A kind of cmos image sensor and its manufacturing method

Abstract

The invention discloses a method for manufacturing a CMOS (complementary metal oxide semiconductor) image sensor. The method includes forming MOS (metal oxide semiconductor) transistor regions and a photodiode region on a substrate; forming a metal interconnection structure on the MOS transistor regions in an interconnection dielectric layer; depositing and etching a micro-lens dielectric layer to form an embedded micro-lens positioned on the photodiode region; forming top metal interconnection lines on the metal interconnection structure; depositing and etching a top interconnection dielectric layer so as to form a groove above the embedded micro-lens; and forming first reflecting layers and second reflecting layers on first portions and second portions. The upper surface of each top metal interconnection line is narrow, the lower surface of each top metal interconnection line is wide, and in other words, the cross section of each top metal interconnection line is trapezoidal. The groove comprises the first portions and the second portions, the first portions are positioned above the top metal interconnection lines, and the top metal interconnection lines circle to form the second portions. The invention further discloses the CMOS image sensor. The CMOS image sensor and the method have the advantages that a large quantity of incident light can reach a photosensitive region of a photodiode to participate in a photoelectric conversion procedure, and the sensitivity of pixel units is effectively improved.

Description

technical field [0001] The invention relates to the field of image sensors, in particular to a CMOS image sensor. Background technique [0002] Generally, an image sensor refers to a device that converts an optical signal into an electrical signal. Image sensors 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 are not only 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 widely used in automotive electronics, monitoring, biotechnology and medicine. . [0004] CMOS image sensors can be classified into three-tube, four-tube and five-tube types according to the number ...

AI Technical Summary

Problems solved by technology

Since there are 3, 4 or 5 MOS transistors used for signal control between the photodiode regions 20, which occupy a large area, and in order to prevent the incident light from reaching the surface of the MOS transistors to generate noise and crosstalk, the metal interconnection line 1a, 2a, 3a completely cover the MOS transistor region 10, so that the vertical incident light and oblique incident light of the MOS transistor region 10 covered by the metal interconnection line are all reflected, so that the filling factor of the pixel unit in the CMOS image sensor is between 20% and 50 %, which means that the incident light on 50% to 80% of the area is shielded and cannot participate in the process of photoelectric conversion, thus resulting in the loss of incident light and the reduction of the sensitivity of the pixel unit

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