Department of Chemical Engineering and DST Unit on Nanoscience, Indian Institute of Technology Kanpur, Kanpur, 208016, India.
Small. 2011 Mar 21;7(6):758-65. doi: 10.1002/smll.201001939. Epub 2011 Feb 2.
An ultrafast, parallel, and beyond-the-master micropatterning technique for ultrathin (30-400 nm) nonabsorbing polymer films by diffraction of laser light through a 2D periodic aperture is reported. The redistribution of laser energy absorbed by the substrate causes self-organization of polymer thin films in the form of wrinklelike surface relief structures caused by localized melting and freezing of the thin film. Unlike conventional laser ablation and laser writing processes, low laser fluence is employed to only passively swell the polymer as a pre-ablative process without loss of material, and without absorption/reaction with incident radiation. Self-organization in the thin polymer film, aided by the diffraction pattern, produces microstructures made up of thin raised lines. These regular microstructures have far more complex morphologies than the mask geometry and very narrow line widths that can be an order of magnitude smaller than the openings in the mask. The microstructure morphology is easily modulated by changing the film thickness, aperture size, and geometry, and by changing the diffraction pattern.
报道了一种超快、并行、超越主模板的微纳加工技术，通过二维周期性孔径对激光进行衍射，可在超薄（30-400nm）非吸收聚合物薄膜上形成图案。激光能量在衬底上的再分配导致聚合物薄膜自组织成波纹状的表面浮雕结构，这是由薄膜的局部熔化和冻结引起的。与传统的激光烧蚀和激光写入工艺不同，低激光强度仅用于在不损失材料的情况下作为预烧蚀过程被动地使聚合物溶胀，并且不与入射辐射发生吸收/反应。在衍射图案的辅助下，薄聚合物薄膜中的自组织产生了由薄凸起线组成的微结构。这些规则的微结构具有比掩模几何形状复杂得多的形态，并且线宽非常窄，比掩模中的开口小一个数量级。通过改变薄膜厚度、孔径大小和几何形状以及改变衍射图案，很容易调节微结构的形态。
