Novel aberration monitor for optical lithography

Dirksen, Peter; Juffermans, Casper A. H.; Pellens, Rudy J. M.; Maenhoudt, Mireille; Bisschop, Peter De

doi:10.1117/12.354385

Cited by 29 publications

(12 citation statements)

References 5 publications

(5 reference statements)

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“…Numerous methods have been demonstrated enabling print-based quantitative aberration extraction [9][10][11]; however, these methods typically rely on the use of phase shift masks and/or the ability to print at the diffraction limit of the optic.…”

Section: Measurement Methodsmentioning

confidence: 99%

Lithographic characterization of low-order aberrations in a 0.3-NA EUV microfield exposure tool

Naulleau

Cain

Dean³

et al. 2006

SPIE Proceedings

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Although tremendous progress has been made in the crucial area of fabrication of extreme ultraviolet (EUV) projection optics, the realization diffraction-limited high numerical aperture (NA) optics (above 0.2 NA) remains a concern. The highest NA EUV optics available to date are the 0.3-NA Microfield Exposure Tool (MET) optics used in an experimental exposure station at Lawrence Berkeley National Laboratory [1] and commercial METs [2] at Intel and SEMATECH-North. Even though these optics have been interferometrically demonstrated to achieve diffraction-limited wavefront quality, the question remains as to whether or not such performance levels can be maintained after installation of the optics into the exposure tool.Printing-based quantitative aberration measurements provide a convenient mechanism for the characterization of the optic wavefront error in the actual lithography tool. We present the lithographic measurement of low-order aberrations in the Berkeley MET tool, including a quantitative measurement of astigmatism and spherical error and a qualitative measurement of coma. The lithographic results are directly compared to interferometry results obtained from the same optic. Measurements of the Berkeley MET indicate either an alignment drift or errors in the interferometry on the order of 0.5 to 1 nm.

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Section: Measurement Methodsmentioning

confidence: 99%

Lithographic characterization of low-order aberrations in a 0.3-NA EUV microfield exposure tool

Naulleau

Cain

Dean³

et al. 2006

SPIE Proceedings

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“…Examples known to the authors are through-focus patterning of phase dots by Dirsken et. al, 2 patterning of Zernike Fourier transform targets by Robins et. al., 3 and patterning of coma targets by Nomura et.…”

Section: Motivationmentioning

confidence: 99%

MOSAIC: a new wavefront metrology

Anderson

Naulleau

2009

Metrology, Inspection, and Process Control for Microlithography XXIII

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MOSAIC is a new wavefront metrology that enables complete wavefront characterization from print or aerial image based measurements. Here we describe MOSAIC and verify its utility with a model-based proof of principle.Keywords: MOSAIC, aberration, wavefront, curvature, metrology, coherence, EUV MOTIVATIONThe manufacturing of high performance semiconductors requires routine monitoring of aberrations in exposure tool optics to ensure that diffraction-limited imaging remains the status quo and optical proximity correction strategies can be maintained. There are currently several metrologies devoted to this task.One metrology in widespread use today is an integrated lateral shearing interferometer (LSI) developed by ASML branded with the name ILIAS TM .1 There are also a handful of print-based tests in use that enable the quantification of specific aberrations, i.e., astigmatism, spherical error, or coma by imaging engineered mask features. Examples known to the authors are through-focus patterning of phase dots by Dirsken et. al, all of which require the ability to pattern at the diffraction limit of the imaging optic. Finally, there is another class of print-based tests that use through focus patterning of vertical, horizontal, and oblique grating patterns to quantify astigmatism 5, 6 and spherical error. 7As the industry progresses towards EUV lithography, integrated metrologies become increasingly difficult to implement. Moreover, print-based methods relying on diffraction-limited resist performance are hampered by the realities of resist limitations. Through-focus print-based techniques, however, have the ability to bypass resist limitations. Here we present a new wavefront metrology technique, MOSIAC (metrology of optical system aberrations by incoherent curvature sensing), which is a generalization of previously described through focus methods and enables complete * wavefront recovery from print or aerial image based measurements.While the above discussion has been centralized to the topic of lithography (the original motivation for our work), we would would like to point out that MOSAIC is applicable to the broader context of all optical systems requiring routine wavefront characterization where it is impractical to remove the optics from the tool assembly for testing. MOSAIC GoalsMOSAIC was designed with several goals in mind: (1) complete wavefront characterization, (2) simple integration into lithographic tools, (3) scalable to any numerical aperture (NA), and (4) at wavelength. MOSAIC, as you will see, satisfies all of the above criteria.

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“…Published by sensor (TIS) at multiple illumination settings) [6,7], and Nikon's Z37 AIS (Aerial Image Sensor) [8,9], aberration ring test [10,11] and phase wheel method [12].…”

Section: Osamentioning

confidence: 99%

Even aberration measurement of lithographic projection optics based on intensity difference of adjacent peaks in alternating phase-shifting mask image

et al. 2010

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This paper proposes an in-situ technique for measuring even aberration of lithographic projection optics. By using Hopkins theory of partial coherent imaging and thick-mask model, the linear relationship between intensity difference of adjacent peaks in alternating phase shifting mask (Alt-PSM) image and even aberration is established by equations and verified by numerical results. The sensitivity of measuring even aberration of lithographic projection optics based on this linear relationship is analyzed, and the measurement mark is designed accordingly. The measurement performance of the present technique is evaluated using lithographic OSA Published bysimulator PROLITH, which shows the present technique is capable of measuring even aberration of lithographic projection optics with ultrahigh measurement accuracy.

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Novel aberration monitor for optical lithography

Cited by 29 publications

References 5 publications

Lithographic characterization of low-order aberrations in a 0.3-NA EUV microfield exposure tool

Lithographic characterization of low-order aberrations in a 0.3-NA EUV microfield exposure tool

MOSAIC: a new wavefront metrology

Even aberration measurement of lithographic projection optics based on intensity difference of adjacent peaks in alternating phase-shifting mask image

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