Evaluation of Viscosity Characteristics of UV Nanoimprint Resin in a Thin Film

Abstract

For UV nanoimprint process, viscosity of a UV-curable resin is one of the key parameters to determine the process speed of fluid filling in recesses of a mold. In such a process, a UV-curable resin is usually assumed as a Newtonian fluid with a viscosity same as the bulk value. However, the true characteristics of UV-curable resin in UV nanoimprint condition are not known. We therefore constructed a viscosity measurement system for a thin liquid film on a wafer. A droplet of liquid (measuring object) on a mold was contacted to a wafer and the mold is forced to move reciprocally after the liquid was entirely spread between the mold and the wafer. We obtained time evolution curves of force and position and could convert the curves into a relation between force and velocity. The performance of the viscosity measurement system was evaluated using polydimethylsiloxane as a standard viscous fluid. Then, we measured viscosity characteristics of a UV-curable resin PAK-01 in a thin film using the viscosity measurement system. The viscosity measurement system showed that the PAK-01 film with a thickness of 1 μm is Newtonian fluid with a viscosity 30% less than the bulk value.