processes that employ the customary carbon sources.
Cubane is uncomplicated by the meta-stable radical impurities typically encountered with other prior art carbon sources used in conventional syntheses. For example, methane, the most commonly employed carbon source produces methyl radicals, di-radical methylene, and tri-radical methyne species under thermal or electromagnetic energy decomposition methods.
The following shows the decomposition of cubane and thus its use as a carbon source.
According to Nicoll et al. (Environ. Sci. Technol. 1998, 32, 3200-3206): “There is a dearth of reports in the literature on atomic carbon reactions in general. The lack of studies of this system is mainly due to a lack of clean sources for producing atomic carbon.” Although this was published in 1998, little progress seems to have been made since then in developing clean sources of atomic carbon. Thus, the decomposition of cubane to produce atomic carbon is an important step forward in and of itself.
Despite the excellence of cubane as a source of atomic carbon, other, currently less optimal approaches for producing atomic carbon may be considered. For example, the sequential radiolysis of methane performed up to four times would yield four hydrogen atoms and a carbon atom for use in the combinatorial synthesis of diamond. Such a sequential radiolysis would proceed as follows:
1) CH4 [hν1]→CH3·+H·(some .CH2.; CH.; C)
2)→[hν2]→·CH2·+H·(some CH.; C)
3)→[hν3]→·CH: +H·(some C)
4)→[hν4]→C+H.
Producing “cleaner” or “clean” carbon atoms from methane by sequential radiolysis may require the use of mass filters to feedback or exclude the unwanted intermediates from the flow.
Carbon atoms in a carrier gas can be produced by laser ablation of graphite as described by Kaiser et al. (Rev. Sci. Instrum. 66 (12), December 1995).
In WO2015197047, Huisken et al. describe an atomic carbon source that is putatively free of carbon clusters and other impurities. A carbonaceous source is heated to liberate carbon atoms, which can be used for a variety of applications.
Atomic carbon from any source can be used in the present invention if it has sufficient kinetic energy, is monoatomic and clean, and sourced from an apparatus that can be effectively integrated with the apparatus described herein. However, sequential radiolysis, laser ablation of graphite, or heating of a carbonaceous source are unlikely to produce carbon atoms as efficiently, cleanly or in sufficient quantity as the radiolysis of cubane. It is important that the carbon source for the combinatorial reaction provide neither carbon clusters nor carbon molecules but, rather, single carbon atoms.
To obtain a mass of high purity diamond suitable for optical and semiconductor applications, the materials scientist will recognize that this method of diamond synthesis does not use the energy of the deposition substrate as part of the diamond unit cell forming reaction. This allows substrate materials, which could never survive the rigorous conditions of prior art diamond syntheses, to be used as deposition substrates. It also allows for the use of a production apparatus that would fail under prior art syntheses conditions. For example, the range of possible materials that can be used for the reaction chamber of the present invention is much greater than can those that can be used in CVD systems, which operate at much higher temperatures that those of the present invention.
In selecting materials for the apparatus of the present invention, it is important to avoid those that can react with components of the combinatorial process. For example, certain plastics can outgas contaminants. Material components of the apparatus are chosen so as not to erode and breakdown but, rather, to be durable and chemically inert. For example, to avoid carbon contaminants, carbon-based polymers are undesirable and their use as apparatus components should be minimized. However, in comparison to CVD and HPHT systems, the milder reaction conditions of the present invention allow for a much greater range of materials that can be selected for constructing the apparatus.
The vapor phase reaction of combinatorial synthesis of diamond has been performed in glass reaction chambers, but other materials such as quartz or stainless steel (may include glass or quartz windows) or aluminum can be contemplated for use. Metal surfaces within the reaction chamber can be passivated with platinum or palladium, as is well known by those with ordinary skill in the art. The solid state reaction of the present invention has been performed within a PTFE-lined glass tube, which would certainly not survive the typical conditions of a CVD diamond reactor or, clearly, HPHT systems.
The mechanical, electronic and software aspects of the present invention are constructed with a strong emphasis on modularity. This facilitates cleaning, maintainability, repair, and parts replacement. It also yields a system that can be modified easily to produce diamond with a wide range of specification options such as geometry (e.g., thickness), shape, choice of substrate material, etc. Operational parameters (i.e., for sensors and actuators) can be selected within a system controller through a graphical user interface to control the desired production process.
The disclosed carbon tetracarbide synthesis does not proceed by the assembly of carbon atoms (i.e., atomic motion on a surface) to form diamond. That is, it is not driven by surface kinetics. The result is that graphitic and amorphous carbon impurities typically observed for diamond produced by HPHT methods are not found in diamond masses produced by the combinatorial syntheses. Non-stoichiometric C—H impurities within the diamond lattice typical of prior art CVD diamond syntheses are also not observed in diamond masses produced by the combinatorial syntheses because the carbon atom source (cubane) does not produce the C—H impurities that complicate CVD diamond produced from hydrocarbons such as methane. The rate of diamond formation for the syntheses is very fast compared to prior art high pressure/high temperature (HPHT) and
chemical vapor deposition (CVD) diamond methods. The rate of diamond formation does not rely upon assembly of carbon atoms to form a diamond mass as is the case in diamond produced by prior art CVD methods. Rather, it is solely dependent upon chemical kinetics—the rate at which the reactants can be provided and combine to produce carbon tetracarbide. Thus, the speed of formation of a diamond mass using the present invention is a function of the rate at which reactants can be provided. On the other hand, the chemical reaction per se of a tetrahedranoidal compound with a carbon atom is both thermodynamically and entropically driven. In the diamond forming process disclosed in U.S. Pat. No. 8,778,295, a carbon atom reacts with what we believe is tetrahedrane (an acetylene-derived, catalytically produced intermediate), producing one unit cell and four hydrogen atoms. Disorder increases from two to five, a net entropy change of three. Furthermore, diamond is thermodynamically stable while tetrahedrane is most definitely not. It is highly unusual and, indeed, surprising to have any chemical transformation that is favored both by entropy (increase in disorder) and thermodynamics. In the diamond forming process of U.S. Pat. No. 9,061,917, a carbon atom reacts with a tetrahedranoidal compound, for example, benzvalene. Diamond forms along with four hydrogen atoms and one ejection product or “leaving group,” which is HC═CH (acetylene). This results in the two reactants producing one diamond unit cell, four hydrogen atoms, and one acetylene. Two goes to six, a net entropy change of four. Thus, in the reactions of both disclosures, the products are at a higher state of entropy than the reactants.
