Patent US2889685A successfully refreshed from Google Patents.
Patent US5853601A successfully refreshed from Google Patents.
US5853601A
Expired / Lapsed
US
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Top-via etch technique for forming dielectric membranes
Assignee: Northrop Grumman Systems Corp
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Filing: 1997-04-03
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Granted: 1998-12-29
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Expires: 2017-04-03
Abstract
Abstract A top-via etch technique for forming dielectric membranes for thin film devices, the dielectric membrane being deposited on the upper planar surface of the substrate. After the thin film device is formed on the dielectric membrane, a photoresist etch mask is deposited on the entire upper planar surface of the substrate, including the thin film structure. Vias are formed through the dielectric membrane and the protective photoresist etch mask to expose the upper planar surface of the substrate along opposite first and second ends of the thin film device. The upper planar surface of the substrate is isotropically etched using a reactive ion etching technique for example, to form air gaps beneath the dielectric membrane. The etching process may be carried out in etch segments of predetermined intervals, each followed by a cool down period of a prescribed interval.
Inventors
- 👤 Silaipillayarputhur V. Krishaswamy
- 👤 William F. Valek
- 👤 Thomas M. Valko
- 👤 Curtis E. Milton, Jr.
- 👤 Joel F. Rosenbaum
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 15:36
CPC Classifications
H; H03; H03H; H03H3/00; H03H3/007; H03H3/02; H03H9/00; H03H9/15; H03H9/17; H03H9/171; H03H9/172
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
123 words
A method of fabricating a film bulk acoustic resonator comprising the steps of: a) depositing a membrane layer on an upper planar surface of a substrate; b) forming a film bulk acoustic resonator on the membrane layer; c) depositing a photoresist etch mask on the membrane layer and the film bulk acoustic resonator; d) opening respective first and second vias through the membrane layer and the photoresist etch mask at respective first and second ends of the film bulk acoustic resonator to expose the substrate; e) isotropically etching the substrate through the first and second vias to form air gaps under the membrane layer along the first and second ends of the film bulk acoustic resonator; and f) removing the photoresist etch mask.
Claim 2
Independent Claim
123 words
A method of fabricating a film bulk acoustic resonator comprising the steps of: a) depositing a membrane layer on an upper planar surface of a substrate; b) forming a film bulk acoustic resonator on the membrane layer; c) depositing a photoresist etch mask on the membrane layer and the film bulk acoustic resonator; d) opening respective first and second vias through the membrane layer and the photoresist etch mask at respective first and second ends of the film bulk acoustic resonator to expose the substrate; e) isotropically etching the substrate through the first and second vias to form air gaps under the membrane layer along the first and second ends of the film bulk acoustic resonator; and f) removing the photoresist etch mask.
Claim 3
Dependent Claim
25 words
The method of fabricating a film bulk acoustic resonator of claim 1, wherein said step e) comprises etching the substrate using a reactive ion etch.
Claim 4
Dependent Claim
44 words
The method of fabricating a film bulk acoustic resonator of claim 2, wherein said step e) comprises etching the substrate in thirty minute etch intervals, each etch interval being followed by a ten minute cool down interval, to obtain air gaps of desired depth.
Claim 5
Dependent Claim
26 words
The method of fabricating a film bulk acoustic resonator of claim 3, wherein said step e) further comprises subjecting the etched substrate to an ash treatment.
Claim 6
Dependent Claim
23 words
The method of fabricating a film bulk acoustic resonator of claim 2, wherein said step e) comprises using SF 6 as reactive gas.
Claim 7
Dependent Claim
45 words
The method of fabricating a film bulk acoustic resonator of claim 1, wherein said step b) comprises: b1) depositing a first electrode on the membrane layer; b2) depositing a piezoelectric layer on the first electrode; and b3) depositing a second electrode on the piezoelectric layer.
Claim 8
Dependent Claim
23 words
The method of fabricating a film bulk acoustic resonator of claim 6, wherein said step b2) comprises depositing AlN as the piezoelectric layer.
Claim 9
Dependent Claim
23 words
The method of fabricating a film bulk acoustic resonator of claim 6, wherein said step b2) comprises depositing ZnO as the piezoelectric layer.
