Proceedings Article | 23 February 2005
KEYWORDS: Polymers, Semiconducting wafers, Optical lithography, Gold, Polymer thin films, Metals, Thin films, Resistance, Semiconductors, Microfluidics
We present a novel technology for a cyclo-olefin-copolymer (COC) plastic microfluidic platform for heat control with fully semiconductor process-compatible photolithographic 5 μm-wide metal patterns, for heaters, electrodes, and temperature sensors and a thin membrane structure. Through tests of compatibility of some thermoplastic materials with chemical solutions and temperature tolerance to the semiconductor processes (thin film depositions, photolithography, and etchings), we selected COC as a semiconductor process-compatible plastic material for biomedical applications. For photolithography processes, we manufactured the 5’ COC wafer with flat surface with c.a. 3 nm surface roughness, employing a novel flame-torched injection-molding method. Furthermore, the part of heating blocks on COC wafers is controlled thickness to the 100 μm, to enhance the heat-ramping speeds through reduction of the thermal mass. In order to fabricate the Au thin film micro-patterns for temperature sensors, heaters, and electrodes, Au film (100 nm) was deposited by e-beam evaporator and patterned by using standard photolithography, and wet-etched. The micro-patterned Au temperature sensors, heaters, and electrodes was demonstrated. For insulating layers, Al2O3 film was deposited by an ALD system, patterned by using the standard photolithography, and wet-etched. Using the COC microfluidic platform, we tested thermal cycling with simple heating and natural cooling on chip with water and, heating rates (5°C/s when heating, 3°C/s when cooling) are obtained. Therefore, the COC microfluidic platform can be applied to a DNA lab-on-a-chip.
