A transmission electron microscope investigation of the dose dependence of the microstructure of silicon‐on‐insulator structures formed by nitrogen implantation of silicon

Transmission electron microscope studies have been made of (100) silicon wafers implanted at 500 °C with 200‐keV 14N+ ions to doses of either 0.25, 0.75, or 1.4×1018 cm−2. For all of these specimens, the as‐implanted wafers contained a buried amorphous layer with a damaged upper single‐crystal silicon layer. For the 1.4×1018 cm−2 specimen, the amorphous layer contained bubbles. Wafers subsequently annealed at 1200 °C in order to form silicon‐on‐insulator structures showed the following. For the 0.25×1018 cm−2 specimen, there was a buried discontinuous polycrystalline α‐Si3N4 layer, and an upper silicon layer with no observable defects. For the 0.75×1018 cm−2 specimen, there was a buried continuous polycrystalline α‐Si3N4 layer containing small silicon islands, and an upper silicon layer either without defects or with microtwins adjacent to the nitride/silicon interface. For the 1.4×1018 cm−2 specimen, there was a buried multilayer structure with the middle layer consisting of substantially single‐crystal ...