真空电子器件的频率正向太赫兹频段发展, 折叠波导慢波结构是行波管的核心部件, 由于真空器件的尺寸与波长具有共渡性, 频率越高, 互作用结构的尺度越小, 加工误差的要求越严格。传统的加工方法很难实现如此微小尺寸的结构, UV-LIGA技术对于制造这种微型结构是一种很有前途的方法。用UV-LIGA方法制备真空器件的慢波结构, 涉及到两个主要的问题: 一是SU8厚胶匀胶过程中如何确保其厚度及其一致性;二是横向贯穿折叠波导中心的电子注通道如何成型。以220 GHz折叠波导为研究对象, 针对上述两个问题开展了相关的工艺试验, 使用特制的PDMS模具, 采用重力匀胶法, 实现了大厚度SU8胶匀胶, 表面平整, 高度一致。在SU8光刻胶中通过专用夹具, 嵌入透明有机丝, 形成细长电子注通道。而后, 采用脉冲电铸电源, 在硫酸铜电铸液中电铸, 获得了表面平整的无氧铜微结构。

Folded waveguide slow-wave structure as a traveling wave tube’s main component is becoming smaller and smaller with vacuum electron devices operating frequency rises towards THz. And the fabrication tolerances are becoming increasingly critical. Traditional methods don’t adapt to these micro-scale ranges. UV-LIGA is an attractive technique for fabricating this structure. This paper focuses on microfabrication techniques using SU8 photoresists to create this circuit at 220 GHz and a special mould made by PDMS and embedded polymer monofilament to assure the thickness and shape of the beam tunnel. By optimizing the process parameters, using gravity-assisted deposition technique, SU8 mold with coincident thickness and smooth surface is realized. After electroforming in a bath composed with sulfuric acid and copper sulfate and drawing out polymer monofilament, the microstructure is fabricated.