Analytical Sciences

Rapid Plasma Etching for Fabricating Fused Silica Microchannels

Kyojiro MORIKAWA,* Kazuki MATSUSHITA,** and Takehiko TSUKAHARA**

*Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
**Laboratory for Advanced Nuclear Energy, Institute of Innovative Research, Tokyo Institute of Technology, 2-12-1-N1-6, Ookayama, Meguro, Tokyo 152-8550, Japan

In order to advance the performances of micro chemical and biochemical systems on a chip, the fabrication of microstructures such as channels and pillars is an essential basic technology. However, conventional fabrication methods based on wet etching have limitations in their applications for device engineering. In this study, we report on a new microchannel fabrication process on a fused silica substrate using photoresist and plasma etching based on C₃F₈, CHF₃, and Ar gases. Deep, rectangular microchannels, having vertical angles close to 90°, 10 μm-scale deep and low surface roughness of less than 1 nm, could be fabricated on a fused silica substrate at high etching rates on the order of 5 – 7 nm s⁻¹. This metal-free fabrication methodology is expected to be a low-cost, easy, and simple technique for a fused silica microstructure applications.

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