Wafer pin chuck fabrication and repair
View Patent ↗In a wafer chuck design featuring pins or “mesas” making up the support surface, engineering the pins to have an annular shape, or to contain holes or pits, minimizes sticking of the wafer, and improves wafer settling. In another aspect of the invention is a tool and method for imparting or restoring flatness and roughness to a surface, such as the support surface of a wafer chuck. The tool is shaped such that the contact to the surface being treated is a circle or annulus. The treatment method may take place in a dedicated apparatus, or in-situ in semiconductor fabrication apparatus. The tool is smaller than the diameter of the wafer pin chuck, and may be approximate to the spatial frequency of the high spots to be lapped. The movement of the tool relative to the support surface is such that all areas of the support surface may be processed by the tool, or only those areas needing correction.
1. A tool for lapping a surface of a component, said tool comprising:
(a) a contacting surface configured to contact the surface of the component, said contacting surface including a material of approximately equal or greater hardness than that of the surface of the component; and
(b) when contacted with a plane, said contacting surface makes line contact, wherein said line contact consists of a closed loop.
2. The tool of claim 1 , wherein said contacting surface has a toroidal shape.
3. The tool of claim 1 , wherein said closed loop comprises a member selected from the group consisting of a circle, oval and ellipse.
4. The tool of claim 1 , wherein the surface of the component is populated with pins.
5. The tool of claim 1 , wherein the component comprises a member selected from the group consisting of a vacuum chuck, and electrostatic chuck, a wafer handling arm, a chuck for supporting a flat panel display, a glass handling arm, and a reticle chuck.
6. The tool of claim 1 , wherein said material of aid contacting surface is the same as that of the surface of the component.
7. The tool of claim 1 , wherein said contacting surface comprises a ceramic material.
8. The tool of claim 1 , wherein said contacting surface comprises a material selected from the group consisting of SiC, B4C, and diamond.
9. The tool of claim 8 , wherein said contacting surface comprises a composite of silicon and silicon carbide.
10. The tool of claim 1 , wherein said contacting surface comprises a flatness that is flatter than a flatness of the wafer chuck support surface as measured across a diameter of said tool contacting surface.
11. The tool of claim 10 , wherein said contacting surface comprises a flatness measurement less than 4.76 nm/mm diameter.
12. The tool of claim 10 , wherein said contacting surface comprises a slope less than 1.68 microradians.
13. The tool of claim 1 , wherein said contacting surface has a size that is less than a diameter of the wafer chuck support surface.
14. The tool of claim 13 , wherein said contacting surface has a size that is on the order of a die size on a semiconductor wafer configured to be supported by the wafer chuck support surface.
15. The tool of claim 13 , wherein said contacting surface has a size ranging from about 3 mm to about 28 mm in diameter.
16. The tool of claim 1 , further comprising structure configured for attachment of said tool to a lapping machine.
17. The tool of claim 16 , wherein said attachment structure comprises an attachment means of minimal constraint.
18. The tool of claim 17 , wherein said attachment means of minimal constraint comprises a ball-and-socket joint.
19. The tool of claim 4 , wherein a pressure that said tool applies against the pins is adjustable.
20. The tool of claim 4 , configured to apply pressure against the pins by means of dead weight loading.
21. The tool of claim 1 , configured to receive dead weight loading.
22. The tool of claim 1 , configured as a collection of annular sub-tools arranged in a group.
23. A tool for lapping a wafer support surface of a wafer chuck, said surface comprising pins, said tool comprising:
(a) a surface configured to contact the pins of the wafer support surface of the wafer chuck, said contacting surface including a material of approximately equal or greater hardness than that of said pins, said contacting surface having a size that is larger in extent than a spacing between two adjacent pins of the wafer support surface;
(b) when contacted to a plane, said contacting surface making line contact with the plane, wherein said line contact consists of a circle;
(c) said contacting surface having a toroidal shape; and
(d) said contacting surface having a size that is less than a diameter of the wafer support surface.
24. The tool of claim 23 , wherein said contacting surface has a diameter of at least 3 millimeters.