US5407861A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Metallization over tungsten plugs
Assignee: STMicroelectronics SRL
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Filing: 1993-05-26
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Granted: 1995-04-18
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Expires: 2013-05-26
Abstract
Abstract A plug contact process wherein, after contact holes are etched, an adhesion layer (such as Ti/TiN) and a filler metal (such as tungsten) are deposited overall. A two-stage etch is then used: First, the filler metal is etched preferentially with respect to the adhesion layer, until an endpoint signal first indicates that said adhesion layer is exposed. No overetch is used at this stage. Thereafter a nonpreferential etch is used to clear residues of the filler metal, while also uniformly reducing the height of the adhesion layer. This prevents the tops of the plugs in the contact holes from being recessed. Aluminum (or other metal) is then deposited and patterned (using a stack etch to remove the undesired portions of the adhesion layer too) to implement the desired wiring pattern. This process thereby reduces voids, and resulting metallization defects, in a process with high-aspect-ratio contacts. In addition, the residual adhesion layer helps to reduce electromigration.
Inventors
- 👤 Maria S. Marangon
- 👤 Andrea Marmiroli
- 👤 Giorgio Desanti
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 13:51
CPC Classifications
H; H10; H10W; H10W20/00; H10W20/01; H10W20/031; H10W20/056; H10W20/062; Y; Y10; Y10S; Y10S438/00; Y10S438/963; Y10S438/97; Y10S438/974
Claims Analysis
Total Claims: 52
Claim 1
Independent Claim
185 words
An integrated circuit fabrication method, comprising the steps of: (a.) providing a substrate which includes one or more semiconductor devices, with an insulating layer thereover; (b.) etching contact holes in desired locations of said insulating layer; (c.) depositing an adhesion layer on said insulating layer and into said contact holes; (d.) depositing a filler metal overall; (e.) applying RF power to a controlled gas mixture to perform a first unpatterned etch, which etches said filler metal preferentially with respect to said adhesion layer, until said adhesion layer is exposed but said filler metal has not yet been removed outside said contact holes; (f.) applying RF power to a controlled gas mixture to perform a second unpatterned etch, which etches said filler metal equally with said adhesion layer, until said filler metal has been totally removed outside: said contact holes, but said adhesion layer remains in at least some locations; (g.) depositing a metallization layer overall; and (h.) patterning said metallization layer and said adhesion layer to implement a desired wiring pattern which includes connection to said filler metal in multiple ones of said contact holes.
Claim 2
Dependent Claim
185 words
An integrated circuit fabrication method, comprising the steps of: (a.) providing a substrate which includes one or more semiconductor devices, with an insulating layer thereover; (b.) etching contact holes in desired locations of said insulating layer; (c.) depositing an adhesion layer on said insulating layer and into said contact holes; (d.) depositing a filler metal overall; (e.) applying RF power to a controlled gas mixture to perform a first unpatterned etch, which etches said filler metal preferentially with respect to said adhesion layer, until said adhesion layer is exposed but said filler metal has not yet been removed outside said contact holes; (f.) applying RF power to a controlled gas mixture to perform a second unpatterned etch, which etches said filler metal equally with said adhesion layer, until said filler metal has been totally removed outside: said contact holes, but said adhesion layer remains in at least some locations; (g.) depositing a metallization layer overall; and (h.) patterning said metallization layer and said adhesion layer to implement a desired wiring pattern which includes connection to said filler metal in multiple ones of said contact holes.
Claim 3
Dependent Claim
19 words
The method of claim 1, wherein at least some ones of said contact holes make contact to said substrate.
Claim 4
Dependent Claim
26 words
The method of claim 1, wherein said substrate consists essentially of silicon, and at least some ones of said contact holes make contact to said substrate.
Claim 5
Dependent Claim
12 words
The method of claim 1, wherein said filler metal consists of tungsten.
Claim 6
Dependent Claim
15 words
The method of claim 1, wherein said filler metal is deposited by chemical vapor deposition.
Claim 7
Dependent Claim
23 words
The method of claim 1, wherein said insulating layer includes at least 25% at of silicon and at least 40% at of oxygen.
Claim 8
Dependent Claim
24 words
The method of claim 1, wherein said step (b) etches at least some of said contact holes to have a greater depth than width.
Claim 9
Dependent Claim
14 words
The method of claim 1, wherein said insulating layer consists essentially of silicon oxide.
