Surface Structure of Hydrogen Annealed Silicon Wafer using Ozonized Water and Dilute HF Cleaning

摘要

The mechanism, of which the surface step and terrace structure of a Hydrogen annealed silicon (Si) wafer can be preserved after ozonized (O_3) water and dilute HF (DHF) water cleaning, was investigated using a XPS (X-ray Photoelectron Spectroscope), an AFM (Atomic Force Microscope) and a TEM (Transmission Electron Microscope). The oxide thickness after 30 sec in O_3 water is 0.75nm on both Si(100) and Si(111) surface by XPS. It is well known that SiO_2 films are removed isotropic in DHF water. It is suggested that the surface structure of the hydrogen annealed Si wafer is preserved in oxidation of Si wafer with O_3 water. The surface structure and micro-roughness (Rms) of these wafers are preserved after O_3 water and DHF water treatment by AFM. The Rms of these wafers without O_3 water treatment increases, however, due to the generation of a lot of protrusions on Si(100) surface. The protrusion, consisting of crystalline Si, has the height of 0.6nm and the width of 15nm by TEM. Thus, a formation model for the protrusions is proposed, the generation of depressions with preference native oxide growth at the site of the type-C defects on Si(100) surface and the remain of the protrusions with etching in DHF water.