Focused laser-induced marangoni dewetting for patterning polymer thin films

ABSTRACT Highly‐localized focused laser spike (FLaSk) heating of polymer thin films is a resist‐ and developer‐free alternative to two‐dimensional (2D) laser direct write for creating patterns on the single micron or, by exploiting overlap effects, submicron scale. The massive temporal and spatial thermal gradients and resulting thermal Marangoni stresses generated by FLaSk are an effective means for the directed dewetting and patterning of such films. Here, the general applicability of this technique to glassy amorphous polymer thin film systems is investigated through systematic investigation of film thickness, glass transition temperature, and polymer mobility. The results reveal that the important parameters are the film thickness (coupled to the optical heating effects through anti‐reflection coating effects) and the high‐temperature polymer melt mobility, allowing for generation of single features with linewidths of down to ∼1 μm. Further, the introduction of spatial mobility variations by using polymer brushes, bilayers, and microphase separated block copolymers leads to additional profile manipulation effects (i.e. spontaneous 2D pattern generation and flattened top profiles). © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 225–236 An investigation of the effect of various experimental parameters reveals that the focus laser spike (FLaSk)‐induced thermocapillary dewetting of polymer thin films patterns lines whose profile shapes depend mainly on the high temperature melt mobility (related to molecular weight) and the film thickness (related to antireflection effects) of the polymer. This allows for generalized processing of multiple materials systems. In addition, bilayer mobility and use of solvent swelling lead to other profile variations, namely segmented and “flat‐topped” line patterns.