Decaborane ionizer

Information

  • Patent Grant
  • 6288403
  • Patent Number
    6,288,403
  • Date Filed
    Monday, October 11, 1999
    25 years ago
  • Date Issued
    Tuesday, September 11, 2001
    23 years ago
Abstract
An ion source (50) for an ion implanter is provided, comprising a remotely located vaporizer (51) and an ionizer (53) connected to the vaporizer by a feed tube (62). The vaporizer comprises a sublimator (52) for receiving a solid source material such as decaborane and sublimating (vaporizing) the decaborane. A heating mechanism is provided for heating the sublimator, and the feed tube connecting the sublimator to the ionizer, to maintain a suitable temperature for the vaporized decaborane. The ionizer (53) comprises a body (96) having an inlet (119) for receiving the vaporized decaborane; an ionization chamber (108) in which the vaporized decaborane may be ionized by an energy-emitting element (110) to create a plasma; and an exit aperture (126) for extracting an ion beam comprised of the plasma. A cooling mechanism (100, 104) is provided for lowering the temperature of walls (128) of the ionization chamber (108) (e.g., to below 350° C.) during ionization of the vaporized decaborane to prevent dissociation of vaporized decaborane molecules into atomic boron ions. In addition, the energy-emitting element is operated at a sufficiently low power level to minimize plasma density within the ionization chamber (108) to prevent additional dissociation of the vaporized decaborane molecules by the plasma itself.
Description




FIELD OF THE INVENTION




The present invention relates generally to ion sources for ion implantation equipment and more specifically to an ion source for ionizing decaborane.




BACKGROUND OF THE INVENTION




Ion implantation has become a standard accepted technology of industry to dope workpieces such as silicon wafers or glass substrates with impurities in the large scale manufacture of items such as integrated circuits and flat panel displays. Conventional ion implantation systems include an ion source that ionizes a desired dopant element which is then accelerated to form an ion beam of prescribed energy. The ion beam is directed at the surface of the workpiece to implant the workpiece with the dopant element. The energetic ions of the ion beam penetrate the surface of the workpiece so that they are embedded into the crystalline lattice of the workpiece material to form a region of desired conductivity. The implantation process is typically performed in a high vacuum process chamber which prevents dispersion of the ion beam by collisions with residual gas molecules and which minimizes the risk of contamination of the workpiece by airborne particulates.




Ion dose and energy are the two most important variables used to define an implant step. Ion dose relates to the concentration of implanted ions for a given semiconductor material. Typically, high current implanters (generally greater than 10 milliamps (mA) ion beam current) are used for high dose implants, while medium current implanters (generally capable up to about 1 mA beam current) are used for lower dose applications. Ion energy is used to control junction depth in semiconductor devices. The energy of the ions which make up the ion beam determine the degree of depth of the implanted ions. High energy processes such as those used to form retrograde wells in semiconductor devices require implants of up to a few million electron volts (MeV), while shallow junctions may only demand energies below 1 thousand electron volts (keV).




The continuing trend to smaller and smaller semiconductor devices requires implanters with ion sources that serve to deliver high beam currents at low energies. The high beam current provides the necessary dosage levels, while the low energy levels permit shallow implants. Source/drain junctions in complementary metal-oxide-semiconductor (CMOS) devices, for example, require such a high current, low energy application.




A typical ion source


10


for obtaining atoms for ionization from a solid form is shown in FIG.


1


. The ion source comprises a pair of vaporizers


12


and


14


and an ionization chamber


16


. Each of the vaporizers is provided with a crucible


18


in which a solid element or compound is placed and which is heated by a heater coil


20


to vaporize the solid source material. Heater coil leads


22


conduct electrical current to the heater coils and thermocouples


24


provide a temperature feedback mechanism. Air cooling conduit


26


and water-cooling conduit


28


is also provided.




Vaporized source material passes through a nozzle


30


, which is secured to the crucible


18


by a graphite nozzle retainer


32


, and through vaporizer inlets


34


to the interior of the ionization chamber


16


. Alternatively, compressed gas may be fed directly into the ionization chamber by means of a gas inlet


36


via a gas line


38


. In either case, the gaseous/vaporized source material is ionized by an arc chamber filament


40


that is heated to thermionically emit electrons.




