Characteristics of SOI structure with buried alumina layer

A SOI (Silicon On Insulator) structure with buried alumina was fabricated by ALD (Atomic Layer Deposition) followed by bonding and etchback process. The interface of alumina and silicon was analyzed by CV measurements and the cross section was investigated by SEM (Scanning Electron Microscope) analysis. The density of interface state of alumina and silicon was 2.5×10 ¹¹ cm ^-2eV ^-1 after high temperature annealing for wafer bonding. It was confirmed that the surface silicon layer was completely isolated from the substrate by cross section SEM and AES (Auger Electron Spectroscope) depth profile. Moreover, XRD (X-ray Diffraction) analysis was carried out to study the crystallization of the alumina layer before and after high temperature annealing. The alumina film is slightly crystallized after annealing. The simulated results confirmed that the lattice temperature of MOSFET on SOI with buried alumina was lower than that of SOI with buried silicon dioxide. A device on this alumina SOI structure would have better thermal properties than one on conventional SOI, due to higher thermal conductivity of alumina than that of silicon dioxide.