Direct Three Dimensional Nanoscale Thermal Lithography at High Speeds Using Heated Atomic Force Microscope Cantilevers

This paper reports a novel lithography method that utilizes local nanoscale thermal decomposition of polymer films using heated atomic force microscope cantilever probe tips. Cross-linkable polymers, for example based on poly(hydroxystyrene) (also referred to as PHOST), are used as the writing material in these methods. The experimental results show that the cross-linked polymer can prevent the thermal flowing induced by melting of the polymer, and very fine feature can be achieved. 100 nm lines have been successfully written using a heated cantilever probe in a crosslinked PHOST film. 60 um/sec writing speeds have also been achieved using this technology. The amount of material decomposed by the heated tip can be very well controlled by modulating both the cantilever probe temperature and writing speed. This ability to modulate the removal rate of material from the film makes it possible to directly pattern 3-D structures into a polymer film using such heated AFM cantilever tips.