Novel diamond disc diagnostic method based on 'dry' coefficient of friction measurements

This paper presents an accurate, consistent and rapid novel method for determining the dry coefficient of friction of conditioner discs. The first part of the study dealt with characterizing 3 diamond discs (i.e. two 'known good' and one 'known bad' diamond discs with the same product number) on top of dry polycarbonate sheets. Results showed that the coefficient of friction of the 'known bad' disc was significantly higher than the two 'known good' discs. As further evidence, primary and secondary vibrational frequency amplitudes from spectral analysis of shear forces showed the 'known bad' disc to have lower average values compared to the two 'known good' discs. The second part of the study had to do with determining whether dry coefficient of friction and total surface area of the furrows generated by the active diamonds on top of dry polycarbonate sheets could be correlated. Results show that coefficient of friction increased with total surface area of the furrows. For diamond disc conditioner manufacturers, this work should provide useful information and rapid disc assessment for improving existing manufacturing processes or for developing new products. The work also underscores the importance of screening diamond conditioner discs before being used in IC manufacturing to improve productivity and COO in CMP modules.