Image sensor and method for forming the same

Abstract

The invention relates to an image sensor which consists of a device isolating layer positioned between photoelectric diode areas of two adjacent pixel unit areas, a first doping trap positioned in thephotoelectric diode area under a semiconductor underlayer surface and provided with a first conducting type, a second doping trap provided with a second conducting type and positioned under the firstdoping trap and an isolating trap which is also formed under the device isolating layer of the semiconductor underlayer; the bottom of the isolating trap is positioned under the second doping trap. The image sensor has the advantages that the production of drain current in the photoelectric diode area of adjacent pixel units can be effectively prevented by adopting the isolating trap to isolate the photoelectric diode area between the pixel units; meanwhile, as the isolating trap is positioned under the device isolating layer while the bottom of the isolating trap is positioned under the first doping trap of the photoelectric diode, the surface of the photoelectric diode area is not reduced and the performance of the photoelectric diode is guaranteed .

Description

technical field [0001] The invention relates to the field of semiconductor technology, in particular to an image sensor and a forming method thereof. Background technique [0002] At present, the charge coupled device (CCD) is the main practical solid-state image sensor device, which has the advantages of low read noise, large dynamic range, and high response sensitivity. However, CCD also has the disadvantage of being difficult to be compatible with the mainstream Complementary-Metal-Oxide-Semiconductor (CMOS) technology, that is, the CCD-based image sensor is difficult to achieve single-chip integration. The CMOS image sensor (CMOS Image sensor, CIS) adopts the same CMOS technology, and can integrate the pixel cell array and peripheral circuits on the same chip. Compared with CCD, CIS has the advantages of small size, light weight, low power consumption, The advantages of convenient programming, easy control and low average cost. [0003] Generally, a CMOS image sensor i...

AI Technical Summary

Problems solved by technology

However, with the above technology, since the deep trenches and device isolation layers exist in parallel between adjacent photodiode regions, the effective area of ​​the photodiode is reduced, so the response speed and quality of the pixel unit to light will be reduced, which will affect the performance of the pixel unit.

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