bac, W

ed in ble o particles (either alumina or fumed silica). The addition of Surface & Coatings Technology 1mechanisms proposed [1–4]. In order to successfully inte-grate Cu into ICs, an appropriate diffusion barrier layer, such as Ta [5–8], Ta2N [7,8], TaN [8] or amorphous Ta– Si–N [6], all of which are thermodynamically stable with respect to Cu, is usually applied. However, studies on the CMP behavior of Ta and its nitrides are fewer [9–12] than those of Cu. The effects of abrasive particles and oxidant addition on ly. However, the addition of an oxidant, such as Fe(NO3)3 or Cu(NO3)2, among others, reduced the Ta polishing rate in DI water that contained abrasive particles. The adverse effect of adding H2O2, which reduced the polishing rate in Ta CMP, has also been observed in DI water that contained fumed amorphous silica. This result was in contrast to that found for Cu CMP [10]. Li and Babu [10] indicated that the addition of H2O2 presumably caused the formation of a hardrizing the surface on a global scale. Much effort has been devoted to the study of Cu CMP with some different 3 wt. % alumina and Aerosil silica abrasive particles raised the polishing rate to 67 nm/min and 74 nm/min, respective-Chemical–mechanical polishing (CMP) is a promising means of technique for removing excess copper and plana-Al2O3, either in DI water or in the 0.01 M citric acid + 9 vol. % H2O2 slurries. The surface roughness of Ta after CMP in 0.01 M citric acid + 9 vol. % H2O2 slurries was higher than that in DI water base slurries when the Al2O3 content was low. A significant reduction in surface roughness combined with a high removal rate could be obtained if the Al2O3 content in the 0.01 M citric acid + 9 vol. % H2O2 slurries was increased to above 10 wt.%