Well to substrate photodiode for use in a CMOS sensor on a salicide process

摘要

An image sensor having a well-to-substrate diode as the photodetector. In a preferred embodiment, a modern salicided (CMOS) process is utilized to manufacture the image sensor. The field oxide region above the diode junction is transparent to visible light, thus allowing the photodiode competitive quantum efficiency as compared to devices having source/drain diffusion-to-substrate photodiodes fabricated on a non-salicided process. The photodiode can be integrated as part of a sensor array with digital circuitry using a relatively unmodified digital CMOS process. Furthermore, the structure allows the optical properties of the photodiode to be engineered by modifying the well without deleterious effects, to approximate a first order, on the characteristics of a FET built in another identical well.