Proximity gettering technique using CH3O multielement molecular ion implantation for the reduction of the white spot defect density in CMOS image sensor

Abstract

We have characterized CH3O ion-implanted epitaxial wafers in device fabrication processes. We confirmed that the CH3O ion-implanted wafers can reduce the density of white spot defects in CMOS image sensors. Evaluation of the CH3O ion-implanted region before and after device fabrication processes which included heat treatment and ion implantation, showed that two types of defects, namely stacking faults and carbon-related defects, exist in the CH3O ion implantation region getter the metallic impurities during device fabrication processes. In particular, it was clarified that stacking fault defects existing in the CH3O ion-implanted region are powerful gettering sinks for oxygen. Thus, it was considered that two types of gettering sink formed by CH3O ion implantation contribute to the reduction in the density of white spot defects. We believe that these characteristics can contribute to the improvement of fabrication processes for advanced CMOS image sensors.