Patent US4479850A successfully refreshed from Google Patents.
US4479850A
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Method for etching integrated semiconductor circuits containing double layers consisting of polysilicon and metal silicide
Assignee: Siemens AG
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Filing: 1984-02-17
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Granted: 1984-10-30
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Expires: 2004-02-17
Abstract
Abstract A method for etching a double layer semiconductor structure containing metal silicide layers or a metal silicide-polysilicon layer on a silicon substrate through a photoresist mask by means of reactive ion etching wherein dissociation and ionization of reactant gases take place in a plasma, the improvement which comprises: employing a mixture of chlorine gas and a highly reducing gas such as boron trichloride as the reactant gases.
Inventors
- 👤 Willy Beinvogl
- 👤 Barbara Hasler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 21:22
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/20; H10P50/26; H10P50/264; H10P50/266; H10P50/267; H10P50/268
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
64 words
In a method for etching a double layer semiconductor structure containing metal silicide layers or a metal silicide-polysilicon layer on a silicon substrate through a photoresist mask by means of reactive ion etching wherein dissociation and ionization of reactant gases take place in a plasma, the improvement which comprises: employing a mixture of chlorine gas and a highly reducing gas as the reactant gases.
Claim 2
Dependent Claim
64 words
In a method for etching a double layer semiconductor structure containing metal silicide layers or a metal silicide-polysilicon layer on a silicon substrate through a photoresist mask by means of reactive ion etching wherein dissociation and ionization of reactant gases take place in a plasma, the improvement which comprises: employing a mixture of chlorine gas and a highly reducing gas as the reactant gases.
Claim 3
Dependent Claim
15 words
A method as claimed in claim 1 wherein: said highly reducing gas is boron trichloride.
Claim 4
Dependent Claim
22 words
A method according to claim 2 wherein: the molecular ratio of boron trichloride to chlorine in said mixture is less than 1:2.
Claim 5
Dependent Claim
15 words
A method according to claim 1 wherein said mixture also contains an inert carrier gas.
Claim 6
Dependent Claim
13 words
A method according to claim 4 wherein said inert carrier gas is helium.
Claim 7
Dependent Claim
21 words
A method according to claim 4 wherein the molecular ratio of chlorine to boron trichloride to carrier gas is about 5:2:50.
Claim 8
Dependent Claim
18 words
A method according to claim 1 wherein said double layer consists of layers of tantalum silicide and polysilicon.
Claim 9
Dependent Claim
35 words
A method according to claim 7 wherein said tantalum silicide layer has a thickness of about 200 nm and said polysilicon layer consists of an n + -doped layer of about 300 nm in thickness.
Claim 10
Dependent Claim
51 words
A method according to claim 4 wherein said etching is carried out in two stages, utilizing the chlorine-boron trichloride-inert gas mixture in the first stage for about 1/5 of the total etching time and utilizing only a chlorine-inert gas mixture in a second stage for the balance of the etching time.
Claim 11
Dependent Claim
26 words
A method according to claim 1 wherein the gas pressure during etching is about 1.5 Pa and the power level is about 0.15 W/cm 2 .
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-10-30 | 1988-04-30 | 1988-10-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-10-30 | 1992-04-30 | 1992-10-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-10-30 | 1996-04-30 | 1996-10-30 | $7700.00 | Window Closed / Lapsed |