Analysis of a SiGe MOSFET at 22nm

The present paper proposes a novel concept which can successfully reduce threshold voltage and increase switching speed of a conventional MOSFET. The proposed structures have been incorporated with a silicon germanium (SiGe) layer as a channel at the 22 nm technology node. Also, extensive analyses have been done to study the effects of replacing conventional polysilicon by graded dopent profile polysilicon, use of a high-k/silicon dioxide stack as a dielectric with graded dopent profile polysilicon and by using a high-k/silicon dioxide stack as a dielectric with a metal gate. Hafnium dioxide is used as a high-k material. Silvaco Athena and Atlas simulators are used for simulation as well as for finding electrical characteristics of the structures. For all the proposed structures two important parameters are studied in detail, threshold voltage and subthreshold slope. Comparing the three structures, it can be seen that using the high-k/silicon dioxide stack as a dielectric with a metal gate yields the best threshold voltage as well as good subthreshold slope which is directly related to the switching behaviour of the device. The required fabrication aspects of the modelled structures are also elaborated in detail.