Materials and process controls for scalable and reliable germanium gate stacks

Abstract

Germanium (Ge) is not a new material but now spotlighted for beyond Si-scaled CMOS. Ge p-MOSFETs have been well investigated and its high performance has so far been demonstrated. On the contrary, an achievement of high electron mobility Ge n-MOSFETs is quite challenging due to a large amount of interface states near the conduction band edge. So, we first discuss how to overcome “intrinsic challenges in Ge n-MOSFETs” from thermodynamic viewpoint of GeO2 on Ge. A very low Dit (<1011 eV−1cm−2) at Ge/GeO2 interface and a very high electron mobility in Ge n-MOSFETs are presented. This is further extended to scaled gate stacks on Ge.