Impacts of Thermal Annealing on Hydrogen-Implanted Germanium and Germanium-on-Insulator Substrates

Abstract

Smart-cut and wafer bonding technology has been widely used in the germanium-on-insulator (GOI) fabrication. In this study, the damages formed in hydrogen implanted Ge, the surface blistering, and the GOI post-annealing processes were thoroughly investigated. The blistering of the hydrogen implanted Ge was carried out and compared with various thermal annealing temperatures ranging from 350 to 500°C. For the annealing temperature lower than 500°C, the Ge surface layer was found fully exfoliated with planar crack propagation. But at higher temperatures, discrete blisters were observed because of the very fast diffusion of the implanted hydrogen. Various post-annealing treatments, including annealing in vacuum or in N2 atmosphere were performed on the as-prepared GOI substrates. It was found that post-annealing in vacuum at 500°C improves the crystal quality of the GOI most effectively. As shown by X-ray diffraction (XRD) measurement, the full width at half maximum (FWHM) of the Ge peak was about 72.6 arc sec and almost all the residual stress was released.