The field relates generally to manifolds for vapor deposition, and, in particular, to manifolds for improving the quality of deposition in an atomic layer deposition (ALD) reactor.
There are several vapor deposition methods for depositing thin films on surfaces of substrates. These methods include vacuum evaporation deposition, Molecular Beam Epitaxy (MBE), different variants of Chemical Vapor Deposition (CVD) (including low-pressure and organometallic CVD and plasma-enhanced CVD), and Atomic Layer Deposition (ALD).
In an ALD process, one or more substrates with at least one surface to be coated are introduced into a deposition chamber. The substrate is heated to a desired temperature, typically above the condensation temperatures of the selected vapor phase reactants and below their thermal decomposition temperatures. One reactant is capable of reacting with the adsorbed species of a prior reactant to form a desired product on the substrate surface. Two, three or more reactants are provided to the substrate, typically in spatially and temporally separated pulses.
In an example, in a first pulse, a first reactant representing a precursor material is adsorbed largely intact in a self-limiting process on a wafer. The process is self-limiting because the vapor phase precursor cannot react with or adsorb upon the adsorbed portion of the precursor. After any remaining first reactant is removed from the wafer or chamber, the adsorbed precursor material on the substrate reacted with a subsequent reactant pulse to form no more than a single molecular layer of the desired material. The subsequent reactant may, e.g., strip ligands from the adsorbed precursor material to make the surface reactive again, replace ligands and leave additional material for a compound, etc. In an unadulterated ALD process, less than a monolayer is formed per cycle on average due to steric hindrance, whereby the size of the precursor molecules prevent access to adsorption sites on the substrate, which may become available in subsequent cycles. Thicker films are produced through repeated growth cycles until the target thickness is achieved. Growth rate is often provided in terms of angstroms per cycle because in theory the growth depends solely on number of cycles, and has no dependence upon mass supplied or temperature, as long as each pulse is saturative and the temperature is within the ideal ALD temperature window for those reactants (no thermal decomposition and no condensation).
Reactants and temperatures are typically selected to avoid both condensation and thermal decomposition of the reactants during the process, such that chemical reaction is responsible for growth through multiple cycles. However, in certain variations on ALD processing, conditions can be selected to vary growth rates per cycle, possibly beyond one molecular monolayer per cycle, by utilizing hybrid CVD and ALD reaction mechanisms. Other variations maybe allow some amount of spatial and/or temporal overlap between the reactants. In ALD and other sequential vapor deposition variations thereof, two, three, four or more reactants can be supplied in sequence in a single cycle, and the content of each cycle can be varied to tailor composition.
During a typical ALD process, the reactant pulses, all of which are in vapor form, are pulsed sequentially into a reaction space (e.g., reaction chamber) with removal steps between reactant pulses to avoid direct interaction between reactants in the vapor phase. For example, inert gas pulses or “purge” pulses can be provided between the pulses of reactants. The inert gas purges the chamber of one reactant pulse before the next reactant pulse to avoid gas phase mixing. To obtain a self-limiting growth, a sufficient amount of each precursor is provided to saturate the substrate. As the growth rate in each cycle of a true ALD process is self-limiting, the rate of growth is proportional to the repetition rate of the reaction sequences rather than to the flux of reactant.
In one aspect, a semiconductor processing device is provided which includes: a manifold including: a bore configured to deliver a gas to a reaction chamber; a first block mounted to a second block, the first and second mounted blocks cooperating to at least partially define the bore; and a supply channel that provides fluid communication between a gas source and the bore, the supply channel disposed at least partially in the second block. The semiconductor processing device further includes a metallic seal disposed about the bore at an interface between the first and second block.
In some embodiments, the metallic seal is a C seal. The metallic seal can be steel. In some embodiments, the metallic seal can be a W seal. The semiconductor processing device may further include an outlet at a lower portion of the manifold. The supply channel may be angled upwardly away from the outlet and inwardly towards the bore. The first block may include an impingement surface at an upper portion of the manifold, the impingement surface shaped to redirect gas downwardly through the bore to the outlet. The impingement surface and the outlet may be disposed along a longitudinal axis of the bore.
In some embodiments, the semiconductor processing device further includes an insulator cap. The insulator cap may comprise Polytetrafluoroethylene (PTFE) and at least two pieces of members configured to surround the first block. A plurality of heater rods may be arranged in the second block.
In some embodiments, the semiconductor processing device further includes a third block mounted to and below the second block, a second metallic seal between the second and third blocks and at least partially disposed about the bore, where the second and third blocks cooperate to at least partially define the bore. The outlet may be at least partially defined by the third block.
