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US6020024A
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Method for forming high dielectric constant metal oxides
Assignee: VLSI Technology LLC
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Filing: 1997-08-04
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Granted: 2000-02-01
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Expires: 2017-08-04
Abstract
Abstract A method for forming a metal gate (20) structure begins by providing a semiconductor substrate (12). The semiconductor substrate (12) is cleaned to reduce trap sites. A nitrided layer (14) having a thickness of less than approximately 20 Angstroms is formed over the substrate (12). This nitrided layer prevents the formation of an oxide at the substrate interface and has a dielectric constant greater than 3.9. After the formation of the nitrided layer(14), a metal oxide layer (16) having a permittivity value of greater than roughly 8.0 is formed over the nitrided layer (14). A metal gate (20) is formed over the nitrided layer whereby the remaining composite gate dielectric (14 and 16) has a larger physical thickness but a high-performance equivalent oxide thickness (EOT).
Inventors
- 👤 Bikas Maiti
- 👤 Philip J. Tobin
- 👤 Rama I. Hegde
- 👤 Jesus Cuellar
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 01:50
CPC Classifications
H; H10; H10D; H10D64/00; H10D64/01; H10D64/013; H10D64/01302; H10D64/01332; H10D64/01336; H10D64/0134; H10D30/00; H10D30/01; H10D30/021; H10D30/0223; H10D30/0227; H10D64/01342; H10D64/01344; H10D64/01348; H10D64/60; H10D64/66; H10D64/667; H10D64/669; H10D64/68; H10D64/681; H10D64/685; H10D64/691; H10D64/693
Claims Analysis
Total Claims: 29
Claim 1
Independent Claim
90 words
A method for forming a semiconductor structure, the method comprising the steps of: providing a semiconductor substrate having a surface; forming an oxidation barrier layer over the surface of the semiconductor substrate; forming a metal oxide layer over the oxidation barrier layer; and forming a gate electrode overlying the metal oxide layer and forming source and drain electrodes within the semiconductor substrate wherein the gate electrode controls current flow between source and drain electrodes using the oxidation barrier layer and the metal oxide layer as a composite gate dielectric layer.
Claim 2
Independent Claim
90 words
A method for forming a semiconductor structure, the method comprising the steps of: providing a semiconductor substrate having a surface; forming an oxidation barrier layer over the surface of the semiconductor substrate; forming a metal oxide layer over the oxidation barrier layer; and forming a gate electrode overlying the metal oxide layer and forming source and drain electrodes within the semiconductor substrate wherein the gate electrode controls current flow between source and drain electrodes using the oxidation barrier layer and the metal oxide layer as a composite gate dielectric layer.
Claim 3
Dependent Claim
30 words
The method of claim 1 wherein the step of forming a metal oxide layer comprises: selecting a metal oxide layer which is not chemically stable in a presence of silicon.
Claim 4
Dependent Claim
62 words
The method of claim 2 wherein the step of forming a metal oxide layer comprises: selecting the metal oxide layer from the group consisting of: tantalum pentoxide (Ta 2 O 5 ), titanium dioxide (TiO 2 ), lead zirconium titanate (PZT), barium strontium titanate (BST), strontium bismuth titantate (SBT), and niobium oxide (Nb 2 O 3 or Nb 2 O 5 ).
Claim 5
Dependent Claim
29 words
The method of claim 1 wherein the step of forming a metal oxide layer comprises: selecting a metal oxide layer which is chemically stable in a presence of silicon.
Claim 6
Dependent Claim
47 words
The method of claim 4 wherein the step of forming a metal oxide layer comprises: selecting the metal oxide layer from the group consisting of: yttrium oxide (Y 2 O 3 ), zirconium oxide (ZrO 2 ), calcium oxide (CaO), beryllium oxide (BeO), and magnesium oxide (MgO).
Claim 7
Dependent Claim
73 words
The method of claim 1 wherein the step of forming a metal oxide layer comprises: sputtering a metallic material on the oxidation barrier layer; and exposing the metallic material to an oxidation environment wherein the oxidation environment changes the metallic material to a metal oxide material, wherein the oxidation barrier layer prevents a region of the semiconductor substrate that is in close proximity to the composite gate dielectric layer from being significantly oxidized.