In “Chemthermo: A Statistical Approach to Classical Thermodynamics” (1972), by Leonard Nash, an example is provided regarding the conventional geologic conversion of graphite to diamond from a Gibbs “free energy” perspective. First, the mere fact that the density of diamond is 3.5 gm/ml, and that of graphite is 2.25 gm/ml, alone, suggests that an enormous amount of pressure is involved in the natural process of converting graphite to diamond. Second, Nash calculates an equilibrium pressure between graphite and diamond formation to be 75,000 atm. at 1,500° K. This translates to a depth of over 400 miles deep in the earth at a temperature of about 2240° F. Any higher pressure and/or temperatures above these points increasingly thermodynamically favor diamond production. Additionally, as already noted in US 2014/0150713, “ . . . in the region where diamond is metastable compared to graphite, synthesis of diamond under CVD conditions is driven by surface kinetics and not bulk thermodynamics.” Thus, it is unsurprising that many prior art processes for producing diamond rely either on high temperatures (in CVD processes) and high pressures and temperatures in HPHT processes. It could well be said that developers of CVD and HPHT processes for making diamond intuitively attempt to emulate nature. But nature doesn't make high purity diamond, much less high purity diamond films suitable for semiconductor, optical, and other technological applications. Thus, in view of current diamond synthesis technologies, it would appear surprising and counterintuitive to one with ordinary skill in the art that it is possible to produce a diamond mass at ambient and even very low temperatures.
Furthermore, it may also appear surprising to one skilled in conventional diamond-forming technologies that the present invention's disclosed reactions can also be performed at atmospheric pressure. In contrast to conventional diamond syntheses, which require the imposition of high temperature, the reactions of the present invention are driven by the chemical bond energies of the reactants themselves and, in fact, in fact, are conducted at temperatures which cannot be much above the vaporization or decomposition temperatures of the tetrahedranoidal reactant molecules.
In the present invention, product purity is controlled by stoichiometry, that is, sufficient excesses of tetrahedrane or tetrahedranoidal reactants are provided to consume all the carbon atoms produced. The purity of the diamond product obtained by the disclosed combinatorial syntheses is also a consequence of the purity of the reactants, and this is readily maintained at research purity by using standard chemical purification techniques well known to those with ordinary skill in the art of chemical synthesis.
The combinatorial synthesis provides the materials scientist with a consistent and reliable source of high purity diamond that is extremely difficult to obtain by other conventional diamond syntheses. It also produces diamond masses much faster than other diamond syntheses, and this is a significant economic advantage of the present invention.
The combinatorial synthesis may also provide the materials scientist with a form of diamond heretofore unavailable by other diamond syntheses. Specifically, replacement of atomic carbon with a heteroatom can produce a diamond homologue, or heterodiamond, having a heteroatom inserted into the cage position of the C5-building block rather than a carbon atom. The heteroatoms suitable for preparing a hetero-diamond homologue include nitrogen (from ammonia or hydrazine) and boron (from borane or diborane) as they have the appropriate bond order capability (4) and atomic size for insertion into tetrahedrane or a tetrahedranoidal molecule to form a heteroatom tetracarbide C5-building block. Such a heteroatom tetracarbide species would be an electret because it would bear a charge without a countercharge. This may introduce the possible use of product heterodiamond as a highly electrically conductive material at room temperature because, at room temperature, diamond displays a very low RMS vibration (0.002 nm).
Diamond has many desirable properties. Due to short, strong, and uniform bond lengths, strengths, and angles, diamond has a hardness of 10 on the Mohs scale, the hardest material known. It has exceptional chemical stability, igniting in air at about 1,000° C. and in pure oxygen at about 700° C.
These properties account for diamond's use in a wide variety of cutting and abrading applications. The high room temperature thermal conductivity of diamond, about 2,000 W/cm-° K, and its low coefficient of friction, 0.05-0.08 make diamond a particularly useful material for bearings and other tribological applications. By comparison, tungsten carbide has a coefficient of friction of about 0.2-0.25 under the same conditions. Due to its relative ease and economy of preparation, polycrystalline diamond is frequently employed as a bearing surface. Applications that exploit these mechanical properties of diamond (cutting abrading, and low friction surfaces (bearings, coatings for mammalian joint replacement devices, etc.), do not require extremely high levels of purity.
