Hydrogen diffusion behavior in CH2P-molecular-ion-implanted silicon wafers for CMOS image sensors

Three-dimensional (3D) stacked complementary metal oxide semiconductor (CMOS) image sensors require reduction in leakage current due to interface state defects at the SiO2/Si interface. Hydrocarbon molecular ion implanted silicon wafers have identified the hydrogen termination effect of such wafer, contributing to high performance of CMOS image sensors. However, recently, low-temperature heat treatment during a device pro-cess has been shown to reduce the concentration of hydrogen diffusing from the hydrocarbon-molecular-ion-implanted region. Thus, a new method of molecular ion implantation with phosphorus added has been devel-oped. In this paper, we present the results of our analysis of the diffusion behavior of hydrogen in a hydrocarbon molecule with phosphorus (CH2P) by reaction kinetic analysis and TCAD simulation. The results of reaction kinetic analysis show binding energies of 0.76 eV (C-H-2 binding state) and 0.45 eV (P-H binding state). TCAD simulation results show that the 0.76 eV binding energy indicates that hydrogen is adsorbed in a carbon and silicon self-interstitial cluster (C/I cluster). On the other hand, the binding energy of 0.45 eV indicates that hydrogen is trapped in phosphorus complexes. Hydrogen in the CH2P-implanted region diffuses owing to the difference in between these binding states. Thus, a reduction in the interface state density of Si/SiO2 can be expected.