Denuded zone formation in carbon-implanted silicon and its application to device quality silicon-on-insulator preparation

For producing ultrathin (<0.1 μm) device quality silicon-on-insulator (SOI) films, commercially available 4-in. diameter (100) SOI wafers with single-crystal layer thickness of 1.5±0.5 μm were carbon-implanted (190 keV and 3×1016 cm−2) followed by bonding to oxidized Si wafers. The buried oxide in the SOI wafers was used as the first etch stop and the second etch was stopped at the implanted carbon peak. The formation of a carbon denuded zone allowed us to obtain ≤900±50 Å SOI films free of carbon precipitation. Since precision polishing to thin one wafer of a bonded pair down to ±0.5 μm in thickness variation is available in industry, it should be possible to start the described SOI process with a bulk Si wafer, rather than an expensive SOI wafer, and obtain similar results.