We have demonstrated that carbon-microelectromechanical systems ͑C-MEMS͒, in which patterned photoresist is pyrolyzed in inert environment at high temperature, constitutes a powerful approach to building 3D carbon microelectrode arrays for 3D microbattery applications. High aspect ratio carbon posts ͑Ͼ10:1͒ are achieved by pyrolyzing SU-8 negative photoresist in a simple one step process. Lithium can be reversibly charged and discharged into these C-MEMS electrodes. Because of the additional volume of the posts, higher capacities are achieved with the 3D array electrodes as compared to unpatterned carbon films with the same projected electrode area. These novel electrode arrays represent one of the critical components for 3D batteries, which may be interconnected with C-MEMS leads to enable smart power management schemes.

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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 1000°C. Possible explanations for this low-temperature thickness dependence are given. The electrical characteristics of carbon films obtained from both types of photoresists carbonized at 1000°C 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.Carbon chemistry is uniquely complex and versatile due to the ability of carbon atoms to form long chains and because of the changes in chemical and physical properties that occur due to the different bond types between carbon atoms. The versatility of carbon materials comes from the three different bonds that carbon atoms can make: sp 1 , sp 2 ͑graphitelike͒, and diamondlike ͑sp 3 ͒. Since ancient times, man has been creating carbon from various precursors. 1 One method of creating artificial carbon is through heat-treatment of hydrocarbons. The formation of carbon from gaseous precursors was an undesired side reaction in petrochemistry in the past, 2 but carbonization of organic materials has become a valuable method of obtaining various carbons. When organic materials are exposed to high temperatures in an inert atmosphere, the materials decompose into simpler compounds ͑referred to as chain scission, pyrolysis, thermolysis, or thermal cracking͒. Some of these intermediate species may then react to form a solid carbon char ͑C ϱ ͒. Chemisorption of gas-phase organics ͑especially benzene͒ is thought to be the dominant carbon-forming mechanism for chemical vapor deposition ͑CVD͒ of pyrocarbons. 2-8 The predominant carbonization mechanisms for in situ carbonization of polymers is cross-linking, sidechain elimination ͑including dehydrogenization͒, and side-chain cyclization of polymers. 9,10 Although the term pyrolysis has been used in the literature to refer to the chain scission of organic compounds as well as to the formation of solid carbon from organic compounds, the term carbonization is used in this paper to refer to the creation of solid carbon ͑C ϱ ͒ through processes including scission. Heattreatment ͑usually above 2600°C͒ of these pyrocarbons, in conjunction with application of pressure, can cause the material to exhibit long-range graphitic order in a process ter...

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