外力引导式化学刻蚀加工新方法制造皮升级微流体泵的基础研究

In post Moore Law era, the sustaining development of IC relies on the upgrade of manufacturing technology and equipment more and more heavily, therefore, fundamental research for new manufacturing method is eagerly needed. Inkjet printing is one of the most promising manufacturing methods. In order to maintain the nano-scale manufacturing precision, the greatest bottleneck that how to form tiny droplet of liquid and control their movement is urgently needed to break through. In this proposal, a novel method for picolilter droplet formation based on inverted tapered nano-pillars is proposed. The driving force arising from shape gradient (Laplace force) forms tiny droplets and propels them upward region with larger curvature radius. This can overcome disadvantages of droplets formation methods by the small nozzle. And a novel method for manufacturing such nano-pillars liquid pump based on external force facilitated chemical etching is also firstly proposed. By controlling the movement of metal crystals, arbitrary micro/nano features can be anisotropically formed in bulk materials by this method, such as inverted tapered nano-pillars arrays. By studying and unclosing the momentum transport mechanism of picolilter microfluidic pump based on inverted tapered nano-pillars, manufacturing mechanism for chemical etching facilitated by external forces, and the coupling mechanism of nanoparticles and microfluidic under external load in limited space, the theoretical system for such nano-pillars microfluidic pump from design to manufacturing will be preliminary built, and the critical problem for forming and control tiny droplet will be solved. The success of this project will provide insights for improving micro/nano manufacturing and inkjet printing technology, and has important theoretical significance and application value.

后摩尔时代，制造工艺与装备的升级是IC产业转型升级的重要支撑，亟需开展制造新方法的基础研究。微纳喷射打印是一种极具前景的制造方式，但迫切需要突破“皮升级体积、微纳尺寸液滴形成并控制其运动”这一瓶颈环节，以保证制造中所需的纳米精度。为此，本项目提出了基于倒圆台纳米柱的微流体泵，靠结构曲率差异产生的驱动力在纳米柱表面形成和泵送皮升级微液滴，突破传统方法中形成的液滴体积过大的难题。同时提出了外力引导式化学刻蚀加工微流体泵的新方法，在块体材料内部定向加工出所需的倒圆台纳米柱阵列，克服传统方法难以加工下端面小上端面大这类特殊微纳结构的难题。本项目通过研究微液滴的形成及高效泵送机制、材料定向加工机理、外力作用下受限空间内纳米粒子与微流体耦合作用机制等关键科学问题，初步建立皮升级纳米柱微流体泵从设计到制造的理论研究体系，解决IC微纳喷射打印制造中皮升级微液滴生成的难题，具有重要的理论意义和应用价值。

微纳喷射打印是一种极具前景的制造方式，但迫切需要突破“微纳尺寸液滴形成并控制其运动”这一瓶颈环节，以保证制造中所需的精度。为此，本项目建立了微液滴克服重力自发性传输的数值理论模型，并设计出了能够实现自发性传输的倒锥形微柱流体泵，给出了各个参数的阈值（锥角小于10°；倒倒圆台微柱底部直径小于80μm；液滴与微结构表面接触角小于54.5°）；开发了实验加工平台，搭建了微液滴自发传输动态过程的实验观测平台，通过实验证明所加工的微结构能够克服重力自发性传输微液滴，最快传输速度达到0.06m/s。针对当前自发性液滴输送距离受限的难题，受接力赛跑的启发，提出了一种多节首尾相连的楼梯状锥形微结构来克服该问题，并揭示了能够实现液滴自发性长距离传输的阈值条件。发明了加工此类复杂微纳结构的交替性刻蚀-保护的加工新方法，通过实验证实了通过楼梯状锥形微流体泵可以实现平均速度为0.139 m/s、最大加速度为5g、距离超过8mm的自发性传输。通过优化实验设计，获得了较优的工艺参数为：倾斜角0°-25°、接触角50°、化学表面修饰时间为5 min。此外，基于楼梯状锥形微流体泵，设计了水雾收集器件，相比传统的单节锥形微流体泵，其工作效率可以提高53.5%。围绕复杂微纳结构加工方面，还发明了两种形状可控弯折纳米微结构的外力引导式刻蚀加工新方法，开发了相应的刻蚀加工装备，加工的纳米柱深径比超过200，为已知的最高世界纪录；并首次实现了碳化硅等第三代半导体纳米孔和纳米柱的湿法刻蚀加工；被Wiley旗下的Materials Views中国、搜狐网、网易等多家媒体广泛报道。.综上，初步建立了自发性定向传输的微流体泵从设计到加工的理论研究体系，揭示了半导体微纳结构选择性定向加工机理与机制，加工出各类微纳结构，相关技术有望在半导体加工、微流控器件等领域应用。发表SCI论文9篇，其中影响因子超过10的4篇，EI论文3篇，授权发明专利30件(3件美国)，形成了国际研究优势。毕业博士生2人、硕士生4名。项目负责人入选香江学者计划，获省部级奖3项。

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