US4248688A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ion milling of thin metal films
Assignee: International Business Machines Corp
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Filing: 1979-09-04
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Granted: 1981-02-03
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Expires: 1999-09-04
Abstract
Abstract Metals such as platinum and palladium are preferentially removed in the presence of their metal silicides by ion milling in a noble gas atmosphere such as argon. The process can be used on semiconductor chips to remove excess platinum after platinum silicide has been formed in the contact holes.
Inventors
- 👤 Helmut M. Gartner
- 👤 Steve I. Petvai
- 👤 Homi G. Sarkary
- 👤 Randolph H. Schnitzel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 08:35
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/20; H10P50/26; H10P50/262; Y; Y10; Y10S; Y10S148/00; Y10S148/143
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
83 words
A process for removing a metal in the presence of its silicide comprising ion milling the metal and the metal silicide in an atmosphere consisting essentially of a noble gas at a pressure range of from about 2-4×10 -4 torr with the angle of incidence of the ion milling on the metal being from about 15° to 45° from the vertical, whereby the metal is removed at a rate of at least about three times the rate of removal of the metal silicide.
Claim 2
Dependent Claim
83 words
A process for removing a metal in the presence of its silicide comprising ion milling the metal and the metal silicide in an atmosphere consisting essentially of a noble gas at a pressure range of from about 2-4×10 -4 torr with the angle of incidence of the ion milling on the metal being from about 15° to 45° from the vertical, whereby the metal is removed at a rate of at least about three times the rate of removal of the metal silicide.
Claim 3
Dependent Claim
12 words
The process of claim 1 wherein the atmosphere consists of argon gas.
Claim 4
Dependent Claim
13 words
The process of claim 1 wherein the angle of incidence is about 30°.
Claim 5
Dependent Claim
30 words
The process of claim 1 wherein the ion milling is at an acceleration voltage of from about 800-2,000 volts and the accelerator current of from about 70 to 90 milliamperes.
Claim 6
Dependent Claim
17 words
The process of claim 1 wherein the metal is platinum and the metal silicide is platinum silicide.
Claim 7
Dependent Claim
69 words
The process of claim 5 wherein the noble gas is argon, the angle of incidence of the ion beam is about 30°, the acceleration voltage is about 1000 volts and the acceleration current is from about 70 to 90 milliamperes whereby the platinum is removed at a rate of about 600 A per minute and the platinum silicide is removed at a rate of about 20-40 A per minute.
Claim 8
Dependent Claim
17 words
The process of claim 1 wherein the metal is palladium and the metal silicide is palladium silicide.
Claim 9
Dependent Claim
128 words
A process of removing a platinum layer from the surface of an insulating layer on a semiconductor substrate in the presence of a platinum silicide contact layer on the surface of said semiconductor substrate comprising ion milling the platinum and the platinum silicide in an atmosphere consisting essentially of a noble gas at a pressure of about 2-4×10 -4 torr with an ion beam whose angle of incidence on the platinum and platinum silicide layers is about 30° from the vertical at an acceleration voltage of about 1000 volts and an acceleration current of about 70 to 90 milliamperes whereby the platinum is removed at a rate of about 600 A per minute and the platinum silicide is removed at a rate of about 20-40 A per minute.
Claim 10
Dependent Claim
128 words
A process of removing a platinum layer from the surface of an insulating layer on a semiconductor substrate in the presence of a platinum silicide contact layer on the surface of said semiconductor substrate comprising ion milling the platinum and the platinum silicide in an atmosphere consisting essentially of a noble gas at a pressure of about 2-4×10 -4 torr with an ion beam whose angle of incidence on the platinum and platinum silicide layers is about 30° from the vertical at an acceleration voltage of about 1000 volts and an acceleration current of about 70 to 90 milliamperes whereby the platinum is removed at a rate of about 600 A per minute and the platinum silicide is removed at a rate of about 20-40 A per minute.
Claim 11
Dependent Claim
18 words
The process of claim 8 wherein the induced substrate temperature during the ion milling is below 200° C.
References Cited (Backward Citations)
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US3770606A
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US3642548A
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US3860783A
Cited
US3975252A
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US4135998A
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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) | 1984-02-03 | 1984-08-04 | 1985-02-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-02-03 | 1988-08-04 | 1989-02-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-02-03 | 1992-08-04 | 1993-02-03 | $7700.00 | Window Closed / Lapsed |