SINGLE PHOTON AVALANCHE DIODE FOR CMOS CIRCUITS

摘要

A single photon avalanche diode (400) is disclosed, for use in a CMOS integrated circuit, the single photon avalanche diode, SPAD, comprising: a deep n-well region (406) formed above a p-type substrate (402); an n-well region (408) formed above and in contact with the deep n-well region (406); a cathode contact (412) connected to the n-well region (408) via a heavily doped n-type implant (410); a lightly doped region (428) forming a guard ring around the n-well and deep n-well regions; a p-well region (416, 422) adjacent to the lightly doped region; and an anode contact (420, 426) connected to the p-well region via a heavily doped p-type implant (418, 424); the junction (414) between the bottom of the deep n-well region and the substrate forming a SPAD multiplication region when an appropriate bias voltage is applied between the anode and cathode and the guard ring breakdown voltage being controlled with appropriate control of the lateral doping concentration gradient such that the breakdown voltage is higher than that of the planar SPAD multiplication region.