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We have developed silicon epitaxial wafers with high gettering capability using hydrocarbon molecular ion implantation for advanced Complementary Metal-Oxide-Semiconductor (CMOS) image sensors. These wafers have three unique silicon wafer characteristics for improvement of CMOS device electrical parameter such as high metallic impurity gettering, oxygen out-diffusion barrier effects from Czochralski silicon (CZ) substrate and hydrogen passivation effect for interface state defect at Si/SiO2. We demonstrate that double epitaxial growth silicon wafers have an extremely high gettering capability during CMOS device fabrication process. We also found that gettering capability strongly dependence on oxygen impurity amount in hydrocarbon molecular ion implantation projection range. We believe that this novel silicon wafer can drastically contribute to the improvement of CMOS image sensor device performance such as white spot defect and dark current.

Gettering sinks for metallic impurities formed by carbon-cluster ion implantation in epitaxial silicon wafers have been investigated using technology computer-aided design and atom probe tomography (APT). We found that the defects formed by carbon-cluster ion implantation consist of carbon and interstitial silicon clusters (carbon-interstitial clusters). Vacancy-type clusters are not dominant gettering sinks for metallic impurities in the carbon-cluster ion implanted region. APT data indicated that the distribution of oxygen atoms in the defects differs between Czochralski-grown silicon and epitaxial silicon wafers. The high gettering efficiency observed in carbon-cluster ion implanted epitaxial silicon wafers in comparison with Czochralski-grown silicon wafers is due to the distribution of oxygen atoms in the defects. Defects not containing O atoms provide strong gettering sinks for metallic impurities. These defects are formed by only carbon-interstitial clusters. Oxygen atoms inside the defects modify the amount of carbon-interstitial cluster formation on the defects. It is suggested that the gettering efficiency for metallic impurities in carbon-cluster ion implanted epitaxial silicon wafer is determined by the amount of carbon-interstitial clusters.

We developed silicon epitaxial wafers with high gettering capability by using hydrocarbon−molecular−ion implantation. These wafers also have the effect of hydrogen passivation on process-induced defects and a barrier to out-diffusion of oxygen of the Czochralski silicon (CZ) substrate bulk during Complementary metal-oxide-semiconductor (CMOS) device fabrication processes. We evaluated the electrical device performance of CMOS image sensor fabricated on this type of wafer by using dark current spectroscopy. We found fewer white spot defects compared with those of intrinsic gettering (IG) silicon wafers. We believe that these hydrocarbon−molecular−ion−implanted silicon epitaxial wafers will improve the device performance of CMOS image sensors.