Patent ID: 7709285

Claim:
A method of manufacturing an electronic device comprising a micro-electromechanical systems (MEMS) element, which MEMS element comprises a first and a second electrode, which second electrode is movable towards and from the first electrode, which method comprises the steps of: providing an etch stop layer of electrically insulating material at a first side of a substrate, the substrate being etchable by dry etching using fluorine chemistry; providing a base layer of an electrically conductive material on the etch stop layer at the first side of the substrate, the first electrode being defined in the base layer; providing a sacrificial layer which at least covers the first electrode in the base layer; providing a mechanical layer of an electrically conductive material on top of the sacrificial layer, said mechanical layer being mechanically connected to the substrate; providing the second electrode by defining same in the mechanical layer or as a separate layer in or on the sacrificial layer; providing a mask on top of the mechanical layer, the mask including at least one window to the sacrificial layer; and removing selective areas of said sacrificial layer by means of dry chemical etching, such that the second electrode is made movable towards and from the first electrode, wherein said dry chemical etching is performed using a fluorine-containing plasma, and the etch stop layer comprises a substantially non-conducting, fluorine chemistry inert material.