Liu Min, Yang Qian, Zhang Anxue, Guo Cheng, Chen Juan
School of Information and Communications Engineering, Xi'an Jiaotong University, Xi'an 710049, China.
Sensors (Basel). 2022 Jul 27;22(15):5604. doi: 10.3390/s22155604.
This paper investigates the fabrication accuracy of the W-band SU-8 photoresist micromachined 4th order waveguide bandpass filters (BPF). The designed filter based on cylindrical resonators is excited in TM mode. It is ideally suitable for the layered SU-8 micromachining process as the height of the resonator is much smaller than one wavelength, the electromagnetic fields remain unchanged in the thickness direction. The filter is composed of three silver-coated SU-8 layers based on a double-layer overlay process. Excellent manufacturing tolerances can be controlled within 4 μm in the thickness direction, around 10 μm in double-layer stacking accuracy, and an average of 1° in vertical angle deviation. Various challenges encountered in the SU-8 process are investigated while corresponding general solutions are proposed for machining high-precision devices. The measured results show a return loss of 12.4 dB and a minimum insertion loss of 0.8 dB, which are in agreement with the simulated one. Stress and deformation analysis are also conducted to confirm the maximum pressure that the filter can withstand and maintain good transmission performance.
本文研究了W波段SU-8光刻胶微加工四阶波导带通滤波器（BPF）的制造精度。基于圆柱形谐振器设计的滤波器以TM模式激励。由于谐振器的高度远小于一个波长，电磁场在厚度方向上保持不变，因此它非常适合分层SU-8微加工工艺。该滤波器基于双层叠加工艺由三层镀银的SU-8层组成。在厚度方向上，制造公差可控制在4μm以内，双层堆叠精度约为10μm，垂直角度偏差平均为1°。研究了SU-8工艺中遇到的各种挑战，同时针对加工高精度器件提出了相应的通用解决方案。测量结果显示回波损耗为12.4dB，最小插入损耗为0.8dB，与模拟结果一致。还进行了应力和变形分析，以确定滤波器能够承受并保持良好传输性能的最大压力。
