Fabrication and characterization of freestanding 3D carbon microstructures using multi-exposures and resist pyrolysis

Abstract

We present a fabrication method for freestanding complex 3D carbon microstructures utilizing a lithogaphy step and a heating step. We developed two fabrication methods for multi-level 3D SU-8 microstructures, which were used as polymer precursors in a carbonization process. In one method, multiple SU-8 layers were successively coated and cross-linked. In the other method, aligned partial exposures were used to control the thickness of the freestanding SU-8 layer. Freestyle, freestanding carbon microstructures were fabricated by heating 3D SU-8 microstructures below 1000 • C in a nitrogen atmosphere. Characterization of the pyrolysis process, through measurements such as dimensional changes, roughness, hardness, elastic modulus and resistivity, was performed for positive resists AZ5214 and AZ9260 as well as SU-8. 3D carbon microstructures fabricated using our methods can be utilized for various applications such as low cost resonating microsensors and microfluidics.

Novel Nanostructured Electrodes Obtained by Pyrolysis of Composite Polymeric Materials

“…Eventually, the TGA profiles are stabilized between 600 °C and 900 °C. A similar behavior of SU‐8 films during TGA has been observed in previous studies 11,29.…”

Optimized SU-8 Processing for Low-Cost Microstructures Fabrication without Cleanroom Facilities

“…The patterning of the SU-8 by lithography allows microstructures of almost any shape and size; not only planar microstructures, but also multilayer and 3D microstructures [8]. For that, several lithographic techniques can be used, such as, layer-by-layer multi exposure lithography [8,9], inclined/rotated lithography [8,10], holographic lithography, and gray-scale lithography [8,11]. Figure 1 shows the SU-8 processing steps and the respective equipment used that allows the fabrication of microstructures with aspect ratios of more than 20, with low-cost and without cleanroom facility.…”

Nanomechanical Pyrolytic Carbon Resonators: Novel Fabrication Method and Characterization of Mechanical Properties

“…Pyrolytic carbon is conductive and can be obtained directly from photoresist through pyrolysis at elevated temperatures in inert atmosphere. The advantage of this fabrication method is that the geometry of carbon micro- and nanostructures such as micropillar arrays [ 8 ], bridges [ 9 ] and suspended nanowires [ 10 ] can be defined through simple photolithographic processes followed by pyrolysis. A few different approaches to fabricate carbon-based doubly-clamped beams [ 11 ] and cantilevers [ 12 ] were presented using soft lithography or multiple steps of photolithography.…”