Claim 8
Dependent Claim
80 words
The method of claim 1 wherein the step of forming a metal oxide layer comprises: chemical vapor depositing a metallic oxide material on the oxidation barrier layer; and exposing the metallic oxide material to an anneal environment wherein the anneal environment reduces oxygen vacancies and improves the bonding in the metallic oxide material, wherein the oxidation barrier layer prevents a region of the semiconductor substrate that is in close proximity to the composite gate dielectric layer from being significantly oxidized.
Claim 9
Dependent Claim
36 words
The method of claim 1 wherein the step of forming a gate electrode comprises: forming the gate electrode having a lower portion made of a metallic material and an upper portion made of a polysilicon material.
Claim 10
Dependent Claim
32 words
The method of claim 8 wherein the step of forming a gate electrode comprises: siliciding a top portion of the polysilicon material to form a top silicide portion of the gate electrode.
Claim 11
Dependent Claim
24 words
The method of claim 1 wherein the step of forming the oxidation barrier layer comprises: forming the oxidation barrier layer as an oxynitride layer.
Claim 12
Dependent Claim
44 words
The method of claim 10 wherein the step of forming the oxidation barrier layer comprises: exposing the semiconductor substrate to an environment provided with a source gas selected from the group consisting of: N 2 O, NO, NH 3 , and N 2 .
Claim 13
Dependent Claim
27 words
The method of claim 10 wherein the step of forming the oxidation barrier layer comprises: ion implanting an oxide formed over the semiconductor substrate with nitrogen atoms.
Claim 14
Dependent Claim
28 words
The method of claim 1 wherein the step of forming the oxidation barrier layer comprises: forming the oxidation barrier layer between 2 angstroms and 15 angstroms in thickness.
Claim 15
Dependent Claim
27 words
The method of claim 1 wherein the step of forming the oxidation barrier layer comprises: forming the oxidation barrier layer having a dielectric constant greater than 3.9.
Claim 16
Dependent Claim
54 words
The method of claim 1 wherein the steps of forming the oxidation barrier layer and the metal oxide layer comprises: forming the oxidation barrier layer as a material that is chemically stable when exposed to silicon; and forming the metal oxide layer as a layer which is not stable in a presence of silicon.
Claim 17
Dependent Claim
42 words
The method of claim 1 wherein the step of forming the oxidation barrier layer comprises: cleaning the semiconductor substrate with HF and passivating a top surface of the semiconductor substrate with a H 2 environment before formation of the oxidation barrier layer.
Claim 18
Dependent Claim
52 words
The method of claim 1 wherein the step of forming the metal oxide layer comprises: forming the metal oxide layer as a composite metal oxide layer having a first metal oxide layer overlying a second metal oxide layer wherein the first metal oxide layer is different from the second metal oxide layer.
Claim 19
Dependent Claim
50 words
The method of claim 17 wherein the step of forming the metal oxide layer comprises: forming the first metal oxide layer by depositing one or more atomic layers via atomic layer epitaxy; and forming the second metal oxide layer by depositing one or more atomic layers via atomic layer epitaxy.
Claim 20
Dependent Claim
32 words
The method of claim 1 wherein the step of forming the oxidation barrier layer comprises: ion implanting nitrogen atoms into the semiconductor substrate to form silicon nitride as the oxidation barrier layer.
Claim 21
Dependent Claim
32 words
The method of claim 1 further comprising the step of: passivating a surface of the semiconductor substrate so that oxidation on the semiconductor substrate is reduced before the oxidation barrier is formed.
Claim 22
Dependent Claim
33 words
The method of claim 1 wherein the step of forming the gate electrode comprises: forming the gate electrode having a TiN portion and a W portion to reduce stress in the semiconductor structure.
Claim 23
Independent Claim
128 words
A method for forming a semiconductor structure, the method comprising the steps of: providing a semiconductor substrate having a surface; forming an oxidation barrier layer over the surface of the semiconductor substrate by exposing the semiconductor substrate to a nitrogen environment, the oxidation barrier layer having a dielectric constant between 3.9 and 8.0; forming a metal oxide layer over the oxidation barrier layer, the metal oxide layer having a dielectric constant above 7.8; forming a metallic gate electrode overlying the metal oxide layer; and forming source and drain electrodes within the semiconductor substrate and self-aligned to the metallic gate electrode wherein the gate electrode controls current flow between source and drain electrodes using the oxidation barrier layer and the metal oxide layer as a composite gate dielectric layer.
