SUPPRESSED CROSS-TALK PIXEL-ARRAY SUBSTRATE AND FABRICATION METHOD

A reduced cross-talk pixel-array substrate includes a semiconductor substrate, a buffer layer, a metal annulus, and an attenuation layer. The semiconductor substrate includes a first photodiode region. A back surface of the semiconductor substrate forms a trench surrounding the first photodiode region in a cross-sectional plane parallel to a first back-surface region of the back surface above the first photodiode region. The buffer layer is on the back surface and has a feature located above the first photodiode region with the feature being one of a recess and an aperture. The metal annulus is on the buffer layer and covers the trench. The attenuation layer is above the first photodiode region.