[go: up one dir, main page]

US20170321345A1 - Large Diameter Silicon Carbide Single Crystals and Apparatus and Method of Manufacture Thereof - Google Patents

Large Diameter Silicon Carbide Single Crystals and Apparatus and Method of Manufacture Thereof Download PDF

Info

Publication number
US20170321345A1
US20170321345A1 US15/584,583 US201715584583A US2017321345A1 US 20170321345 A1 US20170321345 A1 US 20170321345A1 US 201715584583 A US201715584583 A US 201715584583A US 2017321345 A1 US2017321345 A1 US 2017321345A1
Authority
US
United States
Prior art keywords
growth
crucible
sic
single crystal
insulation
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.)
Abandoned
Application number
US15/584,583
Other languages
English (en)
Inventor
Xueping Xu
Ilya Zwieback
Avinash K. Gupta
Varatharajan Rengarajan
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.)
Ii Vi Optical Systems Inc
Photop Technologies Inc
Finisar Corp
Marlow Industries Inc
M Cubed Technologies Inc
LightSmyth Technologies Inc
Optium Corp
Coadna Photonics Inc
Epiworks Inc
Kailight Photonics Inc
II VI Delaware Inc
II VI Optoelectronic Devices Inc
II VI Photonics US LLC
Coherent Corp
Original Assignee
II VI Inc
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 II VI Inc filed Critical II VI Inc
Priority to US15/584,583 priority Critical patent/US20170321345A1/en
Priority to JP2017092554A priority patent/JP6373443B2/ja
Publication of US20170321345A1 publication Critical patent/US20170321345A1/en
Assigned to II-VI INCORPORATED reassignment II-VI INCORPORATED ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: GUPTA, AVINASH K., RENGARAJAN, VARATHARAJAN, XU, XUEPING, ZWIEBACK, ILYA
Priority to US16/458,385 priority patent/US11035054B2/en
Assigned to BANK OF AMERICA, N.A., AS ADMINISTRATIVE AGENT reassignment BANK OF AMERICA, N.A., AS ADMINISTRATIVE AGENT NOTICE OF GRANT OF SECURITY INTEREST IN PATENTS Assignors: COADNA PHOTONICS, INC., EPIWORKS, INC., FINISAR CORPORATION, II-VI DELAWARE, INC., II-VI INCORPORATED, II-VI OPTICAL SYSTEMS, INC., II-VI OPTOELECTRONIC DEVICES, INC., II-VI PHOTONICS (US), INC., KAILIGHT PHOTONICS, INC., LIGHTSMYTH TECHNOLOGIES, INC., M CUBED TECHNOLOGIES, INC., MARLOW INDUSTRIES, INC., OPTIUM CORPORATION, PHOTOP TECHNOLOGIES, INC.
Priority to US17/249,597 priority patent/US11905618B2/en
Assigned to LIGHTSMYTH TECHNOLOGIES, INC., PHOTOP TECHNOLOGIES, INC., FINISAR CORPORATION, II-VI PHOTONICS (US), INC., II-VI DELAWARE, INC., MARLOW INDUSTRIES, INC., M CUBED TECHNOLOGIES, INC., II-VI OPTICAL SYSTEMS, INC., II-VI INCORPORATED, OPTIUM CORPORATION, II-VI OPTOELECTRONIC DEVICES, INC., KAILIGHT PHOTONICS, INC., EPIWORKS, INC., COADNA PHOTONICS, INC. reassignment LIGHTSMYTH TECHNOLOGIES, INC. PATENT RELEASE AND REASSIGNMENT Assignors: BANK OF AMERICA, N.A., AS ADMINISTRATIVE AGENT
Priority to US18/415,291 priority patent/US20240150931A1/en
Abandoned legal-status Critical Current

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
    • C30B23/00—Single-crystal growth by condensing evaporated or sublimed materials
    • C30B23/02—Epitaxial-layer growth
    • C30B23/06—Heating of the deposition chamber, the substrate or the materials to be evaporated
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
    • C30B25/02—Epitaxial-layer growth
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/02—Silicon
    • C01B33/021—Preparation
    • C01B33/023—Preparation by reduction of silica or free silica-containing material
    • C01B33/025—Preparation by reduction of silica or free silica-containing material with carbon or a solid carbonaceous material, i.e. carbo-thermal process
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T117/00—Single-crystal, oriented-crystal, and epitaxy growth processes; non-coating apparatus therefor

