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US6163557A
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Fabrication of group III-V nitrides on mesas
Assignee: BLUESTONE INNOVATIONS HOLDINGS LP
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Filing: 1998-05-21
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Granted: 2000-12-19
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Expires: 2018-05-21
Abstract
Abstract Group III-V nitride films are fabricated on mesas patterned either on substrates such as sapphire substrates, or on mesas patterned on group III-V nitride layers grown on substrates. The mesas provide reduced area surfaces for epitaxially growing group III-V nitride films, to reduce thermal film stresses in the films to reduce cracking. The surfaces of the mesas on which the films are grown are dimensioned and oriented to reduce the number of thin film crack planes that can grow on the mesas. Further cracking reduction in the films can be achieved by thinning the substrate to form membranes. The reduced substrate thickness at the membranes reduces the thermal expansion mismatch tensile stress in the films. The mesas can reduce or eliminate the occurrence of cracks in GaN or AlGaN epitaxial films grown on the mesas, for percentages of aluminum in the AlGaN films of up to about 18%. The improved group III-V nitride films can be used in optoelectronic devices including LEDs and edge and surface emitting laser diodes.
Inventors
- 👤 Clarence J. Dunnrowicz
- 👤 Linda T. Romano
- 👤 David P. Bour
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 16:26
CPC Classifications
C; C30; C30B; C30B25/00; C30B25/02; C30B29/00; C30B29/10; C30B29/40; C30B29/403; C30B29/406; H; H01; H01S; H01S5/00; H01S5/20; H01S5/22; H01S5/2201; H01S5/30; H01S5/32; H01S5/3202; H01S5/32025; H10; H10H; H10H20/00; H10H20/01; H10H20/011; H10H20/013; H10H20/0133; H10H20/01335; H10P; H10P14/00; H10P14/20; H10P14/29; H10P14/2901; H10P14/2921; H10P14/2926; H10P14/32; H10P14/3202; H10P14/3214; H10P14/3216; H10P14/34; H10P14/3402; H10P14/3414; H10P14/3416; H10P14/3466; H01S5/02; H01S5/0206; H01S5/0207; H01S5/0213; H01S5/0217; H01S5/024; H01S5/02469; H01S5/320225; H01S5/323; H01S5/32308; H01S5/32341
Claims Analysis
Total Claims: 40
Claim 1
Independent Claim
49 words
A structure comprising: a substrate including at least one upstanding mesa, each mesa having a top surface; and a group III-V nitride epitaxial film on the top surface of at least one mesa; wherein the at least one mesa including surfaces oriented along crack planes of the epitaxial film.
Claim 2
Dependent Claim
49 words
A structure comprising: a substrate including at least one upstanding mesa, each mesa having a top surface; and a group III-V nitride epitaxial film on the top surface of at least one mesa; wherein the at least one mesa including surfaces oriented along crack planes of the epitaxial film.
Claim 3
Dependent Claim
63 words
The structure of claim 1, wherein: the substrate is a sapphire substrate; each of the mesas is disposed on a c-plane of the sapphire substrate; the epitaxial film includes GaN; the top surface of each mesa has a width of less than about 10 microns; and each mesa further includes side surfaces and end surfaces oriented along m-planes of the GaN epitaxial film.
Claim 4
Dependent Claim
24 words
The structure of claim 2, wherein the top surface of each mesa has a width of from about 2 microns to about 4 microns.
Claim 5
Dependent Claim
21 words
The structure of claim 2, wherein the top surface of each mesa has a length of less than about 10 microns.
Claim 6
Dependent Claim
61 words
The structure of claim 1, wherein: the substrate is a sapphire substrate; each mesa is disposed on an a-plane of the sapphire substrate; the epitaxial film includes GaN; the top surface of each mesa has a width of less than about 10 microns; and each mesa further includes side surfaces and end surfaces oriented along m-planes of the GaN epitaxial film.
Claim 7
Dependent Claim
24 words
The structure of claim 5, wherein the top surface of each mesa has a width of from about 2 microns to about 4 microns.
Claim 8
Dependent Claim
21 words
The structure of claim 5, wherein the top surface of each mesa has a length of less than about 10 microns.
Claim 9
Dependent Claim
29 words
The structure of claim 1, wherein the at least one mesa comprises a plurality of mesas spaced from each other by a distance of more than about 4 microns.
Claim 10
Dependent Claim
29 words
The structure of claim 1, wherein the at least one mesa comprises a plurality of mesas spaced from each other by a distance of less than about 50 microns.
Claim 11
Dependent Claim
28 words
The structure of claim 1, wherein: the substrate includes a thinned membrane; and at least one mesa of the at least one mesa is disposed on the membrane.
Claim 12
Dependent Claim
39 words
The structure of claim 1, wherein the epitaxial film comprises GaN, and the structure further comprises an AlGaN epitaxial film formed on the GaN epitaxial film, the AlGaN epitaxial film having an aluminum concentration of up to about 18%.
Claim 13
Dependent Claim
33 words
A structure comprising: a substrate; and a patterned group III-V nitride film formed on the substrate, the group III-V nitride film including at least one upstanding mesa, each mesa having a top surface.
Claim 14
Dependent Claim
33 words
A structure comprising: a substrate; and a patterned group III-V nitride film formed on the substrate, the group III-V nitride film including at least one upstanding mesa, each mesa having a top surface.
Claim 15
Dependent Claim
46 words
The structure of claim 12, wherein the group III-V nitride film is comprised of GaN, the top surfaces of the mesas have a width of less than about 10 microns, and the mesas further include side surfaces and end surfaces oriented along m-planes of the GaN.