Conventional ion sources utilize an ionizable dopant gas which is obtained either directly from a source of a compressed gas or indirectly from a solid which has been vaporized. Typical source elements are boron (B), phosphorous (P), gallium (Ga), indium (In), antimony (Sb), and arsenic (As). Most of these source elements are commonly used in both solid and gaseous form, except boron, which is almost exclusively provided in gaseous form, e.g., as boron trifluoride (BF


3


).




In the case of implanting boron trifluoride, a plasma is created which includes singly charged boron (B+) ions. Creating and implanting a sufficiently high dose of boron into a substrate is usually not problematic if the energy level of the beam is not a factor. In low energy applications, however, the beam of boron ions will suffer from a condition known as “beam blow-up”, which refers to the tendency for like-charged ions within the ion beam to mutually repel each other. Such mutual repulsion causes the ion beam to expand in diameter during transport, resulting in vignetting of the beam by multiple apertures in the beamline. This severely reduces beam transmission as beam energy is reduced.




Decaborane (B


10


H


14


) is a compound which is an excellent source of feed material for boron implants because each decaborane molecule (B


10


H


14


) when vaporized and ionized can provide a molecular ion comprised of ten boron atoms. Such a source is especially suitable for high dose/low energy implant processes used to create shallow junctions, because a molecular decaborane ion beam can implant ten times the boron dose per unit of current as can a monatomic boron ion beam. In addition, because the decaborane molecule breaks up into individual boron atoms of roughly one-tenth the original beam energy at the workpiece surface, the beam can be transported at ten times the energy of a dose-equivalent monatomic boron ion beam. This feature enables the molecular ion beam to avoid the transmission losses that are typically brought about by low energy ion beam transport.




However, decaborane ion sources to date have been unsuccessful at generating sufficient ion beam current for production applications of boron implants. Known hot-cathode sources are unsuitable for decaborane ionization because the heat generated by the cathode and arc in turn heats the walls and components to greater than 500° C., causing dissociation of the decaborane molecule into borane fragments and elemental boron. Known plasma-based sources are unsuitable for decaborane ionization because the plasma itself can cause dissociation of the decaborane molecule and fragmentation of the B


10


H


X




+


desired parent ion. Accordingly, in known decaborane ion sources, the source chamber pressure is kept sufficiently low to prevent the sustenance of a local plasma. Thus far, ion beam currents developed from such a source are too low for production applications.




Accordingly, it is an object of the present invention to provide an ion source for an ion implanter, which can accurately and controllably ionize sufficient decaborane to produce acceptable production ion beam current levels, to overcome the deficiencies of known ion sources.




SUMMARY OF THE INVENTION




An ion source for an ion implanter is provided, comprising a vaporizer and a remotely located ionizer connected to the vaporizer by a feed tube. The vaporizer comprises a sublimator for receiving a solid source material such as decaborane and sublimating (vaporizing) the decaborane. A heating mechanism is provided for heating the sublimator, and the feed tube connecting the sublimator to the ionizer, to maintain a suitable temperature for the vaporized decaborane.




The ionizer comprises a body having an inlet for receiving the vaporized decaborane; an ionization chamber in which the vaporized decaborane may be ionized by an energy-emitting element to create a plasma; and an exit aperture for extracting an ion beam comprised of the plasma. A cooling mechanism is provided for lowering the temperature of walls of the ionization chamber (e.g., to below 350° C.) during the ionization of the vaporized decaborane to prevent dissociation of vaporized decaborane molecules into atomic boron ions. In addition, the energy-emitting element is operated at a sufficiently low power level to minimize plasma density within the ionization chamber to prevent additional dissociation of the vaporized decaborane molecules by the plasma itself











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a perspective, partially cross sectional view of a conventional ion source for an ion implanter;





FIG. 2

is a schematic, partially cross sectional view of a first embodiment of an ion source for an ion implanter constructed according to the principles of the present invention;





FIG. 3

is a cross sectional view of a connecting tube of an alternative embodiment of the ion source of

FIG. 2

, taken along the lines


3





3


; and





FIG. 4

is a partially cross sectional view of the ionizer portion of the ion source of FIG.


2


.











DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION




Referring now to

FIGS. 2-4

of the drawings, and initially to

FIG. 2

, an ion source


50


comprising a vaporizer


51


and an ionizer


53


are shown, constructed according to the present invention. The vaporizer


51


comprises a non-reactive, thermally conductive sublimator or crucible


52


, a heating medium reservoir


54


, a heating medium pump


55


, a temperature controller


56


, and a mass flow controller


60


. Ionizer


53


is shown in more detail in FIG.


