Near-field etching on plastic film

Our paper was published in Advances in Optical Technologies

Takashi Yatsui, Wataru Nomura, and Motoichi Ohtsu, “Realization of Ultraflat Plastic Film using Dressed-Photon–Phonon-Assisted Selective Etching of Nanoscale Structures,” Advances in Optical Technologies, February 2015, Article ID 701802

[Significance of this article]

Organic materials have considerable potential for application in future wearable technology devices. However, due to the nature of these substances, traditional surface treatment methods are unsuitable, which leads to difficulties with surface roughness. While techniques such as chemical mechanical polishing have been developed to overcome this issue, these methods cause deformation and contamination of the surface, ultimately resulting in performance degradation. Previously, we have developed the near-field (NF) etching technique, which is capable of removing surface roughness on organic material substrates without deforming or contaminating the surface. Here, the performance of this NF etching method is compared to that of a conventional photochemical etching procedure, using a polymethyl methacrylate (PMMA) and an O2 gas. A continuous-wave He-Cd laser is used for the NF etching procedure and a 5th-harmonic YAG laser is used to complete the photochemical etching. From atomic force microscopy images of the substrate sample before and after etching, it is apparent that a similar reduction in surface roughness occurs using both methods, which the photochemical etching procedure has a lower time cost. However, when the standard deviations of the height difference functions of the substrate surfaces are considered, it is found that the NF etching process selectively etched small scale structures, unlike the photochemical etching, which was effective for large scale structures only. Therefore, this technique, or a combination of both NF and photochemical etching, has potential for use in the production of ultraflat plastic films with low surface roughness values.