Maskless patterning of borosilicate glass surface using nanoindentation-induced etch-hillock phenomena

A maskless patterning technique of borosilicate glass surface was studied by combining nanoindentation with HF isotropic etching. Effects of the process parameters (etch time, normal load, loading/unloading rate, and indentation hold-time under the maximum load) on the morphologies of the indented surfaces before and after etching were investigated. An indented borosilicate glass surface protruded rather higher than the initial height of the surface after etching in 50 wt% HF. The initial shape of the etch-hillock structure was the reversed image of the indent. As the etch time increased, the morphology of the etch-hillock structure gradually became round due to the isotropic etching property. The size of the etch-hillock structure was increased with increasing normal load. However, when the normal load was very small, the etch-hillock phenomena were not observed, because there was little plastic deformation, due to an indentation size effect. Conversely, the size of the etch-hillock structure did not vary despite the change of the loading/unloading rate or hold-time under the maximum load. With respect to deformation energies, the size of the etch-hillock structure was in proportion to the size of plastic deformation energy. By using this technique, sample characters were successfully written on the glass surface.