Claim 10
Dependent Claim
51 words
The method of fabricating a film bulk acoustic resonator of claim 1, wherein the substrate is Si and said step a) comprises depositing a first submembrane of SiO 2 on the upper planar surface of the substrate and a second submembrane of ZnO on the first submembrane as the membrane layer.
Claim 11
Dependent Claim
28 words
The method of fabricating a film bulk acoustic resonator of claim 9, wherein the first submembrane is 1 micron thick and the second submembrane is 0.5 micron thick.
Claim 12
Dependent Claim
60 words
The method of fabricating a film bulk acoustic resonator of claim 1, wherein the substrate is Si and said step a) comprises depositing a first submembrane of SiO 2 on the upper planar surface of the substrate, a second submembrane of CrAu on the first submembrane and a third submembrane of ZnO on the second submembrane as the membrane layer.
Claim 13
Dependent Claim
35 words
The method of fabricating a film bulk acoustic resonator of claim 11, wherein the first submembrane is 1 micron thick, the second submembrane is 0.1 micron thick and the third submembrane is 1.5 microns thick.
Claim 14
Dependent Claim
29 words
The method of fabricating a film bulk acoustic resonator of claim 1, wherein the substrate is Si and said step a) comprises depositing SiO 2 as the membrane layer.
Claim 15
Independent Claim
117 words
A method of forming air gaps under a dielectric membrane, the dielectric membrane being deposited on an upper planar surface of a substrate and having a thin film device integrated thereon, the method comprising the steps of: a) depositing a photoresist layer on the dielectric membrane and the thin film device; b) forming respective first and second vias through the dielectric membrane and the photoresist layer at respective first and second ends of the thin film device to expose the substrate; c) isotropically etching the substrate through the first and second vias to form air gaps under the dielectric membrane along the first and second ends of the thin film device; and d) removing the photoresist layer.
Claim 16
Independent Claim
117 words
A method of forming air gaps under a dielectric membrane, the dielectric membrane being deposited on an upper planar surface of a substrate and having a thin film device integrated thereon, the method comprising the steps of: a) depositing a photoresist layer on the dielectric membrane and the thin film device; b) forming respective first and second vias through the dielectric membrane and the photoresist layer at respective first and second ends of the thin film device to expose the substrate; c) isotropically etching the substrate through the first and second vias to form air gaps under the dielectric membrane along the first and second ends of the thin film device; and d) removing the photoresist layer.
Claim 17
Dependent Claim
24 words
The method of forming air gaps under a dielectric membrane of claim 14, wherein the thin film device is a film bulk acoustic resonator.
Claim 18
Dependent Claim
49 words
The method of forming air gaps under a dielectric membrane of claim 14, wherein the substrate is Si and the dielectric membrane is deposited as a first submembrane of SiO 2 on the upper planar surface of the substrate and a second submembrane of ZnO on the first submembrane.
Claim 19
Dependent Claim
58 words
The method of forming air gaps under a dielectric membrane of claim 14, wherein the substrate is Si and the dielectric membrane is deposited as a first submembrane of SiO 2 on the upper planar surface of the substrate, a second submembrane of CrAu on the first submembrane and a third submembrane of ZnO on the second submembrane.
Claim 20
Dependent Claim
38 words
The method of forming air gaps under a dielectric membrane of claim 14, wherein the substrate is Si and the dielectric membrane is deposited on the upper planar surface of the substrate as an SiO 2 dielectric membrane.
Claim 21
Dependent Claim
26 words
The method of forming air gaps under a dielectric membrane of claim 14, wherein said step c) comprises etching the substrate using a reactive ion etch.
Claim 22
Dependent Claim
45 words
The method of forming air gaps under a dielectric membrane of claim 14, wherein said step c) comprises etching the substrate in thirty minute etch intervals, each etch interval being followed by a ten minute cool down interval, to obtain air gaps of desired depth.
Claim 23
Dependent Claim
38 words
The method of forming air gaps under a dielectric membrane of claim 14, wherein said step a) comprises forming a protective skin of photoresist material having enhanced masking ability on the dielectric membrane and the thin film device.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-12-28 | 2002-06-29 | 2002-12-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-12-28 | 2006-06-29 | 2006-12-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-12-28 | 2010-06-29 | 2010-12-29 | $7700.00 | Window Closed / Lapsed |