3


. The crucible


52


is located remotely from the ionizer


53


and connected thereto by a feed tube


62


, constructed of quartz or stainless steel. In the disclosed embodiment, the feed tube


62


is surrounded by an outer single-chamber annular sheath


90


along substantially the entire length thereof.




The crucible


52


provides a container


64


enclosing a cavity


66


for containing a source material


68


. The container is preferably made of a suitable non-reactive (inert) material such as stainless steel, graphite, quartz or boron nitride and which is capable of holding a sufficient amount of source material such as decaborane (B


10


H


14


). Although the invention is described further below only in terms of decaborane, it is contemplated that the principles of the present invention may be used for other molecular solid source materials, such as indium trichloride (InCl


3


), which are characterized as having both low melting points (i.e., sublimation temperatures of between 20° C. and 250° C.) and significant room temperature vapor pressures (i.e. between 10


−2


Torr and 10


3


Torr).




The decaborane is vaporized through a process of sublimation by heating the walls of the container


64


with a heating medium


70


contained in reservoir


54


. A wire mesh


71


prevents non-vaporized decaborane from escaping the crucible


52


. Completely vaporized decaborane exits the crucible


52


via feed tube


62


and enters mass flow controller


60


, which controls the flow of vapor, and thus meters the amount of vaporized decaborane which is provided to the ionizer


53


, as is known in the art.




Alternatively, in a second embodiment of the invention, the feed tube


62


is provided in the form of a capillary tube and sheath


90


is provided in the form of a coaxial dual-chamber sheath, comprising an inner sheath


90


A surrounded by an outer sheath


90


B (see FIG.


3


). The heating medium may be pumped into the inner sheath


90


A (located adjacent the capillary tube


62


) and pumped out of the outer sheath


90


B (located radially outward from the inner sheath


90


A). In this second embodiment, the mass flow controller


60


is replaced with a heated shut-off valve (not shown) located at the feed tube/ionizer interface, and mass flow is increased or decreased by directly changing the temperature of the reservoir


54


. Alternatively, a separate heat source may be provided for the shut-off valve. The arrangement of the coaxial sheath surrounding the capillary tube has the advantage of providing an insulating sheath surrounding the inner diameter of the capillary tube, thereby resulting in a more uniform temperature.




The ionizer


53


is shown in more detail in FIG.


4


. The ionizer


53


comprises a generally cylindrical body


96


and a generally annular base or mounting flange


98


, both in the preferred embodiment constructed of aluminum. Aluminum does not pose significant contamination problems. The body


96


is preferably constructed of a single machined piece of aluminum to facilitate water cooling as described below. In addition, aluminum provides good thermal conductivity.




The aluminum body


96


is cooled by means of entry cooling passageway


100


fed by inlet


102


and exit cooling passageway


104


which exits body


96


via outlet


106


. The cooling medium may be water or any other suitable fluid having high heat capacity. The entry and exit cooling passageways provide a continuous pathway by which water flows therethrough to cool the ionizer body


96


. Although only a fragmented portion of the pathway is shown in phantom in

FIG. 4

, the pathway may extend near and about the outer periphery of the body in any known configuration to insure that the entire body is effectively cooled. By cooling the body


96


, an ionization chamber


108


within the ionizer


53


may be maintained at a temperature low enough (less than 350° C.) to prevent dissociation of the ionized decaborane molecule.




Within the confines of the ionizer body


96


are an extension of the feed tube


62


, surrounded by annular sheath


90


, terminating at ionization chamber


108


. Within the ionization chamber reside a hot cathode


110


and an anti-cathode or repeller


112


. The hot cathode


110


comprises a heated filament


114


surrounded by a cylinder


116


and capped by endcap


118


. In the preferred embodiment, the filament and the endcap are made of tungsten, and the cylinder is made of molybdenum. The heated filament


114


is energized via power feedthroughs


120


and


122


that pass through and are electrically insulated from the aluminum body


96


. The repeller


112


is also electrically insulated from the body


96


, via a thermally conductive electrically insulating material (such as sapphire) which physically couples the repeller to the cooled ionization chamber


108


.




In operation, the vaporized material is injected into the ionization chamber via feed tube


62


at ionizer inlet


119


. When the tungsten filament


114


is energized electrically by application of a potential difference across feedthroughs


120


and


122


, the filament emits electrons that accelerate toward and impact endcap


118


. When the endcap


118


is sufficiently heated by electron bombardment, it in turn emits electrons into the ionization chamber


108


that strike the vaporized gas molecules to create ions in the chamber.




