Empirical Approach to Improve the BSIM4 Model for Bulk MOSFETs Scaled Down to Cryogenic Temperature

This paper presents an empirical approach for modeling low-voltage N-MOSFET scaled down to cryogenic temperature. Accurate modeling of MOSFET behavior at cryogenic temperatures down to 4 K remains a challenge for standard compact models, such as BSIM4, due to limited parameter scaling capabilities across the temperature range. We propose a methodology integrating polynomial fitting of temperature-sensitive parameters into the BSIM4 framework, enabling more accurate predictions across temperatures from 300 K down to 4 K. The key advantage of our approach is its ability to maintain scalability and accuracy across both cryogenic and room temperature conditions by tuning very few model parameters. This is validated using measured MOSFET data, showing significant improvements in intermediate temperature modeling (e.g., 77 K, 150 K) compared to conventional approaches. This work offers a practical solution for cryogenic compact modeling and provides a foundation for further advancements in cryogenic CMOS circuits for emerging applications such as quantum computing, space electronics, ultra-low power systems, etc.