Microprocessing using Soft X-ray from Laser Produced Xe Plasma

Abstract

Microprocessing of poly(tetrafluoroethylene) (Teflon) and poly(methyl methacrylate) (PMMA) samples was carried out using soft X-ray from a laser produced Xe plasma source we developed. In the Teflon sample, a contact angle of a modified surface with a water drop increased from 90° to 110° to by an irradiation without a mirror and a mask, while the angle decreased to 50° by an irradiation with them. Scanning electron microscopy showed numerous microprotuberances and a masked pattern having micro-concavities on the each sample surface. These suggested that the changes of the contact angle were ascribable to the microstructures of the Teflon surface. We succeeded in controlling the wettability of the Teflon surface from hydrophobic to hydrophilic by microprocessing using the laser plasma X-ray. In the PMMA sample, its etching rate was investigated using an irradiation with a large number of pulses (192000 pulses) and a low power density of 8×10⁴ W/cm². The etching rate was calculated to be 5 pm/pulse and this was concluded to be a result by only photo-etching without thermal effect. We demonstrated pure photo-etching depth of ∼1 µm.