An important component of the slurries used in chemical mechanical planarization (CMP) is an appropriately chosen corrosion/dissolution inhibitor, which facilitates selective material removal from protrusions while protecting recessed regions of the surface. The present work demonstrates the utility of two environmentally benign anionic surfactants, sodium dodecyl sulfate (SDS) and ammonium dodecyl sulfate (ADS) as dissolution inhibitors. Using a standard slurry (1 wt% glycine with 5 wt% H 2 O 2 at pH ‫ס‬ 4.0) typically used for Cu CMP and combining measurements of open circuit potentials and contact angles with those of Cu removal rates, we show that both SDS and ADS suppress chemical dissolution and polish rates of Cu. The dissolution inhibition efficiencies of ADS and SDS measured in these experiments are found to be superior to those of benzotriazole (BTA), a traditional inhibiting agent used for copper CMP.

We investigate the role of -NH 2 and -COOH functional groups of complexing agents in H 2 O 2 -based slurries in controlling copper ͑Cu͒ removal rates. Slurries containing complexing agents with two of the same functional groups ͑succinic acid: HOOC-CH 2 CH 2 -COOH, ethylene diamine: H 2 N-CH 2 CH 2 -NH 2 ͒ and a complexing agent containing one each of the functional groups ͑␤-alanine: H 2 N-CH 2 CH 2 -COOH͒, all with the same carbon chain length, were investigated. Along with dissolution and disk polish experiments, potential-pH diagrams were constructed for these three systems in the presence of H 2 O. The dissolution and polish rates are consistent with the known activity of carboxylic acids ͑with -COOH groups͒ at acidic conditions and that of amines ͑with -NH 2 groups͒ in an alkaline environment. The observed trends in the removal rates with all these slurries are explained using potential-pH diagrams, UV/visible spectra, and electrochemical experiments. When compared to glycine ͑H 2 N-CH 2 -COOH͒, ␤-alanine ͑H 2 N-CH 2 CH 2 -COOH͒ produced higher removal rates at acidic pH values and lower removal rates at alkaline pH values. Finally, succinic acid and ␤-alanine-based slurries were found to result in lower dissolution rates and higher polish rates compared to glycine-based slurries at pH 4.Chemical mechanical planarization ͑CMP͒ is widely used to planarize metal and dielectric films during integrated circuit fabrication. 1,2 Damascene process 3 is currently used in conjunction with CMP in the fabrication of multilevel copper ͑Cu͒ interconnects for advanced logic and memory devices. In this fabrication scheme, trenches are first patterned in a dielectric material at each level. After the barrier, seed, and copper fill are sequentially deposited in the dielectric trenches, 4 CMP is used to remove excess copper and create a planar surface for subsequent fabrication of additional levels of metallization.Cu CMP involves removal of material by the combined action of chemical and mechanical means to achieve planarization. Chemicals aid in material removal by modifying the surface film while abrasion between the particles in the slurry, pad, and the modified film facilitates mechanical removal. Material removal solely involving chemicals usually leads to uniform etching of both elevated and recessed regions and does not level the topography. The synergistic interplay between chemical and mechanical components in the slurry facilitates effective planarization. An important requirement of any successful copper CMP slurry is a high polishing rate leading to short copper overburden polishing times while minimizing dishing and erosion and other surface defects.With the introduction of low-k dielectric materials, integration of Cu/low-k dielectrics has become a serious challenge. These low-k dielectric films are porous, poorly adhere to Cu/Ta, are mechanically weak, and hence are prone to damage during CMP. 5 These problems can be mitigated by performing Cu and the barrier CMP at "low" pressures. 6,7 Because throughput can...

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