US6096640A
Expired / Lapsed
US
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Method of making a gate electrode stack with a diffusion barrier
Assignee: Micron Technology Inc
•
Filing: 1998-04-02
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Granted: 2000-08-01
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Expires: 2018-04-02
Abstract
Abstract Disclosed is a gate electrode stack structure that uses a refractory metal silicon nitride layer as a diffusion barrier. The gate electrode stack has several layers, including a gate oxide layer over the semiconductor substrate, a polysilicon layer over the gate oxide layer, and the diffusion barrier between the polysilicon layer and a layer of electrically conductive material above. The diffusion barrier, which is preferably composed of a substantially amorphous refractory metal silicon nitride such as tungsten silicon nitride, does not oxidize when an oxidation process is applied to the gate electrode stack. Moreover, the diffusion barrier substantially prevents diffusion of the electrically conductive material into the polysilicon during heating processes. The refractory metal silicon nitride maintains a bulk resistivity less than 2,000 microhm-cm, thereby preserving satisfactory conductivity in the gate electrode stack. A process for forming the gate electrode stack and diffusion barrier is also disclosed.
Inventors
- 👤 Yongjun Hu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 10:53
CPC Classifications
H; H10; H10D; H10D64/00; H10D64/01; H10D64/013; H10D64/01302; H10D64/01304; H10D64/01306; H10D64/01308; H10D64/01312; H10D64/60; H10D64/66; H10D64/661; H10D64/662; H10D64/664; Y; Y10; Y10S; Y10S257/00; Y10S257/915
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
58 words
A process for forming a structure on a semiconductor substrate, said process comprising: forming a layer of silicon-containing material over said semiconductor substrate; forming a first electrically conductive layer comprising both tungsten silicon nitride and of titanium silicon nitride over said layer of silicon-containing material; and forming a second electrically conductive layer over said first electrically conductive layer.
Claim 2
Dependent Claim
58 words
A process for forming a structure on a semiconductor substrate, said process comprising: forming a layer of silicon-containing material over said semiconductor substrate; forming a first electrically conductive layer comprising both tungsten silicon nitride and of titanium silicon nitride over said layer of silicon-containing material; and forming a second electrically conductive layer over said first electrically conductive layer.
Claim 3
Dependent Claim
38 words
A process as recited in claim 1, wherein said process further comprises heating said structure in an oxidizing atmosphere after forming said second electrically conductive layer, said first electrically conductive layer being substantially not oxidized by said heating.
Claim 4
Dependent Claim
24 words
A process as recited in claim 2, wherein said first electrically conductive layer has a bulk resistivity less than 2,000 microhm-cm after said heating.
Claim 5
Dependent Claim
55 words
A process as recited in claim 1, wherein said process further comprises heating said structure after forming said second electrically conductive layer, said first electrically conductive layer substantially preventing electrically conductive material of said second electrically conductive layer from diffusing through said first electrically conductive layer into said layer of silicon-containing material during said heating.
Claim 6
Dependent Claim
22 words
A process as recited in claim 4, wherein said structure has a sheet resistivity of less than 1.7 ohm/sq. after said heating.
Claim 7
Dependent Claim
23 words
A process as recited in claim 1, further comprising a dry etch for selectively removing a portion of said first electrically conductive layer.
Claim 8
Dependent Claim
121 words
A process for forming a structure on a semiconductor substrate, said process comprising: forming an oxide layer over a semiconductor substrate; forming a polysilicon layer over said oxide layer; forming a diffusion barrier over and in contact with said polysilicon layer, said diffusion barrier including a refractory metal silicon nitride material composed of both tungsten silicon nitride and of titanium silicon nitride; forming a refractory metal layer over and in contact with said diffusion barrier, said structure including said oxide layer, said polysilicon layer, said diffusion barrier, and said refractory metal layer; exposing a portion of said semiconductor substrate adjacent to said oxide layer; and heating both of said structure and said portion of said semiconductor substrate in an oxidizing atmosphere.
Claim 9
Dependent Claim
121 words
A process for forming a structure on a semiconductor substrate, said process comprising: forming an oxide layer over a semiconductor substrate; forming a polysilicon layer over said oxide layer; forming a diffusion barrier over and in contact with said polysilicon layer, said diffusion barrier including a refractory metal silicon nitride material composed of both tungsten silicon nitride and of titanium silicon nitride; forming a refractory metal layer over and in contact with said diffusion barrier, said structure including said oxide layer, said polysilicon layer, said diffusion barrier, and said refractory metal layer; exposing a portion of said semiconductor substrate adjacent to said oxide layer; and heating both of said structure and said portion of said semiconductor substrate in an oxidizing atmosphere.
