MEMS process and device

A method as claimed in 1, wherein the step of removing the first and second sacrificial layers comprises:

• removing an inner area of the first sacrificial layer;
• removing the second sacrificial layer;
• and
• removing an outer area of the first sacrificial layer.

A method of fabricating a micro-electrical-mechanical system (MEMS) microphone, the method comprising the steps of:

• depositing first and second electrodes;
• depositing a membrane that it is mechanically coupled to the first electrode;
• and
• depositing a back plate that it is mechanically coupled to the second electrode;
• wherein the step of depositing the second electrode comprises the step of forming a predetermined pattern in the second electrode, and wherein the predetermined pattern comprises one or more openings.

A method of testing a plurality of micro-electrical-mechanical system (MEMS) microphones formed on a wafer, each MEMS microphone comprising a membrane and at least one sacrificial layer, the method comprising the steps of:

• attaching the wafer to a carrier:
• singulating the wafer to form two or more MEMS microphones;
• removing the at least one sacrificial layer;
• and
• testing the MEMS microphones while attached to the carrier.