PIXEL ISOLATION REGIONS FORMED WITH DOPED EPITAXIAL LAYER

摘要

An image sensor may include isolation regions that are formed in between photodiodes. These isolation regions may prevent cross-talk and improve the performance of the image sensor. The isolation regions may be made of epitaxial silicon. The epitaxial silicon may be grown in trenches formed in a substrate using an etching process. Portions of the substrate may be protected from the etching process with a hard mask layer. Photodiodes may later be implanted in these protected portions of the substrate after the isolation regions have been formed. The epitaxial silicon may be boron-doped or antimony-doped epitaxial silicon with a concentration of boron or antimony between 1016 cm3 and 1018 cm3.

主权项

1. A method of forming an image sensor with an array of photodiodes in a substrate and a plurality of isolation regions that isolate each photodiode in the array of photodiodes, comprising:
before implanting the photodiodes in the substrate, forming trenches in the substrate in the isolation regions; before forming the trenches in the substrate, forming a hard mask layer over a portion of the surface of the substrate, wherein forming the trenches in the substrate comprises performing an etching process, wherein the hard mask layer is resistant to the etching process; forming doped epitaxial silicon in the trenches; and removing the hard mask layer from the substrate after forming the doped epitaxial silicon in the trenches.