First Demonstration of Hybrid CMOS Imagers With Simultaneous Very Low Crosstalk and High-Broadband Quantum Efficiency

摘要

One key challenge in the development of backside-illuminated CMOS imagers is to keep crosstalk $(XT)$ low while enabling high quantum efficiency $(QE)$. In this paper, the tradeoff between $XT$ and $QE$ is optimized and demonstrated in two ways. First, a novel optimized two-step graded EPI was developed and implemented, giving excellent $QE$ and $XT$ data. Second, in other imagers, pixel-separating trenches were employed to eliminate $XT$, although at the cost of reduced $QE times fill factor$. Finally, to accurately evaluate the $XT$ performance, an innovative on-chip slanted light shield was implemented on the imager array periphery, eliminating the need for a complex $XT$ characterization setup.