Diamond has a high index of refraction (2.4), and optical transparency from infrared through visible wavelengths. UV fluorescence observed for diamond attributed to flaws is used by gemologists in sorting and grading naturally occurring diamonds and to separate mineral diamond from impurities such as garnet. Diamond has been found to be both x-ray fluorescent and x-ray transmissive. When pure or dopant free, it may be used in place of beryllium as an x-ray window. However, diamond has also been observed to fluoresce green upon exposure to x-rays. This fluorescence has been attributed to impurities or dopants as well as flaws in naturally occurring diamond, a property also exploited by gemologists in grading and sorting of diamonds. A band gap of 5.45-5.47 eV renders diamond a superb electrical insulator (1016 ohm). Boron doped (blue) diamond has been found to be p-type semiconductor having a high hole mobility and electrical breakdown strength. These properties make diamond highly desirable as a material for applications including, but not limited to, semiconductor devices, optoelectronic devices, directed energy device windows and lenses, optical devices such as windows, prisms, mirrors, and lenses, and electromagnetic shielding. The combination of high thermal conductivity and high electrical resistivity available in diamond of very high purity make it attractive as a semiconductor substrate. Exploitation of such properties of diamond as a material in these applications requires that diamond be ultra-pure—far beyond the purity requirements for diamond in cutting, milling, low friction surface applications, and gemstones. For example, it is estimated that diamond requires an impurity level less than 100 parts per million if it is to be used as a semiconductor, with an impurity level of less than 10 ppm being most desirable. Optical use, particularly for directed energy device (e.g., lasers) windows and lenses also requires similar low impurity levels as do optoelectronic device applications. Thus, a need exists for synthetic diamond products produced using a process that yields extremely high purity, or ultra-pure, diamond. There is also a need for synthetic diamond products produced using a process that can be performed at low temperatures. Such a process allows the use of substrates, shapes, and forms made from materials that would be destroyed at the high temperatures typically associated with synthetic diamond producing processes of the related art. This process allows the use of substrates, molds, and forms made from materials that can be more easily worked, are less expensive, and from which a diamond mass can be more easily removed than previous methods of producing synthetic diamond. There is yet another need for synthetic diamond products that can be shaped during the production process. Current processes of the related art typically produce a single layer or coating of synthetic diamond on a substrate surface and cannot be used to produce diamond masses with a variety of predetermined shapes. That is, while current processes may produce a diamond product that reflects the shape of its deposition substrate, these diamond products are not shapeable upon the substrate according to a predetermined morphology. Furthermore, current processes are typically incompatible with the use of molds that confer a predetermined, three-dimensional shape to a diamond mass. Typical diamond processes such as CVD and HPHT methods cannot deposit diamond mass material on selected portions of a substrate through the use of nozzles or other reactant conduits that direct and focus combined streams of reactants at a specific target area of the substrate. There is similarly a need for a diamond synthesis process that can produce a diamond mass with a predetermined, three-dimensional shape. There is also a need for synthetic diamond products that are produced by a process that yields a diamond mass quickly and efficiently enough to be economically beneficial for mass production. Thus, there is a need for a synthetic process for producing a diamond mass that grows at around a millimeter of thickness per hour or faster. There is a further need for extremely pure synthetic diamond products produced using a process that is controllable in terms of such parameters as reactant delivery, reactant purity, effluent flow, product purity, product shape, crystal morphology, and dopant or impurity content. Multiple controllable parameters in the needed processes allow for the use of automatic control methods that currently use microcontroller means including microcomputers, sensors, and various actuators known in the art. These processes should be controllable in three-dimensions. Furthermore, there is a need for a synthetic diamond mass producing process that is thermodynamically driven, the speed of which reaction is primarily dependent upon the speed at which reactants can be provided, as opposed to a process that depends primarily upon surface kinetics.
The present invention uses the combinatorial reactions disclosed in detail in U.S. Pat. No. 8,778,295 and U.S. Pat. No. 9,061,917, which are incorporated herein by reference. Two vapor phase reactions are disclosed, both of which require a carbon atom source that reacts with a tetrahedranoidal compound to form molecular diamond. One method uses what is believed to be tetrahedrane, produced by the catalytic dimerization of acetylene as the tetrahedranoidal reactant. The other vapor phase reaction uses other tetra hedranoidal compounds (e.g., benzvalene, 2,3,4-methynyl-cyclobutanone, etc.) such as have been discussed above. When a stoichiometric excess of these compounds is reacted with the carbon atoms provided, for example, from cubane that has been radiated with an energy source such as microwaves, carbon tetracarbide units are formed that then combine it is surmised by crystallographic propagation to yield a diamond mass. A solid-state reaction that yields a diamond mass is disclosed in detail in U.S. Pat. No. 9,061,917.
Examples of the Reaction Chamber and Operable Connections between the Provision of Reactants and the Reaction Chamber
The plasma of the present invention has a different function than the plasma used in chemical vapor deposition processes for producing diamond. CVD systems typically use a plasma to provide reactive carbon-containing radicals in a process driven by surface kinetics to form diamond that is inherently contaminated with non-diamond species. Hydrogen, which is inherently part of the CVD process, is used to etch away some of these contaminates, and is thought to help prevent the formation of graphite. However, hydrogen is itself a contaminate of diamond.
Although the preferred source of atomic carbon in the present invention is cubane radiolysis, as has been noted above, the present invention comprehends other sources of atomic carbon. These include sequential radiolysis of methane, laser ablation of graphite, the heating of a carbonaceous material, etc. Each of these methods can also be used in association with an argon carrier gas that has been exposed to a high energy discharge, such as microwave energy, to provide the dilution and plasma benefits noted in the mass spectrum of cubane radiolysis.
It should be noted that cubane radiolysis can be an excellent source of atomic carbon for many other applications because atomic carbon is extremely reactive. Indeed, even though the present invention is completely different and distinguished from CVD methods of producing diamond, cubane radiolysis would likely be a much better source of carbon than methane in the CVD production of diamond.
The substrate 4 of
The purpose of the embodiment of
Once the diamond mass 6 of
During the formation of diamond mass 6, the diamond forming process can be performed so as to combine the diamond with at least one other material with dissimilar properties to produce a diamond-based composite. The properties and characteristics of such a diamond composite will be different from those of any one of the component materials as measured or determined alone. Diamond composites are known in the art, but these are produced by conventional processes such as chemical vapor deposition or sintering. For example, in WO2017/032842, Sundström et al. describe the sintering of diamond particles within a binder matrix such as SiC. Their process can involve temperatures as high as 1650° C. In their paper titled “Cu/synthetic and impact-diamond composite heat-conducting substrates,” Galashov et al. describe a composite material with high thermal conductivity produced by the thermal sintering of diamonds (synthetic and impact) and copper powder and by further hot isostatic pressing. Their process involves sintering copper diamond substrates at 900° C. and a pressure of 10−3 Pa for 1 hour.
