Abstract
With the scaling down of the ULSI (Ultra-large-scale Integrated) circuits, thinner dioxide thickness becomes more and more important for next generation. However, the physical limitation of the insulator also becomes more serious. Leakage current is the most important factor as the ultra thin dioxide being implemented. In this work, three types of gate dioxides are studied. These samples we used are 40 angstroms dry-oxygen-grown, 40 angstroms N2O purged-dry-oxygen-grown, and 25 angstroms N2O purged-dry-oxygen-grown dioxides.The simulation of 40 angstroms sample is focused on Fowler -Nordheim tunneling, and which of 25 angstroms sample is focused on direct tunneling. According to the polarity dependence of experimental curves, it is observed that the surface potential effect on positive gate bias measurement is important. It is necessary to use surface potential for estimating the oxide field under inversion mode. The leakage current is separately dominated by Fowler-Nordheim tunneling ( for 40 angstroms dioxide ) and Direct tunneling ( for 25 angstroms dioxide ). For the accumulation mode curves, the leakage current is simulated without considering surface potential. Also, it is observed that the dominated mechanism of 40 angstroms dioxide is Fowler-Nordheim tunneling and which of 25 angstroms dioxide is Direct tunneling. Moreover, the tunneling electron's effective mass of 40 angstroms dioxide is around 0.45m0, and that of 25 angstroms dioxide is 0.58 m0