Batch-mode micropatterning of carbon nanotube forests using UV-LIGA assisted micro-electro-discharge machining

This paper reports batch-mode, three-dimensional micropatterning for arrays of vertically aligned carbon nanotubes, also known as CNT forests, based on dry micro-electro-discharge machining (μEDM). The process employs an array of copper electrodes microfabricated through an advanced UV-LIGA process enabled with a new photoresist system in combination with electroplating, providing a low-cost path to constructing high-density arrays of μEDM electrodes for high-throughput parallel processing. The fabricated arrays of 85-μm-tall electrodes are utilized to demonstrate and characterize planar dry μEDM for post-growth patterning of CNT forests in air. Die sinking and scanning processes are tested to show pattern transfers with a 4-μm tolerance and an average surface roughness of 230 nm. An elemental analysis suggests that contamination of the electrode material on the produced patterns is minimal. Key characteristics in the use of planar electrodes for batch processing of CNT forests are revealed through experimental analysis and discussed in detail. The results suggest that the investigated process is a promising approach toward offering a cost-effective manufacturing technology for future products functionalized with custom-designed microstructures of CNT forests.