Effects of N2O plasma treatment on perhydropolysilazane spin-on-dielectrics for inter-layer-dielectric applications

• Perhydropolysilazane (PHPS) layer is evaluated as a Si interlayer dielectric.
• Examine effects of the N2O plasma treatment (PT) on PHPS spin-on-dielectrics (SODs)
• Significantly improved metal contact resistances are achieved using the N2O PT.
• Contact resistance enhancement by PT is due to the minimized carbon contamination.

Effects of the N2O plasma treatment (PT) on perhydropolysilazane spin-on-dielectric (PHPS SOD) were examined as potential inter-layer-dielectrics (ILDs) for sub-30 nm Si circuits. The spin-coated PHPS (18.5 wt.%) ILD layers converted at 650 °C were integrated with the 0.18 μm Si front-end-of-the line process. A modified contact pre-cleaning scheme using N2O PT produced more uniform and stable contact chain resistances from the SOD ILDs than the case of pre-cleaning only by buffered oxide etcher. Our analysis shows that this enhancement is due to the minimized carbon contamination on the PHPS side-wall surface densified by PT.