Fabrication of Micro-Pillar by plasma etching texturing of Carbon-Based thin film

Abstract

Surface texturing of a carbon-based thin film is the critical technology in the development of functional surface for many kinds of sensors. This study explored the possibilities of processing the carbon film’s surface by means of plasma etching to produce micro-pillars. Circular dots with a diameter of 25 μm, 50 μm, and 100 μm were printed on a thick carbon film. A high density oxygen plasma was generated by a combination of RF and DC power in a vacuum chamber. The high density plasma was applied onto the surface of a diamond-like carbon film. The printed pattern serves as a mask-like in the lithography technique. The oxidation reaction was expected on the exposed surface, i.e. the area surrounded the dots. The results show the oxidation effectively removed the carbon on the unmasked area producing 3D circular patterns. The plasma processing, which was carried out for 2 h, was monitored and diagnosed using optical emission spectroscopy (OES). The oxidation was controlled by atomic oxygen which was the dominant species observed in the plasma. The removal (etching) rate was 9 μm/h with 91%, 98% and 99% pattern accuracy related to the larger diameter studied in this work. Observations using a Raman spectroscopy confirmed that the printed mask effectively protects the DLC from the etching process and other indirect processes.