Patent US4726879A successfully refreshed from Google Patents.
US4726879A
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RIE process for etching silicon isolation trenches and polycides with vertical surfaces
Assignee: International Business Machines Corp
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Filing: 1986-09-08
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Granted: 1988-02-23
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Expires: 2006-09-08
Abstract
Abstract Disclosed is a process for etching semiconductor materials with a high etch rate against an insulator mask using a novel etchant gas mixture. The mixture consists of a chlorocarbon (e.g., CCl 2 F 2 , CCl 4 or CCl 3 F), SF 6 , O 2 and an inert gas (e.g. He). The preferred gas mixture contains 2/1 ratio of the chlorocarbon to SF6 and the following composition: 1-4% of SF 6 , 3-10% of O 2 , 74-93% of He and 3-10% of chlorocarbon. The etch rate of silicon (or silicide) against an oxide mask using this etchant gas mixture under normal etching conditions is high, on the order of 30-40. An impressive feature of the process is shape control of trenches by mere manipulation of the RIE system power.
Inventors
- 👤 James A. Bondur
- 👤 Nicholas J. Giammarco
- 👤 Thomas A. Hansen
- 👤 George A. Kaplita
- 👤 John S. Lechaton
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 15:24
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/69; H10P50/691; H10P50/693; H10P50/694; H10P50/20; H10P50/24; H10P50/242; H10P50/26; H10P50/264; H10P50/266; H10P50/267; H10P50/268
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
59 words
A method for anisotropic etching of a semiconductor material comprising: providing a semiconductor material having an inorganic material mask thereon; and subjecting said material to a plasma consisting of w percent inert gas, x percent chlorocarbon, y percent SF 6 and z percent O 2 wherein w+x+y+z is 100% and each of said w,x,y and z percentages exceeds 0%.
Claim 2
Independent Claim
59 words
A method for anisotropic etching of a semiconductor material comprising: providing a semiconductor material having an inorganic material mask thereon; and subjecting said material to a plasma consisting of w percent inert gas, x percent chlorocarbon, y percent SF 6 and z percent O 2 wherein w+x+y+z is 100% and each of said w,x,y and z percentages exceeds 0%.
Claim 3
Dependent Claim
12 words
The method as recited in claim 1 wherein x is approximately 2y.
Claim 4
Dependent Claim
32 words
The method as recited in claim 1 wherein said chlorocarbon is selected from the group consisting of CCl 2 F 2 , CCl 4 , CCl 3 F and CClF 3 .
Claim 5
Dependent Claim
13 words
The method as recited in claim 1 wherein said inert gas is helium.
Claim 6
Dependent Claim
16 words
The method as recited in claim 4 wherein said chlorocarbon is CCl 2 F 2 .
Claim 7
Dependent Claim
12 words
The method as recited in claim 5 wherein said material is silicon.
Claim 8
Dependent Claim
25 words
The method as recited in claim 6 wherein w is approximately 74-93%, x is approximately 3-10%, y is approximately 1-4% and z is approximately 3-10%.
Claim 9
Dependent Claim
25 words
The method as recited in claim 6 wherein said mask material is selected from a group consisting of silicon dioxide, silicon nitride and aluminum oxide.
Claim 10
Dependent Claim
12 words
The method as recited in claim 5 wherein said material is polycide.
Claim 11
Independent Claim
82 words
A method of forming trenches in a semiconductor material comprising: providing a semiconductor material having an inorganic material mask thereon; and subjecting said material to an RF plasma consisting essentially of w percent of an inert gas, x percent of a chlorocarbon, y percent of SF 6 and z percent of O 2 where said w,x,y, and z is each greater than zero and w+x+y+z is essentially one hundred percent to etch the regions of said material not masked by said mask.
Claim 12
Independent Claim
82 words
A method of forming trenches in a semiconductor material comprising: providing a semiconductor material having an inorganic material mask thereon; and subjecting said material to an RF plasma consisting essentially of w percent of an inert gas, x percent of a chlorocarbon, y percent of SF 6 and z percent of O 2 where said w,x,y, and z is each greater than zero and w+x+y+z is essentially one hundred percent to etch the regions of said material not masked by said mask.
Claim 13
Dependent Claim
31 words
The method as recited in claim 10 wherein said chlorocarbon is selected from the group consisting of CCl 2 F 2 , CCl 3 F, CClF 3 and CCl 4 .
Claim 14
Dependent Claim
13 words
The method as recited in claim 10 wherein said inert gas is helium.
Claim 15
Dependent Claim
12 words
The method as recited in claim 10 wherein said material is silicon.
Claim 16
Dependent Claim
22 words
The method as recited in claim 13 wherein said inert gas is helium and said chlorocarbon is CCl 2 F 2 .
Claim 17
Dependent Claim
9 words
The method as recited in claim 14 wherein x=2y.
Claim 18
Dependent Claim
28 words
The method as recited in claim 15 wherein said mask is composed of silicon dioxide and the etch rate ratio of silicon to silicon dioxide is about 30-40:1.
Claim 19
Dependent Claim
22 words
The method as recited in claim 13 wherein said silicon material includes upper and lower regions of first and second conductivity types.
Claim 20
Dependent Claim
14 words
The method as recited in claim 10 wherein said trench has substantially vertical walls.
Claim 21
Dependent Claim
41 words
The method as recited in claim 18 including changing the shape of said trench from one having zero pitch to one having a positive pitch by decreasing the power density to below that used for etching said trench with zero pitch.
Claim 22
Dependent Claim
41 words
The method as recited in claim 18 including changing the shape of said trench from one having zero pitch to another having a negative pitch by increasing the power density to above that used for etching said trench with zero pitch.
Claim 23
Independent Claim
49 words
A method of patterning a metal silicide and polysilicon dual layer by anisotropic etching comprising: providing a metal silicide and polysilicon dual layer having an inorganic mask thereon; and subjecting said layer to a plasma composed of CCl 2 F 2 , He, O 2 and SF 6 .
Claim 24
Independent Claim
49 words
A method of patterning a metal silicide and polysilicon dual layer by anisotropic etching comprising: providing a metal silicide and polysilicon dual layer having an inorganic mask thereon; and subjecting said layer to a plasma composed of CCl 2 F 2 , He, O 2 and SF 6 .
Claim 25
Dependent Claim
33 words
The method as recited in claim 21 wherein said plasma is composed of approximately 3-10% of CCl 2 F 2 , 1-4% of SF 6 , 3-10% of O 2 and 74-93% He.
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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) | 1991-02-22 | 1991-08-24 | 1992-02-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-02-22 | 1995-08-24 | 1996-02-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-02-22 | 1999-08-24 | 2000-02-23 | $7700.00 | Window Closed / Lapsed |