Study on switch-leakage-induced dark offset of ambient light sensor

摘要

The dark offset which is the reference value of an ambient light sensor is analysed. It varies across the wafer when the temperature is increased because of the leakage current of switch transistors. The difference between before and after wafer revisions shows the clue of leakage current. Modern fabrication processes which change the threshold voltage of switch transistors are surveyed. To explain the discrepancy between test and survey data, some other process issues are discussed.