US5670426A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for reducing contact resistance
Assignee: Taiwan Semiconductor Manufacturing Co TSMC Ltd
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Filing: 1996-01-29
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Granted: 1997-09-23
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Expires: 2016-01-29
Abstract
Abstract A method for substantially improving the electrical characteristics of contact surfaces in contact holes and via holes that are formed in semiconductor substrates is disclosed. The method involves, in particular, the introduction of an "after-etch" process, subsequent to the application of prior art methods of "main-etch," "over-etch," and "soft-etch" that are employed in opening holes in semiconductors, in general. The said process uses an isotropic dry etch assisted by argon gas ions in such a way that the area of the contact surfaces are increased manyfold through the formation of three-dimensional structures. It is shown that the resulting electrical contact resistance of the surfaces is reduced, and therefore, improved substantially.
Inventors
- 👤 So Wen Kuo
- 👤 Chia-Shiung Tsai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 19:12
CPC Classifications
H; H10; H10D; H10D64/00; H10D64/01; H10D64/011; H10D64/0111; H10P; H10P70/00; H10P70/20; H10P70/23; H10P70/234
Claims Analysis
Total Claims: 55
Claim 1
Independent Claim
105 words
A method of forming an electrically enhanced contact surface in a contact hole on a semiconductor substrate comprising the steps of: providing a silicon substrate over which is formed a blanket oxide layer overlying regions including FET devices therein; performing a main-etch of said oxide layer through patterned photo-resist mask deposited on the oxidelayer to form contact holes; performing an over-etch of said oxide layer through said mask; performing soft-etch of exposed silicon in said contact holes through said mask; performing after-etch of said silicon through said mask thereby increasing the surface area of said silicon; and depositing metal in said holes to form contact-plugs.
Claim 2
Independent Claim
105 words
A method of forming an electrically enhanced contact surface in a contact hole on a semiconductor substrate comprising the steps of: providing a silicon substrate over which is formed a blanket oxide layer overlying regions including FET devices therein; performing a main-etch of said oxide layer through patterned photo-resist mask deposited on the oxidelayer to form contact holes; performing an over-etch of said oxide layer through said mask; performing soft-etch of exposed silicon in said contact holes through said mask; performing after-etch of said silicon through said mask thereby increasing the surface area of said silicon; and depositing metal in said holes to form contact-plugs.
Claim 3
Dependent Claim
13 words
The method of claim 1, wherein the main-etch is a dry plasma etch.
Claim 4
Dependent Claim
13 words
The method of claim 2, wherein the gas of said plasma is fluorinated.
Claim 5
Dependent Claim
21 words
The method of claim 2, wherein the temperature of said plasma is in between about 30° C. temperature to 80° C.
Claim 6
Dependent Claim
20 words
The method of claim 2, wherein the pressure of said plasma is in between about 5 mT to 20 mT.
Claim 7
Dependent Claim
20 words
The method of claim 2, wherein the power for said plasma is in between about 80 watts to 120 watts.
Claim 8
Dependent Claim
20 words
The method of claim 2, wherein the time of said plasma etch is in between about 90 to 120 seconds.
Claim 9
Dependent Claim
17 words
The method of claim 1, wherein the over-etch time is in between about 40 to 60 seconds.
Claim 10
Dependent Claim
11 words
The method of claim 1, wherein soft-etch is an isotropic etch.
Claim 11
Dependent Claim
18 words
The method of claim 9, wherein the time of the said isotropic etch is 30 to 50 seconds.
Claim 12
Dependent Claim
13 words
The method of claim 1, wherein the after-etch is a dry plasma etch.
Claim 13
Dependent Claim
13 words
The method of claim 11, wherein said plasma is ion-assisted with argon gas.
Claim 14
Dependent Claim
21 words
The method of claim 12, wherein the flow rate of said argon gas is in between about 100 to 250 sccm.
