Enhanced dissolution of Al in a weakly corroding chlorine solution is observed as a result of the atomic-force-microscope tip-surface interaction. Under continuous scanning of a 3 X 3 mum area, a 100 nm thick Al coating can be stripped in less than 2 h, producing a cavity with sharp boundaries. The selected removal of material is due to the local increase in the dissolution rate of the Al film. We believe this is a direct consequence of the energy dissipation from frictional forces arising from scanning the tip over the surface. Many such cavities can be created on the same film, allowing therefore the creation of complex structure. This micromachining capability may prove to be extremely useful in the fabrication of high-resolution diffraction gratings and lithographic masks.