Modeling and simulation of cylindrical surrounding double-gate (CSDG) MOSFET with vacuum gate dielectric for improved hot-carrier reliability and RF performance

Abstract

We present modeling and simulation of a cylindrical surrounding double-gate (CSDG) metal---oxide---semiconductor field-effect transistor (MOSFET) with vacuum gate dielectric instead of silicon dioxide, revealing some improvement in hot-carrier reliability. The CSDG MOSFET incorporates an extra inner control gate compared with the cylindrical surrounding gate (CSG) MOSFET, resulting in improved drain current in the channel. The radiofrequency (RF) performance of the CSDG MOSFET is obtained and compared for different dielectrics such as vacuum, silicon dioxide, and high-k material. The RF performance of the CSDG MOSFETs is evaluated on the basis of transconductance, capacitance, cutoff frequency, and drain current. Also, the surface potential and electric field are evaluated analytically at higher drain bias. It is shown that, with decreasing gate dielectric constant, the threshold voltage decreases while hot-carrier parameters such as the electron temperature are reduced at the drain side.