Effect of Mechanical and Chemical Wear on Consistency of Conditioning in Diamonds

Abstract

We evaluated the effects of the edge degradation of diamonds in terms of their cutting ability from the viewpoint of mechanical, chemical and chemical-mechanical wear in chemical-mechanical polishing (CMP) systems for high-volume manufacturing. The results showed that both micro-chipping on the cutting edges of diamonds caused by a mechanical shock test and the rounding off of the sharp edges of diamonds in a marathon wear test degraded the pad cut rate, while no adverse effects on the cutting ability were observed during an acidic slurry immersion test. We also examined in situ coefficient of friction (COF) monitoring for use in identifying the tribology of the pad conditioning. Furthermore, we demonstrated the usefulness of measuring the height ratio of the asperity called “top surface area (TSA) ratio” as an appropriate topographical parameter to study the dependence of COF during conditioning on the decay of the tungsten removal rate. We presented a clear correlation between the pad cut rate degradation and the TSA ratio after CMP in order to elucidate an increase in the conditioning COF related to truncation of the asperity tip by wear and plastic deformation.