Definitions

  • SiC silicon carbide
  • SiC single crystals find their use in a variety of semiconductor, electronic, and optoelectronic devices where SiC wafers serve as substrates for the growth of epitaxial layers of SiC or GaN.
  • the epilayers are then fabricated into devices, such as power switching devices, RF/microwave devices and LEDs.
  • SiC-based and GaN-based devices can operate at much higher temperature, power level, frequency—all combined with improved efficiency.
  • SiC-based and GaN-based devices Wide-spread application of SiC-based and GaN-based devices is hampered by the high cost the SiC substrate, which is a major contributor to the overall device cost.
  • the largest 4H-SiC and 6H-SiC substrates available commercially are of 100 mm and 150 mm in diameter, while development of 200 mm SiC substrates has been announced.
  • Implementation of large-size SiC substrates, such as of 200 mm, 250 mm or 300 mm in diameter in the device technology can substantially reduce the cost of SiC- and GaN-based devices.
  • Crystal defects in the SiC substrate are harmful to the device performance, especially in the SiC-based power switching devices formed on N-type 4H-SiC substrates. It is known that threading dislocations cause charge leakage and device degradation, while basal plane dislocations and stacking faults can cause terminal device failure. Stress and strain in the SiC substrate are negative factors in device processing.
  • FIG. 1 A sectional view of a conventional PVT growth apparatus is shown schematically in FIG. 1 , wherein a graphite growth crucible 1 charged with a SiC source material 2 and a single crystal SiC seed 3 in spaced relation is placed in a growth chamber 20 .
  • a heating means 4 for heating the interior of crucible 1 to a sublimation growth temperature, e.g., between 2000° C. and 2400° C., can be provided about the exterior of chamber 20, which can be water-cooled and formed from fused silica.
  • heating means 4 can be an exterior RF heating coil.
  • heating means in the form of a resistance heater inside chamber 20 is envisioned.
  • heating means 4 will be described as being an RF heating coil. However, this is not to be construed in a limiting sense.
  • Crucible 1 is surrounded by thermal insulation 5 inside of chamber 20 .
  • a top window 5 a having a relatively small diameter is provided in thermal insulation 5 .
  • This window 5 a is provided for heat dissipation from the backside of SiC seed 3 attached to a top or lid 22 of growth crucible 1 .
  • Window 5 a can also serve for measuring the temperature of the crucible top using an optical pyrometer via a sealed viewing port 30 in top or lid 22 of chamber 20 .
  • chamber 20 and, hence, growth crucible 1 are evacuated via a vacuum pump and are filled to a desired pressure with a suitable process gas or gases, e.g., argon, nitrogen, boron, supplied through an inlet 36 .
  • a suitable process gas or gases e.g., argon, nitrogen, boron
  • the gas pressure inside of chamber 20 and, hence, growth crucible 1 can be controlled to a pressure suitable for growth of SiC single crystal 6 on single crystal SiC seed 3 .
  • this pressure can be between 5 and 300 Torr.
  • a window 5 b can be provided in thermal insulation adjacent a bottom of growth crucible 1 for temperature measurement of crucible 1 using an optical pyrometer via a sealed viewing port 30 in a bottom 24 of crucible 20 .
  • crucible 1 is heated by heating means 4 to a temperature between 2000° C. and 2400° C. sufficient to vaporize the SiC source material 2 and fill the crucible material with vapor species 7 of SiC 2, Si 2 C and Si in the presence of a suitable pressure of the process gas within chamber 20 and, hence, growth crucible 1 .
  • growth crucible 1 is formed of porous graphite, process gas introduced into chamber 20 appears almost immediately in the interior of growth crucible 1 . Similarly, a vacuum applied to chamber 20 appears almost immediately in the interior of growth crucible 1 .
  • An axial temperature gradient is introduced in crucible 1 by properly positioning heating means 4 with respect to crucible 1 such that the temperature of SiC source material 2 is higher than that of SiC seed 3 .
  • this temperature gradient can be between 30° C. and 150° C. However, this is not to be construed in a limiting sense.
  • the vapor species 7 migrate toward SiC seed 3 , as illustrated schematically by arrow 7 , and condense on SiC seed 3 causing growth of a SiC single crystal 6 on SiC seed 3 .
  • the pattern of heat transport in the PVT growth apparatus is shown schematically in FIG. 1 by arrows 8 and 9 .
  • the heat absorbed by crucible 1 from heating means 4 is transported into the crucible interior by horizontal heat fluxes 8 .
  • Heat escapes crucible 1 via the top of crucible 1 and top window 5 a in the form of vertical heat flux 9 .
  • curved isotherms 10 emerge in the crucible 1 and in the growing SiC single crystal 6 .
  • U.S. Pat. No. 6,800,136 discloses a PVT growth apparatus and method, wherein harmful radial gradients in SiC sublimation growth can be reduced.
  • the apparatus utilizes two flat heaters disposed below and above the exterior of the crucible. Disadvantages of this arrangement include: (i) in the case of RF heating, poor coupling of the flat RF coils to the crucible; and (ii) in the case of resistive heating, concave radial temperature gradients in the growing crystal lead to a concave growth interface.
  • U.S. Pat. No. 6,800,136 is incorporated herein by reference.
  • U.S. Pat. No. 8,741,413 discloses a SiC sublimation growth apparatus and method, wherein the flux of SiC bearing vapors is restricted to the central area of the growing crystal. SiC boules grown using this arrangement suffer from the growth interface being too convex.
  • U.S. Pat. No. 8,741,413 is incorporated herein by reference.
  • U.S. Pat. No. 9,228,274 discloses another SiC sublimation growth apparatus and method, wherein the heating arrangement includes a growth crucible positioned between two resistive heaters, a top heater and a bottom heater.
  • the heaters are disposed coaxially with the crucible: the top, ring-shaped heater is disposed above the crucible, while the bottom, cup-shaped heater is disposed below and around the crucible.
  • This arrangement has the following disadvantage: during growth, the SiC source vaporizes predominantly from the hotter areas located at the crucible walls, thus supplying the vapor mostly to the periphery of the growing SiC crystal. This leads to a concave growth interface, especially when the boule diameter is large.
  • U.S. Pat. No. 9,228,274 is incorporated herein by reference.
  • a large size seed can be produced by intergrowth of smaller-size, tiled seed crystals, as disclosed in U.S. Pat. No. 6,805,745, which is incorporated herein by reference.
  • a growth apparatus that produces near-zero radial temperature gradients and a flat growth interface in the growing SiC boule, yielding high-quality SiC single crystals suitable for the fabrication of high-quality SiC substrates or wafers of standard diameters of 200 mm, 250 mm, and 300 mm.
  • Disclosed herein are large-diameter, high crystal quality SiC single crystal boules of 4H and 6H polytype grown by sublimation, and large-diameter, high-quality SiC single crystal substrates, N-type and semi-insulating fabricated from said boules, including substrates of standard diameters of 200 mm, 250 mm, and 300 mm.
  • FIG. 1 is a sectional view of a conventional view (prior art) example PVT growth apparatus
  • FIG. 2 is a sectional view of an example large-diameter PVT growth apparatus in accordance with the principles described herein;
  • FIGS. 3A-3D are examples of the heating means (e.g., resistive heaters) that can be used in the example PVT growth apparatus shown in FIG. 2 , wherein each heating means has a different conductive pattern for connection to delta and star three-phase electrical power ( FIGS. 3A-3B ) and single-phase electrical power ( FIGS. 3C-3D );
  • each heating means has a different conductive pattern for connection to delta and star three-phase electrical power ( FIGS. 3A-3B ) and single-phase electrical power ( FIGS. 3C-3D );
  • FIGS. 4A-4E are different configuration insulation inserts that can be used with the PVT growth apparatus shown in FIG. 2 ;
  • FIG. 5 is a flow diagram of a method for producing by diameter expansion a SiC single crystal boule from which a SiC single crystal wafer can be sliced and used as the single crystal SiC seed in the PVT growth apparatus of FIG. 2 ;
  • FIG. 6 is a photograph of an N-type 4H-SiC boule grown in accordance with Example 1 growth described herein;
  • FIG. 7 is a cross-polarizer image of a wafer extracted from the boule shown in FIG. 6 ;
  • FIG. 8A is a graph of lattice curvature versus distance along the wafer diameter of the wafer shown in FIG. 7 ;
  • FIG. 8B is a graph of FWHM versus distance along the wafer diameter of the wafer shown in FIG. 7 ;
  • FIG. 9 is a micropipe density map of the wafer shown in FIG. 7 ;
  • FIGS. 10A-10C are maps of overall dislocation density, screw dislocation density, and basal plane dislocation density, respectively, measured on the wafer shown in FIG. 7 ;
  • FIG. 11 is a photograph of a vanadium doped, semi-insulating 4H-SiC boule grown in accordance with Example 2 growth run described herein.
  • FIG. 2 A sectional view of an example large-diameter PVT growth apparatus for the growth of large-diameter SiC single crystals is shown schematically in FIG. 2 .
  • the PVT growth apparatus of FIG. 2 includes a graphite growth crucible 1 , thermal insulation 12 (including cylindrical side insulation 12 a , top insulation 12 b , and bottom insulation 12 c ) and a heating means in the form of a single flat resistive heater 40 positioned between a bottom 26 of growth crucible 1 and bottom insulation 12 c .
  • thermal insulation 5 can be made of lightweight fiberous graphite, such as graphite felt or foam.
  • chamber 20 can be optionally water-cooled.
  • chamber 20 can be formed of any suitable and/or desirable material capable of withstanding the heat produced by resistive heater 40 during growth of growing SiC single crystal 6 on single crystal SiC seed 3 .
  • chamber 20 can be formed of fused silica or a suitable metal or a metal alloy, such as stainless steel. However, this is not to be construed in a limiting sense since it is envisioned that chamber 20 can be formed of any suitable and/or desirable material.
  • resistive heater 40 can be made of dense graphite.
  • the graphite can be iso-molded or extruded.
  • Resistive heater 40 can be shaped as a flat disc and can be positioned under growth crucible 1 as shown in FIG. 2 .
  • electric configurations of resistive heater 40 can include three-phase “Delta” ( FIG. 3A ), three phase “Star” ( FIG. 3B ), or single phase ( FIGS. 3C-3D ).
  • the patterns of resistive heaters 40 shown in FIGS. 3A-3D are not to be construed in a limiting sense.
  • growth crucible 1 In preparation for growth, growth crucible 1 , charged with SiC source material 2 and a single crystal SiC seed 3 in spaced relation, can be placed in a growth chamber 20 , wherein the resistive heater 40 can be disposed below the crucible bottom 26 , as shown in FIG. 2 .
