CMP Consumable Testing

FIGURE 4.23 Removal rate and pad condition dependence on conditioner age (from Ref. 25). 

CMP consumable quality and performance need to be consistent with the specifications, which is highly critical to have significant process control and yield. In this regard, tribometrology can be utilized to test the consumable quality and functionality. 

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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). 

Design of the experiment. Test wafers or consumables are designed to assess the polishing performance and enable the study of target factors in a CMP process. Process parameters are selected to explore the target polishing requirements. 

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