Patent US2449992A successfully refreshed from Google Patents.
Patent US5946594A successfully refreshed from Google Patents.
US5946594A
Expired / Lapsed
US
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Chemical vapor deposition of titanium from titanium tetrachloride and hydrocarbon reactants
Assignee: Mosaid Technologies Inc
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Filing: 1996-01-02
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Granted: 1999-08-31
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Expires: 2016-01-02
Abstract
Abstract A new process for depositing titanium metal layers via chemical vapor deposition is disclosed. The process provides deposited titanium layers having a high degree of conformality, even in trenches and contact openings having aspect ratios greater than 1:5. The reaction gases for the improved process are titanium tetrachloride and a hydrocarbon gas, which for a preferred embodiment of the process is methane. The reaction is carried out in a plasma environment created by a radio frequency source greater than 10 KHz. The key to obtaining titanium metal as a reaction product, rather than titanium carbide, is to set the plasma sustaining electrical power within a range that will remove just one hydrogen atom from each molecule of the hydrocarbon gas. In a preferred embodiment of the process, highly reactive methyl radicals (CH 3 --) are formed from methane gas. These radicals attack the titanium-chlorine bonds of the tetrachloride molecule and form chloromethane, which is evacuated from the chamber as it is formed. Titanium metal deposits on a wafer or other substrate that has been heated to a temperature within a preferred range of 200-500° C.
Inventors
- 👤 Ravi Iyer
- 👤 Sujit Sharan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 07:37
CPC Classifications
C; C23; C23C; C23C16/00; C23C16/06; C23C16/08; H; H10; H10P; H10P14/00; H10P14/40; H10P14/418; H10P14/42; H10P14/43; Y; Y10; Y10S; Y10S438/00; Y10S438/909
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
112 words
A chemical vapor deposition process for depositing a titanium metal layer on a substrate comprising the steps of: (a) placing the substrate within a plasma-enhanced chemical vapor deposition chamber; (b) admitting titanium tetrachloride molecules and molecules of at least one hydrocarbon gas into said chamber; (c) igniting a plasma which is maintained at a poser level sufficient to remove at least one hydrogen atom from each of the hydrocarbon gas molecules to form radicals; and (d) heating the substrate to a temperature sufficient to induce the radicals to scavenge chlorine atoms from the titanium tetrachloride molecules, thereby forming chlorinated hydrocarbon molecules and leaving titanium metal atoms on a surface of the substrate.
Claim 2
Dependent Claim
112 words
A chemical vapor deposition process for depositing a titanium metal layer on a substrate comprising the steps of: (a) placing the substrate within a plasma-enhanced chemical vapor deposition chamber; (b) admitting titanium tetrachloride molecules and molecules of at least one hydrocarbon gas into said chamber; (c) igniting a plasma which is maintained at a poser level sufficient to remove at least one hydrogen atom from each of the hydrocarbon gas molecules to form radicals; and (d) heating the substrate to a temperature sufficient to induce the radicals to scavenge chlorine atoms from the titanium tetrachloride molecules, thereby forming chlorinated hydrocarbon molecules and leaving titanium metal atoms on a surface of the substrate.
Claim 3
Dependent Claim
19 words
The process of claim 1, wherein the substrate is heated to a temperature within a range of 200-500° C.
Claim 4
Dependent Claim
33 words
The process of claim 1, wherein said hydrocarbon gas is selected from a group consisting of the compounds C n H 2n+2 , C n H 2n and C n H 2n-2 .
Claim 5
Dependent Claim
20 words
The process of claim 1, wherein said hydrocarbon gas is an alkane having fewer than five carbon atoms per molecule.
Claim 6
Dependent Claim
11 words
The process of claim 4, wherein said hydrocarbon gas is methane.
Claim 7
Dependent Claim
25 words
The process of claim 1, wherein said substrate is mounted on a heated susceptor, and said wafer is heated by thermal conduction from said susceptor.
Claim 8
Dependent Claim
26 words
The process of claim 1, wherein said titanium tetrachloride molecules are mixed with a carrier gas selected from the group consisting of helium, argon and hydrogen.
Claim 9
Dependent Claim
20 words
The process of claim 7, wherein the titanium tetrachloride molecules are introduced into said carrier gas in a bubbler apparatus.
Claim 10
Dependent Claim
32 words
The process of claim 7, wherein a liquid injector generates a fine spray of said titanium tetrachloride molecules, the spray then being passed through a vaporizer en route to the deposition chamber.
Claim 11
Dependent Claim
24 words
The process of claim 1, wherein said hydrocarbon gas is mixed with a carrier gas selected from the group consisting of helium and argon.
