US7045404B2
Expired / Lapsed
US
⏱️ 0.0 years remaining
Nitride-based transistors with a protective layer and a low-damage recess and methods of fabrication thereof
Assignee: Wolfspeed Inc
•
Filing: 2004-01-16
•
Granted: 2006-05-16
•
Expires: 2024-01-16
Abstract
Abstract Transistors are fabricated by forming a nitride-based semiconductor barrier layer on a nitride-based semiconductor channel layer and forming a protective layer on a gate region of the nitride-based semiconductor barrier layer. Patterned ohmic contact metal regions are formed on the barrier layer and annealed to provide first and second ohmic contacts. The annealing is carried out with the protective layer on the gate region. A gate contact is also formed on the gate region of the barrier layer. Transistors having protective layer in the gate region are also provided as are transistors having a barrier layer with a sheet resistance substantially the same as an as-grown sheet resistance of the barrier layer.
Inventors
- 👤 Scott T. Sheppard
- 👤 Richard Peter Smith
- 👤 Zoltan Ring
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 18:50
CPC Classifications
H; H10; H10D; H10D30/00; H10D30/01; H10D30/015; H10P; H10P95/00; H10D30/40; H10D30/47; H10D30/471; H10D30/473; H10D30/4732; H10P10/00; H10D62/00; H10D62/80; H10D62/85; H10D62/8503
Claims Analysis
Total Claims: 54
Claim 1
Independent Claim
83 words
A method of fabricating a transistor, comprising; forming a nitride-based semiconductor barrier layer on a nitride-based semiconductor channel layer; forming a protective layer on a gate region of the nitride-based semiconductor barrier layer; forming patterned ohmic contact metal regions on the barrier layer; annealing the patterned ohmic contact metal to provide first and second ohmic contacts, wherein the annealing is carried out with the protective layer on the gate region; and forming a gate contact on the gate region of the barrier layer.
Claim 2
Independent Claim
83 words
A method of fabricating a transistor, comprising; forming a nitride-based semiconductor barrier layer on a nitride-based semiconductor channel layer; forming a protective layer on a gate region of the nitride-based semiconductor barrier layer; forming patterned ohmic contact metal regions on the barrier layer; annealing the patterned ohmic contact metal to provide first and second ohmic contacts, wherein the annealing is carried out with the protective layer on the gate region; and forming a gate contact on the gate region of the barrier layer.
Claim 3
Dependent Claim
20 words
The method of claim 1 , further comprising removing the protective layer subsequent to annealing the patterned ohmic contact metal.
Claim 4
Dependent Claim
15 words
The method of claim 2 , wherein the protective layer comprises an aluminum nitride layer.
Claim 5
Dependent Claim
22 words
The method of claim 2 , wherein removing the protective layer comprises removing the protective layer utilizing a low damage etching technique.
Claim 6
Dependent Claim
20 words
The method of claim 4 , wherein the low damage etching technique comprises a wet etch using a strong base.
Claim 7
Dependent Claim
25 words
The method of claim 2 , wherein removing the protective layer is followed by forming a passivation layer on exposed portions of the barrier layer.
Claim 8
Dependent Claim
49 words
The method of claim 6 , wherein forming a gate contact comprises: etching a recess in the passivation layer utilizing a low damage etch technique to expose a portion of the gate region of the barrier layer; and forming the gate contact in the recess in the passivation layer.
Claim 9
Dependent Claim
28 words
The method of claim 1 , wherein forming a gate contact comprises forming a gate contact on the protective layer on the gate region of the barrier layer.
Claim 10
Dependent Claim
23 words
The method of claim 1 , further comprising forming a passivation layer on exposed portions of the barrier layer and the protective layer.
Claim 11
Dependent Claim
31 words
The method of claim 9 , wherein forming a gate contact comprises forming a gate contact that extends through the passivation layer and the protective layer to contact the barrier layer.
