EP0452891A2
Expired / Lapsed
EP
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Process for forming titanium silicide on a semiconductor wafer
Assignee: Applied Materials Inc
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Filing: 1991-04-16
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Granted: —
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Expires: 2011-04-16
Abstract
Abstract A process is disclosed for forming a conductive layer of titanium silicide on a silicon semiconductor wafer which comprises the steps of forming a titanium layer over the wafer in a vacuum deposition chamber in the substantial absence of oxygen and/or oxygen-bearing gases; transferring the titanium coated wafer to a sealed annealing chamber without substantially exposing the newly formed titanium layer to oxygen and/or oxygen-bearing gases; and annealing the titanium-coated silicon semiconductor wafer in a nitrogen-bearing atmosphere in the sealed annealing chamber, and in the substantial absence of oxygen and/or oxygen-bearing gases, to form a titanium silicide layer as well as titanium nitride on the surface which inhibits migration of underlying silicon to the surface. In a preferred embodiment, the improved process further includes a cleaning step which uses an rf plasma and at least one reactive gas to clean the wafer in a cleaning chamber prior to the deposition step and the cleaned wafer is then transferred to the vacuum deposition chamber from the cleaning chamber without substantially exposing the wafer to oxygen and/or oxygen-bearing gases.
Inventors
- 👤 Jaim Nulman
- 👤 Dan Maydan
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 01:48
CPC Classifications
H; H10; H10P; H10P72/00; H10P72/04; H10P72/0451; H10P72/0452; H10P72/0454; H10D; H10D30/00; H10D30/01; H10D30/021; H10D30/0212; H10D30/0223; H10D64/00; H10D64/01; H10D64/011; H10D64/0111; H10D64/0112; H10D64/013; H10D64/01302; H10D64/01304; H10D64/01306; H10D64/01308; H10D64/0131; H10P70/00; H10P70/20; H10P70/23; H10P72/0468
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
76 words
A process for forming a conductive layer of titanium silicide on a silicon semiconductor wafer which comprises: forming, by vacuum deposition, a titanium layer over the wafer and annealing the titanium-coated silicon semiconductor wafer in a nitrogen-bearing atmosphere, the whole process being carried out in the substantial absence of oxygen and/or oxygen-bearing gases, to form a titanium silicide layer as well as titanium nitride on the surface which inhibits migration of underlying silicon to the surface.
Claim 2
Dependent Claim
31 words
The process of claim 1, further comprising the step of cleaning the wafer to remove oxides and other materials from the silicon surface thereon prior to said titanium layer deposition step.
Claim 3
Dependent Claim
119 words
A process for forming a conductive layer of titanium silicide on a silicon semiconductor wafer, especially according to claim 1 or 2, which comprises: a. forming a titanium layer over the wafer in a vacuum deposition chamber in the substantial absence of oxygen and/or oxygen-bearing gases; b. transferring the titanim-coated wafer to a sealed annealing chamber without substantially exposing the newly formed titanium layer to oxygen and/or oxygen-bearing gases; and c. annealing the titanium-coated silicon semiconductor wafer in a nitrogen-bearing atmosphere in said sealed annealing chamber, and in the substantial absence of oxygen and/or oxygen-bearing gases, to form a titanium silicide layer as well as titanium nitride on the surface which inhibits migration of underlying silicon to the surface.
Claim 4
Dependent Claim
39 words
The process of any of the preceding claims, wherein said titanium layer is formed in thickness from 10 nm to 500 nm (100 Å to 5000 Å), preferably from 10 nm to 100 nm (100 Å to 1000 Å).
Claim 5
Dependent Claim
53 words
The process of any of the preceding claims, which comprises the further step of cleaning said wafer in a cleaning chamber to remove oxides and other materials from the silicon surfaces thereon prior to said titanium deposition step, and then transferring said cleaned wafer from said cleaning chamber to said vacuum deposition chamber.
Claim 6
Dependent Claim
50 words
The process of claim 5, wherein said cleaning step further comprises cleaning said wafer using a gaseous mixture which includes at least one reactive gas, preferaby selected from the class consisting of NF₃, 1-2 carbon flourinated hydrocarbons, and mixtures of same, while maintaining an rf plasma in said cleaning chamber.
Claim 7
Dependent Claim
71 words
The process of claim 5 or 6, in which the cleaning step comprises flowing into said cleaning chamber said gaseous mixture containing at least one reactive gas at a rate of from 2 to 500 sccm reactive gas and from 10 to 1000 sccm carrier gas, while maintaining said plasma preferably at a power ranging from 20 to 500 watts for a period of time ranging from 1 to 500 seconds.
Claim 8
Dependent Claim
55 words
A process of one of claims 5 to 7, wherein the pressure in said cleaning chamber is maintained within a range of from 1.333 · 10 ⁻³ to 133 · 10 ⁻³ mbar (1 to 100 milliTorr) and the temperature in the fluid cleaning chamber is maintained within a range of from 27°C to 200°C.
Claim 9
Dependent Claim
58 words
The process of one of the preceding claims, wherein said annealing is carried out in a first annealing step at a temperature ranging from 600°C up to 695°C, preferably to 675°C and/or for a time period ranging from 20 seconds to 60 seconds by raising the temperature of said wafer at a rate of from 5°C/second to 150°C/second.
Claim 10
Dependent Claim
61 words
The process of one of the preceding claims, wherein said nitrogen-bearing atmosphere in said annealing chamber is maintained, during said first annealing step, at a pressure ranging from 133 · 10 ⁻³ mbar to 1064 mbar (100 milliTorr to 800 Torr) while flowing one or more nitrogen-bearing gases into said chamber at a rate ranging from 500 to 10 000 sccm.
Claim 11
Dependent Claim
43 words
The process of one of the preceding claims, wherein said wafer is selectively etched after said first annealing step to remove titanium nitride and unreacted titanium and then subsequently annealed in a second annealing step at a temperature ranging from 800°C to 900°C.
Claim 12
Dependent Claim
61 words
The process of one of the preceding claims, wherein transferring said wafer from said cleaning chamber to said vacuum deposition chamber and/or from said vacuum deposition chamber to said annealing chamber is effected through a sealed central chamber which is interconnected to both said cleaning chamber and said vacuum deposition chamber and/or said vacuum deposition chamber and said sealed annealing chamber.
Claim 13
Dependent Claim
29 words
The process of claim 12 which further comprises maintaining said sealed central chamber at a pressure ranging from 13.3 ⁻⁹ to 13.3 ⁻⁵ mbar (10 ⁻⁹ to 10⁻⁵ Torr).
References Cited (Backward Citations)
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