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WO2016090223A1 - Substrats de nitrure du groupe iii et leur procédé de fabrication - Google Patents

Substrats de nitrure du groupe iii et leur procédé de fabrication Download PDF

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Publication number
WO2016090223A1
WO2016090223A1 PCT/US2015/063937 US2015063937W WO2016090223A1 WO 2016090223 A1 WO2016090223 A1 WO 2016090223A1 US 2015063937 W US2015063937 W US 2015063937W WO 2016090223 A1 WO2016090223 A1 WO 2016090223A1
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Prior art keywords
group iii
iii nitride
plane
nonpolar
semipolar
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Tadao Hashimoto
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Seoul Semiconductor Co Ltd
SixPoint Materials Inc
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Seoul Semiconductor Co Ltd
SixPoint Materials Inc
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Priority to CN201580065648.XA priority Critical patent/CN107002275B/zh
Priority to JP2017529048A priority patent/JP6456502B2/ja
Publication of WO2016090223A1 publication Critical patent/WO2016090223A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
    • C30B25/02—Epitaxial-layer growth
    • C30B25/18—Epitaxial-layer growth characterised by the substrate
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/10—Inorganic compounds or compositions
    • C30B29/40—AIIIBV compounds wherein A is B, Al, Ga, In or Tl and B is N, P, As, Sb or Bi
    • C30B29/403—AIII-nitrides
    • C30B29/406—Gallium nitride
    • 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
    • C30B7/00—Single-crystal growth from solutions using solvents which are liquid at normal temperature, e.g. aqueous solutions
    • C30B7/10—Single-crystal growth from solutions using solvents which are liquid at normal temperature, e.g. aqueous solutions by application of pressure, e.g. hydrothermal processes
    • C30B7/105—Single-crystal growth from solutions using solvents which are liquid at normal temperature, e.g. aqueous solutions by application of pressure, e.g. hydrothermal processes using ammonia as solvent, i.e. ammonothermal 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
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02367—Substrates
    • H01L21/0237—Materials
    • H01L21/02387—Group 13/15 materials
    • H01L21/02389—Nitrides
    • 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
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02518—Deposited layers
    • H01L21/02521—Materials
    • H01L21/02538—Group 13/15 materials
    • H01L21/0254—Nitrides
    • 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
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02612—Formation types
    • H01L21/02617—Deposition types
    • H01L21/02636—Selective deposition, e.g. simultaneous growth of mono- and non-monocrystalline semiconductor materials
    • H01L21/02639—Preparation of substrate for selective deposition
    • 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
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02612—Formation types
    • H01L21/02617—Deposition types
    • H01L21/02636—Selective deposition, e.g. simultaneous growth of mono- and non-monocrystalline semiconductor materials
    • H01L21/02647—Lateral overgrowth
    • 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
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02367—Substrates
    • H01L21/0237—Materials
    • H01L21/0242—Crystalline insulating materials

Definitions

  • the invention relates to a substrate of semiconductor material used to produce semiconductor devices including optoelectronic devices such as light emitting diodes (LEDs) and laser diodes (LDs), and electronic devices such as transistors. More specifically, the invention provides substrates of group III nitride such as gallium nitride. The invention also provides methods of making these substrates.
  • Gallium nitride (GaN) and its related group III nitride alloys are the key material for various optoelectronic and electronic devices such as LEDs, LDs, microwave power transistors, and solar-blind photo detectors.
  • LEDs are widely used in displays, indicators, general illuminations, and LDs are used in data storage disk drives.
  • Recently, researchers have demonstrated GaN with m-plane (nonpolar), a-plane (nonpolar), angled m- plane (semipolar), or angled a-plane (semipolar) shows higher indium incorporation when solid solution of InGaN is grown. Higher indium content is required to fabricate light emitting devices with longer wavelength such as green, amber and even red.
  • nonpolar and semipolar substrates there are a few approaches.
  • One is to use non-c-plane heterogeneous substrate such as r-plane sapphire, m-plane silicon carbide to grow GaN by vapor phase epitaxy [1]. Since large diameter (>2") wafers of these materials are commercially available, it is relatively easy to obtain large-area nonpolar/semipolar GaN on such substrates.
