Abstract
A novel fabrication technique for relaxed and thin SiGe layers on buried oxide (BOX) layers, i.e., SiGe on insulator (SGOI), with a high Ge fraction is proposed and demonstrated for application to strained-Si metal-oxide-semiconductor field effect transistors (MOSFETs). This fabrication technique is based on the high-temperature oxidation of the SGOI layers with a lower Ge fraction. It is found that Ge atoms are rejected from the oxide and condensed in the SGOI layers. The conservation of the total amount of Ge atoms in the SGOI layer is confirmed by structural and compositional analyses of dry-oxidized SGOI layers at 1050°C of different initial thicknesses and oxidation times. Using this technique, a 16-nm-thick SGOI layer with the Ge fraction as high as 0.57 is successfully obtained. The Ge profiles across the SGOI layers are quite uniform and the layers are almost completely relaxed. Significant dislocation generation in the SGOI layer is not observed after the oxidation. This is a promising technique for application to sub-100 nm fully-depleted silicon-on-insulator (SOI) MOSFETs with strained-Si or SiGe channels.