US5478610A
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Metalorganic chemical vapor deposition of layered structure oxides
Assignee: Sharp Corp
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Filing: 1994-09-02
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Granted: 1995-12-26
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Expires: 2014-09-02
Abstract
Abstract A method of fabricating high quality layered structure oxide ferroelectric thin films. The deposition process is a chemical vapor deposition process involving chemical reaction between volatile metal organic compounds of various elements comprising the layered structure material to be deposited, with other gases in a reactor, to produce a nonvolatile solid that deposits on a suitably placed substrate such as a conducting, semiconducting, insulating, or complex integrated circuit substrate. The source materials for this process may include organometallic compounds such as alkyls, alkoxides, β-diketonates or metallocenes of each individual element comprising the layered structure material to be deposited and oxygen. Preferably, the reactor in which the deposition is done is either a hot wall or a cold wall reactor and the vapors are introduced into this reactor either through a set of bubblers or through a direct liquid injection system. The ferroelectric films can be used for device applications such as in capacitors, dielectric resonators, heat sensors, transducers, actuators, nonvolatile memories, optical waveguides and displays.
Inventors
- 👤 Seshu B. Desu
- 👤 W. Tao
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 12:59
CPC Classifications
H; H10; H10P; H10P14/00; H10P14/60; H10P14/69; H10P14/692; H10P14/6938; H10P14/69398; C; C23; C23C; C23C16/00; C23C16/22; C23C16/30; C23C16/40; H10D; H10D1/00; H10D1/60; H10D1/68; H10D1/682; H10D1/692; H10P14/63; H10P14/6326; H10P14/6328; H10P14/6334; H10P14/6336; H10P14/6338; H10P14/66; H10P14/668; H10P50/00; H10P50/20; H10P50/28; H10P50/282; H10P50/283; H10P50/285; H10D1/696
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
146 words
A method of depositing ferroelectric layered structure oxide thin films on a substrate by metalorganic chemical vapor deposition, comprising steps of: maintaining said substrate at a reduced pressure in a chemical vapor deposition reactor; heating said substrate in the chemical vapor deposition reactor; vaporizing metalorganic precursors; transporting vapors of said precursors by a carrier gas or an oxidizing agent or both, and/or a diluent gas into said chemical vapor deposition reactor; and reacting the said vapors to form a thin film of the ferroelectric layered structure oxide on the said substrate, wherein the ferroelectric layered structure oxide is at least one of the compounds: A n Bi 3 Ti n+1 RO 3n+9 ABi 2 R 2 O 9 Bi 2n+2 Ti 4-n O 12-n A n+1 Bi 4 Ti n+4 O 15+3n where A=Ca, Pb, Sr, or Ba; and R=Nb or Ta; and n=0 or 1.
Claim 2
Independent Claim
146 words
A method of depositing ferroelectric layered structure oxide thin films on a substrate by metalorganic chemical vapor deposition, comprising steps of: maintaining said substrate at a reduced pressure in a chemical vapor deposition reactor; heating said substrate in the chemical vapor deposition reactor; vaporizing metalorganic precursors; transporting vapors of said precursors by a carrier gas or an oxidizing agent or both, and/or a diluent gas into said chemical vapor deposition reactor; and reacting the said vapors to form a thin film of the ferroelectric layered structure oxide on the said substrate, wherein the ferroelectric layered structure oxide is at least one of the compounds: A n Bi 3 Ti n+1 RO 3n+9 ABi 2 R 2 O 9 Bi 2n+2 Ti 4-n O 12-n A n+1 Bi 4 Ti n+4 O 15+3n where A=Ca, Pb, Sr, or Ba; and R=Nb or Ta; and n=0 or 1.
Claim 3
Dependent Claim
20 words
The method of claim 1 wherein only said substrate is heated and said reactor is maintained at a lower temperature.
Claim 4
Dependent Claim
15 words
The method of claim 1, wherein the ratio of Ta to Nb is approximately 0.4.
Claim 5
Dependent Claim
69 words
The method of claim 1 wherein said precursors are at least one of: alkyls of elements comprising said layered structure oxide film; alkoxides of elements comprising said layered structure oxide film; β-diketonates of elements comprising said layered structure oxide film; metallocenes of elements comprising said layered structure oxide film; or combination of at least two of alkyls, alkoxides, β-diketonates, and metallocenes of elements comprising said layered structure oxide film.
