Material Removal Rate and Selectivity

FIGURE 7.18 Zeta-potential data obtained from Brookhaven s Zeta Pals Electrokinetic Analyzer showing negative charge over a wide pH range (from Ref. 110). 

FIGURE 7.20 Removal rate versus downforce on 8 Cu blanket test wafers polished at 75/65 rpm table/carrier speed and 200ml/min slurry flow rate on Strasbaugh u-Hance polisher. Diamond data points indicate the removal rate values with the organic particles, and square data points denote removal rate values for silica particles, both polished under identical formulation and abrasive concentration (from Ref. 110). 

TABLE 7.3 Removal Rate of 8 Blanket Test Wafers of Different Snbstrates at Similar Process Conditions with the Organic Abrasive Slurry [109]. 

As the abrasive particles are specifically designed to interact with copper surface, the removal rate on the barrier and dielectric materials are very low (Table 7.3). This will allow longer overpolishing without incurring significant erosion. 

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