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

Abstract

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.

Formation of Cone-Shaped Inclusions and Line Defects on the Cz-Si Wafer Surface by the Helium Implantation and DC Nitrogen Plasma Treatment

“…The topicality of investigations presented in this work is determined by the fact that the practical appropriateness of silicon-on-insulator wafers formed by the method proposed in [1] requires the conservation of perfectness of silicon wafer surface and its near-surface (working) area. On the other hand, the plasma influence can modify the surface properties due to both introduction of impurity atoms (nitrogen, in our case) and formation of defects by ion beam.…”

“…In work [1] we investigated the possibility of forming buried insulating Si x N y layers by a new method based on the nitrogen gettering onto the buried defect layer created by helium implantation.…”