PE-CVD OF FLUOROCARBON/SILICON OXIDE COMPOSITE THIN FILMS FROM TFE AND HMDSO

摘要

Fluorocarbon / silicon oxide composite thin films were prepared, expecting higher thermal stability, by mixing hexamethyldisiloxane (HMDSO, (CH_3)_3-Si-O-Si-(CH_3)-3) with tetrafluoroethylene (TFE, CF_2=CF_2) using an RF( 13.56 MHz) PE-CVD method for the purpose of application to low-k IMDs. Structure of the deposited films was investigated by XPS and FT-IR. Film composition can be changed gradually from fluorinated carbon to organic siloxane by changing the HMDSO mixing ratio. The films possessed dielectric constants less than 2.5 for HMDSO mixing ratios less than 10%. Thermal treatment of the films revealed that C-F_n, Si-O-Si, Si-CH_3)_n and Si-(CH_2)_n-Si bonds were stable to 400°C, but C-H_n bonds were not. In situ gas-phase FT-IR spectroscopy was performed on the TFE/HMDSO plasma to help determine reaction mechanisms.