In some embodiments, the second block may comprise a heater rod arranged in the second block. The second block may be configured to accommodate the heater rod extending all the way to the first block to heat the manifold entirely.
In some embodiments, the semiconductor processing device further includes a gas dispersion device downstream of the outlet, the gas dispersion device configured to disperse a flow of the gas into a reaction chamber. The semiconductor processing device may further include the reaction chamber downstream of the gas dispersion device, the reaction chamber configured to receive a substrate. In some embodiments, the semiconductor processing device further includes a valve block mounted to the second block and a second metallic seal disposed between the valve block and the first block, a reactant gas valve mounted to or coupled with the valve block.
In some embodiments, the semiconductor processing device may comprise at least three valve blocks mounted to the second block. Each valve block may be mounted to respective side surfaces of the second block and two of the at least three valve blocks are mounted on the side surfaces opposite to each other being located in a same distance from the impingement surface. One of the at least three valve blocks is mounted closer to the impingement surface than the two of the three valve blocks mounted on the side surfaces opposite to each other.
In another aspect, a semiconductor processing device is provided which includes: a manifold comprising: a bore configured to deliver a gas to a reaction chamber and an impingement surface at an upper portion of the manifold. The semiconductor processing device further includes an outlet at a lower portion of the manifold and a supply channel that provides fluid communication between a gas source and the bore, the supply channel is angled upwardly away from the outlet and inwardly towards the bore, the supply channel oriented to direct gas upwardly towards the impingement surface, and the impingement surface is shaped to redirect gas downwardly through the bore to the outlet. The semiconductor processing device may also comprise an insulator cap mounted to the upper portion of the manifold, the insulator cap comprising a thermally insulating material. The insulator cap may comprise at least two pieces of members comprising Polytetrafluoroethylene (PTFE), which may be configured to surround the upper portion of the manifold. A plurality of heater rods may be arranged in the manifold extending at least partially through the upper portion of the manifold.
In some embodiments, the manifold includes a first block mounted to a second block, the first and second mounted blocks cooperating to at least partially define the bore, the first block includes the impingement surface. The semiconductor processing device may further include a metallic seal disposed at least partially about the bore between the first and second blocks. The impingement surface and the outlet may be disposed along a longitudinal axis of the bore. The semiconductor processing device may further include a showerhead below the outlet, the showerhead configured to laterally disperse a flow of the gas. The semiconductor processing device may further include a reaction chamber below the showerhead, the reaction chamber configured to receive a substrate. In some embodiments, the outlet opens without restriction into a reaction chamber configured to house one or more substrates.
These and other features, aspects and advantages of the present invention will now be described with reference to the drawings of several embodiments, which embodiments are intended to illustrate and not to limit the invention.
The embodiments disclosed herein can be utilized with semiconductor processing devices configured for any suitable gas or vapor deposition process, including processes that alternate reactant exposures (e.g., pulses) to the substrate. For example, the illustrated embodiments show various systems for depositing material on a substrate using atomic layer deposition (ALD) techniques. Among vapor deposition techniques, ALD has many advantages, including high conformality at low temperatures and fine control of composition during the process. ALD type processes are based on controlled, self-limiting surface reactions of precursor chemicals. Gas phase reactions are avoided by feeding the precursors alternately and sequentially into the reaction chamber. Vapor phase reactants are separated from each other in the reaction chamber, for example, by removing excess reactants and/or reactant by-products from the reaction chamber between reactant pulses. Removal can be accomplished by a variety of techniques, including purging and/or lowering pressure between pulses. Pulses can be sequential in a continuous flow, or the reactor can be isolated and can backfilled for each pulse. Of course, the equipment disclosed herein can be useful for other vapor deposition processes, particularly those in which alternation of reactants is desired, such that processes employed by the equipment may include some degree of thermal decomposition and/or overlap of precursor spatially or temporally.
Briefly, a substrate is loaded into a reaction chamber and is heated to a suitable deposition temperature, generally at lowered pressure. Deposition temperatures are typically maintained below the precursor thermal decomposition temperature but at a high enough level to avoid condensation of reactants and to provide the activation energy for the desired surface reactions. Of course, the appropriate temperature window for any given ALD reaction will depend upon the surface termination and reactant species involved, and processes that allow for either condensation or thermal decomposition can be conducted with equipment described herein.
A first reactant is conducted into the chamber in the form of vapor phase pulse and contacted with the surface of a substrate. Conditions are preferably selected such that no more than about one monolayer of the precursor is adsorbed on the substrate surface in a self-limiting manner. Excess first reactant and reaction byproducts, if any, are purged from the reaction chamber, often with a pulse of inert gas such as nitrogen or argon.
