Electrochemistry on microcircuits. I: Copper microelectrodes in oxalic acid media

Microelectrode size and connections are the two main limitations to conceive microelectrode arrays with a micrometric scale to study the electrochemical phenomena involved in the damascene process. A new chip consisting of an array of microelectrodes realized in an industrial CMOS process addresses these issues. This new fabrication technique for the realization of copper microelectrode arrays was reported. The design and the manufacturing of this device were aimed at studying the behaviour of copper by electrochemical measurements at small scale in media of interest for the microelectronic industry.In this paper, the design and the manufacturing of microelectrode array composed of copper electrode couples of various geometries were described. An advanced photolithography technique developed for the semiconductor industry was used to fabricate them. The tools permitting their characterization are also presented in order to study the wet processes involved in the damascene process by various electrochemical techniques, namely voltammetry and electrochemical impedance measurements.