US Patent 9659981 Backside illuminated image sensor with negatively charged layer

A semiconductor image sensor device having a negatively-charged layer includes a semiconductor substrate having a p-type region, a plurality of radiation-sensing regions in the p-type region proximate a front side of the semiconductor substrate, and a negatively-charged layer adjoining the p-type region proximate the plurality of radiation-sensing regions. The negatively-charged layer may be an oxygen-rich silicon oxide, a high-k metal oxide, or a silicon nitride formed as a liner in a shallow trench isolation feature, a sidewall spacer or an offset spacer of a transistor gate, a salicide-block layer, a buffer layer under a salicide-block layer, a backside surface layer, or a combination of these.