High-Performance P- and N-Type SiGe/Si Strained Super-Lattice FinFET and CMOS Inverter: Comparison of Si and SiGe FinFET

Abstract

This research presents the optimization and proposal of P- and N-type 3-stacked Si0.8Ge0.2/Si strained super-lattice FinFETs (SL FinFET) using Low-Pressure Chemical Vapor Deposition (LPCVD) epitaxy. Three device structures, Si FinFET, Si0.8Ge0.2 FinFET, and Si0.8Ge0.2/Si SL FinFET, were comprehensively compared with HfO2 = 4 nm/TiN = 80 nm. The strained effect was analyzed using Raman spectrum and X-ray diffraction reciprocal space mapping (RSM). The results show that Si0.8Ge0.2/Si SL FinFET exhibited the lowest average subthreshold slope (SSavg) of 88 mV/dec, the highest maximum transconductance (Gm, max) of 375.2 μS/μm, and the highest ON–OFF current ratio (ION/IOFF), approximately 106 at VOV = 0.5 V due to the strained effect. Furthermore, with the super-lattice FinFETs as complementary metal–oxide–semiconductor (CMOS) inverters, a maximum gain of 91 v/v was achieved by varying the supply voltage from 0.6 V to 1.2 V. The simulation of a Si0.8Ge0.2/Si super-lattice FinFET with the state of the art was also investigated. The proposed Si0.8Ge0.2/Si strained SL FinFET is fully compatible with the CMOS technology platform, showing promising flexibility for extending CMOS scaling.

Keywords

• super-lattice
• strain
• SiGe
• FinFET
• inverter
• ON–OFF current ratio