Ultrahigh vacuum system for atomic-scale planarization of 6 inch Si(001) substrate

Ultrahigh vacuum (UHV) system equipped with aluminum radiation shields has been developed in order to obtain atomically flat Si(001) surfaces in a large area. Aluminum radiation shields were employed to suppress the temperature rise of chamber walls. The UHV system has enabled a 6 inch substrate to be heated up to 700°C under a pressure of less than 10−8 Pa range. The surface structure of the substrate was confirmed by the reflection high energy electron diffraction (RHEED), when the 6 inch substrate was heated at 600°C in UHV after a modified RCA cleaning, the RHEED pattern indicated oxide free surface consisted of2 × 1structure. The roughness was evaluated from numerous observations by cross-sectional transmission electron microscopy (XTEM). Root-mean-square roughness of the Si surface was less than 0.1 nm for almost all over the 6 inch substrate. This implies that the heating in this system gives rise to the atomic-scale planarization of the 6 inch substrate.