Claim 15
Dependent Claim
20 words
The method of claim 11, wherein the temperature of said plasma is in between about 30° C. to 100° C.
Claim 16
Dependent Claim
20 words
The method of claim 11, wherein the pressure of said plasma is in between about 700 mT to 800 mT.
Claim 17
Dependent Claim
20 words
The method of claim 11, wherein the power for said plasma is in between about 50 watts to 100 watts.
Claim 18
Dependent Claim
20 words
The method of claim 11, wherein the time of said plasma etch is in between about 90 to 130 seconds.
Claim 19
Independent Claim
105 words
A method of forming an electrically enhanced contact surface in a contact hole on a semiconductor substrate comprising the steps of: providing a silicon substrate over which is formed a blanket oxide layer overlying regions including bipolar devices therein; performing a main-etch of said oxide layer through patterned photo-resist mask deposited on the oxidelayer to form contact holes; performing an over-etch of said oxide layer through said mask; performing soft-etch of exposed silicon in said contact holes through said mask; performing after-etch of said silicon through said mask thereby increasing the surface area of said silicon; and depositing metal in said holes to form contact-plugs.
Claim 20
Independent Claim
105 words
A method of forming an electrically enhanced contact surface in a contact hole on a semiconductor substrate comprising the steps of: providing a silicon substrate over which is formed a blanket oxide layer overlying regions including bipolar devices therein; performing a main-etch of said oxide layer through patterned photo-resist mask deposited on the oxidelayer to form contact holes; performing an over-etch of said oxide layer through said mask; performing soft-etch of exposed silicon in said contact holes through said mask; performing after-etch of said silicon through said mask thereby increasing the surface area of said silicon; and depositing metal in said holes to form contact-plugs.
Claim 21
Dependent Claim
13 words
The method of claim 18, wherein the main-etch is a dry plasma etch.
Claim 22
Dependent Claim
13 words
The method of claim 19, wherein the gas of said plasma is fluorinated.
Claim 23
Dependent Claim
21 words
The method of claim 19, wherein the temperature of said plasma is in between about 30° C. temperature to 100° C.
Claim 24
Dependent Claim
20 words
The method of claim 19, wherein the pressure of said plasma is in between about 5 mT to 20 mT.
Claim 25
Dependent Claim
20 words
The method of claim 19, wherein the power for said plasma is in between about 80 watts to 120 watts.
Claim 26
Dependent Claim
20 words
The method of claim 19, wherein the time of said plasma etch is in between about 90 to 120 seconds.
Claim 27
Dependent Claim
17 words
The method of claim 18, wherein the over-etch time is in between about 40 to 60 seconds.
Claim 28
Dependent Claim
11 words
The method of claim 18, wherein soft-etch is an isotropic etch.
Claim 29
Dependent Claim
18 words
The method of claim 26, wherein the time of the said isotropic etch is 30 to 50 seconds.
Claim 30
Dependent Claim
13 words
The method of claim 18, wherein the after-etch is a dry plasma etch.
Claim 31
Dependent Claim
13 words
The method of claim 28, wherein said plasma is ion-assisted with argon gas.
Claim 32
Dependent Claim
20 words
The method of claim 28, wherein the temperature of said plasma is in between about 30° C. to 100° C.
Claim 33
Dependent Claim
20 words
The method of claim 28, wherein the pressure of said plasma is in between about 700 mT to 800 mT.
Claim 34
Dependent Claim
20 words
The method of claim 28, wherein the power for said plasma is in between about 50 watts to 100 watts.
Claim 35
Dependent Claim
20 words
The method of claim 28, wherein the time of said plasma etch is in between about 90 to 130 seconds.
