Layered microphone structure

The microphone according to any one of the preceding claims, wherein the spacer layer is shaped to provide support to the moveable electrode over at least a peripheral region of the moveable electrode, and to provide at least one active region of the moveable electrode located inwardly of the peripheral region in which there is a gap between the moveable and fixed electrodes for deflection of the moveable electrode.

The microphone according to any one of the preceding claims, wherein the at least one spacer layer comprises an annulus-shaped spacer layer.

The microphone according to any one of the preceding claims, wherein the at least one spacer layer comprises a plurality of spacer layers.

The microphone according to any one of the preceding claims, wherein the at least one spacer layer is shaped to provide at least one side vent for facilitating transfer of acoustic signals into and out of the microphone.

The microphone according to any one of the preceding claims, wherein the spacer layer comprises a plurality of arc-shaped spacer layers which support peripheral regions of the moveable electrode such that there is a gap between neighbouring arc-shaped spacer layers, whereby a plurality of side vents are formed for introducing acoustic signals into the microphone.

The microphone according to any one of the preceding claims, wherein the spacer layer includes at least one separate island-like structure for providing support to the at least one inwardly located region of the moveable electrode.

The microphone according to any one of the preceding claims, wherein the spacer layer comprises fingers extending in a generally radially-inward direction from a perimeter of the moveable electrode for providing support to the at least one inwardly located region of the moveable electrode.

The microphone according to any one of the preceding claims, wherein the spacer layer is such that it defines a plurality of isolated active regions of the moveable electrode in which there is a gap between the moveable and fixed electrodes for deflection of the moveable electrode.

The microphone according to any one of the preceding claims, wherein the moveable electrode is secured to a face of a diaphragm such that it can deflect with the diaphragm.

The microphone according to any one of the preceding claims, wherein the fixed electrode is secured to a back plate.

The microphone according to any one of the preceding claims, further comprising clamping means for clamping selected areas of the moveable electrode against the spacer layer.

The microphone according to any one of the preceding claims, wherein the microphone is omnidirectional.

The microphone according to any one of the preceding claims, wherein acoustic signals are guided into the microphone with a housing.

A stacked microphone formed from a plurality of sub-microphones, each sub-microphone being in accordance with a microphone as claimed in any one of the preceding claims, wherein the sub-microphones are stacked one on top of the other such that all moveable and fixed electrodes are substantially parallel.

A method of fabricating components of a capacitive microphone formed from layers, the method including the step of fabricating at least one layer of the microphone using a LIGA process.

A method of fabricating components of a capacitive microphone formed from layers comprising a back plate, a diaphragm, and a spacer layer for separating the back plate from the diaphragm, and a clamping layer for clamping the diaphragm against the spacer layer, the method comprising the steps of:

• providing a pattern for each of the layers;
• transferring the pattern onto each layer using a beam of laser light.