Thermal Stability and Scalability of Mictamict Ti–Si–N Metal–Oxide–Semiconductor Gate Electrodes

Abstract

The annealing temperature and thickness dependences of electrical properties of mictamict Ti–Si–N gate metal–oxide–semiconductor (MOS) capacitors, and their relationships with the crystalline structure were investigated. The nanocrystallites in mictamict Ti–Si–N films sputtered in over 3.0% N2 ambient hardly grow even after postdeposition annealing (PDA) at temperatures below 900 °C. As the N2 concentration increases up to 3%, the resistivity of the Ti–Si–N films increases owing to an increase in the amount of Si3N4 components and the development of the amorphization. On the other hand, the resistivity decreases with increasing N2 concentration above 3%. This is attributed to the formation of Ti3N4 components, as revealed by X-ray photoelectron spectroscopy (XPS) analysis. The changes in resistivity and effective work function are also extremely small. Additionally, even when the Ti–Si–N film thickness is reduced to 5 nm, the Pt/Ti–Si–N stacked gate electrode maintains almost the same effective work function (4.6 eV).