Dual frequency silicon nitride film of low thermal budget for pre-metal dielectric applications in sub-0.25 μm devices

Dual frequency (Bottom Power) nitride films fabricated by Plasma Enhanced Chemical Vapor Deposition (PECVD) process are extensively studied for pre-metal dielectric application. The films share the same advantages as single frequency process in its low hydrogen content due to the process temperature (550°C), which is much higher than the conventional PE nitride. The addition of low frequency power considerably improved the film step coverage and conformality. The MF nitride film also demonstrated outstanding film integrity in the pin-hole test. One of the usual concern about PECVD process is plasma induced damage. Our in-house non-contacting monitor result shows very uniform plasma distribution and minimum amount of surface charging on the wafer. All our findings proves that high quality silicon nitride films generated by dual frequency PECVD method provide an low thermal budget solution for Pre-Metal Dielectric applications in Sub-0.25 μm technology