  • a-plane GaN can be grown on r- plane sapphire and m-plane GaN can be grown on m-plane SiC.
  • This approach also provides relatively large-area nonpolar/semipolar GaN layers.
  • these approaches inevitably introduce basal plane stacking fault, which propagates parallel to c-plane of GaN.
  • Typical density of the stacking faults are 10 5 cm "1 , which means the average spacing of the stacking faults is 0.1 microns.
  • scientists have proven that the stacking faults become non-radiative recombination center, thus optical devices fabricated on such material does not have high efficiency.
  • this approach typically provides long strips of wafers. For example, if 2" diameter x 5 mm thick bulk GaN crystal is sliced to obtain m- plane wafers, the largest piece one can obtain is a 2" x 5 mm rectangular strip. Although this strip contains negligible amount of stacking faults, the shape and size is not favorable for commercial application.
  • the invention provides a group III nitride substrate having a first side of nonpolar or semipolar plane and a second side opposite to the first side has more than one stripe of metal buried wherein the direction of the stripes is perpendicular to the c- axis of the group III nitride.
  • the invention provides a group III nitride substrate having a first side of nonpolar or semipolar plane and a second side opposite to the first side exposes a nonpolar or semipolar plane.
  • the substrate has more than one stripes of metal buried inside the substrate wherein the direction of the stripes is perpendicular to the c-axis of the group III nitride.
  • the invention provides a group III nitride substrate having a first side of nonpolar or semipolar plane and a second side opposite to the first side exposes a nonpolar or semipolar plane.
  • the substrate contains bundles of stacking faults with spacing of the bundles larger than 1 mm.
  • the bundles may be spaced apart by at least 1.5, 2.0, 2.5, 3, 3.5, 4, 4.5, or 5 mm in order to provide large, cluster-free regions in which an electronic device can be formed.
  • the invention also provides methods of fabricating the group III nitride substrate.
  • One such method comprises growing a group III nitride bulk crystal along the c- direction, covering the group III polar c-plane with metal, slicing the group III nitride bulk crystal along nonpolar or semipolar direction to obtain plurality of strips, fixing the strips on a frame with keeping a certain spacing and the same crystallographic planes aligned to the same direction, and growing group III nitride crystal in supercritical ammonia.
  • group III nitride crystal grows on the nitrogen polar c- planes with optional growth on the nonpolar/semipolar planes.
  • the growth along -c direction fuses the strips together to make one piece of wafer.
  • FIG. 1 is a schematic cross-sectional drawing of a group III nitride substrate.
  • each number represents the folio wings:
  • FIG. 2 is a schematic cross-sectional drawing of a group III nitride substrate.
  • each number represents the followings: 11.
  • FIG. 3A through 3D is an example of part of steps to fabricate a group III nitride substrate.
  • FIG. 4A and 4B are schematic drawings of fixing nonpolar/semipolar strips on a frame.
  • FIG. 4A is a top view and
  • FIG. 4B is a side view.
  • FIG. 5A through 5E is an example of part of steps to fabricate a group III nitride substrate. These figures are side views.
  • each number represents the followings: 11.
  • I I A A first side of the substrate exposing nonpolar/semipolar surface, 1 IB. A second side opposite to the first side,
  • Group III nitride substrate obtained from the piece of group III nitride crystal
  • the group III nitride substrate of the present invention is typically used for optoelectronic and electronic devices.
  • a group III nitride substrate having nonpolar or semipolar orientations are preferred.
  • Typical nonpolar orientations are m ⁇ 10-10 ⁇ planes and a ⁇ l 1-20 ⁇ plane
  • typical semipolar orientations are ⁇ 11-22 ⁇ , ⁇ 11-2-2 ⁇ , ⁇ 10-13 ⁇ , ⁇ 10-1-3 ⁇ , ⁇ 20-21 ⁇ , and ⁇ 20- 2-1 ⁇ planes.
  • This invention can also provide a substrate with other nonpolar/semipolar orientations.
  • the group III nitride substrate in this invention provides a large-area substrate having a suitable nonpolar/semipolar surface for device fabrication.
