CMOS (complementary metal oxide semiconductor) image sensor column shared pixel unit and pixel array

Abstract

The invention discloses a CMOS (complementary metal oxide semiconductor) image sensor column shared pixel unit and a pixel array. One group of pixel unit is formed by two column pixels; each two corresponding pixels share a selective transistor, a source tracking transistor, a reset transistor and a floating active area in the column; a plurality of groups of pixel units are arranged in the vertical and horizontal directions to form a two-dimensional pixel array; in the two-dimensional pixel array, two layers of metal connecting wires are used for connection; only the 0th layer of metal connecting wires and the first layer of metal connecting wires in the metal connecting wires are used as control lines of a device to implement a function of acquiring image information and the second layer or the higher layer of metal connecting wires are not used as the control lines of the device; and the medium height on a Si surface of a photodiode can be reduced, so that more light enters the photodiode and the light utilizing efficiency and the conversion gain of a small-area pixel sensor can be improved, and thus, the sensitivity is improved and the image quality of the small-area pixel sensor can be effectively improved.

Description

technical field [0001] The invention relates to a CMOS image sensor, in particular to a column sharing pixel unit and a pixel array of a CMOS image sensor. Background technique [0002] Image sensors are already widely used in digital cameras, mobile phones, medical devices, automobiles and other applications. In particular, the rapid development of CMOS (Complementary Metal Oxide Semiconductor) image sensors has made people have higher requirements for low power consumption, small size, and high resolution image sensors. [0003] The pixel structure arrangement of CMOS image sensors in the prior art takes 4T2S (four transistors and two pixels shared) as an example. Due to the dependence on the structural characteristics of the pixel itself, the pixel array generally requires the first layer of metal, and the second layer of metal and the third layer of metal are used as device interconnection lines, and multiple rows or columns of the first layer of metal, the second layer...

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Problems solved by technology

[0005] Due to the small photosensitive area and low sensitivity of the small-area pixel sensor, the information transmitted in dark light is not clear enough

Especially when the first layer of metal, the second layer of metal and the third layer of metal are used as device interconnection lines, the dielectric height on the surface of the photodiode Si (silicon) is relatively high, and the metal connection blocks part of the light from entering the photodiode ; Moreover, the metal connection between the floating active region and the gate of the source follower transistor is close to the power metal connection, and the parasitic capacitance of the floating active region is large, resulting in a small amplitude (conversion gain) for converting signal electrons into signal voltage

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