Radiation effects and reliability characteristics of Ge pMOSFETs

Germanium (Ge) is a promising channel material to replace silicon (Si) for the sub-10 nm CMOS technology node. However, the realization of Ge-based MOSFET may be limited by its poor reliability characteristics. In addition, radiation exposure on MOSFET might be regarded as one of reliability issues in terms of lifetime and stability, because the high-energy extremely ultraviolet has become the most promising light source for next generation lithography. Hence, radiation exposure and FN stress on Ge MOSFET are investigated in this work. It is found that the threshold voltage shift and transconductance degradation induced by radiation damage in Ge MOSFETs are minor, while the changes of subthreshold swing and on/off current ratio are severe. On the other hand, the characteristic degradation induced by FN stress is totally different from that by radiation exposure.