Investigation on several crucial factors influencing the hot embossing lithography with TiN mold

During hot embosssing process, direct physical contact of the mold and substrate occurs, and during the process, pressure, temperature and time are important for the imprinting quality. Completely filling up the mold is crucial to the pattern replication. In order to apply proper parameters to hot embossing process, it is necessary to well understand the flux mechanism of the polymer. Numerical simulation using Ansys software was carried out. First, hyperelastic model was set up to study the relationship between polymer deformation and pressure. The results indicate that inceasing the pressure only can not improve the hot embossing performance obviously. Second, the polymer stress distribution in cooling down step reveals that stress convergence exsits, which means that pressure removal above the transition temperature of the polymer glass could avoid imprint defects. Finally, influence of different thermal expansion coefficient between mold and polymer was investigated. The results indicate strain convergence was produced in cooling down by thermal expansion coefficient difference of mold and photoresist. Hence it is better to select material of the mold, which has similar expansion coefficient with that of the photoresist.