Comparison of Photosensing Structures in CMOS Standard Technology for Time-of-Flight Sensors

This paper presents a study of the different photosensing structures available in conventional standard CMOS processes to be used for the implementation of the so-called Time-of-Flight (ToF) sensors, capable of capturing three-dimensional information of a scence. As commercial ToF sensors must meet the requirements of low cost, high speed and noise inmunity, we have analyzed the different photosensing structures in terms of their quantum efficiency, dark current and transient response. Simmulations were performed using ATLAS, showing the strengths and drawbacks of each structure. This analysis permits to make an a priori estimation of the minimum sensable incident power for each device based on its dimensions and the target CMOS technology node.

keywords: Time-of-Flight, CMOS Photosensors