Claim 12
Dependent Claim
94 words
The method of claim 1 , wherein forming a protective layer comprises forming a patterned protective layer on the barrier layer, the patterned protective layer covering a first portion of the barrier layer corresponding to the gate region and exposing adjacent second portions of the barrier layer corresponding to the first and second ohmic contacts; and wherein forming patterned ohmic contact metal regions comprises forming patterned ohmic contact metal regions on the second portions of the barrier layer, the patterned ohmic contact metal regions being adjacent and spaced apart from the patterned protective layer.
Claim 13
Dependent Claim
66 words
The method of claim 11 , wherein forming a patterned protective layer comprises: blanket depositing a protective layer material on the barrier layer; forming a mask on the blanket deposited protective layer material, the mask having windows corresponding to locations of the first and second ohmic contacts; etching the blanket deposited protective layer through the windows utilizing a low damage etching technique; and removing the mask.
Claim 14
Dependent Claim
31 words
The method of claim 12 , wherein the windows corresponding to locations of the first and second ohmic contacts are larger than an area of the first and second ohmic contacts.
Claim 15
Dependent Claim
45 words
The method of claim 12 , wherein forming patterned ohmic contact metal regions on the second portions of the barrier layer, the patterned ohmic contact metal regions being adjacent and spaced apart from the patterned protective layer is carried out prior to removing the mask.
Claim 16
Dependent Claim
40 words
The method of claim 11 , wherein forming a gate contact comprises: forming a recess in the patterned protective layer that exposes a portion of the first portion of the barrier layer; and forming a gate contact in the recess.
Claim 17
Dependent Claim
49 words
The method of claim 15 , wherein forming a recess comprises: forming a mask on the patterned protective layer, the mask having a window corresponding to a location of the recess; etching the patterned protective layer through the window utilizing a low damage etching technique; and removing the mask.
Claim 18
Dependent Claim
27 words
The method of claim 16 , wherein the low damage etching technique utilized to etch the patterned protective layer comprises a wet etch with a strong base.
Claim 19
Dependent Claim
42 words
The method of claim 15 , wherein forming a gate contact in the recess is followed by forming a passivation layer on the patterned protective layer and in a gap between the patterned protective layer and the first and second ohmic contacts.
Claim 20
Dependent Claim
12 words
The method of claim 11 , wherein the protective layer comprises SiN.
Claim 21
Dependent Claim
12 words
The method of claim 11 , wherein the protective layer comprises AlN.
Claim 22
Dependent Claim
14 words
The method of claim 11 , wherein the protective layer comprises SiO 2 .
Claim 23
Dependent Claim
36 words
The method of claim 11 , further comprising forming a passivation layer on the patterned protective layer and so as to substantially fill gaps between the patterned protective layer and the first and second ohmic contacts.
Claim 24
Dependent Claim
19 words
The method of claim 22 , wherein the patterned protective layer and the passivation layer comprise a same material.
Claim 25
Dependent Claim
21 words
The method of claim 22 , wherein the patterned protective layer comprises aluminum nitride and the passivation layer comprises silicon nitride.
Claim 26
Dependent Claim
24 words
The method of claim 11 , further comprising removing the patterned protective layer so as to expose the first portion of the barrier layer.
Claim 27
Dependent Claim
26 words
The meted of claim 25 , wherein removing the patterned protective layer is followed by forming a passivation layer on exposed portions of the barrier layer.
Claim 28
Dependent Claim
21 words
The method of claim 26 , wherein the patterned protective layer comprises aluminum nitride and the passivation layer comprises silicon nitride.
Claim 29
Dependent Claim
52 words
The method of claim 26 , wherein forming a gate contact is preceded by forming a passivation layer and wherein forming a gate contact comprises: forming a recess in the passivation layer that exposes a portion of the first portion of the barrier layer; and forming a gate contact in the recess.
