Electrically-assisted nanoimprint of block copolymers
Electrically-assisted nanoimprint of block copolymers
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DOI：
10.1116/1.5048204
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发表时间：
2019-01-01
影响因子：
1.4
通讯作者：
Zimmer, Klaus
中科院分区：
文献类型：
--
作者：
Mayer, Andre;Ai, Wenyang;Zimmer, Klaus
研究了垂直于衬底的电场对嵌段共聚物（BCP）相分离的引导作用，以获得可为后续刻蚀提供掩模的垂直结构。由于实际方面，衬底是裸Si，没有任何中性刷，并且处理时间限于1小时。本文采用聚苯乙烯-聚甲基丙烯酸甲酯嵌段层状材料。对于一个独特的引导的层状相，有序机制正交的电场引入的热纳米压印过程中与邮票的相互作用。印模的自然低表面能将导致沿线性腔的侧壁沿着形成层状结构。为了充分利用这两种排序机制，即印模侧壁和电场，压印过程以这样的方式进行，即在印模结构下方没有残留层，并且整个BCP积累在仅部分填充的空腔内。电辅助压印过程进行了分析研究，考虑到由于在腔中的局部电场，特别是在BCP的电容效应。此外，对实际实验条件进行了数值模拟，计算了BCP中的电矢量场。通过这种方式，获得了广泛的了解的情况下，这是选择电辅助热纳米压印的最佳实验条件的基础。此外，在热纳米压印过程中的电场的模糊性与部分填充的空腔解决。场应诱导垂直相分离，但由于不稳定性，它也可能诱导代表复制缺陷的毛细管桥。通过施加高达25 V/μ m的电场，可以确定在特定的实验条件下的垂直相分离的改进。然而，空腔内的引导作用以及由此产生的层流的长程有序性仍然有限。这可能是由于BCP中的场强太低;在本配置中，更高的场强被电气击穿所禁止。由AVS出版。
Guiding of the phase separation of a block copolymer (BCP) by an electric field perpendicular to the substrate is investigated in order to obtain vertical structures that can provide a mask for subsequent etching. Because of practical aspects, the substrate is bare Si without any neutral brush and the process time is limited to 1 h. A polystyrene-block polymethylmethacrylate lamellar material is employed in the study. For a unique guiding of the lamellar phase, an ordering mechanism orthogonal to the electric field is introduced by the interaction with the stamp in a thermal nanoimprint process. The naturally low surface energy of the stamp shall induce the formation of lamellae along the sidewalls of linear cavities. In order to fully utilize these two ordering mechanisms, the stamp sidewalls and the electric field, the imprint process is conducted in such a way that no residual layer remains below the stamp structures and the whole BCP is accumulated inside the cavities which are just partly filled. The electrically-assisted imprint process is studied analytically, considering the capacitive effects due to the local electric field in the cavity and in particular in the BCP. In addition, a numerical simulation is performed for the actual experimental conditions to compute the electric vector field in the BCP. In this way, an extensive understanding of the situation is gained which is the basis for choosing optimal experimental conditions for electrically-assisted thermal nanoimprint. Furthermore, the ambiguity of the electric field in a thermal nanoimprint process with partly filled cavities is addressed. The field shall induce vertical phase separation but, due to instabilities, it also may induce capillary bridges that represent replication defects. An improvement of the vertical phase separation by applying an electric field as high as 25 V/mu m could be identified under specific experimental conditions. However, the guiding effect within the cavities and thus the long-range order of the lamellae remained limited. This may be due to a field strength too low in the BCP; in the present configuration, higher field strengths are prohibited by an electrical breakthrough. Published by the AVS.