Electrical Properties and Shrinkage of Carbonized Photoresist Films and the Implications for Carbon Microelectromechanical Systems Devices in Conductive Media

Recent advances in fabricating 3D micro- and nanostructures using carbon microelectromechanical systems, or C-MEMS, has opened up a wide variety of new and exciting applications. The development of 3D C-MEMS has been catapulted forward by the use of transparent, high-viscosity resists such as SU-8. The electrical characteristics and shrinkage of various thickness carbon films derived from SU-8 and AZ P4620 are quantified and discussed in the context of the decomposition and carbonization mechanisms of epoxy and phenolic resins. Measurements obtained reveal a thickness dependence of the resistivity at lower carbonization temperatures but not much dependence at 1000DGC. Possible explanations for this low-temperature thickness dependence are given. The electrical characteristics of carbon films obtained from both types of photoresists carbonized at 1000DGC are very similar to that of glassy carbon. Simulations have been carried out to demonstrate the importance of the carbon resistivity for C-MEMS devices when used in conductive media. A method for simple optimization and verification of C-MEMS device designs for use in conductive media is introduced.