Nanometer-Scale Patterning of Polystyrene Resists in Low-Voltage Electron Beam Lithography

We studied nanometer-scale patterning using a polystyrene negative resist in electron beam lithography. We found that the use of a low-molecular-weight polystyrene enables 10-nm-level patterning at low-acceleration voltage. We also found that the spot dose of such ultrasmall patterns formed at a 5 kV acceleration voltage was one-tenth of that formed at 50 kV. Low-voltage electron beam lithography is a suitable technique for organic resist nanopatterning. The Charlesby theory can still be applied to nanodot formation, and we can therefore estimate the dot sensitivity for various polystyrene molecular weights. We suppose that an exposure model is based on polymer aggregation to explain the formation of a 10-nm-level pattern with a height of 40 nm can be formed by using a small molecule, not a large one.