US5818682A
Expired / Lapsed
US
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Method and apparatus for optimizing a dechucking period used to dechuck a workpiece from an electrostatic chuck
Assignee: Applied Materials Inc
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Filing: 1996-08-13
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Granted: 1998-10-06
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Expires: 2016-08-13
Abstract
Abstract A method and apparatus which predicts an optimal period over which a dechucking voltage is applied to an electrostatic chuck to achieve dechucking of a workpiece therefrom. Specifically, the method is implemented as a software program that is executed by a conventional computer. The method applies an optimal dechucking voltage for an optimal dechucking period to dechuck the workpiece. To avoid charge accumulation on the electrostatic chuck when processing a succession of workpieces, the chucking and dechucking voltages reverse polarity after each workpiece is dechucked.
Inventors
- 👤 David H. Loo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 23:25
CPC Classifications
H; H02; H02N; H02N13/00; H10; H10P; H10P72/00; H10P72/70; H10P72/72; H10P72/722; Y; Y10; Y10T; Y10T279/00; Y10T279/23
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
93 words
In a system that retains a workpiece, a method of chucking and dechucking said workpiece to/from an electrostatic chuck comprising the steps of: positioning a workpiece upon said electrostatic chuck; applying a chucking voltage to said electrostatic chuck for a chucking period; applying a dechucking voltage to the electrostatic chuck for a period equivalent to a dechucking period, where said dechucking period is optimized with respect to a predefined optimization constant and the chucking period to provide a minimal residual charge on the electrostatic chuck; and removing the workpiece from the electrostatic chuck.
Claim 2
Dependent Claim
93 words
In a system that retains a workpiece, a method of chucking and dechucking said workpiece to/from an electrostatic chuck comprising the steps of: positioning a workpiece upon said electrostatic chuck; applying a chucking voltage to said electrostatic chuck for a chucking period; applying a dechucking voltage to the electrostatic chuck for a period equivalent to a dechucking period, where said dechucking period is optimized with respect to a predefined optimization constant and the chucking period to provide a minimal residual charge on the electrostatic chuck; and removing the workpiece from the electrostatic chuck.
Claim 3
Dependent Claim
18 words
The method of claim 1 wherein the dechucking period is equivalent to a constant times the chucking period.
Claim 4
Dependent Claim
10 words
The method of claim 2 wherein said constant is 0.0667.
Claim 5
Dependent Claim
19 words
The method of claim 1 wherein the dechucking voltage has a polarity opposite the polarity of the chucking voltage.
Claim 6
Dependent Claim
17 words
The method of claim 1 wherein the dechucking voltage is equivalent to -1.5 times the chucking voltage.
Claim 7
Independent Claim
90 words
A method of dechucking a workpiece from an electrostatic chuck, where the workpiece has been retained by the electrostatic chuck using a chucking voltage that is applied to the electrostatic chuck for a chucking period, the method comprising the steps of: determining a dechucking voltage; determining a dechucking period that is related to a chucking period through a predefined optimization constant to provide a minimal residual charge on the electrostatic chuck; and applying the dechucking voltage to the electrostatic chuck to a period of time equivalent to the dechucking period.
Claim 8
Independent Claim
90 words
A method of dechucking a workpiece from an electrostatic chuck, where the workpiece has been retained by the electrostatic chuck using a chucking voltage that is applied to the electrostatic chuck for a chucking period, the method comprising the steps of: determining a dechucking voltage; determining a dechucking period that is related to a chucking period through a predefined optimization constant to provide a minimal residual charge on the electrostatic chuck; and applying the dechucking voltage to the electrostatic chuck to a period of time equivalent to the dechucking period.
Claim 9
Dependent Claim
70 words
The method of claim 6 wherein said dechucking period is related to said chucking period by the following relationship: Td=(Ra/Rv)Tc where: Ra/Rv is the predefined optimization constant; Ra is a known area ratio having the form Ra=(|Ud'|Td')/(|Uc'|Tc'); Ud' is an optimized dechucking voltage; Td' is an optimized dechucking period; Uc' is an optimized chucking voltage; Tc' is an optimized chucking period; Rv is a voltage ratio having the form Rv=|Ud'|/|Uc'|.
Claim 10
Dependent Claim
25 words
The method of claim 7 wherein said area ratio and said voltage ratio are empirically optimized to achieve minimal residual charge upon the electrostatic chuck.
Claim 11
Dependent Claim
10 words
The method of claim 7 wherein R a equals 0.1.
