Predicting the fluid behavior during the dispensing process for step-and-flash imprint lithography

In this article, the polymer dispense process in the step-and-flash imprint lithography is investigated with computational fluid dynamics (CFD) models. The dispense process is a function of the fluid properties and the system parameters such as the geometry and the details of the actuation motion. Physical arguments show that this functional dependence can be reduced to two dimensionless numbers: the Weber number which represents the ratio of inertia to surface tension forces, and the capillary number which represents the ratio of viscous to surface tension forces. A parametric study showed that there is a clear optimal regime for the dispensing process in which a single, clearly-defined drop forms. The CFD model was verified experimentally by comparing the predicted fluid dispense behavior with photographs of a dispense process.