Hydrogen Termination Effect on SiO₂/Si Interface State Density in CH₃O-Molecular-Ion-Implanted Silicon Epitaxial Wafer for CMOS Image Sensors

Abstract

The reduction in SiO2/Si interface state density (Dit) at the SiO2/Si interface region is important for improving the performance of complementary metal-oxide semiconductor (CMOS) image sensors. The CH3O-ion-implanted region stores hydrogen and releases the stored hydrogen during the subsequent heat treatment. This study demonstrates that a CH3O-ion-implanted epitaxial silicon wafer can reduce the Dit and Pb0 center density in SiO2/Si interface regions, as analyzed by quasi-static capacitance–voltage and electron spin resonance measurements, respectively. Both Dit and Pb0 center density in the CH3O-implanted wafer decreased with increasing heat treatment temperature. Moreover, the activation energy is estimated to be 1.57 eV for the hydrogen termination reactions induced by the CH3O-ion-implanted wafer. The activation energy is close to those of hydrogen molecules and Si dangling bonds at the SiO2/Si interface. The termination effect of the CH3O-molecular-ion-implanted epitaxial silicon wafers can contribute to the high electrical performance of CMOS image sensors.