Method and apparatus for depositing a film

A method of depositing a film, such as a barrier layer, on a substrate using a gaseous mixture including a hydrocarbon-containing gas and a silicon-containing gas. Suitable hydrocarbon-containing gases include alkanes such as methane (CH4), ethane (C2H6), butane (C3H8), propane (C4H10), etc. Suitable silicon-containing gases include silanes such as monosilane (SiH4). The method generally comprises providing a suitable gaseous mixture to the chamber, generating a plasma from the gaseous mixture, and depositing a film onto the substrate using the plasma. In a preferred embodiment, the film is deposited in a high-density plasma chemical vapor deposition (HDP-CVD) system. The gaseous mixture typically includes a silicon containing gas, such as an alkane, and a hydrocarbon containing gas, such as a silane. Embodiments of the method of the present invention can integrated stack structures having an overall dielectric constant of about 4.0 or less. Such a structure may include a barrier layer having a dielectric constant of 4.5 or less.