Method to planarize three-dimensional structures to enable conformal electrodes

1. A method, comprising:

forming a 3-dimentional (3-D) structure comprising a first layer and an array of pillars with cavity regions between said pillars, wherein each pillar of said pillars comprises a first end and a second end, wherein said first end is in contact with said first layer, wherein said first layer comprises only one of n material or p material, wherein each said pillar comprises an intrinsic material;

forming a segment on said second end of each said pillar, wherein said segment comprises said p material if said first layer comprises said n material and wherein said segment comprises said n material if said first layer comprises said p material;

filling said cavity regions with a fill material, wherein said fill material covers each said segment;

removing a first portion of said fill material to produce an exposed portion of said segment;

simultaneously depositing an electrode onto said fill material and each said exposed segment, thereby forming a conductive layer that provides a common contact to each said exposed segment; and

depositing a second electrode on said first layer.

2. The method of claim 1 , wherein said fill material comprises a support material for supporting said pillars.

3. The method of claim 2 , further comprising spin coating said support material into said cavity regions.

4. The method of claim 2 , wherein said support material is selected from the group consisting of a photoresist, a polymer and a dielectric.

5. The method of claim 1 , wherein said fill material comprises a functional material.

6. The method of claim 5 , wherein the step of filling said cavity regions comprises depositing said functional material into said cavity regions.

7. The method of claim 6 , wherein said functional material comprises a neutron sensitive material.

8. The method of claim 7 , wherein said neutron sensitive material comprises a length sufficient to absorb neutrons propagating along the long aspect of any said cavity region.

9. The method of claim 6 , wherein said neutron sensitive material is selected from the group consisting of lithium fluoride, gadolinium and boron.

10. The method of claim 5 , wherein said pillars are separated by less than the range of a mean free path of a charged particle produced within said functional material.

11. The method of claim 5 , wherein each cavity region of said cavity regions comprises a diameter that is less than the range of at least one neutron reaction-produced particle produced within said functional material.

12. The method of claim 1 , wherein said 3-D structure comprises Si.

13. The method of claim 1 , wherein each said pillar comprises an aspect ratio within a range from greater than 5 to less than 500.

14. The method of claim 1 , wherein between the step of removing a portion of said fill material and the step of simultaneously depositing an electrode, said method further comprises:

depositing a sacrificial layer over said fill material and said exposed portion; and

etching back said sacrificial layer to expose at least part of said exposed portion.

15. The method of claim 1 , wherein the step of removing a portion of said fill material to produce an exposed portion of said segment comprises:

depositing a sacrificial layer over said fill material;

etching back said sacrificial layer to about said fill material; and

etching back a portion of said fill material to produce an exposed portion of said segment do this later in claims too.

16. The method of claim 15 , wherein said fill material comprises an etch rate that is faster than that of said sacrificial layer.

17. The method of claim 1 , wherein the removing a portion of said fill material to produce an exposed portion of said segment comprises:

depositing a sacrificial layer over said fill material; and

etching back said sacrificial layer and said fill material to produce an exposed portion of said segment.

18. The method of claim 17 , wherein said fill material comprises an etch rate that is substantially the same as that of said sacrificial layer.

19. The method of claim 1 , wherein the step of removing a portion of said fill material to produce an exposed portion of said segment comprises etching back a portion of said fill material to produce an exposed portion of said segment.

20. The method of claim 1 , wherein the step of removing a portion of said fill material to produce an exposed portion of said segment comprises lapping a portion of said fill material to produce an exposed portion of said segment.

21. A method, comprising:

forming a 3-dimentional (3-D) structure comprising a first layer and an array of pillars with cavity regions between said pillars, wherein each pillar of said pillars comprises a first end and a second end, wherein said first end is in contact with said first layer, wherein said first layer comprises only one of an n material or a p material, wherein each said pillar comprises an intrinsic material;

forming a segment on said second end of each said pillar, wherein said segment comprises said p material if said first layer comprises said n material and wherein said segment comprises said n material if said first layer comprises said p material;

filling said cavity regions with a fill material, wherein said fill material covers each said segment;

removing a first portion of said fill material to produce an exposed portion of said segment, wherein said first portion is removed by a method selected from the group consisting of etching back said first portion and lapping said first portion;

depositing a sacrificial layer over said fill material and said exposed portion;

etching back said sacrificial layer to expose at least part of said exposed portion;

simultaneously depositing an electrode onto said fill material and at least part of each said exposed segment, thereby forming a conductive layer that provides a common contact to each said exposed segment; and

depositing a second electrode on said first layer.