The extreme conditions (e.g., temperature and/or pressure) used in these conventional processes to produce diamond composites limit the types of materials that can be used in making the composites. Just as the milder conditions of the present invention allow for a greater variety of substrates upon which diamond can be deposited, they also allow for a greater variety of materials that can be used to produce a diamond-based substrate.
For the purposes of the present invention, a diamond composite can be structured as a homogeneous composite (e.g., a mass that includes both diamond and at least one other material interspersed therein) and/or a non-homogeneous composite (e.g., a laminate composite comprising discrete layers of different materials including at least one layer of diamond).
Diamond films can be patterned and etched using, for example, hard masks of SiO2 and reactive ion etching/inductive coupled plasma or oxygen-plasma. Through the use of photolithography and related techniques, at least a portion of the diamond mass is removed from the substrate. However, the diamond mass may be removed entirely, for example, if it were to be used as mask, itself. Furthermore, the substrate 4 need not comprise solely a single material. Rather, it can be a complex functional structure that might include, for example, metal traces and pads, dielectric materials (e.g., SiO2), and semiconductor materials (e.g. doped and undoped silicon), etc. Substrate 4 may be an adhesion layer between another material and the diamond mass 6. Examples of such adhesion layers may be, but are not limited to, materials such as silicon nitride, silicon carbide, aluminum nitride, silicon, and the like.
By photolithography and related techniques is meant photolithography, electron beam photolithography or ion beam photolithography. For example, any type of lithography may be used, such as lens array photolithography (U.S. Pat. No. 6,016,185), semiconductor nano-sized particle-based photolithography (US 2011/0281221) and photolithographic systems using a solid state light source (US 2012/0170014), all of which U.S. patents and applications are incorporated herein by reference in the entirety.
Any electron beam photolithographic technique may also be used. For example, the electron bean may be simple (U.S. Pat. No. 5,767,521), multiple beam (U.S. Pat. No. 6,429,443) or parallel multi-electron beam (U.S. Pat. No. 7,075,093), all of which U.S. patents are incorporated herein by reference in the entirety.
Furthermore, any ion beam photolithographic technique may be used. For example, a masked ion beam (U.S. Pat. No. 4,757,208) may be used, which U.S. patent is also incorporated herein by reference in the entirety.
Below are just two examples of formed diamond mass and a substrate coated with diamond mass that are merely illustrative and are not intended to be limitative.
A teflon lined glass receiver cylinder having a 2 cm diameter and 5 cm wall height was placed in a Schlenck vessel having a threaded wide mouth, gas/vacuum port, and a septum port to which was attached an electronically controlled syringe pump. The vessel was sealed and evacuated followed by admission of argon and chilling in a dry ice/chlorobenzene bath (−45° C.). By the syringe pump, a first precisely standardized solution of 1 mmol of benzvalene in dry dichloromethane was delivered into the contained cylinder. A second precisely standardized solution of 0.125 mmol of cubane in dry dichloromethane was delivered to the contained cylinder to afford an 8:1 (molar) mixture of benzvalene and cubane in dichloromethane The syringe tube (needle) was removed, and argon flow was stopped. Vacuum was applied slowly to minimize bumping, and the solvent was removed under complete vacuum (about 10 minutes). Argon was readmitted when visual observation of the cylinder indicated that it contained a dry (solvent free) solid. A portion of the argon flow was sampled by gc/ms to confirm complete removal of dichloromethane and absence of benzene. The cold bath was removed. The vessel was transferred to load-lock of a glove box having an argon atmosphere, and the cylinder bearing the homogeneous mixture of solid cubane and benzvalene was removed from the Schlenck vessel and transferred to a microwave discharge cell. The cell was sealed, removed from the glove box, fitted with refrigerant lines to the cold plate on which the contained reaction cylinder was mounted, attached to the Schlenck line, attached to a gs/mc instrument at the cell effluent port, and refrigerant was circulated through the cold plate to maintain the reactant mixture at −45° C. Argon flow through the cell was initiated with commencement of gc/ms effluent monitoring. The cell was then energized to initiate the diamond forming reaction.
When gc/ms monitoring indicated the effluent to be free of hydrogen or acetylene (about 5 seconds), energy to the discharge cell was ceased, refrigerant circulation was ceased, and the cell was opened to recover the reaction vessel. The glassy disc within the cell was brought to an FT-IR reflectance instrument which confirmed the presence of diamond (1328-1332 cm−1). No graphite, amorphous carbon, or C—H peaks were observed. The weight of the disk was 59.12 mg (98.4% of theoretical).
A vapor phase diamond unit cell (carbon tetracarbide) forming reaction was performed as follows.
