Study of the kinetics of step and flash imprint lithography photopolymerization



Step and Flash Imprint Lithography (SFIL) is a promising high-resolution, yet low-cost patterning technique that uses a UV induced photopolymerization to replicate features on a patterned template. The SFIL process utilizes an acrylate-based free radical polymerization, which is inhibited by oxygen. A semiempirical kinetic model is presented that demonstrates the effects of oxygen on SFIL. On the basis of kinetic measurements, dissolved oxygen causes an inhibition period at the onset of exposure that extends the required exposure time. Oxygen inhibition also results in a thin perimeter of under-cured material surrounding the template due to oxygen diffusion from the ambient during polymerization. The model allows us to study the impact of oxygen on SFIL as a function of various formulation and exposure variables. Methods of limiting the impact of oxygen are presented, such as alternative chemistries and inerting techniques. © 2005 American Institute of Chemical Engineers AIChE J, 2005