Nanocatalyst-induced hydroxyl radical (^·OH) slurry for tungsten CMP for next-generation semiconductor processing

Chemical mechanical polishing (CMP) is one of the important steps that involves during fabrication of semiconductor devices. This research highlights the importance of tungsten (W) polishing slurries consisting of a novel nonionic, heat-activated FeSi nanocatalyst on the performance of W chemical mechanical polishing. The results obtained from the polishing data showed a higher W removal rate of 5910 Å/min with a slurry consisting of FeSi nanocatalyst at a polishing temperature of 80 °C. The increase in W polishing rate using FeSi slurry was explained on the basis of formation of a thicker oxide layer (WO₃) due to the interaction between the W surface and hydroxyl radicals (^·OH) generated via the reaction between FeSi and hydrogen peroxide at 80 °C. Higher ^·OH generation and increase in oxygen depth profile of W film were confirmed by UV–Vis spectrometer and AES analysis, respectively. Compared to Fe(NO₃)₃ catalyst, the slurry with FeSi showed a higher static etch rate at 80 °C. Potentiodynamic polarization results obtained using FeSi slurry showed thicker WO₃ passivation layer as compared to the slurry with Fe(NO₃)₃. The increase in the polishing rate of W CMP using slurry with FeSi nanocatalyst can be essentially attributed to the generation of much stronger oxidant ^·OH due to its increased catalytic effect at a high polishing temperature of 80 °C.