Photoemission Spectroscopy Study on Hydrogen Termination Effect on SiO2/Si Structure Fabricated Using H+-Implanted Si Substrate

Abstract

Using proton (H+)-implanted silicon (Si) substrates, we clarified the effect of dangling bond termination by hydrogen on the interfacial strain in the silicon dioxide (SiO2)/Si system. The variations of the SiO2/Si interface structure caused by H+ implantation into a SiO2/Si sample and by hydrogen out-diffusion heat treatment were analyzed by high-resolution synchrotron radiation photoemission spectroscopy. We found that H+ implantation into the SiO2/Si sample [intentional generation of the interfacial dangling bonds] can increase the intensity of the strained-Si peaks in the Si 2p photoemission spectrum. In addition, our study revealed that the strained Si atom amount and dangling bond density are reduced by hydrogen out-diffusion heat treatment. These findings suggest that the increase/decrease in the dangling bond density by H atoms results in the increase/decrease in local strain field around a dangling bond, thereby changing the length of the Si–Si bonds beneath the SiO2/Si interface. Out-diffused hydrogen seems to play roles to not only reduce the dangling bond density but also relax the local strain at the SiO2/Si interface. The hydrogen termination effect is expected to have an advantage in structural stability in the SiO2/Si system as compared with the pure thermal termination effect.