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US4214946A Expired / Lapsed US ⏱️ 0.0 years remaining

Selective reactive ion etching of polysilicon against SiO2 utilizing SF6 -Cl2 -inert gas etchant

Assignee: International Business Machines Corp
•
Filing: 1979-02-21
•
Granted: 1980-07-29
•
Expires: 1999-02-21
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Abstract

Abstract Disclosed is an improved Reactive Ion Etch (RIE) technique for etching polysilicon or single crystal silicon as must be done in Very Large Scale Integration (VLSI) using silicon technology. It teaches the use of an etch gas that consists of a mixture of sulfur hexafluoride (SF 6 ) and chlorine (Cl 2 ) diluted with inert gas. This etch gas allows an RIE process which combines the very desirable features of selectivity (high Si/SiO 2 etch rate ratio) and directionality which creates vertical side walls on the etched features. Vertical side walls mean no mask undercutting, hence zero etch bias. It is particularly applicable to device processing in which micron or sub-micron sized lines must be fabricated to extremely close tolerances. It is a distinct improvement over wet chemical etching or plasma etching as it is conventionally applied.

Inventors

  • 👤 Lawrence E. Forget
  • 👤 Robert A. Gdula
  • 👤 Joseph C. Hollis

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-24 19:41
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/20; H10P50/24; H10P50/242; Y; Y10; Y10S; Y10S148/00; Y10S148/131

Claims Analysis

Total Claims: 6
Claim 1
Independent Claim 69 words
An improved technique of selective reactive ion etching of polysilicon against silicon dioxide, said technique being characterized by the employment of a plasma derived from a gas mixture consisting essentially of x parts of SF 6 , y parts of Cl 2 , and z parts of inert gas and wherein x+y+z is essentially one hundred, x+y is approximately ten, and x and y are respectively greater than zero.
Claim 2
Dependent Claim 69 words
An improved technique of selective reactive ion etching of polysilicon against silicon dioxide, said technique being characterized by the employment of a plasma derived from a gas mixture consisting essentially of x parts of SF 6 , y parts of Cl 2 , and z parts of inert gas and wherein x+y+z is essentially one hundred, x+y is approximately ten, and x and y are respectively greater than zero.
Claim 3
Dependent Claim 33 words
An improved technique of selective reactive ion etching of polysilicon against silicon dioxide, as recited in claim 1 further characterized in that x has a magnitude in the order of one to nine.
Claim 4
Dependent Claim 45 words
An improved technique of selective reactive ion etching of polysilicon against silicon dioxide, as recited in claim 1 wherein x has a magnitude of approximately two and one-half, y has a magnitude of approximately seven and one-half, and z has a value of approximately ninety.
Claim 5
Dependent Claim 33 words
An improved technique of selective reactive ion etching of polysilicon against silicon dioxide, as recited in any one of the claims 1, 2 or 3, further characterized that the inert gas is helium.
Claim 6
Dependent Claim 33 words
An improved technique of selective reactive ion etching of polysilicon against silicon dioxide, as recited in any one of the claims 1, 2 or 3, further characterized that the inert gas is argon.

References Cited (Backward Citations)

US3615956A Cited
US4104090A Cited
US4104086A Cited
US4159915A Cited
US4157269A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1983-07-29 1984-01-28 1984-07-29 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1987-07-29 1988-01-28 1988-07-29 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1991-07-29 1992-01-28 1992-07-29 $7700.00 Window Closed / Lapsed

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