# US 10,483,103 B2 · Method for manufacturing a semiconductor material including a semi-polar III-nitride layer

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- Number: US 10,483,103 B2
- Document ID: US10483103B2
- Status: Granted
- Kind: B2
- Application number: 15/311,816
- Filed: 2015-05-20
- Published: 2017-03-30
- Granted: 2019-11-19
- Earliest claimed: 2014-05-20
- Assignees: Centre National de la Recherche Scientifique (CNRS)
- Applicants: Centre National De La Recherche Scientifique (CNRS)
- Inventors: Philippe De Mierry; Florian Tendille; Philippe Vennegues
- Web page: https://patentgrep.com/patent/US10483103B2

## CPC

- H10P 14/3416: {Nitrides}
- C30B 23/04: Pattern deposit, e.g. by using masks
- C30B 23/066: {Heating of the material to be evaporated}
- C30B 25/04: Pattern deposit, e.g. by using masks
- C30B 25/186: {being specially pre-treated by, e.g. chemical or physical means}
- C30B 29/406: {Gallium nitride}
- C30B 29/66: Crystals of complex geometrical shape, e.g. tubes, cylinders
- H10H 20/01335: {the light-emitting regions comprising nitride materials}
- H10H 20/825: containing nitrogen, e.g. GaN
- H10P 14/24: using chemical vapour deposition [CVD]
- H10P 14/271: {characterised by the preparation of substrate for selective deposition}
- H10P 14/278: {Pendeoepitaxy}
- H10P 14/2921: {being crystalline insulating materials}
- H10P 14/2925: {Surface structures}
- H10P 14/2926: {Crystal orientations}
- H10P 14/3216: {Nitrides}
- H10P 14/3256: {Microstructure}
- H10P 14/3258: {Crystal orientation}
- H10H 20/817: characterised by the crystal structures or orientations, e.g. polycrystalline, amorphous or porous
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- C30B: SINGLE-CRYSTAL GROWTH (by using ultra-high pressure, e.g. for the formation of diamonds, B01J3/06); UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL (zone-refining of metals or alloys C22B); PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (casting of metals, casting of other substances by the same processes or devices B22D; working of plastics B29; modifying the physical structure of metals or alloys C21D, C22F); SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (for producing semiconductor devices or parts thereof H10); APPARATUS THEREFOR
- H10H: INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS

## Abstract

The present invention relates to a method for manufacturing a semiconductor material including a semi-polar III-nitride layer from a semi-polar starting substrate including a plurality of grooves periodically spaced apart, each groove including a first inclined flank of crystallographic orientation C (0001) and a second inclined flank of different crystallographic orientation, the method comprising the phases consisting in: forming (2) III-nitride crystals on the first inclined flanks of the grooves, the growth parameters of the III-nitride crystals being adapted to favor lateral growth of said crystals such as to induce overlapping between adjacent III-nitride crystals, and continuing growth until coalescence of the III-nitride crystals to form a layer of coalesced III-nitride crystals; forming (3) a two-dimensional III-nitride layer on the layer of coalesced III-nitride crystals.

## Claims

### Claim 1

Method for manufacturing a semiconductor material including a semi-polar III-nitride layer from a starting substrate including a plurality of grooves periodically spaced apart by a distance L2, each groove including a first inclined flank of crystallographic orientation C (0001) and a second inclined flank of different crystallographic orientation, a first inclined flank of a groove and a second inclined flank of an adjacent groove forming a crenelation having a top overhung by a mask cap,
the method comprising the phases consisting in:
forming first III-nitride crystals on the first inclined flanks of the grooves, the growth parameters of the first III-nitride crystals being adapted to favor lateral growth of said first III-nitride crystals:
the growth firstly inducing triangular cavities formed between the substrate and two adjacent first III-nitride crystals, a triangular cavity having a base, two walls and a vertex, the base corresponding to the substrate, a wall corresponding to a first III-nitride crystal, another wall corresponding to said adjacent first III-nitride crystal, and the vertex corresponding to a beginning of intersection between said two adjacent first III-nitride crystals, a presence of the mask cap avoiding parasitic growth on the area covered by the mask,
and then inducing an overlapping between adjacent first III-nitride crystals, forming extended cavities situated above the triangular cavities, starting from the vertex of the triangular cavities and in line with the overlapping areas between the first III-nitride crystals in meeting planes between the first III-nitride crystals, at an intersection between two adjacent overlapping first III-nitride crystals;
forming a two-dimensional III-nitride layer on III-nitride crystals formed beforehand.

