Recent Progress of Germanium Gate Stack Technology

Ge technology is obviously not new, but its recent progress is in marked contrast to the past research and is based on deep understanding of materials science in Ge (1). Ge CMOS is quite interesting not only from the high mobility but also from CMOS compactness rather than "III-V for n-MOS and Ge for p-MOS". From the EOT scalability viewpoint, sub-nm EOT gate stacks are required to keep the intrinsically high performance of Ge. GeO_x-free gate stacks will be another advantage of Ge by choosing appropriate high-k dielectrics. Furthermore, we can expect versatile device opportunities and applications more suitable for Ge such as pure metal source/drain FETs or junction-less FETs.