Silicon membranes fabrication by wet anisotropic etching

The anisotropic etching of silicon became a key technology for sensor fabrication due to the strong dependence of the etch rate on crystal orientation which offers the possibility of 3D structuring. The paper presents the investigation of anisotropic etching of silicon in organic (ethylenediamine pyrocatechol (EDP)) and inorganic (KOH, KOH + complexant) solutions for sensor membrane fabrication. The protection of metallic layer during the anisotropic etching is considered. The solutions were analyzed and compared in point of view of etch rate and quality of silicon etched surface. The mask materials resistant at etching solutions are presented. The improvement of the anisotropic etching process is realized by using organic complexants added at KOH, which increases the etch rate and minimizes the hillocks formation. The EDP etching is analyzed for metallic layer protection and contamination avoidance. New materials obtained at low temperature deposition (<400 °C) used as mask material for metal protection are investigated.