Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
  • C23C16/455—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating characterised by the method used for introducing gases into reaction chamber or for modifying gas flows in reaction chamber
  • C23C16/45502—Flow conditions in reaction chamber
  • C23C16/45504—Laminar flow
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
  • C23C16/455—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating characterised by the method used for introducing gases into reaction chamber or for modifying gas flows in reaction chamber
  • C23C16/45587—Mechanical means for changing the gas flow
  • C23C16/45589—Movable means, e.g. fans
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
  • C23C16/458—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating characterised by the method used for supporting substrates in the reaction chamber
  • C23C16/4582—Rigid and flat substrates, e.g. plates or discs
  • C23C16/4583—Rigid and flat substrates, e.g. plates or discs the substrate being supported substantially horizontally
  • C23C16/4584—Rigid and flat substrates, e.g. plates or discs the substrate being supported substantially horizontally the substrate being rotated
• • C—CHEMISTRY; METALLURGY
  • C30—CRYSTAL GROWTH
  • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
  • C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
  • C30B25/02—Epitaxial-layer growth
  • C30B25/14—Feed and outlet means for the gases; Modifying the flow of the reactive gases
• • C—CHEMISTRY; METALLURGY
  • C30—CRYSTAL GROWTH
  • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
  • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
  • C30B29/10—Inorganic compounds or compositions
  • C30B29/40—AIIIBV compounds wherein A is B, Al, Ga, In or Tl and B is N, P, As, Sb or Bi
  • C30B29/403—AIII-nitrides
• • C—CHEMISTRY; METALLURGY
  • C30—CRYSTAL GROWTH
  • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
  • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
  • C30B29/10—Inorganic compounds or compositions
  • C30B29/40—AIIIBV compounds wherein A is B, Al, Ga, In or Tl and B is N, P, As, Sb or Bi
  • C30B29/403—AIII-nitrides
  • C30B29/406—Gallium nitride
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T117/00—Single-crystal, oriented-crystal, and epitaxy growth processes; non-coating apparatus therefor
  • Y10T117/10—Apparatus
  • Y10T117/1016—Apparatus with means for treating single-crystal [e.g., heat treating]

Definitions

• the present invention relates generally to chemical vapor deposition
• CVD chemical vapor deposition
• Metal organic chemical vapor deposition (MOCVD) of group lll-V compounds is a thin film deposition process utilizing a chemical reaction between a periodic table group III organic metal and a periodic table group V hydride.
• Various combinations of group III organic metal and group V hydride are possible.
• This process is commonly used in the fabrication of semiconductor devices, such as light emitting diodes (LEDs).
• the process usually takes place in a chemical vapor deposition (CVD) reactor.
• CVD reactor design is a critical factor in achieving the high quality films that are required for semiconductor fabrication.
• the gas flow dynamics for high quality film deposition favor laminar flow.
• Laminar flow as oppose to convective flow, is required to achieve high growth efficiency and uniformity.
• reactor designs are commercially available to provide laminar growth condition on a large scale, i.e., high throughput. These designs include the rotating disk reactor (RDR), the planetary rotating reactor (PRR) and the close-coupled showerhead (CCS).
• Such contemporary reactors suffer from inherent deficiencies which detract from their overall desirability, particularly with respect to high pressure and/or high temperature CVD processes. Such contemporary reactors generally work well at low pressures and relatively low temperatures (such as 30 torr and 700 °C, for example). Therefore, they are generally suitable for growing GaAs, InP based compounds. [0006] However, when growing group III nitride based compounds (such as GaN,
• group III Nitride is preferably grown at substantially higher pressures and temperatures (generally greater that 500 torr and greater than 1000 °C).
• pressures and temperatures generally greater that 500 torr and greater than 1000 °C.
