Improving the lifespan of the cantilever during electron assisted AFM lithography

Abstract

Electron assisted atomic force microscope (AFM) lithography is a relatively simple and flexible lithography method with a resolution of below 100nm. An electron beam (EB) resist is patterned by scanning a fine needle (cantilever) on the resist surface while applying a voltage. However, one of the problems of electron assisted AFM lithography is wear of the cantilever apex, which causes changes in the line width and impedes long-distance patterning. To overcome this problem, we examined ways of improving the lifespan of the cantilever during electron assisted AFM lithography by coating the EB resist with a fluorinated silane coupling agent (Optool DSX) as a low-friction layer and by coating the cantilever apex with platinum (Pt) to protect the cantilever. Through these two means, we achieved long-distance (more than eight times) patterning without any significant change in line width (less than a few nanometers) using the electron assisted AFM lithography system (MPS-1000, Sumitomo Precision Products Co. Ltd.). The delineated distance was 2000@mm (=2mm) and the line width remained constant at 60nm from start to finish. It took 34min to complete the patterning.