Investigation of silicon on insulator fabricated by two-step O＋ implantation

In this paper, we investigated the dose window of forming a continuous buried oxide （BOX） layer by single implantation at the implantation energy of 200 keV. Then, an improved two-step implantation process with second implantation dose of 3×10^15 cm-2 was developed to fabricate high quality separation by implanted oxygen （SIMOX） silicon on insulator （SOI） wafers. Compared with traditional single implantation, the implantation dose is reduced by 18.2%. In addition, the thickness and uniformity of the BOX layers were evaluated by spectroscopic ellipsometry. Defect-free top Si as well as atomic-scale sharp top Si/buried oxide interfaces were observed by transmission electron microscopy, indicating a high crystal quality and a perfect structure of the SOI fabricated by two step implantation. The top Si/BOX interface morphology of the SOI wafers fabricated by single or two-step implantation was also investigated by atomic force microscopy.