Method and system for forming a capacitive micromachined ultrasonic transducer
First Claim
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1. A method comprising:
- forming oxide features over a capacitive micromachined ultrasonic transducer (CMUT) control chip that is in or over a silicon wafer, the CMUT control chip configured to control a capacitive micromachined ultrasonic transducer;
planarizing the oxide features;
bonding a silicon-on-insulator (SOI) wafer to the planarized oxide features;
depositing a first metal layer over the silicon wafer and the CMUT control chip, wherein the first metal layer forms first and second plate couplers in electrical contact with the CMUT control chip;
depositing a second metal layer over the first metal layer, wherein the second metal layer forms a first plate of a CMUT capacitor, wherein the first plate is in electrical contact with the first plate coupler; and
depositing a third metal layer over the second metal layer, wherein the third metal layer forms a second plate of the CMUT capacitor, wherein the second plate is in electrical contact with the second plate coupler.
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Abstract
A method for forming a capacitive micromachined ultrasonic transducer (CMUT) is provided that includes forming oxide features outwardly of a CMUT control chip in a silicon wafer. The oxide features are planarized. A silicon-on-insulator (SOI) wafer is bonded to the planarized oxide features. For a particular embodiment, the SOI wafer comprises a single crystal epitaxial layer, a buried oxide layer and a silicon layer, and the single crystal epitaxial layer is bonded to the planarized oxide features, after which the silicon layer and the buried oxide layer of the SOI wafer are removed, leaving the single crystal epitaxial layer bonded to the oxide layer.
82 Citations
20 Claims
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1. A method comprising:
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forming oxide features over a capacitive micromachined ultrasonic transducer (CMUT) control chip that is in or over a silicon wafer, the CMUT control chip configured to control a capacitive micromachined ultrasonic transducer; planarizing the oxide features; bonding a silicon-on-insulator (SOI) wafer to the planarized oxide features; depositing a first metal layer over the silicon wafer and the CMUT control chip, wherein the first metal layer forms first and second plate couplers in electrical contact with the CMUT control chip; depositing a second metal layer over the first metal layer, wherein the second metal layer forms a first plate of a CMUT capacitor, wherein the first plate is in electrical contact with the first plate coupler; and depositing a third metal layer over the second metal layer, wherein the third metal layer forms a second plate of the CMUT capacitor, wherein the second plate is in electrical contact with the second plate coupler. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method comprising:
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forming oxide features over a capacitive micromachined ultrasonic transducer (CMUT) control chip that is in or over a silicon wafer, the CMUT control chip configured to control a capacitive micromachined ultrasonic transducer; fly cutting the oxide features to planarize the oxide features; bonding a single crystal silicon layer of a silicon-on-insulator (SOI) wafer to the planarized oxide features, wherein the SOI wafer comprises the single crystal silicon layer, a buried oxide layer, and a silicon layer; forming first and second plate couplers over the silicon wafer and in electrical contact with the CMUT control chip; forming a first plate of a CMUT capacitor over the first and second plate couplers, wherein the first plate is in electrical contact with the first plate coupler; and forming a second plate of the CMUT capacitor over the first plate, wherein the second plate is in electrical contact with the second plate coupler. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17)
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18. A method comprising:
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forming first and second plate couplers over a capacitive micromachined ultrasonic transducer (CMUT) control chip, the CMUT control chip configured to control a capacitive micromachined ultrasonic transducer; forming a first plate of a CMUT capacitor over the first and second plate couplers, wherein the first plate is in electrical contact with the first plate coupler; forming one or more oxide features over the first plate; planarizing the one or more oxide features; bonding a single crystal silicon layer of a silicon-on-insulator (SOI) wafer to the one or more planarized oxide features, wherein the SOI wafer comprises the single crystal silicon layer, a buried oxide layer, and a silicon layer; removing the silicon layer and the buried oxide layer of the SOI wafer, wherein the single crystal silicon layer remains bonded to the one or more planarized oxide features; and forming a second plate of the CMUT capacitor over the single crystal silicon layer, wherein the second plate is in electrical contact with the second plate coupler. - View Dependent Claims (19, 20)
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Specification