Resonant sensor and method of making same
First Claim
1. A method of fabricating a laminar resonant structure, comprising the steps of:
- (a) preparing a substrate workpiece;
(b) securing a laminar material to said substrate;
(c) cleaning the exposed laminar material surface;
(d) patterning a first resist on the laminar material surface;
(e) descumming the resist;
(f) etching the workpiece to form a resonant structure on the substrate;
(g) cleaning and baking the workpiece;
(h) depositing a piezoelectric layer on the workpiece surface;
(i) patterning and etching the piezoelectric layer to form a piezoelectric slab;
(j) cleaning and rinsing the workpiece;
(k) applying an insulation layer on the workpiece surface and patterning same;
(l) depositing a conductive metallization layer on the workpiece surface and patterning and etching same;
(m) removing the resonant structure from the substrate.
3 Assignments
0 Petitions
Accused Products
Abstract
Microminiature resonant sensor structures are prepared according to micromachining/microfabrication techniques, which structures include thin-film deposits of piezoelectric materials. Such piezoelectric deposits may be excited electrically by including metallized conductive paths during fabrication, or optically. The resonant frequency of the sensor structure is varied by subjecting it to a physical variable, or measurand, such as pressure, temperature, flow rate, etc. Similarly, the resonant frequency of the devices may be detected electrically or optically. The microminiature resonant structures include ribbons and wires, hollow beam and cantilevered hollow beams, and single- and double-ended double beam resonant structures such as tuning forks.
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Citations
22 Claims
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1. A method of fabricating a laminar resonant structure, comprising the steps of:
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(a) preparing a substrate workpiece; (b) securing a laminar material to said substrate; (c) cleaning the exposed laminar material surface; (d) patterning a first resist on the laminar material surface; (e) descumming the resist; (f) etching the workpiece to form a resonant structure on the substrate; (g) cleaning and baking the workpiece; (h) depositing a piezoelectric layer on the workpiece surface; (i) patterning and etching the piezoelectric layer to form a piezoelectric slab; (j) cleaning and rinsing the workpiece; (k) applying an insulation layer on the workpiece surface and patterning same; (l) depositing a conductive metallization layer on the workpiece surface and patterning and etching same; (m) removing the resonant structure from the substrate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of preparing a laminar resonant structure, comprising the steps of:
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(a) preparing a substrate workpiece; (b) depositing a metal layer on said substrate; (c) cleaning the exposed metal layer surface; (d) patterning a first resist on the metal surface; (e) descumming the resist; (f) etching the workpiece to form a resonant structure on the substrate; (g) cleaning and baking the workpiece; (h) depositing a piezoelectric layer on the workpiece surface; (i) patterning and etching the piezoelectric layer to form a piezoelectric slab; (j) cleaning and rinsing the workpiece; (k) applying an insulation layer on the workpiece surface and patterning same; (l) depositing a conductive metallization layer on the insulation layer and patterning and etching same; (m) removing resonant structure from the substrate. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A method of preparing a hollow beam resonant structure comprising the steps of:
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(a) etching at least one trough in the front face of a first substrate area, (b) doping a selected trough area of said first substrate area to a predetermined etch-stop depth, (c) depositing a piezoelectric material in a selected one of said at least one trough area, (d) depositing a resistive insulation current blocking layer between said first substrate area and said piezoelectric material, (e) depositing a metallization layer means for communicating drive and sense signals to said piezoelectric material, (f) etching at least one complementary-image trough in the front face surface of a second substrate area, (g) doping a selected trough area of said second substrate area to a predetermined etch-stop depth, (h) aligning the first and second substrate areas in precise registration with their respective front face substrate surfaces joined, (i) bonding said joined front face substrate surfaces together, and (j) etching sufficient undoped substrate away from the doped substrate region to relieve the doped portion from the remaining substrate material, and leave a relieved, hollow microstructural cantilever beam.
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21. A microfabricated laminar resonant microstructure for use in sensing a measurand, fabricated by the steps of:
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(a) preparing a substrate; (b) releasably securing a laminar material to said substrate; (c) cleaning the exposed laminar material surface; (d) patterning a first resist to outline on the laminar material surface the desired resonant microstructure workpiece; (e) descumming the resist; (f) etching the workpiece to form a resonant microstructure on the substrate; (g) cleaning and baking the workpiece; (h) depositing a piezoelectric layer on the workpiece surface; (i) patterning and etching the piezoelectric layer to form at least one piezoelectric slab on the resonant microstructure; (j) cleaning and rinsing the workpiece; (k) applying an insulation layer on the workpiece surface and patterning same to outline areas for apertures through said insulation layer to the surface of the piezoelectric slab; (l) etching through the insulating layer to the surface of the piezoelectric slab to provide apertures through said insulation layer and access to contact areas thereon; (m) depositing a conductive metallization layer on at least a portion of the workpiece surface and patterning and etching same to form desired electrical contact areas through the insulation apertures to the piezoelectric slab underneath; (n) removing the resonant structure from the substrate.
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22. A microfabricated resonant microstructure for use in sensing a measurand, fabricated by the steps of:
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(a) preparing a substrate; (b) releasably depositing a metallization layer on said substrate; (c) cleaning the exposed metallization layer surface; (d) patterning a first resist to outline on the metallization surface the desired resonant microstructure; (e) descumming the resist; (f) etching the workpiece to form a resonant microstructure on the substrate; (g) cleaning and baking the workpiece; (h) depositing a piezoelectric layer on the workpiece surface; (i) patterning and etching the piezoelectric layer to form at least one piezoelectric slab on the resonant microstructure (j) cleaning and rinsing the workpiece; (k) applying an insulation layer on the workpiece surface and patterning same to outline areas for apertures through said insulation layer to contact areas on the surface of the piezoelectric slab; (l) etching through the insulating layer to the surface of the piezoelectric slab to provide apertures through said insulation layer and access to contact areas thereon; (m) depositing a conductive metallization layer on at least a portion of the workpiece surface and patterning and etching means to form desired electrical contact areas through the insulation aperture to the piezoelectric slab underneath; (n) removing the resonant structure from the substrate.
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Specification