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Controlled patterning of polymer films using an AFM tip as a nano-hammer

A force-modulated atomic force microscope (AFM) was used to produce controlled two-dimensional nano-structure arrays in polymer films. Unmodulated AFM methods have not achieved the registry control necessary to generate multi-dimensional structures. Registry control was achieved by generating optimally modulated stress waves using a scanning AFM cantilever tip as a nano-hammer. Ordered nano-dots in selected two-dimensional lattice structures were constructed by reshaping the surface of polystyrene thin films using the force-modulated AFM tip. Selecting the wavelength and orientation of the stress distribution in polymer films enabled control of the periodicity and symmetry of nano-arrays. The formation and growth of the nano-structures are attributed to the stress-induced reconstruction in the thin polymer films. Surface reconstruction models based on the stress-induced instability near polymer surfaces may provide further insight into structures induced in polymers by a scanning tip.