Discrepancies between roughness measurements obtained with phase-shifting and white-light interferometry

Rhee, Hyug-Gyo; Vorburger, Theodore V.; Lee, Jonathan W.; Fu, Joseph

doi:10.1364/ao.44.005919

Cited by 47 publications

(29 citation statements)

References 22 publications

(24 reference statements)

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“…[7][8][9][10][11][12][13][14][15][16][17][18][19] The effectiveness of a given method critically hinges on the appropriate choice of test surface. A successful test surface should be suitable for calibration over the entire instrumental field of view with a uniform sensitivity to the MTF over the entire spatial frequency range up to the Nyquist frequency of the instrument.…”

Section: Measured Psdmentioning

confidence: 99%

“…Additionally, in order to be used as a certified standard, the MTF test surface should satisfy the conditions of ease of specification, reproducibility, and repeatability; and the accuracy of the MTF calibration should have a reasonably low sensitivity to possible fabrication imperfections of the surface. Most of the common test patterns used in MTF measurements, including knife-edge sources (step height standards), [7][8][9][10][11] bar targets, 12 sinusoidal surfaces, 13 periodic and quasiperiodic patterns, [14][15][16] white noise patterns 17 and random reference specimens 15,18 fail to meet all of these requirements. For a comprehensive review of standard reference specimens, see Ref.…”

Section: Measured Psdmentioning

confidence: 99%

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Calibration of the modulation transfer function of surface profilometers with binary pseudo-random test standards: expanding the application range

et al. 2010

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A modulation transfer function (MTF) calibration method based on binary pseudo-random (BPR) gratings and arrays [Proc. SPIE 7077-7 (2007), Opt. Eng. 47(7), 073602-1-5 (2008)] has been proven to be an effective MTF calibration method for a number of interferometric microscopes and a scatterometer [Nucl. Instr. and Meth. A 616, 172-82 (2010]. Here we report on a significant expansion of the application range of the method. We describe the MTF calibration of a 6 inch phase shifting Fizeau interferometer. Beyond providing a direct measurement of the interferometer's MTF, tests with a BPR array surface have revealed an asymmetry in the instrument's data processing algorithm that fundamentally limits its bandwidth. Moreover, the tests have illustrated the effects of the instrument's detrending and filtering procedures on power spectral density measurements. The details of the development of a BPR test sample suitable for calibration of scanning and transmission electron microscopes are also presented. Such a test sample is realized as a multilayer structure with the layer thicknesses of two materials corresponding to BPR sequence. The investigations confirm the universal character of the method that makes it applicable to a large variety of metrology instrumentation with spatial wavelength bandwidths from a few nanometers to hundreds of millimeters.

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Section: Measured Psdmentioning

confidence: 99%

Section: Measured Psdmentioning

confidence: 99%

Calibration of the modulation transfer function of surface profilometers with binary pseudo-random test standards: expanding the application range

et al. 2010

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“…It also provides a measure of the system MTF averaged over the entire extent of the aperture, rather than just in a very localized region around the height discontinuity of the single step artifact. 12,13 Particular methods for generation of maximum-length pseudo-random sequences [14][15][16] Similar to the requirement for maximum duty cycle of a pseudo-random chopper, the BPR grating has to be generated with a maximum filling factor for an improved signal-to-noise ratio of the PSD spectra of the test surface. The mathematical term for such a sequence is "maximumlength pseudo-random sequence" (MLPRS).…”

Section: Binary Pseudo-random Grating Propertiesmentioning

confidence: 99%

Binary pseudorandom grating standard for calibration of surface profilometers

2008

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We suggest and describe the use of a binary pseudo-random (BPR) grating as a standard test surface for measurement of the modulation transfer function (MTF) of interferometric microscopes. Knowledge of the MTF of a microscope is absolutely necessary to convert the measured height distribution of a surface undergoing metrology into an accurate power spectral density (PSD) distribution. For an 'ideal' microscope with an MTF function independent of spatial frequency out to the Nyquist frequency of the detector array with zero response at higher spatial frequencies, a BPR grating would produce a flat 1D PSD spectrum, independent of spatial frequency. For a 'real' instrument, the MTF is found as the square root of the ratio of the PSD spectrum measured with the BPR grating to the 'ideal', spatial frequency independent, PSD spectrum. We present the results from a measurement of the MTF of Micromap TM -570 interferometric microscope demonstrating a high efficiency for the calibration method.

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“…45,46 Reliability of the PSD data for these and other applications depends on experimental methods available for comprehensive characterization and calibration of the spatial frequency response of the metrology instruments in use. [47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65] There are also problems inherent in the statistical description of surface metrology data that we discuss in the next section.…”

Section: Introductionmentioning

confidence: 99%

Reliable before-fabrication forecasting of expected surface slope distributions for x-ray optics

Yashchuk

2011

SPIE Proceedings

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Numerical simulation of the performance of new beamlines and those under upgrade requires sophisticated and reliable information about the expected surface slope and height distributions of planned x-ray optics before they are fabricated. Obtaining such information should be based on the metrology data measured from existing mirrors that are made by the same vendor and technology; but, generally, with different sizes, slope and height rms variations. In this work, we demonstrate a method for highly reliable forecasting of the expected surface slope distributions of the prospective x-ray optics. The method is based on an autoregressive moving average (ARMA) modeling of the slope measurements with a limited number of parameters. With the found parameters of the ARMA model, the surface slope profile of an optic with the newly desired specification can reliably be forecast. We demonstrate the high accuracy of this type of forecasting by comparing the power spectral density distributions of the measured and forecast slope profiles.

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Discrepancies between roughness measurements obtained with phase-shifting and white-light interferometry

Cited by 47 publications

References 22 publications

Calibration of the modulation transfer function of surface profilometers with binary pseudo-random test standards: expanding the application range

Calibration of the modulation transfer function of surface profilometers with binary pseudo-random test standards: expanding the application range

Binary pseudorandom grating standard for calibration of surface profilometers

Reliable before-fabrication forecasting of expected surface slope distributions for x-ray optics

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