Effect on In-situ H2 Plasma Treatment of ZrO2 Gate Dielectric Deposited by Plasma Enhanced Atomic Layer Deposition Method

Abstract

As the metal oxide semiconductor device continues scale down, the high-k gate dielectrics become one of the solutions in providing increased capacitance and reduced leakage currents without significantly increasing the actual equivalent oxide thickness (EOT) of gate dielectrics. Among the high-k materials, ZrO2 is considered as one of the alternatives to SiO2 gate dielectric due to the relatively high dielectric constant (~25), low leakage current and its compatibility with the manufacturing of integrated circuits.1 Here, we focus on the in-situ H2 plasma effect on ZrO2 gate dielectric deposited by plasma enhanced atomic layer deposition (PEALD) method. ZrO2 were deposited on p-type Si (100) substrates at 200-300°C using t-butoxide as Zr precursor and oxygen as reactant gas at the process pressure of about 1 Torr. Initial native oxide layer was removed by in-situ hydrogen plasma treatment before ZrO2 deposition at the same processing temperature. Oxygen reactant gas was introduced both as in gas and plasma states. About 1000A layer of Platinum (Pt) as gate electrodes were deposited by e-beam evaporator. The electrical properties of this MOS capacitor were measured after post metal annealing. The physical and chemical characteristics of ZrO2 film were analyzed by cross-sectional transmission electron microscope, atomic force microscope, Auger electron spectroscopy, X-ray photoelectron spectroscopy and Rutherford backscattering spectroscopy. The results of electrical properties and reliability characteristics including EOT, hysteresis, leakage current and capacitance were measured by I-V and C-V. This paper presents the plasma effect on ZrO2 films deposited by PEALD method and its potential applications for gate dielectric in ultra large-scale integrated circuit devices. 1W. Qi, R. Nieh, B. H. Lee, L. Kang, Y. Jeon and J. C. Lee, Appl. Phys. Lett., 77, 3269-3271 (2000).