A teflon glass receiver cylinder having a 2 cm diameter and 5 cm wall height was placed in a Schlenck vessel having a threaded wide mouth, gas vacuum port, and septum port to which was attached an electronically controlled syringe pump. The vessel was sealed and evacuated followed by admission of argon and chilling in a dry ice/chlorobenzene bath (−45° C.). By the syringe pump a solution of 2 mmol of benzvalene in dichloromethane was delivered into the contained cylinder. A second teflon lined glass receiver cylinder having a 2 cm diameter and 5 cm wall height is placed in a second Schlenck vessel having a threaded wide mouth, gas vacuum port, and septum port to which was attached an electronically attached syringe pump. The vessel was sealed and evacuated followed by admission of argon and chilling in a dry ice/chlorobenzene bath (−45° C.). By the syringe pump a solution of 0.125 mmol of cubane in dichloromethane was delivered into the contained cylinder. The syringe lines (needles) were removed from both vessels. The flow of argon was ceased to both vessels. Vacuum was applied slowly to both vessels to minimize bumping, and the solvent was removed under complete vacuum (about 10 minutes). Argon was readmitted to both vessels when visual observation of the cylinders indicated that both contained a dry (solvent free) solid. A portion of the argon flow was sampled by gc/ms to confirm complete removal of dichloromethane and absence of benzene. The cold bath was removed. The vessels were transferred to the load-lock of a glove box having an argon atmosphere, and the cylinder bearing cubane was transferred to the evaporator contained within the microwave discharge cell and sealed. The benzvalene containing cylinder was transferred to an evaporation cell having gas/vacuum valved fittings which were closed. Both cells were transferred to a reactor, attached to gas/vacuum fittings, and configured for the diamond forming reaction by combinatorial synthesis. A silicon foil disk deposition target was heated to 85° C. Then, using pre-programmed values, gas flow, heating of both evaporators, and application of energy to the microwave discharge were initiated with monitoring of the effluent by gc/ms. When no more reaction products were detected by gc/ms, the reaction was terminated, and the substrate was allowed to come to ambient temperature, whereupon it was removed and weighed. Yield was 59.77 mg (99.5% of theoretical). FT-IR reflectance confirms that the glassy film deposited upon the substrate to be diamond showing no graphite, amorphous carbon or C—H peaks.
The process of
The process of
Reaction effluent is removed from the reaction chamber 10 through an effluent port that is not shown. Electronic and mechanical operations of the apparatus regarding parameters such as fluid flow, conduit/nozzle movement, pressures temperature, and other reaction parameters can be automated by means of a microcontroller or computer.
The apparatus of
Diamond masses 8a, 8b, and 8c of
The ganged delivery apparatus of
Thus, the apparatus of
A solid-state, combinatorial synthesis the of diamond unit cell reaction is disclosed in detail in U.S. Pat. No. 9,061,917. This is reaction 2b shown in
In solid state embodiments of the present invention, solvent evaporation is facilitated preferably by keeping the conditions within the reaction chamber at reduced pressure, that is, sub-atmospheric pressure. Both the pressure and temperature maintained and controlled within the apparatuses of the present invention are chosen according to the boiling point of the solvent, its vapor pressure, and the vapor pressure of the reactants. If extreme purity is desired such as, for example, for semiconductor or quantum applications, maintaining strict stoichiometric ratios of the reactants is necessary. Thus, a balance must be maintained between conditions that facilitate solvent evaporation and conditions that preserve the stoichiometry of the reactants in view of their vapor pressures. The ultimate control of reaction parameters and apparatus function is achieved with a system controller, which can be a dedicated computer, embedded microcontroller, or other programmable digital device well known in the art. Sensors and actuators can directly control parameters and system function through the use of temperature sensors, pressure sensors, flow sensors and actuators, which can include, for example, digitally controllable valves, pumps, and heating/cooling mechanisms well known in the art. Sensors and actuators typically communicate bi-directionally with a system controller via busses. Sensors and some actuators can be disposed in a single, integrated module at one location or, alternatively, placed at disparate locations in the system.
The carbon tetracarbide (i.e., diamond unit cell) forming reaction can be conducted in the solid state using a homogeneous mixture of cubane and any of the above-cited tetrahedranoidal compounds. This homogeneous blend is a molar ratio of 8:1, tetrahedranoid-to-cubane.
A cubane molecule decomposes to provide eight carbon atoms and eight hydrogen atoms. The skilled practitioner will recognize that a high degree of stoichiometric precision is required when preparing the homogeneous blend of cubane and tetrahedranoid if a diamond product of high purity is to be obtained by the diamond unit cell forming reaction. An excess of cubane (the carbon atom source) introduces graphitic and amorphous carbon impurities into the diamond product. Excess tetrahedranoid can introduce graphitic, carbenoid, and even heteroatom impurities into the diamond product. Gravimetric methods are unlikely to achieve this level of precision and are difficult to perform with contact-sensitive materials such as benzvalene and 2,3,4-methynylcyclobutanone; 3,4-diazabenzvalene is unstable above −60° C.
Forming stock solutions of the individual reactants (cubane and tetrahedranoid) can achieve this precision with the use of liquid chromatographic equipment in tandem with mass spectrometric instrumentation (HPLC-MS). Such equipment is commercially available and can attain five decimal place precision (and even higher for some research specification models). This equipment can readily identify and separate impurities common to tetrahedranoidal molecules. For benzvalene, the impurity that is observed is benzene. For 3,4-diazabenvalene and 2,3,4-methynlcyclobutanone (“tetrahedranone”), the impurity is dicyclobutadiene, which arises from the ejection of dinitrogen or carbon monoxide, respectively, from these tetrahedranoidal compounds. These are four-carbon units that probably form butadiene, which dimerizes to the final impurity, dicyclobutadiene. Thus, it is advantageous to use benzvalene as the tetrahedranoidal reactant for the solid-state diamond unit cell forming reaction. It is the most stable of the tetrahedranoidal compounds discussed hereinabove (except for dihydro-benzvalene), and it is fairly economical to use being readily prepared by standard organic synthesis methods from inexpensive reagents.
The use of precisely calibrated stock solutions of the individual reactants using HPLC-MS instrumentation also provides a means for maintaining the stoichiometric precision necessary for producing diamond by the solid state diamond unit cell forming reaction. The two solutions are combined to form a homogeneous solution of the reactants and this is then freed of solvent carefully at reduced pressure and at reduced temperature in the reaction vessel in which the diamond unit cell reaction occurs. The solid blend is held at low temperature in an inert atmosphere because the vapor pressures of the individual reactants are sufficient at ambient temperature (benzvalene: 106.12 mm Hg; cubane: 1.1 mm Hg) to alter the stoichiometric precision of the homogeneous blend by evaporative loss. The combination of double manifold line manipulations and HPLC-MS instrumentation simplifies the task of preparing a stoichiometrically precise blend of purified reactants as well as maintaining their purity and stoichiometry.