  • Growth crucible 1 can be positioned inside chamber 20 which can be optionally water-cooled and optionally made from fused silica, a metal, or a metal alloy. However, this is not to be construed in a limiting sense.
  • Thermal insulation 12 can surround crucible 1 and can be positioned between crucible 1 and chamber 20 .
  • the top window 5 a in the insulation 5 in FIG. 1 can be replaced in FIG. 2 with a thermal insulation insert 12 d positioned in an opening 14 of thermal insulation 12 b that extends across at least a portion of the exterior top of crucible 1 , whereupon the thermal insulation above the top or lid of growth crucible 1 includes top insulation 12 b and thermal insulation insert 12 d .
  • the thickness and shape of insulation insert 12 d are discussed below.
  • Small-diameter windows 16 and 18 can be provided in the bottom insulation piece 12 c and in heater 40 , respectively. These windows serve for temperature measurement, via an optical pyrometer, via a sealed viewing port 34 in the bottom 26 of crucible 1 .
  • crucible 1 can be heated by resistive heater 40 to SiC sublimation temperature, e.g., between 2000° C. and 2400° C., to vaporize SiC source material 2 and fill the crucible 1 with C and Si-bearing vapor species 7 in the presence of a suitable gas pressure within chamber 20 and, hence, within growth crucible 1 .
  • SiC sublimation temperature e.g., between 2000° C. and 2400° C.
  • the pattern of heat transport in PVT growth apparatus shown in FIG. 2 differs from that of the example PVT growth apparatus shown in FIG. 1 .
  • Heat transport in the PVT growth apparatus of FIG. 2 is vertical, as shown schematically by arrows 8 and 9 in FIG. 2 .
  • Heat from resistive heater 40 which is disposed below the bottom 26 of growth crucible 1 , is transported into the interior of crucible 1 by the axial heat fluxes shown by arrows 8 .
  • Heat escapes from a top or lid 22 of growth crucible 1 in the form of the axial heat fluxes shown by arrows 9 , which diffuse across thermal insulation insert 12 d .
  • flat isotherms 10 emerge in the interior of growth crucible 1 and in the growing SiC single crystal 6 .
  • Insulation insert 12 d can be made of fibrous graphite insulation board.
  • a value for the thickness t of insulation insert 12 d can be determined from SiC growth experiments. However, an approximate value oft (in mm) can be calculated using the following equation:
  • Eq. 1 ⁇ is the thermal conductivity of the insulation insert 12 d (W/mK)
  • ⁇ T is the temperature difference across the insulation insert 12 d (° K)
  • A is the area (m 2 ) of the insulation insert 12 d
  • Q is the heat flux across the insulation insert 12 d (kW).
  • Example dimensions of the flat, disc-shaped insulation insert 12 d can include: thickness desirably between 20 and 50 mm, or more desirably between 25 and 45 mm; and diameter between 90% and 120% of the diameter of the single crystal SiC seed 3 .
  • Isotherms 10 and radial temperature gradients in growth crucible 1 can be further controlled by using non-flat, shaped insulation inserts 12 d 1 - 12 d 4 .
  • Example configurations of insulation inserts 12 d - 12 d 4 are shown in FIGS. 4A-4E .
  • insulation insert 12 d ( FIG. 4A ) can be a flat insert with parallel top and bottom surfaces.
  • Insulation inserts 12 d 1 and 12 d 2 FIGS. 4B-4C ) can have planar top surfaces and bottom surfaces (which, in use, faces growth crucible 1 ) with sloped edges.
  • Insulation inserts 12 d 3 and 12 d 4 can have planar top surfaces and bottom surfaces (which, in use, faces growth crucible 1 ) with rounded edges. Inserts 12 d 1 and 12 d 3 ( FIGS. 4B-4D ) can have concave shapes. Inserts 12 d 2 and 12 d 4 ( FIGS. 4C and 4E ) can have convex shapes. Inserts 12 d 1 and 12 d 3 can have a flat central portion and the edge area concave or sloped towards growth crucible 1 . These inserts 12 d 1 and 12 d 3 can be used when the growth interface of SiC single crystal 6 is concave and the crystal attaches to a growth guide 11 of crucible 1 .
  • Insulation inserts 12 d 2 and 12 d 4 can have a flat central portion and the edge area convex sloped away from growth crucible 1 . These inserts 12 d 2 and 12 d 4 can be used when the growth interface of SiC single crystal 6 is convex.
  • the radius or curvature or the angle of slope of the concave ( 12 d 1 and 12 d 3 ) or convex ( 12 d 2 and 12 d 4 ) edge areas, and/or where the flat central portion of insulation insert(s) 12 d 1 - 12 d 4 ends and where said radius of curvature or slope begins can be selected or tuned as necessary to cause flat (or substantially flat) isotherms 10 to be present at the growth interface of growing SiC single crystal 6 , inside of the growing SiC single crystal 6 , and within growth crucible 1 .
  • the aspect ratio of the growth crucible 1 defined as a ratio of the outside diameter (OD) of crucible 1 to the height of crucible 1 , can be greater than one, i.e., the crucible OD is larger than its height. It has been observed that increasing the crucible OD helps further reduce undesirable radial temperature gradients in the central areas of crucible 1 .
  • the aspect ratio of growth crucible 1 can desirably be between 1 and 3, or more desirably between 1.5 and 2.5.
  • the aspect ratio of growth crucible 1 can desirably be between 1.5 and 4, or more desirably between 2 and 3.
  • top or lid 22 of growth chamber 20 is colored black, whereupon said black coloring enables top 22 to absorb heat flux coming into contact therewith while avoiding or reducing reflection of said heat flux back into the interior of chamber 20 .
  • the interior surface of top 22 can be colored black in any suitable or desirable manner such as, for example, a high temperature black paint that is compatible with the material forming top or lid 22 . However, this is not to be construed in a limiting sense.
  • top or lid 22 of chamber 20 By coloring its interior facing surface black, top or lid 22 of chamber 20 more closely approximates a black body (known in classical physics) that absorbs radiation that falls on its surface. Of course, an ideal black body that absorbs all radiation does not exist. However, by coloring at least the interior surface of top or lid 22 of chamber 20 black, or forming top 22 of a material that is black in color, the reflection of heat flux from top 22 back into chamber 20 can be reduced or avoided enabling at least some control of heat flux being reflected by the interior facing surface of top or lid 22 back into chamber 20 .
  • a black body known in classical physics
  • top or lid 22 While not ideal, the black colored interior facing surface of top or lid 22 has been observed to be advantageous in the formation of flat (or substantially flat) isotherms 10 within growth crucible 1 and, more particularly, at the growth interface of growing SiC single crystal 6 , and inside of the growing SiC single crystal 6 .
  • a substantially flat isotherm (as determined by finite element analysis) is considered to be one that corresponds to a radial temperature variation in the growth crucible 1 of less than 10° C. between a central axis 42 of the growth crucible 1 and the outside diameter of the SiC single crystal 6 growing on SiC seed 3 .
  • this is not to be construed in a limiting sense.
  • Example 1 Run GQ0090: Growth of High Crystal Quality 200 mm Diameter N-Type 4H-SiC Boule
  • a high quality 4H-SiC single crystal seed 3 wafer was prepared having a diameter of 225 mm and oriented 4 degrees off-axis.
  • This single crystal SiC seed 3 wafer was sliced from a large-diameter 4H SiC boule produced by diameter expansion in accordance with the teaching of US 2012/0285370 and/or U.S. Pat. No. 8,313,720.
  • Expansion of the SiC boule diameter was accomplished through a number of sequential crystal growth runs, according to the flowchart shown in FIG. 5 .
  • Diameter expansion starts with selection of a quality single crystal SiC seed 3 of smaller diameter. This seed can be used in a PVT growth process tuned to produce defect-free or substantially defect-free diameter expansion.
  • the thus grown SiC single crystal 6 boule can be sliced into wafers which are larger in diameter than the initial SiC seed 3 .
  • the wafers can be thoroughly characterized, and only best quality wafers can be used as seeds 3 in the next growth run (expansion round).
  • the growth process in each run can be tuned, for example, to optimize SiC single crystal 6 growth for each round of expansion.
  • the PVT growth apparatus shown in FIG. 2 was used in the growth run of this Example 1.
  • the graphite growth crucible 1 of this PVT growth apparatus had a 250 mm OD.
  • the growth crucible 1 was loaded with SiC source grain material 2 disposed at the crucible bottom.
  • the aforementioned 4H-SiC single crystal seed 3 wafer of 225 mm in diameter was disposed at the interior top or lid 22 of growth crucible 1 .
  • the three-phase flat serpentine heater 40 shown schematically in FIG. 3A was positioned under the bottom 26 of crucible 1 .
  • Insulation insert 12 d was made of a rigid insulation board.
  • the insulation insert 12 d dimensions were 220 mm diameter and 25 mm thick.
  • temperatures and pressures typical for the prior art PVT growth were used.
  • gaseous nitrogen was added to the growth atmosphere as the process gas.
  • the growth run of this Example 1 yielded the 4H-SiC boule shown in FIG. 6 .
  • the boule had a flat growth interface; accordingly, a small c-facet was visible at the very edge of the boule.
  • the flat growth interface was the consequence of flat isotherms and a sign of low crystal stress.
  • the as-grown boule of Example 1 was processed into 200 mm diameter wafers. A cross-polarizer image taken of one these wafers is shown in FIG. 7 . The image shows neither local nor global crystal stress.
  • Wafers sliced from the as-grown boule of Example 1 were polished and characterized using X-ray rocking curves. The wafers were scanned in two orthogonal directions: parallel to the ⁇ 1-210> crystallographic direction and parallel to the ⁇ 10-10> direction. The results obtained from one of these wafers are shown in FIGS. 8A-8B . As can be seen, the lattice curvature ( FIG. 8A ) in this wafer is below 0.1°, while FWHM ( FIG. 8B ) across the entire wafer area does not exceed 25 arc-seconds. This testifies to the excellent crystal quality of this as-grown SiC wafer.
  • FIG. 9 is a micropipe density map measured on one of the 200 mm wafers sliced from the 4H-SiC boule of Example 1. As can be seen, the wafer is practically micropipe free, with only a few micropipes visible near the wafer edge. The wafer-average micropipe density (MPD) in this wafer was measured to be 0.09 cm ⁇ 2 , thus demonstrating very high crystal quality.
  • MPD micropipe density
  • Dislocation density maps measured on one of the 200 mm wafers sliced from the 4H-SiC boule of Example 1 are shown in FIGS. 10A-10C .
  • Dislocation etch pits were revealed by etching the wafer in molten KOH.
