Coefficient of Friction and Acoustic Emission Signal

FIGURE 4.33 Coefficient of friction and acoustic emission signal measurements indicating low-k delamination (from Ref. 36). 

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The coefficient of friction and acoustic emission signal can be effectively utilized for functional testing of consumables. An example of such a utility is illustrated in Fig. 4.26. For a quantitative, fast, and inexpensive estimate of the functional properties of two different products from a manufacturer, the slurry samples were tested on a CMP tester equipped with capability for continuous acquisition of the frictional and acoustic signals. The collected signals allow the determination of three important functional parameters, namely, time of complete tungsten removal, time of complete underlayer removal, and intensity of polishing (characterized by the level of acoustic signal). 

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