US5873154A
Expired / Lapsed
US
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Method for fabricating a resonator having an acoustic mirror
Assignee: Avago Technologies International Sales Pte Ltd
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Filing: 1996-10-17
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Granted: 1999-02-23
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Expires: 2016-10-17
Abstract
Abstract A Thin Film Bulk Acoustic Wave Resonator (FBAR), comprising a top electrode layer, a substrate, an acoustic mirror that is formed atop the substrate, and a piezoelectric layer that is formed between the top electrode layer and the acoustic mirror. The acoustic mirror is comprised of a plurality of stacked layers. One of the stacked layers forms a bottom electrode layer. At least another one of the stacked layers comprises a polymer material. The piezoelectric produces vibrations in response to a voltage being applied between the top electrode and the bottom electrode. The acoustic mirror acoustically isolates these vibrations from the substrate. The polymer material is preferably an electronic grade polymer and has a capability of withstanding a deposition of the piezoelectric layer at an elevated temperature. The layers forming the acoustic mirror which do not comprise the polymer material comprise a high acoustic impedance material such as, by example, tungsten (W). The polymer material can be spun on the substrate during fabrication of the FBAR.
Inventors
- 👤 Markku Antero Ylilammi
- 👤 Meeri Talvilelei Partanen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 10:34
CPC Classifications
H; H03; H03H; H03H9/00; H03H9/15; H03H9/17; H03H9/171; H03H9/172; H03H9/175; H03H3/00; H03H3/007; H03H3/02; Y; Y10; Y10T; Y10T29/00; Y10T29/42
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
133 words
A method for fabricating a Thin Film Bulk Acoustic Wave Resonator (FBAR), comprising the steps of: STEP A1: forming a first layer on a substrate, the first layer being comprised of a polymer; STEP A2: forming a second, lower electrode layer on an upper surface of the first layer, wherein the first and second layers form an acoustic isolator and wherein STEP A1 includes forming the first layer so as to have a thickness which is an odd multiple of one-fourth of an acoustic wavelength, and wherein STEP A2 includes forming the second layer so as to have a thickness which is an odd multiple of one-fourth of the acoustic wavelength; STEP B: forming a piezoelectric layer on the acoustic isolator; and STEP C: forming an upper electrode layer on the piezoelectric layer.
Claim 2
Independent Claim
133 words
A method for fabricating a Thin Film Bulk Acoustic Wave Resonator (FBAR), comprising the steps of: STEP A1: forming a first layer on a substrate, the first layer being comprised of a polymer; STEP A2: forming a second, lower electrode layer on an upper surface of the first layer, wherein the first and second layers form an acoustic isolator and wherein STEP A1 includes forming the first layer so as to have a thickness which is an odd multiple of one-fourth of an acoustic wavelength, and wherein STEP A2 includes forming the second layer so as to have a thickness which is an odd multiple of one-fourth of the acoustic wavelength; STEP B: forming a piezoelectric layer on the acoustic isolator; and STEP C: forming an upper electrode layer on the piezoelectric layer.
Claim 3
Dependent Claim
37 words
A method as set forth in claim 1, wherein STEP B includes a step of depositing a piezoelectric material at an elevated temperature on at least a portion of the acoustic isolator to form the piezoelectric layer.
Claim 4
Dependent Claim
26 words
A method as set forth in claim 1, wherein STEP A1 includes a step of spinning the polymer on the substrate to form the first layer.
Claim 5
Dependent Claim
26 words
A method as set forth in claim 1, wherein the polymer can withstand a temperature reached during the performance of STEP B without being detrimentally effected.
Claim 6
Dependent Claim
22 words
An FBAR as set forth in claim 1, wherein the second, electrode layer comprises a material having a high characteristic acoustic impedance.
Claim 7
Dependent Claim
21 words
A method as set forth in claim 5, wherein the material having the high characteristic acoustic impedance is comprised of tungsten.
Claim 8
Dependent Claim
16 words
A method as set forth in claim 1, wherein the polymer is an electronic grade polymer.
