Jiang Youwei, Luo Bingqing, Cheng Xing
SUSTech Academy for Advanced Interdisciplinary Studies, Southern University of Science and Technology, Shenzhen 518055, China.
Shenzhen Key Laboratory for Nanoimprint Technology, Southern University of Science and Technology, Shenzhen 518055, China.
Materials (Basel). 2019 Feb 12;12(3):545. doi: 10.3390/ma12030545.
Thermoplastic polymer micro- and nanostructures suffer pattern decay when heated to a temperature close to or above the polymer's glass transition temperature. In this work, we report enhanced thermal stability of polycarbonate nanostructures at temperatures well above their glass transition temperatures. Based on this observation, we develop a unique technique for high-resolution polymer patterning by polymer reflows. This technique is characterized as the precise control of polymer reflows regardless of the annealing time, which avoids the time-domain nonlinear reflow of the polymer melt. We also implement thermal nanoimprinting in a step-and-repeat fashion, which dramatically increases the throughput of the thermal nanoimprint. The enhanced pattern stability against thermal reflow also allows for multiple imprinting at the same location to generate complex resist patterns from a simple mold structure. Since modern lithography often uses thin resist films (sub-100 nm) due to the restraint from the pattern aspect ratio, the unusual annealing behavior of thin polymer films is highly relevant in sub-100 nm lithographic processing.
热塑性聚合物的微纳结构在加热到接近或高于聚合物玻璃化转变温度时会出现图案衰减。在这项工作中，我们报告了聚碳酸酯纳米结构在远高于其玻璃化转变温度时具有增强的热稳定性。基于这一观察结果，我们开发了一种通过聚合物回流进行高分辨率聚合物图案化的独特技术。该技术的特点是无论退火时间如何，都能精确控制聚合物回流，避免了聚合物熔体的时域非线性回流。我们还以步进重复的方式实现了热纳米压印，这显著提高了热纳米压印的产量。增强的抗热回流图案稳定性还允许在同一位置进行多次压印，以从简单的模具结构生成复杂的抗蚀剂图案。由于现代光刻技术由于图案纵横比的限制经常使用薄抗蚀剂膜（低于100纳米），因此薄聚合物膜不寻常的退火行为在低于100纳米的光刻工艺中具有高度相关性。
