28-nm FD-SOI CMOS RF Figures of Merit Down to 4.2 K

Lucas Nyssens,Valeriya Kilchytska,Arka Halder,Jean-Pierre Raskin,Nicolas Planes,Denis Flandre,Babak Kazemi Esfeh

doi:10.1109/jeds.2020.3002201

Abstract

This work presents a detailed RF characterization of 28-nm FD-SOI nMOSFETs at cryogenic temperatures down to 4.2 K. Two main RF Figures of Merit (FoMs), i.e., current-gain cutoff frequency (f t ) and maximum oscillation frequency (f max ), as well as parasitic elements of the small-signal equivalent circuit, are extracted from the measured S-parameters. An improvement of up to ~130 GHz in f t and ~75 GHz in f max is observed for the shortest device (25 nm) at low temperature. The behavior of RF FoMs versus temperature is discussed in terms of small-signal equivalent circuit elements, both intrinsic and extrinsic (parasitics). This study suggests 28-nm FD-SOI nMOSFETs as a good candidate for future cryogenic applications down to 4.2 K and clarifies the origin and limitations of the performance.

Highlights

Numerous studies focused on the cryogenic behavior of advanced CMOS technologies are mainly driven by the perspective of quantum computing applications [1]-[12]
The zero temperature coefficient (ZTC) point at which Id stays invariable with temperature (T) clearly appears at ∼0.83 V
In this work, the prospects of 28-nm fullydepleted silicon-on-insulator (FD-SOI) CMOS for future cryogenic RF applications have been assessed by the analysis of RF FoMs and complete small-signal equivalent circuit elements in the cryogenic temperature range down to 4.2 K

Summary

INTRODUCTION

Numerous studies focused on the cryogenic behavior of advanced CMOS technologies are mainly driven by the perspective of quantum computing applications [1]-[12]. To enable cryo-CMOS, it is essential to embed digital, analog and RF models in a process design kit in order to predict the MOSFETs performances and power dissipation at cryogenic temperatures as required for reliable circuit designs. This motivated several works [6]–[9] and [16]–[19] towards the analysis of advanced MOSFETs behavior at cryogenic temperatures. The present paper extends our previous work [18] It is the continuation of our previous study [17] on the RF performances of 28-nm FD-SOI transistors down to 4.2 K, the liquid-helium temperature. An analysis on the RF FoMs of the FETs is provided

EXPERIMENTAL DETAILS

RESULTS AND DISCUSSION

CONCLUSION