WO2010038407A1 - 炭化珪素単結晶基板 - Google Patents
炭化珪素単結晶基板 Download PDFInfo
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- WO2010038407A1 WO2010038407A1 PCT/JP2009/004933 JP2009004933W WO2010038407A1 WO 2010038407 A1 WO2010038407 A1 WO 2010038407A1 JP 2009004933 W JP2009004933 W JP 2009004933W WO 2010038407 A1 WO2010038407 A1 WO 2010038407A1
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- silicon carbide
- single crystal
- carbide single
- crystal substrate
- particles
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- 239000000758 substrate Substances 0.000 title claims abstract description 156
- 239000013078 crystal Substances 0.000 title claims abstract description 144
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 title claims abstract description 141
- 229910010271 silicon carbide Inorganic materials 0.000 title claims abstract description 140
- 239000002245 particle Substances 0.000 claims abstract description 114
- 238000000034 method Methods 0.000 claims description 70
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- 238000005498 polishing Methods 0.000 claims description 29
- 239000003002 pH adjusting agent Substances 0.000 claims description 16
- 239000003795 chemical substances by application Substances 0.000 claims description 15
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 14
- 238000004381 surface treatment Methods 0.000 claims description 14
- 239000004744 fabric Substances 0.000 claims description 13
- -1 fluorine ions Chemical class 0.000 claims description 13
- 239000010432 diamond Substances 0.000 claims description 11
- 229910003460 diamond Inorganic materials 0.000 claims description 11
- 239000007800 oxidant agent Substances 0.000 claims description 11
- 239000006061 abrasive grain Substances 0.000 claims description 10
- WQYVRQLZKVEZGA-UHFFFAOYSA-N hypochlorite Chemical compound Cl[O-] WQYVRQLZKVEZGA-UHFFFAOYSA-N 0.000 claims description 10
- 239000007787 solid Substances 0.000 claims description 9
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 8
- 239000007864 aqueous solution Substances 0.000 claims description 8
- 229910052710 silicon Inorganic materials 0.000 claims description 8
- 239000010703 silicon Substances 0.000 claims description 8
- 229910052684 Cerium Inorganic materials 0.000 claims description 5
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims description 5
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 claims description 5
- 229910052782 aluminium Inorganic materials 0.000 claims description 5
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 5
- GDTBXPJZTBHREO-UHFFFAOYSA-N bromine Substances BrBr GDTBXPJZTBHREO-UHFFFAOYSA-N 0.000 claims description 5
- 229910052794 bromium Inorganic materials 0.000 claims description 5
- 229910052801 chlorine Inorganic materials 0.000 claims description 5
- 239000000460 chlorine Substances 0.000 claims description 5
- 229910052731 fluorine Inorganic materials 0.000 claims description 5
- 239000011737 fluorine Substances 0.000 claims description 5
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 4
- 229910052804 chromium Inorganic materials 0.000 claims description 4
- 239000011651 chromium Substances 0.000 claims description 4
- 229910044991 metal oxide Inorganic materials 0.000 claims description 4
- 150000004706 metal oxides Chemical class 0.000 claims description 4
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 claims 1
- 239000002356 single layer Substances 0.000 claims 1
- 230000007547 defect Effects 0.000 abstract description 8
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- 238000004140 cleaning Methods 0.000 description 54
- 239000004065 semiconductor Substances 0.000 description 39
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 21
- 230000002159 abnormal effect Effects 0.000 description 17
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- 239000000126 substance Substances 0.000 description 10
- 239000007788 liquid Substances 0.000 description 9
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 8
- 239000012535 impurity Substances 0.000 description 8
- 238000001514 detection method Methods 0.000 description 7
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 239000010409 thin film Substances 0.000 description 6
- 238000005406 washing Methods 0.000 description 6
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 4
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 4
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 4
- ZMIGMASIKSOYAM-UHFFFAOYSA-N cerium Chemical compound [Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce] ZMIGMASIKSOYAM-UHFFFAOYSA-N 0.000 description 4
- 239000010408 film Substances 0.000 description 4
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- 239000004745 nonwoven fabric Substances 0.000 description 4
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- 230000003746 surface roughness Effects 0.000 description 3
- 239000002253 acid Substances 0.000 description 2
- 230000002378 acidificating effect Effects 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 229910021529 ammonia Inorganic materials 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 239000012467 final product Substances 0.000 description 2
- 238000007654 immersion Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000007790 scraping Methods 0.000 description 2
- 150000003377 silicon compounds Chemical class 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 description 1
- 238000003763 carbonization Methods 0.000 description 1
- 229910000423 chromium oxide Inorganic materials 0.000 description 1
- UOUJSJZBMCDAEU-UHFFFAOYSA-N chromium(3+);oxygen(2-) Chemical class [O-2].[O-2].[O-2].[Cr+3].[Cr+3] UOUJSJZBMCDAEU-UHFFFAOYSA-N 0.000 description 1
- 239000008119 colloidal silica Substances 0.000 description 1
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- 238000005516 engineering process Methods 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
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- 238000000227 grinding Methods 0.000 description 1
- QWPPOHNGKGFGJK-UHFFFAOYSA-N hypochlorous acid Chemical compound ClO QWPPOHNGKGFGJK-UHFFFAOYSA-N 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
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Images
Classifications
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- 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
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
- H01L21/306—Chemical or electrical treatment, e.g. electrolytic etching
- H01L21/30625—With simultaneous mechanical treatment, e.g. mechanico-chemical polishing
-
- 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
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
- H01L21/304—Mechanical treatment, e.g. grinding, polishing, cutting
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B37/00—Lapping machines or devices; Accessories
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B37/00—Lapping machines or devices; Accessories
- B24B37/04—Lapping machines or devices; Accessories designed for working plane surfaces
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B33/00—Severing cooled glass
-
- 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
- C30B29/36—Carbides
-
- 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
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02002—Preparing wafers
- H01L21/02005—Preparing bulk and homogeneous wafers
- H01L21/02008—Multistep processes
-
- 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
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02002—Preparing wafers
- H01L21/02005—Preparing bulk and homogeneous wafers
- H01L21/02008—Multistep processes
- H01L21/0201—Specific process step
- H01L21/02024—Mirror polishing
-
- 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
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02041—Cleaning
- H01L21/02043—Cleaning before device manufacture, i.e. Begin-Of-Line process
- H01L21/02052—Wet cleaning only
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
- H01L29/12—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
- H01L29/16—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed including, apart from doping materials or other impurities, only elements of Group IV of the Periodic Table
- H01L29/1608—Silicon carbide
-
- 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
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
- Y10T428/24355—Continuous and nonuniform or irregular surface on layer or component [e.g., roofing, etc.]
