Method for sealing and backside releasing of microelectromechanical systems
First Claim
1. A method for encapsulating and integrating nano- and/or micro-electromechanical systems (MEMS) comprising:
- providing a semiconductor-on-insulator substrate comprising a handle layer, a device layer, and an insulating layer disposed between the handle and device layers;
fabricating a transistor-based circuit in the device layer;
fabricating a MEMS device in the device layer;
forming an etch resistant layer over the MEMS device and into the device layer;
forming a silicon dioxide sacrificial layer;
etching the handle layer beneath the MEMS device using the insulating layer as an etch stop; and
releasing the MEMS device from the device layer through the backside of the substrate using an etchant, wherein the etch-resistant layer is resistant to the etchant and the etch-resistant layer protects the transistor-based circuit from the etchant,wherein releasing the MEMS device comprises removing the silicon dioxide sacrificial layer in a hydrofluoric acid.
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Accused Products
Abstract
Disclosed are methods for fabricating encapsulated microelectromechanical systems (MEMS) devices. A MEMS device fabricated on a CMOS wafer is encapsulated using an etch resistant thin film layer prior to the release of the MEMS device. Once CMOS processing is completed, the wafer is etched to release the MEMS device. If the MEMS is fabricated on a silicon-on-insulator (SOI) wafer, the buried oxide of the SOI wafer acts as an etch stop for the etching. A sacrificial layer(s) is accessed and removed from the back side of the wafer, while the front side of the wafer is protected by a masking layer. The MEMS device is released without having any detrimental effects on CMOS components. If desired, the wafer can be mounted on another substrate to provide hermetic or semi-hermetic sealing of the device.
165 Citations
29 Claims
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1. A method for encapsulating and integrating nano- and/or micro-electromechanical systems (MEMS) comprising:
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providing a semiconductor-on-insulator substrate comprising a handle layer, a device layer, and an insulating layer disposed between the handle and device layers; fabricating a transistor-based circuit in the device layer; fabricating a MEMS device in the device layer; forming an etch resistant layer over the MEMS device and into the device layer; forming a silicon dioxide sacrificial layer; etching the handle layer beneath the MEMS device using the insulating layer as an etch stop; and releasing the MEMS device from the device layer through the backside of the substrate using an etchant, wherein the etch-resistant layer is resistant to the etchant and the etch-resistant layer protects the transistor-based circuit from the etchant, wherein releasing the MEMS device comprises removing the silicon dioxide sacrificial layer in a hydrofluoric acid. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method for encapsulating and integrating nano and/or microelectromechanical systems (MEMS) comprising:
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providing a semiconductor-on-insulator substrate comprising a handle layer, a device layer, and an insulating layer disposed between the handle and device layers; fabricating a transistor-based circuit in the device layer; covering the transistor-based circuit with a masking layer; fabricating a MEMS device in the handle layer; fabricating, in the handle layer, a sacrificial layer that immobilizes the MEMS device; and releasing the MEMS device using an etchant to remove the sacrificial layer, wherein the masking layer is resistant to the etchant and the masking layer protects the transistor-based circuit from the etchant. - View Dependent Claims (17, 18, 19, 20, 21, 22)
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23. A method for encapsulating and integrating nano- and/or micro-electromechanical systems (MEMS) comprising:
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providing a semiconductor-on-insulator substrate comprising a handle layer, a device layer, and an insulating layer disposed between the handle and device layers; fabricating a transistor-based circuit in the device layer; fabricating a MEMS device in the device layer; covering the MEMS device with an etch resistant layer; etching the handle layer beneath the MEMS device using the insulating layer as an etch stop; and releasing the MEMS device from the device layer through the backside of the substrate using an etchant, wherein the etch-resistant layer is resistant to the etchant and the etch-resistant layer protects the transistor-based circuit from the etchant, wherein the etch resistant layer extends over the MEMS device on a frontside of the substrate, wherein the etch resistant layer extends through the device layer and contacts the handle layer. - View Dependent Claims (24, 25, 26, 27, 28, 29)
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Specification