The chemical structure of trapped charge sites formed at the Si/SiO2 interface by ionizing radiation as determined by XPS

Abstract

Device‐quality gate oxides (∠850 Å) and thin thermal SiO2 (∠80 Å) filmsgrown on Si 〈100〉 substrates are irradiated with 0–20 eV electrons during i n s i t uXPS measurements. The gate‐oxide structures have been thinned to 25–60 Å using a relatively benign wet‐chemical depth‐profiling procedure. Si+3 species at the Si/SiO2interface and oxide/vacuum surface states are generated and allowed to relax during the course of the measurements. This relaxation behavior is examined for sample temperatures from 150 to 523 K. These results are correlated with the presence of a strained layer of SiO2 (∠20 Å) at the interface which we had previously reported. The generation and chemical annihilation of the interfacial Si+3 species is discussed in terms of a structural model. This model provides a framework for the interpretation of hole‐ and electron‐trap generation by ionizing radiation.