Near-infrared sensitivity enhancement of a back-illuminated complementary metal oxide semiconductor image sensor with a pyramid surface for diffraction structure

We demonstrated the near-infrared (NIR) sensitivity enhancement of back-illuminated complementary metal oxide semiconductor image sensors (BI-CIS) with a pyramid surface for diffraction (PSD) structures on crystalline silicon and deep trench isolation (DTI). The incident light diffracted on the PSD because of the strong diffraction within the substrate, resulting in a quantum efficiency of more than 30% at 850 nm. By using a special treatment process and DTI structures, without increasing the dark current, the amount of crosstalk to adjacent pixels was decreased, providing resolution equal to that of a flat structure. Testing of the prototype devices revealed that we succeeded in developing unique BI-CIS with high NIR sensitivity.