Competitive Surface Adsorption Behavior of Corrosion Inhibitors

7 COMPETITIVE SURFACE ADSORPTION BEHAVIOR OF CORROSION INHIBITORS 

As shown in Fig. 8.4, to form an effective passivating film on copper, a corrosion inhibitor must adsorb onto the surface. The adhesion to the copper surface must be strong enough to protect against the shear force impinged by slurry flow. The coordinate bond found in a typical copper(I) or copper(II) complex is usually sufficient to serve as an anchor. The static charge attraction between a surfactant and a charged surface may be too weak to perform such 

FIGURE 8.16 Concentration of (a) free inhibitor in solution and (b) adsorbed inhibitor onto Cu particles after surface adsorption in various amounts of copper particles. 

The water solubility profiles of corrosion inhibitors are also very helpful in predicting the optimum pH for the CMP slurry to give the best performance and design matching post-CMP cleaning solution. For example, according to Fig. 8.17a, BTA- containing slurry will yield the best results at pH 4-7 in terms 

Corrosion inhibitors are an important chemical constituent of Cu CMP slurry. The critical performance of a slurry such as static etch rate, material removal rate, and post-CMP defect counts are greatly influenced by the concentration and the structure of the inhibitor used in the slurry. BTA is proven to be an effective corrosion inhibitor for Cu CMP especially in nonacidic medium. 

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