The invention relates to a
CMOS SPAD photoelectric device with a deep N well in reverse
doping distribution. The
CMOS SPAD photoelectric device comprises a P substrate, the deep N well, a central N well and a P + layer are arranged on the P substrate, N wells are arranged at the two sides of the deep N well, the deep N well is of a reverse
doping distribution structure, namely, the concentration of the deep N well close to the surface of the device is low, and the concentration of the deep N well is higher with the longitudinal depth away from the surface of the device is increased, transverse
diffusion exists between the N wells at the two sides in the deep N well and the central N well, an n-virtual
protection ring is formed at the edge of the PN junction, when incident photons are emitted into the device and are mainly absorbed by the deep N well, most photons can be utilized by the P + layer / central N well junction to form
photon-generated carriers, and only a small number of photons penetrate through the deep N well to form a
photon-generated carrier on the P substrate. The
photon detection efficiency of the device is improved mainly from two aspects of increasing the thickness of the absorption region of the device and optimizing the
quantum efficiency of the device.