Photodiode having increased proportion of light-sensitive area to light-insensitive area
View Patent ↗A photodiode having an increased proportion of light-sensitive area to light-insensitive area includes a semiconductor having a backside surface and a light-sensitive frontside surface. The semiconductor includes a first active layer having a first conductivity, a second active layer having a second conductivity opposite the first conductivity, and an intrinsic layer separating the first and second active layers. A plurality of isolation trenches are arranged to divide the photodiode into a plurality of cells. Each cell has a total frontside area including a cell active frontside area sensitive to light and a cell inactive frontside area not sensitive to light. The cell active frontside area forms at least 95 percent of the cell total frontside area. A method of forming the photodiode is also disclosed.
1. A photodiode having an increased proportion of light-sensitive area to light-insensitive area comprising:
a semiconductor having a backside surface and a light-sensitive frontside surface and including:
a first active layer having a first conductivity,
a second active layer having a second conductivity opposite the first conductivity, and
an intrinsic layer separating the first and second active layers; and
a plurality of isolation trenches arranged to divide the photodiode into a plurality of cells, each cell having a total frontside area including a cell active frontside area sensitive to light and a cell inactive frontside area not sensitive to light, and the cell active frontside area forming at least 95 percent of the cell total frontside area.
2. The photodiode of claim 1 , wherein:
the isolation trenches together define a trench inactive frontside area;
the frontside surface of the semiconductor has a total area including a semiconductor active area equal to the sum of each cell active frontside area and a semiconductor inactive area including each cell inactive frontside area and the trench inactive frontside area; and
the semiconductor active area forms at least 90 percent of the semiconductor total area.
3. The photodiode of claim 1 , wherein each cell includes a via having a via frontside area forming a portion of the cell inactive frontside area and a frontside electrical contact having a electrical contact frontside area also forming a portion of the cell inactive frontside area.
4. The photodiode of claim 3 , wherein the electrical contact frontside area is less than 4 percent of the cell total frontside area.
5. The photodiode of claim 3 , wherein the via frontside area is less than 2 percent of the cell total frontside area.
6. The photodiode of claim 3 , wherein each via has a ratio of a length of the via to a diameter of the via equal to at least 7.0.
7. The photodiode of claim 3 , wherein the frontside electrical contact has a length in a direction substantially parallel to the frontside surface and extending between the via and a connection to the second active layer, the length being no greater than three times a diameter of the via.
8. The photodiode of claim 1 , wherein each isolation trench has a ratio of a depth of the isolation trench to a width of the isolation trench equal to at least 5.0.
9. The photodiode of claim 1 , further comprising at least one cathode contact pad and at least one anode contact pad positioned on the semiconductor backside surface.
10. The photodiode of claim 1 , wherein the first conductivity is one of p-type and n-type, and the second conductivity is the other one of p-type and n-type.
11. The photodiode of claim 1 , wherein the first active layer is one of cathodic and anodic and the second active layer is the other one of cathodic and anodic.
12. The photodiode of claim 1 , wherein each isolation trench is substantially linear in shape along the depth of the trench and has a longitudinal axis extending in a direction of the depth.
13. The photodiode of claim 12 , wherein the isolation trench longitudinal axes are substantially perpendicular to the frontside surface.