Copper CMP Formulation for 65 nm Device Planarization

To achieve 65 nm technology node requirements, CMP processes must provide improved control of selectivity, topography, wire cross section, and process robustness. Slurries and processes must also be compatible with fragile low k materials by providing low erosion and shear forces. We present data on a unique step 1 bulk Cu removal slurry with high selectivity, removal rates over 8000 A/min, and extremely low liner removal/erosion in high (90%) density structures. This is achieved through a combination of surface modified abrasives and alternative inhibitors which provide superior performance and reduced electrochemical activity compared to benzotriazole, a commonly used inhibitor. The step 1 slurry was used with a step 2 liner removal slurry that can be chemically tuned to adjust relative selectivities of Cu:Ta:oxide from the nominal ratio of 1:0.9:1.6, allowing its use with a variety of integration schemes. Results of CMP planarization experiments on 200 mm blanket and patterned single damascene test wafers are described, including electrical data which demonstrates low overpolish sensitivity.