FABRICATION OF ELECTRODE ARRAYS IN THE QUARTER MICRON REGIME FOR BIOTECHNOLOGICAL APPLICATIONS

In the field of biotechnological microsystems there is a strong demand for the fabrication of ultraminiaturised electrodes. Examples are hig hly sensitive biosensors or electric field induced handling of biologi cal cells and macromolecules. New effects and thus new fields of appli cations appear when the electrode dimensions reach the 100 nm scale. T his paper presents two alternative technologies for the fabrication of biocompatible microelectrodes: a platinum lift-off process and a gold electroplating process. The lithography was performed with a Leica EB PG 4 HR electron-beam writer at 50 kV acceleration voltage. An electro de size dependent exposure dose was calculated from the effect of back scattered electrons (proximity effect). Evaporated platinum lines with 200 nm spaces could be realized. The electrodes are embedded in SiO2 yielding a nearly planar surface. In the second case 140 nm gold lines with 60 nm spaces were electroplated using a sulphitic plating soluti on.