Low Temperature Effect on Strained and Relaxed Ge pFinFETs STI Last Processes

Abstract

Ge pFinFETs, fabricated either with an STI last process on a Ge-on-Si virtual substrates or a SiGe strain-relaxed buffer, have been systematically evaluated at temperatures from 200 K down to 77 K. In the first cases, the Ge channel is relaxed, while in the second case, compressively strained fins have been obtained. Cryogenic testing shows to be an important tool for evaluating the static device performance parameters and it helps to resolve the impact of strain on the drain current. Apart from that, the off-state leakage in the subthreshold region can be evaluated as a function of temperature, showing that besides thermal Shockley-Read-Hall generation, other field-assisted mechanisms play a role.