  • a method of fabricating the substrate involves growing a group III nitride bulk crystal on a c-plane, covering the group III polar c-plane with metal, slicing the group III nitride bulk crystal to obtain strips of nonpolar/semipolar orientations, re-aligning the strips with maintaining a certain spacing, followed by growth in supercritical ammonia. This way, generation of polycrystals during crystal growth is minimized.
  • Stacking faults primarily exist as bundles over the metal strips, thus providing a larger usable area for devices.
  • the invention in one instance provides a new group III nitride substrate.
  • the substrate has a nonpolar or semipolar surface on which a device such as an LED and/or LD can be formed.
  • the substrate has a plurality of regions with clusters (bundles) of stacking faults.
  • the substrate also has open regions between clusters that are free of bundles of stacking faults, and these regions are sufficiently large that an electronic device such as an LED or LD can be formed without intersecting a bundle of stacking faults.
  • the open regions have relatively few stacking faults in those regions, with e.g. at least 80% or at least 90%) of the stacking faults being clustered outside of the open regions.
  • An LED or LD fabricated in an open region can therefore have better efficiency than an LED or LD fabricated on a comparative substrate that is otherwise identical but does not have bundles of stacking faults.
  • FIG. 1 shows a schematic of one group III nitride substrate (11) according to the invention.
  • a first side (HA) exposes a nonpolar or semipolar surface with a miscut angle less than +/- 5 degrees.
  • the miscut is sometimes preferred to obtain higher crystal quality and surface smoothness after epitaxial growth.
  • the miscut angle can be along +c direction, - c direction or directions perpendicular to the c direction.
  • the crystal has a second side (1 IB) opposite to the first side which may expose metal strips aligned perpendicular to the c-axis.
  • the substrate may have a second side exposing a nonpolar/semipolar plane. In this case, metal stripes are embedded inside the substrate.
  • the portion of the metal may be completely removed so that only nonpolar/semipolar surfaces are exposed on the first and second side, and metal stripes do not exist in the substrate as shown in FIG. 2.
  • bundles of stacking faults remain in the substrate with spacing larger than 1 mm or preferably 5 mm.
  • the substrate in this invention is large enough for practical device fabrication. Since the stacking faults are bundled in a limited region, usable area for device fabrication is also sufficient for practical use.
  • the surface on the first side is used for epitaxial growth and is typically polished to achieve epi-ready condition. Conventional grinding, lapping and chemical mechanical polishing (CMP) are used to polish the surface.
  • CMP chemical mechanical polishing
  • the second side may be polished or may be left unpolished.
  • the substrate may be round shape, rectangular shape, square shape, hexagonal shape or other shapes. Also, the substrate may have one or more orientation flats to identify crystallographic orientations.
  • the substrate may have in-plane lattice bending, which discontinues at the bundles of stacking faults.
  • the substrate may be electrically conductive (n-type or p-type) or semi-insulating, depending of the application.
  • the invention provides a new method of forming a substrate of this invention.
  • the method involves placing group III nitride pieces so that fast-growing edges of the pieces face one another across a gap, and growing group III nitride on one but not the other of the fast-growing edges facing one another in order to fill the gap with group III nitride.
  • the method may also comprise continuing to grow group III nitride to merge the pieces into a single substrate, and growing additional group III nitride on a face formed by the merged strips.
  • Piece edges may be masked individually to prevent growth on one or more edges, or a substrate may be masked and then cut into pieces to provide an edge on which group III nitride does not grow.
  • the group III nitride may be grown by an
  • ammonothermal method such as an ammonobasic or an ammonoacidic method
  • the pieces are at least merged into a single substrate using either of these ammonothermal methods.
  • Additional group III nitride may be grown on a face formed by the merged pieces using an ammonothermal method (basic or acidic), and/or additional group III nitride may be grown on the face via a fast-growth method such as vapor-phase epitaxy (e.g. HVPE, MOCVD), MBE, a flux method, high-pressure solution growth or sputtering.
  • vapor-phase epitaxy e.g. HVPE, MOCVD
  • MBE a flux method, high-pressure solution growth or sputtering.
