Electrochemical Etching and LIGA Technique

The EC-FPN technique is shown to be an efficient and clean technique for localized fabrication of a variety of vertically grown metal nanowires and can potentially be used for fabricating freeform 3D nanostructures. 

Electrochemical etching with ultrashort voltage pulses allows to dissolve electrochemically active materials within an extremely narrow volume and to manufacture three dimensional (3D] microstructures. Micro- and nanoporous silicon can be generated 

Such confined etchant layer technique has been applied to achieve effective three-dimensional (3D) micromachining on n-GaAs and p-Si. It operates via an indirect electrochemical process and is a maskless, low-cost technique for microfabrication of arbitrary 3D structures in a single step [109]. It has also been presented that free-standing Si quantum wire arrays can be fabricated without the use of epitaxial deposition or lithography 

However, the ultraprecise microstructures with extreme aspect ratio could only be generated by deep X-ray lithography. Difficulties, for example, in the access to synchrotron radiation facilities have limited the commercialization of LIGA technique in mass fabrication. 

7 Micro- and Nano-Machining by Ultrashort Voltage Pulsing Technique 

---