Patent US4803539A successfully refreshed from Google Patents.
US4803539A
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Dopant control of metal silicide formation
Assignee: International Business Machines Corp
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Filing: 1985-03-29
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Granted: 1989-02-07
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Expires: 2005-03-29
Abstract
Abstract A structure and method are described for forming different metal silicide phases, using the same metallurgy and the same processing steps. A layer of metal is deposited on a silicon substrate and is heated to thermally convert the metal-silicon combination to a metal silicide. The metal silicide phase which forms is strongly dependent upon the dopant and doping level in the silicon substrate, for various combinations of metal and dopant. Thus, different metal silicides can be formed on different regions of the substrate in accordance with the dopant and doping levels in those different regions, even though the process steps and metallurgy are the same. These different metal silicides can be tailored for different applications, including ohmic contacts, diode barrier contacts, interconnection lines, gate contacts, and diffusion barriers.
Inventors
- 👤 Peter A. Psaras
- 👤 King-Ning Tu
- 👤 Richard D Thompson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 19:01
CPC Classifications
H; H10; H10D; H10D30/00; H10D30/01; H10D30/021; H10D30/0223; B; B01; B01J; B01J37/00; B01J37/08; B01J37/10; B01J37/105; H10D62/00; H10D62/80; H10D62/83; H10D64/00; H10D64/01; H10D64/011; H10D64/0111; H10D64/0112; H10D64/012; H10D64/0121; H10D64/60; H10D64/62
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
159 words
A metal silicide-silicon structure including thermally formed metal silicides including the same metal and having first and second compound phases in first and second regions of said structure, comprising: a substrate having a first region thereof which is doped with a selected dopant to a level sufficient to cause said first region to affect the compound phase of a metal silicide thermally formed thereon, said substrate including a second region that is either undoped or doped with an impurity incapable of affecting the comound phase of a metal silicide formed thereon or doped with an impurity capable of affecting said phase in an amount sufficiently low that said phase is unaffected, a metal silicide thermally formed on said first and second regions and including the same metal in said first and second regions, the compound phase of said metal silicide in said first region being different than the compound phase of said metal silicide formed in said second region.
Claim 2
Dependent Claim
159 words
A metal silicide-silicon structure including thermally formed metal silicides including the same metal and having first and second compound phases in first and second regions of said structure, comprising: a substrate having a first region thereof which is doped with a selected dopant to a level sufficient to cause said first region to affect the compound phase of a metal silicide thermally formed thereon, said substrate including a second region that is either undoped or doped with an impurity incapable of affecting the comound phase of a metal silicide formed thereon or doped with an impurity capable of affecting said phase in an amount sufficiently low that said phase is unaffected, a metal silicide thermally formed on said first and second regions and including the same metal in said first and second regions, the compound phase of said metal silicide in said first region being different than the compound phase of said metal silicide formed in said second region.
Claim 3
Dependent Claim
11 words
The structure of claim 1, wherein said silicon is single crystal.
Claim 4
Dependent Claim
10 words
The structure of claim 1, where said silicon is polycrystalline
Claim 5
Dependent Claim
10 words
The structure of claim 1, where said silicon is n-doped.
Claim 6
Dependent Claim
10 words
The structure of claim 1, where said silicon is p-doped.
Claim 7
Dependent Claim
18 words
The structure of claim 1, where said doping level is greater than approximately 10 18 atoms/cm 3 .
Claim 8
Dependent Claim
25 words
The structure of claim 1, where said metal constituent is selected from the group consisting of Ti, Mo, W, Ta, Rh, Ni, Pt and Cr.
Claim 9
Dependent Claim
59 words
The structure of claim 1, where said dopant is an element which can form a compound with said metal constituent at the temperature of said thermal conversion, said compound having a metal point which is greater than the melting point of the silicide phase which would form on said undoped silicon substrate at the temperature of said thermal conversion.
Claim 10
Dependent Claim
33 words
The structure of claim 1, where said metal constituent is selected from the group consisting of Ti, Mo, W. Ta, Cr, Hf, Zr, Rh, Co, Ni, Fe, Mn, and said dopant is B.
Claim 11
Dependent Claim
25 words
The structure of claim 1, wherein said metal constituent is selected from the group consisting of Pt, Rh, and Ni, and said dopant is Sb.
Claim 12
Dependent Claim
27 words
The structure of claim 1, where said metal constituent is selected from the group consisting of Ti, Ni, Rh, Fe, and Mn, and said dopant is P.
Claim 13
Dependent Claim
24 words
The structure of claim 1, where said metal constituent is selected from the group consisting of Ni and Fe, and said dopant is As.
Claim 14
Dependent Claim
91 words
A metal silicide-silicon structure, including: a first silicon region which is undoped or doped to a level less than about 10 18 atoms/cm 3 , a second silicon region containing a selected dopant in an amount at least about 10 18 atoms/cm 3 , metal silicides simultaneously thermally formed with said first and second silicon regions, said metal silicides in said first and second regions being comprised of the same metal, and having a different stoichiometry, where the stoichiometry is dependent upon the dopant and doping level of said silicon regions.