  • the invention also provides pieces having an edge masked with e.g. a metal to prevent growth of group III nitride on that edge.
  • the masked edge may be one that is fast- growing in an ammonothermal method, particularly an ammonobasic method or an ammonoacidic method.
  • a plurality of these pieces can be used in practicing a method according to the invention.
  • the pieces may be in the form of strips cut from a substrate.
  • FIG.3A through 3D shows a part of one fabrication method for a substrate of this invention.
  • a seed crystal (31) is prepared. If ammonothermal growth is used to grow a group III nitride bulk crystal on the seed, the seed crystal (31) is preferably group III nitride. If a growth method which is compatible with heterogeneous substrates such as sapphire, silicon carbide (SiC), gallium arsenide (GaAs), or silicon (Si) is used to grow a bulk crystal of group III nitride, the seed crystal (31) can be such heterogeneous substrate.
  • Hydride vapor phase epitaxy (HVPE), flux method, or high-pressure solution growth are examples of growth method compatible with heterogeneous substrates.
  • the seed crystal should be suitable to grow group III nitride along c-axis direction without introducing stacking faults.
  • group III nitride seed c-plane GaN or c-plane A1N may be used.
  • heterogeneous substrates c-plane sapphire, c-plane SiC, (111) plane GaAs, or (111) Si may be used.
  • the group III polar surface of the seed crystal may be masked with metal (32) so that a bulk crystal of group III nitride grows primarily on nitrogen polar c-plane (FIG. 3B).
  • metal 32
  • a bulk crystal of GaN is grown in the ammonothermal method
  • a single crystalline GaN seed is preferably used.
  • the Ga face of the seed is covered with metal, and bulk GaN crystal is grown on N face of the seed.
  • the group III polar surface may be masked after the bulk growth. (33) shown in FIG.
  • 3C is a bulk crystal of group III nitride with group III polar surface masked with metal.
  • the bulk crystal may be formed using an ammonobasic solution, in which a basic mineralizer such as sodium, lithium, or sodium amide is added to ammonia.
  • the metal is preferably stable in supercritical ammonia. Vanadium, vanadium alloy, nickel, nickel alloy, silver, or silver alloy are examples of such metal.
  • To place the metal on the group III polar c-plane vacuum evaporation, sputtering, or plating can be used.
  • the thickness of the mask is preferably between 0.05 to 1000 microns. If the mask is too thin, it will be unstable in the supercritical ammonia. If the mask is too thick, number of stacking faults in the substrate may increase.
  • binding metal such as chromium can be used between the group III polar surface and the metal mask.
  • the bulk crystal of group III nitride with the metal mask on its group III polar c- plane is sliced to obtain strips of nonpolar/semipolar wafers (FIG. 3D). Multiple wire saw is preferably used since it can produce many strips in one step.
  • the slicing thickness is preferably about 500 microns, although it can be thinner or thicker.
  • After slicing the bulk crystal many strips of nonpolar/semipolar wafers are obtained. These wafers are optionally polished on the exposed nonpolar/semipolar planes.
  • nitrogen polar c-plane can be polished, preferably before slicing. These polishing step will expose smooth surfaces on which group III nitride will be crystallized. The polishing helps prevent polycrystalline growth on the exposed surfaces.
  • nonpolar/semipolar orientations having exposed nitrogen polar c-plane are obtained.
  • FIG. 4A is a top view
  • FIG. 4B is a side view.
  • the strips are preferably fixed with mechanical means such as screws, clamps, plates or wires. This is because the ammonothermal growth environment is too reactive to allow glues or chemical bonds. Extra care should be taken to align the strips so that
  • the misalignment angle is preferably less than 1 degree, more preferably less than 0.1 degrees.
  • the holder or frame is preferably made of metal such as vanadium, vanadium alloys, nickel, nickel alloys, silver, or silver alloys, which are compatible with the ammonothermal growth environment.
  • the holder or frame can be made of other material with appropriate coating or lining by the compatible metals listed above.
  • the shape of the frame can be hexagonal, round, or other shapes.