Claim 10
Dependent Claim
13 words
The method of claim 1, wherein said insulating layer comprises a silicate glass.
Claim 11
Dependent Claim
10 words
The method of claim 1, wherein said metallization comprises aluminum.
Claim 12
Dependent Claim
26 words
The method of claim 1, wherein said adhesion layer is selected from the group consisting of titanium, titanium nitride, and composites of titanium with titanium nitride.
Claim 13
Dependent Claim
178 words
An integrated circuit fabrication method, comprising the steps of: (a.) providing a substrate which includes one or more semiconductor devices, with an insulating layer thereover; (b.) etching contact holes in desired locations of said insulating layer; (c.) depositing an adhesion layer on said insulating layer and into said contact holes; (d.) depositing a filler metal overall; (e.) applying RF power to a controlled gas mixture to perform a first etch, which etches said filler metal preferentially with respect to said adhesion layer, and stopping said first etch when erosion of said adhesion layer is detected; (f.) applying RF power to a controlled gas mixture to perform a timed second etch, which etches said filler metal equally with said adhesion layer, until said filler metal has been totally removed outside said contact holes, but said adhesion layer remains in at least some locations; (g.) depositing a metallization layer overall; and (h.) patterning said metallization layer and said adhesion layer to implement a desired wiring pattern which includes connection to said filler metal in multiple ones of said contact holes.
Claim 14
Dependent Claim
178 words
An integrated circuit fabrication method, comprising the steps of: (a.) providing a substrate which includes one or more semiconductor devices, with an insulating layer thereover; (b.) etching contact holes in desired locations of said insulating layer; (c.) depositing an adhesion layer on said insulating layer and into said contact holes; (d.) depositing a filler metal overall; (e.) applying RF power to a controlled gas mixture to perform a first etch, which etches said filler metal preferentially with respect to said adhesion layer, and stopping said first etch when erosion of said adhesion layer is detected; (f.) applying RF power to a controlled gas mixture to perform a timed second etch, which etches said filler metal equally with said adhesion layer, until said filler metal has been totally removed outside said contact holes, but said adhesion layer remains in at least some locations; (g.) depositing a metallization layer overall; and (h.) patterning said metallization layer and said adhesion layer to implement a desired wiring pattern which includes connection to said filler metal in multiple ones of said contact holes.
Claim 15
Dependent Claim
19 words
The method of claim 12, wherein at least some ones of said contact holes make contact to said substrate.
Claim 16
Dependent Claim
26 words
The method of claim 12, wherein said substrate consists essentially of silicon, and at least some ones of said contact holes make contact to said substrate.
Claim 17
Dependent Claim
12 words
The method of claim 12, wherein said filler metal consists of tungsten.
Claim 18
Dependent Claim
15 words
The method of claim 12, wherein said filler metal is deposited by chemical vapor deposition.
Claim 19
Dependent Claim
23 words
The method of claim 12, wherein said insulating layer includes at least 25% at of silicon and at least 40% at of oxygen.
Claim 20
Dependent Claim
24 words
The method of claim 12, wherein said step (b) etches at least some of said contact holes to have a greater depth than width.
Claim 21
Dependent Claim
14 words
The method of claim 12, wherein said insulating layer consists essentially of silicon oxide.
Claim 22
Dependent Claim
13 words
The method of claim 12, wherein said insulating layer comprises a silicate glass.
Claim 23
Dependent Claim
10 words
The method of claim 12, wherein said metallization comprises aluminum.
Claim 24
Dependent Claim
26 words
The method of claim 12, wherein said adhesion layer is selected from the group consisting of titanium, titanium nitride, and composites of titanium with titanium nitride.
Claim 25
Dependent Claim
206 words
An integrated circuit fabrication method, comprising the steps of: (a.) providing a substrate which includes an insulating layer, including at least 25% at of silicon and at least 40% at of oxygen, at a surface thereof; (b.) etching contact holes in desired locations of said insulating layer, at least some ones of said contact holes having a greater depth than width; (c.) depositing an adhesion layer comprising titanium on said insulating layer and into said contact holes; (d.) conformally depositing a filler metal overall; (e.) applying RF power to a controlled gas mixture to perform a first etch, which etches said filler metal preferentially with respect to said adhesion layer, and stopping said first etch when erosion of said adhesion layer is detected; (f.) applying RF power to a controlled gas mixture to perform a timed second etch, which etches said filler metal equally with said adhesion layer, until said filler metal has been totally removed outside said contact holes, but said adhesion layer remains in at least some locations; (g.) depositing a metallization layer overall; and (h.) patterning said metallization layer and said adhesion layer to implement a desired wiring pattern which includes connection to said filler metal in multiple ones of said contact holes.