Claim 10
Dependent Claim
60 words
A process as recited in claim 7, wherein said refractory metal silicon nitride material has a first bulk resistivity and a first density before said heating and has a second bulk resistivity and a second density after said heating, and wherein said first bulk resistivity is less than 2,000 microhm-cm and said second bulk resistivity is less than 2,000 microhm-cm.
Claim 11
Dependent Claim
19 words
A process as recited in claim 8, wherein said second bulk resistivity is less than said first bulk resistivity.
Claim 12
Dependent Claim
61 words
A process as recited in claim 7, wherein said refractory metal silicon nitride material has a first bulk resistivity and a first density before said heating and has a second bulk resistivity and a second density after said heating, and wherein said second density is greater than said first density and wherein said second bulk resistivity is less than 2,000 microhm-cm.
Claim 13
Dependent Claim
60 words
A process as recited in claim 7, wherein said heating comprises an oxidation process whereby both of said structure and said portion of said semiconductor substrate are exposed to an oxidizing atmosphere having a temperature in a range from about 700° C. to about 1100° C. for a period in a range from about 5 minutes to about 50 minutes.
Claim 14
Dependent Claim
56 words
A process as recited in claim 7, wherein heating both of said structure and said portion of said semiconductor substrate in said oxidizing atmosphere oxidizes said portion of said semiconductor substrate to form a layer of oxide on said portion of said semiconductor substrate that is in contact with said oxide layer over said semiconductor substrate.
Claim 15
Dependent Claim
32 words
A process as recited in claim 7, said oxide layer is substantially composed of silicon dioxide and said semiconductor substrate is substantially composed of monocrystalline silicon in contact with the oxide layer.
Claim 16
Dependent Claim
186 words
A process for forming a structure on a semiconductor substrate, said process comprising: forming a gate oxide layer over a semiconductor substrate; forming a polysilicon layer over said gate oxide layer; forming a diffusion barrier over and in contact with said polysilicon layer, said diffusion barrier including both tungsten silicon nitride and titanium silicon nitride and having a first bulk resistivity less than 2,000 microhm-cm; forming a tungsten layer over and in contact with said diffusion barrier, such that said structure includes said gate oxide layer, said polysilicon layer, said diffusion barrier, and said tungsten layer; exposing a portion of said semiconductor substrate adjacent to said gate oxide layer; and conducting an oxidation process whereby both of said structure and said portion of said semiconductor substrate are exposed to an oxidizing atmosphere having a temperature in a range from about 700° C. to about 1100° C. for a period in a range from about 5 minutes to about 50 minutes, whereby said portion of said semiconductor substrate is oxidized, said tungsten silicon nitride having a second bulk resistivity after said oxidation process less than 2,000 microhm-cm.
Claim 17
Dependent Claim
186 words
A process for forming a structure on a semiconductor substrate, said process comprising: forming a gate oxide layer over a semiconductor substrate; forming a polysilicon layer over said gate oxide layer; forming a diffusion barrier over and in contact with said polysilicon layer, said diffusion barrier including both tungsten silicon nitride and titanium silicon nitride and having a first bulk resistivity less than 2,000 microhm-cm; forming a tungsten layer over and in contact with said diffusion barrier, such that said structure includes said gate oxide layer, said polysilicon layer, said diffusion barrier, and said tungsten layer; exposing a portion of said semiconductor substrate adjacent to said gate oxide layer; and conducting an oxidation process whereby both of said structure and said portion of said semiconductor substrate are exposed to an oxidizing atmosphere having a temperature in a range from about 700° C. to about 1100° C. for a period in a range from about 5 minutes to about 50 minutes, whereby said portion of said semiconductor substrate is oxidized, said tungsten silicon nitride having a second bulk resistivity after said oxidation process less than 2,000 microhm-cm.
Claim 18
Dependent Claim
177 words
A process for forming a structure on a semiconductor substrate, said process comprising: forming a gate oxide layer over a semiconductor substrate; forming a polysilicon layer over said gate oxide layer; forming a diffusion barrier over and in contact with said polysilicon layer, said diffusion barrier including a refractory metal silicon nitride material composed of both tungsten silicon nitride and of titanium silicon nitride; forming a refractory metal layer over and in contact with said diffusion barrier, such that said structure includes said gate oxide layer, said polysilicon layer, said diffusion barrier, and said refractory metal layer; applying a dopant material to a portion of said semiconductor substrate, thereby forming a doped region of said semiconductor substrate and an adjacent undoped region of said semiconductor substrate; and heating both of said structure and said doped region of said semiconductor substrate, whereby a portion of said dopant material in said doped region diffuses into a portion of said undoped region, said structure having a first sheet resistance before said heating and a second sheet resistance after said heating.
