Gate leakage current of NMOSFET with ultra-thin gate oxide

Abstract

As dimensions of the metal-oxide-semiconductor field-effect transistor (MOSFET) are scaling down and the thickness of gate oxide is decreased, the gate leakage becomes more and more prominent and has been one of the most important limiting factors to MOSFET and circuits lifetime. Based on reliability theory and experiments, the direct tunneling current in lightly-doped drain (LDD) NMOSFET with 1.4 nm gate oxide fabricated by 90 nm complementary metal oxide semiconductor (CMOS) process was studied in depth. High-precision semiconductor parameter analyzer was used to conduct the tests. Law of variation of the direct tunneling (DT) current with channel length, channel width, measuring voltage, drain bias and reverse substrate bias was revealed. The results show that the change of the DT current obeys index law; there is a linear relationship between gate current and channel dimension; drain bias and substrate bias can reduce the gate current.