EP0299870A2 — Method for preparing a superconducting thin film

Claim 1

Independent Claim 75 words

A process for preparing a compound oxide type superconducting thin film including the steps comprising depositing a thin film of compound oxide on a substrate and then subjecting the thin film of compound oxide to heat-treatment in the presence of oxygen gas, improvement in that said heat-treatment is carried out in a same chamber in which the thin film of compound oxide is deposited on the substrate without taking the substrate out of said chamber.

Claim 2

Dependent Claim 75 words

A process for preparing a compound oxide type superconducting thin film including the steps comprising depositing a thin film of compound oxide on a substrate and then subjecting the thin film of compound oxide to heat-treatment in the presence of oxygen gas, improvement in that said heat-treatment is carried out in a same chamber in which the thin film of compound oxide is deposited on the substrate without taking the substrate out of said chamber.

Claim 3

Dependent Claim 71 words

A process set forth in claim 1, characterized in that the heat-treatment include the steps comprising heating the thin film deposited on the substrate at a temperature ranging from 700 to 900 °C for more than 6 minutes, cooling the thin film at a cooling rate of less than 100 °C/min, and then keeping the thin film at a temperature ranging from 300 to 500 °C for more than 6 minutes.

Claim 4

Dependent Claim 23 words

A process set forth in Claim 1 or 2, characterized in that said superconducting thin film is prepared by physical vapour deposition technique.

Claim 5

Dependent Claim 77 words

A process set forth in any one of Claim 1 to 3, characterized in that said superconducting thin film is a thin film of compound oxide composed of at least one element α selected from IIa group of the Periodic Table, at least one element β selected from IIIa group of the Periodic Table, at least one element γ selected from a group comprising Ib, IIb, IIIb, IVa and VIIIa group of the Periodic Table and oxygen.

Claim 6

Dependent Claim 107 words

A process set forth in claim 4, characterized in that said superconducting thin film is a thin film of compound oxide represented by the formula: (α 1-x β x )Cu y O z in which α and β means the same definition as above, x is an atomic ratio of β with respect to (α+β) and has a range of 0.1 ≦ x ≦ 0.9, and y and z are respective atomic ratios with respect to (α 1-x β x ) which is considered to be equal to 1 and each satisfies a range of 0.4 ≦ y ≦ 3.0 and 1 ≦ z ≦ 5 respectively.

Claim 7

Dependent Claim 42 words

A process set forth in Claim 5, characterized in that said element a is Ba and said element β is at least one element selected from a group comprising Y, La, Gd, Dy, Ho, Er, Tm, Yb, Nd, Sm, Eu and Lu.

Claim 8

Dependent Claim 28 words

A process set forth in any one of Claim 4 to 6, characterized in that said superconducting thin film has a perovskite type or quasi-perovskite type crystal structure.

Claim 9

Dependent Claim 44 words

A process set forth in any one of Claim 3 to 7, characterized in that a vapour source used in the physical vapour deposition technique is a sintered mass or powder which is prepared by sintering a powder mixture of Y₂O₃, CuO and BaCuO₂.

Claim 10

Dependent Claim 39 words

A process set forth in any one of Claim 3 to 8, characterized in that the partial pressure of oxygen during the physical vapour deposition is within a range of from 1.0 x 10⁻⁸ to 5.0 x 10⁻² Torr.

Claim 11

Dependent Claim 33 words

A process set forth in any one of Claim 3 to 9, characterized in that said substrate is heated at a temperature ranging from 100 to 1,000 °C during the physical vapour deposition.

Claim 12

Dependent Claim 26 words

A process set forth in any one of Claim 3 to 10, characterized in that that said substrate is a single crystal of MgO or SrTiO₃.

Claim 13

Dependent Claim 31 words

A process set forth in Claim 11, characterized in that said superconducting thin film is deposited on a {001} plane or {110} plane of a single crystal of MgO or SrTiO₃.

