Test Structures for Characterising the Fabrication of Miniature Reference Electrodes

Robust and reliable micro-scale integrated electrochemical sensors need a reference electrode that can provide a stable electrochemical potential. This can be achieved using a silver/silver chloride (Ag/AgCl) electrode, produced by the chemical chlorination of a thin patterned silver layer. Well understood and controlled processes are required to produce the Ag/AgCl electrode. This paper shows how previously reported test structures have been used to characterise and inform the fabrication procedure. Wafer mapping of these structures was carried out using a Python controlled measurement system, consisting of a semi-automatic prober connected to an HP4062UX based analyser. The measurements were analysed to determine whether the chlorination process was affected by the test structure geometry. This was found to have no clear effect on chlorination.