Investigation of resist filling behavior in microimprint lithography by computational fluid dynamics simulation and defocusing digital particle image velocimetry

Abstract

Resist filling behavior is crucial to the quality of final imprinted patterns in microimprint lithography (MIL). This article investigates the velocity field of the resist in microimprint lithography through numerical simulations and visualization experiments. To achieve the microscale velocity field of resist, a numerical model based on the computational fluid dynamics was built to predict the resist filling behavior, and the surface tension and contact angle were considered in this model. Meanwhile, a 3-D defocusing digital particle image velocimetry (DDPIV) was established. The spatial coordinates of the fluorescent tracer particles were derived from their DDPIV images. Time-resolved 3-D particle field inside the resist was obtained with the spatial coordinates. Particle tracking velocimetry was utilized to derive the velocity field from the particles' spatial position in the imprinting process. The investigation of the velocity field, including the horizontal and vertical velocity history, was carried out to directly describe the filling mode of the resist and hence determining the resist filling mechanism. The results of the visualization experiments and the numerical simulations were compared to obtain an in-depth understanding of the resist flow in MIL.