(435a) Models for Scale Up of UV Roll-to-Roll Imprint Lithography

Roll-to-roll nanoimprint lithography (R2RNIL) is a process based on batch nanoimprint lithography to replicate nano- and micro-scale patterns from the surface of a patterned mold wrapped on a roller to a large area, flexible or rigid substrate.  One of the most appealing features of the R2RNIL is the ability to manufacture continuous rolls of patterned substrate. The throughput of the process and the quality of pattern replication is governed by the UV-exposure time, the peeling mechanism, and the forces on the substrate and the roller. However, there is a lack of understanding of the quantitative effects of the associated process parameters and material properties on the dynamics of the imprinting process.

Here we model the process and identify key parameters for scale up from an analysis of the fluid, curing and peeling dynamics. This work focuses on the roll-to-roll nanoimprint lithography process with UV curing and inkjet dispensing on a rigid substrate. The process includes merging of droplets of imprint material, curing of the imprint material from a viscous liquid to elastic solid resist, and pattern replication and detachment of the resist from template.  The time and distances on the web or rigid substrate over which these processes occur are determined as function of the physical properties of the uncured liquid, the cured solid and the roller configuration. The upper convected Maxwell equation is used to model the curing viscoelastic liquid and to calculate the force on the substrate and the torque on the roller. The available exposure time is found to be the rate limiting parameter and is a function of the radius of the roller, the minimum gap between the roller and web, and the velocity of the web. It is found that the residual layer thickness of the resist must be larger than the gap between the roller and the substrate to ensure complete feature filling and optimal pattern replication.  For lower residual layer thickness, the droplets may not merge to form a continuous film for pattern transfer. The results of this work help determine the optimal operating conditions for this roll-to-roll nanoimprint lithography process.