Purging the reaction chamber means that vapor phase precursors and/or vapor phase byproducts are removed from the reaction chamber such as by evacuating the chamber with a vacuum pump and/or by replacing the gas inside the reactor with an inert gas such as argon or nitrogen. Typical purging times for a single wafer reactor are from about 0.05 to 20 seconds, particularly between about 1 and 10 seconds, and still more particularly between about 1 and 2 seconds. However, other purge times can be utilized if desired, such as when depositing layers over extremely high aspect ratio structures or other structures with complex surface morphology is needed, or when a high volume batch reactor is employed. The appropriate pulsing times can be readily determined by the skilled artisan based on the particular circumstances.
A second gaseous reactant is pulsed into the chamber where it reacts with the first reactant bound to the surface. Excess second reactant and gaseous by-products of the surface reaction are purged out of the reaction chamber, preferably with the aid of an inert gas. The steps of pulsing and purging are repeated until a thin film of the desired thickness has been formed on the substrate, with each cycle leaving no more than a molecular monolayer. Some ALD processes can have more complex sequences with three or more precursor pulses alternated, where each precursor contributes elements to the growing film. Reactants can also be supplied in their own pulses or with precursor pulses to strip or getter adhered ligands and/or free by-product, rather than contribute elements to the film. Additionally, not all cycles need to be identical. For example, a binary film can be doped with a third element by infrequent addition of a third reactant pulse, e.g., every fifth cycle, in order to control stoichiometry of the film, and the frequency can change during the deposition in order to grade film composition. Moreover, while described as starting with an adsorbing reactant, some recipes may start with the other reactant or with a separate surface treatment, for example to ensure maximal reaction sites to initiate the ALD reactions (e.g., for certain recipes, a water pulse can provide hydroxyl groups on the substrate to enhance reactivity for certain ALD precursors).
As mentioned above, each pulse or phase of each cycle is preferably self-limiting for ALD reactions. An excess of reactant precursors is supplied in each phase to saturate the susceptible structure surfaces. Surface saturation ensures reactant occupation of all available reactive sites (subject, for example, to physical size or steric hindrance restraints) and thus ensures excellent step coverage over any topography on the substrate. In some arrangements, the degree of self-limiting behavior can be adjusted by, e.g., allowing some overlap of reactant pulses to trade off deposition speed (by allowing some CVD-type reactions) against conformality. Ideal ALD conditions with reactants well separated in time and space provide near perfect self-limiting behavior and thus maximum conformality, but steric hindrance results in less than one molecular layer per cycle. Limited CVD reactions mixed with the self-limiting ALD reactions can raise the deposition speed. While embodiments described herein are particularly advantageous for sequentially pulsed deposition techniques, like ALD and mixed-mode ALD/CVD, the manifold can also be employed for pulsed or continuous CVD processing. Many kinds of reactors capable of ALD growth of thin films, including CVD reactors equipped with appropriate equipment and means for pulsing the precursors, can be employed. In some embodiments a flow type ALD reactor is used, as compared to a backfilled reactor. In some embodiments, the manifold is upstream of an injector designed to distribute gas into the reaction space, particularly a dispersion mechanism such as a showerhead assembly above a single-wafer reaction space.
Many kinds of reactors capable of ALD growth of thin films, including CVD reactors equipped with appropriate equipment and means for pulsing the precursors, can be employed. In some embodiments a flow type ALD reactor is used, as compared to a backfilled reactor. In some embodiments, the manifold is upstream of an injector designed to distribute gas into the reaction space, particularly a dispersion mechanism such as a showerhead assembly above a single-wafer reaction space.
The ALD processes can optionally be carried out in a reaction chamber or space connected to a cluster tool. In a cluster tool, because each reaction space is dedicated to one type of process, the temperature of the reaction space in each module can be kept constant, which improves the throughput compared to a reactor in which is the substrate is heated to the process temperature before each run. A stand-alone reactor can be equipped with a load-lock. In that case, it is not necessary to cool down the reaction chamber or space between each run.
These processes can also be carried out in a reactor designed to process multiple substrates simultaneously, e.g., a mini-batch type showerhead reactor.
Various embodiments disclosed herein relate to a semiconductor device, such as a vapor deposition device (e.g., an ALD device, a CVD device, etc.), that includes a manifold for delivering reactant vapor(s) to a reaction chamber. Regardless of the natural state of the chemicals under standard conditions, the reactant vapors may be referred to as “gases” herein. The embodiments disclosed herein can beneficially provide an effective fluid seal for the bore of the manifold. For example, in various embodiments, metallic seals (e.g., C seals) can be provided between adjacent blocks to inhibit the flow of gas (e.g., air) from the outside environs into the manifold. Moreover, the embodiments disclosed herein can provide an extended mixing length by, e.g., directing reactant gas upwardly through the supply channels at an angle and directing the reactant gases back downwardly through the bore. The disclosed embodiments can accordingly provide improved sealing, extended mixing length, and reduced non-uniformities at the substrate.