  • the holder does not necessarily have an opening, rather the holder can be a blank plate of appropriate size and shape that has a fastener such as a clasp or grip. In this case, only one side of the
  • the array of nonpolar/semipolar strips fixed on the frame is loaded in an ammonothermal growth reactor and crystal growth is conducted.
  • group III nitride crystal primarily grow on the nitrogen polar c-planes (42). This growth direction is indicated as the arrow (51).
  • Group III nitride crystal also grows on the exposed nonpolar/semipolar planes (43), of which the growth direction is indicated an arrow (52).
  • the growth rate along the arrow (52) is comparable to that along the arrow (51). In the case of m-plane, growth rate on the m- plane is approximately 1/10 of that of c-plane.
  • the growth front on the nitrogen polar c-plane reaches the metal surface of the adjacent strip.
  • the array of strips forms a piece of group III nitride crystal (53) as shown in FIG. 5B.
  • the coalescence front often causes defects such as stacking faults and dislocations.
  • stacking faults exists over the metal portion, forming a bundle.
  • a thin layer of InGaN may, if desired, be formed on a major face of the substrate by adding In into the reactor using a high-pressure pump toward the end of crystal growth.
  • the piece of crystal is then removed from the frame (FIG. 5C). After appropriate shaping of the crystal (54), one obtains a nonpolar/semipolar group III nitride substrate (55) as shown in FIG. 5D.
  • the second side (backside) of the substrate is optionally ground and lapped to expose the metal strips as shown in FIG. 5E. If the metal strip portion is completely removed, one can obtain a nonpolar/semipolar group III nitride substrate shown in FIG. 2.
  • a c-plane GaN seed having thickness of about 450 microns is prepared.
  • the seed has a hexagonal shape with flat to flat dimension of approximately 50 mm.
  • the sidewalls of the seed are m-planes.
  • the nitrogen polar c-plane is polished with lapping using diamond slurry.
  • the final lapping step uses diamond slurry with 0.5 micron average size.
  • the Ga polar c-plane is coated with silver using an electron beam evaporator.
  • the thickness of the silver layer is approximately 0.1 microns.
  • This seed crystal is loaded in an ammonothermal reactor to grow bulk GaN on the nitrogen polar c-plane.
  • a bulk crystal of GaN is grown at about 550 °C by using a conventional ammonothermal growth.
  • a bulk crystal of GaN having thickness of approximately 5 mm is grown on the nitrogen polar c-plane of the seed. Also, the lateral size of the crystal increases by about 500 microns. Then, the bulk crystal is sliced with a multiple wire saw. Since the as grown surface of nitrogen polar c-plane has some roughness, the crystal is mounted on the Ga-polar c-plane. Using the wire pitch of 670 microns, m-plane GaN strips having thickness of about 500 microns are obtained. The miscut angle was within +/- 5 degrees. The m-plane GaN strips have exposed nitrogen polar c-plane, m-planes and a- plane.
  • the Ga polar c-plane is covered with the silver mask.
  • the width of the strips is approximately 5 mm.
  • the m-plane GaN strips are now mounted on a lapping base with wax. Six strips are mounted so that the exposed m-planes of several pieces are lapped at one time. Then, the other side of the strips is lapped in the same way, followed by CMP. Since
  • nonpolar/semipolar planes shows different CMP characteristics than that on the Ga-polar c- planes, the polishing conditions are adjusted to obtain reasonably smooth surface of m- planes.
  • the six strips are mounted on a silver coated frame made of Ni-Cr superalloy.
  • the entire exposed surface of the frame is coated with silver; however, the frame can have uncoated portion up to about 10% as long as the deposition of GaN on the frame does not disturb the crystal growth on the strips.
  • the strips are mounted with clamping plates and screws.
  • the frame has guiding grooves so that the metal side of the strip is aligned against the groove. This way, the misalignment of the strips is maintained less than 1 degree or more preferably 0.1 degrees.
  • the lapping and CMP process of the strips also help to provide uniform thickness of the strips, thus helping the clamping work.
  • the spacing of the strips is about 5 mm, i.e. the distance between the nitrogen polar c- plane to the metal of the adjacent strip is approximately 5 mm.
