Surface micromachining of Ceramic-MEMS based on SU-8 micromoulding of Polyureasilazane

Chemical inertness and corrosion resistance make ceramic materials appropriate for Micro Electro-Mechanical Systems (MEMS) when aiming for sensing applications at high temperature or in harsh environment. Besides the usual fabrication techniques, such as powder-injection moulding, applied for macro structures, new methods were recently developed based on the use of liquid precursors for engineering of ceramic MEMS. Microinjection and photopolymerisation of e.g. Polyureasilazane (a precursors for SiC and Si-C-N) has been successfully used to form ceramic microstructures. Here, we describe a novel surface micromachining process based on high-aspect ratio micro-moulds made of SU-8 (thickness: 500um, width: 100-1000um) for lateral structuring of a liquid precursor, the use of Cr/Al sacrificial layer to detach the green bodies, the pyrolysis step and material characterization in view of MEMS applications. Dynamic rheological (DRA) and thermogravimetric (TGA) analysis, under UV and temperature control, will be presented and compared to those obtained in the literature. Electro-mechanical characterisation of ceramic beams is also presented.