Micro-electromechanical systems based on 3C-SiC/Si heterostructures

Wide band gap semiconductors like SiC are excellent materials for high temperature, high frequency and high power applications. Furthermore, the properties of SiC fulfil the requirements for modern applications in micro-sensors, micro-actuators as well as in micro- and nano-electromechanical systems (MEMS and NEMS). Novel applications of SiC/Si based MEMS and NEMS are dosing and sensor systems for micro- and nano-fluidic systems, e.g. for fast and reliable biomedical testing and analysis. We have developed a technology for processing SiC/Si-based MEMS and NEMS. A micro dosing head for pulmonary amounts of water-based liquids was realized. This dosing head consist of parallel operating multi micro pipes running at a defined pressure. Furthermore, we used 3C-SiC/Si heterostructures to process resonator bars having geometries in the μm range and a thickness of 250 nm. These bars open the possibility to evaluate the viscosity of water nano-droplets, to measure the mass of biomolecules, especially proteins, positioned on the bars. The used 3C-SiC layers were grown by a special chemical vapor deposition under ultra high vacuum (UHVCVD) conditions. This kind of deposition process allows us to grow the cubic silicon carbide polytype at relatively low temperature (below 900 °C). Such growth conditions allow reducing the internal stress of the grown monocrystalline layers, which is an important precondition for fabrication of reliable MEMS and NEMS structures based on silicon carbide.