Proximity Gettering Design of Silicon Wafers Using Hydrocarbon Molecular Ion Implantation Technique for Advanced CMOS Image Sensors

Abstract

The metallic impurity gettering capability of hydrocarbon molecular ion-implanted silicon wafers was demonstrated by using a complementary metal-oxide-semiconductor (CMOS) image sensor that provides floating diffusion amplifier voltage (Vdark) output signals under dark conditions. It was found that the Vdark output signals of hydrocarbon molecular ion implanted p/p- and p/p+ silicon wafers did not increase after intentional contamination with Fe, Cu, Ni and Co metallic impurities. This indicates that the hydrocarbon molecular ion implanted silicon wafers were able to getter metallic impurities in the projection range of hydrocarbon molecular ion implantation during CMOS device fabrication. It was also found that the hydrocarbon-molecular-ion-implanted silicon wafers had improved electrical device performance factors, such as pn-junction leakage current, in actual device process lines. This gettering technique has no dependence on the silicon wafer substrates such as whether it is composed of bulk por p+ boron doped silicon crystals. We believe that the hydrocarbon-molecular-ion-implanted silicon wafers will be advantages for advanced CMOS image sensor fabrication.