The invention discloses a
CMOS APD photoelectric device with low
dark current, and belongs to the field of
semiconductor photoelectric devices. The device structure comprises a P substrate and further comprises a P trap which is subjected to
ion implantation on the P substrate, an N+ layer and two P+
layers are subjected to
ion implantation on the P trap, the N+ layer is a
cathode, and the P+
layers are anodes. The heavily doped N+ layer and the lightly doped P well layer form a PN junction, namely an avalanche region is formed, an illumination window is arranged, when a
light source is emitted into the device and absorbed by the light absorption region,
photon-generated carriers are generated, and the
photon-generated carriers move to the avalanche region under the action of an
electric field to participate in multiplication; STI protection rings are doped at the two ends of the gap of the P well layer, small-size STI protection rings are doped at the two sides of the N + layer, and due to reasonable arrangement of STI, reduction of
dark current can be guaranteed, and
photocurrent can be effectively detected; and the
photoelectric effect and the
capacitance are optimized on the design of the device
electrode. The
design technology is designed from three aspects of PN junction, STI
protection ring and
electrode arrangement, so the
dark current of the device is reduced, it is ensured that the
photocurrent can be detected, and the
capacitance is reduced.