US5684669A
Expired / Lapsed
US
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Method for dechucking a workpiece from an electrostatic chuck
Assignee: Applied Materials Inc
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Filing: 1995-06-07
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Granted: 1997-11-04
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Expires: 2015-06-07
Abstract
Abstract A method of dechucking a workpiece from an electrostatic chuck. The method adaptively produces a dechucking voltage for canceling any unpredictable residual electrostatic fields between a workpiece and the electrostatic chuck. The method contains the steps of (a) applying a lifting force to the workpiece; (b) altering the chucking voltage; (c) measuring the lifting force; (d) comparing the measured lifting force to a threshold level; and, depending on the result of the comparison, either (e) maintaining the chucking voltage at its present level for a predefined period of time and physically dechucking the workpiece or (f) repeating steps (b), (c), (d) and (e).
Inventors
- 👤 Kenneth S. Collins
- 👤 Douglas Buchberger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 01:00
CPC Classifications
H; H10; H10P; H10P72/00; H10P72/70; H10P72/72; H02; H02N; H02N13/00; H10P72/722
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
95 words
A method of dechucking a workpiece from an electrostatic chuck comprising the steps of: (a) applying a pressurized gas lifting force to the workpiece; (b) altering a chucking voltage applied to said electrostatic chuck; (c) measuring the pressurized gas lifting force; (d) comparing the measured pressurized gas lifting force to a threshold level; (e) when the measured pressurized gas lifting force is less than the threshold level, maintaining the chucking voltage at a fixed magnitude for a predefined period of time and physically dechucking the workpiece; (f) otherwise, repeating steps (b), (c), (d), and (e).
Claim 2
Independent Claim
95 words
A method of dechucking a workpiece from an electrostatic chuck comprising the steps of: (a) applying a pressurized gas lifting force to the workpiece; (b) altering a chucking voltage applied to said electrostatic chuck; (c) measuring the pressurized gas lifting force; (d) comparing the measured pressurized gas lifting force to a threshold level; (e) when the measured pressurized gas lifting force is less than the threshold level, maintaining the chucking voltage at a fixed magnitude for a predefined period of time and physically dechucking the workpiece; (f) otherwise, repeating steps (b), (c), (d), and (e).
Claim 3
Dependent Claim
30 words
The method of claim 1 wherein said step of applying said pressurized gas lifting force further comprises the step of applying a heat transfer gas to a workpiece-to-electrostatic chuck interface.
Claim 4
Dependent Claim
31 words
The method of claim 2 wherein said measuring step further comprises the step of measuring a flow rate of the heat transfer gas as indicia of the pressurized gas lifting force.
Claim 5
Dependent Claim
30 words
The method of claim 2 wherein said measuring step further comprises the step of measuring a pressure of the heat transfer gas as indicia of the pressurized gas lifting force.
Claim 6
Dependent Claim
15 words
The method of claim 3 wherein said threshold level is a predefined flow rate level.
Claim 7
Dependent Claim
52 words
The method of claim 5 further comprising the steps of: comparing the measured flow rate to the predefined flow rate level; and when the measured flow rate exceeds the predefined flow rate level, maintaining the chucking voltage at a fixed magnitude for a predefined period of time and physically dechucking the workpiece.
Claim 8
Dependent Claim
14 words
The method of claim 4 wherein said threshold level is a predefined pressure level.
Claim 9
Dependent Claim
21 words
The method of claim 1 wherein said voltage altering step further comprises the step of changing a magnitude of said voltage.
Claim 10
Dependent Claim
21 words
The method of claim 1 wherein said voltage altering step further comprises the step of changing a polarity of said voltage.
Claim 11
Dependent Claim
38 words
The method of claim 1 wherein said voltage altering step further comprises the step of decrementing said voltage from a first voltage level toward a second voltage level, where said first and second voltage levels have opposite polarities.
