A method for semiconductor manufacturing is disclosed. The method includes receiving a device having a first surface through which a first metal or an oxide of the first metal is exposed. The method further includes depositing a dielectric film having Si, N, C, and O over the first surface such that the dielectric film has a higher concentration of N and C in a first portion of the dielectric film near the first surface than in a second portion of the dielectric film further away from the first surface than the first portion. The method further includes forming a conductive feature over the dielectric film. The dielectric film electrically insulates the conductive feature from the first metal or the oxide of the first metal.