Patent US5587045A successfully refreshed from Google Patents.
US5587045A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Gettering of particles from an electro-negative plasma with insulating chuck
Assignee: International Business Machines Corp
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Filing: 1995-04-27
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Granted: 1996-12-24
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Expires: 2015-04-27
Abstract
Abstract Apparatus controls a wafer potential in a plasma system when the plasma is off to keep the wafer slightly negative at all times in order to reduce and eliminate the collection of charged particles on the wafer. The apparatus allows the wafer bias to be reduced to a small negative voltage and then holds that voltage. This greatly reduces the net positive flux to the wafer. A diode and a programmed power supply hold a minimum negative voltage on the back of the wafer electrode when the plasma density is decaying to zero.
Inventors
- 👤 John H. Keller
- 👤 Gregory Costrini
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 05:09
CPC Classifications
H; H01; H01J; H01J37/00; H01J37/32; H01J37/32009; H01J37/32082; H01J37/32174; H01J37/32431; H01J37/32623; H01J37/32697; H01J37/32706; H01J37/32917; H01J37/32935; H01J37/32963
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
115 words
In a plasma processing system used in the manufacture of semiconductor circuits wherein a semiconductor wafer is mounted on a negative electrode and exposed to a plasma discharge, said wafer being separated from said negative electrode by an insulator, an apparatus for preventing negatively charged particulates from going to the wafer when the plasma discharge is turned off, said apparatus comprising: a sensing device connected to said negative electrode through a diode and a choke; a source of voltage between said sensing device and circuit ground; and bias control means connected across said capacitor for controlling said source of voltage to maintain a small negative bias on said wafer when plasma density decays to zero.
Claim 2
Dependent Claim
115 words
In a plasma processing system used in the manufacture of semiconductor circuits wherein a semiconductor wafer is mounted on a negative electrode and exposed to a plasma discharge, said wafer being separated from said negative electrode by an insulator, an apparatus for preventing negatively charged particulates from going to the wafer when the plasma discharge is turned off, said apparatus comprising: a sensing device connected to said negative electrode through a diode and a choke; a source of voltage between said sensing device and circuit ground; and bias control means connected across said capacitor for controlling said source of voltage to maintain a small negative bias on said wafer when plasma density decays to zero.
Claim 3
Dependent Claim
13 words
The apparatus recited in claim 1 wherein said sensing device is a capacitor.
Claim 4
Dependent Claim
34 words
The apparatus recited in claim 1 wherein said bias control means is an operational amplifier having inputs connected across said sensing device and generating an output control voltage to control said source of voltage.
Claim 5
Dependent Claim
45 words
The apparatus recited in claim 1 wherein said bias control means is a high voltage operational amplifier having inputs connected across said sensing device and generating an output voltage, said output voltage being said source of voltage connected between said sensing device and circuit ground.
Claim 6
Dependent Claim
39 words
The apparatus recited in claim 1 wherein said sensing device is a capacitor and said bias control means is an operational amplifier connected across said capacitor, said operational amplifier generating a control voltage for controlling said source of voltage.
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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) | 1999-12-24 | 2000-06-24 | 2000-12-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-12-24 | 2004-06-24 | 2004-12-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-12-24 | 2008-06-24 | 2008-12-24 | $7700.00 | Window Closed / Lapsed |