Claim 30
Dependent Claim
46 words
The method of claim 28 , wherein forming a recess comprises: forming a mask on the passivation layer, the mask having a window corresponding to location of the recess; etching the passivation layer through the window utilizing a low damage etching technique; and removing the mask.
Claim 31
Dependent Claim
14 words
The method of claim 28 , wherein forming a passivation layer is performed in-situ.
Claim 32
Dependent Claim
19 words
The method of claim 30 , wherein forming the passivation layer comprises growing the passivation layer using MOCVD growth.
Claim 33
Dependent Claim
57 words
The method of claim 11 , wherein forming a gate contact is preceded by forming a passivation layer and wherein forming a gate contact comprises: forming a recess in the passivation layer and the patterned protective layer that exposes a portion of the first portion of the barrier layer; and forming a gate contact in the recess.
Claim 34
Dependent Claim
14 words
The method of claim 32 , wherein forming a passivation layer is performed in-situ.
Claim 35
Dependent Claim
19 words
The method of claim 33 , wherein forming the passivation layer comprises growing the passivation layer using MOCVD growth.
Claim 36
Dependent Claim
36 words
The method of claim 11 , wherein the protective layer is formed to a thickness of at least about a thickness of the ohmic contact material and wherein the gate is directly on the protective layer.
Claim 37
Dependent Claim
33 words
The method of claim 1 , further comprising forming a Group III-nitride layer to provide the nitride-based channel layer; and wherein forming a nitride-based semiconductor barrier layer comprises forming a Group III-nitride layer.
Claim 38
Dependent Claim
38 words
The method of claim 36 , wherein the channel layer has a composition of Al x Ga 1-x N wherein 0≦x<1, and wherein the bandgap of the channel layer is less than the bandgap of the barrier layer.
Claim 39
Dependent Claim
46 words
The method of claim 37 ; wherein the channel layer comprises aluminum gallium nitride (AlGaN), gallium nitride (GaN), indium gallium nitride (InGaN), and/or aluminum indium gallium nitride (AlInGaN); and wherein the barrier layer comprises aluminum nitride (AlN), aluminum indium nitride (AlInN), AlGaN, GaN, InGaN, and/or AlInGaN.
Claim 40
Dependent Claim
13 words
The method of claim 1 , wherein the barrier layer comprises multiple layers.
Claim 41
Dependent Claim
31 words
The method of claim 1 further comprising: forming a buffer layer on a substrate; and forming a Group III-nitride channel layer on the buffer layer to provide the nitride-based channel layer.
Claim 42
Dependent Claim
24 words
The method of claim 1 , where the channel layer and the barrier layer are configured to provide a High Electron Mobility Transistor (HEMT).
Claim 43
Dependent Claim
17 words
The method of claim 1 , wherein the nitride-based channel layer is provided on a SiC substrate.
Claim 44
Dependent Claim
19 words
The method of claim 1 , wherein the protective layer has a thickness of at least about two monolayers.
Claim 45
Dependent Claim
22 words
The method of claim 1 , wherein the protective layer has a thickness of from about 5 nm to about 500 nm.
Claim 46
Independent Claim
101 words
A method of fabricating a transistor, comprising: forming a nitride-based semiconductor barrier layer on a nitride-based semiconductor channel layer; forming a protective layer on a gate region of the nitride-based semiconductor barrier layer; forming patterned ohmic contact metal regions on the barrier layer; annealing the patterned ohmic contact metal to provide first and second ohmic contacts; etching a recess in the protective layer in a gate region of the barrier layer utilizing a low damage etch technique to expose a portion of the gate region of the barrier layer; and forming the gate contact in the recess in the protective layer.
