Patent US4895812A successfully refreshed from Google Patents.
US4895812A
Expired / Lapsed
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Method of making ohmic contact to ferroelectric semiconductors
Assignee: Verizon Laboratories Inc
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Filing: 1988-12-14
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Granted: 1990-01-23
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Expires: 2008-12-14
Abstract
Abstract A layer of chemically compatible conductive material is applied to ferroelectric semiconductor material having a permanent polarization below its Curie temperature. The materials are heated to a temperature above the Curie temperature of the ferroelectric semiconductor material and allowed to cool. The result is a low resistance contact. The ferroelectric semiconductive material may be a layer on a non ferroelectric semiconductor material with a matching work function or matching dopant levels.
Inventors
- 👤 Da Y. Wang
- 👤 Daniel T. Kennedy
- 👤 Burton W. MacAllister, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 12:18
CPC Classifications
H; H10; H10N; H10N30/00; H10N30/01; H10N30/06; Y; Y10; Y10S; Y10S148/00; Y10S148/093; Y10S148/094
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
104 words
A method of fabricating an ohmic contact to a semiconducting ferroelectric material comprising the steps of: providing a semiconducting ferroelectric material having a permanent polarization below the Curie temperature of the ferroelectric material; depositing a layer of chemically compatible electrically conductive material to a surface of said ferroelectric material; heating the ferroelectric material and layer of electrically conductive material to a temperature about the Curie temperature of the ferroelectric material and lower then what would cause chemical reactions or physical degradation of the materials; and allowing said ferroelectric material and layer of conductive material to cool below the Curie temperature of said ferroelectric material.
Claim 2
Independent Claim
104 words
A method of fabricating an ohmic contact to a semiconducting ferroelectric material comprising the steps of: providing a semiconducting ferroelectric material having a permanent polarization below the Curie temperature of the ferroelectric material; depositing a layer of chemically compatible electrically conductive material to a surface of said ferroelectric material; heating the ferroelectric material and layer of electrically conductive material to a temperature about the Curie temperature of the ferroelectric material and lower then what would cause chemical reactions or physical degradation of the materials; and allowing said ferroelectric material and layer of conductive material to cool below the Curie temperature of said ferroelectric material.
Claim 3
Dependent Claim
20 words
The method of claim 1 wherein said semiconductor ferroelectric material is barium titanate doped with one or more alio-valent dopants.
Claim 4
Dependent Claim
28 words
The method of claim 2 wherein said alio-valent dopant is selected from the group consisting of Y, Sb, Sc, V, W, Cr, Ni, Rh, Ru, and combinations thereof.
Claim 5
Dependent Claim
29 words
The method of claim 3 wherein the semiconductor ferroelectic material also includes one or more dopants selected from the group consisting of Ca, Zr, Sn, Pb, Hf, and Sn.
Claim 6
Dependent Claim
31 words
The method of claim 4 wherein said semiconductor ferroelectric material is barium titanate doped with 0.3 m/o Y,16 m/o Ca, and 3.5 m/o Sn and said Curie temperature is 120° C.
Claim 7
Dependent Claim
11 words
The method of claim 1 wherein said conductive material is Au.
Claim 8
Dependent Claim
13 words
The method of claim 6 wherein said Au is deposited by DC sputtering.
Claim 9
Dependent Claim
26 words
The method of claim 1 wherein said conductive material is selected from the group consisting of metals, metal alloys, conductive ceramics, conductive polymers, and combinations thereof.
Claim 10
Independent Claim
120 words
A method of fabricating an ohmic contact comprising the steps of: providing a nonferroelectric semiconducting material having a first work function; applying a layer of a semiconductor ferroelectric material having a permanent polarization below the Curie temperature of the ferroelectric material and having a second work function matching the first work function; depositing a layer of chemically compatible electrically conductive material to said layer of ferroelectric material; heating said layers of ferroelectric material and electrically conductive material to a temperature above the Curie temperature of the ferroelectric material and lower than what would cause chemical reactions or physical degradation of the materials; and allowing said ferroelectric material and conductive material to cool below the Curie temperature of said ferroelectric material.
Claim 11
Independent Claim
120 words
A method of fabricating an ohmic contact comprising the steps of: providing a nonferroelectric semiconducting material having a first work function; applying a layer of a semiconductor ferroelectric material having a permanent polarization below the Curie temperature of the ferroelectric material and having a second work function matching the first work function; depositing a layer of chemically compatible electrically conductive material to said layer of ferroelectric material; heating said layers of ferroelectric material and electrically conductive material to a temperature above the Curie temperature of the ferroelectric material and lower than what would cause chemical reactions or physical degradation of the materials; and allowing said ferroelectric material and conductive material to cool below the Curie temperature of said ferroelectric material.
Claim 12
Dependent Claim
23 words
The method of claim 9 wherein said semiconductor ferroelectric material is barium titanate doped with a percentage of one or more alio-valent dopants.
Claim 13
Dependent Claim
34 words
The method of claim 10 wherein said alio-valent dopant is selected from the group consisting of Y, Sb, any element of the lanthanide group, Sc, V, W, Cr, Ni, Rh, Ru, and combinations thereof.
Claim 14
Dependent Claim
32 words
The method of claim 11 wherein the semiconductor ferroelectric material also includes a percentage of one or more dopants selected from the group consisting of Ca, Zr, Sn, Pb, Hf, and Sn.
Claim 15
Independent Claim
134 words
A method of fabricating an ohmic contact comprising the steps of: providing a nonferroelectric semiconducting material having a first dopant level; applying a layer of a semiconductor ferroelectric material having a permanent polarization below the Curie temperature of the ferroelectric material and having a second dopant level, said first and second dopant levels selected to minimize any electrical barrier at the junction of the semiconducting materials; depositing a layer of chemically compatible electrically conductive material to said layer of ferroelectric material; heating said layers of ferroelectric material and electrically conduction material to a temperature above the Curie temperature of the ferroelectric material and lower than what would cause chemical reactions or physical degradation of the materials; and allowing said ferroelectric material and conductive material to cool below the Curie temperature of said ferroelectric material.
Claim 16
Independent Claim
134 words
A method of fabricating an ohmic contact comprising the steps of: providing a nonferroelectric semiconducting material having a first dopant level; applying a layer of a semiconductor ferroelectric material having a permanent polarization below the Curie temperature of the ferroelectric material and having a second dopant level, said first and second dopant levels selected to minimize any electrical barrier at the junction of the semiconducting materials; depositing a layer of chemically compatible electrically conductive material to said layer of ferroelectric material; heating said layers of ferroelectric material and electrically conduction material to a temperature above the Curie temperature of the ferroelectric material and lower than what would cause chemical reactions or physical degradation of the materials; and allowing said ferroelectric material and conductive material to cool below the Curie temperature of said ferroelectric material.
Claim 17
Dependent Claim
20 words
The method of claim 13 wherein said semiconductor ferroelectric material is barium titanate doped with one or more alio-valent dopants.
Claim 18
Dependent Claim
28 words
The method of claim 14 wherein said alio-valent dopant is selected from the group consisting of Y, Sb, Sc, V, W, Cr, Ni, Rh, Ru, and combinations thereof.
Claim 19
Dependent Claim
29 words
The method of claim 15 wherein the semiconductor ferroelectric material also includes one or more dopants selected from the group consisting of Ca, Zr, Sn, Pb, Hf, and Sn.
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) | 1993-01-22 | 1993-07-24 | 1994-01-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-01-22 | 1997-07-24 | 1998-01-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-01-22 | 2001-07-24 | 2002-01-23 | $7700.00 | Window Closed / Lapsed |