High-performance single-photon pixel spad structure

Abstract

The invention discloses a high-performance single-photon pixel spad structure, and relates to the technical field of integrated circuits. The device comprises a silicon surface, a cathode and an anode, high voltage is applied to the cathode, and the anode is grounded; impurities with different properties are doped on the surface of silicon for multiple times, ions of N-type impurities and P-type impurities are injected with energy to form a plurality of back-to-back PN junctions, and finally the plurality of back-to-back PN junctions are connected in parallel; multiple times of doping are adopted, so that signals can be effectively led out from the deep part, and any two PN junctions are connected in parallel, so that the depth of a space depletion region is effectively increased in the longitudinal direction; the cathode and the deep N well injection are isolated from the P-type impurities by using epitaxial layer low-concentration doping; and the anode and the deep P well injection are isolated from the N-type impurities by using epitaxial layer low-concentration doping. According to the invention, the depth of the depletion region is effectively expanded, the detection efficiency is improved, and the diffusion time of photoelectrons is reduced, so that the time jitter is reduced, and the SPAD avalanche voltage can be effectively reduced.

Description

technical field [0001] The invention belongs to the technical field of integrated circuits, in particular to a high-performance single-photon pixel spad structure. Background technique [0002] The SPAD physical structure is a reverse PN junction. In the working state, it applies a high reverse bias voltage across the cathode N and the anode P, so that the diode works in Geiger mode. When photons are absorbed in its depletion region, the carrier multiplication effect occurs due to the high electric field strength, which instantly reduces the reverse resistance of the PN junction and generates a high reverse current. In the commonly used SPAD structure, the reverse bias voltage is above 15V, which makes it difficult for SPAD to be compatible with standard CMOS circuits. At the same time, high voltage requires strong isolation means, which leads to a huge single pixel size, which cannot improve the spatial resolution of detection. Seriously limit its application in tiny devic...

AI Technical Summary

Problems solved by technology

In the commonly used SPAD structure, the reverse bias voltage is above 15V, which makes it difficult for SPAD to be compatible with standard CMOS circuits. At the same time, high voltage requires strong isolation means, which leads to a huge single pixel size, which cannot improve the spatial resolution of detection. Seriously limit its application in tiny devices such as mobile phones

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