US5315473A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Isolated electrostatic chuck and excitation method
Assignee: Applied Materials Inc
•
Filing: 1992-01-21
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Granted: 1994-05-24
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Expires: 2012-01-21
Abstract
Abstract An electrostatic clamp or chuck and method uses soft square wave, slew rate limited, A.C. clamping voltages and a balanced, differential drive for clamping flat articles such as semiconductor wafers to pedestals, wafer transfer blades, and the like, with a large ratio of clamping force to clamping voltage, reduced decay of the clamping force and associated nearly constant maximum clamping force, instantaneous elimination of remnant clamping force when the clamping voltage is removed (instant off operation), isolation of the clamped article from the clamping voltage, and substantial elimination of vibration. Preferably the A.C. frequency is 0.1 to 60 Hz. The instant off operation is enhanced by increasing the frequency as the clamping voltage is decreased.
Inventors
- 👤 Kenneth S. Collins
- 👤 Edward A. Gritters
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 17:17
CPC Classifications
H; H10; H10P; H10P72/00; H10P72/70; H10P72/72; H10P72/722
Claims Analysis
Total Claims: 42
Claim 1
Independent Claim
50 words
A method of electrostatically clamping a workpiece to a support having at least a pair of dielectrically isolated electrodes comprising: applying to the paired electrodes an alternating current square-wave voltage of a frequency greater than 0.1 Hz and of a magnitude sufficient to clamp the workpiece flat against the support.
Claim 2
Independent Claim
50 words
A method of electrostatically clamping a workpiece to a support having at least a pair of dielectrically isolated electrodes comprising: applying to the paired electrodes an alternating current square-wave voltage of a frequency greater than 0.1 Hz and of a magnitude sufficient to clamp the workpiece flat against the support.
Claim 3
Dependent Claim
23 words
The method of claim 1 wherein the frequency of the applied voltage is with the range of about 0.1 to about 60 Hz.
Claim 4
Dependent Claim
23 words
The method of claim 2 wherein the frequency of the applied voltage is within the range of about 0.1 to about 10 Hz.
Claim 5
Dependent Claim
16 words
The method of claim 3 wherein the frequency of the applied voltage is about 1 Hz.
Claim 6
Dependent Claim
28 words
The method of claim 1 further comprising turning off the clamping force by increasing the frequency of the clamping voltage while simultaneously decreasing the magnitude of the voltage.
Claim 7
Dependent Claim
24 words
The method of claim 1 wherein the magnitude of the applied voltage is within the range of from about 500 to about 2000 volts.
Claim 8
Dependent Claim
14 words
The method of claim 5 wherein the turn off frequency is over 60 Hz.
Claim 9
Dependent Claim
13 words
The method of claim 1 wherein the applied voltage is slew rate limited.
Claim 10
Dependent Claim
13 words
The method of claim 1 wherein alternate electrodes are connected in common electrically.
Claim 11
Independent Claim
63 words
A method of electrostatically clamping a semiconductor wafer to a wafer support which includes a layer of dielectric material over at least a pair of electrodes comprising: applying to the paired electrodes a differentially driven, balanced, alternating current square-wave voltage having a frequency of about 0.1 to about 60 Hz and a magnitude sufficient to clamp the semiconductor wafer flat against the support.
Claim 12
Independent Claim
63 words
A method of electrostatically clamping a semiconductor wafer to a wafer support which includes a layer of dielectric material over at least a pair of electrodes comprising: applying to the paired electrodes a differentially driven, balanced, alternating current square-wave voltage having a frequency of about 0.1 to about 60 Hz and a magnitude sufficient to clamp the semiconductor wafer flat against the support.
Claim 13
Dependent Claim
24 words
The method of claim 10 wherein the frequency of the applied voltage is in the range of from about 0.1 to about 10 Hz.
Claim 14
Dependent Claim
16 words
The method of claim 10 wherein the frequency of the applied voltage is about 1 Hz.
Claim 15
Dependent Claim
23 words
The method of claim 10 wherein the magnitude of the applied voltage is within the range of about 500 to about 2000 volts.
Claim 16
Dependent Claim
13 words
The method of claim 10 wherein alternate electrodes are connected in common electrically.
Claim 17
Dependent Claim
28 words
The method of claim 10 further comprising turning off the clamping force by increasing the frequency of the clamping voltage while simultaneously decreasing the magnitude of the voltage.
Claim 18
Dependent Claim
14 words
The method of claim 15 wherein the turn off frequency is over 60 Hz.
Claim 19
Dependent Claim
93 words
An electrostatic clamp comprising: an array of at least a pair of electrodes formed on a base, alternating electrodes being connected in common electrically; a layer of non-resilient dielectric material over the electrodes and the base, said dielectric material having a thickness sufficient to dielectrically isolate the electrodes and to prevent dielectric breakdown when a clamping voltage is applied; and means for applying a square-wave alternating voltage having a frequency greater than about 0.1 Hz between the alternating electrodes to generate an electrostatic clamping force between the clamp and a workpiece positioned thereon.
Claim 20
Dependent Claim
93 words
An electrostatic clamp comprising: an array of at least a pair of electrodes formed on a base, alternating electrodes being connected in common electrically; a layer of non-resilient dielectric material over the electrodes and the base, said dielectric material having a thickness sufficient to dielectrically isolate the electrodes and to prevent dielectric breakdown when a clamping voltage is applied; and means for applying a square-wave alternating voltage having a frequency greater than about 0.1 Hz between the alternating electrodes to generate an electrostatic clamping force between the clamp and a workpiece positioned thereon.
