System, method and apparatus for multi-beam lithography including a dispenser cathode for homogeneous electron emission
View Patent ↗A dispenser cathode which comprises an emission surface, a reservoir for material releasing, when heated, work-function-lowering particles, and at least one passage for allowing diffusion of work-function-lowering particles from said reservoir to said emission surface, said emission surface comprising at least one emission area and at least one non-emission area covered with emission-suppressing material and surrounding each emission area, said non-emission area comprising at least one passage connecting said reservoir with said non-emission area and debouching within a diffusion length distance from an emission area for allowing diffusion of work-function-lowering particles from said reservoir to said emission area.
1. A dispenser cathode which comprises:
an emission surface comprising at least one emission area for emitting electrons and at least one non-emission area covered with emission-suppressing material and surrounding each emission area;
a reservoir for material releasing, when heated, work-function-lowering particles;
at least one passage connecting said reservoir and said emission surface for allowing diffusion of work-function-lowering particles from said reservoir to said emission surface,
wherein the non-emission area is a concave or cone-shaped wall surrounding the emission area, wherein the wall is coated with, or made of, an emission suppressing material and wherein the wall is arranged for providing a lens effect.
2. The dispenser cathode of claim 1 , wherein said at least one passage for said work-function-lowering particles debouching adjacent the emission area.
3. The dispenser cathode of claim 1 , wherein said at least one passage surrounds the emission area.
4. The dispenser cathode of claim 1 , wherein said at least one passage surround the entire emission area.
5. The dispenser cathode of claim 1 , furthermore provided with a support structure for supporting said emission area.
6. The dispenser cathode of claim 5 , wherein said support structure comprises a pillar at the location of said emission area and reaching through said reservoir.
7. The dispenser cathode of claim 6 , wherein said pillar has a top forming part of said emission surface.
8. The dispenser cathode of claim 7 , wherein the top of said pillar forms an emission area.
9. The dispenser cathode of claim 6 , wherein said passage runs along a side of said pillar.
10. The dispenser cathode of claim 9 , wherein said passage surrounds the entire pillar.
11. The dispenser cathode of claim 9 , wherein said pillar has a sidewall, said sidewall providing a wall of a passage.
12. The dispenser cathode of claim 1 , wherein said emission area merges into said wall.
13. An electron source for generating a plurality of electron beams, comprising a plurality of dispenser cathodes according to claim 1 .
14. A lithography system comprising at least one dispenser cathode of claim 1 .
15. A semiconductor wafer, processed using a lithography system according to claim 14 .
16. A method for processing a semiconductor wafer, using a lithography system according to claim 14 .
17. The dispenser cathode of claim 1 , wherein the lens effect renders a narrowed beam.
18. The dispenser cathode of claim 1 , wherein the angle P of the wall is between 20-25 degrees.
19. The dispenser cathode of claim 1 , wherein the wall is coated or made of conducting material.
20. The dispenser cathode of claim 6 , wherein said pillar is arranged central to said wall and at a distance from said wall.
21. The dispenser cathode of claim 7 , wherein the top of said pillar is located below the level of the surface of the dispenser cathode.
22. The dispenser cathode of claim 21 , wherein the top of said pillar is located in a recess in said surface of the dispenser.
23. The dispenser cathode of claim 6 , wherein an edge part of said pillar intersects the projection of said wall.
24. The dispenser cathode of claim 12 , wherein the at least one passage is arranged at the transition from said emission area into said wall.
25. The dispenser cathode of claim 1 , wherein the emission surface is a circular area.
26. A dispenser cathode which comprises an emission surface comprising at least one emission area for emitting electrons and at least one non-emission area covered with emission-suppressing material and surrounding each emission area, wherein the non-emission area comprises a concave or cone-shaped wall surrounding the emission area, which wall is coated with, or made of, emission suppressing material, and wherein the wall is arranged for providing a lens effect.
27. The dispenser cathode of claim 26 , wherein the lens effect renders a narrowed beam.
28. The dispenser cathode of claim 26 , wherein the angle P of the wall is between 20-25 degrees.
29. The dispenser cathode of claim 26 , wherein the wall is coated or made of conducting material.
30. The dispenser cathode of claim 26 , wherein the emission surface is arranged on a pillar, and said pillar is arranged central to said wall and at a distance from said wall.
31. The dispenser cathode of claim 30 , wherein the top of said pillar is located below the level of the surface of the dispenser cathode.
32. The dispenser cathode of claim 30 , wherein the top of said pillar is located in a recess in said surface of the dispenser.
33. The dispenser cathode of claim 30 , wherein an edge part of said pillar intersects the projection of said wall.
34. The dispenser cathode of claim 26 , wherein holes are made all the way to a reservoir with work-function-lowering particles, and wherein said holes are arranged at the transition from said emission area into said wall.
35. The dispenser cathode of claim 26 , wherein the emission surface is a circular area.