Pixel Technology for Improving IR Quantum Efficiency of Backside-illuminated CMOS Image Sensor

Abstract

In this paper, we present CMOS image sensor containing suitable pixel structure for IR light harvesting. In order to enhance the IR sensitivity, several pixel process technologies have been applied such as silicon thickness increment, anti-reflecting layer (ARL) modification, and introduction of backside scattering technology (BST). The effect of each technology on the infra-red quantum efficiency (IRQE) of image sensor has been demonstrated. The BST patterns were formed at silicon surface for the light scattering effect. In order to investigate the effect of light scattering, the quantum efficiencies and the optical crosstalk between the neighboring pixels based on various BST shapes were measured. By using the above technologies, IRQE of the image sensor has dramatically increased up to 43% at 940nm wavelength, which is nearly 400% enhancement compared to the conventional image sensor.