Single-photon avalanche diodes with hybrid trench isolation structures

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

• a semiconductor substrate having a top surface and a first doped region adjacent to the top surface of the semiconductor substrate;
• a semiconductor layer on the top surface of the semiconductor substrate, the semiconductor layer having a top surface and a first trench extending from the top surface of the semiconductor layer fully through the semiconductor layer to a first depth in the semiconductor substrate, and the first trench has a first sidewall and a second sidewall;
• a cathode including a portion of the first doped region in the semiconductor substrate;
• an anode including a second doped region adjacent to the top surface of the semiconductor layer;
• a first trench isolation structure inside the first trench, the first trench isolation region including a first conductor layer and a first dielectric layer extending from the top surface of the semiconductor layer through the semiconductor layer to the portion of the first doped region, the first dielectric layer having a first section on the first sidewall and a second section on the second sidewall, the first conductor layer is positioned between the first section of the first dielectric layer and the second section of the first dielectric layer, and the first conductor layer of the first trench isolation structure is electrically and physically connected to the portion of the first doped region;
• and
• a second trench isolation structure adjacent to the first trench isolation structure, the second trench isolation structure including a second conductor layer extending from the top surface of the semiconductor layer fully through the first doped region.