High removal rate slurries

The results of the CMP field evaluation are shown in Figure 3.12, and the removal rates of oxide and nitride and the selectivity of slurries are presented in Table 3.2. The slurries prepared in neutral and alkaline suspensions had high removal rates of PETEOS and low WIWNU. 

Cu CMP slurries for through sihcon vias (TSVs) with very high removal rates and high selectivity to oxides like TEOS have been developed with silica abrasive particles as well as so-called particle-free slurries (e.g. Reactive Liquid from Dow Chemicals). Cu barrier slurries with tunable selectivity to TaN and tetraethylorthosilicate (TEOS)... 

In this chapter, we derive and apply to data a simple two-step model that involves a chemical step followed by a mechanical removal step. The model is abstract in the sense that most of the specifics of the slurry composition or of the chemical reaction involved are not given in any detail. Although this appears to be a disadvantage, it is necessary for the application of the model to the analysis of removal rates from proprietary slurries whose compositions cannot be directly investigated. When applied as a compact formula, the model can provide a highly accurate description of removal rate variations as a function of polishing pressure and sliding speed. This then makes it possible to extract the relative contributions of chemical and mechanical processes to removal and to confidently interpolate or extrapolate rates based on the calibration data. 

CMP potentiodynamic measurements. Their work showed a large decrease in the corrosion current at 1 wt % of the oxidizer concentration, indicating the formation of a passivating film. AES measurements confirmed the formation of a high oxygen content film with a thickness of 1.5 nm. The addition of 3 wt % alumina to the slurry showed a twofold increase in the removal of copper when compared to the abrasive-free systems. The material removal rate peaked when using 2 wt % oxidizer. 

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