  • GaN is grown on nitrogen polar c-plane until it reaches the metal surface of the adjacent piece. During this c-plane growth, stacking faults are not newly introduced. Upon coalescence, however, stacking faults are introduced.
  • the separation of the stacking fault bundles is about 10 mm.
  • the growth thickness along the m-plane is about 500 microns.
  • the total thickness of the piece of GaN crystal becomes about 1.5 mm along the m-direction.
  • the piece of crystal After removing the piece of GaN crystal from the frame, the piece of crystal is shaped into a round shape and the backside (a second side) of the piece is ground to remove the metal masks, leaving a m-plane GaN substrate having diameter of 2" and thickness of 450 microns. Then, the first side of the substrate is lapped and polished.
  • the backside (a second side) of the piece is ground to remove the metal masks, leaving a m-plane GaN substrate having diameter of 2" and thickness of 450 microns. Then, the first side of the substrate is lapped and polished.
  • Example 3 Instead of slicing the bulk GaN in Example 1 along m-plane, it is sliced along semipolar (10-1-2) plane with miscut angle less than +/- 4 degrees. Following the similar steps in Example 1, a semipolar (10-1-2) GaN substrate is fabricated.
  • Example 3
  • Example 4 Similar to the Example 1, a piece of GaN crystal is fabricated and removed from the frame. Then, by using a wire saw, the piece is sliced into half to make two m-plane GaN substrates. The surface exposing the metal was ground to remove the metal portion and then, the other side is lapped and polished to make two m-plane GaN substrates.
  • Example 4 Similar to the Example 1, a piece of GaN crystal is fabricated and removed from the frame. Then, by using a wire saw, the piece is sliced into half to make two m-plane GaN substrates. The surface exposing the metal was ground to remove the metal portion and then, the other side is lapped and polished to make two m-plane GaN substrates.
  • Example 4 Similar to the Example 1, a piece of GaN crystal is fabricated and removed from the frame. Then, by using a wire saw, the piece is sliced into half to make two m-plane GaN substrates. The surface exposing the metal was ground to remove the metal portion and then, the
  • HVPE is used in this example.
  • C-plane sapphire is used as a seed crystal.
  • C-plane GaN layer is grown on c-plane sapphire at about 1000 °C in a HVPE reactor with appropriate buffer layer in between.
  • HVPE growth reactor is found in a U.S. patent No. 8,764,903 B2. After growing approximately 5 mm-thick GaN on sapphire, it was removed from the HVPE reactor. Then, the sapphire is removed by grinding. It takes about 2 hours to remove the sapphire seed of about 450 microns.
  • the rough surface of the as-grown Ga- polar c-plane is flattened with grinding followed by sputtering of silver on it.
  • the thickness of the silver is about 0.5 microns.
  • the nitrogen polar c-plane is lapped and polished to obtain epi-ready surface.
  • the bulk GaN crystal with metal mask on the Ga-polar surface is sliced with a wire saw, and similar to the steps in Example 1 , m-plane GaN substrate is obtained.
  • the nonpolar/semiplar group III nitride substrate in this invention provides a large usable area for devices by limiting the number and location of stacking faults.
  • group III nitride By using the ammonothermal growth of group III nitride on the nitrogen polar c-plane, the plurality of nonpolar/semipolar strips coalesces without forming poly crystals at the coalescence front. Also, this scheme does not introduce stacking faults until the nitrogen polar c-plane reaches the metal of the adjacent strip.
  • the nonpolar/semipolar group III nitride substrate in this invention enables to fabricate light emitting devices having longer emission wavelength and other devices having different characteristics than those on c- plane GaN.
  • ammonothermal growth and HVPE as a bulk growth method
  • other methods such as a flux method or high-pressure solution growth can be used.
  • the preferred embodiment describes spacing of the nonpolar/semipolar strips is 5 mm, other dimensions can be selected as long as the coalescence occurs. For example, if the thickness of the bulk crystal is about 0.5 mm, and the spacing is 0.5 mm, after coalescence the spacing of the stacking fault bundle becomes about 1 mm. Likewise, 2.5 mm- wide strips with 2.5 mm spacing will make 5 mm separation of the stacking fault bundles. In addition, the width and spacing can be different value, such as 2 mm- wide strips with 5 mm spacing.
