Premetal planarization using spin-on-dielectric

A silicate-type spin-on-glass (SOG) was used to planarize topography prior to metal deposition. SOG was chosen for this application because of the simplicity associated with processing. The topography smoothing capability was shown to be comparable to that of flowed CVD oxide. It was found that curing the SOG in a dry oxygen ambient caused the film to densify poorly and to result in inferior dielectric properties. Performing the cure in a steam ambient, however, resulted in films with dielectric properties similar to those of CVD oxide films. This dielectric was used successfully in a 1.0-μm double-level metal process without degrading device performance. It was shown that the film does not need to be fully densified in order to be used in this application. Temperature/humidity testing showed no anomalous effects to devices due to moisture absorption or film delamination