  Cryogenic CMOS technology (cryo-CMOS) offers a scalable solution for quantum device interface fabrication. Several previous works have studied the characterization of CMOS technology at cryogenic temperatures for various process nodes. However, CMOS characteristics for various width/length (W/L) ratios and under different bias conditions still require further research. In addition, no previous works have produced an integrated modeling process for cryo-CMOS technology. In this paper, the results of characterization of Semiconductor Manufacturing International Corporation (SMIC) 0.18 {\mu}m CMOS technology at cryogenic temperatures (varying from 300 K to 4.2 K) are presented. Measurements of thin- and thick-oxide NMOS and PMOS devices with different W/L ratios are taken under four distinct bias conditions and at different temperatures. The temperature-dependent parameters are revised and an advanced CMOS model is proposed based on BSIM3v3 at the liquid nitrogen temperature (LNT). The proposed model ensures precision at the LNT and is valid for use in an industrial tape-out process. The proposed method presents a calibration approach for BSIM3v3 that is available at different temperature intervals. 
MOSFET Characterization and Modeling at Cryogenic Temperatures