title: Binary pseudo-random patterned structures for modulation transfer function calibration and resolution characterization of a full-field transmission soft x-ray microscope.
abstract: We present a modulation transfer function (MTF) calibration method based on binary pseudo-random (BPR) one-dimensional sequences and two-dimensional arrays as an effective method for spectral characterization in the spatial frequency domain of a broad variety of metrology instrumentation, including interferometric microscopes, scatterometers, phase shifting Fizeau interferometers, scanning and transmission electron microscopes, and at this time, x-ray microscopes. The inherent power spectral density of BPR gratings and arrays, which has a deterministic white-noise-like character, allows a direct determination of the MTF with a uniform sensitivity over the entire spatial frequency range and field of view of an instrument. We demonstrate the MTF calibration and resolution characterization over the full field of a transmission soft x-ray microscope using a BPR multilayer (ML) test sample with 2.8 nm fundamental layer thickness. We show that beyond providing a direct measurement of the microscope's MTF, tests with the BPRML sample can be used to fine tune the instrument's focal distance. Our results confirm the universality 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.
authors.affiliation: Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: V V
authors.initials: VV
authors.lastname: Yashchuk
authors.affiliation: Center for X-Ray Optics, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: P J
authors.initials: PJ
authors.lastname: Fischer
authors.affiliation: Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: E R
authors.initials: ER
authors.lastname: Chan
authors.affiliation: Advance Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA.
authors.forename: R
authors.initials: R
authors.lastname: Conley
authors.affiliation: Diablo Valley College, 321 Golf Club Road, Pleasant Hill, California 94523, USA.
authors.forename: W R
authors.initials: WR
authors.lastname: McKinney
authors.affiliation: KLA-Tencor Corp., 1 Technology Drive, Milpitas, California 95035, USA.
authors.forename: N A
authors.initials: NA
authors.lastname: Artemiev
authors.affiliation: National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: N
authors.initials: N
authors.lastname: Bouet
authors.affiliation: Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: S
authors.initials: S
authors.lastname: Cabrini
authors.affiliation: aBeam Technologies, Inc., Hayward, California 94541, USA.
authors.forename: G
authors.initials: G
authors.lastname: Calafiore
authors.affiliation: Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: I
authors.initials: I
authors.lastname: Lacey
authors.affiliation: aBeam Technologies, Inc., Hayward, California 94541, USA.
authors.forename: C
authors.initials: C
authors.lastname: Peroz
authors.affiliation: aBeam Technologies, Inc., Hayward, California 94541, USA.
authors.forename: S
authors.initials: S
authors.lastname: Babin