Structure of anti-light-leakage global pixel unit and formation method

Abstract

The invention discloses a structure of an anti-light-leakage global pixel unit. The surface of a grid electrode of a transmission tube, the surface of a grid electrode of a reset tube and the surfaceof a storage node are covered with a metal mask layer, and the metal mask layer forms an opening of the metal mask layer above the storage node; a first contact hole which penetrates through the opening of the metal mask layer is connected to the upward side of the storage node; a second contact hole is formed in the metal mask layer of the transmission tube grid electrode in an isolated mode; a third contact hole is formed in the metal mask layer of the grid electrode of the reset tube in an isolated mode; the upper ends of the first contact hole to the third contact hole are connected to a back first metal interconnection layer to form a composite light blocking structure with the back first metal interconnection layer; and the light leakage gap between the first contact hole and the metal mask layer opening is shielded, so that accuracy of signals in a storage capacitor can be guaranteed, and distortion of output signals is avoided. The invention further discloses a formation methodof the structure of the anti-light-leakage global pixel unit.

Description

technical field [0001] The present invention relates to the technical field of CMOS image sensors, and more particularly, to a structure and a method for forming a global pixel unit of a CMOS image sensor capable of preventing light leakage. Background technique [0002] An image sensor refers to a device that converts optical signals into electrical signals. Generally, large-scale commercial image sensor chips include charge-coupled device (CCD) and complementary metal-oxide semiconductor (CMOS) image sensor chips. [0003] Compared with traditional CCD sensors, CMOS image sensors have the characteristics of low power consumption, low cost, and compatibility with CMOS technology, so they are more and more widely used. Now CMOS image sensors have not only been used in the field of consumer electronics, such as miniature digital cameras (DSC), mobile phone cameras, video cameras and digital single-lens reflex cameras (DSLR), but also in automotive electronics, monitoring, bio...

AI Technical Summary

Problems solved by technology

There is no metal masking layer 17 or contact hole 15 covering the light leakage gap 18, so the incident light can directly pass through the light leakage gap 18 to reach the storage node 12, resulting in parasitic light response, resulting in distortion of the global pixel storage signal and degradation of image quality

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