Deep trench isolation structures for a single-photon avalanche diode

1 . A structure for a single-photon avalanche diode, the structure comprising:

a semiconductor substrate having a top surface;

a semiconductor layer on the top surface of the semiconductor substrate;

a light-absorbing layer on a first portion of the semiconductor layer;

a dielectric layer on a second portion of the semiconductor layer;

a first doped region in the semiconductor substrate adjacent to the semiconductor layer; and

a deep trench isolation structure that penetrates through the dielectric layer and the second portion of the semiconductor layer to the first doped region, the deep trench isolation structure including a conductor layer and a dielectric liner, the dielectric liner including a first portion between the conductor layer and the semiconductor layer, and the conductor layer connected to the first doped region.

2 . The structure of claim 1 wherein the conductor layer of the deep trench isolation structure has a top surface, the light-absorbing layer has a top surface, and the top surface of the conductor layer is substantially coplanar with the top surface of the light-absorbing layer.

3 . The structure of claim 2 wherein the dielectric layer has a top surface, and the top surface of the dielectric layer is substantially coplanar with the top surface of the light-absorbing layer.

4 . The structure of claim 1 wherein the dielectric layer has a top surface, and further comprising:

an interlayer dielectric layer on the top surface of the dielectric layer;

a first contact that penetrates through the interlayer dielectric layer to the conductor layer; and

a second contact that penetrates through the interlayer dielectric layer to the light-absorbing layer.

5 . The structure of claim 4 wherein the first contact is disposed fully above the top surface of the dielectric layer.

6 . The structure of claim 4 wherein the first contact has a first height, and the second contact has a second height that is substantially equal to the first height.

7 . The structure of claim 6 wherein the interlayer dielectric layer has a thickness, and the first height is equal to the thickness.

8 . The structure of claim 6 wherein the interlayer dielectric layer has a thickness, and the second height is substantially equal to the thickness.

9 . The structure of claim 4 further comprising:

a second doped region having a first portion in the light-absorbing layer,

wherein the second contact is coupled to the second doped region, the first doped region is a cathode of the single-photon avalanche diode, and the second doped region is an anode of the single-photon avalanche diode.

10 . The structure of claim 9 wherein the light-absorbing layer comprises a first material, and further comprising:

a cap layer on the light-absorbing layer, the cap layer comprising a second material different from the first material,

wherein the second doped region has a second portion in the cap layer, and the second contact adjoins the cap layer.

11 . The structure of claim 4 further comprising:

a silicide layer on the conductor layer of the deep trench isolation structure, the silicide layer disposed between the first contact and the conductor layer.

12 . The structure of claim 1 wherein the deep trench isolation structure includes a first portion that fully surrounds the light-absorbing layer.

13 . The structure of claim 12 wherein the deep trench isolation structure includes a second portion that fully surrounds the first portion and the second portion of the semiconductor layer.

14 . The structure of claim 1 wherein the deep trench isolation structure includes a trench that extends through the conductor layer and the dielectric layer to a portion of the first doped region, and the conductor layer is disposed inside the trench.

15 . The structure of claim 1 wherein the dielectric liner includes a second portion disposed between the conductor layer and the dielectric layer.

16 . The structure of claim 1 wherein the dielectric layer has a top surface, and the deep trench isolation structure is positioned between the top surface of the semiconductor substrate and the top surface of the dielectric layer.

17 . The structure of claim 1 wherein the semiconductor layer has a first thickness, the dielectric layer has a second thickness, and the deep trench isolation structure has a height that is substantially equal to a sum of the first thickness and the second thickness.

18 . The structure of claim 1 wherein the light-absorbing layer comprises a semiconductor material.

19 . The structure of claim 1 wherein the conductor layer comprises doped polysilicon, metal, or a combination of doped polysilicon and metal.

20 . A method of forming a structure for a single-photon avalanche diode, the method comprising:

forming a semiconductor layer on a top surface of a semiconductor substrate;

forming a light-absorbing layer on a first portion of the semiconductor layer;

forming a dielectric layer on a second portion of the semiconductor layer;

forming a doped region in the semiconductor substrate adjacent to the semiconductor layer; and

forming a deep trench isolation structure that penetrates through the dielectric layer and the second portion of the semiconductor layer to the doped region, wherein the deep trench isolation structure includes a conductor layer and a dielectric liner including a portion between the conductor layer and the semiconductor layer, and the conductor layer is connected to the doped region.