Performance investigation of high-k dielectric material for shorter channel length MOSFET / Fatin Antasha Anizam

The objective of this study is to investigate the performance of MOSFET using different types of high-k dielectric material which is silicon nitride (Si3N4), aluminium oxide (Al203) and hafnium oxide (HfO2 ). The purposed of this study is to find a new dielectric material that can replace silicon dioxide (SiO2) since it has problems related to short channel effects (SCEs). This SCEs occur when oxide layer became thinner and gate length become shorter. MOSFET structure was fabricated and simulated using Silvaco TCAD tool. Several parameters which is oxide thickness, tox and channel length, lg was varied to investigate whether the high-k material can overcome the SCE that occur in the MOSFET device using SiO2 as dielectric material. Different types of material (polysilicon and germanium) use to fabricate gate also being varies since it can lead to reducing the SCEs. The overall performance of the MOSFET is evaluated based on the current-voltage (/ — V) characteristics. Result obtained show that MOSFET with HfO2 as dielectric material has high drive current and low leakage current while the presence of Ge as gate material reduce leakage current by a factor of 0.55 from the conventional MOSFET. Therefore, combination of HfO2 and Ge in MOSFET structure has the best performance compared to SiO2 and polysilicon because it produces smaller leakage current and smaller Vth when shrinking the device sizes, hence reducing SCEs.