### Claim 2 (depends on 1)

Method according to claim 1, which further comprises a phase consisting in forming second III-nitride crystals on the first III-nitride crystals, the growth parameters of the second III-nitride crystals being adapted to favor lateral growth of said second III-nitride crystals to induce overlapping between adjacent second III-nitride crystals and to form cavities in line with the overlapping areas of the second III-nitride crystals.

### Claim 3 (depends on 1)

Method according to claim 1, in which growth of the first III-nitride crystals is carried out by metal organic vapour phase epitaxy MOVPE or by hydride vapour phase epitaxy HVPE, and the formation of a two-dimensional III-nitride layer is carried out by metal organic vapour phase epitaxy MOVPE, by hydride vapour phase epitaxy HVPE or by molecular beam epitaxy.

### Claim 4 (depends on 1)

Method according to claim 1, which further comprises a phase consisting in texturing the starting substrate, said phase including a step consisting in forming the plurality of grooves in the starting substrate.

### Claim 5 (depends on 4)

Method according to claim 4, in which the step consisting in forming the plurality of grooves comprises the sub-steps of:
depositing a mask of period L2 including openings,
annealing the starting substrate comprising the mask at a temperature greater than 900° C. under atmosphere comprising ammonia NH3 and/or a dihydrogen-dinitrogen H2/N2 mixture, prior to chemical etching in an acid bath,
etching the starting substrate through the openings of the mask, by introduction of the starting substrate in an acid bath to form grooves.

### Claim 6 (depends on 5)

Method according to claim 5, in which the etching sub-step comprises:
dry etching the substrate by reactive ion etching, preceded or followed by annealing under NH3, H2, N2, and
wet etching the substrate at 260° C.

### Claim 7 (depends on 5)

Method according to claim 5, in which the parameters of the step of etching the substrate are adapted to form grooves of width greater than the initial openings, thanks to lateral abrasion under the mask to form abraded areas, said grooves each including an inclined first flank of crystallographic orientation C (0001) and a second inclined flank of crystallographic orientation different to a plane C (0001).

### Claim 8 (depends on 7)

Method according to claim 7, in which the parts of the mask overhanging the abraded areas are removed by a cleaning procedure comprising treatment in an ultrasound bath, such that at the end of the cleaning procedure, the substrate comprises on its surface strips of mask with substantially vertical flanks and grooves.

### Claim 9 (depends on 5)

Method according to claim 5, in which the sub-step of depositing a mask comprises the deposition of a dielectric layer, such as a layer of SiOx, or SiNx, or a metal layer, and etching the mask to form openings.

### Claim 10 (depends on 5)

Method according to claim 5, in which the thickness of the mask layer is between 200 nm and 100 micrometers such as to block crystal defects generated from the inclined flanks.

### Claim 11 (depends on 1)

Method according to claim 1, in which the phase consisting in forming first III-nitride crystals comprises the steps consisting in:
depositing a III-nitride buffer layer by metal organic vapour phase epitaxy MOVPE of a III-nitride layer at a temperature less than 750° C.;
thermally annealing the buffer layer at a temperature greater than 950° C. under atmosphere comprising hydrogen such as to bring about the solid phase migration of the buffer layer to the first inclined flank of orientation C of each groove and thereby forming first seeds of crystallographic orientation C (0001) on the first flanks of the grooves.