Claim 26
Dependent Claim
206 words
An integrated circuit fabrication method, comprising the steps of: (a.) providing a substrate which includes an insulating layer, including at least 25% at of silicon and at least 40% at of oxygen, at a surface thereof; (b.) etching contact holes in desired locations of said insulating layer, at least some ones of said contact holes having a greater depth than width; (c.) depositing an adhesion layer comprising titanium on said insulating layer and into said contact holes; (d.) conformally depositing a filler metal overall; (e.) applying RF power to a controlled gas mixture to perform a first etch, which etches said filler metal preferentially with respect to said adhesion layer, and stopping said first etch when erosion of said adhesion layer is detected; (f.) applying RF power to a controlled gas mixture to perform a timed second etch, which etches said filler metal equally with said adhesion layer, until said filler metal has been totally removed outside said contact holes, but said adhesion layer remains in at least some locations; (g.) depositing a metallization layer overall; and (h.) patterning said metallization layer and said adhesion layer to implement a desired wiring pattern which includes connection to said filler metal in multiple ones of said contact holes.
Claim 27
Dependent Claim
19 words
The method of claim 23, wherein at least some ones of said contact holes make contact to said substrate.
Claim 28
Dependent Claim
26 words
The method of claim 23, wherein said substrate consists essentially of silicon, and at least some ones of said contact holes make contact to said substrate.
Claim 29
Dependent Claim
12 words
The method of claim 23, wherein said filler metal consists of tungsten.
Claim 30
Dependent Claim
15 words
The method of claim 23, wherein said filler metal is deposited by chemical vapor deposition.
Claim 31
Dependent Claim
14 words
The method of claim 23, wherein said insulating layer consists essentially of silicon oxide.
Claim 32
Dependent Claim
13 words
The method of claim 23, wherein said insulating layer comprises a silicate glass.
Claim 33
Dependent Claim
10 words
The method of claim 23, wherein said metallization comprises aluminum.
Claim 34
Dependent Claim
26 words
The method of claim 23, wherein said adhesion layer is selected from the group consisting of titanium, titanium nitride, and composites of titanium with titanium nitride.
Claim 35
Dependent Claim
191 words
A process for forming a metallization film over tungsten plugs, formed by defining and etching openings through a dielectric layer, depositing an adhesion layer of titanium nitride, depositing a tungsten layer on the adhesion layer and etching the tungsten until exposing the adhesion layer of titanium nitride over the surface of said dielectric layer under etch selectivity conditions of tungsten versus titanium nitride, thus leaving said plugs of tungsten into said openings and tungsten residues along discontinuities from planarity of said surface, comprising the additional steps of stopping said first etching step upon exposing said adhesion layer of titanium nitride; modifying said etch selectivity conditions by reducing etch selectivity sufficiently to produce also an etching of titanium nitride together with tungsten; performing a second etching step under these modified selectivity conditions for said residues of tungsten from said surface while simultaneously etching said tungsten plugs and said adhesion layer of titanium nitride, partially reducing the thickness of the latter; depositing a metallization layer over a residual layer of titanium nitride and over said tungsten plugs; and patterning a stack composed of said metallization layer and said residual layer of titanium nitride.
Claim 36
Dependent Claim
191 words
A process for forming a metallization film over tungsten plugs, formed by defining and etching openings through a dielectric layer, depositing an adhesion layer of titanium nitride, depositing a tungsten layer on the adhesion layer and etching the tungsten until exposing the adhesion layer of titanium nitride over the surface of said dielectric layer under etch selectivity conditions of tungsten versus titanium nitride, thus leaving said plugs of tungsten into said openings and tungsten residues along discontinuities from planarity of said surface, comprising the additional steps of stopping said first etching step upon exposing said adhesion layer of titanium nitride; modifying said etch selectivity conditions by reducing etch selectivity sufficiently to produce also an etching of titanium nitride together with tungsten; performing a second etching step under these modified selectivity conditions for said residues of tungsten from said surface while simultaneously etching said tungsten plugs and said adhesion layer of titanium nitride, partially reducing the thickness of the latter; depositing a metallization layer over a residual layer of titanium nitride and over said tungsten plugs; and patterning a stack composed of said metallization layer and said residual layer of titanium nitride.
