AFM tip-based fabrication of silicon nanostructures with reduced subsurface amorphous layers

Atomic force microscopy (AFM) tip-based nanofabrication is a feasible method to create nanofeatures on a variety of materials. Surface/subsurface integrity is important for qualifying surface performances. However, while machining on crystalline materials, subsurface amorphous layers are inevitably produced because of the large stress in the contact area between the sharp tip and the workpiece surface, which would reduce the mechanical performance of the surface. In this work, multi-pass reciprocating cutting (MPRC) was implemented to reduce the subsurface amorphous layer (SAL) of a single crystal silicon. The mechanism was studied by experiments and molecular dynamic simulation. Results showed the thickness of the amorphous layer can be greatly decreased to a low value and the tip wear can be reduced as well by the MPRC method. On this basis, by optimizing the machining parameters of the MPRC method, nanogrooves with varied depths but few subsurface amorphous phases were successfully fabricated.