  • the wafer had a total dislocation density of 2800 cm ⁇ 2 ( FIG. 10A ), threading screw dislocation (TSD) density of 620 cm ⁇ 2 ( FIG. 10B ), and basal plane dislocation (BPD) density of 170 cm ⁇ 2 ( FIG. 10C ). All these results point to excellent crystal quality.
  • Example 2 Run GP0105: Growth of High Crystal Quality 200 mm Diameter Vanadium-Doped Semi-Insulating 4H-SiC Boule
  • a high quality 4H-SiC single crystal seed 3 wafer of 210 mm in diameter was prepared.
  • This SiC seed 3 wafer was sliced from a larger diameter 4H-SiC boule grown by the process of diameter expansion discussed above.
  • the SiC seed 3 wafer was sliced on-axis, that is, with its faces parallel to the basal (0001) plane.
  • Example 2 Growth in this Example 2 was carried out in a PVT growth apparatus similar to that shown in FIG. 2 .
  • vanadium doping was employed combined with precise control over the presence of background impurities of nitrogen and boron.
  • Vanadium compensation of silicon carbide was in accordance with the teachings of U.S. Pat No. 7,608,524 and U.S. Pat. No. 8,216,369.
  • Example 2 yielded a 4H-SiC boule of 209 mm in diameter shown in FIG. 11 .
  • the as-grown boule was fabricated into a plurality of 200 mm wafers, which were characterized.
  • the characterization included evaluation of electrical properties and crystal quality.
  • the results showed that the produced wafers were of Nu-type with their room-temperature resistivity above 1 ⁇ 10 12 Ohm-cm and the activation energy of resistivity of about 1 eV.
  • Etching of a wafer sliced from the boule of this Example 2 in molten KOH revealed a wafer-averaged micropipe density of 0.1 cm ⁇ 2 .
  • Scanning of a polished wafer with X-ray rocking curves showed a lattice curvature of below 0.1° and a full width at half maximum (FWHM) of the X-ray reflection below 25 arc-seconds.
  • a PVT growth apparatus for PVT growing an SiC single crystal comprising growth chamber 20 .
  • Growth crucible 1 is positioned in the growth chamber 20 .
  • the growth crucible is configured to be charged with a SiC source material 2 at a bottom 26 of the growth crucible 1 and a single crystal SiC seed 3 at a top or lid 28 of the growth crucible 1 with the SiC source material and the single crystal SiC seed in spaced relation.
  • Thermal insulation 12 surrounds the growth crucible 1 inside of the growth chamber 20 .
  • the thermal insulation 12 includes a side insulation piece 12 a between a side 30 of the growth crucible 1 and a side 25 of the growth chamber 20 , a bottom insulation piece 12 c between the bottom 26 of the growth crucible 1 and a bottom 24 of the growth chamber 20 , a top insulation piece 12 c between the top 28 of the growth crucible 1 and a top 22 of the growth chamber 20 .
  • the thermal insulation 12 also includes an insulation insert 12 d positioned in an opening 32 in the top insulation piece 12 b .
  • the insulation insert 12 d has a thickness between 20 mm and 50 mm and a largest dimension between 90% and 120% of a largest dimension of the single crystal SiC seed 3 .
  • a geometry of the insulation insert can be tuned to control heat flux in the SiC single crystal that grows on the single crystal SiC seed in use of the PVT growth apparatus.
  • a heater 40 is positioned between the bottom 26 of the growth crucible 1 and the bottom insulation piece 12 c.
  • the side 30 of the growth crucible 1 have a cylindrical shape about a central axis 42 .
  • At least an interior facing surface of the top 22 of the growth chamber 20 that faces the insulation insert 12 d can be black in color.
  • the growth chamber 20 is made from a metal or metal alloy, such as stainless steel.
  • At least the exterior facing surface of the top 22 of the growth chamber 20 that faces away from the insulation insert 12 d can also be black in color.
  • a growth guide 11 can depend from the top 28 of the growth crucible 1 toward the bottom 26 of the growth crucible 1 and terminate above a top level of the SiC source material 2 .
  • the growth guide 11 can be spaced from an interior of the side 30 of the growth crucible 1 .
  • the side, top, and bottom insulation pieces 12 a , 12 b , 12 c can each have a thickness greater than or equal to the thickness of the insulation insert 12 d .
  • the side, top, and bottom insulation pieces 12 a , 12 b , and 12 c can each have a thickness that is at least two times the thickness of the insulation insert 12 d.
  • the heater 40 can comprise a flat resistance heater.
  • the heater 40 can have a largest dimension greater than a largest dimension of the bottom 26 of the growth crucible 1 .
  • no part of the heater 40 resides in a space between the side 30 of the growth crucible 1 and the side 25 of the growth chamber 20 occupied by the side insulation piece 12 a.
  • the heater 40 can reside exclusively between the bottom 26 of the growth crucible 1 and the bottom insulation piece 12 c.
  • a ratio of an outside diameter of the growth crucible 1 over a height of the growth crucible 1 can be between 1 and 3 or between 1.5 and 4.
  • a PVT growth apparatus for PVT growing an SiC single crystal comprising a growth crucible 1 having a side 30 , a top 28 , and a bottom 26 , and an aspect ratio of an outside diameter over a height between 1 and 4.
  • the top 28 of the growth crucible 1 is configured to support a single crystal SiC seed 3 in an interior of the growth crucible 1 .
  • Insulation 12 surrounds an exterior of the growth crucible 1 .
  • the insulation 12 includes side, top, and bottom insulation pieces 12 a , 12 b , 12 c positioned adjacent the respective side, top, and bottom 30 , 28 , 26 of the growth crucible 1 .
  • the insulation 12 further includes an insulation insert 12 d positioned in an opening 32 in the top insulation piece 12 b .
  • the insulation insert 12 d has a thickness less than a thickness of any one or more of the side, top, and bottom insulation pieces 12 a , 12 b , 12 c .
  • a geometry of the insulation insert can be tuned to control heat flux in the SiC single crystal that grows on the single crystal SiC seed in use of the PVT growth apparatus.
  • a heater 40 is positioned exclusively between a bottom 26 of the growth crucible 1 and the bottom insulation piece 12 c.
  • the insulation insert 12 d can have a thickness between 20 mm and 50 mm and a diameter between 90% and 120% of a diameter of a the single crystal SiC seed 3 .
  • the PVT growth apparatus can further include a growth chamber 20 in which the growth crucible 1 , insulation 12 , and heater 40 are positioned.
  • the growth chamber 20 can include a top 22 in spaced relation to the top 28 of the growth crucible 1 . At least an interior facing surface of the top 22 of the growth chamber 20 can be black in color.
  • the PVT growth apparatus can further include at least one of the following: a window 5 b in the bottom insulation piece 12 c ; and a window 5 c in the heater 40 .
  • step (b) of the method can include purely axial heat fluxes 8 , 9 passing through the bottom 26 and the top 28 of the growth crucible 1 forming a flat isotherm at least at a growth interface of the growing SiC single crystal 6 on the single crystal SiC seed 3 .
  • the growth apparatus and method described herein can be utilized to PVT grow a SiC single crystal boule having a first, outside diameter of at least 305 mm, e.g., between 205 mm and 305 mm; a thickness of at least 10 mm; and, within a second diameter of the SiC single crystal boule that is less than the first diameter, a total thickness variation of less than 20%, e.g., less than 10%.
  • the total thickness variation is defined as the difference between maximum and minimum values of boule thickness within the second diameter divided by the average boule thickness.
  • the second diameter can be at least 5 mm less than the first diameter.
  • the first diameter can be at least 5 mm more than the second diameter.
  • the SiC single crystal boule, and a wafer prepared (sliced) therefrom can be a 4H or 6H polytype.
  • the SiC single crystal boule can be a nitrogen-doped N-type SiC single crystal boule.
  • the SiC single crystal boule can be vanadium-doped and semi-insulating.
  • a wafer having a diameter of 200 mm can be prepared (sliced) from a 205 mm SiC single crystal boule.
  • a wafer having a diameter of 250 mm can be prepared (sliced) from a 255 mm SiC single crystal boule.
  • a wafer having a diameter of 300 mm can be prepared (sliced) from a 305 mm SiC single crystal boule.
  • a 200 mm, 250 mm, or 300 mm diameter N-type 4H-SiC wafer can be prepared in accordance with the principles described herein and can have a wafer-average micropipe density of less than 0.1 cm ⁇ 2 , e.g., less than 0.05 cm ⁇ 2 ; a wafer-average threading screw dislocation density of less than 1000 cm ⁇ 2 , e.g., less than 300 cm ⁇ 2 ; and a wafer-average basal plane dislocation density of less than 500 cm ⁇ 2 ; e.g., less than 200 cm ⁇ 2 .
  • a 200 mm, 250 mm, or 300 mm diameter n-type 4H-SiC wafer can be prepared in accordance with the principles described herein and can have a lattice curvature of less than 0.3° , e.g., less than 0.1°; and a full width at half maximum (FWHM) of a rocking curve of less than 25 arc-seconds, e.g., less than 15 arc-seconds.
  • FWHM full width at half maximum
  • a 200 mm, 250 mm, or 300 mm diameter N-type 4H-SiC wafer can be prepared in accordance with the principles described herein and can have total areas populated with stacking faults of less than 10%, e.g., less than 2% of the total wafer area.
  • a 200 mm diameter semi-insulating, vanadium doped SiC wafer can be prepared in accordance with the principles described herein and can have a micropipe density of less than 0.1 cm ⁇ 2 ; a lattice curvature of less than 0.3°, e.g., less than 0.1°; and a full width at half maximum (FWHM) of the rocking curve of less than 25 arc-seconds, e.g., less than 15 arc-seconds.
  • FWHM full width at half maximum
  • a 200 mm diameter semi-insulating, vanadium doped SiC wafer can be prepared in accordance with the principles described herein and can have a room temperature resistivity greater than 1 ⁇ 10 11 Ohm-cm.
  • a 200 mm diameter semi-insulating, vanadium doped, Nu-type 6H-SiC wafer can be prepared in accordance with the principles described herein and can have a room temperature resistivity greater than 1 ⁇ 10 11 Ohm-cm, or an activation energy of resistivity of at least 0.8 eV, or both
  • a 200 mm diameter semi-insulating, vanadium doped, Pi-type 6H-SiC wafer can be prepared in accordance with the principles described herein and can have a room temperature resistivity greater than 1 ⁇ 10 12 Ohm-cm; or an activation energy of resistivity of at least 1.2 eV, or both.
  • a 200 mm diameter semi-insulating, vanadium doped, Nu-type 4H-SiC wafer can be prepared in accordance with the principles described herein and can have a room temperature resistivity greater than 1 ⁇ 10 12 Ohm-cm; or an activation energy of resistivity of at least 1 eV, or both.
  • a 200 mm diameter semi-insulating, vanadium doped, Pi-type 4H-SiC wafer can be prepared in accordance with the principles described herein and can have a room temperature resistivity greater than 1.10 12 Ohm-cm; and an activation energy of resistivity of at least 1.5 eV, or both.