A low-density ion plasma is thereby created, from which an ion beam is extracted from the chamber through source aperture


126


. The low density of the plasma in chamber


108


is in part provided by the relatively low arc discharge power maintained in the source (about 5 watts (W) at 50 milliamps (mA)). The endcap


118


shields the filament


114


from contact with the low-density plasma and thereby extends the lifetime of the filament. The indirectly heated cathode arrangement shown in

FIG. 4

may be replaced by other conventional source devices, for example simple filaments as used in Freeman-type or Bernas-type ion sources.




Electrons generated by cathode


110


which do not strike a decaborane molecule in the ionization chamber to create a decaborane ion move toward the repeller


112


, which deflects these electrons back toward the cathode. The repeller is preferably constructed of molybdenum and, like the cathode, is electrically insulated from the ionizer body


96


. The repeller may be water-cooled if it is found that minimal decaborane molecule dissociation is being caused by the repeller (or physically coupled to the body


96


using an electrical insulator with high thermal conductivity).




Walls


128


of the ionization chamber


108


are maintained at local electrical ground potential. The cathode


110


, including endcap


118


, is maintained at a potential of approximately 50 to 150 volts below the potential of the walls


128


. The filament


114


is maintained at a voltage approximately between 200 and 600 volts below the potential of the endcap


118


. The large voltage difference between the filament


114


and the endcap


118


imparts a high energy to the electrons emitted from the filament to sufficiently heat endcap


118


to thermionically emit electrons into the ionization chamber


108


.




Alternatively, instead of the cathode/repeller combination shown in

FIG. 4

, an RF exciter (not shown) such as an antenna may be energized to emit an RF signal that ionizes the vaporized decaborane molecules in the chamber


108


to create a plasma. The power associated with such an RF antenna is on the order of 40W-50W. A magnetic filter (not shown) also disposed within the chamber


108


filters the plasma, and extractor electrodes (not shown) located outside source aperture


126


extract the plasma from the ionization chamber as is known in the art. Alternatively still, microwave energy may be directed from a microwave source to the ionization chamber


108


to ionize the vaporized decaborane molecules to create a plasma.




The inventive ion source


50


provides a control mechanism for controlling the operating temperature of the crucible


52


, as well as that of the feed tube


62


through which vaporized decaborane passes on its way to and through the ionizer


53


. The heating medium


70


is heated within the reservoir


54


by a resistive or similar heating element


80


and cooled by a heat exchanger. The temperature control means comprises a temperature controller


56


which obtains as an input temperature feedback from the reservoir


54


via thermocouple


92


, and outputs a control signal to heating element


80


, as further described below, so that the heating medium


70


in the reservoir is heated to a suitable temperature. The operating temperature control mechanism for heating the both the vaporizer


51


and the feed tube in the ionizer


53


may be provided by a single circuit, as shown in

FIGS. 2 and 4

. Alternatively, separate temperature control circuits may be provided for the vaporizer


51


and the ionizer


53


.




The heating medium


70


comprises mineral oil or other suitable medium (e.g., water) that provides a high heat capacity. The oil is heated to a temperature within the 20° C. to 250° C. range by the heating element


80


and circulated by pump


55


around the crucible


52


and the feed tube


62


through sheath


90


. The pump


55


is provided with an inlet and an outlet


82


and


84


, respectively, and the reservoir


54


is similarly provided with an inlet


86


and an outlet


88


, respectively. The flow pattern of the heating medium about the crucible


52


and the feed tube


62


, although shown in a unidirectional clockwise pattern in

FIG. 2

, may be any pattern that provides reasonable circulation of the medium about the crucible


52


and the feed tube


62


.




Referring back to

FIG. 2

, the crucible cavity


66


is pressurized in order to facilitate material transfer of the vaporized (sublimated) decaborane from the crucible


52


to the ionization chamber


108


through the feed tube


62


. As the pressure within cavity


66


is raised, the rate of material transfer correspondingly increases. The ionization chamber operates at a near vacuum (about 1 millitorr), and thus, a pressure gradient exists along the entire length of the feed tube


62


, from the crucible


52


to the ionization chamber


108


. The pressure of the crucible is typically on the order of 1 torr.




