Method of making a deep junction for electrical crosstalk reduction of an image sensor

1. An image sensor semiconductor device, comprising:

a semiconductor substrate having a front surface and a back surface;

a plurality of sensor elements formed on the front surface of the substrate, each of the plurality of sensor elements configured to receive light directed towards the back surface; and

an aluminum doped feature formed in the substrate and extending from the back surface, but not extending to the front surface, the aluminum doped feature disposed horizontally between two adjacent elements of the plurality of sensor elements and vertically between the back surface and the plurality of sensor elements.

2. The device of claim 1 , wherein the aluminum doped feature comprises a depth/width ratio greater than about 3:1.

3. The device of claim 1 , wherein the substrate comprises a crystalline silicon configured in one of <100> and <111> orientation.

4. The device of claim 1 , wherein the aluminum doped feature comprises a height greater than about 1 micron.

5. The device of claim 1 , wherein the aluminum doped feature comprises an aluminum doping concentration ranging between about 10 13 atoms/cm 3 and 10 20 atoms/cm 3 .

6. The device of claim 1 , wherein each of the plurality of sensor elements is selected from the group consisting of complementary metal-oxide-semiconductor (CMOS) image sensor, charge-coupled device sensor, active pixel sensor, passive pixel sensor, and combinations thereof.

7. An image sensor semiconductor device, comprising:

a semiconductor substrate having a front surface and a back surface;

a sensor element formed in the semiconductor substrate;

an inter-level dielectric (ILD) formed on the front surface of the semiconductor substrate;

conductive features disposed in the ILD; and

a junction of aluminum dopants formed in the semiconductor substrate and extending from the back surface, but not extending to the front surface, the junction of aluminum dopants disposed horizontally around the sensor element in a top view of the semiconductor substrate.

8. The device of claim 7 , wherein the junction comprises a depth greater than 1 micron.

9. The device of claim 7 , wherein the junction of aluminum dopants comprises a doping profile with a ratio of depth/width greater than about 3:1.

10. The device of claim 7 , wherein the junction of aluminum dopants comprises an aluminum doping concentration ranging between about 10 13 atoms/cm 3 and 10 20 atoms/cm 3 .

11. An image sensor semiconductor device, comprising:

a substrate having a front surface and a back surface, the substrate including a crystalline silicon configured in one of <100> and <111> orientation;

a plurality of sensor elements formed at the front surface of the substrate, each of the plurality of sensor elements configured to receive light directed towards the back surface; and

an aluminum doped feature formed in the substrate and extending from the back surface, but not extending to the front surface, the aluminum doped feature disposed horizontally between two adjacent elements of the plurality of sensor elements and vertically between the back surface and the plurality of sensor elements,

wherein the crystalline silicon encourages the aluminum doped feature to form in the substrate at a vertical/horizontal ratio greater than about 3:1.

12. The device of claim 11 , wherein the aluminum doped feature comprises a height greater than about 1 micron.

13. The device of claim 11 , wherein the aluminum doped feature comprises an aluminum doping concentration ranging between about 10 13 atoms/cm 3 and 10 20 atoms/cm 3 .

14. The device of claim 11 , wherein each of the plurality of sensor elements is of a type selected from the group consisting of complementary metal-oxide-semiconductor (CMOS) image sensor, charge-coupled device sensor, active pixel sensor, passive pixel sensor, and combinations thereof.