Study on the Effects of the Machining Parameters on the Fabrication of Nanoscale Pits Using the Dynamic Plowing Lithography Approach

The dynamic plowing lithography approach is employed to fabricate nanoscale pits on polymer thin films with a high throughput based on a commercial atomic force microscope (AFM) in this study. The effects of the drive amplitude ratio and the molecular weight on the fabrication of the nanoscale pits are investigated first on the poly(methyl methacrylate) (PMMA) thin films. In particular, the critical value for the transformation of the grooves to the pits and the ratio of the experimental distance between the adjacent two pits and the calculation distance between adjacent penetrations of the AFM probe are assessed. Results show that the drive amplitude ratio and the molecular weight have little influence on the machining outcomes. The critical value is evaluated as around 100 μm/s, and the ratio described above is varied in the range of 60-80 times. As a contrast, the polycarbonate and polystyrene thin films are selected. The corresponding critical value can be evaluated as 20-30 μm/s, which is much smaller than that obtained on the PMMA thin film. The possible reason can be explained as the change of the surface elastic modulus. While the ratio of the pits distance is almost in the same range with the results given for the PMMA thin film. Furthermore, a lower drive frequency is also chosen to scratch on the polymer surface. However, only nanogrooves can be created even the scratching velocity reaches to 1000 μm/s. In this case, the machined depth of the nanogrooves is varied with the scratching velocity in the whole range of scratching velocity. Finally, 8-bit ASCII code could be obtained with the arrays of the pits with eight columns for the meaning of figures or symbols.