- Y10T428/24372—Particulate matter
Definitions
- the present invention relates to a silicon carbide single crystal substrate, and particularly to a silicon carbide single crystal substrate having a high surface cleanliness.
- silicon carbide (SiC) single crystal materials are expected as semiconductor device materials because they have excellent semiconductor properties such as high power density and low loss. In particular, it is attracting attention as a future power electronics semiconductor device.
- a semiconductor device is generally formed by epitaxially growing a plurality of semiconductor layers on one surface of a semiconductor substrate. Since the semiconductor layer is a thin film, it is desirable that one surface of the semiconductor substrate be polished so as not to be uneven, and that a cleaning process be performed so that no impurity particles are present. When impurity particles adhere and remain on the surface of the semiconductor substrate, it becomes difficult to form an epitaxially grown film to be formed without defects. In addition, the process yield in forming the surface oxide film is significantly reduced.
- Patent Document 1 relates to a method for cleaning a semiconductor substrate, and discloses a method for cleaning a semiconductor substrate (such as a silicon wafer) that combines an oxidation and reduction process and a rinsing process. This removes minute damage and metal impurities generated by processing the semiconductor substrate, and also removes impurities on the substrate including organic deposits and fine particles on the surface of the semiconductor substrate.
- a semiconductor substrate such as a silicon wafer
- Patent Document 2 relates to a nitride compound semiconductor, a method for cleaning the compound semiconductor, a manufacturing method thereof, and a substrate.
- a cleaning method suitable for the nitride compound semiconductor a cleaning liquid having a pH of 7.1 or more is disclosed. A cleaning method is disclosed.
- FIG. 4 is a flowchart showing an example of a manufacturing process of a conventional silicon carbide single crystal substrate.
- the manufacturing process of the silicon carbide single crystal substrate is roughly composed of a surface processing step S110, a cleaning step S120, and a surface inspection step S130.
- the surface inspection step S130 what has passed is shipped as a final silicon carbide single crystal substrate.
- the substrate that has been rejected in the surface inspection step S130 is returned to the surface processing step S110 again, the necessary surface processing is performed, the cleaning processing step S120 is performed, and then the surface inspection is performed again in the surface inspection step S130. Do. Passed substrates are shipped as final products, while rejected products continue the above cycle until they pass.
- the adhering particles are detected by scattering the incident light beam on the surface of the semiconductor substrate and visually inspecting it, or by surface inspection such as SurfScan (manufactured by Tencor).
- SurfScan manufactured by Tencor
- a detection method in which inspection is performed using an apparatus has been used.
- the adhering particles smaller than the wavelength of the incident light beam used for detection exceed the optical detection limit of this method and are not targeted for adhering particles to be removed.
- a semiconductor substrate in which such a small amount of attached particles remains is treated as a semiconductor substrate that has been subjected to a cleaning process.
- the residual adhered particles having a size exceeding the optical detection limit which could not be detected by the conventional method, may cause abnormal growth during epitaxial growth and still cause crystal defects in the thin film. It was.
- the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a silicon carbide single crystal substrate having a high surface cleanliness from which adhered particles causing crystal defects are removed.
- the present invention employs the following configuration. That is, (1) The second adhering particles having a density of 1 particle / cm 2 or less of the first adhering particles having a height of 100 nm or more adhering to one surface of the substrate and having a height of less than 100 nm adhering to the one surface of the substrate
- the silicon carbide single crystal substrate is characterized in that the density of the silicon carbide is 1500 pieces / cm 2 or less.
- the density of the second adhering particles is measured by performing a surface inspection using an atomic force microscope (AFM) before the surface processing step for reducing the adhering particles, according to (3).
- Silicon carbide single crystal substrate (5) The silicon carbide single crystal substrate according to (3) or (4), wherein the pH adjuster adjusts the pH of the surface of the silicon carbide single crystal substrate to 3 or less.
- the oxidizing agent is an aqueous solution containing at least one of sulfuric acid, chlorine, ozone, hypochlorite, fluorine ions, and bromine ions, as described in (7) or (8) Silicon carbide single crystal substrate.
- FIG. 1 is a flowchart showing an example of a manufacturing process of a silicon carbide single crystal substrate according to an embodiment of the present invention.
- the manufacturing process of a silicon carbide single crystal substrate according to an embodiment of the present invention is roughly configured from a surface processing step S10, a cleaning processing step S20, a surface inspection step S30, and a surface processing step S15 for reducing attached particles.
- the surface processing step S10 includes an end surface processing step S11, a rough processing step S12, a mirror polishing processing step S13, and a CMP processing surface treatment S14.
- the cleaning step S20 includes a rough cleaning step S21 and a shape inspection. It consists of S22 and final cleaning process S23.
- the surface inspection step S30 includes an optical surface inspection S31 and a surface inspection (atomic force surface inspection) S32 using an atomic force microscope (AFM).
- the silicon carbide single crystal substrate that has passed the atomic force type surface inspection S32 is shipped as a final product.
- the substrate rejected in the surface inspection step S30 is returned to the surface processing step S15 for reducing attached particles, and after performing the surface processing treatment, the cleaning processing step S20 is performed, and then the surface inspection is performed again in the surface inspection step S30. Do. Passed substrates are shipped as final products, while rejected products continue the above cycle until they pass.
