An amorphous SiCOF film with low dielectric constant prepared by plasma-enhanced chemical vapor deposition

Amorphous SiCOF films with a low dielectric constant and good moisture resi stance were deposited in a plasma-enhanced chemical vapor deposition (PECVD ) system using a C4F8/TEOS/O-2 mixture. The dielectric constant can be redu ced to 2.6 when the flow rate of C4F8 increases to 30 seem. The breakdown s trength of the deposited film can be improved by increasing the C4F8 flow r ate. Through Fourier transform infrared spectroscopy (FTIR) and X-ray photo electron spectroscopy (XPS) analyses, the structural changes caused by C do ping are discussed in detail. There are C-F bonds and cross-link C-C bonds, in addition to Si-O and Si-F bonds, in the films. It was found that carbon dopant in the film results in a decrease in the Si-O-Si bond angle and an increase in the Si-O bond length. These changes are relative to the redistr ibution of partial charge on Si-O-Si due to carbon doping. Furthermore, the C-F bonds in a-SiCOF film will reduce Si-OH components in the film and imp rove the moisture resistance of the film due to the hydrophobic property of the C-F bond. (C) 2001 Elsevier Science B.V. All rights reserved.