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)
  • General Chemical & Material Sciences (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
  • Crucibles And Fluidized-Bed Furnaces (AREA)
US15/584,583 2016-05-06 2017-05-02 Large Diameter Silicon Carbide Single Crystals and Apparatus and Method of Manufacture Thereof Abandoned US20170321345A1 (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
US15/584,583 US20170321345A1 (en) 2016-05-06 2017-05-02 Large Diameter Silicon Carbide Single Crystals and Apparatus and Method of Manufacture Thereof
JP2017092554A JP6373443B2 (ja) 2016-05-06 2017-05-08 大径炭化ケイ素単結晶及び装置、並びに、これらの製造方法
US16/458,385 US11035054B2 (en) 2016-05-06 2019-07-01 Large diameter silicon carbide single crystals and apparatus and method of manufacture thereof
US17/249,597 US11905618B2 (en) 2016-05-06 2021-03-05 Large diameter silicon carbide single crystals and apparatus and method of manufacture thereof
US18/415,291 US20240150931A1 (en) 2016-05-06 2024-01-17 Large diameter silicon carbide single crystals and apparatus and method of manufacture thereof

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US201662332731P 2016-05-06 2016-05-06
US15/584,583 US20170321345A1 (en) 2016-05-06 2017-05-02 Large Diameter Silicon Carbide Single Crystals and Apparatus and Method of Manufacture Thereof

Related Child Applications (1)

Application Number Title Priority Date Filing Date
US16/458,385 Division US11035054B2 (en) 2016-05-06 2019-07-01 Large diameter silicon carbide single crystals and apparatus and method of manufacture thereof

Publications (1)

Publication Number Publication Date
US20170321345A1 true US20170321345A1 (en) 2017-11-09

Family

ID=60242431

Family Applications (4)

Application Number Title Priority Date Filing Date
US15/584,583 Abandoned US20170321345A1 (en) 2016-05-06 2017-05-02 Large Diameter Silicon Carbide Single Crystals and Apparatus and Method of Manufacture Thereof
US16/458,385 Active US11035054B2 (en) 2016-05-06 2019-07-01 Large diameter silicon carbide single crystals and apparatus and method of manufacture thereof
US17/249,597 Active 2037-06-15 US11905618B2 (en) 2016-05-06 2021-03-05 Large diameter silicon carbide single crystals and apparatus and method of manufacture thereof
US18/415,291 Pending US20240150931A1 (en) 2016-05-06 2024-01-17 Large diameter silicon carbide single crystals and apparatus and method of manufacture thereof

Family Applications After (3)

Application Number Title Priority Date Filing Date
US16/458,385 Active US11035054B2 (en) 2016-05-06 2019-07-01 Large diameter silicon carbide single crystals and apparatus and method of manufacture thereof
US17/249,597 Active 2037-06-15 US11905618B2 (en) 2016-05-06 2021-03-05 Large diameter silicon carbide single crystals and apparatus and method of manufacture thereof
US18/415,291 Pending US20240150931A1 (en) 2016-05-06 2024-01-17 Large diameter silicon carbide single crystals and apparatus and method of manufacture thereof

Country Status (2)

Country Link
US (4) US20170321345A1 (ja)
JP (1) JP6373443B2 (ja)

Cited By (37)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108286074A (zh) * 2018-01-26 2018-07-17 山东大学 一种大尺寸SiC单晶生长装置及其工作方法
CN109280964A (zh) * 2018-10-16 2019-01-29 山东天岳先进材料科技有限公司 一种生长碳化硅单晶的热场结构
US20190103271A1 (en) * 2017-09-29 2019-04-04 Fuji Electric Co., Ltd. Silicon carbide semiconductor substrate, method of manufacturing a silicon carbide semiconductor device, and silicon carbide semiconductor device
CN109576782A (zh) * 2018-12-19 2019-04-05 有研工程技术研究院有限公司 一种氟化铝晶体颗粒的制备方法和应用
CN110512281A (zh) * 2019-09-26 2019-11-29 衡水学院 快速制备碳化硅的方法
WO2020077847A1 (zh) * 2018-10-16 2020-04-23 山东天岳先进材料科技有限公司 大尺寸高纯碳化硅单晶、衬底及其制备方法和制备用装置
CN111411395A (zh) * 2020-05-15 2020-07-14 南通大学 碳化硅晶体生长用石墨坩埚装置及其单晶生长方法
US10801128B2 (en) * 2017-11-24 2020-10-13 Showa Denko K.K. SiC epitaxial growth apparatus
EP3760766A1 (en) 2019-07-03 2021-01-06 SiCrystal GmbH System for efficient manufacturing of a plurality of high-quality semiconductor single crystals, and method of manufacturing same
EP3760765A1 (en) 2019-07-03 2021-01-06 SiCrystal GmbH System for horizontal growth of high-quality semiconductor single crystals, and method of manufacturing same
US20210108334A1 (en) * 2019-09-24 2021-04-15 Denso Corporation Silicon carbide single crystal wafer, and methods for manufacturing silicon carbide single crystal ingot and the silicon carbide single crystal wafer
US20210115593A1 (en) * 2018-03-16 2021-04-22 Shin-Etsu Handotai Co., Ltd. Method and apparatus for manufacturing silicon carbide single crystal
EP3816331A1 (en) * 2019-10-29 2021-05-05 SKC Co., Ltd. A sic wafer and a method for preparing a sic wafer
CN113005511A (zh) * 2021-02-23 2021-06-22 山东天岳先进科技股份有限公司 一种高质量碳化硅晶体的生长方法及装置
WO2021154484A1 (en) * 2020-01-29 2021-08-05 Cree, Inc. Dislocation distribution for silicon carbide crystalline materials
CN113818083A (zh) * 2020-06-18 2021-12-21 盛新材料科技股份有限公司 半绝缘单晶碳化硅粉末的制备方法
EP3940122A1 (en) * 2020-07-14 2022-01-19 SKC Co., Ltd. Sic wafer and method of manufacturing sic wafer
DE102020117661A1 (de) 2020-07-03 2022-01-20 Friedrich-Alexander-Universität Erlangen-Nürnberg Kristallzüchtungsanlage zur Herstellung eines Einkristalls
US20220025549A1 (en) * 2020-07-27 2022-01-27 Globalwafers Co., Ltd. Silicon carbide wafer and method of fabricating the same
EP3812488A4 (en) * 2018-06-20 2022-03-16 Shin-Etsu Handotai Co., Ltd. DEVICE FOR GROWING A SINGLE CRYSTAL OF SILICON CARBIDE AND METHOD FOR PRODUCTION OF A SINGLE CRYSTAL OF SILICON CARBIDE
US20220144711A1 (en) * 2020-01-27 2022-05-12 Free Form Fibers, Llc High purity ingot for wafer production
US20220181156A1 (en) * 2019-03-05 2022-06-09 Kwansei Gakuin Educational Foundation SiC EPITAXIAL SUBSTRATE MANUFACTURING METHOD AND MANUFACTURING DEVICE THEREFOR
WO2022132715A1 (en) * 2020-12-15 2022-06-23 Wolfspeed, Inc. Large dimension silicon carbide single crystalline materials with reduced crystallographic stress
CN114703548A (zh) * 2022-03-07 2022-07-05 浙江东尼电子股份有限公司 一种用于碳化硅制备过程的坩埚装置
CN115558986A (zh) * 2022-11-14 2023-01-03 浙江晶越半导体有限公司 一种用于提高大尺寸碳化硅籽晶生长温度均匀性的坩埚
CN117166054A (zh) * 2022-06-02 2023-12-05 株式会社力森诺科 SiC单晶基板
EP4286564A1 (en) * 2022-06-02 2023-12-06 Resonac Corporation 8-inch n-type sic single crystal substrate
US20240105512A1 (en) * 2020-10-06 2024-03-28 Globalwafers Co., Ltd. Semiconductor substrate
US12006591B2 (en) 2020-03-02 2024-06-11 Ii-Vi Advanced Materials, Llc Method for preparing an aluminum doped silicon carbide crystal by providing a compound including aluminum and oxygen in a capsule comprised of a first and second material
US12054850B2 (en) 2019-12-27 2024-08-06 Wolfspeed, Inc. Large diameter silicon carbide wafers
EP4414481A1 (en) 2023-02-08 2024-08-14 SiCrystal GmbH System for manufacturing a high-quality semiconductor single crystal, and method of manufacturing same
EP4414480A1 (en) 2023-02-08 2024-08-14 SiCrystal GmbH System for manufacturing a high-quality semiconductor single crystal, and method of manufacturing same
US20240295047A1 (en) * 2020-09-28 2024-09-05 Sec Carbon, Ltd. Sic single-crystal growth apparatus
EP4431643A1 (en) 2023-03-15 2024-09-18 SiCrystal GmbH Sublimation system and method of growing at least one single crystal
EP4431644A1 (en) 2023-03-15 2024-09-18 SiCrystal GmbH Sublimation system and method of growing at least one single crystal of a semiconductor material
US12292374B1 (en) 2024-03-28 2025-05-06 Camtek Ltd. Crystallographic defect inspection
US12534826B2 (en) * 2023-08-24 2026-01-27 Resonac Corporation SiC substrate and SiC epitaxial wafer

