Novel CMOS image sensor pixel structure

Abstract

The invention provides a novel CMOS image sensor pixel structure. The novel CMOS image sensor pixel structure comprises a photodiode, a floating diffusion node, a reset transistor and a transfer transistor, wherein the photodiode is of a hollow annular structure, the floating diffusion node is arranged in a hollow area of the photodiode, the transfer transistor is of an annular structure, the inner edge of the transfer transistor is in contact with the floating diffusion node, the outer edge of the transfer transistor is in contact with the photodiode, and the reset transistor is arranged under the floating diffusion node. Charges accumulated by the photodiode are transferred from different directions to the floating diffusion node through the transfer transistor, a vertical electric field is provided through the reset transistor, and the floating diffusion node is reset. The area of the photosensitive region of the photodiode can be increased under the condition that the charge transfer speed of the transfer transistor is not influenced.

Description

technical field [0001] The invention relates to the technical field of CMOS image sensors, in particular to a CMOS image sensor pixel structure based on a ring photosensitive element. Background technique [0002] CMOS image sensors are becoming more and more popular in scientific and commercial applications due to their low power consumption, low cost and high integration capability. With the continuous expansion of the application range of CMOS image sensors, people have higher requirements for their performance, and they are constantly developing towards higher resolution, wider dynamic range, and faster speed. Generally, for an image sensor with the same resolution, the larger the photosensitive area, the better the imaging quality. For the optical format attribute of the camera, the imaging quality of 2 / 3" is better than that of 1 / 2" in most conditions, especially in low-light environments. Therefore, how to increase the area of ​​the photosensitive unit of the image ...

AI Technical Summary

Problems solved by technology

[0005] The present invention aims to solve the problem of image smear caused by directly increasing the area of ​​the photosensitive region of the traditional CMOS image sensor, and provides a new CMOS image sensor pixel structure, which can increase the photoelectricity without affecting the charge transfer speed of the transfer transistor. The area of ​​the photosensitive region of the diode

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