- end face processing S11 is performed on a silicon carbide single crystal wafer (silicon carbide single crystal substrate) formed by cutting out a silicon carbide single crystal ingot formed by a sublimation method or the like. Specifically, the front and back end edges of the silicon carbide single crystal substrate cut at a substantially right angle are processed into an arc shape of about R50-200 ⁇ m by grinding or the like.
- rough processing S12 is performed on the surface of the silicon carbide single crystal substrate.
- the silicon carbide single crystal substrate is sandwiched between two upper and lower flat surface plates, and the two surface plates are rotated to face each other while supplying an abrasive, and the silicon carbide This is a process for improving the flatness by scraping the front and back of the single crystal substrate to adjust the thickness.
- mirror polishing S13 is performed on the surface of the silicon carbide single crystal substrate.
- the mirror polishing processing S13 is a processing method similar to the roughing processing, and a non-woven fabric or the like is pasted on the processing surfaces of the upper and lower surface plates, and a finer polishing agent is supplied, whereby the silicon carbide single crystal substrate In this process, the surface irregularities and scratches are removed to obtain an optically flat mirror surface.
- the CMP processing surface treatment S14 is a processing for removing fine scratches and processing damage layers remaining on the surface of the silicon carbide single crystal substrate by surface processing by a chemical mechanical mechanism.
- a CMP processing surface treatment S14 is a processing for removing fine scratches and processing damage layers remaining on the surface of the silicon carbide single crystal substrate by surface processing by a chemical mechanical mechanism.
- several silicon carbide single crystal substrates are flatly attached to a flat table (plate) made of ceramic or the like with wax or the like, and the processing liquid is supplied to a rotating surface plate to which a nonwoven fabric or the like is attached.
- this is a process of removing the surface of the silicon carbide single crystal substrate very thinly by pressing and rotating the plane of the silicon carbide single crystal substrate through the plate.
- the surface damage of the silicon carbide single crystal substrate can be removed, and the silicon carbide single crystal substrate has a mirror shape.
- chromium oxide etc. are used for the processing liquid used by this surface treatment.
- the plate is removed from the processing machine, the processing liquid is removed, and then the mirror-like silicon carbide single crystal substrate is peeled off from the plate.
- the peeled mirror-like silicon carbide single crystal substrate is transferred to a cleaning container and subjected to a cleaning treatment step S20.
- the plate is attached to a single-sided processing machine, pure water is supplied and surface cleaning is performed for 5 minutes, and then the plate is removed from the machine and washed with water. Is peeled from the plate.
- a rough cleaning process S21 is performed on the mirror-like silicon carbide single crystal substrate.
- the rough cleaning process S21 uses a general RCA cleaning process as a semiconductor substrate cleaning method.
- the RCA cleaning is a method for cleaning a semiconductor substrate developed by RCA, and is a method for cleaning at a high temperature using a chemical solution containing hydrogen peroxide, alkali and acid.
- medical agent to be used, conditions, etc. differ with each semiconductor substrate manufacturer.
- the mirror-like silicon carbide single crystal substrate is sequentially immersed in the following chemical baths.
- the chemical tank is an acetone tank, methanol tank, pure water tank, SPM tank (sulfuric acid, hydrogen peroxide mixture), pure water tank, SC1 tank (aqueous mixture of ammonia and hydrogen peroxide), pure water tank, hydrofluoric acid tank, pure water tank.
- Water tank, SC2 tank aqueous solution of hydrochloric acid and hydrogen peroxide
- pure water tank, hydrofluoric acid tank, pure water tank, and IPA tank In each tank, the mirror-like silicon carbide single crystal substrate immersed therein is subjected to shaking, ultrasonic waves, or the like as necessary.
- the mirror-like silicon carbide single crystal substrate pulled up from the IPA tank is dried by subjecting the IPA to vapor drying.
- shape inspection S22 is performed.
- the flatness (GSBR or Warp) of the mirror-like silicon carbide single crystal substrate is measured using a flat nestester, and the final finished thickness is measured using an optical micrometer.
- the final cleaning process S22 is basically the same as the previous rough cleaning process S21, but the remaining particles such as the cleaning liquid and the number of times the liquid is used are managed to further increase the cleanliness.
- the mirror-like silicon carbide single crystal substrate subjected to the final cleaning process S23 is subjected to the following surface inspection process S30.
- optical surface inspection S31 is performed on the silicon carbide single crystal substrate.
- the optical surface inspection S31 is a conventional surface inspection method, mainly using naked eyes or visual observation using an optical microscope or SurfScan (manufactured by Tencor) to inspect surface scratches, cloudiness, adhered particles, and the like.
- the size (height and diameter) of the object to be measured is in principle at least the light wavelength (100 nm: 0.1 ⁇ m or more). Thereby, the magnitude
- the adhered particles having a height of 100 nm or more are referred to as first adhered particles. It is preferable that the density of the first attached particles is 1 particle / cm 2 or less. By setting the density of the first attached particles to 1 piece / cm 2 or less, abnormal growth during epitaxial growth caused by the first attached particles can be suppressed.
- atomic force type surface inspection S32 is performed by an atomic force microscope (AFM).
- the atomic force type surface inspection S32 is a surface inspection using an atomic force microscope (AFM), and particles having a height of 0.05 nm to 0.5 ⁇ m can be observed. Thereby, the magnitude
- the adhered particles having a height of less than 100 nm are referred to as second adhered particles.
- the density of the second adhering particles is preferably 1500 particles / cm 2 or less, and the density of the second adhering particles is more preferably 100 particles / cm 2 or less.
- the density of the second adhering particles is preferably 1500 particles / cm 2 or less, and the density of the second adhering particles is more preferably 100 particles / cm 2 or less.
- the material of the second attached particles is not particularly limited. Examples thereof include diamond particles contained in the abrasive and silicon compound particles generated from the substrate. As the size of the second adhered particles, many particles having a height of 0.5 to 2 nm are seen.
- the second adhered particles are adhered to the surface of the silicon carbide single crystal substrate in a chemically stable state. Therefore, there are many cases where the second attached particles cannot be completely removed only by the conventional cleaning process.
