Characterization of the Interface between the Top Si and Buried Oxide in Separation by Implanted Oxygen Wafers

Abstract
The electrical characteristics of the top Si-buried oxide interface in low-dose separation by implanted oxygen (SIMOX) wafers have been investigated from high-frequency and quasi-static capacitance–voltage (CV) measurements of the buried metal oxide semiconductor (MOS) diodes proposed here. The structure of the interface has been also analyzed using cross-sectional transmission electron microscopy (XTEM). SIMOX wafers with an internal thermal oxidation (ITOX) process have a fixed charge density of 2.7×1010 cm-2 and an interface trap density of 5×109 cm-2 eV-1. XTEM analysis revealed the undulation of the interface with ITOX is about 1 lattice. From the small fixed charge density and the smooth interface, we conclude that the strain field in the top Si-buried oxide interface is small, and comparable to that of thermal oxide-Si interface. The obtained results indicate that ITOX-SIMOX wafers are useful for the fabrication of fully depleted MOSFETs.