22. A method, comprising:

forming a 3-dimentional (3-D) structure comprising a first layer and an array of pillars with cavity regions between said pillars, wherein each pillar of said pillars comprises a first end and a second end, wherein said first end is in contact with said first layer, wherein said first layer comprises only one of an n material or a p material, wherein each said pillar comprises an intrinsic material;

forming a segment on said second end of each said pillar, wherein said segment comprises said p material if said first layer comprises said n material and wherein said segment comprises said n material if said first layer comprises said p material;

filling said cavity regions with a fill material, wherein said fill material covers each said segment;

depositing a sacrificial layer over said fill material;

etching back said sacrificial layer to about said fill material;

etching back a portion of said fill material to produce an exposed portion of said segment;

removing any remaining sacrificial material in contact with said fill material;

simultaneously depositing an electrode onto said fill material and each said exposed segment, thereby forming a conductive layer that provides a common contact to each said exposed segment; and

depositing a second electrode on said first layer.

23. The method of claim 22 , wherein said fill material comprises an etch rate that is faster than that of said sacrificial layer.

24. A method, comprising:

forming a 3-dimentional (3-D) structure comprising a first layer and an array of pillars with cavity regions between said pillars, wherein each pillar of said pillars comprises a first end and a second end, wherein said first end is in contact with said first layer, wherein said first layer comprises only one of an n material or a p material, wherein each said pillar comprises an intrinsic material;

forming a segment on said second end of each said pillar, wherein said segment comprises said p material if said first layer comprises said n material and wherein said segment comprises said n material if said first layer comprises said p material;

filling said cavity regions with a fill material, wherein said fill material covers each said segment;

depositing a sacrificial layer over said fill material;

etching back said sacrificial layer and said fill material to produce an exposed portion of said segment;

simultaneously depositing an electrode onto said fill material and each said exposed segment, thereby forming a conductive layer that provides a common contact to each said exposed segment; and

depositing a second electrode on said first layer.

25. The method of claim 24 , wherein said fill material comprises an etch rate that is substantially the same as that of said sacrificial layer.

26. An apparatus, comprising:

a 3-dimentional (3-D) structure comprising a first layer and an array of pillars with cavity regions between said pillars, wherein each pillar of said pillars comprises a first end and a second end, wherein said first end is in contact with said first layer, wherein said first layer comprises only one of an n material or a p material, wherein each said pillar comprises an intrinsic material;

a segment on said second end of each said pillar, wherein said segment comprises said p material if said first layer comprises said n material and wherein said segment comprises said n material if said first layer comprises said p material;

fill material located in said cavity regions;

an exposed portion of said segment;

an electrode on said fill material and each said exposed segment, thereby forming a conductive layer that provides a common contact to each said exposed segment; and

a second electrode on said first layer.

27. The apparatus of claim 26 , wherein said fill material comprises a support material for supporting said pillars.

28. The apparatus of claim 27 , wherein said neutron sensitive material comprises a length sufficient to absorb neutrons propagating along the long aspect of any said cavity region.

29. The apparatus of claim 26 , wherein said fill material comprises a functional material.

30. The apparatus of claim 29 , wherein said functional material comprises a neutron sensitive material.

31. The apparatus of claim 30 , wherein said neutron sensitive material is selected from the group consisting of lithium fluoride, gadolinium and boron.

32. The apparatus of claim 26 , wherein said 3-D structure comprises Si.

33. The apparatus of claim 26 , wherein each said pillar comprises an aspect ratio within a range from greater than 5 to less than 500.

34. The apparatus of claim 26 , wherein each said pillar comprises an aspect ratio within a range from about 10:1 to about 100:1.

35. The apparatus of claim 26 , wherein each said pillar comprises an aspect ratio of about 25:1.

36. The apparatus of claim 26 , wherein said pillars are separated by less than the range of a mean free path of a charged particle produced within said functional material.

37. The apparatus of claim 26 , wherein each said pillar comprises a diameter of about 2 microns.

38. The apparatus of claim 26 , wherein each cavity region of said cavity regions comprises a diameter of about 2 microns.

39. The apparatus of claim 26 , wherein each cavity region of said cavity regions comprises a diameter that is less than the range of at least one neutron reaction-produced particle produced within said functional material.

40. The apparatus of claim 26 , further comprising a sacrificial layer in said cavity between said fill material and said first electrode.