Characterisation of CMOS compatible vertical MOSFETs with new architectures through EKV parameter extraction and RF measurement

Vertical MOSFETs (VMOSFETs) with channel lengths down to 100 nm and reduced overlap parasitic capacitance were fabricated using 0.35 mum lithography, with only one extra mask step compared to standard CMOS technology. EKV modelling produced reasonable fitting of the DC and AC characteristics for short channel devices. It is noted that achieving sufficiently long channels in vertical pillar devices is difficult and introduces challenges for accurate and scalable compact modelling. The measured peak f_T was 7.8 GHz and is significantly limited by high contact resistance and affected by unoptimised junction formation. The study comprehensively reveals structure issues that affect the RF performance. The performance inhibitors have then been optimised using process and device simulation. It is demonstrated that f_T and f_MAX based on the measurement and numerical simulation, can reach 30.5 GHz, and 41 GHz respectively.