Method for constructing an isolate microelectromechanical system (MEMS) device using surface fabrication techniques
First Claim
1. A method of constructing a MEMS device having a first stationary conductive member separated from a second movable conductive member by a variable size gap, the method using exclusively surface fabrication techniques and comprising:
- (a) providing a substrate;
(b) depositing sacrificial material onto the substrate to form a sacrificial layer;
(c) depositing insulating material onto the sacrificial layer to form an insulating layer having at least a portion that is separated from the substrate by the sacrificial layer;
(d) after step (c), depositing conductive material onto the insulating layer to form a conductive layer;
(e) etching through a portion of the conductive layer to the insulating layer to form the first and second adjacent conductive structures separated by a variable size gap;
(f) etching through a portion of the insulating layer around the second conductive structure to provide a base for the second conductive structure; and
(g) etching through at least a portion of the sacrificial layer to release the base and second conductive structure from the substrate, wherein the second conductive structure is movable with respect to the first conductive structure.
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Abstract
A method for fabricating an electrically isolated MEMS device is provided that uses surface fabrication techniques to form a conductive stationary MEMS element, and a movable MEMS element spaced apart from the conductive stationary MEMS element. The movable element includes a nonconductive base which provides for electrical isolation between a plurality of conductive members extending from the base. Modifications to the basic process permit the incorporation of a wafer-level cap which provides mechanical protection to the movable portions of the device.
95 Citations
29 Claims
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1. A method of constructing a MEMS device having a first stationary conductive member separated from a second movable conductive member by a variable size gap, the method using exclusively surface fabrication techniques and comprising:
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(a) providing a substrate;
(b) depositing sacrificial material onto the substrate to form a sacrificial layer;
(c) depositing insulating material onto the sacrificial layer to form an insulating layer having at least a portion that is separated from the substrate by the sacrificial layer;
(d) after step (c), depositing conductive material onto the insulating layer to form a conductive layer;
(e) etching through a portion of the conductive layer to the insulating layer to form the first and second adjacent conductive structures separated by a variable size gap;
(f) etching through a portion of the insulating layer around the second conductive structure to provide a base for the second conductive structure; and
(g) etching through at least a portion of the sacrificial layer to release the base and second conductive structure from the substrate, wherein the second conductive structure is movable with respect to the first conductive structure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 26, 27)
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19. A method for fabricating an encapsulated MEMS device disposed in an ambient environment having a first stationary conductive member separated from a second movable conductive member by a variable size gap, the method using exclusively surface fabrication techniques and comprising:
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(a) depositing conductive trace material and patterning it so that it remains on the outer ends of a substrate to form first and second traces defining upper surfaces;
(b) depositing sacrificial material onto the substrate and patterning it so that it remains between the traces to form a sacrificial layer;
(c) depositing insulating material onto the sacrificial material to form an insulating layer such that the sacrificial layer is disposed between the substrate and the insulating layer, wherein the sacrificial material and insulating material are patterned to create voids therebetween that are aligned with the conductive trace material;
(d) depositing additional trace material so as to cover the upper surfaces and fill the voids followed by planarizing the surface so as to form inner and outer trace members that extend into the ambient environment, wherein insulating material is disposed between the inner and outer trace members;
(e) forming the stationary conductive member in electrical communication with the inner trace member;
(f) etching through a portion of the insulating layer; and
forming the movable conductive member separated by the stationary conductive member by a variable size gap.- View Dependent Claims (20, 21, 22, 23, 24, 25, 28, 29)
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Specification