[go: up one dir, main page]
More Web Proxy on the site http://driver.im/

US20200157704A1 - Method for carrying out phosphide in-situ injection synthesis by carrier gas - Google Patents

Method for carrying out phosphide in-situ injection synthesis by carrier gas Download PDF

Info

Publication number
US20200157704A1
US20200157704A1 US16/475,831 US201716475831A US2020157704A1 US 20200157704 A1 US20200157704 A1 US 20200157704A1 US 201716475831 A US201716475831 A US 201716475831A US 2020157704 A1 US2020157704 A1 US 2020157704A1
Authority
US
United States
Prior art keywords
carrier gas
phosphorus
furnace
conduit
furnace body
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
US16/475,831
Other versions
US10648100B1 (en
Inventor
Niefeng SUN
Shujie WANG
Huisheng Liu
Tongnian SUN
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
CETC 13 Research Institute
Original Assignee
CETC 13 Research Institute
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by CETC 13 Research Institute filed Critical CETC 13 Research Institute
Application granted granted Critical
Publication of US10648100B1 publication Critical patent/US10648100B1/en
Publication of US20200157704A1 publication Critical patent/US20200157704A1/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • 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
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/08—Other phosphides
    • 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
    • C30B28/00—Production of homogeneous polycrystalline material with defined structure
    • C30B28/12—Production of homogeneous polycrystalline material with defined structure directly from the gas state
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
    • B01F23/10—Mixing gases with gases
    • B01F23/19—Mixing systems, i.e. flow charts or diagrams; Arrangements, e.g. comprising controlling means
    • B01F23/191—Mixing systems, i.e. flow charts or diagrams; Arrangements, e.g. comprising controlling means characterised by the construction of the controlling means
    • B01F3/028—
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/08—Other phosphides
    • C01B25/082—Other phosphides of boron, aluminium, gallium or indium
    • C01B25/087—Other phosphides of boron, aluminium, gallium or indium of gallium or indium
    • 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
    • C30B11/00—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method
    • C30B11/04—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method adding crystallising materials or reactants forming it in situ to the melt
    • C30B11/06—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method adding crystallising materials or reactants forming it in situ to the melt at least one but not all components of the crystal composition being added
    • 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
    • C30B29/44—Gallium phosphide
    • 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
    • C30B35/00—Apparatus not otherwise provided for, specially adapted for the growth, production or after-treatment of single crystals or of a homogeneous polycrystalline material with defined structure
    • C30B35/002—Crucibles or containers
    • 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
    • C30B35/00—Apparatus not otherwise provided for, specially adapted for the growth, production or after-treatment of single crystals or of a homogeneous polycrystalline material with defined structure
    • C30B35/005—Transport systems
    • 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
    • C30B35/00—Apparatus not otherwise provided for, specially adapted for the growth, production or after-treatment of single crystals or of a homogeneous polycrystalline material with defined structure
    • C30B35/007—Apparatus for preparing, pre-treating the source material to be used for crystal growth