Claim 37
Dependent Claim
42 words
A process as defined in claim 32, wherein said etch selectivity of tungsten versus titanium nitride during said first etching step is comprised between 30:1 and 15:1 and etch selectivity during said second etching step are reduced to within 15:1 and 1:10.
Claim 38
Dependent Claim
42 words
A process as defined in claim 33, wherein said first highly selective etching step is performed in a SF 6 plasma and said second etching step having a reduced selectivity is performed in a plasma of SF 6 and Cl 2 .
Claim 39
Dependent Claim
9 words
A product produced by the method of claim 1.
Claim 40
Dependent Claim
9 words
A product produced by the method of claim 12.
Claim 41
Dependent Claim
9 words
A product produced by the method of claim 32.
Claim 42
Dependent Claim
208 words
An integrated circuit fabrication method, comprising the steps of: (a.) providing a substrate which includes one or more semiconductor devices, with an insulating layer thereover which includes at least: 25% at of silicon and at least 40% at of oxygen; (b.) etching contact holes in desired locations of said insulating layer; (c.) depositing an adhesion layer on said insulating layer and into said contact holes, said adhesion layer consisting of a material selected from the group consisting of titanium, titanium nitride, and composites of titanium with titanium nitride; (d.) conformally depositing a filler metal comprising tungsten overall; (e.) performing a first unpatterned etch, which etches said filler metal preferentially with respect to said adhesion layer, until said adhesion layer is exposed but said filler metal has not yet been removed outside said contact holes; (f.) performing a second unpatterned etch, which etches said filler metal equally with said adhesion layer, until said filler metal has been totally removed outside said contact holes, but said adhesion layer remains in at least some locations; (g.) depositing a metallization layer overall; and (h.) patterning said metallization layer and said adhesion layer to implement a desired wiring pattern which includes connection to said filler metal in multiple ones of said contact holes.
Claim 43
Dependent Claim
208 words
An integrated circuit fabrication method, comprising the steps of: (a.) providing a substrate which includes one or more semiconductor devices, with an insulating layer thereover which includes at least: 25% at of silicon and at least 40% at of oxygen; (b.) etching contact holes in desired locations of said insulating layer; (c.) depositing an adhesion layer on said insulating layer and into said contact holes, said adhesion layer consisting of a material selected from the group consisting of titanium, titanium nitride, and composites of titanium with titanium nitride; (d.) conformally depositing a filler metal comprising tungsten overall; (e.) performing a first unpatterned etch, which etches said filler metal preferentially with respect to said adhesion layer, until said adhesion layer is exposed but said filler metal has not yet been removed outside said contact holes; (f.) performing a second unpatterned etch, which etches said filler metal equally with said adhesion layer, until said filler metal has been totally removed outside said contact holes, but said adhesion layer remains in at least some locations; (g.) depositing a metallization layer overall; and (h.) patterning said metallization layer and said adhesion layer to implement a desired wiring pattern which includes connection to said filler metal in multiple ones of said contact holes.
Claim 44
Dependent Claim
19 words
The method of claim 38, wherein at least some ones of said contact holes make contact to said substrate.
Claim 45
Dependent Claim
26 words
The method of claim 38, wherein said substrate consists essentially of silicon, and at least some ones of said contact holes make contact to said substrate.
Claim 46
Dependent Claim
12 words
The method of claim 38, wherein said filler metal consists of tungsten.
Claim 47
Dependent Claim
15 words
The method of claim 38, wherein said filler metal is deposited by chemical vapor deposition.
Claim 48
Dependent Claim
24 words
The method of claim 38, wherein said step (b) etches at least some of said contact holes to have a greater depth than width.
Claim 49
Dependent Claim
14 words
The method of claim 38, wherein said insulating layer consists essentially of silicon oxide.
Claim 50
Dependent Claim
13 words
The method of claim 38, wherein said insulating layer comprises a silicate glass.
Claim 51
Dependent Claim
10 words
The method of claim 38, wherein said metallization comprises aluminum.
Claim 52
Dependent Claim
13 words
The method of claim 38, wherein said second etch is a timed etch.
References Cited (Backward Citations)
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1998-04-17 | 1998-10-17 | 1999-04-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-04-17 | 2002-10-17 | 2003-04-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-04-17 | 2006-10-17 | 2007-04-18 | $7700.00 | Window Closed / Lapsed |