Claim 12
Dependent Claim
12 words
The method of claim 7 wherein R a /R v equals 0.0667.
Claim 13
Dependent Claim
17 words
The method of claim 6 wherein the dechucking voltage is equivalent to -1.5 times the chucking voltage.
Claim 14
Dependent Claim
107 words
In a system that retains a workpiece, apparatus for chucking and dechucking said workpiece to/from an electrostatic chuck comprising the steps of: means for positioning a workpiece upon said electrostatic chuck; a voltage source, connected to said electrostatic chuck, for applying a chucking voltage to said electrostatic chuck for a chucking period and for applying a dechucking voltage to the electrostatic chuck for a period equivalent to a dechucking period, where said dechucking period is optimized with respect to a predefined optimization constant and the chucking period to provide a minimal residual charge on the electrostatic chuck; and means for removing the workpiece from the electrostatic chuck.
Claim 15
Dependent Claim
107 words
In a system that retains a workpiece, apparatus for chucking and dechucking said workpiece to/from an electrostatic chuck comprising the steps of: means for positioning a workpiece upon said electrostatic chuck; a voltage source, connected to said electrostatic chuck, for applying a chucking voltage to said electrostatic chuck for a chucking period and for applying a dechucking voltage to the electrostatic chuck for a period equivalent to a dechucking period, where said dechucking period is optimized with respect to a predefined optimization constant and the chucking period to provide a minimal residual charge on the electrostatic chuck; and means for removing the workpiece from the electrostatic chuck.
Claim 16
Dependent Claim
18 words
The apparatus of claim 12 wherein the dechucking period is equivalent to a constant times the chucking period.
Claim 17
Dependent Claim
10 words
The apparatus of claim 13 wherein said constant is 0.0667.
Claim 18
Dependent Claim
19 words
The apparatus of claim 12 wherein the dechucking voltage has a polarity opposite the polarity of the chucking voltage.
Claim 19
Dependent Claim
17 words
The apparatus of claim 12 wherein the dechucking voltage is equivalent to -1.5 times the chucking voltage.
Claim 20
Dependent Claim
99 words
Apparatus for dechucking a workpiece from an electrostatic chuck, where the workpiece has been retained by the electrostatic chuck using a chucking voltage that is applied to the electrostatic chuck for a chucking period, the apparatus comprising: means for determining a dechucking voltage; means for determining a dechucking period that is related to a chucking period through a predefined optimization constant to provide a minimal residual charge on the electrostatic chuck; and a voltage source, connected to said electrostatic chuck, for applying the dechucking voltage to the electrostatic chuck to a period of time equivalent to the dechucking period.
Claim 21
Dependent Claim
99 words
Apparatus for dechucking a workpiece from an electrostatic chuck, where the workpiece has been retained by the electrostatic chuck using a chucking voltage that is applied to the electrostatic chuck for a chucking period, the apparatus comprising: means for determining a dechucking voltage; means for determining a dechucking period that is related to a chucking period through a predefined optimization constant to provide a minimal residual charge on the electrostatic chuck; and a voltage source, connected to said electrostatic chuck, for applying the dechucking voltage to the electrostatic chuck to a period of time equivalent to the dechucking period.
Claim 22
Dependent Claim
70 words
The apparatus of claim 17 wherein said dechucking period is related to said chucking period by the following relationship: Td=(Ra/Rv)Tc where: Ra/Rv is the predefined optimization constant: Ra is a known area ratio having the form Ra=(|Ud'|Td')/(|Uc'|TC'); Ud' is an optimized dechucking voltage; Td' is an optimized dechucking period; Uc' is an optimized chucking voltage; Tc' is an optimized chucking period; Rv is a voltage ratio having the form Rv=|Ud'|/|Uc'.
Claim 23
Dependent Claim
25 words
The apparatus of claim 18 wherein said area ratio and said voltage ratio are empirically optimized to achieve minimal residual charge upon the electrostatic chuck.
Claim 24
Dependent Claim
10 words
The apparatus of claim 18 wherein R a equals 0.1.
Claim 25
Dependent Claim
12 words
The apparatus of claim 18 wherein R a /R v equals 0.0667.
Claim 26
Dependent Claim
17 words
The apparatus of claim 17 wherein the dechucking voltage is equivalent to -1.5 times the chucking voltage.
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 2001-10-05 | 2002-04-06 | 2002-10-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-10-05 | 2006-04-06 | 2006-10-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-10-05 | 2010-04-06 | 2010-10-06 | $7700.00 | Window Closed / Lapsed |