Claim 15
Dependent Claim
91 words
A metal silicide-silicon structure, including: a first silicon region which is undoped or doped to a level less than about 10 18 atoms/cm 3 , a second silicon region containing a selected dopant in an amount at least about 10 18 atoms/cm 3 , metal silicides simultaneously thermally formed with said first and second silicon regions, said metal silicides in said first and second regions being comprised of the same metal, and having a different stoichiometry, where the stoichiometry is dependent upon the dopant and doping level of said silicon regions.
Claim 16
Dependent Claim
20 words
The structure of claim 13, where said first silicon region is single crystal and said second silicon region is polycrystalline.
Claim 17
Dependent Claim
20 words
The structure of claim 13, where said first silicon region is polycrystalline and said second silicon region is single crystal.
Claim 18
Dependent Claim
14 words
The structure of claim 13, where said first and second silicon regions are coplanar.
Claim 19
Dependent Claim
14 words
The structure of claim 13, where said first and second silicon regions are non-coplanar.
Claim 20
Dependent Claim
40 words
The structure of claim 13, where said dopant and said metal can form a compound having a melting point greater than the melting point of the metal silicide phase formed with undoped silicon at the temperature of said thermal formation.
Claim 21
Dependent Claim
24 words
The structure of claim 18, where said dopant is selected in accordance with said metal from the group consisting B, Sb, P, and As.
Claim 22
Dependent Claim
122 words
A metal silicide-silicon structure, including: a first doped silicon substrate region and a second undoped silicon substrate region, a layer of metal silicide formed by thermal conversion of a metal deposited on said first and second silicon substrate regions, said metal silicide being formed on both said doped and undoped silicon regions, said metal silicide being substantially comprised of a single metal constituent, wherein the dopant in said doped silicon region and its concentration are such that the temperature ranges of formation of at least two metal silicide compound phases are shifted during said thermal conversion, to produce a silicide compound phase on said doped silicon substrate region that is not present in the metal silicide formed on said undoped substrate region.
Claim 23
Dependent Claim
122 words
A metal silicide-silicon structure, including: a first doped silicon substrate region and a second undoped silicon substrate region, a layer of metal silicide formed by thermal conversion of a metal deposited on said first and second silicon substrate regions, said metal silicide being formed on both said doped and undoped silicon regions, said metal silicide being substantially comprised of a single metal constituent, wherein the dopant in said doped silicon region and its concentration are such that the temperature ranges of formation of at least two metal silicide compound phases are shifted during said thermal conversion, to produce a silicide compound phase on said doped silicon substrate region that is not present in the metal silicide formed on said undoped substrate region.
Claim 24
Dependent Claim
98 words
A metal silicide-silicon structure, including: a first doped silicon substrate region including a selected dopant in an amount sufficient to affect the phase of a metal silicide thermally formed on said first region, a second silicon substrate region doped to a level insufficient to affect the phase of a metal silicide thermally formed on said second region, a metal silicide simultaneously thermally formed on both said first and second regions and containing the same metal, the compound phase of said metal silicide formed in said first region being different than the compound phase formed in said second region.
Claim 25
Dependent Claim
98 words
A metal silicide-silicon structure, including: a first doped silicon substrate region including a selected dopant in an amount sufficient to affect the phase of a metal silicide thermally formed on said first region, a second silicon substrate region doped to a level insufficient to affect the phase of a metal silicide thermally formed on said second region, a metal silicide simultaneously thermally formed on both said first and second regions and containing the same metal, the compound phase of said metal silicide formed in said first region being different than the compound phase formed in said second region.
Claim 26
Dependent Claim
104 words
A metal silicide-silicon structure, comprising: a first silicon substrate region including a selected dopant in an amount sufficient to influence the phase of a selected metal silicide compound thermally formed thereon, a second silicon substrate region on which a different phase of said selected metal silicide compound is to be thermally formed, said second silicon substrate region being characterized by the absence of selected dopant in said sufficient amount, a first compound phase of said selected metal silicide thermally formed on said first silicon substrate region, and a second compound phase of said selected metal silicide thermally formed on said second silicon substrate region.
Claim 27
Dependent Claim
104 words
A metal silicide-silicon structure, comprising: a first silicon substrate region including a selected dopant in an amount sufficient to influence the phase of a selected metal silicide compound thermally formed thereon, a second silicon substrate region on which a different phase of said selected metal silicide compound is to be thermally formed, said second silicon substrate region being characterized by the absence of selected dopant in said sufficient amount, a first compound phase of said selected metal silicide thermally formed on said first silicon substrate region, and a second compound phase of said selected metal silicide thermally formed on said second silicon substrate region.
Claim 28
Dependent Claim
19 words
The structure of claim 21, wherein said first and second compound phases are simultaneously formed in the same steps.
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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) | 1992-02-07 | 1992-08-08 | 1993-02-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-02-07 | 1996-08-08 | 1997-02-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-02-07 | 2000-08-08 | 2001-02-07 | $7700.00 | Window Closed / Lapsed |