US3795977A
Expired / Lapsed
US
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Methods for fabricating bistable resistors
Assignee: International Business Machines Corp
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Filing: 1971-12-30
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Granted: 1974-03-12
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Expires: 1991-12-30
Abstract
Abstract Methods for providing bistable resistors fabricated from insulators exhibiting a plurality of impedance states, an example of which is a niobium-niobium oxide device. These methods use thermal treatment and chemical reduction of amorphous metal oxides to form an active filament in each device. In one method consumable metal dots are located on the amorphous metal oxide and the oxide is then annealed in an inert gas, preferably having a small percentage of oxygen therein. This causes an oxidationreduction reaction in the oxide regions directly beneath the metal dots. In a second method, the metal oxide layer is covered with a protective insulating mask except in selected portions, and the exposed metal oxide portions are then annealed in a reducing gas atmosphere. In each method, the top electrodes are deposited on the selectively reduced portions of the metal oxide layer and then the devices are electrically formed using only a small voltage (2 or 3 volts).
Inventors
- 👤 M Berkenblit
- 👤 J Cole
- 👤 K Park
- 👤 A Reisman
- 👤 D Herrell
- 👤 T Light
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 23:06
CPC Classifications
G; G11; G11C; G11C13/00; G11C13/0002; G11C13/0007; G11C11/00; G11C11/21; G11C11/34; G11C11/39; G11C13/0021; G11C13/0069; H; H01; H01C; H01C7/00; H01C7/10; H01C7/105; H01C7/108; H10; H10B; H10B63/00; H10B63/80; H10B63/82; H10N; H10N70/00; H10N70/011; H10N70/021; H10N70/028; H10N70/20; H10N70/801; H10N70/821; H10N70/826; H10N70/881; H10N70/883; H10N70/8833; G11C2013/0083; G11C2213/00; G11C2213/30; G11C2213/31
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
13 words
The method of claim 1, where said insulative layer is an oxide layer.
Claim 2
Dependent Claim
16 words
The method of claim 2, where said oxide layer is an oxide of said base electrode.
Claim 3
Dependent Claim
25 words
The method of claim 1, where said electric field is established by applying a voltage of about 2-3 volts between said base and counter electrodes.
Claim 4
Dependent Claim
42 words
The method of claim 1, where said thermal and chemical treatment step includes placing a substance on said insulative layer which will interact with said insulative layer when heat is applied thereto, and applying heat thereto to chemically alter said insulative layer.
Claim 5
Dependent Claim
30 words
The method of claim 5, where said insulative layer is an oxide layer and said substance is a metal which interacts with said oxide layer when heat is applied thereto.
Claim 6
Dependent Claim
29 words
The method of claim 5, where said heating is at a sufficiently low temperature and for a sufficiently low time that said insulative layer remains amorphous during said interaction.
Claim 7
Dependent Claim
25 words
The method of claim 1, where said thermal and chemical treatment step comprises heating said insulative layer in the presence of a chemically reducing gas.
Claim 8
Dependent Claim
27 words
The method of claim 8, where said heat is applied at a sufficiently low temperature and for a sufficiently short time that said insulative layer remains amorphous.
Claim 9
Dependent Claim
13 words
The method of claim 1, where said insulative layer is 50-3000 angstroms thick.
Claim 10
Independent Claim
110 words
A method for making a bistable resistor, comprising the steps of: establishing a base electrode comprising an electrically conductive material, providing an amorphous oxide layer having a given valence state on said base electrode, reducing said oxide layer to alter its valence state which produces an active region therein exhibiting bistable resistance when a small forming voltage is applied thereacross, providing a counter electrode in contact with said active region to provide a device having a base electrode, an oxide layer, and a counter electrode, electrically forming said device by applying a small voltage between said base and counter electrodes to cause said active region to exhibit said bistable resistance.
Claim 11
Dependent Claim
12 words
The method of claim 11, where said voltage is approximately 2-3 volts.
Claim 12
Dependent Claim
24 words
The method of claim 11 where said thermal and chemical treatment step comprises heating said oxide layer in the presence of a reducing substance.
Claim 13
Dependent Claim
25 words
The method of claim 13, where said heating is at a temperature and for a time which maintains said oxide layer as an amorphous layer.
Claim 14
Dependent Claim
12 words
The method of claim 13, where said reducing substance is a gas.
Claim 15
Dependent Claim
49 words
The method of claim 13, where said reducing substance is a solid material which is located on said oxide layer, the amount of said material being sufficiently low that said oxide layer is not shorted between said base and counter electrodes when said device is heated and chemicalLy treated.
Claim 16
Dependent Claim
23 words
The method of claim 15, where said heating step occurs in the presence of an inert gas having trace amounts of oxygen therein.
Claim 17
Dependent Claim
13 words
The method of claim 11, where said oxide layer is 50-3000 angstroms thick.
Claim 18
Dependent Claim
39 words
The method of claim 11, where said base electrode comprises a metal selected from the group consisting essentially of Nb and Ta, and said counter electrode comprises a metal selected from the group consisting essentially of Sb and Bi.
Claim 19
Independent Claim
94 words
A method for making a bistable resistor, comprising the steps of: establishing a base electrode of niobium, providing an amorphous niobium oxide layer having a given valence state on said base electrode, reducing said amorphous layer to alter its valence state which provides an active region therein exhibiting bistable resistance when subjected to a small forming voltage, said oxide layer remaining amorphous during said thermal and chemical treatment, providing a counter electrode in electrical contact with said active region, applying a forming voltage between said base and counter electrodes to provide a bistable resistor.
Claim 20
Dependent Claim
24 words
The method of claim 20, where said counter electrode is comprised of a metal selected form the group consisting essentially of Sb and Bi.
Claim 21
Dependent Claim
17 words
The method of claim 20, where said forming voltage is in the range of approximately 2-3 volts.
Claim 22
Dependent Claim
45 words
The method of claim 20, where said thermal and chemical treatment comprises placing a reducing substance on said niobium oxide layer and then heating said substance and said oxide layer whereby said reducing substance reacts with said oxide layer and is consumed in said reaction.
Claim 23
Dependent Claim
23 words
The method of claim 23, where said heating occurs in the presence of an inert gas stream having trace amounts of oxygen therein.
Claim 24
Dependent Claim
30 words
The method of claim 24, where said trace amounts of oxygen are in the range of 25-75 parts per million and said heating is at a temperature range of 350*-425*C.
Claim 25
Dependent Claim
29 words
The method of claim 20, where said reducing step comprises heating said oxide layer in the presence of a chemically reducing gas atmosphere at a temperature of about 500*C.
Claim 26
Dependent Claim
14 words
The method of claim 20, where said niobium oxide layer is 50-3000 angstroms thick.
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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) | 1977-03-11 | 1977-09-10 | 1978-03-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-11 | 1981-09-10 | 1982-03-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-11 | 1985-09-10 | 1986-03-12 | $7700.00 | Window Closed / Lapsed |