Buried Insulating Layer Formation in Cz Si Wafers after Helium Implantation, Nitrogen Plasma Treatment and Annealing

Standard p-type 12 cm Cz Si wafers were implanted by helium ions. The implanted and nonimplanted samples were subsequently subjected to nitrogen plasma treatment and final vacuum annealing. SEM studies have shown the absence of large-scale defects on the top wafer surface and the presence of a layer revealing contrast with surrounding silicon on the cleavage surface at a depth corresponding to the projected range Rp. Scanning over a crater formed by ion sputtering has exposed no defects to the depth of Rp and beyond. At the same time, at a depth of Rp there is a layer with the morphology (structure) significantly different from the surrounding defect-free areas. The measurements of transverse conductivity have shown that the wafer with the formed nitrogen-contained layer possesses dielectric properties with a breakdown voltage up to 15 V.