Patent ID: 7060197

Claim:
A method for manufacturing a micromechanical mass flow sensor, the method comprising: patterning an etching mask that is one of applied on a silicon layer that is applied above a silicon oxide layer on a silicon substrate and applied directly on the silicon substrate; producing vertical grooves by etching in the silicon layer and the silicon substrate, lands of silicon remaining behind between the vertical grooves; oxidizing the lands of silicon by thermal oxidation; covering the silicon dioxide block by deposing a silicon dioxide sealing layer, and leveling it to produce a smooth surface on a silicon dioxide block; wherein the etching mask is applied on the silicon layer, and before oxidation of the lands, the silicon oxide layer is at least partly removed by a gas-phase etching step to produce a horizontal cavity beneath a patterned region of the silicon layer; wherein to produce at least one pillar in the horizotal cavity, the silicon oxide layer is patterned before applying the silicon layer.