Kim Ju Hyeon, Choi Jae-Hoon, Sim Jae Young, Jeong Woong Chan, Yang Seung-Man, Kim Shin-Hyun
Department of Chemical and Biomolecular Engineering, KAIST , Daejeon, South Korea.
Langmuir. 2014 May 20;30(19):5404-11. doi: 10.1021/la5007692. Epub 2014 May 8.
Monodisperse emulsion droplets with a high volume fraction form crystalline phases that can potentially serve as adjustable photomasks in photolithography. Such photomasks were prepared using a microfluidic device in which a flow-focusing junction, side channels, and a reservoir were connected in series. Transparent oil droplets were generated in a dye-containing continuous water phase at the flow-focusing junction. The droplets were then concentrated through the selective removal of the continuous phase using the side channels. This process led to the formation of a regular array of droplets in the reservoir with a configuration that depended on the relative height of the reservoir to the droplet diameter. The configurations could be selected among a single-layered hexagonal array, a bilayered square array, and a bilayered hexagonal array. The droplet arrays were used as a photomask to create hexagonal or square arrays of microdots. The transmittance profile of the ultraviolet (UV) light from each droplet was parabolic, which enabled the dot size to be tuned by controlling the UV irradiation time. This mask effect is otherwise difficult to achieve using conventional photomasks. The dot size and array periodicity could be adjusted by the in-situ control of the droplet size at the flow-focusing droplet maker. The combination of droplet size adjustments and the UV irradiation time provided independent control over the dot size and array periodicity to enable the preparation of a series of hexagonal microarrays with a wide spectrum of array parameters using a single microfluidic device.
具有高体积分数的单分散乳液液滴形成的晶相可潜在地用作光刻中的可调光掩模。此类光掩模是使用微流控装置制备的，该装置中流动聚焦结、侧通道和储液器串联连接。在流动聚焦结处，在含染料的连续水相中产生透明油滴。然后使用侧通道通过选择性去除连续相来浓缩液滴。此过程导致在储液器中形成规则排列的液滴阵列，其结构取决于储液器相对于液滴直径的相对高度。这些结构可以在单层六边形阵列、双层正方形阵列和双层六边形阵列中选择。液滴阵列用作光掩模以创建六边形或正方形微点阵列。来自每个液滴的紫外光的透射率分布是抛物线形的，这使得可以通过控制紫外线照射时间来调整点的大小。使用传统光掩模很难实现这种掩模效果。点的大小和阵列周期性可以通过在流动聚焦液滴制造器处原位控制液滴大小来调整。液滴大小调整和紫外线照射时间的组合提供了对点大小和阵列周期性的独立控制，从而能够使用单个微流控装置制备一系列具有广泛阵列参数的六边形微阵列。