Claim 6
Dependent Claim
40 words
The method of claim 1 wherein said precursors are Ba-tetramethylheptadione or Ba(thd) 2 for a barium-component, Sr-tetramethylheptadione or Sr(thd) 2 for a struontium-component, Bi- tetramethylheptadione or Bi(thd) 3 for a bismuth-component, Ta-ethoxide for a tantalum-component, and Nb-ethoxide for a niobium-component.
Claim 7
Dependent Claim
57 words
The method of claim 1 wherein said substrate is at least one of: semiconductor composed of at least one of Si, SiO 2 -coated Si, or GaAs; a single crystal insulator composed of at least one of sapphire, ZrO 2 , MgO, SrTiO 3 , BaTiO 3 , or PbTiO 3 ; or a complex integrated circuit.
Claim 8
Dependent Claim
83 words
The method of claim 6 wherein said substrate is coated with a conducting material comprising at least one of: a metal electrode including Pt, Al, Au, or Pd; a conducting oxide electrode including MO x (0<x<2) where M is at least one of Ru, Rh, Ir, Os, Re or lanthanum strontium cobaltate; a conducting nitride electrode including TiN or ZrN; and a superconducting oxide including YBa 2 Cu 2 O 7-x or Bi 2 Sr 2 Ca 2 Cu 3 O 10 .
Claim 9
Dependent Claim
18 words
The method of claim 7 where the said substrate and said coating are separated by an adhesion layer.
Claim 10
Dependent Claim
15 words
The method of claim 1 further comprising heating said substrate to at least 450° C.
Claim 11
Dependent Claim
28 words
The method of claim 1 wherein the films are deposited by heating said substrate to at least 450° C. and annealing at temperatures between 200° and 850° C.
Claim 12
Dependent Claim
18 words
The method of claim 1 wherein the reduced pressure is from about 10 -3 Torr to 760 Torr.
Claim 13
Dependent Claim
19 words
The method of claim 1 wherein said precursors are vaporized at temperatures between 60° and 250° C. in bubblers.
Claim 14
Dependent Claim
29 words
The method of claim 1 wherein the said precursors are held as liquids in a solvent and vaporized at temperatures between 60° and 250° C. on a vaporization matrix.
Claim 15
Dependent Claim
36 words
The method of claim 13 wherein said solvent is a 8:2:1 mixture in moles of tetrahydrofuran (C 4 H 8 O), iso-propanol (C 4 H 10 O), and tetraglyme (C 10 H 22 O 5 ).
Claim 16
Dependent Claim
18 words
The method of claim 1 where the oxidizing agent is at least one of oxygen and nitrous oxide.
Claim 17
Dependent Claim
20 words
The method claim 1 wherein said oxidizing flows at between 200 and 2000 sccm into said chemical vapor deposition reactor.
Claim 18
Dependent Claim
20 words
The method of claim 1 where the said carrier gas is at least one of nitrogen and an inert gas.
Claim 19
Dependent Claim
35 words
The method of claim 1 where the said carrier gas and the mixture of the said carrier gas and the source vapors flows at between 1 and 2000 sccm into said chemical vapor deposition reactor.
Claim 20
Dependent Claim
19 words
The method of claim 1 where the diluent gas is at least one of nitrogen and an inert gas.
Claim 21
Dependent Claim
19 words
The method of claim 1 where the reacting of the vapors in the reactor is enhanced by a plasma.
Claim 22
Dependent Claim
19 words
The method of claim 1 where the reacting of the vapors in the reactor is enhanced by a UV-lamp.
Claim 23
Dependent Claim
15 words
The method of claim 1, further comprising manufacturing the deposited film into a ferroelectric device.
Claim 24
Dependent Claim
16 words
The method of claim 1, further comprising manufacturing the deposited film into a nonvolatile memory device.
Claim 25
Dependent Claim
15 words
The method of claim 1, further comprising manufacturing the deposited film into a capacitor device.
Claim 26
Dependent Claim
27 words
The method of claim 1 wherein said ferroelectric material has a composition SrBi 2 (Ta x Nb 2-x )O 9 with x ranging from 0 to 2.
Claim 27
Dependent Claim
12 words
The method of claim 1 wherein the said entire reactor is heated.
References Cited (Backward Citations)
No citation records indexed.
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