Strained Silicon Fin-Based High Electron Mobility Transistor for Optimal Device Design of Performance and Reliability

Abstract

I present the predictions of scaling and process variation for a strained-silicon (s-Si) fin-based high electron mobility transistor (FinHEMT) with well-tempered, short-channel characteristics. The operation principle of FinHEMT, which the SiGe behaves as an additional insulator forming quantum well (QW) channel in s-Si with the conduction band off-set improving the effective electron mobility, is clearly shown. By calibrating with experimental data, the high electron mobility ( ~1100 cm2/Vs) and enhanced effective mobility (up to 2×) of the FinHEMT is predicted by suppressing the surface roughness scattering effect in the s-Si QW channel. An extensive simulation is performed to find the optimized structure. The Si capping layer is replaced as high- dielectric insulator to prevent the gate leakage current, and undoped SiGe layer is eliminated because the conduction band off-set (EC) is enough to confine the electrons in s-Si QW channel. The parameter analysis is performed for both long and short channel regime of FinHEMT. Finally, suppressed OFF-current (IOFF) and improved ON-current (ION) with enhanced mobility can be achieved by fabrication process optimization and 1019 cm-3 of doping concentration and 2 nm thick of SiGe. Especially in short channel regime, maximized ION and gate controllability clarify the FinHEMT optimization. With enhanced effective mobility, excellent scalability of the FinHEMT ION > 1.1 mA/m at LG= 10 nm is predicted because the high channel mobility can reduce the series resistivity in the scaled device. Owing to this low series resistivity, The FinHEMT has little effect on the process variation. Moreover, the unique operation principle of FinHEMT, which the part of doped SiGe layer behaves as an additional high- dielectric insulator, enhances the hot carrier reliability of FinHEMT by suppressing gate leakage current.