- Si, GaAs, InP, or the like is used as the substrate, the impurity particles (adhered particles) on the substrate surface do not adhere to the substrate surface in a chemically stable state, and the conventional cleaning process is performed. By applying, not only the first attached particles but also the second attached particles are easily removed.
- the silicon carbide single crystal substrate that passed the atomic force surface inspection S32 is shipped as the final product.
- the rejected silicon carbide single crystal substrate is subjected to a surface processing step S15 for reducing attached particles.
- the surface treatment processing step S15 for reducing attached particles is a step of reducing the density of the second attached particles by polishing the surface using an abrasive made of a polishing cloth impregnated with a pH adjuster and diamond abrasive grains.
- the surface treatment processing step S15 for reducing attached particles is a step of reducing the density of the second attached particles by polishing the surface using an abrasive made of a polishing cloth impregnated with a pH adjuster and diamond abrasive grains.
- the pH adjuster preferably adjusts the surface pH of the silicon carbide single crystal substrate to 3 or less, and more preferably 2 or less. By making the surface of the silicon carbide single crystal substrate acidic, it becomes easy to remove chemically attached second attached particles.
- the polishing cloth is further impregnated with an oxidizing agent, and the oxidizing agent is preferably an aqueous solution containing one or more of sulfuric acid, chlorine, ozone, hypochlorite, fluorine ions and bromine ions.
- the oxidizing agent is preferably an aqueous solution containing one or more of sulfuric acid, chlorine, ozone, hypochlorite, fluorine ions and bromine ions.
- the polishing cloth is further impregnated with a soft solid agent, and the soft solid agent preferably contains one or more metal oxides of silicon, aluminum, cerium, or chromium. Thereby, the 2nd adhesion particle adhering chemically stably can be removed.
- the surface processing is performed by combining the above components.
- mirror polishing is performed using a polishing cloth impregnated with a pH adjusting agent for adjusting the pH of the surface of the silicon carbide single crystal substrate to 2 or less and diamond abrasive grains.
- a polishing cloth impregnated with an oxidizing agent and a soft solid agent is used to perform a mirror surface treatment, and a pH adjuster is used to adjust the pH to 3 or less, and silicon, aluminum,
- a soft solid material containing one or more of cerium and chromium oxides is used, and one of sulfuric acid, chlorine, ozone, hypochlorite, fluorine ions and bromine ions is used as an oxidizing agent.
- mirror polishing is performed using an aqueous solution containing more than that.
- the surface inspection S32 using an atomic force microscope (AFM) is performed to measure the density of the second adhering particles, and then the adhering particle reducing surface processing step S15.
- the surface processing step S15 for reducing attached particles may be performed after the surface processing step S10.
- the density of the first attached particles having a height of 100 nm or more attached to one surface of the substrate is 1 particle / cm 2 or less, and attached to one surface of the substrate.
- the density of the second attached particles having a height of less than 100 nm is set to 1500 particles / cm 2 or less, so that abnormal growth during epitaxial growth caused by the second attached particles is suppressed, and the silicon carbide single crystal semiconductor Process yield can be improved.
- the silicon carbide single crystal substrate according to an embodiment of the present invention preferably has a configuration in which the density of the second attached particles is 100 particles / cm 2 or less, and since this is the configuration, the epitaxial growth caused by the second attached particles can be prevented. Abnormal growth can be suppressed, and the process yield of the silicon carbide single crystal semiconductor can be further improved.
- the silicon carbide single crystal substrate according to the embodiment of the present invention is subjected to a surface processing step S15 for reducing attached particles, in which the surface is polished using a polishing cloth impregnated with a pH adjusting agent and a polishing agent comprising diamond abrasive grains. Therefore, the abnormal growth during epitaxial growth caused by the second attached particles can be suppressed, and the process yield of the silicon carbide single crystal semiconductor can be improved.
- the silicon carbide single crystal substrate according to the embodiment of the present invention performs surface inspection S32 by an atomic force microscope (AFM) and measures the density of the second attached particles before the surface processing step S15 for reducing attached particles.
- AFM atomic force microscope
- the pH adjuster is configured to set the pH of the surface of the silicon carbide single crystal substrate to 3 or less, thereby suppressing abnormal growth during epitaxial growth caused by the second attached particles.
- the process yield of the silicon carbide single crystal semiconductor can be improved.
- the pH adjuster is configured to set the pH of the surface of the silicon carbide single crystal substrate to 2 or less, so that abnormal growth during epitaxial growth caused by the second attached particles is suppressed.
- the process yield of the silicon carbide single crystal semiconductor can be improved.
- the silicon carbide single crystal substrate according to the embodiment of the present invention has a structure in which the polishing cloth is further impregnated with an oxidizing agent and / or a soft solid agent, the abnormal growth during the epitaxial growth caused by the second attached particles is suppressed, and the carbonization is performed.
- the process yield of the silicon single crystal semiconductor can be improved.
- the silicon carbide single crystal substrate according to the embodiment of the present invention has a structure in which the soft solid agent contains one or more metal oxides of silicon, aluminum, cerium, or chromium. Abnormal growth can be suppressed and the process yield of the silicon carbide single crystal semiconductor can be improved.
- the silicon carbide single crystal substrate according to the embodiment of the present invention has a configuration in which the oxidizing agent is an aqueous solution containing at least one of sulfuric acid, chlorine, ozone, hypochlorite, fluorine ions, and bromine ions, the second Abnormal growth during epitaxial growth caused by the adhered particles can be suppressed, and the process yield of the silicon carbide single crystal semiconductor can be improved.
- the present invention will be specifically described based on examples. However, the present invention is not limited only to these examples.
- Example 1 A silicon carbide single crystal substrate (Example 1 sample) was manufactured using the manufacturing process of the silicon carbide single crystal substrate shown in the flowchart of FIG.
