US6011646A
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US
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Method to adjust multilayer film stress induced deformation of optics
Assignee: EUV LLC
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Filing: 1998-02-20
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Granted: 2000-01-04
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Expires: 2018-02-20
Abstract
Abstract A buffer-layer located between a substrate and a multilayer for counteracting stress in the multilayer. Depositing a buffer-layer having a stress of sufficient magnitude and opposite in sign reduces or cancels out deformation in the substrate due to the stress in the multilayer. By providing a buffer-layer between the substrate and the multilayer, a tunable, near-zero net stress results, and hence results in little or no deformation of the substrate, such as an optic for an extreme ultraviolet (EUV) lithography tool. Buffer-layers have been deposited, for example, between Mo/Si and Mo/Be multilayer films and their associated substrate reducing significantly the stress, wherein the magnitude of the stress is less than 100 MPa and respectively near-normal incidence (5°) reflectance of over 60% is obtained at 13.4 nm and 11.4 nm. The present invention is applicable to crystalline and non-crystalline materials, and can be used at ambient temperatures.
Inventors
- 👤 Paul B. Mirkarimi
- 👤 Claude Montcalm
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 07:55
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/70; G03F7/70216; G03F7/70233; G02; G02B; G02B1/00; G02B1/10; G02B1/105; G02B1/14; G02B5/00; G02B5/20; G02B5/28; G02B5/283; G03F1/00; G03F1/22; G03F1/24; G03F7/70058; G03F7/7015; G03F7/70316; G03F7/708; G03F7/7095; G03F7/70958
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
59 words
In a device including a multilayer of high reflectance material and a substrate, the improvement comprising: means for adjusting or reducing the magnitude of stress in the multilayer with less than 5% reduction in reflectively comprising a buffer-layer located intermediate the multilayer and the substrate, the buffer-layer being composed of material having different stress characteristics than the multilayer material.
Claim 2
Dependent Claim
59 words
In a device including a multilayer of high reflectance material and a substrate, the improvement comprising: means for adjusting or reducing the magnitude of stress in the multilayer with less than 5% reduction in reflectively comprising a buffer-layer located intermediate the multilayer and the substrate, the buffer-layer being composed of material having different stress characteristics than the multilayer material.
Claim 3
Dependent Claim
16 words
The improvement of claim 1, wherein the magnitude of stress is less than about 100 MPa.
Claim 4
Dependent Claim
30 words
The improvement of claim 1, wherein said buffer-layer has a stress of sufficient magnitude and opposite in sign to the stress of said multilayer to cancel stress in the multilayer.
Claim 5
Dependent Claim
28 words
The improvement of claim 1, wherein said multilayer is selected from the group consisting of Mo/Si, Mo/Be, Mo/Y, Mo 2 C/Si, Mo/C, Mo/Sr, and Mo 2 C/Be multilayers.
Claim 6
Dependent Claim
24 words
The improvement of claim 1, wherein said buffer-layer is composed of one of Mo/Si, Mo/Be, Mo 2 C/Si, Mo 2 C/Be, a-Si, and a-C.
Claim 7
Dependent Claim
22 words
The improvement of claim 1, wherein said buffer-layer is composed of Mo/Si or Mo/Be, and wherein said multilayer is composed of Mo/Si.
Claim 8
Dependent Claim
23 words
The improvement of claim 1, wherein said buffer-layer is composed of a-Si, and wherein said multilayer is composed of either Mo/Be or Mo/Si.
Claim 9
Dependent Claim
31 words
The improvement of claim 1, wherein said buffer-layer and said multilayer are composed of Mo/Si, with the Mo/Si buffer-layer having a different Mo fraction than the Mo fraction in the multilayer.
Claim 10
Dependent Claim
25 words
The improvement of claim 1, wherein the Mo fraction in said buffer-layer is about 0.4 and said Mo fraction in said multilayer is about 0.8.
Claim 11
Dependent Claim
20 words
The improvement of claim 9, wherein the stress is adjusted by the Mo fraction in either multilayer or the buffer-layer.
Claim 12
Independent Claim
42 words
A method for reducing or negating multilayer film stress induced deformation of optics, comprising: providing an optic, forming a buffer layer on the optic, and forming a multilayer film on the buffer-layer, the multilayer film having different stress characteristics than the buffer-layer.
Claim 13
Independent Claim
42 words
A method for reducing or negating multilayer film stress induced deformation of optics, comprising: providing an optic, forming a buffer layer on the optic, and forming a multilayer film on the buffer-layer, the multilayer film having different stress characteristics than the buffer-layer.
