Micromachining of Polymethylmethacrylate and Polydimethylsiloxane Using Laser Plasma Soft X-rays

We have investigated micromachining of polymethylmetacrylate (PMMA) and polydimethylsilioxan (PDMS) by irradiation with laser plasma soft X-rays. We generated wide band soft X-rays around 10 nm by irradiation of Ta targets with Nd:YAG laser light. In addition, narrow band soft X-rays at 11 nm and 13.5 nm were generated by irradiation of solid Xe and Sn targets, respectively, with pulsed CO2 laser light. The generated soft X-rays were focused on samples, using an ellipsoidal mirror. The soft X-rays were incident through windows of contact masks on the samples. We found that PMMA sheets were ablated by irradiation with soft X-rays at 13.5 nm. PDMS sheets are also ablated by soft X-ray irradiation at 1x10(8) W/cm(2), while PDMS surfaces were swelled by irradiation with soft X-rays at 3x10(6) W/cm(2). It is remarkable that through holes with a diameter of 1 mu m can be fabricated in PMMA and PDMS sheets with a thickness of 4 mu m. Thus, we have developed a practical technique for micromachining of PMMA and PDMS sheets in a micrometer scale. DOI:10.2961/jlmn.2011.03.0012