Definitions

  • the invention relates to a synthesis method of semiconductor crystal, in particular to a synthesis method of compound crystal material with volatile elements, such as indium phosphide, gallium phosphide and the like.
  • the compounds containing elements such as phosphorus or sulfur are widely used in the electronic industry, and they are important compound semiconductor materials such as indium phosphide and gallium phosphide. Because of the unique physical characteristics, these materials are widely used in many high-tech fields such as terahertz, optical communication, microwave, millimeter wave devices, radiation-resistant solar cells, etc. Therefore, compound semiconductor materials containing elements such as phosphorus or sulfur have been paid more and more attention.
  • the problem to be solved by the invention is to provide a method for carrying out phosphide in-situ injection synthesis by carrier gas, wherein a shielding inert gas is used as carrier gas, and phosphorus gas in a phosphorus source furnace is injected into the melt in a crucible to synthesize phosphide, so that the melt is prevented from being sucked back into the phosphorus source furnace after the volatile element gas is completely absorbed.
  • a method for carrying out phosphide in-situ injection synthesis by carrier gas which is characterized by including the following steps of:
  • step A introducing shielding inert gas into a furnace body through a carrier gas intake conduit, and the shielding inert gas is stopped being introduced when the pressure in the furnace body reaching a preset pressure is detected;
  • step B heating the crucible in the furnace body to melt the pre-synthesized raw material in the crucible until the temperature required for phosphide synthesis is reached;
  • step C introducing the carrier gas into the furnace body through a carrier gas intake conduit, and meanwhile opening and adjusting a carrier gas exhaust conduit so that the injection amount of the carrier gas is equal to the outflow amount of the gas;
  • step D moving the phosphorus source furnace loaded with red phosphorus downwards until the injection conduit on the phosphorus source furnace is submerged in the melt and lowered close to the bottom of the crucible;
  • step E heating the red phosphorus by the phosphorus source furnace to produce phosphorus gas, and mixing the phosphorus gas with the carrier gas and then injecting it into the melt through the injection conduit, and the phosphorus gas reacts with the melt to synthesize phosphide;
  • step F after the synthesis is finished, slowly lifting and turning off the phosphorus source furnace, and then stopping introducing the carrier gas into the furnace body, and finally stopping heating the crucible.
  • the carrier gas shielding inert gas such as nitrogen or argon
  • the carrier gas intake conduit such that the carrier gas enables phosphorus gas to be stably injected into the melt to prevent the melt from being sucked back into the phosphorus source furnace after volatile element gas is completely absorbed
  • a phosphorus gas absorber is added so that the phosphorus gas can be prevented from polluting the environment
  • the whole process is stable, and the synthesis efficiency is high, and the explosion phenomenon of the volatile gas carrier is unlikely to occur.
  • FIG. 1 is a schematic view showing an internal structure of a furnace body in a method for carrying out phosphide in-situ injection synthesis by carrier gas according to the present invention.
  • FIG. 2 is a schematic structural view of a phosphorus source furnace and a gas heating device of FIG. 1 .
  • 1 is a furnace body
  • 2 is a crucible
  • 3 is a crucible heating device
  • 4 is a phosphorus source furnace
  • 4 - 1 is a solid phosphorus loader
  • 4 - 2 is a thermal insulating sleeve
  • 4 - 3 is a heating wire
  • 4 - 4 is an injection conduit
  • 5 is a carrier gas intake conduit
  • 6 is a carrier gas exhaust conduit
  • 7 is a first pressure reducing valve
  • 8 is a first flow meter
  • 9 is a second pressure reducing valve
  • 10 is a second flow meter
  • 11 is a pressure gauge
  • 12 is a phosphorus absorber
  • 13 is a carrier gas heating device
  • 13 - 1 is a carrier gas heating conduit
  • 13 - 2 is a carrier gas heating and thermal insulating cavity
  • 13 - 3 is a carrier gas heating wire
  • 13 - 4 is a carrier gas injection conduit
  • 13 - 5 is a carrier gas heating multi-tube
  • the invention provides a method for carrying out phosphide in-situ injection synthesis by carrier gas, wherein the carrier gas is used for stably injecting phosphorus gas into melt so as to synthesize phosphide, and the melt can be prevented from being sucked back into a phosphorus source furnace.
  • Step A shielding inert gas was introduced into a furnace body 1 through a carrier gas intake conduit 5 , and the shielding inert gas was stopped being introduced when the pressure in the furnace body 1 reaching a preset pressure was detected.
  • the preset pressure set in the step was greater than the dissociation pressure required to synthesize the compound melt.
  • the carrier gas intake conduit 5 was communicated with a phosphorus source furnace 4 , and the shielding inert gas (nitrogen or argon) and the carrier gas (nitrogen or argon) both entered the furnace body 1 through the phosphorus source furnace 4 .
  • Step B a crucible 2 in the furnace body 1 was heated to melt the pre-synthesized raw material in the crucible 2 until the temperature required for phosphide synthesis was reached.
  • Step C the carrier gas was introduced into the furnace body 1 through the carrier gas intake conduit 5 , and meanwhile a carrier gas exhaust conduit 6 was opened and adjusted so that the injection amount of the carrier gas was equal to the outflow amount of the gas.
  • the temperature of the carrier gas introduced was 850° C. ⁇ 900° C.
  • a first pressure reducing valve 7 and a first flow meter 8 were arranged on the carrier gas intake conduit 5 , and the first pressure reducing valve 7 and the first flow meter 8 were located outside the furnace body 1 .
  • a second pressure reducing valve 9 and a second flow meter 10 were arranged on the carrier gas exhaust conduit 6 , and the second pressure reducing valve 9 and the second flow meter 10 were located outside the furnace body 1 .
  • the gas discharged from the carrier gas exhaust conduit 6 was introduced into a phosphorus absorber 12 loaded with high-purity cooling water to absorb unreacted phosphorus gas of step E, so that the environment was prevented from being polluted, and the discharged phosphorus which cooled into a solid could be recycled.
