Micromachining Using Soft X-Rays from Laser-Produced Xe Plasma

摘要

Micromachining of poly(tetrafluoroethylene) (Teflon) and poly(methyl methacrylate) (PMMA) samples was carried out using soft X-rays from a laser-produced Xe plasma source, which we developed. In the Teflon sample, the contact angle with a water droplet on a modified surface increased from 90° to 110° as a result of irradiation without a mirror or mask, while the angle decreased to 50° when using irradiation with them. Scanning electron microscopy showed numerous micro-protuberances and a masked pattern with micro-concavities on each sample surface. These results suggested that a change to the contact angle was caused by the microstructures on the Teflon surface. We succeeded in controlling the wettability of the Teflon surface, from hydrophobic to hydrophilic, by micromachining using laser plasma X-rays. In the PMMA sample, the etching rate was investigated with irradiation using a large number of pulses (192,000 pulses) and a low power density of 8 × 10~4 W/cm~2. The etching rate was calculated to be 5 pm/pulse. This was judged to be due only to photo-etching without any thermal effects. We demonstrated a pure photo-etching depth of about 1 μm.