Claim 14

Dependent Claim 116 words

A process set forth in any one of Claim 1 to 3, characterized in that said superconducting thin film is a thin film of compound oxide represented by the formula: Θ₄(Φ 1-q , Ca q )mCu n O p+r in which Θ stands for Bi or Tl, Φ stands for Sr when Θ is Bi and stands for Ba when Θ is Tl, m and n are numbers each satisfying ranges of 6 ≦ m ≦ 10 and 4 ≦ n ≦ 8 respectively, p = (6+m+n), q is a number which satisfies a range of 0 < q < 1, and r is a number which satisfies a range of -2 ≦ r ≦ +2.

Claim 15

Dependent Claim 175 words

A process for preparing a superconducting thin film composed of compound oxide including at least one element α selected from IIa group of the Periodic Table, at least one element β selected from IIIa group of the Periodic Table, at least one element γ selected from a group comprising Ib, IIb, IIIb, IVa and VIIIa group of the Periodic Table and oxygen, said process including the steps comprising depositing a thin film of compound oxide on a substrate by physical vapour deposition and then subjecting the thin film of compound oxide to heat-treatment in the presence of oxygen gas, improvement in that, in the stage of said heat-treatment, the thin film deposited on the substrate is heated at a temperature ranging from 700 to 900 °C and under a partial pressure of oxygen ranging from 0.1 to 5 atm for more than 6 minutes, then is cooled down at a cooling rate of less than 100 °C/min, and then is kept at a temperature ranging from 300 to 500 °C for more than 6 minutes.

Claim 16

Dependent Claim 175 words

A process for preparing a superconducting thin film composed of compound oxide including at least one element α selected from IIa group of the Periodic Table, at least one element β selected from IIIa group of the Periodic Table, at least one element γ selected from a group comprising Ib, IIb, IIIb, IVa and VIIIa group of the Periodic Table and oxygen, said process including the steps comprising depositing a thin film of compound oxide on a substrate by physical vapour deposition and then subjecting the thin film of compound oxide to heat-treatment in the presence of oxygen gas, improvement in that, in the stage of said heat-treatment, the thin film deposited on the substrate is heated at a temperature ranging from 700 to 900 °C and under a partial pressure of oxygen ranging from 0.1 to 5 atm for more than 6 minutes, then is cooled down at a cooling rate of less than 100 °C/min, and then is kept at a temperature ranging from 300 to 500 °C for more than 6 minutes.

Claim 17

Dependent Claim 107 words

A process set forth in claim 14, characterized in that said superconducting thin film is a thin film of compound oxide represented by the formula: (α 1-x β x )Cu y O z in which α and β means the same definition as above, x is an atomic ratio of β with respect to (α+β) and has a range of 0.1 ≦ x ≦ 0.9, and y and z are respective atomic ratios with respect to (α 1-x β x ) which is considered to be equal to 1 and each satisfies a range of 0.4 ≦ y ≦ 3.0 and 1 ≦ z ≦ 5 respectively.

Claim 18

Dependent Claim 42 words

A process set forth in Claim 15, characterized in that said element α is Ba and said element β is at least one element selected from a group comprising Y, La, Gd, Dy, Ho, Er, Tm, Yb, Nd, Sm, Eu and Lu.

Claim 19

Dependent Claim 39 words

A process set forth in any one of Claim 14 to 16, characterized in that the partial pressure of oxygen during the physical vapour deposition is within a range of from 1.0 x 10⁻⁸ to 5.0 x 10⁻² Torr.

Claim 20

Dependent Claim 33 words

A process set forth in any one of Claim 14 to 17, characterized in that said substrate is heated at a temperature ranging from 100 to 1,000 °C during the physical vapour deposition.

Claim 21

Dependent Claim 26 words

A process set forth in any one of Claim 14 to 18, characterized in that that said substrate is a single crystal of MgO or SrTiO₃.

Claim 22

Dependent Claim 31 words

A process set forth in Claim 19, characterized in that said superconducting thin film is deposited on a {001} plane or {110} plane of a single crystal of MgO or SrTiO₃.

Method for preparing a superconducting thin film

Abstract

Inventors

Bibliographic Details

Claims Analysis

References Cited (Backward Citations)

USPTO Annuity & Maintenance Windows

Assigned Categories & Tags

Assign Category Tag