By locating the crucible


52


remotely from the ionization chamber


108


, the material within crucible cavity


66


is thermally isolated, thereby providing a thermally stable environment unaffected by the temperature in the ionization chamber. As such, the temperature of the crucible cavity


66


, in which the process of decaborane sublimation occurs, may be controlled independently of the operating temperature of the ionization chamber


108


to a high degree of accuracy (within 1° C.). Also, by maintaining a constant temperature of the vaporized decaborane during transport to the ionization chamber via the heated feed tube


62


, no condensation or thermal decomposition of the vapor occurs.




The temperature controller


56


controls the temperature of the crucible


52


and the feed tube


62


by controlling the operation of the heating element


80


for the heating medium reservoir


70


. Thermocouple


92


senses the temperature of the reservoir


70


and sends temperature feedback signal


93


to the temperature controller


56


. The temperature controller responds to this input feedback signal in a known manner by outputting control signal


94


to the reservoir heating element


80


. In this manner, a uniform temperature is provided for all surfaces to which the solid phase decaborane and vaporized decaborane are exposed, up to the location of the ionization chamber.




By controlling the circulation of the heating medium in the system (via pump


55


) and the temperature of the heating medium (via heating element


80


), the ion source


50


can be controlled to an operating temperature of on the order of 20° C. to 250° C. (+/−1° C.). Precise temperature control is more critical at the crucible, as compared to the end of the feed tube nearest the ionization chamber, to control the pressure of the crucible and thus the vapor flow rates out of the crucible.




Because the plasma density using the inventive source is kept low (on the order 10


10


/cm


3


) to prevent dissociation of the decaborane molecule, total extracted ion beam current will be low when using a conventionally-sized source aperture. Assuming a comparable beam current density, the aperture


126


in the ionizer


53


of the present invention is made large enough to insure an adequate ion beam current output. A 1 cm


2


(0.22 cm×4.5 cm) aperture permits a beam current density of about 100 microamps per square centimeter (μA/cm


2


) at the workpiece (i.e., 1 μA), and up to (less than or equal to) 1 mA/cm


2


of extracted beam current from the source (i.e., 1 mA). (The actual focused beam current delivered to the workpiece is only a fraction of the total extracted beam current.) Aperture sizes of about 5 cm


2


are possible in some implanters, which would yield a B


10


H


X


N


+


beam current of about 500 μA at the workpiece. In ultra low energy (ULE) implanters, even larger aperture sizes (up to 13 cm


2


) are possible.




Using either embodiment of the source


50


of

FIG. 2

in an ion implanter, an entire molecule (ten boron atoms) is implanted into the workpiece. The molecule breaks up at the workpiece surface such that the energy of each boron atom is roughly one-tenth the energy of the ten-boron cluster (in the case of B


10


H


14


). Thus, the beam can be transported at ten times the desired boron implantation energy, enabling very shallow implants without significant beam transmission losses. In addition, at a given beam current, each unit of current delivers ten times the dose to the workpiece. Finally, because the charge per unit dose is one-tenth that of a monatomic beam implant, workpiece charging problems are much less severe for a given dose rate.




Accordingly, a preferred embodiment of an improved ion source for an ion implanter has been described. With the foregoing description in mind, however, it is understood that this description is made only by way of example, that the invention is not limited to the particular embodiments described herein, and that various rearrangements, modifications, and substitutions may be implemented with respect to the foregoing description without departing from the scope of the invention as defined by the following claims and their equivalents.



