Determining the effects of slurry surfactant, abrasive size and abrasive content on the tribology and kientics of copper CMP

Eight hydrogen peroxide based slurries containing colloidal silica abrasives of varying diameters and contents were used to investigate the effects of slurry surfactant, abrasive size and abrasive content on the characteristics of copper CMP. One-half of formulations also contained equal amounts of surfactant. Abrasive content had no effect on the lubrication mechanism. The lubricating nature of the fatty components of surfactants reduced COF. This reduction was especially pronounced with smaller size abrasives due to an increased contact area, Complex interactive effects were observed among various parameters such as the product of applied pressure and sliding velocity, abrasive size and the presence of the surfactant. No correlation was observed between COF and removal rate, which was contrary to previously reported results regarding Interlayer Dielectric (ILD) CMP. Spectral analysis of the raw frictional data showed good correlation between removal rate and the total amount of mechanical energy of the process caused by stick-slip phenomena. Moreover, strong evidence of an Arrhenius-type relationship between removal rate and temperature was observed, indicating that copper CMP was strongly influenced by temperature.