極薄い保護酸化膜を有した高濃度リンドープシリコンの昇温清浄化過程

Abstract

Heavily phosphorus-doped silicon wafers were prepared by the Shiraki method as a chemical treatment. The thermally stimulated desorption (TSD) from these samples with thin oxide films was studied by using Auger electron spectroscopy (AES), electron energy loss spectroscopy (EELS), and mass spectroscopy. The chemical states of the etched surfaces were measured by X-ray photoelectron spectroscopy (XPS). It was found that the thin oxide film on the doped polycrystalline Si surface was desorbed easily at relatively low temperature (560°C), similarly to a single-crystal one. The desorption of the oxide is due to the chemical state from the interface to the near-surface region which includes not only SiO2 but also SiOx. For a single-crystal silicon, a large quantity of phosphorus segregated to the near-surface region even after the oxide had desorbed. It is considered that this phosphorus segregation is attributable to the existence of the strain which is not relaxed because of the low annealing temperature even after desorption of the oxide.