  • Step D the phosphorus source furnace 4 loaded with red phosphorus was moved down until an injection conduit 4 - 4 of the phosphorus source furnace 4 was submerged in the melt and it was lowered close to the bottom of the crucible 2 .
  • Step E the red phosphorus was heated by the phosphorus source furnace 4 to produce phosphorus gas; the phosphorus gas was mixed with the carrier gas, and then injected into the melt through the injection conduit 4 - 4 ; and the phosphorus gas reacted with the melt to synthesize phosphide.
  • step F after the synthesis was finished, the phosphorus source furnace 4 was slowly lifted and turned off, and then the carrier gas was stopped being introduced into the furnace body 1 , and finally the crucible 2 was stopped being heated.
  • Step A shielding inert gas was introduced into a furnace body 1 through a carrier gas intake conduit 5 , and the shielding inert gas was stopped being introduced when the pressure in the furnace body 1 reaching a preset pressure was detected.
  • the preset pressure set in the step was greater than the dissociation pressure required to synthesize the compound melt.
  • the carrier gas intake conduit 5 was communicated with a carrier gas heating device 13 , which was communicated with a phosphorus source furnace 4 , and the shielding inert gas and the carrier gas entered the furnace body 1 through the carrier gas intake conduit 5 , the carrier gas heating device 13 and the phosphorus source furnace 4 .
  • Step B a crucible 2 in the furnace body 1 was heated to melt the pre-synthesized raw material in the crucible 2 until the temperature required for phosphide synthesis was reached.
  • Step C the carrier gas was introduced into the furnace body 1 through the carrier gas intake conduit 5 , and meanwhile a carrier gas exhaust conduit 6 was opened and adjusted so that the injection amount of the carrier gas was equal to the outflow amount of the gas.
  • the carrier gas was heated by the carrier gas heating device 13 so that the temperature of the heated carrier gas was 850° C. ⁇ 900° C.
  • a first pressure reducing valve 7 and a first flow meter 8 were arranged on the carrier gas intake conduit 5 , and the first pressure reducing valve 7 and the first flow meter 8 were located outside the furnace body 1 .
  • a second pressure reducing valve 9 and a second flow meter 10 were arranged on the carrier gas exhaust conduit 6 , and the second pressure reducing valve 9 and the second flow meter 10 were located outside the furnace body 1 .
  • the gas discharged from the carrier gas exhaust conduit 6 was introduced into a phosphorus absorber 12 loaded with high-purity cooling water to absorb unreacted phosphorus gas of step E, so that the environment was prevented from being polluted, and the discharged phosphorus which cooled into a solid could be recycled.
  • Step D the phosphorus source furnace 4 loaded with red phosphorus and the carrier gas heating device 13 were moved down until an injection conduit 4 - 4 of the phosphorus source furnace 4 was submerged in the melt and they were lowered close to the bottom of the crucible 2 .
  • Step E the red phosphorus was heated by the phosphorus source furnace 4 to produce phosphorus gas; the phosphorus gas was mixed with the carrier gas, and then injected into the melt through the injection conduit 4 - 4 ; and the phosphorus gas reacted with the melt to synthesize phosphide.
  • the carrier gas and the unreacted phosphorus gas overflowed the melt into a furnace cavity of the furnace body 1 .
  • step F after the synthesis was finished, the phosphorus source furnace 4 was slowly lifted and turned off, and then the carrier gas was stopped being introduced into the furnace body 1 , and finally the crucible 2 was stopped being heated.
  • the shielding inert gas and the carrier gas are argon or nitrogen.
  • a crucible 2 is arranged at the bottom of a furnace cavity of a furnace body 1 ; a crucible heating device 3 is arranged outside the crucible 2 ; a heat preserving device 15 is arranged between the furnace body 1 and the crucible heating device 3 ; a phosphorus source furnace 4 is arranged above the crucible 2 ; a carrier gas intake conduit 5 and a carrier gas exhaust conduit 6 are arranged on the furnace body 1 ; the carrier gas intake conduit 5 is communicated with the phosphorus source furnace 4 through the furnace body 1 ; and the carrier gas exhaust conduit 6 is communicated with the furnace cavity of the furnace body 1 .
  • a pressure gauge 11 is provided on the furnace body 1 for easy observation of the pressure in the furnace.
  • a viewing window 14 is provided on the furnace body 1 for easy viewing of the synthesis process.
  • the structure of the phosphorus source furnace 4 includes a solid phosphorus loader 4 - 1 , a thermal insulating sleeve 4 - 2 positioned outside the solid phosphorus loader 4 - 1 , a heating wire 4 - 3 arranged in the thermal insulating sleeve 4 - 2 , and an injection conduit 4 - 4 for communicating the solid phosphorus loader 4 - 1 with the melt in the crucible 2 .
  • the carrier gas intake conduit 5 is provided with a gas heating device 13 , which is positioned in the furnace cavity of the furnace body 1 .
  • the structure of the gas heating device 13 includes a carrier gas heating conduit 13 - 1 with a carrier gas heating heat preserving cavity 13 - 1 , a carrier gas heating wire 13 - 3 arranged on the carrier gas heating conduit 13 - 1 , and a carrier gas injection conduit 13 - 4 for communicating the carrier gas heating conduit 13 - 1 with the phosphorus source furnace 4 .
  • a carrier gas heating multi-tube conduit 13 - 5 is arranged in the carrier gas heating conduit 13 - 1 .
  • the phosphorus source furnace 4 and the carrier gas heating device 13 are arranged in a connecting sleeve 16 , and an insulating layer 17 is further arranged between the phosphorus source furnace 4 and the carrier gas heating device 13 .
  • the connecting sleeve 16 With the arrangement of the connecting sleeve 16 , the phosphorus source furnace 4 is integrated with the carrier gas heating device 13 , and the carrier gas intake conduit 5 is connected to the connecting sleeve 16 .
  • the phosphorus source furnace 4 and the carrier gas heating device 13 are driven to move up and down by moving the carrier gas intake conduit 5 up and down via the supporting lifting device.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Inorganic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)