• Ammonia is commonly used as nitrogen source in the III nitride MOCVD process. Ammonia is much more viscous than hydrogen. When the ambient gas contains a high percentage of ammonia, thermal convection occurs more easily than when the ambient gas is majority hydrogen, which is the case for GaAs or InP based MOCVD growth. Thermal convection is detrimental to growing high quality thin films since hard-to-control complex chemical reactions occur due to the extended duration of the presence of reactant gases in the growth chamber. This inherently results in a decrease in growth efficiency and poor film uniformity.
• An efficient reactor design for Ill-nitride growth does not avoid gas phase reaction, but rather controls the reaction so that it does not create such undesirable situations.
• thermal convection is as severe (or even more sever) in a larger reactor as in a smaller reactor, film uniformity, as well as wafer-to-wafer uniformity, are not any better (and may be much worse).
• a very high gas flow rate is needed to suppress thermal convection. The amount of gas flow needed is so high that modification and special considerations are required for the gas delivery system.
• the larger mechanical parts of such a scaled up (larger) reactor are inherently placed under higher thermal stress and consequently tend to break prematurely. In almost all reactor constructions, stainless steel, graphite and quartz are the most commonly used materials.
• the reaction chamber has a double-walled water-cdoled 10" cylinder 11 , a flow flange 12 where all the reaction or source gases are distributed and delivered into chamber 13, a rotation assembly 14 that spins the wafer carrier 16 at several hundreds of rotations per minute, a heater 17 assembly underneath the spinning wafer carrier 16 configured to heat wafers 10 to desired process temperatures, a pass through 18 to facilitate wafer carrier transfer in and out of the chamber 13, and an exhaust 19 at the center of the bottom side of the chamber 13.
• An externally driven spindle 21 effects rotation of the wafer carrier 16.
• the wafer carrier 16 comprises a plurality of pockets, each of which is configured to contain a wafer 10.
• the heater 17 comprises two sets of heating elements. An inner set of heating elements 41 heats the central portion of the wafer carrier 16 and an outer set of heating elements 42 heats the periphery of the wafer carrier 16. Because the heater 17 is inside of the chamber 13, it is exposed to the detrimental effects of the reaction gases.
• the spindle rotates the wafer carrier at between 500 and 1000 rpm.
• FIG 2 a simplified gas streamline is shown to illustrate this turbulence. It is clear that turbulence increase as the size of the chamber and/or the distance between the wafer carrier and the top of the chamber increases.
• the chamber 13, as well as the wafer carrier 16, is enlarged to support and contain more wafers.
• Gas recirculation cells 50 tend to form when there is turbulence in the ambient gas. As those skilled in the art will appreciate, such recirculation is undesirable because it results in undesirable variations in reactant concentration and temperature. Further, such recirculation generally results in reduced growth efficiency due to ineffective use of the reactant gas.
• a reactor which is not substantially susceptible to the undesirable effects of thermal convection and which can easily and economically be scaled up so as to increase throughput. It is further desirable to provide a reactor which has enhanced growth efficiency (such as by providing mixing of reactant gases immediately proximate a growth region of the wafers and by assuring intimate contact of the reactant gases with the growth region). It is yet further desirable to provide a reactor wherein the heater is outside of the chamber thereof, and is thus not exposed to the detrimental effects of the reaction gases.
• the present invention specifically addresses and alleviates the above mentioned deficiencies associated with the prior art. More particularly, according to one aspect, the present invention comprises a chemical vapor deposition reactor comprising a rotatable wafer carrier which cooperates with a chamber of the reactor to facilitate laminar flow of reaction gas within the chamber.
• the present invention comprises a chemical vapor deposition reactor comprising a rotatable wafer carrier which is sealed at a periphery thereof to a chamber of the reactor such that laminar flow within the chamber is facilitated.
• the present invention comprises a chemical vapor deposition reactor comprising a chamber and a rotatable wafer carrier disposed within the chamber, the wafer carrier being configured so as to enhance outward flow of reaction gas within the chamber.
• the present invention comprises a chemical vapor deposition reactor comprising a rotatable wafer carrier and a reaction chamber, a bottom of the reaction chamber being substantially defined by the wafer carrier.
