Feasibility of real-time detection of abnormality in inter layer dielectric slurry during chemical mechanical planarization using frictional analysis

Material removal rate, coefficient of friction, shear force and variance of shear force of pure and contaminated slurries are studied using spectral analysis of the frictional force. Larger abrasive particles are introduced into commercially available inter layer dielectric chemical mechanical planarization slurry to explore this effect. Results show that trace amounts of larger abrasive particles are transported effectively to the pad-wafer region during polishing. With certain type of consumables investigated in this study, results indicate that contaminated slurry does not significantly change removal rate, however it induces significantly higher coefficient of friction, shear force and variance of shear force than pure slurry. Spectral analysis based on the raw shear force data is employed to elucidate the fundamental physical phenomena during inter layer dielectric chemical mechanical planarization. Fast Fourier Transformation is performed to convert the shear force data from time domain to frequency domain. The energy distribution of polishing using pure and contaminated slurry is quantified to elucidate the effect of trace amount of larger particles. This work also underscores the importance of real-time detection on chemical mechanical planarization process to detect slurries abnormality.