IMAGE SENSOR PIXELS WITH LIGHT GUIDES AND LIGHT SHIELD STRUCTURES

摘要

A front-side illuminated image sensor with an array of image sensor pixels is provided. Each image pixel may include a photodiode, transistor gate structures, shallow trench isolation structures, and other associated pixel circuits formed in a semiconductor substrate. Buried light shielding structures that are opaque to light may be formed over regions of the substrate to prevent the transistor gate structures, shallow trench isolation structures, and the other associated pixel circuits from being exposed to stray light. Buried light shielding structures formed in this way can help reduce optical pixel crosstalk.

主权项

1. An image sensor, comprising:
a substrate; first and second adjacent photodiodes formed in the substrate; a floating diffusion node that is formed between the first and second photodiodes; a buried light shield structure that is formed on top of the substrate over the floating diffusion node, wherein the buried light shield structure has a horizontal segment portion that extends parallel to the surface of the substrate and a vertical segment portion that extends perpendicular to the surface of the substrate; and a shallow trench isolation structure that is formed in the substrate between the first and second photodiodes and that is covered by the buried light shield structure.