Lees Rhiannon, Cooke Michael D, Balocco Claudio, Gallant Andrew
Department of Engineering, Durham University, Durham, DH1 3LE, United Kingdom.
Sci Rep. 2019 Sep 6;9(1):12849. doi: 10.1038/s41598-019-48881-z.
In this paper, we use a finite difference time domain solver to simulate the near field optical properties of self-assembled microsphere arrays when exposed to an incoherent light source. Such arrays are typically used for microsphere lithography where each sphere acts as a ball lens, focusing ultraviolet light into an underlying photoresist layer. It is well known that arrays of circular features can be patterned using this technique. However, here, our simulations show that additional nanometer scale features can be introduced to the pattern by optimising the sphere dimensions and exposure conditions. These features are shown to arise from the contact points between the microspheres which produce paths for light leakage. For hexagonally close packed arrays, the six points of contact lead to star shapes in the photoresist. These star shapes have subfeature sizes comparable to the current achievable resolution of low-cost fabrication techniques.
在本文中，我们使用时域有限差分求解器来模拟自组装微球阵列在非相干光源照射下的近场光学特性。此类阵列通常用于微球光刻，其中每个微球充当球透镜，将紫外光聚焦到下面的光刻胶层中。众所周知，利用该技术可以对圆形特征阵列进行图案化。然而，在这里，我们的模拟表明，通过优化微球尺寸和曝光条件，可以在图案中引入额外的纳米级特征。这些特征是由微球之间的接触点产生的，这些接触点形成了光泄漏的路径。对于六角密排阵列，六个接触点会在光刻胶中形成星形。这些星形的子特征尺寸与当前低成本制造技术可实现的分辨率相当。
