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US5358889A
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Formation of ruthenium oxide for integrated circuits
Assignee: Nortel Networks Ltd
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Filing: 1993-04-29
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Granted: 1994-10-25
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Expires: 2013-04-29
Abstract
Abstract A method is provided for forming a conductive layer of ruthenium oxide layer RuO 2 . The RuO 2 layer is formed from a coating of a precursor solution comprising a ruthenium (III) nitrosyl salt,subsequent heat treatment, and annealing at low temperature. The resulting layer of a tetragonal phase of crystalline ruthenium oxide is suitable for formation thereon of a perovskite structure ferroelectric material for applications in ferroelectric non-volatile memory cells. The chloride free process is compatible with processing for submicron device structures for bipolar, CMOS or bipolar CMOS integrated circuits.
Inventors
- 👤 Ismail T. Emesh
- 👤 David R. McDonald
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 17:05
CPC Classifications
C; C23; C23C; C23C18/00; C23C18/02; C23C18/12; C23C18/1204; C23C18/1208; C23C18/1216; C23C18/1225; H; H10; H10D; H10D1/00; H10D1/60; H10D1/68; H10D1/692
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
72 words
A method of forming a conductive layer of ruthenium oxide for an integrated circuit, the method comprising: coating an integrated circuit substrate with a layer of an aqueous solution comprising a water soluble ruthenium (III) nitrosyl salt, a water soluble viscosity modifier, and a volatile organic acid, and subsequently heating the layer to a temperature in the range from 150° C. to 200° C. to form an amorphous phase of ruthenium oxide.
Claim 2
Independent Claim
72 words
A method of forming a conductive layer of ruthenium oxide for an integrated circuit, the method comprising: coating an integrated circuit substrate with a layer of an aqueous solution comprising a water soluble ruthenium (III) nitrosyl salt, a water soluble viscosity modifier, and a volatile organic acid, and subsequently heating the layer to a temperature in the range from 150° C. to 200° C. to form an amorphous phase of ruthenium oxide.
Claim 3
Independent Claim
101 words
A method of forming a conductive layer of ruthenium oxide for an integrated circuit, the method comprising: coating an integrated circuit substrate with a layer of an aqueous solution comprising a water soluble ruthenium (III) nitrosyl salt, a water soluble viscosity modifier, and a volatile organic acid; heating the layer to a temperature in the range from 150° C. to 200° C. to form an amorphous phase of ruthenium oxide; and subsequently annealing the layer at a temperature above 300° C. and below 700° C. for a sufficient time to cause crystallization of the amorphous ruthenium oxide to a tetragonal phase.
Claim 4
Independent Claim
101 words
A method of forming a conductive layer of ruthenium oxide for an integrated circuit, the method comprising: coating an integrated circuit substrate with a layer of an aqueous solution comprising a water soluble ruthenium (III) nitrosyl salt, a water soluble viscosity modifier, and a volatile organic acid; heating the layer to a temperature in the range from 150° C. to 200° C. to form an amorphous phase of ruthenium oxide; and subsequently annealing the layer at a temperature above 300° C. and below 700° C. for a sufficient time to cause crystallization of the amorphous ruthenium oxide to a tetragonal phase.
Claim 5
Dependent Claim
37 words
A method according to claim 2 wherein the ruthenium III nitrosyl salt solution consists of a nitrate salt in dilute nitric acid solution, the viscosity modifier consists of glycerol and the organic acid consists of acetic acid.
Claim 6
Independent Claim
76 words
A method of forming a conductive layer of ruthenium oxide for an integrated circuit comprising: coating an integrated circuit substrate with a layer of an aqueous solution comprising, by weight: 10-80% of a ruthenium (III) nitrosyl salt solution 2-50% of a water soluble viscosity modifier 1-30% of a volatile organic acid; and then heating the layer to a temperature between 150° C. and 400° C. to form a layer of ruthenium oxide on the substrate surface.
Claim 7
Independent Claim
76 words
A method of forming a conductive layer of ruthenium oxide for an integrated circuit comprising: coating an integrated circuit substrate with a layer of an aqueous solution comprising, by weight: 10-80% of a ruthenium (III) nitrosyl salt solution 2-50% of a water soluble viscosity modifier 1-30% of a volatile organic acid; and then heating the layer to a temperature between 150° C. and 400° C. to form a layer of ruthenium oxide on the substrate surface.
Claim 8
Dependent Claim
28 words
A method according to claim 4 comprising repeating the steps of coating with precursor solution and heating to build up a ruthenium oxide layer of a required thickness.
Claim 9
Dependent Claim
38 words
A method according to claim 4 comprising subsequently annealling the amorphous ruthenium oxide layer at between 300° C. and 700° C. to induce crystallization of the layer to form a tetragonal phase of ruthenium oxide (RuO 2 ).
Claim 10
Dependent Claim
27 words
A method according to claim 4 wherein the water soluble viscosity modifier is selected from the group consisting of glycerol, ethylene glycol, polyvinyl alcohol, and polyethylene glycol.
Claim 11
Dependent Claim
27 words
A method according to claim 4 wherein the volatile organic acid is selected from the group consisting of acetic acid, formic acid, propionic acid and lactic acid.
Claim 12
Independent Claim
102 words
A method of forming an integrated circuit capacitor structure on a semiconductor substrate, comprising: forming a first electrode comprising conductive metal oxide; forming a layer of a perovskite ferroelectric material thereon; and forming a second electrode; wherein the step of forming the conductive metal oxide layer comprises coating the substrate with a layer of an aqueous precursor solution comprising a ruthenium (III) nitrosyl salt, and then heat treating the layer at a temperature below 450° C. to form a layer comprising an amorphous ruthenium oxide phase, and subsequently annealing the amorphous ruthenium oxide layer to form a crystalline phase of ruthenium oxide.
Claim 13
Independent Claim
102 words
A method of forming an integrated circuit capacitor structure on a semiconductor substrate, comprising: forming a first electrode comprising conductive metal oxide; forming a layer of a perovskite ferroelectric material thereon; and forming a second electrode; wherein the step of forming the conductive metal oxide layer comprises coating the substrate with a layer of an aqueous precursor solution comprising a ruthenium (III) nitrosyl salt, and then heat treating the layer at a temperature below 450° C. to form a layer comprising an amorphous ruthenium oxide phase, and subsequently annealing the amorphous ruthenium oxide layer to form a crystalline phase of ruthenium oxide.
Claim 14
Dependent Claim
73 words
A method according to claim 9 wherein the aqueous precursor solution comprises, by weight: 10-80% of a ruthenium (III) nitrosyl salt solution 2-50% of a water soluble viscosity modifier 1-30% of a volatile organic acid; and after coating the substrate with a layer of said precursor solution, heat treating the layer comprises heating to a temperature between 200° C. and 400° C. to form the layer of ruthenium oxide on the substrate surface.
Claim 15
Dependent Claim
28 words
A method according to claim 10 comprising repeating the steps of coating with precursor solution and heating to build up a ruthenium oxide layer of a required thickness.
Claim 16
Dependent Claim
46 words
A method according to claim 10 wherein subsequently annealing the amorphous ruthenium oxide layer comprises heating to a temperature between 300° C. and 700° C. for a sufficient time to induce crystallization of the layer to form a tetragonal phase of ruthenium oxide (RuO 2 ).
References Cited (Backward Citations)
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) | 1997-10-24 | 1998-04-25 | 1998-10-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-10-24 | 2002-04-25 | 2002-10-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-10-24 | 2006-04-25 | 2006-10-25 | $7700.00 | Window Closed / Lapsed |