Bonding fixture
A bonding fixture. In some embodiments, the fixture includes: a plate for supporting a central region of the wafer, the central region including 80% of the area of the wafer; and a frame for supporting: the edge of the wafer, and the edge of the plate, the frame having: a first vacuum passage, for pulling the wafer against an upper surface of the frame, and a second vacuum passage, for pulling the plate against the frame.
1. A fixture for holding a wafer, the fixture comprising:
a plate for supporting a central region of the wafer, the central region including 80% of an area of the wafer; and
a frame for supporting:
an edge of the wafer, and
an edge of the plate,
the frame having:
a first vacuum passage, for pulling the wafer against an upper surface of the frame, and
a second vacuum passage, for pulling the plate against the frame,
wherein the plate is shaped and sized such that an uppermost surface of the plate is lower than an uppermost surface of the frame when the plate is supported by the frame.
2. The fixture of claim 1 , wherein the fixture further comprises a third vacuum passage, for pulling the wafer against the plate.
3. The fixture of claim 2 , wherein the third vacuum passage is in fluid communication with a groove in the plate.
4. The fixture of claim 3 , wherein the groove in the plate is a straight, diametrical groove in a surface of the plate facing the wafer.
5. The fixture of claim 2 , wherein the plate fits into a recess in the frame, a lower surface of the plate abutting against a shelf at the bottom of the recess.
6. The fixture of claim 5 , wherein the third vacuum passage is connected to a hole in a wall of the recess.
7. The fixture of claim 5 , wherein the second vacuum passage is for pulling the plate against the shelf, and the second vacuum passage is connected to a hole in the shelf.
8. The fixture of claim 5 , wherein the shelf is flat to within 5 microns.
9. The fixture of claim 1 , wherein the upper surface of the plate is below the upper surface of the frame by at most 30 microns.
10. The fixture of claim 1 , wherein the upper surface of the frame is flat to within 5 microns.
11. The fixture of claim 1 , wherein the first vacuum passage is connected to a hole in the upper surface of the frame.
12. The fixture of claim 1 , wherein the frame is composed of metal.
13. The fixture of claim 12 , wherein the frame is composed of stainless steel.
14. The fixture of claim 1 , wherein the plate is transparent at a wavelength between 0.8 micron and 11 microns.
15. The fixture of claim 14 , wherein the plate is composed of borosilicate glass.
16. The fixture of claim 1 , wherein the plate has a thickness of between 2 mm and 12 mm.
17. A fixture for holding a wafer, the fixture comprising:
a plate for supporting a central region of the wafer, the central region including 80% of an area of the wafer; and
a frame for supporting:
an edge of the wafer, and
an edge of the plate,
the frame having:
a first vacuum passage, for pulling the wafer against an upper surface of the frame, and
a second vacuum passage, for pulling the plate against the frame,
wherein the frame has a recess defined at least in part by a bottom shelf and by a sidewall, the sidewall being connected between the bottom shelf and the upper surface of the frame, and
wherein the fixture further comprises a third vacuum passage that is connected to a hole in the sidewall.