The manifold 100 can include the manifold body 102 connected with valve blocks 112a, 112b, shown on opposite sides of the manifold body 102. Reactant valves and inert gas valves (not shown) are disposed on the blocks 112a, 112b, or on other upstream blocks (not shown). An inert gas inlet 120 can supply inert gas to the manifold 100, for example, from an upper portion of the manifold 100. The manifold body 102 comprises multiple blocks stacked on one another to at least partially define a bore 130 along which gas(es) flow, including, for example, an upper block 104, an intermediate block 106, and a lower block 108. In the arrangement of
Although the arrangement of
Moreover, as explained in more detail below in connection with
Supply lines 138a-138c can be provided to supply gas from corresponding gas distribution channels to the bore 130. Unlike the embodiment of
The bore 130 of the manifold body 102 can deliver reactant and/or inactive gases to a reaction chamber 30 of a reactor 21 by way of the outlet 132 at the bottom of the manifold body 102. A dispersion device 35, such as a showerhead as shown, or a horizontal injection device in other embodiments, can include a plenum 32 in fluid communication with a plurality of openings 19. The reactant vapor can pass through the openings 19 and be supplied into the reaction chamber 30. A substrate support 22 can be configured, or sized and shaped, to support a substrate 36, such as a wafer, within the reaction chamber 30. The dispersed reactant vapor can contact the substrate and react to form a layer (e.g., a monolayer) on the substrate. The dispersion device 35 can disperse the reactant vapor in a manner so as to form a uniform layer on the substrate.
An exhaust line 23 can be in fluid communication with the reaction chamber 30. A vacuum pump 24 can apply suction to the exhaust line 23 to evacuate vapors and excess materials from the reaction chamber 30. The reactor 21 can comprise any suitable type of semiconductor reactor, such as an atomic layer deposition (ALD) device, a chemical vapor deposition (CVD) device, etc. Moreover, the device 10 can comprise a control system 34 in electronic and data communication with the reactor 21. The control system 34 can comprise one or a plurality of processors configured to control the operation of the device 10. Additional components may be provided to manage the operation of the device 10.
Beneficially, the use of the upwardly angled supply channels 138a-138c and the impingement surface 214 can provide an extended mixing length along which gases can become uniformly mixed. Moreover, the extended mixing length provided by the channels 138a-138c can reduce the effects of “throw” or spiral/helical flow effect that may result when the curved pathway 180 of
Also, in
In the arrangement of
Turning to
During inspection on some reaction chambers 30 after use, white powder has been observed on an upper portion 109 (see
Cold spots may cause poor film formation such that deposited films may be delaminated after only a small amount of accumulation. Moreover, diffusion and/or backflow into the gas lines may result in particle accumulation on the wafer and can cause early chamber failure. The cold spots can be detected on the upper portion 109 which has been measured to be approximately 40° C. lower (depending on temperature set point) compared to the rest of manifold body 102. Accordingly, there remains a continuing need for improved thermal management of semiconductor processing devices. In some embodiments disclosed herein, active heating and/or insulation can be provided on an upper portion 109 of the manifold 100.
Unless otherwise noted, the embodiments of
As shown in the embodiment of
Further, as shown in
In order to eliminate the response lag between reactant valves 116a, 116b mounted on the valve block 112a, 112b, and the third reactant valve 116c, as shown in
Although the foregoing has been described in detail by way of illustrations and examples for purposes of clarity and understanding, it is apparent to those skilled in the art that certain changes and modifications may be practiced. Therefore, the description and examples should not be construed as limiting the scope of the invention to the specific embodiments and examples described herein, but rather to also cover all modification and alternatives coming with the true scope and spirit of the invention. Moreover, not all of the features, aspects and advantages described herein above are necessarily required to practice the present invention.
This application is a continuation-in-part of U.S. application Ser. No. 16/813,527, filed on Mar. 9, 2020, now granted, which claims the benefit of priority to U.S. Provisional Application No. 62/820,711, filed Mar. 19, 2019, titled REACTOR MANIFOLDS, the contents of each of which are hereby incorporated by reference herein in their entirety.
Number | Date | Country | |
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62820711 | Mar 2019 | US |
Number | Date | Country | |
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Parent | 16813527 | Mar 2020 | US |
Child | 18045419 | US |