Nanomanufacturing of densely packed ultra-fine nanostructures by nano plastic forming and etching (NPFE)

In this paper, adhesion between a metallic mask and a substrate is studied for further improvement of nano plastic forming and etching (NPFE), a nanofabrication process developed recently by the authors, in terms of the minimum pitch that can be achieved by this process. Control parameters of sputter deposition process, i.e., mask thickness, gas pressure, and ion current were studied for their influence on the adhesion. Silicon wafer was used as the substrate, and gold (Au) was used as the mask. First, the influence of the mask thickness on the adhesion was investigated, and the proper thickness was determined. Then, the influence of gas pressure on the adhesion was investigated, and the optimum gas pressure, in order to achieve the minimum pitch, was determined. Finally, the influence of ion current on the adhesion was investigated, and the optimum ion current was determined. Array of 20-nm-wide trenches with a periodicity of 120 nm were fabricated on silicon wafer using the improved nano plastic forming and etching. This improvement demonstrates the capability of NPFE for fabricating densely packed nanostructures with ultra-fine feature size and extremely high resolution.