As detailed in U.S. Pat. No. 9,061,917, which is fully incorporated herein by reference, the homogeneous solution of the reactants is kept at a temperature known to suppress changes in the stoichiometric precision of the reaction, i.e., loss of reactant mass due to vapor pressure of the reactants. For example, in U.S. Pat. No. 9,061,917, the temperature of the cubane/benzvalene/dichloromethane solution is kept at −45° C. Since the reaction itself can occur at ambient temperature and pressure, the vehicle gas (e.g., argon) can be provided at ambient temperature and temperature, as well. However, the temperature and pressure can be altered quickly and in real time by the system controller as needed or as indicated by sensor data such as are provided by pressure, temperature, and optical sensors, and GC-MS, etc. The apparatus of the present invention comprises a highly responsive, feedback control system.
Although the process of
The diamond molding process of the present invention can be adapted to form three-dimensional, shapeable diamond masses whose shapes are controlled by the morphology of the mold, which, for the purposes of the present invention, is considered a type of substrate. For example, a cylindrical mold can be used to fabricate large cylinders of diamond. A mold can be used that approximates the rough shape of a faceted diamond gem to minimize waste when the gem is precision faceted. Flat, open, circular molds can be used to fabricate diamond wafers using the vapor phase or solid-state reactions of the chemistry shown in
As described above in relation to
In
In
The system disclosed provides for relative, three-dimensional movement between dispensing device 230 and substrate 204, which is held in a work piece holder (not shown). Thus, the dispensing device 230 and/or the substrate 204 (held in a work piece holder) can be moved with respect to each other. Furthermore, even though only one substrate 204 and dispensing device 230 are shown in
There is no limitation on the size and shape of diamond masses 214a and 214b. For example, by moving dispensing device 230 as homogeneous solution 202 is dispensed, a straight or curved line of homogeneous solid mixture 210a or 210b can be put onto substrate 204, which, after exposure to a high-energy discharge can yield a diamond mass 214a or 214b whose size and shape reflects the predetermined volume and pattern of the originally dispensed homogeneous solution 202. Furthermore, dispensing device 230 can be designed so as to comprise multiple pipettes or other fluid delivery devices either connected physically or controlled in such a way that they act in concert to dispense homogeneous solution 202 in a predetermined volume, shape, or pattern. There is no requirement that volume, shape, or pattern of each fluid delivery step be the same.
Homogeneous solution 202 can be prepared using a number of solvents. For the purposes of the present invention, the solvent should be chosen so that it is liquid at the reaction temperatures, solutes are fully and strongly miscible therein, and has a relatively high vapor pressure (i.e., is highly volatile) to facilitate rapid evaporation and thus quickly form a homogeneous solid mixture as exemplified, for example by homogeneous solid mixtures 210a, and 210b. While U.S. Pat. No. 9,061,917 details the use of dichloromethane as a solvent for the solid-state reaction of a tetrahedranoidal compound with a carbon atom to form the diamond unit cell, other solvents can also be used. As disclosed in U.S. Pat. No. 9,061,917, solvent was freed by evaporation from the reactant solution at a temperature of between −20° C. and −45° C. The boiling point (bp) of dichloromethane is 39.6° C. Other suitable solvents might include butane (bp=−1° C.), pentane (bp=35.9° C.), and various other refrigerant gases such as hydrofluorocarbons (HFCs). In an alternative embodiment of
Thus, as contemplated by the present invention, the apparatus of
In an alternative embodiment, the apparatus of
Reaction chamber 310 provides a controlled environment specifically intended to maintain the physical and chemical conditions conducive to the production of molecular diamond (i.e., the diamond unit cell) to yield useful, shapeable diamond masses that can be components of products or products themselves. As shown, work piece holder 340 supports deposition substrate 304. Although only one work piece holder 340, is shown, a plurality of work piece holders with associated deposition substrates in a single reaction chamber 310 can be accommodated by the present invention. Work piece holder 340 includes a means for locally controlling the temperature of the deposition substrate 304, the details for which are not shown. Temperature control lines 342 communicate data to and from the system controller 390 through sensor suite and interface 344, through sensor bus 345, main system bus 392, and controller bus 391. Sensor suite and interface 344, contains one or more temperature sensors and one or more pressure sensors. It can accommodate additional sensors. Although sensor suite and interface 344 is shown as a single, integrated module at one location in reaction chamber 310, alternatively, the sensors can be placed at disparate locations within the reaction chamber 310. Sensor suite and interface 344 communicates data to and from the system controller 390 through sensor bus 345, main system bus 392, and controller bus 391.
Additional sensors (not shown) can be provided exterior to reaction chamber 310 for monitoring the diamond production process as it proceeds. For example, various optical spectroscopy methods known in the art can be employed through optically transparent windows of the reaction chamber or through the transparent walls of a chamber that is constructed of glass and/or quartz or some other transparent material. Rate of diamond film growth can be monitored optically from outside the reaction chamber, as well. For example, ellipsometers, profilometers, and spectral reflectometers, all of which are commercially available and used in the semiconductor industry and others, can be used to measure geometric parameters of deposited diamond such as thickness and roughness (e.g. texture) and even optical and electrical properties of the synthesized diamond material.
