Narrow Band Mo/Si Multilayers with Thick Si Structures Tetsuo Harada*, Toshihide Tsuru, Tadashi Hatano and Masaki Yamamoto Research Center for Soft X-ray Microscopy, Institute of Multidisciplinary Research for Advanced Materials, Tohoku University e-mail: [email protected]Narrow band M/Si multilayers for 13.5 nm wavelength were designed and fabricated. The design concept for a narrow band multilayers is to increase the total thickness of effective layers in reflection than the needed temporal coherence length. The multilayers have thick Si structures, because Si are more transparent than Mo. The bandwidth of Mo (2.5 nm)/ Si (25.1 nm) multilayers using forth order Bragg reflection was 0.13 nm. Abstract Fourth International Extreme Ultra Violet Lithography (EUVL) Symposium 07-09 November 2005 San Diego, California
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Fourth International Extreme Ultra Violet Lithography ...euvlsymposium.lbl.gov/pdf/2005/poster/2-ML-03 Harada_TohokuU Poster.pdfThe island structure could be generated. The samples
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Narrow Band Mo/Si Multilayerswith Thick Si Structures
Tetsuo Harada*, Toshihide Tsuru, Tadashi Hatano and Masaki YamamotoResearch Center for Soft X-ray Microscopy,
Institute of Multidisciplinary Research for Advanced Materials, Tohoku University
Narrow band M/Si multilayers for 13.5 nm wavelength were designed and fabricated. The design concept for a narrow band multilayers is to increase the total thickness of effective layers in reflection than the needed temporal coherence length. The multilayers have thick Si structures, because Si are more transparent than Mo. The bandwidth of Mo (2.5 nm)/ Si (25.1 nm) multilayers using forth order Bragg reflection was 0.13 nm.
Abstract
Fourth International Extreme Ultra Violet Lithography (EUVL) Symposium
The reflectance of low γ Mo/Si multilayers ( m > 1 ) and the standard Mo/Si multilayer.
Soft X-ray Performance
The reflection spectrum were measured with synchrotron radiation at BL-12A, the Photon Factory using p-polarized light.
γ = 0.36
0.140.09
0.03
m = 1st
2nd
3rd
4th
8th
The reflectance of the fundamental low γ Mo/Si multilayers ( m = 1 ).
The wavelength of peak reflection were not constant for using the same deposition rate as the sample #1. The structure of the interfaces are not the same as
standard multilayer (sample #1).
The wavelength of peak reflection were almost the same as calculations, the remaining difference
being due to the instability of the deposition rate.
0.20
0
10
20
30
40
50
60
70
0 20 40 60 80 100 120 140 160
Si/Si3N4
#9, 8th, 0.05
#8, 4th, 0.09
#7, 3rd, 0.12
#6, 2nd, 0.18
#5, 1st, 0.03
#3, 1st, 0.14
#4, 1st, 0.09
#2, 1st, 0.20
λ/∆λ
Ref
lect
ance
(%)
#1, 1st, 0.36
Si/B4C
The sample No. #, m, γ
Discussion
The relation of the resolving power λ/∆λ and reflectance of the narrow band multilayers, the fundamental low γ multilayers (●), the low γ multilayers of constant Mo layer thickness (∆) and the
multilayers of low Z pair (■).
R ~ 9 %, λ/ ∆λ ~ 96dMo ~ 0.2 nm (too thin !)The island structure could be generated.
The samples #5, #8, #9 have good resolving power λ/ ∆λ.
Conclusion• The low γ multilayers were designed and deposited.• The low γ multilayer of m = 1, γ = 0.03, λ/ ∆λ has too thin Mo layer thickness.• The low γ multilayer of m = 4 has a good resolving power of λ/ ∆λ ~ 100. The layer interface structures will be stable, because the Mo layer thickness was 2.5 nm same as standard multilayer.
Target λ/ ∆λ
sample #5
sample #8
R ~ 10 %, λ/ ∆λ ~ 104The reflectance would be high.(comparison of the samples #7, #9)
sample #9R ~ 11 %, λ/ ∆λ ~ 150The coating was peeled for its stress.Si layers are under a strong compressive stress.