- ⁇ Surface treatment process> First, a (0001) 8 ° inclined substrate of a silicon carbide single crystal substrate having a diameter of about 50 mm ⁇ was prepared, and predetermined end face processing was performed. Next, the silicon carbide single crystal substrate is sandwiched between two upper and lower flat surface plates, and the two surface plates are rotated opposite to each other while supplying an abrasive, so that the front and back surfaces of the silicon carbide single crystal substrate are reversed. The thickness was adjusted by scraping to improve the flatness and rough processing was performed. Diamond abrasive grains were used as the processing abrasive grains.
- a nonwoven fabric or the like is pasted on the processing surfaces of the two upper and lower flat surface plates, a silicon carbide single crystal substrate is sandwiched between the two surface plates, and a finer abrasive is supplied while The surface plates were rotated opposite to each other, the front and back surfaces of the silicon carbide single crystal substrate were scraped, the thickness was adjusted, the flatness was improved, and a mirror polishing process was performed. At this time, finer diamond abrasive grains were used. Thereby, an optically flat mirror surface having a surface roughness Ra of about 5 nm was obtained.
- the plate was attached to a single-sided processing machine, and only pure water was supplied to perform surface cleaning for 5 minutes.
- the plate diameter was 380 ⁇
- the platen rotational speed was 60 rpm
- the pressure was 25 kPa on the silicon carbide single crystal substrate surface.
- the silicon carbide single crystal substrate was peeled from the plate.
- ⁇ Washing process> The exfoliated silicon carbide single crystal substrate was subjected to a rough cleaning treatment.
- RCA cleaning was used in which cleaning was performed at a high temperature using a chemical solution containing hydrogen peroxide, alkali and acid. Specifically, it was immersed sequentially in the following chemical baths, and rocking and ultrasonic waves were applied.
- the chemical tank is an acetone tank, methanol tank, pure water tank, SPM tank (sulfuric acid, hydrogen peroxide mixture), pure water tank, SC1 tank (aqueous mixture of ammonia and hydrogen peroxide), pure water tank, hydrofluoric acid tank, pure water tank.
- a water tank, SC2 tank (aqueous solution of hydrochloric acid and hydrogen peroxide), pure water tank, hydrofluoric acid tank, pure water tank, and IPA tank were used. After the immersion treatment in the IPA tank, the IPA was vapor-dried while being pulled up from the IPA tank, and dried. Next, after performing shape inspection using a flatness tester and an optical micrometer to confirm that the flatness is within an allowable range, a final cleaning process of RCA cleaning was performed in the same manner as the rough cleaning process.
- ⁇ Surface inspection process> First, a dark field visual inspection and an optical surface inspection by SurfScan (manufactured by Tencor) of the silicon carbide single crystal substrate subjected to the final cleaning treatment were performed. No scratches or cloudiness were observed on the silicon carbide single crystal substrate.
- SurfScan manufactured by Tencor
- FIG. 2 is a photograph of the surface of the silicon carbide single crystal substrate obtained by atomic force surface inspection.
- One residual adhered particle having a height of 1.2 nm was observed in the measurement region shown in FIG.
- the optical surface inspection which is a conventional surface inspection method, the atomic force surface inspection has been performed, and it has become clear that fine adhered particles that could not be detected conventionally remain.
- a surface processing process for reducing attached particles was performed using a polishing cloth impregnated with a polishing agent made of diamond abrasive grains and a pH adjuster.
- a surface processing process for reducing attached particles was performed using a polishing cloth impregnated with a polishing agent made of diamond abrasive grains and a pH adjuster.
- the pH of the surface of the silicon carbide single crystal substrate was adjusted to 1 with a pH adjuster. Then, after repeating the said washing
- FIG. 3 is a photograph of the surface of the silicon carbide single crystal substrate obtained by atomic force surface inspection. No adhering particles having a height of 0.5 to less than 100 nm were observed in the measurement region shown in FIG. Thus, by measuring the entire surface of the silicon carbide single crystal substrate with AFM, it was found that the density of adhered particles having a height of 0.5 or more and less than 100 nm was 100 particles / cm 2 .
- the surface roughness Ra of the silicon carbide single crystal substrate was 0.1 nm or less.
- a silicon carbide semiconductor was fabricated by epitaxially growing a silicon carbide single crystal thin film having a thickness of several to several tens of ⁇ m on this silicon carbide single crystal substrate.
- the abnormal growth points generated in this epitaxial growth process were 120 / cm 2 .
- Example 2 After completion of the surface processing step, a silicon carbide single crystal substrate (implemented in the same manner as in Example 1), except that the plate was attached to a single-sided processing machine and the surface cleaning time performed by supplying only pure water was 1 minute. Example 2 sample) was prepared.
- the surface of the silicon carbide single crystal substrate is adjusted so that the pH of the surface becomes 1, and a surface processing process for reducing attached particles (mirror polishing) After the treatment, the washing treatment process was repeated. Then, the surface inspection process was performed again.
- the surface of the silicon carbide single crystal substrate is not scratched or clouded. It was 1 piece (1 piece / cm 2 ) on the entire surface.
- the entire surface of the silicon carbide single crystal substrate was measured by AFM, and it was found that the density of adhered particles having a height of 0.5 to 100 nm was 1500 particles / cm 2 .
- a silicon carbide semiconductor was fabricated by epitaxially growing a silicon carbide single crystal thin film having a thickness of several to several tens of ⁇ m on this silicon carbide single crystal substrate.
- the abnormal growth point generated in this epitaxial growth process was 1700 / cm 2 .
- a silicon carbide single crystal substrate (Comparative Example 1 sample) was manufactured using the conventional manufacturing process of a silicon carbide single crystal substrate shown in the flowchart of FIG. First, after performing the surface processing step in the same manner as in Example 1, the plate was removed from the processing machine, the processing liquid was removed by washing with water, and then the silicon carbide single crystal substrate was peeled from the plate. Next, in the same manner as in Example 1, after performing a cleaning process including rough cleaning, shape inspection, and final cleaning, a surface inspection process was performed.
- the surface of the silicon carbide single crystal substrate is not scratched or clouded.
