Characteristics of SiOC(-H) Thin Films Prepared by Using Plasma-enhanced Atomic Layer Deposition

Abstract

Low-dielectric-constant SiOC(-H) thin films were prepared on p-type Si(100) substrates by using plasma-enhanced atomic layer deposition (PEALD) with trimethylsilane (TMS; (CH(3))(3)SiH) and oxygen gas as precursors and Ar as a purge gas. The adoption of the atomic layer deposition (ALD) method to deposit low-k materials is a challenge to achieve high-quality films and low-temperature process conditions. The effect of the radio-frequency (rf) power on the structural and the dielectric properties was studied. RF powers from 100 W to 500 W were applied to the PEALD system to generate the plasma. The films were analyzed by using Fourier-transform infrared (FTIR) spectroscopy and C-V and I-V measurements. FTIR studies were carried out in the absorbance mode in the range of 700 to 4000 cm(-1), and showed various bonding configurations, such as Si-O-Si(C), Si-CH(3), -OH, and CH(n), bonds, in the films. As the rf power was increased, the absorption peaks corresponding to the Si-O-Si and the Si-O-C bonds become sharper; at the same time, the former shifted towards lower wave number (red shift). The dielectric constants of the films were investigated using a Al/SiOC(-H)/p-Si MIS structure. The measured dielectric constant and leakage current density were 2.3 and similar to 10(-8) A/cm(2) at 1 MV/cm, respectively. Using the optimized process conditions, we evaluated the PEALD method applied to SiOC(-H) film deposition. The PEALD method without heat treatment for SiOC(-H) film deposition has been shown not only to be comparable to the PECVD method with heat treatment or UV irradiation but also to be applicable to a new applications requiring a low-temperature process.