Simulation Study on a Backside-Illuminated Cascade-Collection-Gate Image Sensor

The current CMOS image sensor exceeded 100 Mfps with 184 consecutive images capturing, while the highest theoretical frame rate of a silicon image sensor with a single shot was proved at 90.1 Gfps. In this paper, we propose a backside-illuminated (BSI) image sensor that can operate at 1 Gfps. The sensor is designed with a silicon dioxide light/charge guide pipe that reduces the spatial crosstalk to a negligible level. At the front side, multiple collection gates, which collect signal electrons, trifurcate to increase the number of in-pixel storage elements. The voltages applied to polysilicon gates use a cascade pipeline scheme with radial direction so that electrons are transferred directly to the storage elements. The sensitivity analyses show that the guide pipe and the driving voltages are correlated and will be optimized for the tradeoff between the temporal resolution and the crosstalk of the image sensor.