Pre-bond cavity air bridge
First Claim
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1. A method for forming an air bridge in a bonded wafer comprising the steps offorming a cavity having a surface in a handle wafer;
- covering the surface of the cavity with a dielectric layer;
covering substantially all of a lower surface of a device wafer with an insulating layer to form an enclosed and dielectrically lined cavity;
bonding the insulating layer on the lower surface of a device wafer to the handle wafer;
covering an upper surface of the device layer with a first metal layer lying over the cavity of the handle wafer; and
forming the first metal layer on the upper surface of the device wafer into a metal lead over the cavity of the handle wafer.
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Abstract
A handle wafer has a cavity coated with a dielectric. A device wafer is bonded to the handle wafer. Metal lines, devices or circuits fabricated on device layer overlay the cavity in the handle wafer thus reducing parasitic capacitances to the handle wafer and crosstalk through the handle wafer. This constitutes a rugged air bridge structure capable of being passivated and/or being placed in plastic packages.
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Citations
8 Claims
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1. A method for forming an air bridge in a bonded wafer comprising the steps of
forming a cavity having a surface in a handle wafer; -
covering the surface of the cavity with a dielectric layer; covering substantially all of a lower surface of a device wafer with an insulating layer to form an enclosed and dielectrically lined cavity; bonding the insulating layer on the lower surface of a device wafer to the handle wafer; covering an upper surface of the device layer with a first metal layer lying over the cavity of the handle wafer; and forming the first metal layer on the upper surface of the device wafer into a metal lead over the cavity of the handle wafer. - View Dependent Claims (2, 3, 4, 7)
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5. An air bridge on a bonded wafer comprising:
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a handle wafer with an air bridge cavity having a surface in a surface of the handle wafer; a device wafer with a lower surface substantially entirely covered with an insulating layer, bonded to the handle wafer and covering the air bridge cavity; a metal lead on an upper surface of the device wafer; and a dielectric layer coating the surface of the air bridge cavity whereby the air bridge cavity is enclosed with a dielectric surface. - View Dependent Claims (6, 8)
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Specification