Reduced cross-talk pixel-array substrate and fabrication method
AssigneeOmniVision Technologies, Inc.
InventorSeong Yeol Mun
Life of this patent
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Abstract
A pixel-array substrate includes a semiconductor substrate, a buffer layer, and a metal annulus. 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 (i) a thin buffer-layer region located above the first-photodiode region and (ii) a thick buffer-layer region forming an annulus above the trench in a plane parallel to the cross-sectional plane. The metal annulus is on the buffer layer and covers the thick buffer-layer region.
Claims20
A reduced cross-talk pixel-array substrate comprising:
- a semiconductor substrate including a first-photodiode region, a back surface of the semiconductor substrate forming 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;
- a buffer layer on the back surface and having (i) a thin buffer-layer region located above the first-photodiode region and (ii) a thick buffer-layer region that (a) is thicker than the thin buffer-layer region, and (b) forms an annulus above the trench in a plane parallel to the cross-sectional plane;
- and
- a metal annulus on the buffer layer and covering the thick buffer-layer region.
A method for fabricating a pixel-array substrate comprising:
- forming a metal annulus on a buffer layer disposed on a semiconductor substrate;
- decreasing a thickness of buffer-layer regions of the buffer layer not located beneath the metal annulus to yield a thinned buffer layer;
- and
- depositing a conformal metal layer on the thinned buffer layer and the metal annulus.
Dependencies are inferred from the claim text.