Claim 16
Dependent Claim
21 words
The structure of claim 13, wherein the top surfaces of the mesas have a width of less than about 4 microns.
Claim 17
Dependent Claim
21 words
The structure of claim 13, wherein the top surfaces of the mesas have a length of less than about 10 microns.
Claim 18
Dependent Claim
25 words
The structure of claim 12, wherein the mesas are spaced from each other by a distance of from about 4 microns to about 50 microns.
Claim 19
Dependent Claim
26 words
The structure of claim 12, wherein the substrate is a sapphire substrate having a continuous planar surface on which the group III-V nitride film is disposed.
Claim 20
Dependent Claim
41 words
The structure of claim 12, wherein the substrate includes at least one upstanding mesa, the mesas on the substrate each having a top surface, and the group III-V nitride film mesas are disposed on the top surfaces of the substrate mesas.
Claim 21
Dependent Claim
22 words
The structure of claim 18, wherein the top surfaces of the substrate mesas have a width of less than about 10 microns.
Claim 22
Dependent Claim
22 words
The structure of claim 18, wherein the top surfaces of the substrate mesas have a width of less than about 4 microns.
Claim 23
Dependent Claim
22 words
The structure of claim 12, wherein the substrate includes a thinned membrane, and at least one mesa is disposed on the membrane.
Claim 24
Dependent Claim
34 words
The structure of claim 12, wherein the epitaxial film is comprised of GaN, and the structure further comprises a AlGaN epitaxial film having an aluminum concentration of up to about 18% on the GaN.
Claim 25
Independent Claim
58 words
A method of forming a structure, comprising: providing a substrate; and patterning the substrate to form at least one mesa, each mesa including a top surface; epitaxially growing a group III-V nitride epitaxial film on the top surface of at least one mesa the at least one mesa including surfaces oriented along crack planes of the epitaxial film.
Claim 26
Independent Claim
58 words
A method of forming a structure, comprising: providing a substrate; and patterning the substrate to form at least one mesa, each mesa including a top surface; epitaxially growing a group III-V nitride epitaxial film on the top surface of at least one mesa the at least one mesa including surfaces oriented along crack planes of the epitaxial film.
Claim 27
Dependent Claim
18 words
The method of claim 23, wherein patterning the at least one mesa comprises reactive ion etching the substrate.
Claim 28
Dependent Claim
20 words
The method of claim 23, wherein patterning the at least one mesa comprises ablating the substrate using an excimer laser.
Claim 29
Dependent Claim
47 words
The method of claim 23, wherein: the group III-V nitride film comprises a GaN film; the top surface of each mesa has a width of less than about 10 microns; and each mesa further includes side surfaces and end surfaces oriented along m-planes of the GaN film.
Claim 30
Dependent Claim
28 words
The method of claim 26, wherein the substrate comprises sapphire and the at least one mesa is formed on a c-plane or an a-plane of the sapphire substrate.
Claim 31
Dependent Claim
29 words
The method of claim 23, further comprising: thinning the substrate to form a membrane; and forming at least one mesa of the at least one mesa on the membrane.
Claim 32
Dependent Claim
34 words
The method of claim 23, wherein the group III-V nitride film comprises GaN, and further comprising forming an AlGaN epitaxial film having an aluminum concentration of up to about 18% on the GaN film.
Claim 33
Independent Claim
85 words
A method of forming a structure, comprising the steps of: providing a sapphire substrate; forming a GaN film on the sapphire substrate; forming a plurality of upstanding mesas in the GaN film, each mesa including a top surface, opposed side surfaces and opposed end surfaces; wherein the top surfaces of the at least one mesa have a width of less than about 10 microns, and the side surfaces and end surfaces of the at least one mesa are oriented along m-planes of the GaN film.
Claim 34
Independent Claim
85 words
A method of forming a structure, comprising the steps of: providing a sapphire substrate; forming a GaN film on the sapphire substrate; forming a plurality of upstanding mesas in the GaN film, each mesa including a top surface, opposed side surfaces and opposed end surfaces; wherein the top surfaces of the at least one mesa have a width of less than about 10 microns, and the side surfaces and end surfaces of the at least one mesa are oriented along m-planes of the GaN film.
Claim 35
Dependent Claim
21 words
The method of claim 30, wherein the GaN film is formed on an a-plane or a c-plane of the sapphire substrate.
Claim 36
Dependent Claim
20 words
The method of claim 30, wherein the GaN film is formed on a continuous planar surface of the sapphire substrate.
Claim 37
Dependent Claim
64 words
The method of claim 30, further comprising prior to forming the GaN film on the sapphire substrate: forming a plurality of mesas on the sapphire substrate, each mesa of the sapphire substrate including a top surface; and wherein the epitaxial thin film of GaN is formed on the top surface of at least one of the plurality of the mesas of the sapphire substrate.
Claim 38
Dependent Claim
29 words
The method of claim 33, wherein the top surfaces of the plurality of the mesas on the sapphire substrate each have a width of less than about 10 microns.
Claim 39
Dependent Claim
33 words
The method of claim 30, further comprising thinning the sapphire substrate to form a membrane, and forming at least one of the plurality of the mesas in the GaN film on the membrane.
Claim 40
Dependent Claim
25 words
The method of claim 30, further comprising forming a AlGaN epitaxial film having an aluminum concentration of up to about 18% on the GaN film.
References Cited (Backward Citations)
US5614435A
Cited
US5874747A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2003-12-19 | 2004-06-19 | 2004-12-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2007-12-19 | 2008-06-19 | 2008-12-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2011-12-19 | 2012-06-19 | 2012-12-19 | $7700.00 | Window Closed / Lapsed |