Scratch lithography of 10 nm silicon structures

A new lithography method, scratch lithography, is proposed for fabrication of silicon nanostructures. When a poly(methylmethacrylate) (PMMA) layer coated on a Si substrate is: scratched by a needle, some of the PMMA molecules adhere to the substrate and cannot be removed by rinsing in acetone. The individual PMMA molecules thus fixed to the surface can be used as etch masks for electron cyclotron resonance microwave plasma etching (ECR etching) with SF6 at a low temperature (-130 degrees C), which leads to formation of Si pillars of 10 nm diameter with a high aspect ratio (similar to 10). A 10-nm-wide line was also formed unintentionally, probably owing to the microroughness of the tip, suggesting that it may be possible to fabricate well-controlled nanostructures if the scratching tip is reduced to nanometer dimensions.