Single photon avalanche diode and manufacturing method, detector array, and image sensor
View Patent ↗A single-photon avalanche diode and a manufacturing method thereof, a detector array, and an image sensor are disclosed. The back-side illuminated single-photon avalanche diode is disposed with a light-trapping structure and a sidewall reflection wall. Incident light is reflected, scattered, and refracted by the light-trapping structure and then dispersed to various angles, and with the addition of the reflection effect of the sidewall reflection wall, the effective optical path of the light in the back-side illuminated single-photon avalanche diode can be extended. The manufacturing method of a back-side illuminated single-photon avalanche diode achieves the manufacturing of the back-side illuminated single-photon avalanche diode. For the photoelectric detector array and the image sensor including the back-side illuminated single-photon avalanche diode, since they have the back side illumination single-photon avalanche diode, light absorption efficiencies of the photoelectric detector array and the image sensor are effectively improved.
1. A back-side illuminated (BSI) single-photon avalanche diode (SPAD) pixel circuit comprising:
a substrate material;
a first sidewall structure and a second sidewall structure;
a diffraction grating structure configured on the substrate material;
a first doped region overlaying the diffraction grating structure, the first doped region comprising a first top surface region and a second top surface region;
a second doped region overlaying the first top surface region of the first doped region, the second doped region comprising a third top surface region;
a third doped region overlaying the second top surface region of the first doped region and the third top surface region of the second doped region, the third doped region being positioned between the first sidewall structure and the second sidewall structure; and
a light-trapping structure overlaying the third doped region, the light-trapping structure comprising pyramid structures, the pyramid structures being horizontally aligned.
2. The circuit of claim 1 wherein the diffraction grating structure is configured to increase reflection of light wavelengths between 850 nm and 960 nm.
3. The circuit of claim 1 wherein the first doped region is characterized by a larger surface than the second doped region.
4. The circuit of claim 1 wherein the third doped region is characterized by a concentration gradient.
5. The circuit of claim 1 wherein the light-trapping structure comprises an anti-reflection structure configured to increase light absorption.
6. The circuit of claim 1 further comprising a SPAD region configured at a junction between the first doped region and the second doped region.
7. The circuit of claim 1 further comprising a silicon oxide layer configured between the diffraction grating structure and the substrate material.
8. The circuit of claim 1 further comprising a silicon oxide layer configured between the diffraction grating structure and the first doped region.
9. The circuit of claim 1 wherein the diffraction grating structure is substantially reflective.
10. The circuit of claim 1 wherein the light-trapping structure comprises diffraction grating elements.
11. The circuit of claim 1 wherein the first sidewall structure comprises a deep trench isolation structure.
12. The circuit of claim 1 wherein the first sidewall structure comprises a reflective surface.
13. The circuit of claim 1 further comprising a contact structure and a circuit layer configured within the substrate material.
14. A back-side illuminated (BSI) single-photon avalanche diode (SPAD) pixel circuit comprising:
a substrate material;
a first sidewall structure;
a diffraction grating structure configured on the substrate material;
a silicon oxide layer coupled to the diffraction grating structure;
a first doped region overlaying the diffraction grating structure, the first doped region comprising a first top surface region and a second top surface region;
a second doped region overlaying the first top surface region of the first doped region, the second doped region comprising a third top surface region;
a third doped region overlaying the second top surface region of the first doped region and the third top surface region of the second doped region; and
a light-trapping structure overlaying the third doped region, the light-trapping structure comprising pyramid structures, the pyramid structures being horizontally aligned.
15. The circuit of claim 14 , further comprising a SPAD region configured at a junction between the first doped region and the second doped region.
16. The circuit of claim 14 wherein the first sidewall structure comprises a deep trench isolation structure.
17. The circuit of claim 14 wherein the first sidewall structure is substantially reflective.