Enhancement of wafer test/package yields by oxide-capping of microlens in CMOS image sensor

This paper reports the oxide-capping process of microlenses in a CMOS image sensor and its effect on wafer test/package yields of the product. CMOS image sensors with 8 /spl mu/m/spl times/8 /spl mu/m pixel size were fabricated by 0.5 /spl mu/m CMOS logic process incorporated with color filter and microlens processes. After the formation of the microlens, a thin oxide film was deposited as a capping material, and finally pad windows were opened. From the analysis of the yield data, it is concluded that the oxide-capping of the microlenses guarantees the stable wafer test yield and also gives rise to noticeable increase of package yield for CMOS image sensors.