  • the preferred embodiment describes a metal thickness of 0.1 microns or 0.5 microns, other thickness can be selected as long as the metal works as a stable mask. For example, if silver plating is used, the thickness is about 1 micron or more.
  • a crystalline group III nitride substrate comprising,
  • a group III nitride substrate comprising,
  • a plurality of strips of group III nitride having a metal coating on a first long edge of each of the strips and no metal coating on a second long edge of each of the strips.
  • a piece comprising a first strip and a second strip of said plurality of any of paragraphs 19-21 merged together with additional group III nitride on the second long edge of the first strip such that the new group III nitride contacts the metal coating on the first long edge of the second strip.
  • a method of fabricating a nonpolar or semipolar group III nitride substrate comprising
  • first and second group III nitride pieces are formed from a masked substrate that is cut to form said first and second group III nitride pieces.
  • a method according to any one of paragraphs 23-28 wherein the act of growing the group III nitride on one but not the other of the fast-growing edges is performed by an ammonothermal method.
  • a method according to paragraph 29 wherein the ammonothermal method is an ammonobasic method.
  • first and second group III nitride pieces are formed by slicing a group III nitride bulk crystal along a nonpolar or semipolar plane to obtain a plurality of strips of group III nitride crystals, wherein the bulk crystal has a thickness of at least 0.5 mm and has a metal covering on a group III polar c-plane surface of the bulk crystal, and wherein the metal covering covers a group III polar c-plane surface of each of the strips.
  • a method according to paragraph 31 wherein the group III nitride bulk crystal with its metal covering is formed by growing a bulk crystal on a c-plane seed crystal and subsequently covering the group III polar c-plane surface of the crystal with the metal covering.
  • a method according to paragraph 31 wherein the group III nitride bulk crystal with its metal covering is formed by growing a bulk crystal of group III nitride on a c- plane seed crystal having its group III polar c-plane covered with the metal.
  • a method of fabricating a nonpolar/semipolar group III nitride substrate comprising;

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Abstract

L'invention concerne un substrat de nitrure du groupe III ayant un premier côté de plan non polaire ou semi-polaire et un second côté qui a plus d'une bande de métal enfouie, dans lequel les bandes sont perpendiculaires à l'axe c du nitrure du groupe III. Plus de 90 % de défauts d'empilement existent sur les bandes métalliques. Le second côté peut exposer un plan non polaire ou semi-polaire. L'invention concerne également un substrat de nitrure du groupe III ayant un premier côté de plan non polaire ou semi-polaire et un second côté avec un plan non polaire ou semi-polaire exposé. Le substrat contient des faisceaux de défauts d'empilement avec un espacement supérieur à 1 mm L'invention concerne également des procédés de fabrication des substrats de nitrure du groupe III ci-dessus.
PCT/US2015/063937 2014-12-04 2015-12-04 Substrats de nitrure du groupe iii et leur procédé de fabrication Ceased WO2016090223A1 (fr)

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EP4108812A1 (fr) * 2021-06-24 2022-12-28 Instytut Wysokich Cisnien Polskiej Akademii Nauk Procédé permettant de réduire une croissance latérale des cristaux
EP4144893A1 (fr) * 2021-09-06 2023-03-08 Instytut Wysokich Cisnien Polskiej Akademii Nauk Procédé pour réduire ou supprimer les fissures pendant le processus de tirage de cristaux et pièce métallique formée à utiliser dans ce procédé

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EP4108812A1 (fr) * 2021-06-24 2022-12-28 Instytut Wysokich Cisnien Polskiej Akademii Nauk Procédé permettant de réduire une croissance latérale des cristaux
EP4144893A1 (fr) * 2021-09-06 2023-03-08 Instytut Wysokich Cisnien Polskiej Akademii Nauk Procédé pour réduire ou supprimer les fissures pendant le processus de tirage de cristaux et pièce métallique formée à utiliser dans ce procédé

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