Pixel structure of CMOS image senor and forming method thereof

Abstract

The invention discloses a pixel structure of a CMOS image senor and a forming method thereof. The pixel structure of the CMOS image senor comprises a semiconductor substrate, a transmission transistor located on the semiconductor substrate, a photodiode located inside the portion, at one side of a gate structure, of the semiconductor substrate and a floated diffusion area located inside the portion, at the other side of the gate structure of the semiconductor substrate,, wherein the transmission transistor comprises the gate structure located on the semiconductor substrate, the photodiode comprises a deep doped area, and the concentration distribution of impurity ions doped in the deep doped area decreased along with the increase of the distance between the deep doped area and the gate structure. According to the pixel structure of the CMOS image senor, photoelectrons can be transmitted to the floated diffusion area easily, and the imaging quality is high.

Description

technical field [0001] The invention relates to the field of image sensors, in particular to a pixel structure of a CMOS image sensor and a forming method thereof. Background technique [0002] Image sensors are divided into complementary metal oxide (CMOS) image sensors and charge-coupled device (CCD) image sensors, which are usually used to convert optical signals into corresponding electrical signals. The advantage of the CCD image sensor is that it has high image sensitivity and low noise, but it is difficult to integrate the CCD image sensor with other devices, and the power consumption of the CCD image sensor is relatively high. In contrast, CMOS image sensors have the advantages of simple process, easy integration with other devices, small size, light weight, low power consumption, and low cost. At present, CMOS image sensors have been widely used in still digital cameras, camera phones, digital video cameras, medical imaging devices (such as gastroscopes), and autom...

AI Technical Summary

Problems solved by technology

Since the potential difference gradually decreases with the transmission of photo-generated carriers, when the potential difference is smaller than the potential barrier between the photodiode PD and the floating diffusion region FD, the photo-generated carriers cannot be transported out and remain in the photodiode PD , superimposed with the photogenerated carriers collected by the photodiode PD next time, forming afterimages and affecting the imaging quality

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