Patent EP0489519A2 successfully refreshed from Google Patents.
EP0489519A2
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EP
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Sol-gel processing of piezoelectric and ferroelectric films
Assignee: Raytheon Co
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Filing: 1991-11-21
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Granted: —
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Expires: 2011-11-21
Abstract
Abstract A method of providing a perovskite film having a general chemical formula of ABO₃ over a substrate includes the steps of providing (42,44,46,48,50,52) a sol-gel solution of composition of A and B using alkoxides in organic salts and depositing (54) the sol-gel solution as a thin film over the substrate . The film is converted into the perovskite film by rapidly heating (56) the thin film. Preferred perovskite materials include lead zirconate titanate. In one embodiment the films are deposited from sol-gel solutions containing lead, zirconium, and titanium and are converted (58) to a lead zirconate titante crystalline material in an atmosphere of oxygen to provide a ferroelectric dielectric having a high remanent polarization. In an alternate embodiment (Fig. 3), the sol-gel solution of lead, zirconium, and titanium is converted (62) to lead zirconate titanate crystalline material in a non-oxidizing atmosphere of an inert gas, nitrogen, or forming gas to provide materials having high dielectric constants and high and substantially linear dielectric constants with respect to applied voltages.
Inventors
- 👤 Steven D. Bernstein
- 👤 Joseph Matthew Wahl
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 22:03
CPC Classifications
H; H10; H10P; H10P14/00; H10P14/60; H10P14/65; H10P14/6516; H10P14/6544; H10N; H10N30/00; H10N30/01; H10N30/07; H10N30/074; H10N30/077; H10N30/078; H10N30/80; H10N30/85; H10N30/853; H10N30/8548; H10N30/8554; H10D; H10D1/00; H10D1/60; H10D1/68; H10D1/682; H10P14/63; H10P14/6326; H10P14/6328; H10P14/6334; H10P14/6342; H10P14/69; H10P14/692; H10P14/6938; H10P14/69398
Claims Analysis
Total Claims: 36
Claim 1
Independent Claim
53 words
A method of providing a perovskite material having crystal structure over a substrate comprises the steps of: providing a combination of precursors of the perovskite materials; depositing said precursors over the substrate to provide a film having a thickness; and rapidly heating said film to convert said film into the perovskite crystalline material.
Claim 2
Dependent Claim
29 words
The method as recited in Claim 1 wherein the heating step occurs by disposing the substrate having the film into a furnace disposed at the desired crystalline forming temperature.
Claim 3
Dependent Claim
41 words
The method as recited in Claim 1 wherein the rapidly heating step comprises the step of rapidly thermal processing the substrate by exposing the substrate to a sudden increase in temperature at the rate of approximately 1°C to 200°C per second.
Claim 4
Dependent Claim
18 words
The method, as recited in Claim 1, wherein the step of rapidly heating occurs in an oxidizing atmosphere.
Claim 5
Dependent Claim
33 words
The method, as recited in Claim 4, wherein the heating step in the oxidizing atmosphere occurs by disposing the substrate having the film into a furnace disposed at the desired crystalline forming temperature.
Claim 6
Dependent Claim
45 words
The method, as recited in Claim 4, wherein the rapidly heating step in the oxidizing atmosphere comprises the step of rapidly thermally processing the substrate by exposing the substrate to a sudden increase in temperature at the rate of approximately 6°C to 200°C per second.
Claim 7
Dependent Claim
17 words
The method, as recited in Claim 1, wherein the rapidly heating step occurs in an inert atmosphere.
Claim 8
Dependent Claim
34 words
The method, as recited in Claim 7, wherein the inert atmosphere is selected from the group consisting of nitrogen, an inert gas, or a forming gas comprising hydrogen and an inert gas, or argon.
Claim 9
Dependent Claim
29 words
The method, as recited in Claim 7, wherein said heating step occurs by disposing the substrate having the film into a furnace disposed at the desired crystalline forming temperature.
Claim 10
Dependent Claim
41 words
The method, as recited in Claim 7, wherein the rapidly heating step comprises the step of rapidly thermally processing the substrate by exposing the substrate to a sudden increase in temperature at the rate of approximately 6°C to 200°C per second.
Claim 11
Independent Claim
65 words
A method of providing a lead zirconate titanate film over a substrate comprises the steps of: providing in a solution a lead salt, a zirconium alkoxide, and a titanium alkoxide in a predetermined composition ratio; depositing said solution over the substrate to provide a film having a desired thickness; and rapidly heating said film to convert said film into the lead zirconate titanate crystalline material.
Claim 12
Dependent Claim
28 words
The method, as recited in Claim 11, wherein the lead salt is lead acetate trihydrate, the zirconium alkoxide is zirconium propoxide, and the titanium alkoxide is titanium isopropoxide.
Claim 13
Dependent Claim
33 words
The method, as recited in Claim 12, wherein the step of providing the solution further comprises the step of dehydrating the lead acetate trihydrate after dissolving the lead acetate trihydrate in acetic acid.
Claim 14
Dependent Claim
40 words
The method, as recited in Claim 13, wherein the step of providing the solution further comprises the step of controlling the viscosity of the solution by introducing deionized water in a ratio of 2.0-1.0 parts solution to 1 part water.