Claim 24
Independent Claim
128 words
A method for forming a semiconductor structure, the method comprising the steps of: providing a semiconductor substrate having a surface; forming an oxidation barrier layer over the surface of the semiconductor substrate by exposing the semiconductor substrate to a nitrogen environment, the oxidation barrier layer having a dielectric constant between 3.9 and 8.0; forming a metal oxide layer over the oxidation barrier layer, the metal oxide layer having a dielectric constant above 7.8; forming a metallic gate electrode overlying the metal oxide layer; and forming source and drain electrodes within the semiconductor substrate and self-aligned to the metallic gate electrode wherein the gate electrode controls current flow between source and drain electrodes using the oxidation barrier layer and the metal oxide layer as a composite gate dielectric layer.
Claim 25
Dependent Claim
53 words
The method of claim 22 wherein the steps of forming the oxidation barrier layer and the metal oxide layer comprises: forming the oxidation barrier layer as a material that is chemically stable when exposed to silicon; and forming the metal oxide layer as a layer which is not stable in contact with silicon.
Claim 26
Dependent Claim
73 words
The method of claim 22 wherein the step of forming a metal oxide layer comprises: sputtering a metallic material on the oxidation barrier layer; and exposing the metallic material to an oxidation environment wherein the oxidation environment changes the metallic material to a metal oxide material, wherein the oxidation barrier layer prevents a region of the semiconductor substrate that is in close proximity to the composite gate dielectric layer from being significantly oxidized.
Claim 27
Dependent Claim
76 words
The method of claim 22 wherein the step of forming a metal oxide layer comprises: chemical vapor depositing a metallic oxide material on the oxidation barrier layer; and exposing the metallic oxide material to an oxidation environment wherein the oxidation environment anneals oxygen vacancies in the metallic oxide material, wherein the oxidation barrier layer prevents a region of the semiconductor substrate that is in close proximity to the composite gate dielectric layer from being significantly oxidized.
Claim 28
Independent Claim
199 words
A method for forming a semiconductor structure, the method comprising the steps of: providing a silicon substrate; annealing the silicon substrate in a hydrogen-containing environment to passivate a surface of the silicon substrate; forming an oxidation barrier layer over the surface of the silicon substrate by exposing the semiconductor substrate to a nitrogen environment, the oxidation barrier layer having a dielectric constant between 3.9 and 8.0 and being chemically stable in contact to silicon; forming a metal oxide layer over the oxidation barrier layer, the metal oxide layer having a dielectric constant above 7.8 and being chemically unstable in contact to silicon; forming a metallic gate electrode overlying the metal oxide layer wherein a lower portion of the metallic gate electrode is made of a metal material, a middle portion of the metallic gate electrode is made of polysilicon, and an upper portion of the metallic gate electrode is made of a silicide material; and forming source and drain electrodes within the silicon substrate and self-aligned to the metallic gate electrode wherein the gate electrode controls current flow between source and drain electrodes using the oxidation barrier layer and the metal oxide layer as a composite gate dielectric layer.
Claim 29
Independent Claim
199 words
A method for forming a semiconductor structure, the method comprising the steps of: providing a silicon substrate; annealing the silicon substrate in a hydrogen-containing environment to passivate a surface of the silicon substrate; forming an oxidation barrier layer over the surface of the silicon substrate by exposing the semiconductor substrate to a nitrogen environment, the oxidation barrier layer having a dielectric constant between 3.9 and 8.0 and being chemically stable in contact to silicon; forming a metal oxide layer over the oxidation barrier layer, the metal oxide layer having a dielectric constant above 7.8 and being chemically unstable in contact to silicon; forming a metallic gate electrode overlying the metal oxide layer wherein a lower portion of the metallic gate electrode is made of a metal material, a middle portion of the metallic gate electrode is made of polysilicon, and an upper portion of the metallic gate electrode is made of a silicide material; and forming source and drain electrodes within the silicon substrate and self-aligned to the metallic gate electrode wherein the gate electrode controls current flow between source and drain electrodes using the oxidation barrier layer and the metal oxide layer as a composite gate dielectric layer.
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| 7.5 Years (Year 8) | 2007-01-31 | 2007-08-02 | 2008-02-01 | $3760.00 | Window Closed / Lapsed |
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