Inlet port 384, provides for an inflow of inert gas 352 that is mixed with a vaporized form of a tetrahedranoidal molecule such as benzvalene, tetrahedranone, etc., obtained by controlled heating of the tetrahedranoidal molecule used (details not shown). Inert gas 352 flows into reaction chamber 310 transporting tetrahedranoidal molecule reactant vapor, and, as shown, may be pressurized by inlet pump 386 under the control of inlet pump control lines 388. Inlet pump 386 may be provided with dedicated flow sensor or sensors (preferably non-contact sensors) and/or pressure sensors that are not shown. Inlet pump control lines 388 communicate with system controller 390 through main system bus 392 and controller bus 391. It is also possible to maintain desired flow and pressure in reaction chamber 310 using the pressure of the gas storage tank and its regulator alone, making the inlet pump 386 unnecessary. Effluent leaves reaction chamber 310 through effluent port 360. As shown, effluent pump 362 controls flow of effluent from reaction chamber 310. There may be circumstances when effluent pump 362 is not used, and, thus, effluent exits reaction chamber 310 through effluent port 360 passively (e.g., due to the pressure) but through a controllable valve (not shown). Effluent pump 362 and inlet pump 386 operate in concert to maintain reaction chamber 310 pressure at less than ambient pressure when such is desired. Effluent pump 362 connects through to GC-MS 366 (gas chromatograph in tandem with a mass spectrometer), for effluent analysis.
Effluent pump 362 may be separate from or integrally a part of GC-MS 366. When separate from mass GC-MS 366, effluent pump 362 is controlled by the system controller 390 through effluent pump control lines 364. When integrally a part of GC-MS 366, effluent pump 362 may be directly or indirectly controlled through GC-MS bus 367, which connects communicatively through to system controller through main system bus 392 and controller bus 391. High-energy discharge module 368 can be a microwave or other appropriate high energy discharge device (e.g., RF radiation, laser radiation, electrostatic discharge, plasma, etc.) known in the bond cleavage art, which effects the decomposition of cubane to carbon atoms and free hydrogen atoms. It is switchable and under the control of system controller 390 through high energy discharge module control lines 374, which communicate with system controller 390 through main system bus 392 and controller bus 391. Discharge chamber 370 includes discharge antenna 372, which, as shown, can be a microwave waveguide or other wavelength RF antenna. In the case of a microwave high-energy discharge, discharge module 370 can be, effectively, provided with energy through a waveguide. As shown, a carbon source such as cubane vapor obtained by controlled heating in argon carrier gas 350 is transported through high-energy discharge module 370 via conduit 378. Carbon source flow control is a result of both carbon source vaporization control (details not shown) and argon carrier gas 350 flow, which is controlled by valve 380. Valve 380 is under the control of the systems controller 390 through valve control lines 382. Valve control lines 382 communicate with systems controller 390 through main system bus 392 and controller bus 391. Vaporization of the carbon source is mediated by the system controller. Within high-energy discharge module 368, the carbon source, such as cubane, is dissociated, under the influence of the high-energy discharge, into carbon atoms 316 in the inert carrier gas. This exits high-energy discharge module 370, through carbon conduit 376 and enters reactant delivery apparatus 312 through which it passes and is controllably directed at a predetermined location on deposition substrate 304. The relative position of delivery apparatus 312 is controlled by three dimensional position controller 394 (details not shown). Three dimensional position controller 394 is, in turn, controlled through position control lines 396, which communicate through to the systems controller 390 through main system bus 392 and controller bus 391. A single reaction chamber 310 can also accommodate multiple reactant delivery apparatuses.
If it is desired to use the apparatus of
Additional sensors (not shown) can be provided exterior to reaction chamber 410 for monitoring the diamond production process as it proceeds. For example, various optical spectroscopy methods known in the art can be employed through optically transparent windows of the reaction chamber or through the transparent walls of a chamber that is constructed of glass and/or quartz. Rate of diamond film growth can be monitored optically from outside the reaction chamber, as well. For example, ellipsometers, profilometers, and spectral reflectometers, all of which are commercially available and used in the semiconductor industry and others, can be used to measure geometric parameters of deposited diamond such as thickness and roughness (e.g. texture) and even optical and electrical properties of the synthesized diamond material.
Inlet port 484, provides for an inflow of inert gas 452a into reaction chamber 410 and, as shown, is pressurized by inlet pump 486 under the control of inlet pump control lines 488. Inlet pump 486 may be provided with dedicated flow sensor or sensors (preferably non-contact sensors) and/or pressure sensors that are not shown. Inlet pump control lines 488 communicate with system controller 490 through main system bus 492, and controller bus 491. It is also possible to maintain desired flow and pressure in reaction chamber 410 through the pressure of the gas storage tank and its regulator alone, making the inlet pump 486 unnecessary.
Effluent exits reaction chamber 410 through effluent port 460 either passively (e.g., through a controllable valve) or under control of effluent pump 462. Effluent pump 462 and inlet pump 486 operate in concert to maintain reaction chamber 410 pressure at less than, or more than, ambient pressure when such is desired. Effluent pump 462 connects through to GC-MS 466, for effluent analysis. Effluent pump 462 may be a separate from, or integrally a part of, GC-MS 466. When separate from GC-MS 466, effluent pump 462 is controlled by the system controller 490 through effluent pump control lines 464. When integrally a part of GC-MS 466, effluent pump 462 may be directly or indirectly controlled through mass spectrometer bus 467, which connects communicatively through to system controller through main system bus 492, and controller bus 491. High-energy discharge module 468 can be a microwave or other appropriate high energy discharge device (e.g., RF radiation, laser radiation, electrostatic discharge, plasma, etc.) known in the bond cleavage art, which effects the decomposition of cubane to carbon atoms and free hydrogen atoms. It is switchable and under the control of system controller 490 through high energy discharge module control lines 474, which communicate with system controller 490 through main system bus 492 and controller bus 491.
As shown in
The Control System
A detailed description of
A detailed description of
The control system of the apparatus embodiments of the present invention comprises a computer system in combination with hardware interfaces for sensor input data and output control signals for actuators. When lines are shown directly interfacing between a bus and a peripheral device such as a sensor, actuator, transducer, or valve, it should be assumed that the interfacing electronics is contained within the housing of the peripheral device. Control system software for the computer is designed with a modular structure, although other schemes are also possible. Process control can employ previously determined, preferred parameters that are stored in memory maps for use with process control strategies such as closed-loop, fuzzy logic, etc., which are commercially available. Generally, data are received from sensors in the apparatus and processed by the control system. When data indicate that a specific parameter's value has diverged from the desired set point, control signals are generated by the computer and routed through the control system interface to actuators of the apparatus. These signals correct for the difference between the actual measured parameter value and the target or desired value for that parameter.
