超高深宽比的太赫兹全金属光栅微加工关键问题研究

As an emerging field of terahertz vacuum electron devices, microfabrication techniques have been concerned gradually by researchers home and abroad. Regarded as the most promising method to microfabricate terahertz metal gratings, UV-LIGA has been investigated by excessive and repeating experiments to achieve the optimum process conditions for specific devices. The simple experimental methodology is not universal and costly. Based on the microfabrication of metal grating with the depth exceeding 700 micrometers and aspect ration >10:1, the project will aim at the effect of internal stress and thermal swelling existed in SU-8 and focus on the mechanism of the metal-ion's motion in the electrical field and flow field. By means of integration of theoretical analysis, simulation and experimental optimization, a prediction model of SU-8 layer's internal stress will be established, as well as a velocity model of SU-8-layer's thermal swelling. The distribution of electrical field and flow field will be optimized. Then the key technical problems will be solved by quantitative results and conclusions deduced from the above models. Finally, combined with the estimation of high-frequency performance, a complete microfabrication system will be build up. This is a basic research for application, which will promote the develop and future practical application of vacuum electron devices.

微加工技术作为太赫兹真空电子器件研究的一个新兴方向，逐渐受到国内外研究者的关注。作为超高深宽比的太赫兹金属光栅最具潜力的微加工方法，UV-LIGA工艺目前的研究采用大量重复性的实验以获得特定器件的最佳工艺条件，实验成本大，且不具有普适性。本项目以厚度不小于700微米、深宽比超过10:1的全金属光栅的UV-LIGA工艺为载体，拟针对UV-LIGA工艺中SU-8胶皮的内应力、热溶胀效应和金属离子在电场和流场中的运动机理，采用理论分析、模拟仿真与实验相结合的方法，建立内应力预测模型和溶胀性的速率模型，优化电场和流场分布。结合上述模型和最优电场分布的定量分析，加工出目标光栅。最后结合工艺误差对太赫兹光栅高频性能的影响的分析，建立微加工完善的工艺理论体系和工艺评价体系。这项课题属于应用基础研究，对太赫兹真空电子器件的发展及实用化有重要的推动作用。

太赫兹金属器件的成功制作是目前制约太赫兹真空电子器件实用化的瓶颈。本项目以高深宽比的太赫兹全金属光栅为加工目标，采用模拟仿真和工艺实验相结合的研究手段，通过研究工艺过程中的相关作用机理，比如光刻胶的内应力和溶胀效应，以及金属离子在电场和流场中的运动规律和影响因素，解决了工艺过程中的关键性问题。在此基础上，形成了固化的工艺流程，成功加工了质量良好、有着光滑表面的全金属太赫兹光栅。本项目研究属于基础应用研究，对太赫兹真空电子器件的发展和实用化会起到一定的推动作用。