Ultra-thin SOI wafer technologies for 22/20nm CMOS or beyond

Ultra-thin SOI wafer technologies designed for 22/20nm CMOS are presented. It is stressed that planar, non-doped, and fully-depleted (FD) SOI structures are realistic options that not only solve various scaling issues, but also provide simplicity and flexibility in the device process and the circuit design. To realize 22/20nm planar FD-SOI CMOS, 300mm SOI wafer process by Smart Cut™ [1] has been optimized, focusing on the uniformity of Si film thickness, and adjusting thickness of buried oxide (BOX). It is shown that thickness variation of a 12nm-thick Si film can be controlled within +/- 2.5% for the whole wafer area. Also, buried-oxide (BOX) can be reduced down to 10nm while maintaining high bonding quality, which is expected to provide 22/20nm FD-SOI CMOS with additional advantages, such as improved short channel effect, multi-threshold voltages, and SOI-bulk hybrid structure. It is also shown that these technologies are extending planar CMOS roadmap beyond 22/20nm nodes.