- the total number was 2 (2 / cm 2 ).
- the entire surface of the silicon carbide single crystal substrate was measured by AFM, and it was found that the density of attached particles having a height of 0.5 to 100 nm was 1 ⁇ 10 4 particles / cm 2 .
- a silicon carbide semiconductor was fabricated by epitaxially growing a silicon carbide single crystal thin film having a thickness of several to several tens of ⁇ m on this silicon carbide single crystal substrate.
- the abnormal growth point generated in this epitaxial growth process was 2.5 ⁇ 10 4 pieces / cm 2 .
- the present invention relates to a silicon carbide single crystal substrate having a high surface cleanliness, and the production of a high power power device, a high temperature resistant element material, a radiation resistant element material, a high frequency element material, etc. using the silicon carbide single crystal and the like. It can be used in the industries that use it.
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Abstract
Description
本願は、2008年9月30日に、日本に出願された特願2008-252731号に基づき優先権を主張し、その内容をここに援用する。
しかし、炭化珪素(SiC)化合物半導体の製造プロセスにおけるエピタキシャル成長を伴う製造プロセスにおいては、前記洗浄方法を用いて清浄化した半導体基板を用いても、依然としてエピタキシャル成長時に異常成長等が生じて、前記薄膜に結晶欠陥などを発生させる場合があった。
表面検査工程S130で不合格とされた基板は再び表面加工処理工程S110へ戻し、必要とされる表面加工処理を行って、洗浄処理工程S120を行った後、再び表面検査工程S130で表面検査を行う。合格した基板は最終品として出荷し、不合格品は、合格するまで上記のサイクルを続ける。
このような従来の方法では検出できなかった光学検出限界を超える大きさの付着粒子の残留が、エピタキシャル成長時に異常成長等を生じさせ、依然として前記薄膜に結晶欠陥などを発生させている可能性があった。
(1) 基板の一面に付着した高さが100nm以上の第1付着粒子の密度が1個/cm2以下とされ、かつ、前記基板の一面に付着した高さが100nm未満の第2付着粒子の密度が1500個/cm2以下とされていることを特徴とする炭化珪素単結晶基板。
(2) 前記第2付着粒子の密度が100個/cm2以下とされていることを特徴とする(1)に記載の炭化珪素単結晶基板。
(3) pH調整剤を含浸させた研磨布とダイヤモンド砥粒からなる研磨剤を用いて表面を研磨処理する付着粒子低減用表面加工処理工程を行って形成されてなることを特徴とする(1)または(2)に記載の炭化珪素単結晶基板。
(5) 前記pH調整剤が前記炭化珪素単結晶基板の表面のpHを3以下とすることを特徴とする(3)または(4)に記載の炭化珪素単結晶基板。
(6) 前記pH調整剤が前記炭化珪素単結晶基板の表面のpHを2以下とすることを特徴とする(3)~(5)のいずれかに記載の炭化珪素単結晶基板。
(8) 前記軟固形剤が珪素、アルミニウム、セリウムまたはクロムのいずれかの金属酸化物を一以上含有することを特徴とする(7)に記載の炭化珪素単結晶基板。
(9) 前記酸化剤が硫酸、塩素、オゾン、次亜塩素酸塩、フッ素イオン、臭素イオンのいずれかを一以上含有する水溶液であることを特徴とする(7)または(8)に記載の炭化珪素単結晶基板。
図1は、本発明の実施形態である炭化珪素単結晶基板の作製工程の一例を示すフローチャート図である。本発明の実施形態である炭化珪素単結晶基板の作製工程は、表面加工処理工程S10、洗浄処理工程S20、表面検査工程S30および付着粒子低減用表面加工処理工程S15とから概略構成されている。
表面加工処理工程S10は、端面加工処理S11と、粗加工処理S12と、鏡面研磨加工処理S13と、CMP加工表面処理S14と、からなり、洗浄処理工程S20は、粗洗浄処理S21と、形状検査S22と、最終洗浄処理S23と、からなる。また、表面検査工程S30は、光学式表面検査S31と、原子間力顕微鏡(AFM)による表面検査(原子間力式表面検査)S32と、からなる。原子間力式表面検査S32で、合格した炭化珪素単結晶基板を最終品として出荷する。
表面検査工程S30で不合格とされた基板は付着粒子低減用表面加工処理工程S15へ戻し、表面加工処理を行った後、洗浄処理工程S20を行った後、再び表面検査工程S30で表面検査を行う。合格した基板は最終品として出荷し、不合格品は、合格するまで上記のサイクルを続ける。
まず、昇華法などにより形成した炭化珪素単結晶インゴットを切り出して形成した炭化珪素単結晶ウェーハ(炭化珪素単結晶基板)に端面加工処理S11を施す。具体的には、ほぼ直角に切断された前記炭化珪素単結晶基板の表裏の端面縁を、研削等によりR50-200μm程度の円弧形状に加工する。
