MEMS process and device
First Claim
1. A method of fabricating a micro-electrical-mechanical system (MEMS) microphone on a substrate, the method comprising:
- depositing first and second electrodes;
depositing a membrane, the membrane being mechanically coupled to the first electrode; and
depositing a back plate, the back plate being mechanically coupled to the second electrode;
wherein the step of depositing the membrane further comprises the step of depositing the membrane on a first sacrificial layer; and
wherein the method further comprises the steps of;
depositing a second sacrificial layer in an area between the first and second electrodes; and
removing the first and second sacrificial layers so as to form a MEMS microphone having a first cavity beneath the membrane, and a second cavity between the first and second electrodes, such that the membrane and the first electrode are able to move relative to the second electrode.
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Accused Products
Abstract
A MEMS device comprising a flexible membrane that is free to move in response to pressure differences generated by sound waves. A first electrode mechanically coupled to the flexible membrane, and together form a first capacitive plate. A second electrode mechanically coupled to a generally rigid structural layer or back-plate, which together form a second capacitive plate. A back-volume is provided below the membrane. A first cavity located directly below the membrane. Interposed between the first and second electrodes is a second cavity. A plurality of bleed holes connect the first cavity and the second cavity. Acoustic holes are arranged in the back-plate so as to allow free movement of air molecules, such that the sound waves can enter the second cavity. The first and second cavities in association with the back-volume allow the membrane to move in response to the sound waves entering via the acoustic holes in the back-plate.
188 Citations
46 Claims
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1. A method of fabricating a micro-electrical-mechanical system (MEMS) microphone on a substrate, the method comprising:
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depositing first and second electrodes; depositing a membrane, the membrane being mechanically coupled to the first electrode; and depositing a back plate, the back plate being mechanically coupled to the second electrode; wherein the step of depositing the membrane further comprises the step of depositing the membrane on a first sacrificial layer; and
wherein the method further comprises the steps of;depositing a second sacrificial layer in an area between the first and second electrodes; and removing the first and second sacrificial layers so as to form a MEMS microphone having a first cavity beneath the membrane, and a second cavity between the first and second electrodes, such that the membrane and the first electrode are able to move relative to the second electrode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 37, 38, 39, 40, 41)
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14. A method as claimed in 1, wherein the step of removing the first and second sacrificial layers comprises:
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removing an inner area of the first sacrificial layer; removing the second sacrificial layer; and removing an outer area of the first sacrificial layer. - View Dependent Claims (15, 16)
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- 35. A method as claimed in 1, further comprising the step of forming a plurality of openings in the back plate.
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42. A method of fabricating a micro-electrical-mechanical system (MEMS) microphone, the method comprising the steps of:
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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. - View Dependent Claims (43, 44)
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45. 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:
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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. - View Dependent Claims (46)
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Specification