Wafer-level fabrication of polymer microsensors with integrated heat control

This paper described a novel wafer-level fabrication of polymer microsensors on the injection-molded thin polymer membrane with integrated heat control by conventional semiconductor processing techniques including standard photolithographic methods. A COC 5-in. wafer (1 mm thickness) is fabricated using injection molding method, in which polymer membranes (ca. 130 /spl mu/m thick and 3 mm /spl times/ 6 mm in area) are implemented simultaneously to reduce local thermal mass around micropatterned heaters and temperature sensors. The highly polished surface (ca. 4-nm) of the COC wafer makes it possible to use the standard photolithographic protocols. Gold micropatterns are fabricated for making microheaters, temperature sensors, and microelectrodes. An insulating layer of aluminum oxide (Al/sub 2/O/sub 3/) is prepared by using atomic layer deposition and micropatterning for the electrode contacts. The microdevice for heating and temperature sensing shows improved performance of thermal isolation, and microelectrodes display good electrochemical performances for electrochemical sensors.

INTRODUCTION

Polymer-utilized microdevices are very important contributors to the recent great advance of biochemical devices.^[1] Especially, disposable polymer microdevices have been adapted in many fluidics-based applications because of the low fabrication cost and the easiness of complex shape fabrication.^{[2] – [3]} Most of these polymer devices still consist of simple channels, valves, and chambers mainly, though polymer devices have been miniaturized for rapid and parallel processing. For further miniaturization and practical applications, many important functions like heating and detection should be included in the devices. Moreover, the fabrication cost should be decreased as low enough for disposable use.^[3]