Claim 14
Dependent Claim
21 words
The method of claim 11, wherein the buffer-layer is formed to provide a surface having less than 0.3 nm rms roughness.
Claim 15
Dependent Claim
32 words
The method of claim 11, wherein the buffer-layer is formed to have a stress of a magnitude and opposite in sign to cancel out deformation due to the stress in the multilayer.
Claim 16
Dependent Claim
26 words
The method of claim 11, wherein the buffer-layer is tunable to enable near-zero net stress so as to produce little or no deformation of the optic.
Claim 17
Dependent Claim
10 words
The method of claim 11, additionally including forming the optic.
Claim 18
Dependent Claim
32 words
The method of claim 11, wherein the optic is composed of material selected from the group, consisting of silicon, low thermal expansion glass-ceramics, quartz, float glass, ultra-low thermal expansion glass, and sapphire.
Claim 19
Dependent Claim
27 words
The method of claim 11, wherein the multilayer is formed of material selected from the group consisting of Mo/Si, Mo/Be, Mo 2 C/Si, and Mo 2 C/Be.
Claim 20
Dependent Claim
29 words
The method of claim 11, wherein the buffer-layer is formed of material selected from the group consisting of MoSi, Mo/Be, a-Si, Mo 2 C/Si, Mo 2 C/Be, and A-C.
Claim 21
Dependent Claim
34 words
The method of claim 11, wherein the buffer-layer and the multilayer are each formed from Mo/Si, and wherein the Mo/Si buffer-layer has a different Mo fraction than the Mo fraction in the Mo/Si multilayer.
Claim 22
Dependent Claim
22 words
The method of claim 11, wherein the multilayer is formed of Mo/Si, and wherein the buffer-layer is formed of Mo/Si or Mo/Be.
Claim 23
Dependent Claim
20 words
The method of claim 11, wherein the multilayer is formed of Mo/Be, and wherein the buffer-layer is formed of a-Si.
Claim 24
Dependent Claim
19 words
The method of claim 11, wherein the buffer-layer is adjustable in stress by increasing or decreasing the thickness thereof.
Claim 25
Dependent Claim
55 words
In an optic adapted for use in an extreme ultraviolet lithography tool and having a high reflectance multilayer, the improvement comprising: a buffer-layer positioned between the optic and the multilayer and constructed to at least reduce deformation of the optic due to stress in the multilayer, said buffer-layer having different stress characteristics than said multilayer.
Claim 26
Dependent Claim
55 words
In an optic adapted for use in an extreme ultraviolet lithography tool and having a high reflectance multilayer, the improvement comprising: a buffer-layer positioned between the optic and the multilayer and constructed to at least reduce deformation of the optic due to stress in the multilayer, said buffer-layer having different stress characteristics than said multilayer.
Claim 27
Dependent Claim
32 words
The improvement of claim 23, wherein said buffer-layer is smooth and has a stress of sufficient magnitude and opposite in sign to cancel out deformation due to the stress in the multilayer.
Claim 28
Dependent Claim
54 words
The improvement of claim 23, wherein said buffer-layer is selected from the group of material consisting of Mo/Si, Mo/Be, Mo 2 C/Si, Mo 2 C/Be, a-Si, and a-C, and wherein said multilayer is composed of material selected from the group consisting of Mo/Si, Mo/Be, Mo/Y, Mo 2 C/Si, Mo/Sr, Mo/C, and Mo 2 C/Be.
Claim 29
Independent Claim
61 words
A method for adjusting stress in a molybdenum containing multilayer of high reflectance material deposited on a substrate, including: forming a molybdenum containing buffer-layer intermediate the multilayer and the substrate the buffer-layer having different stress characteristics than the multilayer; and controlling the stress in the multilayer by adjusting the molybdenum fraction in at least one of the multilayers and the buffer-layer.
Claim 30
Independent Claim
61 words
A method for adjusting stress in a molybdenum containing multilayer of high reflectance material deposited on a substrate, including: forming a molybdenum containing buffer-layer intermediate the multilayer and the substrate the buffer-layer having different stress characteristics than the multilayer; and controlling the stress in the multilayer by adjusting the molybdenum fraction in at least one of the multilayers and the buffer-layer.
Claim 31
Dependent Claim
18 words
The method of claim 26, wherein the molybdenum containing multilayer and buffer-layer are composed of molybdenum and silicon.
References Cited (Backward Citations)
US5433988A
Cited
US5841584A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2003-01-03 | 2003-07-05 | 2004-01-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2007-01-03 | 2007-07-05 | 2008-01-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2011-01-03 | 2011-07-05 | 2012-01-04 | $7700.00 | Window Closed / Lapsed |