Impact of gate metal work-function engineering for enhancement of subthreshold analog/RF performance of underlap dual material gate DG-FET

Abstract

This work presents a systematic comparative study of analog/RF performance for underlap dual material gate (U-DMG) DG NMOSFET. In previous works, improved device performances have been achieved by use of high dielectric constant (k) spacer material. Although high-k spacers improve device performance, the intrinsic gain of the device reduces. For the analog circuits applications intrinsic gain is an important parameter. Hence, an optimized spacer material having dielectric constant, k=7.5 has been used in this study and the gain is improved further by dual-material gate (DMG) technology. In this paper we have also studied the effect of gate material having different work function on the U-DMG DG NMOSFETs. This device exploits a step function type channel potential created by DMG for performance improvement. Different parameters such as the transconductance (gm), the gain per unit current (gm/Ids), the intrinsic gain (gmRo), the intrinsic capacitance, the intrinsic resistance, the transport delay and, the inductance of the device have been analyzed for analog and RF performance analysis. Analysis suggested that the average intrinsic gain, gm/Id and gm are increase by 22.988%, 16.10% and 27.871% respectively compared to the underlap single-material gate U-DG NMOSFET.