• the present invention comprises a chemical vapor deposition reactor comprising a chamber, a wafer carrier disposed within the chamber, and a heater disposed outside of the chamber, the heater being configured to heat the wafer carrier.
• the present invention comprises a chemical vapor deposition reactor comprising a plurality of chambers and at least one of a common reactant gas supply system and a common gas exhaust system.
• the present invention comprises a chemical vapor deposition reactor comprising a wafer carrier configured such that reactant gas does not flow substantially below the wafer carrier.
• the present invention comprises a chemical vapor deposition reactor comprising a chamber, a wafer carrier, a gas inlet located generally centrally within the chamber, and at least one gas outlet formed in the chamber entirely above an upper surface of the wafer carrier so as to enhance laminar gas flow through the chamber.
• Figure 1 is a semi-schematic cross-sectional side view of a contemporary reactor showing reaction gas being introduced thereinto in a dispersed fashion via a flow flange and showing the gas being exhausted from the chamber via a gas outlet disposed below the wafer carrier;
• Figure 2 is a semi-schematic cross-sectional side view of a contemporary reactor showing undesirable convection caused re-circulation of reaction gas within the chamber, wherein the re-circulation is facilitated by the comparatively large distance between the top of the chamber and the wafer carrier;
• Figure 3A is a semi-schematic top view of a wafer carrier which is configured so as to support six wafers within a reactor;
• Figure 3B is a semi-schematic top view of a wafer carrier which is configured so as to support twenty wafers within a reactor;
• Figure 4 is a semi-schematic cross-sectional side view of a reactor having a comparatively small distance between the top of the chamber and the wafer carrier and having a single comparatively small gas inlet disposed generally centrally with respect to the wafer carrier according to the present invention
• Figure 5 is a semi-schematic cross-sectional side view of an alternative configuration of the reactor of Figure 4, having a plurality of reaction gas outlets disposed entirely above the upper surface of the wafer carrier and in fluid communication with a ring diffuser so as to enhance laminar gas flow, having a seal disposed between the wafer carrier and the chamber, and having a heater disposed outside of the chamber along with a heater gas purge so as to mitigate the effects of reactant gas upon the heater, according to the present invention;
• Figure 6A is a semi-schematic cross-sectional top view of the reactor of
• FIG. 5 showing a three pocket wafer carrier, the seal between the wafer carrier and the chamber, the diffuser, and the reaction gas outlets;
• Figure 6B is a semi-schematic perspective side view of the diffuser of
• Figures 5 and 6A showing a plurality of apertures formed in the inner surface and the outer surface thereof;
• Figure 7 is a semi-schematic cross-sectional side view of an alternative configuration of the reactor of Figure 5, having a separate alkyl inlet and a separate ammonia inlet providing reaction gas to a carrier gas;
• Figure 8 is a semi-schematic cross-sectional side view of an alternative configuration of the reactor of Figure 5, having an ammonia inlet disposed generally concentrically within an alkyl/carrier gas inlet;
• Figure 9 is a semi-schematic perspective side view of a comparative large, scaled up RDR reactor having a twenty-one wafer capacity and having a plurality of reaction gas inlets;
• Figure 10 is a semi-schematic perspective side view of a reactor system having three comparatively small reactors (each of which has a seven wafer capacity such that the total capacity is equal to that of the comparative large reactor of Figure 9) which share a common reaction gas supply system and a common reaction gas exhaust system.
• the present invention comprises a chemical vapor deposition reactor comprising a rotatable wafer carrier which cooperates with a chamber of the reactor to facilitate laminar flow of reaction gas within the chamber.
• the present invention comprises a chemical vapor deposition reactor comprising a rotatable wafer carrier which is sealed at a periphery thereof to a chamber of the reactor such that laminar flow within the chamber is facilitated.
• the present invention comprises a chemical vapor deposition reactor comprising a chamber and a rotatable wafer carrier disposed within the chamber, the wafer carrier being configured so as to enhance outward flow of reaction gas within the chamber.
