Backside illuminated sensor pixel structure

Abstract

Backside illuminated sensor pixel structure. In one embodiment, an image sensor includes a plurality of photodiodes arranged in rows and columns of a pixel array that are disposed in a semiconductor substrate. Individual photodiodes of the pixel array are configured to receive incoming light through a backside of the semiconductor substrate. The individual photodiodes have a diffusion region formed in an epitaxial region and a plurality of storage nodes (SGs) that are disposed on the front side of the semiconductor substrate and formed in the epitaxial region. An opaque isolation layer havinga plurality of opaque isolation elements is disposed proximate to the front side of the semiconductor substrate and proximate to the diffusion region of the plurality of photodiodes. The opaque isolation elements are configured to block a path of incoming light from the backside of the semiconductor substrate toward the storage nodes.

Description

technical field [0001] The present disclosure relates generally to the design of image sensors, and in particular to image sensors that reduce optical crosstalk. Background technique [0002] Image sensors have become ubiquitous. It is widely used in digital still cameras, cellular phones, security cameras, as well as in medical, automotive and other applications. The technology used to make image sensors continues to make strides. For example, the need for higher image sensor resolution and lower power consumption motivates further miniaturization and integration of image sensors into digital devices. [0003] As the resolution of image sensors increases, the pitch between photodiodes typically decreases, resulting in narrower and deeper photodiodes. These more closely packed photodiodes are more susceptible to optical noise caused by stray light. For example, after illuminating a target photodiode, incoming light may be reflected towards neighboring photodiodes, thus i...

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Problems solved by technology

Therefore, the accuracy or range of applicability of the image sensor may be limited

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