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1. WO1997023945 - LOW VOLTAGE ELECTROSTATIC CLAMP FOR SUBSTRATES SUCH AS DIELECTRIC SUBSTRATES

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[ EN ]

WHAT IS CLAIMED IS:

1. An electrostatic clamp for clamping dielectric substrates comprising:
an array of spaced-apart and electrically conductive electrodes formed on a dielectric base, wherein the width of each of the electrodes in the array of electrodes is less than approximately 100 μm, and the spacing between the electrodes is less than approximately 100 μm;
an electrical contact connected to a first group of the electrodes and a second electrical contact connected to a second group of the electrodes, the first and second groups of electrodes alternating with respect to each other in the array of electrodes.

2. The electrostatic clamp according to Claim 1 , wherein the width of the electrodes is less than approximately 50 μm.

3. The electrostatic clamp according to Claim 1, wherein the spacing between the electrodes is less than approximately 50 μm.

4. The electrostatic clamp according to Claim 1 , wherein the spacing between the electrodes is approximately 5 to 20 μm and the width of the electrodes is approximately 5 to 20 μm.

5. The electrostatic clamp according to Claim 1 , wherein the array of electrodes is covered with a dielectric insulating layer.

6. The electrostatic clamp according to Claim 5, wherein the insulating layer is formed of silicon nitride, silicon oxide, aluminum oxide, boron nitride or combinations thereof.

7. The electrostatic clamp according to Claim 5, wherein the insulating layer has a thickness of less than 10 μm.

8. The electrostatic clamp according to Claim 5, wherein the insulating layer has a dielectric constant in a range of 6 to 9.

9. The electrostatic clamp according to Claim 1, wherein the base is formed of glass and the array of electrodes is formed of aluminum.

10. An electrostatic clamp for clamping dielectric substrates comprising:
an array of electrodes formed on a base, each of the electrodes in the array of electrodes having an electrode width and a spacing between electrodes;
an insulating layer covering the array of electrodes;
a first electrical contact connected to alternating electrodes in the array of electrodes;
a second electrical contact connected to remaining electrodes in the array of electrodes which are not connected to the first electrical contact;
a voltage source for applying voltages of less than 1 kV to the first and second electrical contacts, wherein the electrode width and spacing is small enough that less than 1 kV applied to the first and second electrical contacts provides a sufficient clamping force to clamp a dielectric substrate against at least 2 Torr of backside pressure.

1 1. The electrostatic clamp according to Claim 10, wherein the width of the electrodes is less than approximately 100 μm.

12. The electrostatic clamp according to Claim 10, wherein the spacing between the electrodes is less than approximately 100 μm.

13. The electrostatic clamp according to Claim 10, wherein the spacing between the electrodes is approximately 5 to 50 μm and the spacing is approximately 5 to 50 μm.

14. A method of making an electrostatic clamp comprising:
depositing a thin metal film on a dielectric substrate;
forming an array of electrodes by etching the thin metal film by micro-lithography, wherein the electrodes which are formed by the etching have widths of less than approximately 100 μm, and spacings between the electrodes are less than approximately 100 μm;
coating the electrodes with an electrically insulating film; and
connecting common electrical contacts to alternating electrodes in the array of electrodes.

15. The method of making an electrostatic clamp according to Claim 14, wherein the step of depositing the thin metal film includes depositing the thin metal film by sputtering.

16. The method of making an electrostatic clamp according to Claim 14, wherein the step of etching the thin metal film comprises:
coating the thin metal film with photo-resist;
exposing the photo-resist through a mask;
removing the unexposed photo-resist so as to provide exposed metal portions of the metal film; and
etching the exposed metal portions so as to form the array of electrodes from the remainder of the metal film.

17. The method of making an electrostatic clamp according to Claim 14, wherein the step of forming an array of electrodes includes forming electrodes wherein the width of the electrodes is approximately 5 to 50 μm.

18. The method of making an electrostatic clamp according to Claim 14, wherein the step of forming an array of electrodes includes forming electrodes wherein the spacing between the electrodes is between 5 and 50 μm.

19. The method of making an electrostatic clamp according to Claim 14, wherein the step of forming an array of electrodes includes forming electrodes having widths of approximately 5 to 20 μm and spacings between the electrodes of approximately 5 to 20 μm.

20. The method of making an electrostatic clamp according to Claim 14, wherein the step of coating the electrodes with an insulating film includes coating the electrodes with a layer of silicon nitride, boron nitride, aluminum oxide and/or silicon dioxide.

21. The method of making an electrostatic clamp according to Claim 14, wherein the step of depositing the thin metal film includes depositing a thin film of aluminum, chromium, tungsten, molybdenum or metal oxide on a glass substrate.

22. A method of processing a substrate in a process chamber having an electrostatic clamp for supporting the substrate during processing thereof, the method comprising:
supplying a substrate to the process chamber at a position above the electrostatic clamp, the clamp including an array of electrodes having conductor widths of less than 100 μm and spaces between the electrodes of less than 100 μm;
clamping the substrate by supplying sufficient voltage to the clamp to electrostatically attract the substrate against the upper surface of the clamp; and
processing an exposed surface of the substrate.

23. The method of Claim 22, further comprising supplying a heat transfer gas between the lower surface of the substrate and the upper surface of the clamp.

24. The method of Claim 22, wherein the upper surface of the substrate is etched in a plasma environment during the processing step.

25. The method of Claim 22, wherein the upper surface of the substrate is coated in a plasma environment during the processing step.

26. The method of Claim 22, wherein the process chamber is part of an ECR reactor, TCP reactor or parallel plate reactor.

27. The method of Claim 22, wherein the clamp is a bipolar electrostatic chuck and the substrate is a glass panel suitable for use in making a flat panel display.

28. The method of Claim 22, wherein the clamp is a bipolar electrostatic chuck and the substrate is a semiconductor wafer.

29. The method of Claim 21 , wherein the array of electrodes is supplied DC voltage of less than 1000 volts during the clamping step.

30. The method of Claim 22, wherein helium gas is supplied to a space between the lower surface of the substrate and the upper surface of the clamp by passing the helium through one or more channels in the clamp.