### Claim 12 (depends on 11)

Method according to claim 11, in which the phase consisting in forming first III-nitride crystals comprises a step consisting in growing first III-nitride crystals on the first seeds, and in which the step consisting in growing first III-nitride crystals is implemented at a temperature between 900° C. and 1300° C., at a pressure between 0.2×105 Pa and 1×105 Pa.

### Claim 13 (depends on 12)

Method according to claim 12, in which the phase consisting in forming first III-nitride crystals comprises a step of oriented growth to favour a rate of growth of the first III-nitride crystals along crystallographic planes (0001) greater than the rates of growth of the first III-nitride crystals along planes perpendicular to (0001), such as the crystallographic planes (1120).

### Claim 14 (depends on 2)

Method according to claim 2, in which the phase consisting in forming second III-nitride crystals comprises the steps consisting in:
depositing a second SiNx layer on the pre-existing first III-nitride crystals, by exposure to silane and NH3, at a temperature greater than 950° C.,
depositing at a temperature less than 750° C. a second III-nitride buffer layer on the second SiNx layer,
thermally annealing the second buffer layer at a temperature greater than 950° C. under atmosphere comprising hydrogen such as to bring about the solid phase migration of the buffer layer to the faces a (1120) and c (0001) of the crystals, and thereby to form second seeds on the faces a (1120) and c (0001) of the first III-nitride crystals.

### Claim 15 (depends on 14)

Method according to claim 14, in which the phase consisting in forming second III-nitride crystals comprises a step consisting in growing second III-nitride crystals on the second seeds, implemented at a temperature between 900° C. and 1300° C., at a pressure between 0.2×105 Pa and 1×105 Pa.

### Claim 16 (depends on 15)

Method according to claim 15 in which the phase consisting in forming the second III-nitride crystals comprises a step of oriented growth to favour a rate of growth of the second crystals along crystallographic planes (0001) greater than the rates of growth of the III-nitride second crystals along planes perpendicular to (0001), such as the crystallographic planes (1120).

### Claim 17 (depends on 1)

Method according to claim 1, in which the starting substrate is a sapphire substrate of crystallographic orientation r (1102) having a disorientation with respect to the nominal plane being able to be 3°.

### Claim 18

Semiconductor material including a semi-polar GaN layer, self-supporting or epitaxied on an exogenous substrate, the semiconductor material comprising a semi-polar GaN layer including coalesced III-nitride crystals and triangular cavities formed between the substrate and the III nitride crystals, wherein adjacent III-nitride crystals are overlapping, wherein said semiconductor material comprises, after coalescence of the overlapping III-nitride crystals, extended cavities in meeting planes between the III-nitride crystals, at an intersection between two adjacent III-nitride crystals, and in which each extended cavity situated above the triangular cavities extends in line with the overlapping areas between the III-nitride crystals.

### Claim 19 (depends on 18)

Semiconductor material according to claim 18, in which each extended cavity extends in a plane that overhangs at least a plane defined by a crystallographic facet (0001) of the substrate.

### Claim 20 (depends on 18)

Semiconductor material according to claim 18, in which the III-nitride layer comprises a curve of X-ray diffraction intensity of the crystallographic planes {11-22} as a function of the incidence angle of the X-ray beam on these planes having a full width at half maximum less than 400 arc seconds.

### Claim 21 (depends on 1, 18)

Semiconductor material according to claim 18, obtained by the method of claim 1, said semiconductor material having a dislocation density less than or equal to 1.3×108 cm−2, preferably even less than 7×107 cm−2.

### Claim 22 (depends on 1, 18)

Semiconductor material according to claim 18, obtained by the method of claim 1, said semiconductor material having a density of non-radiating centers measured by cathodoluminescence less than or equal to 1.1×108 cm−2, preferably even less than 5×107 cm−2.

### Claim 23 (depends on 1, 18)

Semiconductor material according to claim 18 obtained by the method of claim 1, said semiconductor material having a stacking fault density determined by a transmission electron microscopy measurement less than or equal to 1×103 cm−1, preferably less than or equal to 70 cm−1.