Abstract

The present invention discloses a method for carrying out phosphide in-situ injection synthesis by carrier gas, relating to a synthetic method of semiconductor crystal: step A, shielding inert gas is introduced into a furnace body through a carrier gas intake conduit; step B, a crucible is heated in the furnace body to melt a pre-synthesized raw material in the crucible; step C, the heated shielding inert gas is introduced into the furnace body through the carrier gas intake conduit; step D, a phosphorus source furnace loaded with red phosphorus is moved downwards until an injection conduit of the phosphorus source furnace is submerged in the melt; step E, the red phosphorus is heated by the phosphorus source furnace to produce phosphorus gas, and the phosphorus gas is mixed with the shielding inert gas and then injected into the melt through the injection conduit, and the phosphorus gas reacts with the melt to produce phosphide; and step F, each device is turned off after the synthesis is finished. In the present invention in the synthesis process, the shielding inert gas is introduced through the carrier gas intake conduit to enable the phosphorus gas to be stably injected into the melt, so that the melt is prevented from being sucked back into the phosphorus source furnace after the volatile element gas is completely absorbed.

Description

    CROSS-REFERENCE TO RELATED APPLICATIONS
  • This application claims priority to PCT Application No. PCT/CN2017/115468, filed on Dec. 11, 2017, which claims priority to Chinese Patent Application No. 201711298581.1, filed on Dec. 8, 2017, and each application is hereby incorporated by reference in its entirety.
    • TECHNICAL FIELD
  • The invention relates to a synthesis method of semiconductor crystal, in particular to a synthesis method of compound crystal material with volatile elements, such as indium phosphide, gallium phosphide and the like.
    • BACKGROUND ART
  • The compounds containing elements such as phosphorus or sulfur are widely used in the electronic industry, and they are important compound semiconductor materials such as indium phosphide and gallium phosphide. Because of the unique physical characteristics, these materials are widely used in many high-tech fields such as terahertz, optical communication, microwave, millimeter wave devices, radiation-resistant solar cells, etc. Therefore, compound semiconductor materials containing elements such as phosphorus or sulfur have been paid more and more attention.
  • Compounds containing elements such as phosphorus or sulfur are difficult to prepare due to their high dissociation pressures (e.g., 2.75 MPa for indium phosphide and 3.2 MPa for gallium phosphide). The current mainstream technologies are the Horizontal Bridgman/Horizontal Gradient Freeze (HB/HGF) and the injection synthesis method, but both of them have a problem of the explosion of the quartz sealing member, which makes the threshold and cost of synthetically preparing these materials high. The injection synthesis of phosphide is an efficient and rapid method for the synthesis of compounds, but due to strong reaction between gas and melt, suck-back easily occurs and thus leads to the explosion of phosphorus containers, which seriously affects the popularization and application of the method.
    • SUMMARY OF THE INVENTION
  • The problem to be solved by the invention is to provide a method for carrying out phosphide in-situ injection synthesis by carrier gas, wherein a shielding inert gas is used as carrier gas, and phosphorus gas in a phosphorus source furnace is injected into the melt in a crucible to synthesize phosphide, so that the melt is prevented from being sucked back into the phosphorus source furnace after the volatile element gas is completely absorbed.
  • In order to solve the above technical problem, the technical solution adopted by the invention is as follows: a method for carrying out phosphide in-situ injection synthesis by carrier gas, which is characterized by including the following steps of:
  • step A, introducing shielding inert gas into a furnace body through a carrier gas intake conduit, and the shielding inert gas is stopped being introduced when the pressure in the furnace body reaching a preset pressure is detected;
  • step B, heating the crucible in the furnace body to melt the pre-synthesized raw material in the crucible until the temperature required for phosphide synthesis is reached;
  • step C, introducing the carrier gas into the furnace body through a carrier gas intake conduit, and meanwhile opening and adjusting a carrier gas exhaust conduit so that the injection amount of the carrier gas is equal to the outflow amount of the gas;
  • step D, moving the phosphorus source furnace loaded with red phosphorus downwards until the injection conduit on the phosphorus source furnace is submerged in the melt and lowered close to the bottom of the crucible;
  • step E, heating the red phosphorus by the phosphorus source furnace to produce phosphorus gas, and mixing the phosphorus gas with the carrier gas and then injecting it into the melt through the injection conduit, and the phosphorus gas reacts with the melt to synthesize phosphide; and
  • step F, after the synthesis is finished, slowly lifting and turning off the phosphorus source furnace, and then stopping introducing the carrier gas into the furnace body, and finally stopping heating the crucible.