たとえば、セラミック等で作製された平坦な台(プレート)上に数枚の前記炭化珪素単結晶基板をワックス等により平坦に貼り付け、不織布等を貼り付けた回転する定盤に加工液を供給しながら、該プレートを介して前記炭化珪素単結晶基板の平面を押し付けて回転させ、前記炭化珪素単結晶基板の表面を極めて薄く除去する処理である。これにより、前記炭化珪素単結晶基板の表面ダメージを除去することができ、前記炭化珪素単結晶基板は、鏡面状となる。なお、本表面処理で用いる加工液には、酸化クロム等が用いられる。
たとえば、表面加工処理工程の終了後、プレートを片面加工機に取り付け、純水のみを供給して5分間表面洗浄を実施し、その後、プレートを同機から取り外して水洗した後、炭化珪素単結晶基板をプレートから剥離する。
次に、鏡面状の前記炭化珪素単結晶基板に粗洗浄処理S21を施す。粗洗浄処理S21は、半導体基板の洗浄方法として一般的なRCA洗浄の処理を用いる。RCA洗浄とは、米RCA社が開発した半導体基板の洗浄方法であり、過酸化水素、アルカリおよび酸を加えた薬液を用いて、高温で洗浄する方法である。なお、使用する薬剤及び条件などは、各半導体基板メーカーによって異なる。
まず、炭化珪素単結晶基板に対して光学式表面検査S31を施す。光学式表面検査S31は、従来の表面検査方法であり、主に裸眼あるいは光学顕微鏡を用いた目視やSurfScan(Tencor社製)が用いられ、表面の傷、くもり、及び付着粒子等を検査する。
前記光学式表面検査では、検出手段として光を用いるため、被測定対象の大きさ(高さおよび径)は原理的に光波長以上(100nm:0.1μm以上)である。これにより、高さが100nm以上の付着粒子の大きさ、数および位置を把握することができる。なお、これ以後、高さが100nm以上の付着粒子を第1付着粒子と呼称する。
前記第1付着粒子の密度が1個/cm2以下とされることが好ましい。前記第1付着粒子の密度が1個/cm2以下とされることにより、第1付着粒子に起因するエピタキシャル成長時の異常成長を抑制することができる。
次に、原子間力顕微鏡(AFM)による表面検査(原子間力式表面検査)S32を施す。原子間力式表面検査S32は、原子間力顕微鏡(Atomic Force Microscope:AFM)を用いた表面検査であり、高さ0.05nm~0.5μmまでの粒子を観察することができる。これにより、高さが100nm未満の付着粒子の大きさ、数および位置を把握することができる。なお、これ以後、高さが100nm未満の付着粒子を第2付着粒子と呼称する。
すなわち、第1付着粒子だけでなく第2付着粒子の密度を低減することにより、炭化珪素単結晶ウェーハ基板上の表面清浄度をより向上させ、エピタキシャル成長膜を欠陥なく成膜させることができ、炭化珪素単結晶半導体のプロセス歩留まりを向上させることができる。
なお、Si、GaAs、InPなどを基板として用いた場合には、基板表面上の不純物粒子(付着粒子)は基板の表面に化学的に安定な状態で付着することがなく、従来の洗浄工程を適用することにより、第1付着粒子だけでなく、第2付着粒子も容易に除去される。
付着粒子低減用表面加工処理工程S15は、pH調整剤を含浸させた研磨布とダイヤモンド砥粒からなる研磨剤を用いて表面を研磨処理して第2付着粒子の密度を低減する工程である。
炭化珪素単結晶基板の表面のpHを調整することにより、炭化珪素単結晶基板の表面と付着粒子との間の化学的結合を弱めることができ、化学的に安定して付着した第2付着粒子を除去することが容易になる。その状態で、ダイヤモンド砥粒からなる研磨剤を用いて表面を研磨処理することにより、化学的に安定して付着した第2付着粒子を除去することができる。
たとえば、第1の方法としては、炭化珪素単結晶基板の表面のpHが2以下となるように調整するpH調整剤と、ダイヤモンド砥粒と、を含浸させた研磨布を用いて鏡面研磨する。
また、第2の方法としては、酸化剤及び軟固形剤を含浸させた研磨布を用いて鏡面処理し、pH調整剤を用いてpHが3以下となるように調整し、また珪素、アルミニウム、セリウム、クロムの酸化物の内、一つ又はそれ以上を含有する軟固形材を使用し、酸化剤として、硫酸、塩素、オゾン、次亜塩素酸塩、フッ素イオン、臭素イオンの内、一つ又はそれ以上を含有する水溶液を用いて鏡面研磨する。
これにより、洗浄処理工程を1段階減らすことができ、炭化珪素単結晶基板の作製プロセスを効率化することができる。
以下、本発明を実施例に基づいて具体的に説明する。しかし、本発明はこれらの実施例にのみ限定されるものではない。
図1のフローチャート図に示した炭化珪素単結晶基板の作製工程を用いて、炭化珪素単結晶基板(実施例1サンプル)を作製した。
まず、直径約50mmφの炭化珪素単結晶基板の(0001)8°傾斜基板を用意して、所定の端面加工処理を行った。
次に、上下2枚の平坦な定盤の間に炭化珪素単結晶基板を挟み、研磨剤を供給しながら、2枚の定盤を相互に対向して回転させ、炭化珪素単結晶基板の表裏を削り取って厚さを調整し、平坦度を向上させて、粗加工処理を行った。加工砥粒にはダイヤモンド砥粒を用いた。
次に、上下2枚の平坦な定盤の加工面に不織布等を貼付け、前記2枚の定盤の間に炭化珪素単結晶基板を挟み、より微細な研磨剤を供給しながら、2枚の定盤を相互に対向して回転させ、炭化珪素単結晶基板の表裏を削り取って厚さを調整し、平坦度を向上させて、鏡面研磨加工処理を行った。この際、より微細なダイヤモンド砥粒を用いた。これにより、表面粗さRaが5nm程度の光学的に平坦な鏡面を得た。
なお、この際、仕上げ面はSi極性面とし、表面処理のため低膨張ガラスプレートにC極性面側を貼り付けた片面研磨を行った。加工液としては、市販のコロイダルシリカ水溶液に次亜塩素酸系の酸化剤を添加した。これにより、表面粗さRaが0.05nm以下の加工面を得た。
剥離した炭化珪素単結晶基板の粗洗浄処理をした。粗洗浄処理は、過酸化水素、アルカリおよび酸を加えた薬液を用いて、高温で洗浄するRCA洗浄を用いた。
具体的には、下記の薬剤槽に順次浸漬し、揺動や超音波などが加えた。薬剤槽は、アセトン槽、メタノール槽、純水槽、SPM槽(硫酸、過酸化水素混合液)、純水槽、SC1槽(アンモニア及び過酸化水素の水溶混合液)、純水槽、フッ酸槽、純水槽、SC2槽(塩酸及び過酸化水素の水溶混合液)、純水槽、フッ酸槽、純水槽、IPA槽とした。IPA槽の浸漬処理後、IPA槽から引き上げた状態で、IPAの蒸気乾燥をして、乾燥処理した。
次に、フラットネステスター及び光学的マイクロメーターによる形状検査を実施して、平坦度が許容範囲内であることを確認した後、粗洗浄処理と同様にしてRCA洗浄の最終洗浄処理をした。
