US5346586A
Expired / Lapsed
US
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Method for selectively etching polysilicon to gate oxide using an insitu ozone photoresist strip
Assignee: Round Rock Research LLC
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Filing: 1992-12-23
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Granted: 1994-09-13
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Expires: 2012-12-23
Abstract
Abstract In semiconductor manufacture, a method of etching a polysilicon layer to a gate oxide in a semiconductor structure is provided. The method is performed insitu in a plasma etch chamber. Initially, an oxide hard mask is formed on the semiconductor structure by etching a deposited oxide layer through a photoresist mask. The photoresist mask is then stripped in the same etch chamber using a high pressure ozone plasma. With the photoresist mask stripped from the semiconductor structure, the polysilicon layer can be etched through the oxide hard mask to the gate oxide with a high etch selectivity.
Inventors
- 👤 David J. Keller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 17:52
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/20; H10P50/28; H10P50/286; H10P50/287; H10P50/26; H10P50/264; H10P50/266; H10P50/267; H10P50/268; H10P50/71
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
121 words
In semiconductor manufacture, a method for etching a silicide layer and a polysilicon layer to a gate oxide layer formed on a substrate, comprising: forming an oxide layer on the silicide layer; forming a patterned photoresist mask on the oxide layer; forming an oxide hard mask by etching the oxide layer through the photoresist mask in an etch chamber of a reactive ion etcher (RIE) using a first gas etchant; removing the photoresist mask insitu in the etch chamber using an ozone plasma; etching the silicide layer insitu in the etch chamber using the oxide hard mask and a second gas etchant; and etching the polysilicon layer insitu in the etch chamber using the oxide mask and a third gas etchant.
Claim 2
Dependent Claim
121 words
In semiconductor manufacture, a method for etching a silicide layer and a polysilicon layer to a gate oxide layer formed on a substrate, comprising: forming an oxide layer on the silicide layer; forming a patterned photoresist mask on the oxide layer; forming an oxide hard mask by etching the oxide layer through the photoresist mask in an etch chamber of a reactive ion etcher (RIE) using a first gas etchant; removing the photoresist mask insitu in the etch chamber using an ozone plasma; etching the silicide layer insitu in the etch chamber using the oxide hard mask and a second gas etchant; and etching the polysilicon layer insitu in the etch chamber using the oxide mask and a third gas etchant.
Claim 3
Dependent Claim
32 words
The method as claimed in claim 1 and wherein the first gas etchant includes a species of gas selected from the group of gas species consisting of fluorocarbon, chlorine or fluorine species.
Claim 4
Dependent Claim
17 words
The method as claimed in claim 1 and wherein the silicide layer is formed of tungsten silicide.
Claim 5
Dependent Claim
30 words
The method as claimed in claim 1 and wherein the third gas etchant includes a species selected from the group of species consisting of a fluorine, bromine, or chlorine species.
Claim 6
Dependent Claim
21 words
The method as claimed in claim 1 and wherein the second gas etchant includes SF 6 , Q 2 and He.
Claim 7
Dependent Claim
129 words
In a semiconductor structure including a substrate, a gate oxide layer formed on the substrate, a polysilicon layer formed on the gate oxide, and a silicide layer formed on the polysilicon layer, a method of etching the silicide and polysilicon layers, comprising: forming an oxide layer on the silicide layer; forming a photoresist mask on the oxide layer; etching the oxide layer through the photoresist mask in an etch chamber of a reactive ion etcher (RIE) using a first gas etchant to form an oxide hard mask; stripping the photoresist mask insitu in the etch chamber using an ozone plasma; etching the silicide layer insitu in the etch chamber using a second gas etchant; and etching the polysilicon layer insitu in the etch chamber using a third gas etchant.
Claim 8
Dependent Claim
129 words
In a semiconductor structure including a substrate, a gate oxide layer formed on the substrate, a polysilicon layer formed on the gate oxide, and a silicide layer formed on the polysilicon layer, a method of etching the silicide and polysilicon layers, comprising: forming an oxide layer on the silicide layer; forming a photoresist mask on the oxide layer; etching the oxide layer through the photoresist mask in an etch chamber of a reactive ion etcher (RIE) using a first gas etchant to form an oxide hard mask; stripping the photoresist mask insitu in the etch chamber using an ozone plasma; etching the silicide layer insitu in the etch chamber using a second gas etchant; and etching the polysilicon layer insitu in the etch chamber using a third gas etchant.
Claim 9
Dependent Claim
17 words
The method as recited in claim 6 and wherein the first gas etchant is a fluorocarbon gas.
Claim 10
Dependent Claim
20 words
The method as recited in claim 7 and wherein the first gas etchant includes CF 4 and CHF 3 .
Claim 11
Dependent Claim
15 words
The method as recited in claim 6 and wherein the silicide layer is tungsten silicide.
Claim 12
Dependent Claim
18 words
The method as recited in claim 6 and wherein the second gas etchant includes SF 6 and He.
Claim 13
Dependent Claim
19 words
The method as recited in claim 6 and wherein the third gas etchant includes Hbr and Cl 2 .
Claim 14
Dependent Claim
126 words
In a semiconductor structure including a silicon substrate, a gate oxide, a polysilicon layer and a silicide layer, a method for etching the polysilicon layer to the gate oxide, comprising; forming an oxide hard mask by depositing an oxide layer on the silicide layer, forming a photoresist mask on the oxide layer and etching the oxide layer in an etch chamber of a reactive ion etcher (RIE) using a first etching gas; stripping the photoresist mask insitu in the etch chamber using an ozone plasma; etching the silicide layer in the etch chamber using the oxide hard mask and a second etch gas; and etching the polysilicon layer to the gate oxide in the etch chamber using the oxide hard mask and a third etch gas.
Claim 15
Dependent Claim
126 words
In a semiconductor structure including a silicon substrate, a gate oxide, a polysilicon layer and a silicide layer, a method for etching the polysilicon layer to the gate oxide, comprising; forming an oxide hard mask by depositing an oxide layer on the silicide layer, forming a photoresist mask on the oxide layer and etching the oxide layer in an etch chamber of a reactive ion etcher (RIE) using a first etching gas; stripping the photoresist mask insitu in the etch chamber using an ozone plasma; etching the silicide layer in the etch chamber using the oxide hard mask and a second etch gas; and etching the polysilicon layer to the gate oxide in the etch chamber using the oxide hard mask and a third etch gas.
Claim 16
Dependent Claim
32 words
The method as recited in claim 12 and wherein the second etch gas contains a gas species selected from the group of species consisting of a fluorine, chlorine or bromine gas species.
Claim 17
Dependent Claim
19 words
The method as recited in claim 12 and wherein the third etch gas contains HBr and Cl 2 .
Claim 18
Dependent Claim
18 words
The method as recited in claim 12 and wherein the first etch gas contains a fluorocarbon gas species.
Claim 19
Dependent Claim
25 words
The method as recited in claim 12 and wherein the etch selectivity of the polysilicon to the gate oxide is about twenty eight to one.
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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) | 1997-09-12 | 1998-03-14 | 1998-09-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-09-12 | 2002-03-14 | 2002-09-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-09-12 | 2006-03-14 | 2006-09-13 | $7700.00 | Window Closed / Lapsed |