• the present invention comprises a chemical vapor deposition reactor comprising a rotatable wafer carrier and a reaction chamber, a bottom of the reaction chamber being substantially defined by the wafer carrier.
• the present invention comprises a chemical vapor deposition reactor comprising a chamber, a wafer carrier disposed within the chamber, and a heater disposed outside of the chamber, the heater being configured to heat the wafer carrier.
• the present invention comprises a chemical vapor deposition reactor comprising a plurality of chambers and at least one of a common reactant gas supply system and a common gas exhaust system.
• the present invention comprises a chemical vapor deposition reactor comprising a wafer carrier configured such that reactant gas does not flow substantially below the wafer carrier.
• the present invention comprises a chemical vapor deposition reactor comprising a chamber, a wafer carrier, a gas inlet located generally centrally within the chamber, and at least one gas outlet formed in the chamber entirely above an upper surface of the wafer carrier so as to enhance laminar gas flow through the chamber.
• the present invention comprises a chemical vapor deposition reactor comprising a chamber, a wafer carrier disposed within the chamber and cooperating with a portion (for example, the top) of the chamber to define a flow channel, and a shaft for rotating the wafer carrier.
• a distance between the wafer carrier and the portion of the chamber is small enough to effect generally laminar flow of gas through the flow channel.
• the distance between the wafer carrier and the portion of the chamber is small enough for centrifugal force caused by rotation of the wafer carrier to effect outward movement of gas within the channel.
• the distance between the wafer carrier and the portion of the chamber is small enough that a substantial portion of the reactants in the reaction gas contact a surface of a wafer prior to exiting the chamber.
• the distance between the wafer carrier and the portion of the chamber is small enough that most of the reactants in the reaction gas contact a surface of a wafer prior to exiting the chamber.
• the distance between the wafer carrier and the portion of the chamber is small enough to mitigate thermal convection intermediate the chamber and the wafer carrier.
• the distance between the wafer carrier and the portion of the chamber is less than approximately 2 inches.
• the distance between the wafer carrier and the portion of the chamber is between approximately 0.5 inch and approximately 1.5 inches.
• the distance between the wafer carrier and the portion of the chamber is approximately 0.75 inch.
• a gas inlet formed above the wafer carrier and generally centrally with respect thereto.
• the chamber is defined by a cylinder.
• the chamber is defined by a cylinder having one generally flat wall thereof defining a top of the chamber and the reaction gas inlet in located at approximately a center of the top of the chamber.
• the chamber may alternatively be defined by any other desired geometric shape.
• the chamber may alternatively be defined by a cube, a box, a sphere, or an ellipsoid.
• the chemical vapor the wafer carrier is configured to rotate about an axis thereof and the reaction gas inlet is disposed generally coaxially with respect to the axis of the wafer carrier.
• the reaction gas inlet has a diameter which is less that 1/5 of a diameter of the chamber.
• the reaction gas inlet has a diameter which is less than approximately 2 inches.
• the reaction gas inlet has a diameter which is between approximately .25 inch and approximately 1.5 inch.
• the reaction gas inlet is sized so as to cause reaction gas to flow generally from a center of the wafer carrier to a periphery thereof in a manner that results in substantially laminar reaction gas flow. In this manner convection currents are mitigated and reaction efficiency is enhanced.
• the reaction gas is constrained to flow generally horizontally within the chamber.
• the reaction gas is constrained to flow generally horizontally through the channel.
• the reaction gas is caused to flow outwardly at least partially by a rotating wafer carrier.
• the at least one reaction gas outlet formed in the chamber above a wafer carrier Preferably, a plurality of reaction gas outlets is formed in the chamber entirely above the upper surface of the wafer carrier. Increasing the number of reaction gas outlet(s) enhances laminar flow of the reaction gas, particularly at the periphery of the wafer carrier, by facilitating radial flow of the reaction gas (by providing more straight line paths for gas flow from the center of the wafer carrier to the periphery thereof). Forming the reaction gas outlets entirely above the upper surface of the wafer carrier mitigates undesirable turbulence in the reaction gas flow resulting from the reaction gas flowing over an edge of the wafer carrier.