Claim 36
Independent Claim
139 words
A method for fabricating a submicron semiconductor integrated IC device comprising: forming individual semiconductor devices within and on a semiconductor substrate; and forming a multilayer metallurgy structure over and connected to said devices to produce said IC semiconductor device; forming a photo-resist mask on a silicon dioxide layer already deposited over said devices; performing main-etch, over-etch, soft-etch on said oxide layer to form contact holes followed by after-etch where the soft-etch is performed on exposed silicon, and the after-etch increases the surface area of said silicon; depositing metal into said holes to form contact-plugs; further depositing metal to form interconnect layer; covering said metal layer with interlevel dielectric and then etching through the dielectric over a mask to form via holes; further depositing metal in said via holes to form via-plugs; further depositing metal to form another interconnect layer.
Claim 37
Independent Claim
139 words
A method for fabricating a submicron semiconductor integrated IC device comprising: forming individual semiconductor devices within and on a semiconductor substrate; and forming a multilayer metallurgy structure over and connected to said devices to produce said IC semiconductor device; forming a photo-resist mask on a silicon dioxide layer already deposited over said devices; performing main-etch, over-etch, soft-etch on said oxide layer to form contact holes followed by after-etch where the soft-etch is performed on exposed silicon, and the after-etch increases the surface area of said silicon; depositing metal into said holes to form contact-plugs; further depositing metal to form interconnect layer; covering said metal layer with interlevel dielectric and then etching through the dielectric over a mask to form via holes; further depositing metal in said via holes to form via-plugs; further depositing metal to form another interconnect layer.
Claim 38
Dependent Claim
13 words
The method of claim 34, wherein the main-etch is a dry plasma etch.
Claim 39
Dependent Claim
13 words
The method of claim 35, wherein the gas of said plasma is fluorinated.
Claim 40
Dependent Claim
21 words
The method of claim 35, wherein the temperature of said plasma is in between about 30° C. temperature to 80° C.
Claim 41
Dependent Claim
20 words
The method of claim 35, wherein the pressure of said plasma is in between about 5 mT to 20 mT.
Claim 42
Dependent Claim
20 words
The method of claim 35, wherein the power for said plasma is in between about 80 watts to 120 watts.
Claim 43
Dependent Claim
20 words
The method of claim 35, wherein the time of said plasma etch is in between about 90 to 120 seconds.
Claim 44
Dependent Claim
17 words
The method of claim 34, wherein the over-etch time is in between about 40 to 60 seconds.
Claim 45
Dependent Claim
11 words
The method of claim 34, wherein soft-etch is an isotropic etch.
Claim 46
Dependent Claim
18 words
The method of claim 42, wherein the time of the said isotropic etch is 30 to 50 seconds.
Claim 47
Dependent Claim
13 words
The method of claim 34, wherein the after-etch is a dry plasma etch.
Claim 48
Dependent Claim
13 words
The method of claim 44, wherein said plasma is ion-assisted with argon gas.
Claim 49
Dependent Claim
21 words
The method of claim 45, wherein the flow rate of said argon gas is in between about 100 to 250 sccm.
Claim 50
Dependent Claim
20 words
The method of claim 44, wherein the temperature of said plasma is in between about 30° C. to 100° C.
Claim 51
Dependent Claim
20 words
The method of claim 44, wherein the pressure of said plasma is in between about 700 mT to 800 mT.
Claim 52
Dependent Claim
20 words
The method of claim 44, wherein the power for said plasma is in between about 50 watts to 100 watts.
Claim 53
Dependent Claim
20 words
The method of claim 44, wherein the time of said plasma etch is in between about 90 to 130 seconds.
Claim 54
Dependent Claim
22 words
The method of claim 34, wherein the metal which is deposited in said contact holes is etched back to form the contact-plug.
Claim 55
Dependent Claim
19 words
The method of claim 34, wherein metal is deposited in said via holes to form the another interconnect layer.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-09-22 | 2001-03-24 | 2001-09-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-09-22 | 2005-03-24 | 2005-09-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-09-22 | 2009-03-24 | 2009-09-23 | $7700.00 | Window Closed / Lapsed |