Integrated sensor and circuitry and process therefor
AssigneeEvigia Systems, Inc.
InventorNavid Yazdi
Life of this patent
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Abstract
A micromachined sensor and a process for fabrication and vertical integration of a sensor and circuitry at wafer-level. The process entails processing a first wafer to incompletely define a sensing structure in a first surface thereof, processing a second wafer to define circuitry on a surface thereof, bonding the first and second wafers together, and then etching the first wafer to complete the sensing structure, including the release of a member relative to the second wafer. The first wafer is preferably a silicon-on-insulator (SOI) wafer, and the sensing structure preferably includes a member containing conductive and insulator layers of the SOI wafer. Sets of capacitively coupled elements are preferably formed from a first of the conductive layers to define a symmetric capacitive full-bridge structure.
Claims18
A process of forming a micromachined sensor comprising a sensing structure and circuitry electrically coupled to the sensing structure, the process comprising:
- processing a first wafer comprising at least first and second layers, the first wafer being processed to incompletely define the sensing structure in the first layer at a first surface of the first wafer;
- processing a second wafer to define the circuitry on a surface thereof;
- bonding the first and second wafers together so that first portions of the first layer are not bonded to the second wafer and second portions of the first layer are bonded to the second wafer and support the second layer on the second wafer;
- and then
- etching the first wafer to complete the sensing structure by removing first portions of the second layer of the first wafer at a second surface thereof opposite the first surface to define a member that is a movable part of the sensing structure and defined by at least second portions of the second layer, the etching step releasing the member relative to the second wafer while the first portions of the first layer remain physically connected by the second portions of the second layer;
- wherein the step of processing the first wafer comprises forming in the first and second portions of the first layer at least first and second elements spaced apart to define a gap therebetween, and forming in the second portion of the first layer means for supporting the member at oppositely-disposed ends thereof;
- and
- wherein the first and second elements and the supporting means are formed entirely in the first layer of the first wafer, and the member is formed in the first portion of the first layer, the second portion of the second layer, and an insulator layer therebetween.
A process of forming a micromachined sensor comprising a sensing structure and circuitry electrically coupled to the sensing structure, the process comprising:
- processing a first wafer comprising at least first and second layers, the first wafer being processed to incompletely define the sensing structure in the first layer at a first surface of the first wafer;
- processing a second wafer to define the circuitry on a surface thereof;
- bonding the first and second wafers together so that first portions of the first layer are not bonded to the second wafer and second portions of the first layer are bonded to the second wafer and support the second layer on the second wafer;
- and then
- etching the first wafer to complete the sensing structure by removing first portions of the second layer of the first wafer at a second surface thereof opposite the first surface to define a member that is a movable part of the sensing structure and defined by at least second portions of the second layer, the etching step releasing the member relative to the second wafer while the first portions of the first layer remain physically connected by the second portions of the second layer;
- wherein the etching step releases the member by removing portions of a third layer of the first wafer after removing the first portions of the second layer and using the second portions of the second layer as a mask.
A process of forming a micromachined sensor comprising a sensing structure and circuitry electrically coupled to the sensing structure, the process comprising:
- processing a first wafer comprising first and second conductive layers and a buried insulator layer separating the first and second conductive layers, the first wafer being processed to incompletely define the sensing structure in the first conductive layer at a first surface of the first wafer;
- processing a second wafer to define the circuitry on a surface thereof;
- bonding the first and second wafers together so that first portions of the first conductive layer are not bonded to the second wafer and second portions of the first conductive layer are bonded to the second wafer and support the second conductive layer and the buried insulator layer on the second wafer;
- and then
- etching the first wafer to complete the sensing structure by removing first portions of the second conductive layer and the buried insulator layer of the first wafer at a second surface thereof opposite the first surface to define a member that is a movable part of the sensing structure and defined by at least second portions of the second conductive and buried insulator layers, the etching step releasing the member relative to the second wafer while the first portions of the first conductive layer remain physically connected by the second portions of the second conductive and buried insulator layers.
Dependencies are inferred from the claim text.