Deposition of SiO2:F:C with low dielectric constant and with high resistance to annealing

SiO2:F:C films were deposited using a plasma-enhanced chemical vapor deposition (PECVD) technique from SiH4/O2/CF4/CH4 mixtures. Increasing amount of carbon were introduced to the SiO2:F films by changing the CH4 flow rate, [CH4], while keeping constant other conditions such as rf power and deposition temperature, TD. It was found that the addition of CH4 decreases the dielectric constant, k, from 3.36 for [CH4] = 0 sccm to 2.95 for [CH4] = 8 sccm. For the [CH4] condition where the film has a lowest k, the deposition temperature and rf power were optimized by depositing films using different values of TD and rf power The k for films in the new series as well as the stress and water absorption was investigated. Results show that the dielectric constant further decrease up to 2.85. Some films were then annealed from 400 - 800°C and it was found that the k for films deposited with higher [CH4] has a better stability with respect to annealing up to a temperature of 600°C.