Thus, for example, the internal temperature and pressure of the reaction chamber can be set to preferred values by adjusting the inert gas temperature and/or flow rate based on the data received from temperature and pressure sensors. The inert gas can be, for example, argon gas with less than three parts per million O2, which is commercially available. Thus, the gas entering the reaction chamber first passes through a refrigeration device that includes a pump and one or more heat exchangers. The temperature of the inert gas is controlled by varying the heat exchanger's refrigerant temperature, which is managed by the system controller. The reaction chamber temperature is measured by one or more temperature sensors and the temperature data are provided to the system controller. One temperature sensor can be placed on a wall of the reaction chamber. Another one or two can be placed on or near the gas input port or ports of the reaction chamber. Depending on the embodiment, temperature can also be measured with a temperature sensor disposed on or near the reactant nozzle or dispenser. If additional temperature control is desired, the work piece holder that holds the deposition substrate can be placed in intimate contact with a dedicated heat exchanger for heating and cooling the deposition substrate as required by the chosen process. Such a dedicated heat exchanger can have its own thermal fluid that is separate from that of the inert gas heat exchanger. Such apparatuses and their associated control systems are commercially available. The associated control system of the substrate heat exchanger is under the command and control of the general system controller.
The pressure in the reaction chamber can be controlled over a very wide range of values from fractions of an atmosphere up to many atmospheres. This is achieved by a combination of options that include using the high pressure of the inert gas in its storage cylinder or tank (passive pressure control) and/or an additional pressure pump in combination with a vacuum pump or controllable valve at the effluent port of the reaction chamber (active pressure control). Typically, when pressurized gas from a high pressure tank is provided to the reaction chamber, it flows through a gas pressure regulator, which provides a “step-down” in pressure as a first order of pressure control. Additional control is achieved through the use of a pressure sensor or sensors that are disposed within the reaction chamber. For example, one pressure sensor can be placed on the reaction chamber wall but local to the general deposition area. In the placement of sensors, care is taken to avoid undesired gas currents. If the reaction is performed at sub-atmospheric temperatures, a vacuum pump is used to maintain the lower pressure at the same time that inert gas continues to flow into the reaction chamber. If the reaction is performed above atmospheric pressures, passive pressure control (e.g., regulated tank pressure) and/or active pressure control (e.g., pump mediated) can be used. A valve can be used at the effluent port to control egress of the effluent gas.
Regardless of the pressure conditions chosen for a particular reaction, flow into, through, and out of the reaction chamber must be maintained. A controllable manifold can be used to provide kinetic energy to the gases to drive the molecular diamond forming reaction. By manipulating the gas regulator, inert gas pump, vacuum pump, and/or effluent valve based on temperature and pressure sensor data, the control system is able to set the preferred conditions for molecular diamond formation.
In vapor phase embodiments of the present invention, flow control may be achieved with a non-contact flow sensor or sensors (e.g., ultrasonic flow sensor) in the inert gas input port or ports of reaction chamber. For the embodiment of
The effluent port is attached to the input port of a GC-MS spectrometer, which generally has its own controllable pump system. The GC-MS spectrometer can monitor effluent either continually or periodically and provide effluent content data to the system controller. Process control may be based upon compositional data, physical parameter data, relative positional data, morphological data of the molecular diamond mass, etc. Mass spectrometer software is available both commercially and as open source programs that can be easily used in combination with the control system of the present invention.
Three-dimensional positioning of dispensers (e.g., automated pipetting systems), printing devices and other actuators, and control systems therefor, are well-developed technologies. A wide range of products for accomplishing the manufacturing processes shown in
The control system software for the present invention not only maintains preferred reaction conditions but also controls the proper sequence of events. For example, the switchable high-energy discharge apparatus can be actuated on and off depending on the effluent data provided by the mass spectrometer. The control system software can be written in a variety of programming languages, but particularly useful are languages that provide bit-level addressing and manipulation, such as C or C++, because these allow for easy interfacing with input and output ports (e.g., reading from or writing to A/D and D/A converters directly, respectively). Otherwise, interface routines can be coded in assembly language and control processing can be done in a higher level language. Alternatively, instrument control software development systems are available commercially (e.g., LabVIEW or LabWindows/CVI from National Instruments) that can be adapted to develop the control system software for the present invention.
The present invention as specified herein and as shown in the figures, can be used in variety of commercially valuable applications. The apparatuses can be adapted for onsite or field deposition of diamond onto substrates or work pieces such as cutting, abrading, or boring tool surfaces. For example, a portable apparatus is contemplated for oil field use where spent drill bits are remediated on site and re-coated with diamond. As another example, machine tools can be re-coated on the shop floor.
The present invention can also be used for stationary, large scale manufacturing in a factory or foundry environment. For example, the apparatus can be used to coat saw blades, razor blades, cutlery, drill and router bits, scalpels, and the like, as well as cooking equipment. The need for high purity nanodiamond particles in the pharmaceutical and cosmetics industries, as well as quantum computing devices, etc., can be met by the present invention.
Having described the present invention, it will be apparent to one skilled in the art that modifications and changes may be made to the above-described embodiments without departing from the spirit and scope of the present invention.
| Number | Date | Country | |
|---|---|---|---|
| 61344510 | Aug 2010 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 14713043 | May 2015 | US |
| Child | 15731940 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 14120508 | May 2014 | US |
| Child | 14713043 | US | |
| Parent | 13204218 | Aug 2011 | US |
| Child | 14120508 | US |
