Step-and-repeat process for thermal nanoimprint lithography.

We present a step-and-repeat process for thermal nanoimprint lithography. For the selective heating and imprinting, a spin-coated polystyrene layer is exposed to infra-red rays from a halogen lamp (intensity approximately 500 W) with a metal-covered glass while pressed with a transparent polymer mold (Young's modulus approximately 300 MPa) under a pressure of approximately 4 bar for 60-120 s. During imprinting, the non-irradiated region is protected by a metal screen and a heat sink consisting of a copper block at the bottom which prevents the pattern collapse by lateral heat conduction from the irradiated region.