Phase-measuring interferometry using extreme ultraviolet radiation

Bjorkholm, J. E.; MacDowell, Alastair A.; Wood, O. R.; Tan, Zhengquan; LaFontaine, Bruno; Tennant, D. M.

doi:10.1116/1.588279

Cited by 33 publications

(19 citation statements)

References 1 publication

(1 reference statement)

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“…However, at shorter wavelengths, the implementation is more complicated due to the lack of high-efficiency optics. Common path interferometers, such as the shear interferometer [25] and the point-diffraction interferometer (PDI) [7], were demonstrated at EUV wavelengths for high-resolution metrology. Although the standard metrology schemes that use a single interferogram are very effective, these methods have several limitations.…”

Section: Introductionmentioning

confidence: 99%

Design of a phase-shifting interferometer in the extreme ultraviolet for high-precision metrology

2014

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The design of a phase-shift interferometer in the extreme ultraviolet (EUV) is described. The interferometer is expected to achieve a significantly higher precision as compared with similar instruments that utilize lasers in the visible range. The interferometer's design is specifically adapted for its utilization with a table top pulsed capillary discharge EUV laser. The numerical model evaluates the errors in the interferograms and in the retrieved wavefront induced by the shot-to-shot fluctuations and pointing instabilities of the laser.

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Section: Introductionmentioning

confidence: 99%

Design of a phase-shifting interferometer in the extreme ultraviolet for high-precision metrology

2014

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“…1,2,3 In particularly, the group of the Lawrence Berkeley National Laboratory enthusiastically studied atwavelength wavefront metrology including applications to two practical four-mirror optics 4,5 and an optic with a high numerical aperture (NA) of 0. 3.…”

Section: Introductionmentioning

confidence: 99%

EUV wavefront measurement of six-mirror optics using EWMS

Sugisaki¹,

Okada²,

Zhu³

et al. 2008

SPIE Proceedings

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The wavefront measurements have been performed with the EUV Wavefront Metrology System (EWMS) for the first time using a prototype projection optic as a test optic. The wavefronts of the test optic was measured at the five positions in the exposure field with the Digital Talbot Interferometer (DTI). The RMS magnitude of the wavefront errors ranged from 0.71 λ (9.58 nm) to 1.67 λ (22.75 nm). The results obtained with the DTI were compared to those with the Cross Grating Lateral Shearing Interferometer (CGLSI). As a result of a repeatability assessment, it was found that the EWMS can stably measure the wavefronts of the test optic. Additionally, unwrapping of the phase map was found to be related to the precision of the measurement.

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“…Calibrating the interferometer to here.Point sources where rm S the maximum radial (lateral) extent of the measurement at the mixing plane (all aberration magnitudes presented here are defined as zero-topeak values unless otherwise stated). Equation(2) can be rewritten in terms of NA and simplified using the small angle approximation yielding, Mixing Measurement geometry leading to systematic coma. Geometric coma induced error in waves as a function ofNA (s = 4.5 jim).…”

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confidence: 99%

Characterization of the accuracy of EUV phase-shifting point diffraction interferometry

Naulleau

Goldberg²,

Chang

et al. 1998

SPIE Proceedings

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The phase-shifting point diffraction interferometer (PS/PDI) has recently been developed and implemented at Lawrence Berkeley National Laboratory to meet the significant measurement challenge of characterizing extreme ultraviolet (EUV) projection lithography systems. Here progress on the characterization of the PSIPDI accuracy is presented. Two major classes of errors affect the accuracy of the interferometer: the first being systematic effects arising from the measurement geometry, and the second being random and systematic errors caused by an imperfect reference wave. In order to characterize these contributions and calibrate the interferometer, a null test is required. This null test also serves as a measure of the absolute accuracy of the interferometer. Experimental results demonstrating a systematic-enor-limited accuracy of 0.004 waves (21250 or 0.05 nm at X = 13.4 nm) is reported.

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Phase-measuring interferometry using extreme ultraviolet radiation

Abstract: Si nanostructures fabricated by electron beam lithography combined with image reversal process using electron cyclotron resonance plasma oxidation

Cited by 33 publications

References 1 publication

Design of a phase-shifting interferometer in the extreme ultraviolet for high-precision metrology

Design of a phase-shifting interferometer in the extreme ultraviolet for high-precision metrology

EUV wavefront measurement of six-mirror optics using EWMS

Characterization of the accuracy of EUV phase-shifting point diffraction interferometry

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