3-dimensional micromachining of PTFE using synchrotron radiation direct photo-etching

In order to fabricate highly functional microdevices for MEMS, three-dimensional (3D) micromachining that can form certain round or curved structures is required. Recently, a high aspect ratio micromachining process using synchrotron radiation (SR) direct photo-etching of polymers without any process gases, the so called TIEGA (Teflon included etching galvanicforming), has been developed. The etching rate is of the order of 10-100 μm/min. Therefore, the processing for a 1000 μm-depth microstructure takes about 10 minutes, much shorter than that required for the deep X-ray lithography (LIGA) process. Moreover, it is free from problems of sticking due to the surface tension of the developer, the rinsing process etc., as SR etching is a completely dry process. Due to the high processing speed and smoothness of the etched surfaces, SR etching might have a potential for 3D micromachining by combining a scanning stage with a high degree of freedom. It is expected that microstructures formed by SR etching will be applied not only to highly functional mircodevices, but also in the biomedical field, due to the material characters of PTFE. In this paper, we propose SR etching as a new approach to form 3D microstructures of PTFE and describe results of preliminary experiments for 3D micromachining