Families Citing this family (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10714572B2 (en) * 2016-10-04 2020-07-14 Sumitomo Electric Industries, Ltd. Silicon carbide epitaxial substrate and method for manufacturing a silicon carbide semiconductor device
JP7644779B2 (ja) 2020-05-06 2025-03-12 眉山博雅新材料股▲ふん▼有限公司 結晶の製造装置及び成長方法
CN111254486A (zh) * 2020-05-06 2020-06-09 眉山博雅新材料有限公司 一种晶体制备装置
JP2021195301A (ja) * 2020-06-18 2021-12-27 盛新材料科技股▲ふん▼有限公司Taisic Materials Corp. 半絶縁性単結晶炭化ケイ素粉末の製造方法
EP4001475A1 (en) 2020-11-19 2022-05-25 Zadient Technologies SAS Improved furnace apparatus for crystal production
WO2022123084A2 (en) * 2020-12-11 2022-06-16 Zadient Technologies SAS Method and device for producing a sic solid material
US20230295838A1 (en) * 2021-04-30 2023-09-21 Tankeblue Semiconductor Co., Ltd. High quality silicon carbide seed crystal, silicon carbide crystal, silicon carbide substrate, and preparation method therefor
EP4411029A4 (en) * 2021-09-30 2025-10-22 Central Glass Co Ltd SINGLE CRYSTAL SILICON CARBIDE WAFER, SINGLE CRYSTAL SILICON CARBIDE INGOT, AND METHOD FOR PRODUCING SINGLE CRYSTAL SILICON CARBIDE
KR102442732B1 (ko) 2021-11-05 2022-09-13 주식회사 쎄닉 탄화규소 웨이퍼 및 이의 제조방법
CN114525587B (zh) * 2022-04-22 2022-07-19 中电化合物半导体有限公司 基于pvt法生长碳化硅单晶的设备及方法
JP2023167698A (ja) * 2022-05-12 2023-11-24 株式会社デンソー 炭化珪素単結晶の製造方法および炭化珪素単結晶ウェハ
EP4279641A1 (en) 2022-05-18 2023-11-22 Zadient Technologies SAS Improved furnace apparatus for crystal production with seed holder repositioning unit
CN115110150A (zh) * 2022-05-20 2022-09-27 浙江富芯微电子科技有限公司 一种碳化硅生长装置及其坩埚保温结构
WO2024157718A1 (ja) * 2023-01-24 2024-08-02 住友電気工業株式会社 炭化珪素基板、エピタキシャル基板の製造方法および半導体装置の製造方法
WO2025049130A1 (en) 2023-08-25 2025-03-06 Cvd Equipment Corporation Pvt system with improved crucible design
JP2025034956A (ja) * 2023-08-31 2025-03-13 株式会社レゾナック ＳｉＣ単結晶ブール、ＳｉＣ単結晶ブールの製造方法及びＳｉＣ基板の製造方法
US20250222551A1 (en) 2024-01-10 2025-07-10 Globalwafers Co., Ltd. Processing method for boule and grinding equipment
WO2025225726A1 (ja) * 2024-04-26 2025-10-30 株式会社レゾナック ＳｉＣエピタキシャルウェハ、ＳｉＣエピタキシャルウェハの評価方法及びＳｉＣデバイスの製造方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6048813A (en) * 1998-10-09 2000-04-11 Cree, Inc. Simulated diamond gemstones formed of aluminum nitride and aluminum nitride: silicon carbide alloys
US6451112B1 (en) * 1999-10-15 2002-09-17 Denso Corporation Method and apparatus for fabricating high quality single crystal
US20130280466A1 (en) * 2012-04-20 2013-10-24 Ii-Vi Incorporated Large Diameter, High Quality SiC Single Crystals, Method and Apparatus

Family Cites Families (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6670282B2 (en) * 2000-03-16 2003-12-30 Denso Corporation Method and apparatus for producing silicon carbide crystal
EP1268882B1 (en) * 2000-03-13 2011-05-11 II-VI Incorporated Axial gradient transport apparatus and process for producing large size, single crystals of silicon carbide
US6805745B2 (en) 2000-03-13 2004-10-19 Ii-Vi Incorporated Large size single crystal seed crystal fabrication by intergrowth of tiled seed crystals
JP4275308B2 (ja) * 2000-12-28 2009-06-10 株式会社デンソー 炭化珪素単結晶の製造方法およびその製造装置
US7608524B2 (en) 2005-04-19 2009-10-27 Ii-Vi Incorporated Method of and system for forming SiC crystals having spatially uniform doping impurities
CN101680112A (zh) 2007-01-16 2010-03-24 Ii-Vi有限公司 借助多层生长导向器的直径导向式SiC升华生长
CN102245813B (zh) 2008-12-08 2014-08-06 Ii-Vi有限公司 改进的轴向梯度传输(agt)生长工艺和利用电阻加热的装置
EP2477944A4 (en) 2009-09-15 2013-08-28 Ii Vi Inc SUBLIMATION BREEDING OF SIC INDIVIDUAL CRYSTALS
JP5440260B2 (ja) * 2010-03-02 2014-03-12 住友電気工業株式会社 炭化珪素結晶の製造方法およびその製造装置
JP5402798B2 (ja) * 2010-04-06 2014-01-29 新日鐵住金株式会社 炭化珪素単結晶インゴットの製造方法
CN102534805B (zh) * 2010-12-14 2014-08-06 北京天科合达蓝光半导体有限公司 一种碳化硅晶体退火工艺
JP5799846B2 (ja) * 2012-02-14 2015-10-28 住友電気工業株式会社 炭化珪素単結晶の製造方法および製造装置
WO2013177496A1 (en) 2012-05-24 2013-11-28 Ii-Vi Incorporated Vanadium compensated, si sic single crystals of nu and pi type and the crystal growth process thereof
TWI609991B (zh) * 2013-06-05 2018-01-01 維克儀器公司 具有熱一致性改善特色的晶圓舟盒
US9845549B2 (en) * 2014-10-31 2017-12-19 Sumitomo Electric Industries, Ltd. Method of manufacturing silicon carbide single crystal

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6048813A (en) * 1998-10-09 2000-04-11 Cree, Inc. Simulated diamond gemstones formed of aluminum nitride and aluminum nitride: silicon carbide alloys
US6451112B1 (en) * 1999-10-15 2002-09-17 Denso Corporation Method and apparatus for fabricating high quality single crystal
US20130280466A1 (en) * 2012-04-20 2013-10-24 Ii-Vi Incorporated Large Diameter, High Quality SiC Single Crystals, Method and Apparatus

