Patent US2632673A successfully refreshed from Google Patents.
Patent US5407698A successfully refreshed from Google Patents.
US5407698A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Deposition of tungsten
Assignee: Nortel Networks Ltd
•
Filing: 1992-04-30
•
Granted: 1995-04-18
•
Expires: 2012-04-30
Abstract
Abstract A method is provided for low pressure chemical deposition of tungsten and tungsten metallization for defining interconnects for an integrated circuit. A surface layer of tungsten is provided which has a low film stress and a smooth surface characterized by a low diffuse reflectivity and high specular reflectivity, to facilitate photo-lithography. Tungsten is deposited by reduction of WF6 with H2 and SiH4 in nitrogen. Control of the gas flow rates, pressure, temperature and H2/WF6 ratio in the reactive gas mixture provides for tailoring of the structure and characteristics of a deposited tungsten layer to provide high step coverage or a smooth surface for forming an overlying layer of tungsten which may be patterned photo-lithographically for defining interconnect. In order to provide metallization providing both good step coverage in via and contact holes and smooth surface for deposition of surface metallization, a two-stage tungsten deposition is provided.
Inventors
- 👤 Ismail T. Emesh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 04:08
CPC Classifications
C; C23; C23C; C23C16/00; C23C16/02; C23C16/06; C23C16/08; C23C16/14; H; H10; H10W; H10W20/00; H10W20/01; H10W20/031; H10W20/056
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
98 words
A method for chemical vapour deposition of tungsten for an integrated circuit, comprising: exposing a substrate to a mixture of reactive gases consisting of WF 6 , H 2 and a carrier gas consisting essentially of nitrogen, maintaining a pressure between 1 and 9 Torr, a deposition temperature between 430° C. and 500° C., and controlling the relative flow rates of H 2 and WF 6 to provide a H 2 /WF 6 flow rate ratio of between 5 and 30, the mixture of gases thereby depositing on the substrate a layer of tungsten having a smooth surface.
Claim 2
Independent Claim
98 words
A method for chemical vapour deposition of tungsten for an integrated circuit, comprising: exposing a substrate to a mixture of reactive gases consisting of WF 6 , H 2 and a carrier gas consisting essentially of nitrogen, maintaining a pressure between 1 and 9 Torr, a deposition temperature between 430° C. and 500° C., and controlling the relative flow rates of H 2 and WF 6 to provide a H 2 /WF 6 flow rate ratio of between 5 and 30, the mixture of gases thereby depositing on the substrate a layer of tungsten having a smooth surface.
Claim 3
Dependent Claim
36 words
A method according to claim 1 wherein the flow rate of WF 6 is maintained in the range 10 to 40 sccm and the reactive gas mixture includes up to 15 sccm of SiH 4 .
Claim 4
Dependent Claim
69 words
A method according to claim 1 wherein a first thickness of tungsten is deposited while maintaining a H 2 /WF 6 flow rate ratio between 6 and 9 to provide good step coverage on the substrate, and subsequently increasing the H 2 /WF 6 flow rate ratio to between 20 and 30, and depositing a second thickness of tungsten, thereby forming a layer of tungsten having a smooth surface.
Claim 5
Independent Claim
155 words
A method of chemical vapour deposition for forming a layer of tungsten for metallization for an integrated circuit, the method comprising: exposing the substrate to a reactive gas mixture consisting of WF 6 , H 2 , and a carrier gas, maintaining a pressure from several mTorr to 10 Torr, and a temperature between 430° C. and 500° C., and controlling the gas flow rates to provide from 10 to 40 sccm WF 6 and gas flow rate ratio of H 2 /WF 6 in the range 5 to 30, thereby depositing a layer of tungsten in at least two steps comprising: in a first step, selecting a carrier gas consisting essentially of an inert gas, and depositing a first thickness of tungsten having good step coverage on the substrate, and in a second step, after changing the carrier gas to consist essentially of nitrogen, depositing a second thickness of tungsten having a smooth surface
Claim 6
Independent Claim
155 words
A method of chemical vapour deposition for forming a layer of tungsten for metallization for an integrated circuit, the method comprising: exposing the substrate to a reactive gas mixture consisting of WF 6 , H 2 , and a carrier gas, maintaining a pressure from several mTorr to 10 Torr, and a temperature between 430° C. and 500° C., and controlling the gas flow rates to provide from 10 to 40 sccm WF 6 and gas flow rate ratio of H 2 /WF 6 in the range 5 to 30, thereby depositing a layer of tungsten in at least two steps comprising: in a first step, selecting a carrier gas consisting essentially of an inert gas, and depositing a first thickness of tungsten having good step coverage on the substrate, and in a second step, after changing the carrier gas to consist essentially of nitrogen, depositing a second thickness of tungsten having a smooth surface
Claim 7
Dependent Claim
65 words
A method according to claim 4, comprising, in the first step maintaining a H 2 /WF 6 flow rate ratio between 6 and 9, and in the second step, maintaining a pressure in the range from 1 to 9 Torr, and increasing the relative flow rate of hydrogen to provide a H 2 /WF 6 flow rate ratio in the range from 20 to 30.
Claim 8
Dependent Claim
24 words
A method according to claim 5 wherein in the first step the inert gas is selected from the group consisting of argon and helium.
Claim 9
Dependent Claim
18 words
A method according to claim 4 wherein the reactive gas mixture includes up to 15 sccm of silane.
Claim 10
Dependent Claim
38 words
A method according to claim 5 wherein the deposition temperature during deposition of the first thickness of tungsten is 430° C., and the deposition temperature during deposition of the second thickness of tungsten is increased to 480° C.
References Cited (Backward Citations)
US4517225A
Cited
JPS61198628A
Cited
US4617087A
Cited
US4741928A
Cited
US4923715A
Cited
US5211987A
Cited
US4749597A
Cited
US4777061A
Cited
US5028565A
Cited
US5175017A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 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 |