Claim 12
Dependent Claim
34 words
The method of claim 1 further comprising the steps of: (g) removing said workpiece from the electrostatic chuck after the workpiece has been physically dechucked; and (h) applying a plasma to the electrostatic chuck.
Claim 13
Independent Claim
92 words
A method of dechucking a workpiece from an electrostatic chuck comprising the steps of: (a) applying a heat transfer gas at a predefined flow rate to a workpiece-to-electrostatic chuck interface; (b) altering a chucking voltage applied to said electrostatic chuck, the chucking voltage having a magnitude with any polarity; (c) monitoring the flow rate for a flow burp; (d) when the flow bump is detected, maintaining the chucking voltage at a fixed magnitude for a predefined period of time and physically dechucking the workpiece; (e) otherwise, repeating steps (b), (c), and (d).
Claim 14
Independent Claim
92 words
A method of dechucking a workpiece from an electrostatic chuck comprising the steps of: (a) applying a heat transfer gas at a predefined flow rate to a workpiece-to-electrostatic chuck interface; (b) altering a chucking voltage applied to said electrostatic chuck, the chucking voltage having a magnitude with any polarity; (c) monitoring the flow rate for a flow burp; (d) when the flow bump is detected, maintaining the chucking voltage at a fixed magnitude for a predefined period of time and physically dechucking the workpiece; (e) otherwise, repeating steps (b), (c), and (d).
Claim 15
Dependent Claim
47 words
The method of claim 12 wherein said monitoring step further comprises the steps of: measuring the flow rate; comparing the measured flow rate to a threshold flow rate level; and when the measured flow rate exceeds the threshold level, indicating that a flow burp has been detected.
Claim 16
Dependent Claim
21 words
The method of claim 12 wherein said voltage altering step further comprises the step of changing a magnitude of said voltage.
Claim 17
Dependent Claim
21 words
The method of claim 12 wherein said voltage altering step further comprises the step of changing a polarity of said voltage.
Claim 18
Dependent Claim
38 words
The method of claim 12 wherein said voltage altering step further comprises the step of decrementing said voltage from a first voltage level toward a second voltage level, where said first and second voltage levels have opposite polarities.
Claim 19
Dependent Claim
34 words
The method of claim 12 further comprising the steps of: (g) removing said workpiece from the electrostatic chuck after the workpiece has been physically dechucked; and (h) applying a plasma to the electrostatic chuck.
Claim 20
Independent Claim
97 words
A method of dechucking a workpiece from an electrostatic chuck comprising the steps of: (a) applying a heat transfer gas at a predefined flow rate to a workpiece-to-electrostatic chuck interface; (b) decrementing said voltage from a first voltage level toward a second voltage level, where said first and second voltage levels have opposite polarities; (c) monitoring the flow rate for a flow burp; (d) when the flow burp is detected, maintaining the chucking voltage at a fixed magnitude for a predefined period of time and physically dechucking the workpiece; (e) otherwise, repeating steps (b), (c), and (d).
Claim 21
Independent Claim
97 words
A method of dechucking a workpiece from an electrostatic chuck comprising the steps of: (a) applying a heat transfer gas at a predefined flow rate to a workpiece-to-electrostatic chuck interface; (b) decrementing said voltage from a first voltage level toward a second voltage level, where said first and second voltage levels have opposite polarities; (c) monitoring the flow rate for a flow burp; (d) when the flow burp is detected, maintaining the chucking voltage at a fixed magnitude for a predefined period of time and physically dechucking the workpiece; (e) otherwise, repeating steps (b), (c), and (d).
Claim 22
Dependent Claim
47 words
The method of claim 18 wherein said monitoring step further comprises the steps of: measuring the flow rate; comparing the measured flow rate to a threshold flow rate level; and when the measured flow rate exceeds the threshold level, indicating that a flow burp has been detected.
Claim 23
Dependent Claim
34 words
The method of claim 18 further comprising the steps of: (g) removing said workpiece from the electrostatic chuck after the workpiece has been physically dechucked; and (h) applying a plasma to the electrostatic chuck.
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