Cited By (64)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20190103271A1 (en) * 2017-09-29 2019-04-04 Fuji Electric Co., Ltd. Silicon carbide semiconductor substrate, method of manufacturing a silicon carbide semiconductor device, and silicon carbide semiconductor device
US10748763B2 (en) * 2017-09-29 2020-08-18 Fuji Electric Co., Ltd. Silicon carbide semiconductor substrate, method of manufacturing a silicon carbide semiconductor device, and silicon carbide semiconductor device
US10801128B2 (en) * 2017-11-24 2020-10-13 Showa Denko K.K. SiC epitaxial growth apparatus
CN108286074A (zh) * 2018-01-26 2018-07-17 山东大学 一种大尺寸SiC单晶生长装置及其工作方法
US20210115593A1 (en) * 2018-03-16 2021-04-22 Shin-Etsu Handotai Co., Ltd. Method and apparatus for manufacturing silicon carbide single crystal
EP3812488A4 (en) * 2018-06-20 2022-03-16 Shin-Etsu Handotai Co., Ltd. DEVICE FOR GROWING A SINGLE CRYSTAL OF SILICON CARBIDE AND METHOD FOR PRODUCTION OF A SINGLE CRYSTAL OF SILICON CARBIDE
CN109280964A (zh) * 2018-10-16 2019-01-29 山东天岳先进材料科技有限公司 一种生长碳化硅单晶的热场结构
WO2020077847A1 (zh) * 2018-10-16 2020-04-23 山东天岳先进材料科技有限公司 大尺寸高纯碳化硅单晶、衬底及其制备方法和制备用装置
CN109576782A (zh) * 2018-12-19 2019-04-05 有研工程技术研究院有限公司 一种氟化铝晶体颗粒的制备方法和应用
US20220181156A1 (en) * 2019-03-05 2022-06-09 Kwansei Gakuin Educational Foundation SiC EPITAXIAL SUBSTRATE MANUFACTURING METHOD AND MANUFACTURING DEVICE THEREFOR
US12534825B2 (en) * 2019-03-05 2026-01-27 Kwansei Gakuin Educational Foundation SiC epitaxial substrate manufacturing method and manufacturing device therefor
US11560643B2 (en) 2019-07-03 2023-01-24 Sicrystal Gmbh System for efficient manufacturing of a plurality of high-quality semiconductor single crystals by physical vapor transport
US11479875B2 (en) 2019-07-03 2022-10-25 Sicrystal Gmbh System for horizontal growth of high-quality semiconductor single crystals by physical vapor transport
EP3760766A1 (en) 2019-07-03 2021-01-06 SiCrystal GmbH System for efficient manufacturing of a plurality of high-quality semiconductor single crystals, and method of manufacturing same
EP3760765A1 (en) 2019-07-03 2021-01-06 SiCrystal GmbH System for horizontal growth of high-quality semiconductor single crystals, and method of manufacturing same
US12157955B2 (en) 2019-07-03 2024-12-03 Sicrystal Gmbh Method for simultaneously manufacturing more than one single crystal of a semiconductor material by physical vapor transport
US12071709B2 (en) * 2019-09-24 2024-08-27 Denso Corporation Methods for manufacturing silicon carbide single crystal ingot and silicon carbide single crystal wafer
US12252808B2 (en) * 2019-09-24 2025-03-18 Denso Corporation Silicon carbide single crystal wafer, and methods for manufacturing silicon carbide single crystal ingot and the silicon carbide single crystal wafer
US20210108334A1 (en) * 2019-09-24 2021-04-15 Denso Corporation Silicon carbide single crystal wafer, and methods for manufacturing silicon carbide single crystal ingot and the silicon carbide single crystal wafer
CN110512281A (zh) * 2019-09-26 2019-11-29 衡水学院 快速制备碳化硅的方法
EP3816331A1 (en) * 2019-10-29 2021-05-05 SKC Co., Ltd. A sic wafer and a method for preparing a sic wafer
US11708644B2 (en) 2019-10-29 2023-07-25 Senic Inc. Method for preparing SiC ingot, method for preparing SiC wafer and the SiC wafer prepared therefrom
US12473661B2 (en) 2019-12-27 2025-11-18 Wolfspeed, Inc. Large diameter silicon carbide wafers
US12054850B2 (en) 2019-12-27 2024-08-06 Wolfspeed, Inc. Large diameter silicon carbide wafers
US12415763B2 (en) * 2020-01-27 2025-09-16 Free Form Fibers, Llc High purity ingot for wafer production
US20220144711A1 (en) * 2020-01-27 2022-05-12 Free Form Fibers, Llc High purity ingot for wafer production
CN115298366A (zh) * 2020-01-29 2022-11-04 沃孚半导体公司 用于碳化硅晶体材料的位错分布
US11519098B2 (en) * 2020-01-29 2022-12-06 Wolfspeed, Inc. Dislocation distribution for silicon carbide crystalline materials
WO2021154484A1 (en) * 2020-01-29 2021-08-05 Cree, Inc. Dislocation distribution for silicon carbide crystalline materials
CN115298366B (zh) * 2020-01-29 2024-03-08 沃孚半导体公司 用于碳化硅晶体材料的位错分布
US12060650B2 (en) 2020-03-02 2024-08-13 Ii-Vi Advanced Materials, Llc Vanadium-compensated 4H and 6H single crystals of optical grade, and silicon carbide crystals and methods for producing same
US12006591B2 (en) 2020-03-02 2024-06-11 Ii-Vi Advanced Materials, Llc Method for preparing an aluminum doped silicon carbide crystal by providing a compound including aluminum and oxygen in a capsule comprised of a first and second material
CN111411395A (zh) * 2020-05-15 2020-07-14 南通大学 碳化硅晶体生长用石墨坩埚装置及其单晶生长方法
CN113818083A (zh) * 2020-06-18 2021-12-21 盛新材料科技股份有限公司 半绝缘单晶碳化硅粉末的制备方法
TWI794853B (zh) * 2020-07-03 2023-03-01 愛爾朗根 紐倫堡 弗里德里希 亞歷山大大學 包含成長坩堝的晶體生長設備及使用成長坩堝的方法
US12460316B2 (en) 2020-07-03 2025-11-04 Friedrich-Alexander-Universität Erlangen-Nürnberg Crystal growing unit for producing a single crystal
DE102020117661A1 (de) 2020-07-03 2022-01-20 Friedrich-Alexander-Universität Erlangen-Nürnberg Kristallzüchtungsanlage zur Herstellung eines Einkristalls
CN115768929A (zh) * 2020-07-03 2023-03-07 埃朗根-纽伦堡 弗里德里希-亚历山大大学 用于生产单晶的晶体生长单元
US11289576B2 (en) 2020-07-14 2022-03-29 Senic Inc. Wafer and method of manufactruring wafer
EP3940122A1 (en) * 2020-07-14 2022-01-19 SKC Co., Ltd. Sic wafer and method of manufacturing sic wafer
US11862685B2 (en) 2020-07-14 2024-01-02 Senic Inc. Wafer and method of manufacturing wafer
CN114108092A (zh) * 2020-07-14 2022-03-01 赛尼克公司 晶片及晶片的制造方法
US20220025549A1 (en) * 2020-07-27 2022-01-27 Globalwafers Co., Ltd. Silicon carbide wafer and method of fabricating the same
US20240295047A1 (en) * 2020-09-28 2024-09-05 Sec Carbon, Ltd. Sic single-crystal growth apparatus
US12112985B2 (en) * 2020-10-06 2024-10-08 Globalwafers Co., Ltd. Semiconductor substrate
US20240105512A1 (en) * 2020-10-06 2024-03-28 Globalwafers Co., Ltd. Semiconductor substrate
US12125701B2 (en) 2020-12-15 2024-10-22 Wolfspeed, Inc. Large dimension silicon carbide single crystalline materials with reduced crystallographic stress
KR20230118661A (ko) * 2020-12-15 2023-08-11 울프스피드, 인크. 감소된 결정학적 응력을 갖는 큰 치수의 실리콘 카바이드단결정질 재료들
KR102814591B1 (ko) * 2020-12-15 2025-05-30 울프스피드, 인크. 감소된 결정학적 응력을 갖는 큰 치수의 실리콘 카바이드 단결정질 재료들
WO2022132715A1 (en) * 2020-12-15 2022-06-23 Wolfspeed, Inc. Large dimension silicon carbide single crystalline materials with reduced crystallographic stress
CN113005511A (zh) * 2021-02-23 2021-06-22 山东天岳先进科技股份有限公司 一种高质量碳化硅晶体的生长方法及装置
CN114703548A (zh) * 2022-03-07 2022-07-05 浙江东尼电子股份有限公司 一种用于碳化硅制备过程的坩埚装置
EP4286563A1 (en) * 2022-06-02 2023-12-06 Resonac Corporation 8-inch sic single crystal substrate
US11859313B2 (en) 2022-06-02 2024-01-02 Resonac Corporation 8-inch SiC single crystal substrate
US12084789B2 (en) 2022-06-02 2024-09-10 Resonac Corporation 8-inch n-type SiC single crystal substrate
EP4286564A1 (en) * 2022-06-02 2023-12-06 Resonac Corporation 8-inch n-type sic single crystal substrate
CN117166054A (zh) * 2022-06-02 2023-12-05 株式会社力森诺科 SiC单晶基板
CN115558986A (zh) * 2022-11-14 2023-01-03 浙江晶越半导体有限公司 一种用于提高大尺寸碳化硅籽晶生长温度均匀性的坩埚
EP4414481A1 (en) 2023-02-08 2024-08-14 SiCrystal GmbH System for manufacturing a high-quality semiconductor single crystal, and method of manufacturing same
EP4414480A1 (en) 2023-02-08 2024-08-14 SiCrystal GmbH System for manufacturing a high-quality semiconductor single crystal, and method of manufacturing same
EP4431644A1 (en) 2023-03-15 2024-09-18 SiCrystal GmbH Sublimation system and method of growing at least one single crystal of a semiconductor material
EP4431643A1 (en) 2023-03-15 2024-09-18 SiCrystal GmbH Sublimation system and method of growing at least one single crystal
US12534826B2 (en) * 2023-08-24 2026-01-27 Resonac Corporation SiC substrate and SiC epitaxial wafer
US12292374B1 (en) 2024-03-28 2025-05-06 Camtek Ltd. Crystallographic defect inspection

