Characteristics of SiOC(-H) Thin Films Prepared by Using Plasma-enhanced Atomic Layer Deposition
- Low dielectric constant SiOC(-H) thin films were prepared on p-type Si(100) substrate by using plasma-enhanced atomic layer deposition (PEALD) with trimethylsilane (TMS; (CH3)3SiH) and oxygen gas as precursors and Ar as a purge gas. The adoption of 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 dielectric properties was studied. The rf power from 100 W to 500 W was applied to the PEALD system to generate plasma. The films were analyzed by using Fourier-transform infrared (FTIR) spectroscopy, C-V and I-V measurements. FTIR studies were carried out in the absorbance mode in the range of 700 to 4000 cm-1, which showed various bonding configurations, such as Si-O-Si(C), Si-CH3, -OH and CHn bonds, in the films. As the rf power increased the absorption peaks corresponding to Si-O-Si and Si-O-C bonds become sharper, at the same time, the former shifted towards lower wave number region (red shift). The dielectric constant 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 ¡10-8 A/cm2 at 1 MV/cm, respectively. Using the optimized process condition, the evaluation of PEALD method applied to SiOC(-H) film deposition was performed. It has been shown that the PEALD method without heat treatment for SiOC(-H) film deposition is not only comparable with PECVD method with heat treatment or UV irradiation, but also applicable to a new application which required a low temperature process.
- Keywords: low-k materials, PEALD, OES, FTIR, XPS, C-V measurement