Analytical Model of Subthreshold Swing for Junctionless Double Gate MOSFET Using Ferroelectric Negative Capacitance Effect

Abstract

An analytical Subthreshold Swing (SS) model is presented to observe the change in the SS when a stacked SiO2-metal-ferroelectric structure is used as the oxide film of a JunctionLess Double Gate (JLDG) MOSFET. The SS of 60 mV/dec or less is essential to reduce power dissipation while maintaining transistor performance. If a ferroelectric material with Negative Capacitance (NC) effect is used, the SS can be reduced below 60 mV/dec. The analytical SS model of the ferroelectric NC FET presented to analyze this was in good agreement with the SS derived from the relation between the drain current and gate voltage, using 2D potential distribution. As results were derived from the analytical SS model, it was found that it is possible to obtain an SS of 60 mV/dec or less even at 15 nm channel length by adjusting the thicknesses of the silicon channel, SiO2, and ferroelectric. In particular, the change in SS according to the ferroelectric thickness was saturated as the thickness of SiO2 increased and was almost constant as the thickness of the silicon channel decreased. ABSTRAK: Model Ayunan Subambang (SS) analitikal dibentangkan bagi melihat perubahan pada SS apabila struktur feroelektrik-logam-SiO2 bertindan digunakan sebagai filem oksida bagi MOSFET Dua Get Tanpa Simpang (JLDG). SS 60 mV/dec atau kurang adalah penting bagi mengurangkan pelesapan kuasa sambil mengekalkan prestasi transistor. Jika bahan feroelektrik dengan kesan Kapasitans Negatif (NC) digunakan, SS dapat dikurangkan bawah 60 mV/dek. Model SS analitikal feroelektrik NC FET yang digunakan bagi kajian ini adalah sesuai dengan SS yang diperoleh daripada hubungan antara arus serapan dan voltan get, menggunakan edaran potensi 2D. Dapatan terbitan melalui model SS analitikal, mendapati bahawa adalah mungkin bagi mendapatkan SS pada 60 mV/dek atau kurang walaupun panjang laluan adalah 15 nm dengan melaraskan ketebalan saluran silikon, SiO2, dan feroelektrik. Terutama apabila perubahan ketebalan feroelektrik SS adalah tepu ketika ketebalan SiO2 meningkat, dan hampir malar apabila ketebalan saluran silikon berkurang.