MEMS devices and methods of forming same
First Claim
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1. A method of forming a MEMS device comprising:
- forming an isolation layer atop a substrate;
forming a sacrificial layer atop the isolation layer;
forming a first opening through the sacrificial layer;
bonding a wafer to the sacrificial layer;
forming a second opening extending through the wafer and aligned with the first opening;
filling the first opening and the second opening with a conductor stack;
forming a contact atop the conductor stack;
forming an etch hole through the wafer to expose the sacrificial layer; and
etching at least a portion of the sacrificial layer to form a cavity under a region of the wafer.
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Abstract
The present invention provides a MEMS structure comprising confined sacrificial oxide layer and a bonded Si layer. Polysilicon stack is used to fill aligned oxide openings and MEMS vias on the sacrificial layer and the bonded Si layer respectively. To increase the design flexibility, some conductive polysilicon layer can be further deployed underneath the bonded Si layer to form the functional sensing electrodes or wiring interconnects. The MEMS structure can be further bonded to a metallic layer on top of the Si layer and the polysilicon stack.
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Citations
20 Claims
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1. A method of forming a MEMS device comprising:
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forming an isolation layer atop a substrate; forming a sacrificial layer atop the isolation layer; forming a first opening through the sacrificial layer; bonding a wafer to the sacrificial layer; forming a second opening extending through the wafer and aligned with the first opening; filling the first opening and the second opening with a conductor stack; forming a contact atop the conductor stack; forming an etch hole through the wafer to expose the sacrificial layer; and etching at least a portion of the sacrificial layer to form a cavity under a region of the wafer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of forming a MEMS device, comprising:
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forming an isolation layer on top of a substrate; forming on top of the isolation layer a sacrificial oxide layer having a flat top surface; forming an oxide opening in the sacrificial oxide layer; bonding a silicon wafer layer to the sacrificial oxide layer; opening a MEMS via in the silicon wafer layer aligned with the oxide opening in the sacrificial oxide layer; filling the aligned MEMS via and the oxide opening with conductor material to form a polysilicon stack; forming an etch hole through the silicon wafer layer; and forming a cavity beneath the silicon wafer layer by removing the sacrificial oxide layer under a portion of the silicon wafer layer. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A method of forming a MEMS device, comprising:
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forming an isolation layer on top of a substrate; forming an anchor electrode on the isolation layer; forming on top of the isolation layer and the anchor electrode a sacrificial oxide layer having a flat top surface; forming an oxide opening in the sacrificial oxide layer, reaching the anchor electrode; bonding a silicon wafer layer to the sacrificial oxide layer; thinning the silicon wafer layer; opening a MEMS via in the silicon wafer layer aligned with the oxide opening in the sacrificial oxide layer; filling the aligned MEMS via and the oxide opening with conductor material to form a polysilicon stack in touch with the anchor electrode; forming an etch hole through the silicon wafer layer; and forming a cavity beneath the silicon wafer layer by removing the sacrificial oxide layer under a portion of the silicon wafer layer. - View Dependent Claims (19, 20)
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Specification