[16a-Z26-1~11] 13.5 Semiconductor devices/ Interconnect/ Integration technologies

▲ [16a-Z26-1] Understanding of Subthreshold Swing of Si n-MOSFETs over a Temperature Range from 300 to 38 K

〇(D)Minsoo Kang¹, Kasidit Toprasertpong¹, Mitsuru Takenaka¹, Shinichi Takagi¹ (1.The University of Tokyo)

Keywords:Quantum computer, Cryogenic temperature, Subthreshold swing

Attention has recently been paid to the operation of Si MOSFETs at cryogenic temperature, because of the application of Si CMOS to quantum computing system. Thus, understanding of electrical characteristics of MOSFETs at low temperatures is mandatory. Particularly, the behaviors of subthreshold swing (SS) at low temperatures, which have been reported to have peculiar temperature and I_d dependencies [1-3], are one of the key factors in physical understanding of the properties of cryogenic CMOS. In order to explain SS of Si n-MOSFETs at deep-cryogenic temperatures, which does not follow the Boltzmann thermal limit of, (k_BT/q)ln10, Beckers et al. have proposed models of band tail states [2] and localized states with Gaussian distribution near the band edge [3]. However, the validity of those models has been confirmed in SS in a limited temperature range under a given device condition and, thus, the effectiveness has not been proven over a wide range of temperatures and device parameters. In this study, we evaluate SS of Si n-MOSFETs with a substrates boron concentration of 2×10¹⁷ cm^-3 as a function of I_d at temperatures from 300 to 38 K. We apply the SS model including band tail states and localized states, proposed by Beckers et al. [2, 3], to the SS values taken over a wide range of temperature and I_d and examine the effectiveness.