Simulation of film structures for CMOS image sensors

摘要

This study will use ANSYS, the commercial finite element analysis software, to simulate the thin film stacked in different processes on CMOS image sensors. For example, the process of color filter stacks will observe the impact with the different stacking structure and electronic properties (leakage current), and using the results to further optimize the structure of thin film stacked or change the film material to achieve the best performance. We use 2D simulation and simplification model to improve simulation efficiency, then modifying material parameters and discussing with stress singularity will get more accurate results. From the study, the film structure will produce residual stress when cooling to room temperature because of materials with the different coefficients of thermal expansion. Comparing of simulation and experiment results will find a trend: When the stress is higher and the leakage is higher; the stress is lower and the leakage is lower. This trend caused by the high stress induced defects, then defects induced high leakage current. The study will use the computer simulation to make the shorter research time, lower experimental costs, and enhancing the defect-free rate of products.