Claim 21
Dependent Claim
29 words
The clamp of claim 17 wherein the means for applying said voltage applies a voltage of a frequency within the range of from about 0.1 to about 60 Hz.
Claim 22
Dependent Claim
24 words
The clamp of claim 18 wherein the frequency of the applied voltage is within the range of from about 0.1 to about 10 Hz.
Claim 23
Dependent Claim
16 words
The clamp of claim 19 wherein the frequency of the applied voltage is about 1 Hz.
Claim 24
Dependent Claim
13 words
The clamp of claim 17 wherein the applied voltage is slew rate limited.
Claim 25
Dependent Claim
12 words
The clamp of claim 17 wherein said dielectric material is aluminum oxide.
Claim 26
Dependent Claim
19 words
The clamp of claim 22 wherein said dielectric material has a thickness of about 2 to about 15 mils.
Claim 27
Dependent Claim
24 words
The clamp of claim 17 wherein the magnitude of the applied voltage is within the range of from about 500 to about 2000 volts.
Claim 28
Dependent Claim
101 words
An electrostatic clamp comprising a flat base; an array comprising a plurality of electrodes formed on the base, alternate electrodes of the array being connected in common electrically; a layer of non-resilient dielectric material over the electrodes and the base, said dielectric material having a thickness sufficient to prevent dielectric breakdown when a clamping voltage is applied; and means for applying a differentially drive, balanced, square-wave, alternating voltage having a frequency within the range of about 0.1 to about 60 Hz between the alternating electrodes, whereby an electrostatic clamping force is generated between the clamp and a semiconductor wafer positioned thereon.
Claim 29
Dependent Claim
101 words
An electrostatic clamp comprising a flat base; an array comprising a plurality of electrodes formed on the base, alternate electrodes of the array being connected in common electrically; a layer of non-resilient dielectric material over the electrodes and the base, said dielectric material having a thickness sufficient to prevent dielectric breakdown when a clamping voltage is applied; and means for applying a differentially drive, balanced, square-wave, alternating voltage having a frequency within the range of about 0.1 to about 60 Hz between the alternating electrodes, whereby an electrostatic clamping force is generated between the clamp and a semiconductor wafer positioned thereon.
Claim 30
Dependent Claim
17 words
An electrostatic clamp of claim 25 wherein the frequency of the applied voltage is about 1 Hz.
Claim 31
Dependent Claim
13 words
An electrostatic clamp of claim 25 wherein said dielectric material is aluminum oxide.
Claim 32
Dependent Claim
20 words
An electrostatic clamp of claim 27 wherein said dielectric material has a thickness of about 2 to about 15 mils.
Claim 33
Dependent Claim
20 words
An electrostatic clamp of claim 25 wherein the magnitude of the applied voltage is about 500 to about 2000 volts.
Claim 34
Dependent Claim
27 words
An electrostatic clamp of claim 25 wherein the ratio of the width of the electrodes to the distance between the electrodes is about 3/1 to about 2/1.
Claim 35
Dependent Claim
17 words
An electrostatic clamp of claim 25 wherein the electrode width is about 12 to about 120 mils.
Claim 36
Dependent Claim
19 words
An electrostatic clamp of claim 25 wherein the distance between the electrodes is about 6 to about 40 mils.
Claim 37
Dependent Claim
14 words
An electrostatic clamp of claim 25 wherein the base is a wafer transfer blade.
Claim 38
Dependent Claim
29 words
An electrostatic clamp of claim 25 wherein the base is a wafer support pedestal adapted for applying heat transfer gas under pressure between the pedestal and the wafer thereon.
Claim 39
Dependent Claim
13 words
The method of claim 1 wherein said support is a wafer transfer blade.
Claim 40
Dependent Claim
13 words
The method of claim 10 wherein said support is a wafer transfer blade.
Claim 41
Independent Claim
146 words
A method for transporting wafers in a wafer fabrication system utilizing an electrostatic wafer blade comprising a) placing a wafer to be transported on a top surface of the blade, said top surface having at least one pair of interleaved electrodes, alternating electrodes being connected in common electrically; said electrodes having a width and a spatial distance between said electrodes based on a correlated ratio defined by (electrode width/distance between electrodes) ranging from 3/1 to 21; b) applying a square wave alternating voltage having a frequency greater than 0.1 Hz between the alternating electrodes to generate an electrostatic clamping force between the blade and the wafer thereon; and c) accelerating the movement of the blade with a mechanical arm attached to the blade to effectuate controlled movement of the wafer in the system, whereby said clamping force holds the wafer onto the blade during accelerational movement.
Claim 42
Independent Claim
146 words
A method for transporting wafers in a wafer fabrication system utilizing an electrostatic wafer blade comprising a) placing a wafer to be transported on a top surface of the blade, said top surface having at least one pair of interleaved electrodes, alternating electrodes being connected in common electrically; said electrodes having a width and a spatial distance between said electrodes based on a correlated ratio defined by (electrode width/distance between electrodes) ranging from 3/1 to 21; b) applying a square wave alternating voltage having a frequency greater than 0.1 Hz between the alternating electrodes to generate an electrostatic clamping force between the blade and the wafer thereon; and c) accelerating the movement of the blade with a mechanical arm attached to the blade to effectuate controlled movement of the wafer in the system, whereby said clamping force holds the wafer onto the blade during accelerational movement.
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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) | 1997-05-23 | 1997-11-22 | 1998-05-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-05-23 | 2001-11-22 | 2002-05-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-05-23 | 2005-11-22 | 2006-05-24 | $7700.00 | Window Closed / Lapsed |