Single-material-based multilayered nanostructures fabrication via reverse thermal nanoimprinting

We demonstrated a multilayered, residual-free nanostructure by stacking a one-dimensional grating in an orthogonal arrangement via reverse thermal nanoimprinting and reactive ion etching technique using a single material (PMMA). We found that a good pattern transfer with minimal residual layers was mainly determined by four important factors: the concentration of PMMA in toluene solution, the type of fluorosilane used on the mold surface, and the temperature and pressure used in reverse nanoimprinting. The first layer was reverse-nanoimprinted at the temperature of 150 °C, while the subsequent layers were achieved at the onset temperature of the glass transition of PMMA. Experimental results showed that the compression of the bottom layer was inevitable due to a change in mechanical property of the PMMA after repeated reverse nanoimprinting process.