High surface resistivity electrostatic chuck
View Patent ↗In accordance with an embodiment of the invention, there is provided an electrostatic chuck. The electrostatic chuck comprises an electrode, and a surface layer activated by a voltage in the electrode to form an electric charge to electrostatically clamp a substrate to the electrostatic chuck, the surface layer including a charge control layer comprising a surface resistivity of greater than about 10 11 ohms per square.
1. An electrostatic chuck comprising:
an electrode; and
a surface layer activated by a voltage in the electrode to form an electric charge to electrostatically clamp a substrate to the electrostatic chuck, the surface layer including:
(i) a dielectric;
(ii) a charge control layer comprising a polymer, and comprising a surface resistivity of from about 1×10 12 ohms/square to about 1×10 16 ohms/square, wherein the polymer included in the charge control layer comprises at least one of polyetherimide (PEI) and polyether ether ketone (PEEK); and
(iii) a 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 charge control layer comprises a surface resistivity of from about 1×10 13 ohms/square to about 1×10 16 ohms/square.
3. An electrostatic chuck according to claim 1 , wherein the polymer of which the plurality of polymer protrusions are formed comprises at least one of polyetherimide (PEI), polyimide and polyether ether ketone (PEEK).
4. 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 charge control layer comprises a surface resistivity of from about 1×10 13 ohms/square to about 1×10 16 ohms/square.
5. A method of manufacturing an electrostatic chuck, the method comprising:
forming a surface layer in the electrostatic chuck, the surface layer comprising:
(i) a dielectric;
(ii) a charge control layer comprising a polymer, and comprising a surface resistivity of from about 1×10 12 ohms/square to about 1×10 16 ohms/square, wherein the polymer included in the charge control layer comprises at least one of polyetherimide (PEI) and polyether ether ketone (PEEK); and
(iii) a 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.
6. A method according to claim 5 , wherein the charge control layer comprises a surface resistivity of from about 1×10 13 ohms/square to about 1×10 16 ohms/square.
7. A method according to claim 5 , wherein the method comprising reducing frequency of wafer sticking in use of the electrostatic chuck without modifying the functioning of the electrostatic chuck, including by not modifying at least one of the power supply, electrode structure, dielectric thickness, mechanical properties and clamping force of the electrostatic chuck.
8. A method according to claim 5 , wherein the forming the charge control layer comprises altering the surface resistivity of a surface layer that has already been produced.
9. A method according to claim 8 , wherein the altering the surface resistivity comprises treating the surface layer, which has already been produced, using a reactive ion etch process.
10. A method according to claim 9 , wherein the altering the surface resistivity comprises performing at least one of a plasma treatment, a chemical treatment and a rehydrogenation treatment of the surface layer that has already been produced.
11. A method according to claim 9 , wherein the altering of the surface resistivity produces a surface resistivity after treatment that is within plus or minus 25% of what the surface resistivity would have been prior to treatment.
12. A method according to claim 9 , wherein the method comprises, prior to forming the charge control layer:
bonding a dielectric layer of the electrostatic chuck to an insulator layer of the electrostatic chuck;
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 the charge control layer comprising the 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);
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 the 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.
13. A method of manufacturing an electrostatic chuck, the method comprising:
forming a charge control layer in the electrostatic chuck, the charge control layer comprising at least one of silicon containing oxide, silicon containing carbide, non-stoichiometric silicon containing oxide, non-stoichiometric silicon containing carbide, carbon and a nitride compound of carbon, and comprising a surface resistivity of from about 1×10 12 ohms/square to about 1×10 16 ohms/square;
wherein the method comprises reducing frequency of wafer sticking in use of the electrostatic chuck without modifying the functioning of the electrostatic chuck, including by not modifying at least one of the power supply, electrode structure, dielectric thickness, mechanical properties and clamping force of the electrostatic chuck.
14. A method of manufacturing an electrostatic chuck, the method comprising:
forming a charge control layer in the electrostatic chuck, the charge control layer comprising at least one of silicon containing oxide, silicon containing carbide, non-stoichiometric silicon containing oxide, non-stoichiometric silicon containing carbide, carbon and a nitride compound of carbon, and comprising a surface resistivity of from about 1×10 12 ohms/square to about 1×10 16 ohms/square;
wherein the forming the charge control layer comprises altering the surface resistivity of a surface layer that has already been produced;
wherein the altering the surface resistivity comprises treating the surface layer, which has already been produced, using a reactive ion etch process; and
wherein the altering of the surface resistivity produces a surface resistivity after treatment that is within plus or minus 25% of what the surface resistivity would have been prior to treatment.