Proximity gettering technology for advanced CMOS image sensors using carbon cluster ion‐implantation technique: A review

A new technique is described for manufacturing advanced silicon wafers with the highest capability yet reported for gettering transition metallic, oxygen, and hydrogen impurities in CMOS image sensor fabrication processes. Carbon and hydrogen elements are localized in the projection range of the silicon wafer by implantation of ion clusters from a hydrocarbon molecular gas source. Furthermore, these wafers can getter oxygen impurities out‐diffused to device active regions from a Czochralski grown silicon wafer substrate to the carbon cluster ion projection range during heat treatment. Therefore, they can reduce the formation of transition metals and oxygen‐related defects in the device active regions and improve electrical performance characteristics, such as the dark current, white spot defects, pn‐junction leakage current, and image lag characteristics. The new technique enables the formation of high‐gettering‐capability sinks for transition metals, oxygen, and hydrogen impurities under device active regions of CMOS image sensors. The wafers formed by this technique have the potential to significantly improve electrical devices performance characteristics in advanced CMOS image sensors. This paper demonstrates a newly developed gettering wafer production concept using a carbon cluster ion implantation technique for CMOS image sensors, which allows to implant a silicon wafer surface simultaneously with carbon and hydrogen elements that form the projection range, by using a hydrocarbon compound molecular gas source. The authors believe that such wafers will be beneficial for advanced CMOS image sensor fabrication processes.