• At least one reaction gas outlet is preferably formed in the chamber above a wafer carrier and below a top of the chamber.
• the chemical vapor deposition reactor preferably comprises a reaction gas inlet formed generally centrally within the chamber and at least one reaction gas outlet formed in the chamber.
• the wafer carrier is disposed within the chamber below the gas outlet(s) so as to define a flow channel intermediate a top of the chamber and the wafer carrier such that reaction gas flows into the chamber through the reaction gas inlet, through the chamber via the flow channel, and out of the chamber via the reaction gas outlet.
• a ring diffuser is preferably disposed proximate a periphery of the wafer carrier and configured so as to enhance laminar flow from the reaction gas inlet to the reaction gas outlet.
• the wafer carrier is disposed within the chamber below the gas outlets so as to define a flow channel intermediate a top of the chamber and the wafer carrier such that reaction gas flows into the chamber through the reaction gas inlet, through the chamber via the flow channel, and out of the chamber via the reaction gas outlet.
• the ring diffuser preferably comprises a substantially hollow annulus having an inner surface and an outer surface, a plurality of openings formed in the inner surface, and a plurality of openings form in the outer surface.
• the openings in the inner surface enhance uniformity of reaction gas flow over the wafer carrier.
• the openings in the inner surface are preferably configured so as to create enough restriction to reaction gas flow therethrough so as to enhance a uniformity of reaction gas flow over the wafer carrier.
• the ring diffuser is preferably comprised of a material which is resistant to deterioration caused by heated ammonia.
• the ring diffuser may be formed of SiC coated graphite, SiC, quartz, or molybdenum.
• a ring seal is disposed intermediate the wafer carrier and the chamber.
• the ring seal is configured to mitigate reaction gas flow out of the chamber other than from the reaction gas outlet.
• the ring seal preferably comprises either graphite, quartz, or SiC.
• a heater assembly is disposed outside of the chamber and proximate the wafer carrier.
• the heater may be an induction heater, a radiant heater, or any other desired type of heater.
• a heater purge system is configured to mitigate contact of reaction gas with the heater.
• a gas flow controller is configured to control the amount of reactant gases introduced into the chamber via the gas inlet port.
• the wafer carrier is preferably configured to support at least three 2 inch round wafers.
• the wafer carrier may alternatively be configured so as to support any desired number of wafers, any desired size of wafers, and any desired shape of wafers.
• the wafer carrier is configured so as to facilitate outward flow of reaction gas due to centrifugal force.
• the wafer carrier preferably comprises a rotating wafer carrier.
• the wafer carrier is preferably configured to rotate at greater than approximately 500 rpm.
• the wafer carrier is configured to rotate at between approximately 100 rpm and approximately 1500 rpm.
• the wafer carrier is preferably configured to rotate at approximately 800 rpm.
• the apparatus and method of the present invention may be used to form wafers, from which a variety of different semiconductor devices may be formed.
• the wafers may be used to form die from which LEDs are fabricated.
• the present invention is illustrated in Figures 1 - 10, which depict presently preferred embodiments thereof.
• the present invention relates to a chemical vapor deposition (CVD) reactor and an integrated multi-reactor system which is suitable for scaled up throughput.
• the reactor employs a geometry that substantially suppresses thermal convection, a gas injection scheme providing very high gas velocity to avoid adduct adhesion to surface, and a restricted growth zone to enhance growth efficiency (by reducing source gas consumption).
• each reactor in the multiple-unit configuration can be of a relatively small scale in size, so that the mechanical construction can be simple and reliable. All reactors share common gas delivery, exhaust and control systems so that cost is similar to the larger conventional reactor with the same throughput.