Claim 47
Independent Claim
101 words
A method of fabricating a transistor, comprising: forming a nitride-based semiconductor barrier layer on a nitride-based semiconductor channel layer; forming a protective layer on a gate region of the nitride-based semiconductor barrier layer; forming patterned ohmic contact metal regions on the barrier layer; annealing the patterned ohmic contact metal to provide first and second ohmic contacts; etching a recess in the protective layer in a gate region of the barrier layer utilizing a low damage etch technique to expose a portion of the gate region of the barrier layer; and forming the gate contact in the recess in the protective layer.
Claim 48
Dependent Claim
14 words
The method of claim 45 , wherein the protective layer comprises a passivation layer.
Claim 49
Dependent Claim
14 words
The method of claim 46 , wherein forming a protective layer is performed in-situ.
Claim 50
Dependent Claim
19 words
The method of claim 47 , wherein forming the protective layer comprises growing the protective layer using MOCVD growth.
Claim 51
Dependent Claim
24 words
The method of claim 45 , wherein the protective layer comprises an aluminum nitride layer, a silicon nitride layer and/or a silicon dioxide layer.
Claim 52
Dependent Claim
20 words
The method of claim 45 , wherein the low damage etching technique comprises a wet etch using a strong base.
Claim 53
Dependent Claim
29 words
The method of claim 45 , wherein annealing the patterned ohmic contact metal to provide first and second ohmic contacts is carried out prior to forming a protective layer.
Claim 54
Dependent Claim
29 words
The method of claim 45 , wherein annealing the patterned ohmic contact metal to provide first and second ohmic contacts is carried out subsequent to forming a protective layer.
References Cited (Backward Citations)
US4471366A
Cited
US4424525A
Cited
US4727403A
Cited
US4755867A
Cited
US4788156A
Cited
EP0334006A1
Cited
US4946547A
Cited
US5053348A
Cited
US5210051A
Cited
US5172197A
Cited
US5292501A
Cited
US5200022A
Cited
US5192987A
Cited
US5296395A
Cited
US5389571A
Cited
US5705827A
Cited
EP0563847A2
Cited
WO1993023877A1
Cited
US5298445A
Cited
US5701019A
Cited
US5393993A
Cited
US5686737A
Cited
US5523589A
Cited
US5592501A
Cited
US5700714A
Cited
US5534462A
Cited
US6046464A
Cited
US5804482A
Cited
US5885860A
Cited
US5796127A
Cited
US5946547A
Cited
US5990531A
Cited
US6028328A
Cited
JPH1050982A
Cited
US20030123829A1
Cited
US20040004223A1
Cited
US6025613A
Cited
US6448648B1
Cited
US6064082A
Cited
US5900641A
Cited
US6242327B1
Cited
US20020008241A1
Cited
US6177685B1
Cited
US6150680A
Cited
JPH11261053A
Cited
US6086673A
Cited
US6316793B1
Cited
US6429467B1
Cited
US20030145784A1
Cited
US6218680B1
Cited
US20010015446A1
Cited
US6639255B2
Cited
JP2001230407A
Cited
US20010020700A1
Cited
US20010023964A1
Cited
US6586781B2
Cited
WO2001057929A1
Cited
US20010040246A1
Cited
US20040241970A1
Cited
US20020017696A1
Cited
US6492669B2
Cited
JP2002016087A
Cited
US6515316B1
Cited
US20020066908A1
Cited
US20030157776A1
Cited
US6548333B2
Cited
US20020079508A1
Cited
US6429468B1
Cited
US20020119610A1
Cited
US20020167023A1
Cited
US20030017683A1
Cited
US20030020092A1
Cited
US20030102482A1
Cited
WO2003049193A1
Cited
US20030213975A1
Cited
US6852615B2
Cited
US20040061129A1
Cited
WO2004008495A2
Cited
US20040021152A1
Cited
US20040029330A1
Cited
JP2004342810A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2009-05-15 | 2009-11-14 | 2010-05-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2013-05-15 | 2013-11-14 | 2014-05-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2017-05-15 | 2017-11-14 | 2018-05-16 | $7700.00 | Window Closed / Lapsed |