Single Asperity Atomic Force Microscope Studies of the CMP of Silicate Glasses

The Atomic Force Microscope (AFM) allows one to examine the effects of applying highly localized stress to a surface. In the presence of solutions, tribochemical wear can be investigated. We present results of fundamental studies of the simultaneous application of chemical agents and mechanical stress involving a model single asperity and a solid surface. We show the consequences of combining highly localized mechanical stress (due to contact with the AFM tip) and exposure to aqueous solutions of known pH. The experiment simulates many features of a single particle-substrate-slurry interaction in CMP. We show that linear scans and rastered scans display significantly different material removal rates. Quantitative models are presented to explain the observed nanometer-scale surface modifications. This work complements recent observations of tip-induced wear and growth in a number of inorganic surfaces in aqueous solution.