Back-illuminated Si photomultipliers: structure and fabrication methods

1. A back-illuminated silicon photomultiplier comprising:

a p-type substrate having front and back sides;

a matrix of n+ regions in the p-type substrate;

a matrix of p+ regions under the matrix of n+ regions

and adjacent the back side of the substrate, with the bottoms of the matrix of n+ regions each forming a p/n junction with the substrate or the respective p+ region;

a common anode formed by a uniform p++ deposition or implantation on the back side of the substrate; and,

cathode contacts coupled to each of the n+ regions.

2. The photomultiplier of claim 1 wherein the n+ regions extend from the front side of the substrate.

3. The photomultiplier of claim 1 wherein the n+ regions comprise a buried layer, and wherein cathode contacts to the n+ regions are made by vias from the front side of the substrate to the n+ regions.

4. The photomultiplier of claim 1 further comprising a plurality of trenches in the back side of the substrate between the n+ regions, the trenches being filled with an opaque material.

5. The photomultiplier of claim 1 wherein the substrate is a thin substrate.

6. The photomultiplier of claim 1 wherein the substrate is less than approximately 150 um thick.

7. The photomultiplier of claim 1 wherein a contact of the common anode is provided on the back side of the substrate.

8. The photomultiplier of claim 1 further comprising a through p++ diffusion, wherein a contact of the common anode is brought out to the front side of the p-type substrate, the through diffusion being made from at least one side of the substrate.

9. The photomultiplier of claim 1 further comprising a through p++ diffusion, wherein a contact of the common anode is brought out to the front side of the substrate the through diffusion being made from both sides of the substrate.

10. The photomultiplier of claim 1 wherein the p+ regions under the matrix of n+ regions are in contact with the n+ regions.

11. The photomultiplier of claim 1 wherein the p+ regions under the matrix of n+ regions are not in contact with the n+ regions.

12. The photomultiplier of claim 1 wherein the cathode contacts are coupled to each of the n+ regions through a resistive layer.

13. A back-illuminated silicon photomultiplier comprising:

a p-type substrate having front and back sides, and a thickness of less than approximately 150 um;

a matrix of n+ regions in the p-type substrate;

a matrix of p+ regions under the matrix of n+ regions

and adjacent the back side of the substrate, with the bottom of the matrix of n+ regions forming a p/n junction with the substrate or the p+ region;

a common anode formed by a uniform p++ deposition or implantation on the back side of the substrate;

a plurality of trenches in the back side of the substrate between the n+ regions, the trenches being filled with an opaque material; and

cathode contacts coupled to each of the n+ regions.

14. The photomultiplier of claim 13 wherein the n+ regions extend from the front side of the substrate.

15. The photomultiplier of claim 13 wherein the n+ regions comprise a buried layer, and wherein the cathode contacts to the n+ regions are made by vias from the front side of the substrate to the n+ regions.

16. The photomultiplier of claim 13 wherein a contact of the common anode is provided on the back side of the substrate.

17. The photomultiplier of claim 13 further comprising at least one through p++ diffusion, wherein a contact of the common anode is brought out to the front side of the p-type substrate, the through diffusion being made from one side of the substrate.

18. The photomultiplier of claim 13 further comprising at least one through p++ diffusion, wherein a contact of the common anode is brought out to the front side of the p-type substrate, the through diffusion being made from both sides of the substrate.

19. The photomultiplier of claim 13 wherein the p+ regions under the matrix of n+ regions are in contact with the matrix of n+ regions.

20. The photomultiplier of claim 13 wherein the p+ regions under the matrix of n+ regions are not in contact with the matrix of n+ regions.

21. The photomultiplier of claim 13 where the p+ regions are ion implanted regions.

22. The photomultiplier of claim 13 wherein the cathode contacts are coupled to each of the n+ regions through a resistive layer.

23. A back-illuminated silicon photomultiplier comprising:

a substrate of a first conductivity type having front and back sides, and a thickness of less than approximately 150 um;

a matrix of regions of a second conductivity type in the substrate;

a matrix of regions of the first conductivity type under the matrix of regions of the second conductivity type and adjacent the back side of the substrate, with the bottom of the matrix of regions of the second conductivity type forming a p/n junction with the substrate or the matrix of regions of the first conductivity type, the matrix of regions of the first conductivity type having a higher conductivity than the substrate; a common anode formed by a uniform layer of the first conductivity type of higher conductivity than the substrate on the back side of the substrate; a plurality of trenches in the back side of the substrate between the second conductivity type regions, the trenches being filled with an opaque material; and cathode contacts coupled to each of the regions of the second conductivity type.

24. The photomultiplier of claim 23 wherein the matrix of regions of the second conductivity type extend from the front side of the substrate.

25. The photomultiplier of claim 23 wherein the matrix of regions of the second conductivity type comprise a buried layer, and wherein the cathode contacts to the matrix of regions of the second conductivity type are made by vias from the front side of the substrate to the matrix of regions of the second conductivity type.

26. The photomultiplier of claim 23 wherein a contact of the common anode is provided on the back side of the substrate.

27. The photomultiplier of claim 23 further comprising at least one through diffusion of the first conductivity type and of a higher conductivity than the substrate, wherein a contact of the common anode is brought out to the front side of the substrate, the through diffusion being made from one side of the substrate.

28. The photomultiplier of claim 23 further comprising at least one through diffusion of the first conductivity type, wherein a contact of the common anode is brought out to the front side of the substrate of a first conductivity type, the through diffusion being made from both sides of the substrate.

29. The photomultiplier of claim 23 wherein the matrix of regions of the first conductivity type under the matrix of regions of the second conductivity type are in contact with the matrix of regions of the second conductivity type.

30. The photomultiplier of claim 23 wherein the matrix of regions of the first conductivity type under the matrix of regions of the second conductivity type are not in contact with the matrix of regions of the second conductivity type.

31. The photomultiplier of claim 23 wherein the matrix of regions of the first conductivity type under the matrix of regions of the second conductivity type are ion implanted regions.

32. The photomultiplier of claim 23 wherein the cathode contacts are coupled to each of the regions of the second conductivity type through a resistive layer.