A 0.9 µm pixel size image sensor realized by introducing organic photoconductive film into the BEOL process

A stacked image sensor with a 0.9 μm pixel size fabricated by using organic photoconductive film (OPF) was realized. It is the first trial to introduce an active material, that is, an organic semiconductor into the BEOL process. This pixel structure is fabricated by using a standard 45 nm BEOL process. However, after OPF deposition, it is essential to restrict the thermal budget and to avoid oxygen, moisture, and plasma irradiation. By controlling the above conditions, a demonstration of a stacked image sensor with OPF, which has high sensitivity, high saturation charge, and a wide incident light angle, was successfully performed.