Also Published As

Publication number Publication date
US11905618B2 (en) 2024-02-20
JP6373443B2 (ja) 2018-08-15
US20210189591A1 (en) 2021-06-24
US20190323145A1 (en) 2019-10-24
US20240150931A1 (en) 2024-05-09
JP2018039715A (ja) 2018-03-15
US11035054B2 (en) 2021-06-15

Similar Documents

Publication Publication Date Title
US20240150931A1 (en) Large diameter silicon carbide single crystals and apparatus and method of manufacture thereof
JP6663548B2 (ja) ＳｉＣ結晶及び低転位密度結晶から切断したウェハ
JP6444890B2 (ja) 低転位密度を有するｓｉｃ結晶
JP6285963B2 (ja) 昇華（ＰＶＴ）により成長させたＳｉＣ結晶での転位を減少させる方法
US7316747B2 (en) Seeded single crystal silicon carbide growth and resulting crystals
CN112746317B (zh) 碳化硅晶片、碳化硅晶锭及碳化硅晶片的制备方法
US11131038B2 (en) Furnace for seeded sublimation of wide band gap crystals
US11795572B2 (en) Method of manufacturing a silicon carbide ingot comprising moving a heater surrounding a reactor to induce silicon carbide raw materials to sublimate and growing the silicon carbide ingot on a seed crystal
US11708644B2 (en) Method for preparing SiC ingot, method for preparing SiC wafer and the SiC wafer prepared therefrom
JP4388538B2 (ja) 炭化珪素単結晶製造装置
US11359306B2 (en) Method for preparing a SiC ingot and device for preparing a SiC ingot wherein electrical resistance of crucible body is 2.9 ohms or more
EP3382068A1 (en) Silicon carbide substrate and method of growing sic single crystal boules
US20220220632A1 (en) Silicon carbide ingot manufacturing method and silicon carbide ingot manufactured thereby
CN110408997B (zh) 绝热性遮蔽构件和具备该构件的单晶制造装置
WO2015012190A1 (ja) ＳｉＣ基板の製造方法
JP2024509229A (ja) 基板上に単結晶層を製造するシステム及び方法

Legal Events

Date Code Title Description
AS Assignment

Owner name: II-VI INCORPORATED, PENNSYLVANIA

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:XU, XUEPING;ZWIEBACK, ILYA;GUPTA, AVINASH K.;AND OTHERS;REEL/FRAME:044575/0149

Effective date: 20170503

STPP Information on status: patent application and granting procedure in general

Free format text: FINAL REJECTION MAILED

AS Assignment

Owner name: BANK OF AMERICA, N.A., AS ADMINISTRATIVE AGENT, NO

Free format text: NOTICE OF GRANT OF SECURITY INTEREST IN PATENTS;ASSIGNORS:II-VI INCORPORATED;MARLOW INDUSTRIES, INC.;EPIWORKS, INC.;AND OTHERS;REEL/FRAME:050484/0204

Effective date: 20190924

Owner name: BANK OF AMERICA, N.A., AS ADMINISTRATIVE AGENT, NORTH CAROLINA

Free format text: NOTICE OF GRANT OF SECURITY INTEREST IN PATENTS;ASSIGNORS:II-VI INCORPORATED;MARLOW INDUSTRIES, INC.;EPIWORKS, INC.;AND OTHERS;REEL/FRAME:050484/0204

Effective date: 20190924

STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION

AS Assignment

Owner name: PHOTOP TECHNOLOGIES, INC., CALIFORNIA

Free format text: PATENT RELEASE AND REASSIGNMENT;ASSIGNOR:BANK OF AMERICA, N.A., AS ADMINISTRATIVE AGENT;REEL/FRAME:060574/0001

Effective date: 20220701

Owner name: II-VI OPTOELECTRONIC DEVICES, INC., NEW JERSEY

Free format text: PATENT RELEASE AND REASSIGNMENT;ASSIGNOR:BANK OF AMERICA, N.A., AS ADMINISTRATIVE AGENT;REEL/FRAME:060574/0001

Effective date: 20220701

Owner name: II-VI DELAWARE, INC., PENNSYLVANIA

Free format text: PATENT RELEASE AND REASSIGNMENT;ASSIGNOR:BANK OF AMERICA, N.A., AS ADMINISTRATIVE AGENT;REEL/FRAME:060574/0001

Effective date: 20220701

Owner name: II-VI PHOTONICS (US), INC., MASSACHUSETTS

Free format text: PATENT RELEASE AND REASSIGNMENT;ASSIGNOR:BANK OF AMERICA, N.A., AS ADMINISTRATIVE AGENT;REEL/FRAME:060574/0001

Effective date: 20220701

Owner name: M CUBED TECHNOLOGIES, INC., CONNECTICUT

Free format text: PATENT RELEASE AND REASSIGNMENT;ASSIGNOR:BANK OF AMERICA, N.A., AS ADMINISTRATIVE AGENT;REEL/FRAME:060574/0001

Effective date: 20220701

Owner name: II-VI OPTICAL SYSTEMS, INC., CALIFORNIA

Free format text: PATENT RELEASE AND REASSIGNMENT;ASSIGNOR:BANK OF AMERICA, N.A., AS ADMINISTRATIVE AGENT;REEL/FRAME:060574/0001

Effective date: 20220701

Owner name: FINISAR CORPORATION, CALIFORNIA

Free format text: PATENT RELEASE AND REASSIGNMENT;ASSIGNOR:BANK OF AMERICA, N.A., AS ADMINISTRATIVE AGENT;REEL/FRAME:060574/0001

Effective date: 20220701

Owner name: OPTIUM CORPORATION, CALIFORNIA

Free format text: PATENT RELEASE AND REASSIGNMENT;ASSIGNOR:BANK OF AMERICA, N.A., AS ADMINISTRATIVE AGENT;REEL/FRAME:060574/0001

Effective date: 20220701

Owner name: COADNA PHOTONICS, INC., PENNSYLVANIA

Free format text: PATENT RELEASE AND REASSIGNMENT;ASSIGNOR:BANK OF AMERICA, N.A., AS ADMINISTRATIVE AGENT;REEL/FRAME:060574/0001

Effective date: 20220701

Owner name: KAILIGHT PHOTONICS, INC., CALIFORNIA

Free format text: PATENT RELEASE AND REASSIGNMENT;ASSIGNOR:BANK OF AMERICA, N.A., AS ADMINISTRATIVE AGENT;REEL/FRAME:060574/0001

Effective date: 20220701

Owner name: LIGHTSMYTH TECHNOLOGIES, INC., OREGON

Free format text: PATENT RELEASE AND REASSIGNMENT;ASSIGNOR:BANK OF AMERICA, N.A., AS ADMINISTRATIVE AGENT;REEL/FRAME:060574/0001

Effective date: 20220701

Owner name: EPIWORKS, INC., ILLINOIS

Free format text: PATENT RELEASE AND REASSIGNMENT;ASSIGNOR:BANK OF AMERICA, N.A., AS ADMINISTRATIVE AGENT;REEL/FRAME:060574/0001

Effective date: 20220701

Owner name: MARLOW INDUSTRIES, INC., TEXAS

Free format text: PATENT RELEASE AND REASSIGNMENT;ASSIGNOR:BANK OF AMERICA, N.A., AS ADMINISTRATIVE AGENT;REEL/FRAME:060574/0001

Effective date: 20220701

Owner name: II-VI INCORPORATED, PENNSYLVANIA

Free format text: PATENT RELEASE AND REASSIGNMENT;ASSIGNOR:BANK OF AMERICA, N.A., AS ADMINISTRATIVE AGENT;REEL/FRAME:060574/0001

Effective date: 20220701