Electrostatic chuck with polymer protrusions
View Patent ↗In accordance with an embodiment of the invention, there is provided an electrostatic chuck. The electrostatic chuck comprises 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 includes a plurality of polymer protrusions and a charge control layer to which the plurality of polymer protrusions adhere, the plurality of polymer protrusions extending to a height above portions of the charge control layer surrounding the plurality of polymer protrusions to support the substrate upon the plurality of polymer protrusions during electrostatic clamping of the substrate.
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 polymer protrusions and a charge control layer to which the plurality of polymer protrusions adhere, the charge control layer being a polymer charge control layer and comprising a surface resistivity of between about 10 8 ohms per square to about 10 11 ohms per square, the plurality of polymer protrusions extending to a height above portions of the charge control layer surrounding the plurality of polymer protrusions to support the substrate upon the plurality of polymer protrusions during electrostatic clamping of the substrate.
2. An electrostatic chuck according to claim 1 , wherein the polymer of which the plurality of polymer protrusions are formed comprises polyetherimide (PEI).
3. An electrostatic chuck according to claim 2 , wherein the charge control layer is formed of polyetherimide (PEI).
4. An electrostatic chuck according to claim 1 , wherein the polymer of which the plurality of polymer protrusions are formed comprises polyether ether ketone (PEEK).
5. An electrostatic chuck according to claim 1 , wherein the polymer of which the plurality of polymer protrusions are formed comprises polyimide.
6. An electrostatic chuck according to claim 1 , wherein the charge control layer is formed of polyetherimide (PEI).
7. An electrostatic chuck according to claim 1 , wherein the charge control layer is formed of polyether ether ketone (PEEK).
8. An electrostatic chuck according to claim 7 , wherein the polymer of which the plurality of polymer protrusions are formed comprises polyether ether ketone (PEEK).
9. An electrostatic chuck according to claim 1 , wherein the charge control layer is formed of polyimide.
10. An electrostatic chuck according to claim 9 , wherein the polymer of which the plurality of polymer protrusions are formed comprises polyimide.
11. An electrostatic chuck according to claim 1 , further comprising an adhesive layer underlying the charge control layer.
12. An electrostatic chuck according to claim 11 , wherein the adhesive layer comprises polyetherimide (PEI).
13. An electrostatic chuck according to claim 1 , further comprising an adhesion coating layer.
14. An electrostatic chuck according to claim 13 , wherein the adhesion coating layer comprises at least one of silicon containing nitride, silicon containing oxide, silicon containing carbide, non-stoichiometric silicon containing nitride, non-stoichiometric silicon containing oxide, non-stoichiometric silicon containing carbide, carbon and a nitride compound of carbon.
15. An electrostatic chuck according to claim 14 , wherein the adhesion coating layer comprises at least one of SiO x N y , silicon nitride, silicon oxide, silicon carbide, and diamond-like carbon.
16. An electrostatic chuck according to claim 13 , wherein the adhesion coating layer extends to comprise a metals reduction layer surrounding at least a portion of an edge of the electrostatic chuck.
17. An electrostatic chuck according to claim 1 , further comprising a ceramic to ceramic bonding layer that bonds a dielectric layer of the electrostatic chuck to an insulator layer of the electrostatic chuck, the ceramic to ceramic bonding layer comprising a polymer.
18. An electrostatic chuck according to claim 17 , wherein the polymer of the ceramic to ceramic bonding layer comprises at least one of polytetrafluoroethylene (PTFE) and modified polytetrafluoroethylene (PTFE).
19. An electrostatic chuck according to claim 18 , wherein the modified polytetrafluoroethylene (PTFE) comprises at least one of perfluoroalkoxy (PFA) and fluorinated ethylene-propylene (FEP).
20. An electrostatic chuck according to claim 17 , wherein the polymer of the ceramic to ceramic bonding layer comprises at least one of perfluoroalkoxy (PFA), fluorinated ethylene-propylene (FEP) and polyether ether ketone (PEEK).
21. An electrostatic chuck according to claim 1 , wherein the plurality of polymer protrusions are substantially equally spaced across the surface layer as measured by center to center distance between pairs of neighboring polymer protrusions.
22. An electrostatic chuck according to claim 21 , wherein the protrusions are arranged in a trigonal pattern.
23. An electrostatic chuck according to claim 22 , wherein the polymer protrusions comprise a center to center distance of between about 6 mm and about 8 mm.
24. An electrostatic chuck according to claim 22 , wherein the polymer protrusions comprise a height of between about 3 microns and about 12 microns.
25. An electrostatic chuck according to claim 22 , wherein the polymer protrusions comprise a diameter of about 900 microns.
26. An electrostatic chuck according to claim 1 , further comprising a gas seal ring comprising a polymer.
27. An electrostatic chuck according to claim 26 , wherein the gas seal ring comprises at least one of polyetherimide (PEI), polyimide and polyether ether ketone (PEEK).
28. An electrostatic chuck according to claim 1 , wherein the plurality of polymer protrusions comprise a surface roughness of between about 0.02 μm and about 0.05 μm.
29. An electrostatic chuck according to claim 1 , wherein the polymer of which the plurality of polymer protrusions are formed comprises polyetherimide (PEI), wherein the charge control layer is formed of polyetherimide (PEI), and wherein the electrostatic chuck comprises an adhesion coating layer comprising at least one of silicon containing nitride, silicon containing oxide, silicon containing carbide, non-stoichiometric silicon containing nitride, non-stoichiometric silicon containing oxide, non-stoichiometric silicon containing carbide, carbon and a nitride compound of carbon.
30. An electrostatic chuck according to claim 29 , further comprising a ceramic to ceramic bonding layer that bonds a dielectric layer of the electrostatic chuck to an insulator layer of the electrostatic chuck, the ceramic to ceramic bonding layer comprising at least one of polytetrafluoroethylene (PTFE) and modified polytetrafluoroethylene (PTFE).
31. A method of manufacturing an electrostatic chuck, the method comprising:
bonding a dielectric layer of the electrostatic chuck to an insulator layer of the electrostatic chuck using a bonding polymer comprising at least one of polytetrafluoroethylene (PTFE), modified polytetrafluoroethylene (PTFE), perfluoroalkoxy (PFA), fluorinated ethylene-propylene (FEP) and polyether ether ketone (PEEK);
coating the dielectric layer of the electrostatic chuck with an adhesion coating layer comprising at least one of silicon containing nitride, silicon containing oxide, silicon containing carbide, non-stoichiometric silicon containing nitride, non-stoichiometric silicon containing oxide, non-stoichiometric silicon containing carbide, carbon and a nitride compound of carbon;
bonding a charge control layer comprising a charge control layer polymer to the surface of the electrostatic chuck, the charge control layer polymer comprising at least one of polyetherimide (PEI), polyimide and polyether ether ketone (PEEK), the charge control layer comprising a surface resistivity of between about 10 8 ohms per square to about 10 11 ohms per square;
depositing a photoresist onto the charge control layer;
reactive ion etching the charge control layer to remove portions of the charge control layer that will surround a plurality of polymer protrusions being formed in the charge control layer; and
stripping the photoresist off the electrostatic chuck, thereby revealing the plurality of polymer protrusions being formed of the same charge control layer polymer as the charge control layer.