Study Of Pixel Photosensitive Devices On The CMOS Image Sensor

In recent years, with the rapid development of semiconductor industry, the processtechnology, which has stepped from the sub-micro scale into the deep sub-micro scale, hasbeen improved significantly. Meanwhile, the performance of CMOS image sensor has beenhighly increased. CMOS image sensor is a large scale mixed analog-digital integrated circuit,in which A/D converter, digital signal processing, and the time control circuit can beintegrated on one chip. In addition, more advanced performances of CMOS image sensor,such as better imaging capability, low noise, no image lag, and fast readout rate, will certainlybe developed in the future.In the field of practical application, CMOS image sensor is widely used in electronicsproducts, multimedia application, medicine, space exploration,3D, and automotiveapplication, due to the advantages of lower cost, lower power consumption, and easier processtechnology comparing to CCD image sensor. It is pretty clear that the future of CMOS imagesensor is very bright. As a result, it is meaningful to study the performances of CMOS imagesensor.This dissertation reviews the development and applications of CMOS image sensor. Theoperation principle of CMOS image sensor, the theory of the photoelectric conversion, andvarious kinds of performance parameters of CMOS image sensor are also discussed.Furthermore, the design of essential parts of4T CMOS image sensor is presented in detail.The image lag of4T APS is also studied. To study the optimization of pixel in image lagand effectively reduce image lag. At the same time, the capacity of full well capacity and theisolation structure of the pixel region are studied, to explore an optimized structure which cangreatly increase the full well capacity of the pixel photosensitive area. The isolation structureof the pixel region is also analyzed, so as to address a method of air gap shallow trenchisolation structure.