• the throughput scaling up concept is independent with respect to reactor design and can also be applied to various other reactor designs. In theory, there is no limit in how many reactors can be integrated in one system. But as a practical matter, the maximum number of reactors integrated is substantially limited by how the gas delivery system is configured. Both reactor design and the scaling up concept can also be applied to the growth of various different materials, and thus includes but is not limited to group Ill-nitride, all other group lll-V compounds, oxides, nitrides, and group V epitaxy.
• a reactor 100 has a narrow gas inlet 112 located at the top and center of the reactor cylinder 111.
• the cylinder 111 is double walled and water cooled, like the reactor shown in Figure 1.
• the temperature of the water can be varied so as to control the temperature of the chamber 113.
• a narrow gas channel 130 defined by the wafer carrier 116 and the top 131 of the reactor 100 directs gas outwardly.
• Pockets formed in the wafer carrier 116 are configured to receive and support wafers 110, such as 2 inch wafers suitable for use in the fabrication of LEDs.
• the rotating wafer carrier 116 assists gas flow outwardly by its centrifugal force.
• the rotating wafer carrier 116 preferably rotates at between 10 and 1500 rpm. As those skilled in the art will appreciate, higher rotational speeds of the wafer carrier 116 typically result in greater centrifugal force being applied to the reaction gas.
• the gas By introducing the gas from the center, the gas is forced to flow generally horizontally in the narrow channel 130, making the growth process somewhat simulate a horizontal reactor.
• a horizontal reactor one advantage of a horizontal reactor is its higher growth efficiency. This is because all the reactants in a horizontal reactor are restricted to a much narrower volume, thus making the reactants more efficient in their contact with the growing surface.
• the reaction gas inlet has a diameter, dimension A, which is less that 1/5 of a diameter of the chamber.
• the reaction gas inlet has a diameter which is less than approximately 2 inches.
• the reaction gas inlet has a diameter which is between approximately .25 inch and approximately 1.5 inch.
• dimension B The distance between the upper surface of the wafer carrier 116 and the top of the chamber 111 is designated as dimension B.
• Dimension B is preferably less than approximately 2 inch.
• Dimension B is preferably between approximately 0.5 inch and approximately 1.5 inch.
• Dimension B is preferably approximately 0.75 inch.
• growth efficiency is improved by using a comparatively high wafer carrier rotation rate, so that the centrifugal force generated by the rotation of the wafer carrier enhances the gas speed over the wafers without using higher gas flow rate.
• gas flow resistance can be reduced, so that a higher degree of laminar flow is produced, by forming the reaction gas outlet(s) such that they are entirely above the upper surface of the wafer carrier.
• the reaction gas outlet entirely above the upper surface of the wafer carrier 116, a more direct route (and thus less contorted) for the reaction gas from the gas inlet 112 to the gas outlet 119 is provided.
• the more direct and the less contorted the route of the reaction gas the less turbulent (and more laminar) its flow will be.
• ring seal 132 By adding a ring seal 132 around the rotating wafer carrier 116 to bridge the flow channel 130 of the exhaust gas flow, flow resistance is reduced and laminar flow substantially enhanced. This is because a change of gas flow direction at the wafer carrier's edge is eliminated.
• the ring seal 132 can be made of quartz, graphite, SiC or other durable materials for suitable for the reactor's environment.
• a ring shaped diffuser 133 (better shown in Figures 6A and 6B) can be used.
• the ring shaped diffuser 133 effectively makes almost the entire periphery of the reactor, proximate the periphery of the wafer carrier 132, one generally continuous gas outlet port.
• a heater 117 is disposed outside of the chamber (which is that portion of the reactor within which reaction gas readily flows).
• the heater is disposed beneath the wafer carrier 116. Since the ring seal 132 mitigates reaction gas flow beneath the wafer carrier 116, the heater is not substantially exposed to reaction gas and thus is not substantially degraded thereby.
• a heater purge 146 is provided so as to purge any reaction gas that leaks past the ring seal 132 into the area beneath the wafer carrier.
