Singnificantly Improved Front Side Illuminated Photodiodes - Integrated in a 0.18 µm Modular CMOS Foundry Technology

Abstract
Broadband reduced reflection loss of front side illuminated photodiodes realized within the restrictive environment of a standard 0.18 μm CMOS production process without compromising dark current, capacitance or any other parameter.

The Challenges of a CMOS Backend
Advanced CMOS technologies realize complex electrical routing in their backend. Optical sensors implemented therein face the difficulty that light needs to pass through this backend stack. With copper metallization, the need for special light pipes came up, and nowadays avoiding the light passing through the frontend by using back side illumination (BSI) is common. BSI is additional effort and products which do not afford it, would benefit from a better light coupling.