US6060818A
Expired / Lapsed
US
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SBAR structures and method of fabrication of SBAR.FBAR film processing techniques for the manufacturing of SBAR/BAR filters
Assignee: Avago Technologies International Sales Pte Ltd
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Filing: 1998-06-02
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Granted: 2000-05-09
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Expires: 2018-06-02
Abstract
Abstract An acoustical resonator and a method for making the same. A resonator according to the present invention includes a layer of piezoelectric material sandwiched between first and second electrodes. The first electrode includes a conducting sheet having a RMS variation in height of less than 2 μm. The resonator bridges a cavity in a substrate on which the resonator is constructed. The resonator is constructed by creating a cavity in the substrate and filling the same with a sacrificial material that can be rapidly removed from the cavity after the deposition of the various layers making up the resonator. The surface of the filled cavity is polished to provide a RMS variation in height of less than 0.5 μm. The first electrode is deposited on the polished surface to a thickness that assures that the RMS variation in height of the metallic layer is less than 2 μm. The piezoelectric layer is deposited on the first electrode and the second electrode is then deposited on the piezoelectric layer. The sacrificial material is then removed from the cavity by opening vias into the cavity and removing the material through the vias. The preferred sacrificial material is phophor-silica-glass.
Inventors
- 👤 Richard C. Ruby
- 👤 Yogesh Desai
- 👤 Donald R. Bradbury
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 15:30
CPC Classifications
H; H03; H03H; H03H9/00; H03H9/15; H03H9/17; H03H9/171; H03H9/172; H03H9/173; H03H3/00; H03H3/007; H03H3/02; H03H9/02; H03H9/02007; H03H9/02086; H03H9/02133; H03H9/46; H03H9/54; H03H9/58; H03H9/582; H03H9/583; H03H9/585; Y; Y10; Y10T; Y10T29/00; Y10T29/42
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
41 words
An acoustical resonator comprising: a first electrode comprising a conducting sheet having a RMS variation in height of less than 2 μm; a second electrode comprising a conducting sheet; a layer of piezoelectric material sandwiched between said first and second electrodes.
Claim 2
Dependent Claim
41 words
An acoustical resonator comprising: a first electrode comprising a conducting sheet having a RMS variation in height of less than 2 μm; a second electrode comprising a conducting sheet; a layer of piezoelectric material sandwiched between said first and second electrodes.
Claim 3
Dependent Claim
12 words
The acoustical resonator of claim 1 wherein said first electrode comprises molybdenum.
Claim 4
Dependent Claim
14 words
The acoustical resonator of claim 1 wherein said layer of piezoelectric material comprises AlN.
Claim 5
Dependent Claim
23 words
The acoustical resonator of claim 1 further comprising a substrate having a cavity in a surface thereof, said first electrode bridging said cavity.
Claim 6
Dependent Claim
15 words
The acoustical resonator of claim 4 wherein said cavity is less than 30 μm deep.
Claim 7
Dependent Claim
17 words
The acoustical resonator of claim 4 wherein said surface of said substrate comprises an electrically insulating layer.
Claim 8
Independent Claim
98 words
A method for fabricating an acoustical resonator on a substrate having a top surface, said method comprising steps of: generating a depression in said top surface; filling said depression with a sacrificial material, said filled depression having an upper surface level with said top surface of said substrate, said upper surface having a RMS variation in height of less than 0.5 μm; depositing a first electrode on said upper surface; depositing a layer of piezoelectric material on said first electrode; depositing a second electrode on said layer of piezoelectric material; and removing said sacrificial material from said depression.
Claim 9
Independent Claim
98 words
A method for fabricating an acoustical resonator on a substrate having a top surface, said method comprising steps of: generating a depression in said top surface; filling said depression with a sacrificial material, said filled depression having an upper surface level with said top surface of said substrate, said upper surface having a RMS variation in height of less than 0.5 μm; depositing a first electrode on said upper surface; depositing a layer of piezoelectric material on said first electrode; depositing a second electrode on said layer of piezoelectric material; and removing said sacrificial material from said depression.
Claim 10
Dependent Claim
25 words
The method of claim 7 wherein said sacrificial material comprises a material chosen from the group consisting of PSG, BPSG, spin-on-glass, polyvinyl, polypropylene and polystyrene.
Claim 11
Dependent Claim
35 words
The method of claim 7 wherein said step of filling said depression comprises the steps of: depositing a layer of said sacrificial material over said depression; planarizing said deposited layer; and polishing said planarized layer.
Claim 12
Dependent Claim
52 words
The method of claim 9 further comprising the step of providing a layer of an electrically insulating material on the surface of said substrate and depression prior to depositing said layer of sacrificial material, said electrically insulating material preventing a diffusion of elements in said sacrificial material from diffusing into said substrate.
Claim 13
Dependent Claim
11 words
The method of claim 7 wherein said first electrode comprises molybdenum.
Claim 14
Dependent Claim
13 words
The method of claim 7 wherein said layer of piezoelectric material comprises AlN.
Claim 15
Dependent Claim
14 words
The method of claim 7 wherein said depression is less than 30 μm deep.
References Cited (Backward Citations)
US5587620A
Cited
US5873153A
Cited
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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