Claim 9
Dependent Claim
13 words
A method as set forth claim 1, wherein the polymer comprises a polyimide.
Claim 10
Dependent Claim
22 words
A method as set forth claim 1, wherein the polymer comprises one of cyclotene, a silicon-based polymer material, and a carbon-based material.
Claim 11
Dependent Claim
30 words
A method as set forth claim 1, wherein STEP A1 includes forming the first layer so as to have a thickness that is a function of a desired operating frequency.
Claim 12
Dependent Claim
18 words
A method as set forth claim 1, wherein the substrate comprises one of glass, silicon, and gallium arsenide.
Claim 13
Dependent Claim
28 words
A method as set forth claim 1, wherein the first layer has an acoustic impedance which is substantially less than an acoustic impedance of the second, electrode layer.
Claim 14
Dependent Claim
21 words
A method as set forth claim 1, wherein the acoustic isolator isolates vibrations produced by said piezoelectric layer from said substrate.
Claim 15
Dependent Claim
29 words
A method as set forth claim 1, wherein the acoustic isolator transforms an acoustic impedance of said substrate from a first acoustic impedance to a second, lesser acoustic impedance.
Claim 16
Independent Claim
142 words
A method for fabricating a Thin Film Bulk Acoustic Wave Resonator (FBAR), comprising the steps of: forming a multi-layered acoustic isolator on a surface of a substrate, wherein a first plurality of layers of the acoustic isolator are comprised of a polymer having a first acoustic impedance, wherein a second plurality of layers of the acoustic isolator have a second acoustic impedance, wherein individual ones of the first plurality of layers and individual ones of the second plurality of layers are alternately disposed within the acoustic isolator, wherein one of the first plurality of layers is disposed on the substrate, and wherein one of second plurality of layers forms a lower electrode layer and is disposed on one of the first plurality of layers; forming a piezoelectric layer on the acoustic isolator; and forming an upper electrode layer on the piezoelectric layer.
Claim 17
Independent Claim
142 words
A method for fabricating a Thin Film Bulk Acoustic Wave Resonator (FBAR), comprising the steps of: forming a multi-layered acoustic isolator on a surface of a substrate, wherein a first plurality of layers of the acoustic isolator are comprised of a polymer having a first acoustic impedance, wherein a second plurality of layers of the acoustic isolator have a second acoustic impedance, wherein individual ones of the first plurality of layers and individual ones of the second plurality of layers are alternately disposed within the acoustic isolator, wherein one of the first plurality of layers is disposed on the substrate, and wherein one of second plurality of layers forms a lower electrode layer and is disposed on one of the first plurality of layers; forming a piezoelectric layer on the acoustic isolator; and forming an upper electrode layer on the piezoelectric layer.
Claim 18
Dependent Claim
20 words
A method as set forth in claim 15, wherein the first acoustic impedance is less than the second acoustic impedance.
Claim 19
Dependent Claim
20 words
A method as set forth in claim 15, wherein at least one of the second plurality of layers comprises tungsten.
Claim 20
Dependent Claim
18 words
A method as set forth in claim 15, wherein the polymer is comprised of an electronic grade polymer.
Claim 21
Dependent Claim
24 words
A method as set forth claim 15, wherein the polymer comprises one of a polyimide, cyclotene, a silicon-based polymer material, and a carbon-based material.
Claim 22
Dependent Claim
21 words
A method as set forth claim 15, wherein the acoustic isolator isolates the substrate from vibrations produced by said piezoelectric layer.
Claim 23
Dependent Claim
29 words
A method as set forth claim 15, wherein the acoustic isolator transforms an acoustic impedance of said substrate from a first acoustic impedance to a second, lesser acoustic impedance.
Claim 24
Dependent Claim
20 words
A method as set forth in claim 15, wherein individual ones of the first plurality of layers are spun on.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 2002-02-22 | 2002-08-24 | 2003-02-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-02-22 | 2006-08-24 | 2007-02-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-02-22 | 2010-08-24 | 2011-02-23 | $7700.00 | Window Closed / Lapsed |