  • The invention has the beneficial technical effects: 1, in the synthesis process of phosphide, the carrier gas (shielding inert gas such as nitrogen or argon) is introduced through the carrier gas intake conduit, such that the carrier gas enables phosphorus gas to be stably injected into the melt to prevent the melt from being sucked back into the phosphorus source furnace after volatile element gas is completely absorbed; 2, a phosphorus gas absorber is added so that the phosphorus gas can be prevented from polluting the environment; and 3, the whole process is stable, and the synthesis efficiency is high, and the explosion phenomenon of the volatile gas carrier is unlikely to occur. The present invention will now be described in detail with reference to the accompanying drawings.
    • BRIEF DESCRIPTION OF THE DRAWINGS
  • FIG. 1 is a schematic view showing an internal structure of a furnace body in a method for carrying out phosphide in-situ injection synthesis by carrier gas according to the present invention; and
  • FIG. 2 is a schematic structural view of a phosphorus source furnace and a gas heating device of FIG. 1.
  • Throughout the drawings: 1 is a furnace body, 2 is a crucible, 3 is a crucible heating device, 4 is a phosphorus source furnace, 4-1 is a solid phosphorus loader, 4-2 is a thermal insulating sleeve, 4-3 is a heating wire, 4-4 is an injection conduit, 5 is a carrier gas intake conduit, 6 is a carrier gas exhaust conduit, 7 is a first pressure reducing valve, 8 is a first flow meter, 9 is a second pressure reducing valve, 10 is a second flow meter, 11 is a pressure gauge, 12 is a phosphorus absorber, 13 is a carrier gas heating device, 13-1 is a carrier gas heating conduit, 13-2 is a carrier gas heating and thermal insulating cavity, 13-3 is a carrier gas heating wire, 13-4 is a carrier gas injection conduit, 13-5 is a carrier gas heating multi-tube conduit, 14 is an observation window, 15 is a heat preserving device, 16 is a connecting sleeve, and 17 is a heat insulating layer.
    •  DETAILED DESCRIPTION OF THE INVENTION
  • The invention provides a method for carrying out phosphide in-situ injection synthesis by carrier gas, wherein the carrier gas is used for stably injecting phosphorus gas into melt so as to synthesize phosphide, and the melt can be prevented from being sucked back into a phosphorus source furnace.
    • Embodiment 1
  • Step A, shielding inert gas was introduced into a furnace body 1 through a carrier gas intake conduit 5, and the shielding inert gas was stopped being introduced when the pressure in the furnace body 1 reaching a preset pressure was detected. The preset pressure set in the step was greater than the dissociation pressure required to synthesize the compound melt.
  • In this embodiment, the carrier gas intake conduit 5 was communicated with a phosphorus source furnace 4, and the shielding inert gas (nitrogen or argon) and the carrier gas (nitrogen or argon) both entered the furnace body 1 through the phosphorus source furnace 4.
  • Step B, a crucible 2 in the furnace body 1 was heated to melt the pre-synthesized raw material in the crucible 2 until the temperature required for phosphide synthesis was reached.
  • Step C, the carrier gas was introduced into the furnace body 1 through the carrier gas intake conduit 5, and meanwhile a carrier gas exhaust conduit 6 was opened and adjusted so that the injection amount of the carrier gas was equal to the outflow amount of the gas. In the step, the temperature of the carrier gas introduced was 850° C. −900° C.
  • A first pressure reducing valve 7 and a first flow meter 8 were arranged on the carrier gas intake conduit 5, and the first pressure reducing valve 7 and the first flow meter 8 were located outside the furnace body 1. A second pressure reducing valve 9 and a second flow meter 10 were arranged on the carrier gas exhaust conduit 6, and the second pressure reducing valve 9 and the second flow meter 10 were located outside the furnace body 1. By arranging the pressure reducing valve and the flow meter, the flow rate and the charging pressure of the carrier gas could be controlled, and the pressure of the charged carrier gas ought to be greater than the pressure inside the furnace body 1.
  • The gas discharged from the carrier gas exhaust conduit 6 was introduced into a phosphorus absorber 12 loaded with high-purity cooling water to absorb unreacted phosphorus gas of step E, so that the environment was prevented from being polluted, and the discharged phosphorus which cooled into a solid could be recycled.
  • Step D, the phosphorus source furnace 4 loaded with red phosphorus was moved down until an injection conduit 4-4 of the phosphorus source furnace 4 was submerged in the melt and it was lowered close to the bottom of the crucible 2.
  • Step E, the red phosphorus was heated by the phosphorus source furnace 4 to produce phosphorus gas; the phosphorus gas was mixed with the carrier gas, and then injected into the melt through the injection conduit 4-4; and the phosphorus gas reacted with the melt to synthesize phosphide.
  • And step F, after the synthesis was finished, the phosphorus source furnace 4 was slowly lifted and turned off, and then the carrier gas was stopped being introduced into the furnace body 1, and finally the crucible 2 was stopped being heated.
    • Embodiment 2
  • Step A, shielding inert gas was introduced into a furnace body 1 through a carrier gas intake conduit 5, and the shielding inert gas was stopped being introduced when the pressure in the furnace body 1 reaching a preset pressure was detected. The preset pressure set in the step was greater than the dissociation pressure required to synthesize the compound melt.
  • Unlike embodiment 1, in this embodiment, the carrier gas intake conduit 5 was communicated with a carrier gas heating device 13, which was communicated with a phosphorus source furnace 4, and the shielding inert gas and the carrier gas entered the furnace body 1 through the carrier gas intake conduit 5, the carrier gas heating device 13 and the phosphorus source furnace 4.
