MEMS microphone and method for manufacture
View Patent ↗An improved method for manufacturing an MEMS microphone with a double fixed electrode is specified which results in a microphone which likewise has improved properties.
1. A microphone of miniaturized MEMS design
having a substrate comprising silicon and a patterned layer construction arranged thereon,
wherein the layer construction comprises partial layers arranged one above another for the following functional layers:
a bottom fixed electrode, thereabove
a membrane and thereabove
a top fixed electrode,
wherein the membrane is areally divided into
an outer edge region,
a freely oscillating region, which is completely enclosed by the outer edge region and in which the membrane is embodied in substantially planar fashion,
an anchor region within the outer edge region, in which the membrane is vertically fixed between bottom and top fixed electrodes, wherein the outer edge region substantially consists of the anchor region,
a connection region within the outer edge region, in which an electrical lead to the membrane is arranged,
wherein a perforation is arranged through the substrate below the entire freely oscillating region, and wherein the anchor region is arranged outside the area region of the perforation above an inner edge region of the substrate,
wherein the partial layers forming the membrane are electrically isolated from the remaining area regions of the corresponding partial layers by an incision running outside the outer edge region and omitting the connection region, and
wherein, at least outside the region enclosed by the incision, insulation layers are arranged between bottom fixed electrode and membrane and between membrane and top fixed electrode.
2. The microphone according to claim 1 ,
wherein all partial layers of the layer construction are produced directly one above another as a layer composite assembly, and wherein the membrane is fixed in the anchor region in the original layer composite assembly.
3. The microphone according to claim 1 ,
wherein the membrane has in the anchor region a first bulge, by which it is supported on the bottom fixed electrode.
4. The microphone according to claim 3 ,
wherein the top fixed electrode has in the anchor region a second bulge, by which it is supported on the membrane.
5. The microphone according to claim 4 ,
wherein first and second bulges bear on the respectively adjacent partial layer of the layer construction, such that the membrane is freely moveable in the anchor region within the layer plane, but fixed against a vertical deflection.