Claim 15
Dependent Claim
41 words
The method, as recited in Claim 14, wherein the step of rapidly heating the film comprises the step of introducing the substrate having the film into a furnace disposed at the desired crystalline temperature in the range of 400°C to 650°C.
Claim 16
Dependent Claim
34 words
The method, as recited in Claim 15, wherein said furnace is disposed at a temperature in the range of 500°C to less than 600°C for a period of time of less than 40 minutes.
Claim 17
Dependent Claim
19 words
The method, as recited in Claim 14, wherein said furnace has flowing therethrough an atmosphere comprised principally of oxygen.
Claim 18
Dependent Claim
33 words
The method, as recited in Claim 17, wherein said furnace has flowing therethrough an non-oxidizing atmosphere having a gas selected from the group consisting of nitrogen, argon, inert gas, helium, or forming gas.
Claim 19
Dependent Claim
40 words
The method, as recited in Claim 14, wherein the rapidly heating step comprises the step of rapidly thermally processing the substrate to expose the substrate to a sudden increase of temperature in the range of 6°C to 200°C per second.
Claim 20
Dependent Claim
19 words
The method, as recited in Claim 18, wherein said heating step occurs in an atmosphere comprised substantially of oxygen.
Claim 21
Dependent Claim
33 words
The method, as recited in Claim 18, wherein said heating step occurs in a non-oxidizing atmosphere having a gas selected from the group consisting of nitrogen, argon, helium, inert gas, and forming gas.
Claim 22
Independent Claim
115 words
A method of providing a lead zirconate titanate film over a substrate comprising the steps of: providing in a solution a composition of a lead salt, a zirconium alkoxide, and a titanium alkoxide in a predetermined composition ratio; depositing said solution over the substrate to provide a film of a desired thickness; stabilizing the film by subjecting the coated substrate to a localized heat source to cause portions of the film adjacent to said source to initially stabilize while portions of the film removed from said source are initially unstabilized thereby permitting organics to be driven off through the film; and heating said film to convert said film into the lead zirconate titanate crystalline material.
Claim 23
Dependent Claim
28 words
The method, as recited in Claim 22, wherein the lead salt is lead acetate trihydrate, the zirconium alkoxide is zirconium propoxide, and the titanium alkoxide is titanium isopropoxide.
Claim 24
Dependent Claim
33 words
The method, as recited in Claim 23, wherein the step of providing the solution further comprises the step of dehydrating the lead acetate trihydrate after dissolving the lead acetate trihydrate in acetic acid.
Claim 25
Dependent Claim
43 words
The method, as recited in Claim 24, wherein the step of providing the solution further comprises the step of controlling the viscosity of the solution by introducing deionized water in a ratio of 2.0 to 1.0 parts PZT solution to 1 part water.
Claim 26
Dependent Claim
41 words
The method, as recited in Claim 25, wherein the step of rapidly heating the film comprises the step of introducing the substrate having the film into a furnace disposed at the desired crystalline temperature in the range of 400°C to 650°C.
Claim 27
Dependent Claim
34 words
The method, as recited in Claim 25, wherein said furnace is disposed at a temperature in the range of 500°C to less than 600°C for a period of time of less than 40 minutes.
Claim 28
Dependent Claim
19 words
The method, as recited in Claim 25, wherein said furnace has flowing therethrough an atmosphere comprised principally of oxygen.
Claim 29
Dependent Claim
34 words
The method, as recited in Claim 26, wherein said furnace has flowing therethrough an non-oxidizing atmosphere having a gas selected from the group consisting of nitrogen, an argon helium, inert gas, or forming gas.
Claim 30
Dependent Claim
40 words
The method, as recited in Claim 22, wherein the rapidly heating step comprises the step of rapidly thermally processing the substrate to expose the substrate to a sudden increase of temperature in the range of 6°C to 200°C per second.
Claim 31
Dependent Claim
19 words
The method, as recited in Claim 28, wherein said heating step occurs in an atmosphere comprised substantially of oxygen.
Claim 32
Dependent Claim
33 words
A layer of lead zirconate titanate, a sample of said layer having a remanent polarization in the range of 6.0µC/cm² to 35µC/cm² and said sample having a thickness of less than about 3,000Å.
Claim 33
Dependent Claim
33 words
A layer of lead zirconate titanate, a sample of said layer having a thickness of less than about 3,000Å and a coercive voltage in a range of less than 0.5 to 2.0 volts.
Claim 34
Dependent Claim
25 words
A layer of lead zirconate titanate having a remanent polarization greater than about 7.0µC/cm² and a coercive voltage less than about 0.5 to 2.0 volts.
Claim 35
Dependent Claim
26 words
A layer of lead zirconate titanate having a substantially linear dielectric constant with respect to applied voltage in the range of at least 30 to 900.
Claim 36
Dependent Claim
28 words
The layer of lead zirconate, as recited in Claim 35, wherein said layer is disposed over a metal electrode and said metal electrode disposed over an integrated circuit.
References Cited (Backward Citations)
No citation records indexed.
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