Thick and thin diaphragms fabrication using gold-silicon eutectic

Our experiments highlight the fact that gold-silicon (Au-Si) eutectics are fairly inert to the attack of both anisotropic and isotropic wet etchants of Si (e.g. KOH, TMAH or HF/HNO₃ solutions). Therefore, this interfacial eutectic can be used as etch-stop layers in wet etching-based bulk micromachining. This paper shows how Au-Si eutectic layers may be employed for thick and thin diaphragm fabrication. The paper discusses three major directions of interest: eutectic formation, thick silicon diaphragm fabrication and thin Au-Si (eutectic) diaphragm generation. The application areas of these diaphragms include pressure sensors (high-pressure range) and microphones.