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US5504039A
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Method for making a self-aligned oxide gate cap
Assignee: Apple Inc
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Filing: 1994-07-29
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Granted: 1996-04-02
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Expires: 2014-07-29
Abstract
Abstract A method for making a self-aligned oxide gate cap is provided. The method requires only one photoresist step to make a self-aligned oxide cap that can serve as an implant block and provide self-aligned contacts. A substrate with a gate line is provided. A first oxide layer (36) is then isotropically deposited over the gate line. A portion of the first oxide layer (36) is then etched anisotropically. A second oxide layer (40) is then isotropically deposited over the gate line and the remaining first oxide layer (36). A spacer mask (43) is then formed over the gate line. If preferred, the spacer mask (43) could be extended beyond the spacer region to further separate the drain region from the gate line with dielectric creating a lightly doped drain region. The exposed oxide layer is etched anisotropically, resulting in a dual-step spacer (44) that can act as an implant mask for the source and drain regions and as a self aligned ohmic contact area. The gate metal is completely protected by this dual-step spacer (44).
Inventors
- 👤 Gordon Grivna
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 22:22
CPC Classifications
H; H10; H10D; H10D62/00; H10D62/10; H10D62/13; H10D62/149; H10D62/151; H10D30/00; H10D30/01; H10D30/061; H10D30/0612; H10D30/0616; H10D30/60; H10D30/601; H10D30/603
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
93 words
A method for insulating a gate line comprising the steps of: a) providing a substrate having a gate line; b) forming a first dielectric layer around the gate line; c) anisotropically etching a portion of the first dielectric layer; d) depositing a second dielectric layer over the gate line; e) forming a spacer mask over a portion of the second dielectric layer; f) anisotropically etching a portion of the second dielectric layer thereby forming a spacer at the gate line; and g) forming a source and drain region self aligned to the spacer.
Claim 2
Independent Claim
93 words
A method for insulating a gate line comprising the steps of: a) providing a substrate having a gate line; b) forming a first dielectric layer around the gate line; c) anisotropically etching a portion of the first dielectric layer; d) depositing a second dielectric layer over the gate line; e) forming a spacer mask over a portion of the second dielectric layer; f) anisotropically etching a portion of the second dielectric layer thereby forming a spacer at the gate line; and g) forming a source and drain region self aligned to the spacer.
Claim 3
Dependent Claim
27 words
The method as in claim 1 where the first dielectric layer comprises a first oxide layer and wherein the second dielectric layer comprises a second oxide layer.
Claim 4
Dependent Claim
49 words
The method as in claim 2 wherein the gate line has a top surface and wherein the step of anisotropically etching a portion of the first dielectric layer comprises anisotropically etching the first dielectric layer until all the first dielectric layer is removed from the gate line top surface.
Claim 5
Dependent Claim
56 words
The method as in claim 1 wherein the spacer mask defines a dielectric opening and is formed by an exposure tool having an aligment tolerance and the step of forming a spacer mask comprises aligning a mask that is smaller than a desired dielectric opening by a dimension approximately equal to the exposure tool alignment tolerance.
Claim 6
Dependent Claim
24 words
The method as in claim 1 wherein forming the source and drain region further comprises the step of implanting the source and drain region.
Claim 7
Dependent Claim
16 words
The method as in claim 4 further comprising the step of depositing an ohmic metal layer.
Claim 8
Dependent Claim
15 words
The method as in claim 1 wherein the spacer formed completely envelops the gate line.
Claim 9
Dependent Claim
40 words
The method as in claim 1 wherein the spacer mask formed extends over a side of the gate line and wherein the steps of forming a spacer and forming the source and drain region form a lightly doped drain region.
Claim 10
Independent Claim
146 words
A method for insulating a gate line, comprising the steps of: a) providing a gallium arsenide substrate having a barrier layer and a gate line, the gate line having a top surface; b) forming an implant to lower access resistance near the gate line; c) forming a first oxide layer around the gate line; d) anisotropically etching a portion of the first oxide layer, leaving a portion of the first oxide layer at the gate line; e) depositing a second oxide layer over the gate line; f) forming a spacer mask over a portion of the second oxide layer; g) anisotropically etching a portion of the second oxide layer thereby forming a spacer at the gate line; h) implanting a source and drain region in the gallium arsenide substrate self aligned to the spacer; and i) depositing an ohmic metal layer on the gallium arsenide substrate.
Claim 11
Independent Claim
146 words
A method for insulating a gate line, comprising the steps of: a) providing a gallium arsenide substrate having a barrier layer and a gate line, the gate line having a top surface; b) forming an implant to lower access resistance near the gate line; c) forming a first oxide layer around the gate line; d) anisotropically etching a portion of the first oxide layer, leaving a portion of the first oxide layer at the gate line; e) depositing a second oxide layer over the gate line; f) forming a spacer mask over a portion of the second oxide layer; g) anisotropically etching a portion of the second oxide layer thereby forming a spacer at the gate line; h) implanting a source and drain region in the gallium arsenide substrate self aligned to the spacer; and i) depositing an ohmic metal layer on the gallium arsenide substrate.
Claim 12
Dependent Claim
14 words
The method as in claim 9 wherein the barrier layer comprises a nitride layer.
Claim 13
Dependent Claim
25 words
The method as in claim 9 further comprising the step of removing a portion of the barrier layer after implanting the source and drain region.
Claim 14
Dependent Claim
27 words
The method as in claim 9 further comprising the step of removing a portion of the barrier layer after anisotropically etching a portion of the first oxide.
Claim 15
Dependent Claim
54 words
The method as in claim 9 wherein the spacer mask defines a dielectric opening and is formed by an exposure tool and the step of forming a spacer mask comprises aligning a mask that is smaller than a desired dielectric opening by a dimension approximately equal to the alignment tolerance of the exposure tool.
Claim 16
Dependent Claim
15 words
The method as in claim 9 wherein the spacer formed completely envelopes the gate line.
Claim 17
Dependent Claim
38 words
The method as in claim 9 wherein the spacer mask formed extends over a side of the gate line and wherein the steps of forming a spacer and implanting a drain region form a lightly doped drain region.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-04-02 | 1999-10-02 | 2000-04-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-04-02 | 2003-10-02 | 2004-04-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-04-02 | 2007-10-02 | 2008-04-02 | $7700.00 | Window Closed / Lapsed |