Duane Morris, LLP
Effective method to improve sub-micron color filter sensitivity
An image sensor device and method for forming said device are described. The image sensor structure comprises a substrate with photodiodes, an interconnect structure formed on the substrate, a color filter layer above the interconnect structure, a first microlens array, an overcoat layer, and a second microlens array. A key feature is that a second microlens has a larger radius of curvature than a first microlens. Additionally, each first microlens and second microlens is a flat convex lens. Thus, a thicker second microlens with a short focal length is aligned above a thinner first microlens having a long focal length. A light column that includes a first microlens, a second microlens and a color filter region is formed above each photodiode. A second embodiment involves replacing a second microlens in each light column with a plurality of smaller second microlenses that focus light onto a first microlens.
Taiwan Semiconductor Manufacturing Company
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Hung-Jen Yi-Ming Fu-Tien Yu-Kung Chin-Kung Chin-Chen
Hsu Dai Weng Hsiao Chang Kuo