  • Step B, a crucible 2 in the furnace body 1 was heated to melt the pre-synthesized raw material in the crucible 2 until the temperature required for phosphide synthesis was reached.
  • Step C, the carrier gas was introduced into the furnace body 1 through the carrier gas intake conduit 5, and meanwhile a carrier gas exhaust conduit 6 was opened and adjusted so that the injection amount of the carrier gas was equal to the outflow amount of the gas. In the step, the carrier gas was heated by the carrier gas heating device 13 so that the temperature of the heated carrier gas was 850° C. −900° C.
  • A first pressure reducing valve 7 and a first flow meter 8 were arranged on the carrier gas intake conduit 5, and the first pressure reducing valve 7 and the first flow meter 8 were located outside the furnace body 1. A second pressure reducing valve 9 and a second flow meter 10 were arranged on the carrier gas exhaust conduit 6, and the second pressure reducing valve 9 and the second flow meter 10 were located outside the furnace body 1. By arranging the pressure reducing valve and the flow meter, the flow rate and the charging pressure of the carrier gas could be controlled, and the pressure of the charged carrier gas ought to be greater than the pressure inside the furnace body 1.
  • The gas discharged from the carrier gas exhaust conduit 6 was introduced into a phosphorus absorber 12 loaded with high-purity cooling water to absorb unreacted phosphorus gas of step E, so that the environment was prevented from being polluted, and the discharged phosphorus which cooled into a solid could be recycled.
  • Step D, the phosphorus source furnace 4 loaded with red phosphorus and the carrier gas heating device 13 were moved down until an injection conduit 4-4 of the phosphorus source furnace 4 was submerged in the melt and they were lowered close to the bottom of the crucible 2.
  • Step E, the red phosphorus was heated by the phosphorus source furnace 4 to produce phosphorus gas; the phosphorus gas was mixed with the carrier gas, and then injected into the melt through the injection conduit 4-4; and the phosphorus gas reacted with the melt to synthesize phosphide. The carrier gas and the unreacted phosphorus gas overflowed the melt into a furnace cavity of the furnace body 1.
  • And step F, after the synthesis was finished, the phosphorus source furnace 4 was slowly lifted and turned off, and then the carrier gas was stopped being introduced into the furnace body 1, and finally the crucible 2 was stopped being heated.
  • In the above embodiments, the shielding inert gas and the carrier gas are argon or nitrogen.
  • Referring to FIGS. 1 and 2, in the present invention, a crucible 2 is arranged at the bottom of a furnace cavity of a furnace body 1; a crucible heating device 3 is arranged outside the crucible 2; a heat preserving device 15 is arranged between the furnace body 1 and the crucible heating device 3; a phosphorus source furnace 4 is arranged above the crucible 2; a carrier gas intake conduit 5 and a carrier gas exhaust conduit 6 are arranged on the furnace body 1; the carrier gas intake conduit 5 is communicated with the phosphorus source furnace 4 through the furnace body 1; and the carrier gas exhaust conduit 6 is communicated with the furnace cavity of the furnace body 1.
  • A pressure gauge 11 is provided on the furnace body 1 for easy observation of the pressure in the furnace. A viewing window 14 is provided on the furnace body 1 for easy viewing of the synthesis process.
  • The structure of the phosphorus source furnace 4 includes a solid phosphorus loader 4-1, a thermal insulating sleeve 4-2 positioned outside the solid phosphorus loader 4-1, a heating wire 4-3 arranged in the thermal insulating sleeve 4-2, and an injection conduit 4-4 for communicating the solid phosphorus loader 4-1 with the melt in the crucible 2.
  • The carrier gas intake conduit 5 is provided with a gas heating device 13, which is positioned in the furnace cavity of the furnace body 1. The structure of the gas heating device 13 includes a carrier gas heating conduit 13-1 with a carrier gas heating heat preserving cavity 13-1, a carrier gas heating wire 13-3 arranged on the carrier gas heating conduit 13-1, and a carrier gas injection conduit 13-4 for communicating the carrier gas heating conduit 13-1 with the phosphorus source furnace 4. A carrier gas heating multi-tube conduit 13-5 is arranged in the carrier gas heating conduit 13-1. The phosphorus source furnace 4 and the carrier gas heating device 13 are arranged in a connecting sleeve 16, and an insulating layer 17 is further arranged between the phosphorus source furnace 4 and the carrier gas heating device 13. With the arrangement of the connecting sleeve 16, the phosphorus source furnace 4 is integrated with the carrier gas heating device 13, and the carrier gas intake conduit 5 is connected to the connecting sleeve 16. The phosphorus source furnace 4 and the carrier gas heating device 13 are driven to move up and down by moving the carrier gas intake conduit 5 up and down via the supporting lifting device.
  • Finally, it should be noted that the above embodiments are only intended to illustrate and not to limit the technical solution of the present invention; although the present invention has been described in detail with reference to preferred embodiments thereof, it will be understood by those skilled in the art that modifications may be made in the specific embodiments of the present invention or equivalents may be substituted for some technical features; and they are intended to be within the scope of the claimed technical solution of the present invention without departing from the spirit of the technical solution of the present invention.

