EP0540993A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Structure and fabrication of high transconductance MOS field effect transistor using a buffer layer/ferroelectric/buffer layer stack as the gate dielectric
Assignee: Ramtron International Corp
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Filing: 1992-10-28
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Granted: —
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Expires: 2012-10-28
Abstract
Abstract A field effect transistor is formed with its gate electrode (50) separated from the substrate (10) by a dielectric stack formed by a buffer layer (20), a layer of ferroelectric material (30), and a second buffer layer (40). The gate electrode (50) is directly over the second buffer layer (40). Source and drain regions (60, 70) are located in the substrate (10), and an insulating layer (80) and metalization layer (100) can be employed for contacts. A method for forming the same is also disclosed.
Inventors
- 👤 George Argos, Jr.
- 👤 Thottam S. Kalkur
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-28 19:05
CPC Classifications
H; H10; H10D; H10D30/00; H10D30/60; H10D30/701
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
51 words
A dielectric stack for use in a field effect transistor characterized by substrate (10), a first buffer layer (20) located over said substrate (10), a layer of ferroelectric material (30) located over said first buffer layer (20), and a second buffer layer (40) located over said layer of ferroelectric material (30).
Claim 2
Dependent Claim
40 words
The stack of Claim 1 further characterized by said buffer layers (20, 40) being comprised of a compound selected from the group comprising ZrO₂, La₂O₃, TiO₂, SiO₂, Bi₂O₃, Nb₂O₅, ThO₂, HfO₂, Ta₂O₅, SnO₂, CeO₃, Y₂O₃, Al₂O₃, MgO₂, Si₃N₄ and MgF₂.
Claim 3
Dependent Claim
27 words
The stack of Claim 1 further characterized by said ferroelectric material being Pb(Zr x Ti 1-x )O₂ wherein x is in the range of 0 to 1.0.
Claim 4
Dependent Claim
24 words
The stack of Claim 1 further characterized by said buffer layers (20, 40) and said layer of ferroelectric material (30) having coincident lateral edges.
Claim 5
Dependent Claim
68 words
A field effect transistor characterized by a substrate (10), a first buffer layer (20) located over said substrate (10), a layer of ferroelectric material (30) located over said first buffer layer (20), a second buffer layer (40) located over said layer of ferroelectric material (30), a gate electrode (50) located over said second buffer layer (40), and source (60) and drain regions (70) located in said substrate (10).
Claim 6
Dependent Claim
42 words
The field effect transistor of Claim 5 further characterized by said buffer layers (20, 40) being comprised of a compound selected from the group comprising ZrO₂, La₂O₃, TiO₂, SiO₂, Bi₂O₃, Nb₂O₅, ThO₂, HfO₂, Ta₂O₅, SnO₂, CeO₃, Y₂O₃, Al₂O₃, MgO₂, Si₃N₄ and MgF₂.
Claim 7
Dependent Claim
29 words
The field effect transistor of Claim 5 further characterized by said ferroelectric material being Pb(Zr x Ti 1-x )O₂ wherein x is in the range of 0 to 1.0.
Claim 8
Dependent Claim
26 words
The field effect transistor of Claim 5 further characterized by said buffer layers (20, 40) and said layer of ferroelectric material (30) have coincident lateral edges.
Claim 9
Dependent Claim
18 words
The field effect transistor of Claim 5 further characterized by said gate electrode (50) being comprised of polysilicon.
Claim 10
Dependent Claim
20 words
The field effect transistor of Claim 5 further characterized by said gate electrode (50) being comprised of a noble metal.
Claim 11
Dependent Claim
39 words
The field effect transistor of Claim 5 further characterized by an insulating layer (80), with contact windows (90), located over said gate electrode (50), and a metalization layer (100) located over said insulating layer and in said contact windows.
Claim 12
Dependent Claim
38 words
The field effect transistor of Claim 11 further characterized by said insulating layer (100) having contact windows (90) formed in said insulating layer (100) to said gate electrode (50) and to said source and drain regions (60, 70).
Claim 13
Independent Claim
79 words
A method for fabricating a dielectric stack for a field effect transistor characterized by the steps of forming a substrate (10), establishing a first buffer layer (20) over said substrate (10), establishing a layer of ferroelectric material (30) over said first buffer layer (20), establishing a second buffer layer (40) over said layer of ferroelectric material (30), defining said second buffer layer (40), said layer of ferroelectric material (30) and said first buffer layer (20), and annealing said stack.
Claim 14
Dependent Claim
34 words
The method of Claim 13 further characterized by said second buffer layer (40), said layer of ferroelectric material (30) and said first buffer layer (20) being defined so that their lateral edges are coincident.
Claim 15
Independent Claim
133 words
A method for fabricating a field effect transistor characterized by the steps of forming a substrate (10), establishing a first buffer layer (20) over said substrate (10), establishing a layer of ferroelectric material (30) over said first buffer layer (20), establishing a second buffer layer (40) over said layer of ferroelectric material (30), defining said second buffer layer (40), said layer of ferroelectric material (30) and said first buffer layer (20), annealing, establishing and defining a gate electrode (50) over said second buffer layer (40), defining source (60) and drain regions (70) in said substrate (10), establishing and defining an insulating layer (80) with a contact window (90) to an element of the field effect transistor, and establishing a metalization layer (100) over said insulating layer (80) and in said contact window (90).
Claim 16
Dependent Claim
34 words
The method of Claim 15 further characterized by said second buffer layer (40), said layer of ferroelectric material (30) and said first buffer layer (20) being defined so that their lateral edges are coincident.
References Cited (Backward Citations)
US3832700A
Cited
WO1991016731A1
Cited
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