Development Of High Resistivity FD-SOI Substrates for mmWave Applications

FD-SOI CMOS technology is entering the mmWave realm, providing undeniable benefits in terms of data-rates, bandwidth, latency and power consumption improvements. The high resistivity substrate option is seen as a major booster to reach ultimate mmWave performances. The engineering challenges related to this new wafer generation are addressed in this paper. We will review benefits and drawbacks of each possible high resistivity material, and discuss process options to enhance performances on resistivity stability and mechanical robustness to deformation through fabrication processes. Specific measurements are presented to show that going from standard to high resistivity substrates did not impact the behaviour of logic devices. Those substrates being destined to RF and mmWave applications, their performance was also measured in terms of small signal response using coplanar waveguides.