Claims (9)

1. A method for carrying out phosphide in-situ injection synthesis by carrier gas, characterized by comprising the following steps of:
step A, introducing shielding inert gas into a furnace body through a carrier gas intake conduit, and stopping introducing the shielding inert gas when the pressure in the furnace body reaching a preset pressure is detected;
step B, heating a crucible in the furnace body to melt a pre-synthesized raw material in the crucible until the temperature required for phosphide synthesis is reached;
step C, introducing the carrier gas into the furnace body through the carrier gas intake conduit, and meanwhile opening and adjusting a carrier gas exhaust conduit to enable the injection amount of the carrier gas to be equal to the outflow amount of the gas;
step D, moving a phosphorus source furnace loaded with red phosphorus downwards until an injection conduit of the phosphorus source furnace is submerged in the melt and lowered close to the bottom of the crucible;
step E, heating the red phosphorus with the phosphorus source furnace to produce phosphorus gas, and mixing the phosphorus gas with the carrier gas and then injecting it into the melt through the injection conduit, and the phosphorus gas reacts with the melt to synthesize phosphide; and
step F, after the synthesis is finished, slowly lifting and turning off the phosphorus source furnace and then stopping introducing the carrier gas into the furnace body, and finally stopping heating the crucible;
wherein, in step A, the carrier gas intake conduit is communicated with the phosphorus source furnace, and the shielding inert gas enters the furnace body through the carrier gas intake conduit and the phosphorus source furnace.
2. The method for carrying out phosphide in-situ injection synthesis by carrier gas according to claim 1, characterized in that the preset pressure in step A is greater than a dissociation pressure required to synthesize the compound melt.
3. (canceled)
4. The method for carrying out phosphide in-situ injection synthesis by carrier gas according to claim 1, characterized in that in step C the temperature of the carrier gas introduced into the furnace body is 850° C. −900° C.
5. The method for carrying out phosphide in-situ injection synthesis by carrier gas according to claim 1, characterized in that in step C the carrier gas is heated through a carrier gas heating device arranged in the furnace body, and the temperature of the heated carrier gas is 850° C. −900° C., the carrier gas intake conduit is communicated with the carrier gas heating device, the carrier gas heating device is communicated with the phosphorus source furnace, and the shielding inert gas and the carrier gas enter the furnace body through the carrier gas intake conduit, the carrier gas heating device and the phosphorus source furnace.
6. The method for carrying out phosphide in-situ injection synthesis by carrier gas according to claim 1, characterized in that in step C the gas discharged from the carrier gas exhaust conduit is introduced into a phosphorus absorber loaded with high-purity cooling water.
7. The method for carrying out phosphide in-situ injection synthesis by carrier gas according to claim 1, characterized in that the shielding inert gas and the carrier gas are argon or nitrogen.
8. The method for carrying out phosphide in-situ injection synthesis by carrier gas according to claim 1, characterized in that the crucible is arranged at the bottom of a furnace cavity of the furnace body; a crucible heating device is arranged outside the crucible; a thermal insulating device is arranged between the furnace body and the crucible heating device; the phosphorus source furnace is positioned above the crucible; the carrier gas intake conduit and the carrier gas exhaust conduit are arranged on the furnace body; the carrier gas intake conduit is communicated with the phosphorus source furnace through the furnace body;
and the carrier gas exhaust conduit is communicated with the furnace cavity of the furnace body. 9 (Original) The method for carrying out phosphide in-situ injection synthesis by carrier gas according to claim 8, characterized in that the structure of the phosphorus source furnace comprises a solid phosphorus loader, a thermal insulating sleeve located outside the solid phosphorus loader, a heating wire arranged in the thermal insulating sleeve, and an injection conduit for communicating the solid phosphorus loader with the melt in the crucible.
10. The method for carrying out phosphide in-situ injection synthesis by carrier gas according to claim 9, characterized in that the carrier gas heating device is provided on the carrier gas intake conduit; the carrier gas heating device is located in the furnace cavity of the furnace body; the structure of the carrier gas heating device comprises a carrier gas heating conduit having a carrier gas heating and thermal insulating cavity, a carrier gas heating wire arranged on the carrier gas heating conduit, and a carrier gas injection conduit for communicating the inside of the carrier gas heating conduit with the phosphorus source furnace.
US16/475,831 2017-12-08 2017-12-11 Method for carrying out phosphide in-situ injection synthesis by carrier gas Active US10648100B1 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
CN201711298581 2017-12-08
CN201711298581.1A CN108358180B (en) 2017-12-08 2017-12-08 Phosphide injection synthetic method in situ is carried out using carrying gas
CN201711298581.1 2017-12-08
PCT/CN2017/115468 WO2019109366A1 (en) 2017-12-08 2017-12-11 Method for in-situ injection and synthesis of phosphide by using bearing gas

Publications (2)

Publication Number Publication Date
US10648100B1 US10648100B1 (en) 2020-05-12
US20200157704A1 true US20200157704A1 (en) 2020-05-21

Family

ID=63009893

Family Applications (1)

Application Number Title Priority Date Filing Date
US16/475,831 Active US10648100B1 (en) 2017-12-08 2017-12-11 Method for carrying out phosphide in-situ injection synthesis by carrier gas

Country Status (4)

Country Link
US (1) US10648100B1 (en)
JP (1) JP6896084B2 (en)
CN (1) CN108358180B (en)
WO (1) WO2019109366A1 (en)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109402722B (en) * 2018-12-14 2020-09-01 中国电子科技集团公司第十三研究所 Device and method for synthesizing continuous VGF crystal growth by trans-injection
CN112429708B (en) * 2020-11-24 2022-06-21 中国电子科技集团公司第十三研究所 Method for purifying non-metal semiconductor material
JP2024500256A (en) * 2020-12-23 2024-01-09 中国電子科技集団公司第十三研究所 Semiconductor phosphide injection synthesis system and control method
CN113512755B (en) * 2021-07-06 2022-10-04 中国电子科技集团公司第十三研究所 Immersion phosphide synthesizing and growing device under magnetic field
CN113502546B (en) * 2021-07-06 2022-08-19 中国电子科技集团公司第十三研究所 Method for synthesizing and continuously growing phosphide in magnetic field
CN115198368B (en) * 2022-07-15 2024-08-13 中国电子科技集团公司第十三研究所 Semiconductor compound injection synthesis method

