PECVD Silicon Nitride for Damascene Applications

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PECVD Silicon Nitride for Damascene Applications Albert Lee, Nagarajan Rajagopalan, Maggie Le, Bok Heon Kim, and Hichem M’Saad Dielectric Systems & Modules Product Business Group, Applied Materials Inc., Santa Clara, CA 95054, U.S.A. ABSTRACT A PECVD silicon nitride film, Damascene Nitride™, is deposited in a PECVD chamber with a hollow cathode faceplate using silane and ammonia as precursor gases. Various techniques (FTIR, RBS-HFS, SIMS, TDS and BTS) were used to characterize the structure, composition, density and wet etch rate of the film. FTIR analysis indicates that Damascene Nitride is very similar to a high density plasma (HDP) nitride film. HFS analysis shows the film’s hydrogen content to be 13%, ~6% less than other PECVD nitride films, leading to a 20% improvement in etch selectivity to FSG. The film wet etch rate is 2 times slower than that of other PECVD nitrides, and the dielectric constant k was measured to be 6.8, which is lower compared to other PECVD nitrides and HDP CVD nitrides where k ~ 7.0 and 7.5, respectively. SIMS analysis shows that Cu diffusion is