• FIG. 6A four pumping ports or gas outlets 119 are in fluid communication with the diffuser 133. All of the gas outlets 119 are preferably connected to a common pump. [00104]
• the ring seal 132 bridges the gap between the wafer carrier 116 and the chamber 111 , so as to facilitate laminar flow of reaction gas, as discussed above.
• the diffuser 133 comprises a plurality of inner apertures 136 and a plurality of outer apertures 137.
• the more nearly the inner apertures approximate a single continuous opening the more laminar the gas flow through the chamber.
• the diffuser 133 preferably comprises at least as many outer apertures as there are gas outlet ports (there are, for example, four gas outlet ports 119 shown in Figure 5A).
• the diffuser 133 is preferably made of graphite, SiC coated graphite, solid
• SiC silicon carbide
• quartz quartz
• molybdenum or other material that resist hot ammonia.
• various materials are suitable.
• the size of the holes in the diffuser 133 can be made small enough to create slight restriction to the gas flow so that more even distribution to the exhaust can be achieve. However, the hole size should not be made so small that clogging is likely to occur, since reaction product contains vapor and solid particulate that may adhere to or condense upon the diffuser holes.
• the reactant gas injection configuration can be modified to improve gas phase reaction.
• alkyls and ammonia are mostly separated before being introduced into the reaction chamber as shown in Figure 7, and are completely separated before entering the reaction chamber as shown in Figure 8.
• the reactants are mixed immediately before reaching the growth zone where wafers are located.
• Gas phase reaction only happens in a very short time before gases participate in the growth process.
• an alkyl inlet 141 is separate from an ammonia inlet 142. Both the alkyl inlet 141 and the ammonia inlet 142 provide a reaction gas to the carrier gas inlet 112 immediately prior to these gases entering the chamber 111.
• the alkyl inlet 141 provides a reaction gas to the carrier inlet 112 much the same as in Figure 7.
• the ammonia inlet 151 comprises a tube disposed within the carrier inlet 112.
• the ammonia inlet is preferably disposed generally concentrically within the carrier inlet 112.
• those skilled in the art will appreciate that various other configurations of the alkyl inlet 141 , the ammonia inlet 151 , and the carrier inlet 112 are likewise suitable.
• a nozzle 161 tends to spread ammonia evenly across the wafer carrier 116 so as to provide enhance reaction efficiency.
• an advantage of the reactor configuration shown in Figures 5, 7, and 8 is the significant reduction of undesirable deposits upon the heater 117.
• the heater assembly can be either a radiant heater or a radio frequency (RF) inductive heater.
• RF radio frequency
• the present invention comprises a way to scale up the throughput of a metal organic chemical vapor deposition (MOCVD) system or the like. Unlike contemporary attempts to scale up a MOCVD reactor by increasing the size of the reaction chamber, present invention integrates several smaller reactor modules to achieve the same wafer throughput.
• MOCVD metal organic chemical vapor deposition
• gas is usually introduced through multiple ports 901-903 so as to provide even distribution thereof.
• Gas flow controllers 902 facilitate control of the amount of reaction gas and the amounts of the components of the reaction gas provided to the chambers.
• a gas supply system 940 provides reaction gas to the ports 901-903.
• a gas exhaust system 950 removes the spent reaction gas from the reactor 111.
• Each chamber 951-953 is a comparatively small chamber, each defining, for example, a seven wafer reactor. All of the reactors share the same gas inlet system 960 and gas exhaust system 970.

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• 2003
  • 2003-07-15 US US10/621,049 patent/US20050011459A1/en not_active Abandoned
  • 2003-12-03 US US10/727,746 patent/US20050011436A1/en not_active Abandoned
• 2004
  • 2004-06-29 KR KR1020067001007A patent/KR100816969B1/ko not_active Expired - Fee Related
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  • 2004-06-29 WO PCT/US2004/021001 patent/WO2005010227A2/en not_active Ceased
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