The impact of H-2/N-2 and NH3 plasma treatments on the properties of low-dielectric-constant (low-k) carbon-doped silicon oxide (CDO) film, deposited by plasma-enhanced chemical vapor deposition, has been investigated. The thermal stability and the effect of moisture penetration on low-k films have also been evaluated. It is found that H-2/N-2 and NH3 plasma treatments of low-k films result in some loss of C content and increase in moisture uptake. This increases the k value and leakage current of the film. The H-2/N-2 and NH3 plasma treatments do not add any N content in the films. Therefore, it does not cause the resist contamination of chemically amplified-type photoresists. High thermal stability of the low-k CDO material is confirmed by isothermal thermogravimetric analysis of the low-k CDO powder and there is no weight loss or change of composition of the low-k CDO film after seven thermal cycles at 425degreesC for 1 h in N-2 ambient. A pressure cooker test of the film carried out at similar to2 atm, 120degreesC, and 100% relative humidity for 24 h has been found to increase the k value by 7% and leakage current by two orders of magnitude. (C) 2004 The Electrochemical Society.