Room-temperature electrically induced micro-structure patterning mechanism and technique

A non-contact electrically induced patterning technique was proposed for forming a periodic micro-structure on a polymer film at room temperature, based on the surface tension instability of liquid polymer film caused by thermal disturbance. An electro-mechanical model for the electrically induced polymer film rheology was established by using the Navier-Stokes equation and a linear stability theory to analyze the patterning dynamics, periodicity and growth factor of the micro-structure generated by the electrical field. An experiment of the electrically induced micro-patterning process at room temperature was carried out by using a low-viscosity UV curable polymer as the material for patterning. The experimental results have validated the feasibility of the electrically induced patterning with UV curable polymer at room temperature. The UV curable polymer film with a thickness of 0.8 μm was coated on the substrate of conductive doped silicon wafer and smooth conductive glass was used as flat mask. Direct current with voltage of 25 V was applied between the substrate and mask to carry out the experiment of electrically induced patterning, in which periodic pillars on large area were obtained, with the average centre to centre spacing of 37.6 μm and the average diameter of 24.8 μm. When the applied voltage was raised to 30 V, the average centre to centre spacing of periodic pillars was reduced to 30.8 μm and the average diameter of periodic pillars was reduced to 18.5 μm. Factors in the electrically induced process such as the induction time, template-to-film gap, and pattern size were analyzed in detail based on the theoretical model proposed. An approach to the process parameter optimization was suggested for achieving quick and high precision electrically induced patterning.