Low energy Xe+ ion beam machining of ULE® substrates for EUVL projection optics – Evaluation of high-spatial frequency roughness

Endo, Hironori; Inaba, Takuro; Pahlovy, Shahjada A.; Miyamoto, Iwao

doi:10.1016/j.mee.2009.11.124

Cited by 8 publications

(3 citation statements)

References 11 publications

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“…Present IBF technology development is focusing on figuring process and the surface finish qualities, such as the surface roughness after figuring [5][6], how to obtain small size ion beam [6][7] and correct mid-frequency [7]. Besides, how to develop this deterministic technology for high slope surfaces is also the key problem to be solved, since this kind of components are playing more and more important roles in modern optical system, where the surface accuracy is required very high and becomes the critical factor responsible for system performances.…”

Section: Introductionmentioning

confidence: 99%

Three-Dimensional Surface Error Reconstruction and Ion Beam Figuring of Optical Hemisphere

Liao

Dai

Xie

et al. 2012

AMR

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This research is aiming at exploring a feasible machining method for ultra-high slope surface with deterministic figuring technology. We first successfully realize the nanometer-precision machining of optical hemispherical surface by using ion beam figuring (IBF) under the guidance of the reconstructed three-dimensional (3D) surface error. For figuring such a high-slope surface, we proposed some technical details, the modified algorithm for dwell time, the nonlinear developing method of surface error and the stitching machining technology, to address some important problems in process. Simultaneity a fused silica hemispherical surface is figured with our proposed method on the experimental installation IBF700-5V developed by ourselves. The root-mean-square (RMS) surface error of this sample is reduced from 19.6 nm to 9.6 nm after four iterations and about 37.8min. The experimental results indicate that IBF is a technique of high efficiency for the nanometer-precision machining of high-slope surface.

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Section: Introductionmentioning

confidence: 99%

Three-Dimensional Surface Error Reconstruction and Ion Beam Figuring of Optical Hemisphere

Liao

Dai

Xie

et al. 2012

AMR

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“…[19][20][21][22] In the case of the ULE Ò surface, the 0.2-10.0 keV Xe þ ion beam energy used to machine the substrate is lower than that for the Ar þ ion beam. [23][24][25] When a high energy (3.0-10.0 keV) Xe þ ion beam is used for figure error correction of the ULE Ò substrate, the HSFR at a machined depth of 50 nm (this value is greater than the figure error after mechanical polishing) becomes 0.18 nm rms. Moreover, the HSFR of the ULE Ò substrate machined by a Xe þ ion beam with energy below 0.7 keV at a machined depth of less than 50 nm become less than 0.08 nm rms.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, the HSFR of the ULE Ò substrate machined by a Xe þ ion beam with energy below 0.7 keV at a machined depth of less than 50 nm become less than 0.08 nm rms. 25) When the high energy (3.0-10 keV) ion beam is used for figure error correction, the substrates becomes rough. Therefore, we consider the figure error correction process with a combination of (1) a figuring process and (2) a smoothing process, and have proposed a low energy (0.2-3.0 keV) smoothing process to improve surface roughness by using a Xe þ ion beam as shown Fig.…”

Section: Introductionmentioning

confidence: 99%

Low Energy Xe⁺ Ion Beam Machining of the Ultralow Expansion Glass Substrates for Aspherical Extreme Ultraviolet Lithography Projection Optics

Endo

Yamada

Pahlovy

et al. 2011

Jpn. J. Appl. Phys.

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Aspherical substrates for extreme ultraviolet lithography (EUVL) optics require an ultrahigh shape accuracy of less than 0.15 nm rms and a high-spatial frequency roughness (HSFR; spatial wavelength: less than 1 µm) of 0.12 nm rms. Generally, the ultra low expansion glass (ULE®) substrate with HSFR of 0.06–0.08 nm rms can be produced by mechanical machining methods. However, it is difficult to obtain the shape accuracy of less than 0.12 nm rms using mechanical machining methods. Therefore, ion beam figuring (IBF) may be adapted to final shape correction of the substrates for the projection optics of EUVL tools. In this study, we investigated the HSFR and machining rate of the ULE® substrate machined by a 0.3–1.0 keV Xe+ ion beam at off normal ion incidence angles and obtained the following results: the HSFRs of the ULE® substrate machined by a 1.0 keV Xe+ ion beam at a ion incidence angle of lower than 30° and a 0.3–0.5 keV Xe+ ion beam at an ion incidence angle of 0–45° are below 0.12 nm rms, which is smaller than the required HSFR specification of EUVL projection optics. From our experimental result and discussion, we concluded that the scan fine beam and tilt target mode smoothing for processing of the ULE® substrate meets the required specification of the HSFR (0.12 nm rms) of hemispherical ULE® substrates of EUVL projection optics.

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Ion Beam Figuring and Smoothing

Rauschenbach

2022

Springer Series in Materials Science

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Low energy Xe+ ion beam machining of ULE® substrates for EUVL projection optics – Evaluation of high-spatial frequency roughness

Cited by 8 publications

References 11 publications

Three-Dimensional Surface Error Reconstruction and Ion Beam Figuring of Optical Hemisphere

Three-Dimensional Surface Error Reconstruction and Ion Beam Figuring of Optical Hemisphere

Low Energy Xe⁺ Ion Beam Machining of the Ultralow Expansion Glass Substrates for Aspherical Extreme Ultraviolet Lithography Projection Optics

Ion Beam Figuring and Smoothing

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Low energy Xe+ ion beam machining of ULE® substrates for EUVL projection optics – Evaluation of high-spatial frequency roughness

Cited by 8 publications

References 11 publications

Three-Dimensional Surface Error Reconstruction and Ion Beam Figuring of Optical Hemisphere

Three-Dimensional Surface Error Reconstruction and Ion Beam Figuring of Optical Hemisphere

Low Energy Xe+ Ion Beam Machining of the Ultralow Expansion Glass Substrates for Aspherical Extreme Ultraviolet Lithography Projection Optics

Ion Beam Figuring and Smoothing

Contact Info

Product

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About

Low Energy Xe⁺ Ion Beam Machining of the Ultralow Expansion Glass Substrates for Aspherical Extreme Ultraviolet Lithography Projection Optics