Claim 12
Dependent Claim
19 words
The process of claim 1, wherein non-depositing reaction products are removed from the deposition chamber as the process proceeds.
Claim 13
Dependent Claim
15 words
The process of claim 11, wherein an alkyl chloride gas is a principal reaction product.
Claim 14
Dependent Claim
42 words
The method of claim 1, wherein said deposition chamber is a cold wall deposition chamber, the walls of which are maintained at a temperature within a preferred range of 100-200° C. in order to prevent condensation of the titanium tetrachloride molecules thereon.
Claim 15
Dependent Claim
15 words
The method of claim 1, wherein said deposition chamber is a hot wall deposition chamber.
Claim 16
Dependent Claim
16 words
The method of claim 1, wherein said plasma is produced with a radio frequency AC source.
Claim 17
Dependent Claim
24 words
The method of claim 15, wherein said radio frequency AC source operates at a power setting within a range of 20 to 100 watts.
Claim 18
Dependent Claim
19 words
The method of claim 15, wherein said radio frequency AC source operates at a frequency greater than 10 KHz.
Claim 19
Dependent Claim
22 words
The method of claim 1, wherein said deposition chamber is maintained at a pressure within a range of 2 to 100 torr.
Claim 20
Dependent Claim
23 words
The method of claim 1, wherein said deposition chamber is maintained at a pressure within a preferred range of 2 to 5 torr.
Claim 21
Dependent Claim
28 words
The method of claim 1, wherein the titanium tetrachloride molecules and the hydrocarbon gas molecules are premixed to form a premixture before being admitted to the deposition chamber.
Claim 22
Dependent Claim
27 words
The method of claim 20, wherein a ratio of hydrocarbon gas molecules to titanium tetrachloride molecules in the premixture is between four and one thousand to one.
Claim 23
Dependent Claim
12 words
The method of claim 1, wherein said substrate is a semiconductor wafer.
Claim 24
Dependent Claim
122 words
A chemical vapor deposition process for depositing a titanium metal layer on a semiconductor wafer comprising the steps of: (a) placing the semiconductor wafer within a plasma-enhanced chemical vapor deposition chamber; (b) admitting titanium tetrachloride molecules and molecules of at least one hydrocarbon gas into said deposition chamber; (c) igniting a plasma which is maintained at a power level that is greater than a first ionization energy, but less than a second ionization energy, of the hydrocarbon gas molecules, thus forming hydrocarbon radicals; and (d) heating the wafer to a temperature sufficient to induce the hydrocarbon radicals to scavenge chlorine atoms from the titanium tetrachloride molecules, thereby forming chlorinated hydrocarbon molecules and leaving titanium metal atoms on a surface of the substrate.
Claim 25
Dependent Claim
122 words
A chemical vapor deposition process for depositing a titanium metal layer on a semiconductor wafer comprising the steps of: (a) placing the semiconductor wafer within a plasma-enhanced chemical vapor deposition chamber; (b) admitting titanium tetrachloride molecules and molecules of at least one hydrocarbon gas into said deposition chamber; (c) igniting a plasma which is maintained at a power level that is greater than a first ionization energy, but less than a second ionization energy, of the hydrocarbon gas molecules, thus forming hydrocarbon radicals; and (d) heating the wafer to a temperature sufficient to induce the hydrocarbon radicals to scavenge chlorine atoms from the titanium tetrachloride molecules, thereby forming chlorinated hydrocarbon molecules and leaving titanium metal atoms on a surface of the substrate.
Claim 26
Dependent Claim
22 words
The method of claim 23, wherein the deposition chamber is maintained at a pressure within a range of 2 to 10 torr.
Claim 27
Dependent Claim
36 words
The method of Claim 23, wherein said power level comprises a radio frequency AC source operating at a power setting within a range of 20 to 100 watts and at a frequency greater than 10 KHz.
Claim 28
Dependent Claim
51 words
The method of claim 23, wherein the titanium tetrachloride molecules and the hydrocarbon gas molecules are premixed to form a premixture prior to their admission to the deposition chamber, with a ratio of methane gas molecules to titanium tetrachloride molecules in the premixture being between four and one thousand to one.
Claim 29
Dependent Claim
11 words
The method of claim 23, wherein the hydrocarbon gas is methane.
Claim 30
Dependent Claim
33 words
The process of claim 23, wherein said hydrocarbon gas is selected from a group consisting of the compounds C n H 2n+2 , C n H 2n and C n H 2n-2 .
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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) | 2002-08-30 | 2003-03-01 | 2003-08-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-08-30 | 2007-03-01 | 2007-08-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-08-30 | 2011-03-01 | 2011-08-31 | $7700.00 | Window Closed / Lapsed |