Sub-wavelength micromachining of silica glass by irradiation of infrared laser with Fresnel diffraction

• Published in: TENCON 2010 - 2010 IEEE Region 10 Conference pp. 1905 - 1908
• Main Authors: Okazaki, K, Nakamura, D, Okada, T, Niino, H, Torii, S, Makimura, T, Murakami, K, Takahashi, A
• Format: Conference Proceeding
• Language: English
• Published: IEEE 01.11.2010
• Subjects: Apertures; CO2 laser; Copper; Fresnel diffraction; Glass; Laser ablation; metal mask; Micromachining; silica glass; Silicon compounds
• DOI: 10.1109/TENCON.2010.5686422
• ISBN: 9781424468898; 1424468892
• ISSN: 2159-3442

We investigated a simple and productive micromachining method of silica glass by the ablation using a 10.6 μm TEA CO 2 laser with a spatial resolution down to sub-wavelength scale. Copper grid mask with square apertures of 20×20 μm was attached to the silica glass surface, and the silica glass was irradiated by the TEA CO 2 laser light through the mask. As a result, circular holes were formed on the silica glass surface at the center of the apertures due to the Fresnel diffraction effect, and a minimum diameter of the hole was less than 3 μm. The mechanism of the micromachining was discussed based on the electric field distribution of the CO 2 laser light under the mask, by a 3D full-wave electromagnetic field simulation.