Institute for Microelectronics and Microsystems, National Research Council (CNR-IMM), Via del Fosso del Cavaliere 100, 00133 Rome, Italy.
Department of Electronic Engineering, University of Rome "Tor Vergata", Via del Politecnico 1, 00133 Rome, Italy.
Sensors (Basel). 2023 Mar 22;23(6):3360. doi: 10.3390/s23063360.
This work details an effective dynamic chemical etching technique to fabricate ultra-sharp tips for Scanning Near-Field Microwave Microscopy (SNMM). The protruded cylindrical part of the inner conductor in a commercial SMA (Sub Miniature A) coaxial connector is tapered by a dynamic chemical etching process using ferric chloride. The technique is optimized to fabricate ultra-sharp probe tips with controllable shapes and tapered down to have a radius of tip apex around ∼1 μm. The detailed optimization facilitated the fabrication of reproducible high-quality probes suitable for non-contact SNMM operation. A simple analytical model is also presented to better describe the dynamics of the tip formation. The near-field characteristics of the tips are evaluated by finite element method (FEM) based electromagnetic simulations and the performance of the probes has been validated experimentally by means of imaging a metal-dielectric sample using the in-house scanning near-field microwave microscopy system.
这项工作详细介绍了一种有效的动态化学蚀刻技术，用于制造扫描近场微波显微镜（SNMM）的超锐利探针。通过使用氯化铁的动态化学蚀刻工艺，对商业 SMA（Sub Miniature A）同轴连接器中的内导体的突出圆柱形部分进行了锥形处理。该技术经过优化，可制造出具有可控形状和逐渐变细至尖端半径约为 1μm 的超锐利探针。详细的优化促进了可重复使用的高质量探针的制造，适用于非接触式 SNMM 操作。还提出了一个简单的分析模型，以更好地描述尖端形成的动力学。通过基于有限元方法（FEM）的电磁模拟评估了尖端的近场特性，并通过使用内部扫描近场微波显微镜系统对金属-介质样品进行成像来实验验证了探针的性能。