Family Cites Families (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3577405D1 (en) * 1984-12-28 1990-06-07 Sumitomo Electric Industries METHOD FOR PRODUCING POLYCRYSTALS FROM SEMICONDUCTOR CONNECTIONS AND DEVICE FOR CARRYING OUT THE SAME.
JPS61222911A (en) * 1985-03-28 1986-10-03 Toshiba Corp Synthesis of phosphorated compound
JPS62197306A (en) * 1986-02-20 1987-09-01 Agency Of Ind Science & Technol Production of phosphorus compound semiconductor
JP2539841B2 (en) * 1987-08-11 1996-10-02 株式会社ジャパンエナジー Crystal manufacturing method
JPH01242138A (en) * 1988-03-22 1989-09-27 Hitachi Cable Ltd Synthetic method for compound semiconductor
US5431125A (en) * 1991-06-14 1995-07-11 The United States Of America As Represented By The Secretary Of The Air Force Twin-free crystal growth of III-V semiconductor material
US5869398A (en) 1997-12-19 1999-02-09 Northern Telecom Limited Etching of indium phosphide materials for microelectronics fabrication
FR2930786B1 (en) * 2008-05-05 2010-12-31 Commissariat Energie Atomique PROCESS FOR THE PREPARATION OF LUMINESCENT NANOCRYSTALS, NANOCRYSTALS OBTAINED AND THEIR USES
CN102628180A (en) 2012-04-23 2012-08-08 南京金美镓业有限公司 Preparation method of high-purity indium phosphide polycrystalline rod
CN102602902A (en) * 2012-04-23 2012-07-25 南京金美镓业有限公司 High-pressure furnace for preparing indium phosphide
CN102965734A (en) * 2012-12-04 2013-03-13 中国电子科技集团公司第十三研究所 Rapid synthesis method of indium phosphide polycrystalline material and multi-tubular quartz phosphorus bubble thereof
CN105543949B (en) * 2016-03-10 2018-02-13 中国电子科技集团公司第十三研究所 Inject the preparation method of the continuous VGF/VB growth compounds semiconductor monocrystal of fabricated in situ
CN105568363B (en) * 2016-03-10 2018-07-31 中国电子科技集团公司第十三研究所 A kind of compound in situ synthesizes the VGF pressure furnaces of continuous crystal growth
CN106381524A (en) 2016-10-21 2017-02-08 北京鼎泰芯源科技发展有限公司 Observation window device based on in-situ synthesis method for InP single crystal furnace

Also Published As

Publication number Publication date
WO2019109366A1 (en) 2019-06-13
CN108358180A (en) 2018-08-03
US10648100B1 (en) 2020-05-12
JP6896084B2 (en) 2021-06-30
JP2020536827A (en) 2020-12-17
CN108358180B (en) 2019-08-02

Similar Documents

Publication Publication Date Title
US10648100B1 (en) Method for carrying out phosphide in-situ injection synthesis by carrier gas
WO2021098347A1 (en) System for preparing indium phosphide crystal from indium phosphorus mixture
US12116690B2 (en) Process for synthesizing indium phosphide by liquid phosphorus injection method
CN106381525B (en) A kind of device of the reduction InP crystal twin based on VGF method
WO2020199843A1 (en) Device for growing materials in supercritical fluid and material growth method
CN206204482U (en) A kind of device of the reduction InP crystal twins based on VGF methods
CN103541008A (en) Growth method and growth device of large-size gallium oxide single crystal
CN104451858A (en) Multifunctional crystal growth system for high-pressure in-situ synthesis
CN102965734A (en) Rapid synthesis method of indium phosphide polycrystalline material and multi-tubular quartz phosphorus bubble thereof
US20200149185A1 (en) Reflective screen of a monocrystal growth furnace and the monocrystal growth furnace
CN212895088U (en) System for synthesizing indium phosphide by liquid phosphorus injection method
CN204237887U (en) Situ high pressure synthesizes multi-functional crystal growth system
CN112663134A (en) Double-temperature-zone independently controlled silicon carbide single crystal growth device and growth method
CN105714372A (en) Crystal growing device
US20240352624A1 (en) Apparatus and method for synthesizing and continuously growing phosphide in magnetic field in immersion fashion
KR20110093856A (en) Using boron-containing compounds, gasses and fluids during ammonothermal growth of group-iii nitride crystals
CN103950909A (en) Preparation method of zinc phosphide
CN101879604A (en) Preparation method and application of metallic indium nanometer particle ink
CN212223145U (en) Pressure control system for VGF (vacuum vapor deposition) process of indium phosphide single crystal
CN207210579U (en) A kind of preparation facilities of semi-insulating GaAs polycrystalline carbon dope
CN110512281B (en) Method for rapidly preparing silicon carbide
CN209779044U (en) Apparatus for growing material in supercritical fluid
US20130029278A1 (en) Method for synthesizing group ii-vi compound semiconductor polycrystals
CN214529324U (en) Carbon doping device for growing semi-insulating gallium arsenide single crystal
CN103603038B (en) There is the light auxiliary MOCVD reactor of horizontal porous spray equipment

Legal Events

Date Code Title Description
FEPP Fee payment procedure

Free format text: ENTITY STATUS SET TO UNDISCOUNTED (ORIGINAL EVENT CODE: BIG.); ENTITY STATUS OF PATENT OWNER: SMALL ENTITY

FEPP Fee payment procedure

Free format text: ENTITY STATUS SET TO SMALL (ORIGINAL EVENT CODE: SMAL); ENTITY STATUS OF PATENT OWNER: SMALL ENTITY

STCF Information on status: patent grant

Free format text: PATENTED CASE

MAFP Maintenance fee payment

Free format text: PAYMENT OF MAINTENANCE FEE, 4TH YR, SMALL ENTITY (ORIGINAL EVENT CODE: M2551); ENTITY STATUS OF PATENT OWNER: SMALL ENTITY

Year of fee payment: 4