CMOS image sensor pixel unit

Abstract

The invention discloses a CMOS image sensor pixel unit. Because a signal output line, a control line and a power line which are made of same metal are adopted in a dielectric layer and distributed on the same dielectric layer above the rows or columns of photosensitive elements of pixel arrays in a staggering and bridging mode, the thickness of the dielectric layer is remarkably reduced, and therefore loss caused before incident light reaches the photosensitive elements is reduced, the sensitivity of the pixel unit is effectively improved; light shielding rings are arranged around the photosensitive elements, optical crosstalk between the pixel units is effectively prevented, and due to the use of an image sensor, high-quality images can be obtained under a low-illumination condition.

Description

technical field [0001] The invention relates to the field of image sensors, in particular to a pixel unit of a CMOS image sensor capable of realizing high sensitivity. Background technique [0002] Image sensors are devices that convert light signals into electrical signals. Image sensors generally include charge-coupled device (CCD) and complementary metal-oxide-semiconductor (CMOS) image sensor chips. Compared with traditional CCD sensors, CMOS image sensors are more and more widely used because of their low power consumption, low cost and compatibility with CMOS technology. CMOS image sensors are now not only used in consumer electronics such as miniature digital cameras (DSC), mobile phone cameras, video cameras, and digital single-lens reflex (DSLR), but also in automotive electronics, monitoring, biotechnology, and medicine. [0003] The pixel unit of the CMOS image sensor is the core device for the image sensor to realize light sensing. The most common pixel cell i...

AI Technical Summary

Problems solved by technology

Due to the use of three layers of metal interconnection layers, the dielectric layer 7 covered above the photodiode 1 is relatively thick, resulting in the loss of incident light

At the same time, for oblique light with a certain incident angle, the thicker dielectric layer 7 may cause the light to fail to reach the surface of the photodiode 1, further reducing the sensitivity

Moreover, the purpose of arranging the power lines 6 using metal three in a grid is to prevent optical crosstalk, but in fact it cannot completely eliminate optical crosstalk

like figure 2 As shown, there is still a large dielectric layer gap between the power line 6 that prevents crosstalk and the control lines 5, 4, and 3 located below it, and the oblique incident light between adjacent pixel units may still be transmitted from one pixel to the other. cell into another pixel cell, will still cause optical crosstalk between pixel cells

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