Ge diffusivity from a buried SiO2 layer of a silicon-on-insulator (SOI) structure has been studied as a function of annealing temperature. It has been shown that, at an annealing temperature lower than 900°C, almost all Ge is localized in the implantation region of the SiO2 layer. As the annealing temperature is raised to 1100°C, migration of ion-implanted Ge is accompanied by several processes: diffusion into SiO2, accumulation at Si/SiO2 interfaces, diffusion into silicon, and evaporation from silicon. At 1100°C, Ge diffuses from SiO2 to the bonding interface of the SOI structure with the diffusion coefficient of ~2 × 10−15 cm2/s, which is 2 orders of magnitude higher than its equilibrium value. Depending on the thickness of the silicon layer, formation of a Ge or SiGe phase is detected after annealing at a temperature of 1100°C.
- ion implantation
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