Growth and characterization of silicon nitride films on various underlying materials

Characteristics of silicon nitride (SiNx:H) films, grown by plasma enhanced chemical vapor deposition (PECVD) on various metals such as Ta, IrMn, NiFe, Cu, and CoFe at various temperatures down to 100 degreesC, were studied using measurements of BHF etch rate, surface roughness and Auger electron spectroscopy (AES). The results were compared with those obtained for SiNx:H films on Si. The deposition rate of SiNx:H films increased slightly as deposition temperature decreased, and showed a weak dependence on the underlying materials. The surface of the nitride films deposited on all underlying materials at lower temperatures (below 150 degreesC) became rougher. In particular, a bubble-like surface was observed on the nitride film deposited on NiFe at 100 degreesC. At higher deposition temperatures (above 200 degreesC), SiNx:H films on all the above metals had small RMS values, except for films on Cu which cracked at 250 degreesC. BHF (10 : 1) etch rate increased dramatically for nitride films deposited below 150 degreesC. For different underlying films, the BHF etch rate was quite different, but exhibited the same trend with decrease in deposition temperature. AES measurements showed that Si and N concentrations in the SiNx:H films were only slightly different for the various deposition temperatures and underlying materials. AES depth profile of nitride films indicated that both surface 0 content and the depth of oxygen penetrating into SiNx:H increased for low temperature-deposited films. However, there was no observed oxygen signal from within the films, even for films deposited at 100 degreesC, and both Si and N concentrations were uniform throughout the film.