Guidelines for etching silicon MEMS structures using fluorine high-density plasmas at cryogenic temperatures

摘要: This paper presents guidelines for the deep reactive ion etching (DRIE) of silicon MEMS structures, employing SF/sub 6//O/sub 2/-based high-density plasmas at cryogenic temperatures. Procedures how to tune equipment optimal results with respect etch rate and profile control are described. Profile is a delicate balance between respective deposition rates SiO/sub x/F/sub y/ passivation layer on sidewalls bottom an etched structure in relation removal from unpassivated areas. Any parameter that affects relative these processes has effect control. The mainly determined by oxygen content 6/ gas flow electrode temperature. Removal kinetic energy (self-bias) ions 2/ plasma. Diagrams given as function settings, previously published "black method". Parameter settings high bulk etching, micro needles moulds discussed, which demonstrate usefulness diagrams design features. Furthermore, it demonstrated order use DRIE, necessary avoid or least restrict presence fused silica dome material, because this material may release due corrosion during operation plasma source. When inert materials like alumina used, recipes can be defined broad variety microstructures temperature regime. Recipes relatively low (1-10% total volume) now applied observe lateral beneath mask, selectivity (more than 500) polymers oxide mask obtained. Crystallographic preference observed wafer (-120/spl deg/C). enhanced increasing process pressure above 10 mtorr energies (below 20 eV).