まず、最終洗浄処理した炭化珪素単結晶基板の暗視野目視検査及びSurfScan(Tencor社製)による光学式表面検査を行った。炭化珪素単結晶基板には表面の傷、くもりは観察されなかった。
図3は、原子間力式表面検査で得られた炭化珪素単結晶基板の表面の写真である。図3に示す測定領域に0.5以上100nm未満の高さの付着粒子は1つも観測されなかった。このようにして、炭化珪素単結晶基板の表面全面をAFMで測定することにより、高さ0.5以上100nm未満の高さの付着粒子の密度が100個/cm2であることが分かった。なお、炭化珪素単結晶基板の表面粗さRaは0.1nm以下であった。
表面加工処理工程終了後、プレートを片面加工機に取り付け、純水のみを供給して実施した表面洗浄の時間を1分間としたほかは実施例1と同様にして、炭化珪素単結晶基板(実施例2サンプル)の作製を行った。
炭化珪素単結晶基板の暗視野目視検査及びSurfScan(Tencor社製)による光学式表面検査では、炭化珪素単結晶基板には表面の傷、くもりは観察されず、0.1μm以上の付着粒子等は全面で1個(1個/cm2)であった。
次に、炭化珪素単結晶基板の表面全面をAFMで測定することにより、高さ0.5以上100nm未満の高さの付着粒子の密度が1500個/cm2であることが分かった。
図4のフローチャート図に示した従来の炭化珪素単結晶基板の作製工程を用いて、炭化珪素単結晶基板(比較例1サンプル)を製造した。
まず、実施例1と同様にして表面加工処理工程を行った後、プレートを加工機から取り外し、水洗により加工液を除去した後、炭化珪素単結晶基板をプレートから剥離した。
次に、実施例1と同様にして、粗洗浄処理、形状検査、最終洗浄処理とからなる洗浄処理工程を行った後、表面検査工程を行った。
次に、炭化珪素単結晶基板の表面全面をAFMで測定することにより、高さ0.5以上100nm未満の高さの付着粒子の密度が1x104個/cm2であることが分かった。
Claims (9)
- 基板の一面に付着した高さが100nm以上の第1付着粒子の密度が1個/cm2以下とされ、かつ、前記基板の一面に付着した高さが100nm未満の第2付着粒子の密度が1500個/cm2以下とされていることを特徴とする炭化珪素単結晶基板。
- 前記第2付着粒子の密度が100個/cm2以下とされていることを特徴とする請求項1に記載の炭化珪素単結晶基板。
- pH調整剤を含浸させた研磨布とダイヤモンド砥粒からなる研磨剤を用いて表面を研磨処理する付着粒子低減用表面加工処理工程を行って形成されてなることを特徴とする請求項1に記載の炭化珪素単結晶基板。
- 前記付着粒子低減用表面加工処理工程の前に、原子間力顕微鏡(AFM)による表面検査を行って前記第2付着粒子の密度を測定することを特徴とする請求項3に記載の炭化珪素単結晶基板。
- 前記pH調整剤が前記炭化珪素単結晶基板の表面のpHを3以下とすることを特徴とする請求項3に記載の炭化珪素単結晶基板。
- 前記pH調整剤が前記炭化珪素単結晶基板の表面のpHを2以下とすることを特徴とする請求項3に記載の炭化珪素単結晶基板。
- 前記研磨布に更に酸化剤または/および軟固形剤を含浸させることを特徴とする請求項3に記載の炭化珪素単結晶基板。
- 前記軟固形剤が珪素、アルミニウム、セリウムまたはクロムのいずれかの金属酸化物を一以上含有することを特徴とする請求項7に記載の炭化珪素単結晶基板。
- 前記酸化剤が硫酸、塩素、オゾン、次亜塩素酸塩、フッ素イオン、臭素イオンのいずれかを一以上含有する水溶液であることを特徴とする請求項7に記載の炭化珪素単結晶基板。
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JP5803786B2 (ja) * | 2012-04-02 | 2015-11-04 | 住友電気工業株式会社 | 炭化珪素基板、半導体装置およびこれらの製造方法 |
US11302669B2 (en) * | 2015-10-15 | 2022-04-12 | Skyworks Solutions, Inc. | Wire bond cleaning method and wire bonding recovery process |
CN105280765B (zh) * | 2015-11-18 | 2018-01-09 | 海迪科(南通)光电科技有限公司 | 一种基于图形化蓝宝石衬底的led芯片去腊工艺 |
JP6996438B2 (ja) * | 2018-07-11 | 2022-01-17 | 株式会社Sumco | 半導体ウェーハの洗浄方法、および該洗浄方法を用いた半導体ウェーハの製造方法 |
JP6491784B1 (ja) * | 2018-08-03 | 2019-03-27 | 株式会社日立パワーソリューションズ | 単結晶炭化ケイ素基板、単結晶炭化ケイ素基板の製造方法、および半導体レーザ |
JP2020202289A (ja) * | 2019-06-10 | 2020-12-17 | 昭和電工株式会社 | SiCエピタキシャルウェハの製造方法 |
JP2021077757A (ja) * | 2019-11-08 | 2021-05-20 | 株式会社ディスコ | SiC基板の再生方法 |
KR102229588B1 (ko) | 2020-05-29 | 2021-03-17 | 에스케이씨 주식회사 | 웨이퍼의 제조방법, 에피택셜 웨이퍼의 제조방법, 이에 따라 제조된 웨이퍼 및 에피택셜 웨이퍼 |
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US20130224954A1 (en) | 2013-08-29 |
KR20110057181A (ko) | 2011-05-31 |
CN102165563A (zh) | 2011-08-24 |
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CN102165563B (zh) | 2013-06-05 |
EP2330615A4 (en) | 2014-04-16 |
KR101292884B1 (ko) | 2013-08-02 |
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