Claim 19
Dependent Claim
177 words
A process for forming a structure on a semiconductor substrate, said process comprising: forming a gate oxide layer over a semiconductor substrate; forming a polysilicon layer over said gate oxide layer; forming a diffusion barrier over and in contact with said polysilicon layer, said diffusion barrier including a refractory metal silicon nitride material composed of both tungsten silicon nitride and of titanium silicon nitride; forming a refractory metal layer over and in contact with said diffusion barrier, such that said structure includes said gate oxide layer, said polysilicon layer, said diffusion barrier, and said refractory metal layer; applying a dopant material to a portion of said semiconductor substrate, thereby forming a doped region of said semiconductor substrate and an adjacent undoped region of said semiconductor substrate; and heating both of said structure and said doped region of said semiconductor substrate, whereby a portion of said dopant material in said doped region diffuses into a portion of said undoped region, said structure having a first sheet resistance before said heating and a second sheet resistance after said heating.
Claim 20
Dependent Claim
27 words
A process as recited in claim 15, wherein said first sheet resistance is less than 1.7 ohm/sq. and said second sheet resistance is less than 1.7 ohm/sq.
Claim 21
Dependent Claim
19 words
A process as recited in claim 16, wherein said second sheet resistance is less than said first sheet resistance.
Claim 22
Dependent Claim
61 words
A process as recited in claim 15, wherein said heating comprises an anneal process whereby both of said structure and said doped region of said semiconductor substrate are exposed to an annealing atmosphere having a temperature in a range from about 650° C. to about 1150° C. for a period in a range from about 10 seconds to about 90 seconds.
Claim 23
Dependent Claim
16 words
A process as recited in claim 15, wherein said heating is a rapid thermal heating process.
Claim 24
Dependent Claim
18 words
A process as recited in claim 15, wherein said heating comprises at least two of said heating processes.
Claim 25
Dependent Claim
142 words
A process for forming a structure on a semiconductor substrate, said process comprising: forming a gate oxide layer over said semiconductor substrate; forming a polysilicon layer over said gate oxide layer; forming a diffusion barrier over and in contact with said polysilicon layer, said diffusion barrier including a refractory metal silicon nitride material composed of both tungsten silicon nitride and of titanium silicon nitride; forming a refractory metal layer over and in contact with said diffusion barrier, such that said structure includes said gate oxide layer, said polysilicon layer, said diffusion barrier, and said refractory metal layer; forming silicate glass on said structure; and heating both of said structure and said silicate glass, thereby causing fluid displacement of a portion of said silicate glass, said structure having a first sheet resistance before said heating and a second sheet resistance after said heating.
Claim 26
Dependent Claim
142 words
A process for forming a structure on a semiconductor substrate, said process comprising: forming a gate oxide layer over said semiconductor substrate; forming a polysilicon layer over said gate oxide layer; forming a diffusion barrier over and in contact with said polysilicon layer, said diffusion barrier including a refractory metal silicon nitride material composed of both tungsten silicon nitride and of titanium silicon nitride; forming a refractory metal layer over and in contact with said diffusion barrier, such that said structure includes said gate oxide layer, said polysilicon layer, said diffusion barrier, and said refractory metal layer; forming silicate glass on said structure; and heating both of said structure and said silicate glass, thereby causing fluid displacement of a portion of said silicate glass, said structure having a first sheet resistance before said heating and a second sheet resistance after said heating.
Claim 27
Dependent Claim
27 words
A process as recited in claim 21, wherein said first sheet resistance is less than 1.7 ohm/sq. and said second sheet resistance is less than 1.7 ohm/sq.
Claim 28
Dependent Claim
19 words
A process as recited in claim 22, wherein said second sheet resistivity is less than said first sheet resistance.
Claim 29
Dependent Claim
14 words
A process as recited in claim 21, wherein said silicate glass is borophosphosilicate glass.
Claim 30
Dependent Claim
57 words
A process as recited in claim 21, wherein said heating comprises an anneal process whereby both of said structure and said silicate glass are exposed to an annealing atmosphere having a temperature in a range from about 650° C. to about 1150° C. for a period in a range from about 10 seconds to about 90 seconds.
Claim 31
Dependent Claim
16 words
A process as recited in claim 21, wherein said heating comprises a rapid thermal anneal process.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 2003-08-01 | 2004-01-31 | 2004-08-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2007-08-01 | 2008-01-31 | 2008-08-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2011-08-01 | 2012-01-31 | 2012-08-01 | $7700.00 | Window Closed / Lapsed |