In order to implement electrochemical processes (e.g., detection or synthesis) on a chip-based system, micromachining techniques for a glass microchip with fully integrated electrodes have been developed. Pt/Ti microelectrodes were successfully patterned on the curved surface of a glass microchannel, which was etched in a HF solution using polysilicon thin film as an etch mask, by means of a lift-off method using a positive thick photoresist. In this process, the photoresist must be exposed with a single wavelength (g line) selected from a high-pressure mercury lamp in order to obtain its microstructure with excellent edge quality and vertical sidewalls. In addition, although fusion bonding cannot be used for microchips with lead patterns in the interface between a pair of glass substrates, a glass cover plate can be bonded to a glass substrate with lead patterns embedded in the space formed on its surface by buffered HF (BHF) etching. The resulting bonded area ratio was estimated to be approximately the same as that for glass-to-glass bonding.
