Electrostatic chuck with photo-patternable soft protrusion contact surface

• US 9,721,821 B2
• Filed: 10/29/2013
• Issued: 08/01/2017
• Est. Priority Date: 05/15/2009
• Status: Active Grant

• Current Assignee: Entegris Incorporated
• Original Assignee: Entegris Incorporated
• Inventors: Lin, I-Kuan, Cooke, Richard A., Rybczynski, Jakub
• Primary Examiner(s): Jackson, Stephen W
• Application Number:
  US14/439,464
• Publication Number:
  US 20150294891A1
• Time in Patent Office: 1,372 Days
• Field of Search: 361234
• CPC Class Codes: C23C 16/4581 characterised by material of construction or surface finish of the means for supporting the substrate
• CPC Class Codes: H01L 21/6831 using electrostatic chucks
• CPC Class Codes: H01L 21/6875 characterised by a plurality of individual support members, e.g. support posts or protrusions
• CPC Class Codes: H01L 21/68757 characterised by a coating or a hardness or a material
• CPC Class Codes: H02N 13/00 Clutches or holding devices using electrostatic attraction, e.g. using Johnson-Rahbek effect

Abstract

In accordance with an embodiment of the invention, there is provided a soft protrusion structure for an electrostatic chuck, which offers a non-abrasive contact surface for wafers, workpieces or other substrates, while also having improved manufacturability and compatibility with grounded surface platen designs. The soft protrusion structure comprises a photo-patternable polymer.

Claims

1. An electrostatic chuck comprising:

a surface layer activated by a voltage in an electrode to form an electric charge to electrostatically clamp a substrate to the electrostatic chuck, the surface layer including a plurality of hard-baked photo-patterned polymer protrusions comprising a hard-baked photo-patterned polymer and a charge control layer to which the plurality of hard-baked photo-patterned polymer protrusions adhere, the plurality of hard-baked photo-patterned polymer protrusions extending to a height above portions of the charge control layer surrounding the plurality of hard-baked photo-patterned polymer protrusions to support the substrate upon the plurality of hard-baked photo-patterned polymer protrusions during electrostatic clamping of the substrate.

2. An electrostatic chuck according to claim 1, wherein the hard-baked photo-patterned polymer comprises a polymer that, prior to baking, is photo-patternable, and liquid at room temperature.

3. An electrostatic chuck according to claim 1, wherein the hard-baked photo-patterned polymer comprises a polymer that, prior to baking, is photo-patternable, and solid at room temperature.

4. An electrostatic chuck according to claim 1, wherein the hard-baked photo-patterned polymer comprises an epoxy based polymer that, prior to baking, is photo-patternable.

5. An electrostatic chuck according to claim 1, wherein the hard-baked photo-patterned polymer comprises at least one of a polyimide based polymer and a benzocyclobutene based polymer, the hard-baked photo-patternable polymer being a polymer that, prior to baking, is photo-patternable.

6. An electrostatic chuck according to claim 1, wherein the charge control layer comprises silicon carbide.

7. An electrostatic chuck according to claim 1, wherein the charge control layer comprises diamond like carbon.

8. An electrostatic chuck according to claim 1, wherein the charge control layer comprises a surface resistivity of between about 10⁸ ohms per square to about 10¹¹ ohms per square.

9. An electrostatic chuck according to claim 1, wherein the hard-baked photo-patterned polymer protrusions comprise a height of between about 3 microns and about 12 microns.

10. An electrostatic chuck according to claim 1, further comprising a gas seal ring comprising a hard-baked photo-patterned polymer.

11. An electrostatic chuck according to claim 1, wherein the plurality of hard-baked polymer protrusions comprise a surface roughness of between about 0.02 μ

m and about 0.05 μ

m.

12. An electrostatic chuck according to claim 1, wherein the hard-baked photo-patterned polymer comprises a material having a tensile strength of greater than about 70 megapascals (MPa).

13. An electrostatic chuck according to claim 1, wherein the hard-baked photo-patterned polymer comprises a material having a Young'"'"'s modulus of less than about 3.5 gigapascals (GPa).

14. An electrostatic chuck according to claim 1, further comprising a conductive path covering at least a portion of a workpiece-contacting surface of a gas seal ring of the electrostatic chuck, the conductive path comprising at least a portion of an electrical path to ground.

15. An electrostatic chuck according to claim 14, wherein the hard-baked photo-patterned polymer comprises a polymer that, prior to baking, is photo-patternable, and liquid at room temperature, and wherein the charge control layer comprises a surface resistivity of between about 10⁸ ohms per square to about 10¹¹ ohms per square.

16. A method of manufacturing an electrostatic chuck, the method comprising:

exposing a photo-patternable polymer, on a surface of the electrostatic chuck, to light through a mask, the electrostatic chuck comprising a charge control layer underlying at least a portion of the photo-patternable polymer;

removing areas of the surface of the electrostatic chuck based on a pattern of exposure of the surface to the light through the mask, thereby forming a plurality of polymer protrusions on the surface of the electrostatic chuck, the plurality of polymer protrusions adhering to the charge control layer and extending to a height above portions of the charge control layer surrounding the plurality of polymer protrusions, and

hard-baking the plurality of polymer protrusions to form a plurality of protrusion comprising hard-baked photo-patterned polymer.

17. A method according to claim 16, comprising laminating a polymer sheet including the photo-patternable polymer over at least a portion of the charge control layer.

18. A method according to claim 16, comprising spraying a liquid polymer including the photo-patternable polymer over at least a portion of the charge control layer.

19. A method according to claim 16, wherein the plurality of protrusions comprising hard-baked photo-patterned polymer comprises a material having a tensile strength of greater than about 70 megapascals (MPa) and having a Young'"'"'s modulus of less than about 3.5 gigapascals (GPa).

20. A method according to claim 16, further comprising covering at least a portion of a workpiece-contacting surface of a gas seal ring of the electrostatic chuck with a conductive, path, the conductive path comprising at least a portion of an electrical path to ground.