Claims
  • 1. An ionizer (53) for an ion implanter, comprising:a body (96) having an inlet (119) for receiving a vaporized source material, said inlet provided with a heating mechanism (90) to heat the vaporized source material as it passes through said body; an ionization chamber (108) in which the heated vaporized source material may be ionized by an electron-emitting element (110) to create a plasma; an exit aperture (126) for extracting an ion beam comprised of said plasma; and a cooling mechanism (100, 104) for lowering the temperature of walls (128) of said ionization chamber (108) during the ionization of said heated vaporized source material.
  • 2. The ionizer (53) of claim 1, wherein said vaporized material is vaporized decaborane.
  • 3. The ionizer (53) of claim 2, wherein said body (96) is generally cylindrical in shape and constructed of aluminum.
  • 4. The ionizer (53) of claim 2, wherein said cooling mechanism comprises one or more passageways (100, 104) through which a cooling medium may be circulated.
  • 5. The ionizer (53) of claim 2, wherein said cooling mechanism maintains said walls (128) of said ionization chamber (108) below 350° C. to prevent dissociation of vaporized decaborane molecules.
  • 6. The ionizer (53) of claim 2, wherein said aperture (126) is sized to provide a focused ion beam current of between 100-500 microamps (μA) at a beam current density of <1 milliamp per square centimeter (mA/cm2).
  • 7. The ionizer (53) of claim 2, wherein said plasma has a density within said chamber (108) on the order of 1010/cm3.
  • 8. The ionizer (53) of claim 2, wherein said electron-emitting element (110) comprises a filament (114) that emits a first group of electrons that are accelerated toward an endcap (118) that in turn emits a second group of electrons which strike the vaporized decaborane in said ionization chamber (108) to create the plasma, and wherein said ionizer further comprises a repeller (112) for repelling a portion of said second group of electrons back toward said electron-emitting element.
  • 9. The ionizer (53) of claim 8, wherein said repeller (112) is water-cooled.
  • 10. The ionizer (53) of claim 8, wherein the arc discharge between the endcap (118) and the ionization chamber wall (128) is operated at a power level of approximately 5 watts (W) and at an electrical current level of about 50 milliamps (mA).
RELATED APPLICATION

The following U.S. patent application, commonly assigned to the assignee of the present invention, is incorporated by reference herein as if it had been fully set forth. Application Ser. No. 09/070,685, filed Apr. 30, 1998, and entitled DECABORANE VAPORIZER.

US Referenced Citations (1)
Number Name Date Kind
5661308 Benveniste et al. Aug 1997
Foreign Referenced Citations (1)
Number Date Country
10-163123 Jun 1998 JP
Non-Patent Literature Citations (8)
Entry
K. Goto, J. Matsuo*, T. Sugii, H. Minakata, I. Yamada*, and T. Hisatsugu (Novel Shallow Junction Technology using Decaborane (B10H14), * Ion Beam Engineering Experimental Lab., Kyoto University, Sakyo, Kyoto 606-01, Japan.
Daisuke Takeuchi, Norihiro Shimada, Jiro Matsuo and Isao Yamada Ion Beam Engineering Experimental Laboratory., Kyoto University, Sakyo, Kyoto 606-01, Japan (Shallow Junction Formation by Polyatomic Cluster Ion Implantation) Reprinted from IEEE Proceedings of the 11th Intl'l Conference on Ion Implantation Technology, Austin, TX, vol. 1, Issue 1, Jun. 16-21, 1996.
Jiro Matsuo, Daisuke Takeuchi, Takaaki Aoki and Isao Yamada Ion Beam Engineering Experimental Laboratory, Kyoto University, Sakyo, Kyoto 606-01, Japan (Cluster Ion Implantation for Shallow Junction Formation) Reprinted from IEEE Proceedings of the 11th Int'l Conference on Ion Implantation Technology, Austin, TX, vol. 1, Issue 1, Jun. 16-21, 1996.
Ken-ichi Goto, Jiro Matsuo*, Yoko Tada, Tetsu Tanaka, Youichi Momiyama, Toshihiro Sugii, and Isao Yamada* (A High Peformance 50 nm PMOSFET using Decaborane B10H14) Ion Implantation and 2-step Activation Annealing Process * Ion Beam Engineering Experimental Lab., Kyoto University, Sakyo, Kyoto 606-01, Japan.
Roger Smith and Marcus Shaw, Roger P. Webb, Majeed A. Foad (Ultrashallow junctions in Si using decaborane? A molecular dynamics simulation study) Received Sep. 4, 1997: accepted for publication Dec. 2, 1997).
Majeed A. Foad, Robert Webb, Roger Smith, Erin Jones, Amir Al-Bayati, Mark Lee, Vikas Agrawal, Sanjay Banerjee, Jiro Matsuo, and Isao Yamada (Formation of Shallow Junctions Using Decaborane Molecular Ion Implantation; Comparison With Molecular Dynamic Simulation).
Aditya Agarwal, H.-J. Gossmann, D. C. Jacobson, and D. J. Eaglesham, M. Sosnowski and J. M. Poate, I. Yamada and J. Matsuo, T. E. Haynes (Transient enhanced diffusion from decaborane molecular ion implantation) Received Feb. 4, 1998; accepted for publication Aug. 5, 1998.
Marek Sosnowski, Ravidath Gurudath, John Poate, Anthony Mujsce, Dale Jacobson (Decaborane As Ion Source Material For Boron Implantation).