Study for cross contamination between CMOS image sensor and IC product

In the authors' fab, CIS (CMOS image sensor) and IC products are in mass production. However, CIS products have an extra color filter (CF) process after traditional IC processing, and color filter (CF) processes are composed of multi-color photoresist layers. The color photoresist contains many metal impurities. Based on experimental data, these metal impurities influence the gate oxide quality of IC devices to induce electrical characteristics variation. If the IC production line is contaminated by metal impurities from CF photoresists, it can be a severe reliability problem. In order to avoid cross contamination, the mixed production of IC and CF process is absolutely forbidden. This study demonstrates cross contamination effects on IC devices and how to prevent cross contamination.