Platen for electrostatic wafer clamping apparatus

• US 6,660,665 B2
• Filed: 05/01/2002
• Issued: 12/09/2003
• Est. Priority Date: 05/01/2002
• Status: Expired due to Term

• Current Assignee: Trek Japan KK (Advanced Energy Industries Incorporated), Japan Fine Ceramics Center, TREK, Inc. (Thermo Fisher Scientific Incorporated)
• Original Assignee: Trek Japan KK (Advanced Energy Industries Incorporated), Japan Fine Ceramics Center, TREK, Inc. (Thermo Fisher Scientific Incorporated)
• Inventors: Kawashima, Naoki, Uehara, Toshio, Matsubara, Hideaki, Yanagida, Hiroaki, Williams, Bruce T., Aoki, Shoji, Okuhara, Yoshiki
• Primary Examiner(s): Smith, Matthew
• Assistant Examiner(s): YEVSIKOV, VICTOR V
• Application Number:
  US10/137,790
• Publication Number:
  US 20030207596A1
• Time in Patent Office: 587 Days
• Field of Search: 438/780, 438/800, 361/234, 361/230, 361/233, 361/235, 428/209, 428/210, 428/692, 428/698, 428/67, 427/63, 427/580, 427/540, 414/935, 269/903, 269/21
• US Class Current: 438/800
• CPC Class Codes: H01L 21/6833 Details of electrostatic chucks
• CPC Class Codes: H02N 13/00 Clutches or holding devices using electrostatic attraction, e.g. using Johnson-Rahbek effect
• CPC Class Codes: Y10T 279/23 with magnetic or electrostatic means
• CPC Class Codes: Y10T 428/24917 including metal layer

Abstract

A platen for electrostatic wafer clamping apparatus comprising a platen body of dielectric material and grains of electrically conductive material diffused in the dielectric material so that the platen has a relatively large electrostatic capacitance due to the diffusion of the conductive grains with the result that the platen provides an increased clamping force regardless of humidity. In accordance with another aspect of the invention, the thickness of the platen body can be decreased by an amount sufficient to maintain a constant clamping force with reduced applied voltage, to eliminate any residual voltage on the platen and to increase the speed of wafer release. The grains of electrically conductive material are present in an amount of from about 2.5 percent to about 15.0 percent of the volume of the platen body, and the grains of electrically conductive material are selected from the group consisting of carbonated transition metals, nitrified transition metals and carbonated grains. The dielectric material preferably is Al₂O₃, and the grains of electrically conductive material preferably are TiC and preferably in an amount of about 5% of the volume of the platen.

Claims

1. A platen for electrostatic wafer clamping apparatus comprising:

a) a platen body of dielectric material; and

b) grains of electrically conductive material diffused in the dielectric material in an amount of from about 2.5 percent to about 15.0 percent of the volume of the platen body.

2. The platen according to claim 1, wherein the dielectric material comprises Al₂O₃.

3. The platen according to claim 1, wherein the grains of electrically conductive material are selected from the group consisting of carbonated transition metals, nitrified transition metals and carbonated grains.

4. The platen according to claim 1, wherein the dielectric material comprises Al₂O₃ and the grains of electrically conductive material comprise TiC.

5. The platen according to claim 1, wherein TiC is present in an amount of about 5.0 percent of the volume of the platen body.

6. A platen for electrostatic wafer clamping apparatus comprising:

a) a platen body of dielectric material having a predetermined thickness;

b) grains of electrically conductive material diffused in the dielectric material; and

c) so that the platen has a relatively large electrostatic capacitance due to the diffusion of the conductive grains with the result that the platen provides an increased clamping force regardless of ambient humidity.

7. The platen according to claim 6, wherein the thickness of the platen body is decreased by an amount sufficient to provide the same amount of clamping force with a reduced magnitude of applied voltage.

8. The platen according to claim 6, wherein the thickness of the platen body is reduced by an amount sufficient to eliminate any residual voltage on the platen.

9. The platen according to claim 6, wherein the thickness of the platen body is reduced by an amount sufficient to increase the speed of wafer release.

10. A platen for electrostatic wafer clamping apparatus comprising a platen body of Al₂O₃ dielectric material having grains of electrically conductive TiC diffused therein.

11. The platen according to claim 10, wherein the grains of TiC are present in an amount of about 5 percent of the volume of the platen body.

12. The platen according to claim 10, wherein the platen body has a thickness of about 0.3 mm.

13. The platen according to claim 10, wherein the platen body has a thickness of about 0.1 mm.

14. A method of making a platen for electrostatic wafer clamping apparatus comprising:

a) mixing dielectric ceramic material and electrically conductive ceramic material in a solvent;

b) drying the resulting mixture;

c) forming the resulting mixture into the shape of a platen; and

d) sintering the shaped product.

15. The method according to claim 14, wherein the dielectric ceramic material comprises alumina ceramic power and the conductive ceramic material comprises titanium carbide ceramic powder.

16. The method according to claim 15, wherein the solvent is ethanol.

17. The method according to claim 15, wherein the sintering is performed at a temperature of about 1600°

C.

18. The method according to claim 15, further includes grinding and polishing the resulting product after sintering.