Classical and Quantum Mechanical Models Studies of Sub-32 nm MOSFET Devices

Abstract

Scaling down of MOSFETs continuously has made them faster with increase in chip design complexity. As the gate length is going reducing, short channel effects (SCE) are more pronounced. These Short channel effects subsequently degrades the performance characteristics of the MOSFETs by diminishing the control of gate over channel. In conventional techniques, control of gate voltage over channel is done through increasing the gate capacitance (Cg) by reducing the oxide thickness, but this results in increase in leakage current which increases power dissipation. A Cogenda Visual TCAD tool is used to design and simulate MOSFET structure. Double gate MOSFETs is used to reduce these SCEs. In this work a 32 nm single gate MOSFET and 32 nm, 20 nm, 14 nm, 7 nm double gate MOSFETs are designed and their characteristics are compared. Simulations of classical and quantum modelling exhibits the increase in the threshold voltage. The I_on to I_off ratio, transconductance, subthreshold slope, threshold voltage, drain induced barrier limiting of all the MOSFETs are calculated. Quantum effects are taken into the consideration which results in reduction of leakage current to the greater extent. Due to the quantum effects the drive current obtained is less as compared to the drive current obtained from classical modelling. Also accurate DIBL and optimum value of subthreshold slope is attained when quantum effects are taken into consideration. Quantum confinements of MOS devices are inspected in this work by making comparison between the quantum and classical models.