Beamline Optics Research Articles

A Multilayer-Coated Reflection Mirror for Microfabrication

We propose a multilayer-coated mirror for the first mirror of a beamline. Calculated reflectivities of over 80% for B4C/W and C/Ni constant d-spacing multilayer-coated mirrors are obtained at 6 keV. Moreover, by using the constant d-spacing multilayer-coated mirror, a monochromatic light source with high reflectivity and high resolution is obtained at the glancing angle of 1.5°. Furthermore, it is determined that a graded d-spacing multilayer-coated mirror, i.e., a supermirror, is effective in this photon energy region since the half-width at half-maximum of the reflectivity increases. A multilayer-coated reflection mirror for beamline optics is promising for applications in microfabrication and structure analysis of materials.

A simple accurate method of alignment of beamline optics with the use of EUV multilayer polarizers.

A simple alignment method is proposed, which enables the alignment of beamline optics of a bending section accurately, relying on the linear state of polarization of synchrotron orbital radiation rather than the beam intensity. The method utilizes extreme UV (EUV) multilayers as a compact polarization monitor detecting unwanted vertical polarization components. The proposed method was found to be far more sensitive than that relying on the maximum intensity. Another advantage is the insensitivity to surface contamination, such as an irradiation mark on the mirror degrading reflectance. A design example is presented for use around a photon energy of 370 eV along with an experimental example at a photon energy of 97 eV.

New beamline optics for the effective use of a wiggler beam.

A hard X-ray beamline, BL13A, has been constructed for precision diffraction experiments conducted downstream of the multipole wiggler MPW#13 at the Photon Factory. The BL13A line can be used along with the main beamline, BL13B, which accepts the central 4 mrad of the 5 mrad horizontal fan. BL13A uses the remaining horizontal off-axis beam. The beam is diffracted by a double-crystal monochromator which uses asymmetric (422) diffraction with a horizontal diffraction vector. A monochromatic beam with 33.5 keV photon energy is directed to a precision goniometer. Good beam stability and high intensity were obtained.

Design of beamline optics for EUVL.

The design of front-end collimating optics for extreme-ultraviolet lithography (EUVL) is reported. For EUVL, collimating optics consisting of a concave toroidal mirror and a convex toroidal mirror can achieve shorter optical path lengths than collimating optics consisting of two concave toroidal mirrors. Collimating optics consisting of a concave toroidal mirror and a convex toroidal mirror are discussed. The design of collimating optics for EUVL beamlines based on ray-tracing studies is described.

High precision, low cost mask for deep x-ray lithography

The precision of transferred patterns are highly dependent on the quality of the mask in deep x-ray lithography. Many parameters, such as the critical energy of the synchrotron light, beamline optics and even the microstructure to be exposed should be considered in mask design. In this paper, the design rules and the boundary conditions for deep x-ray mask are discussed in general. The method of making a precision, multilayer mask using UV lithography technique is also described.

Two-dimensional X-ray microfocusing using a curved crystal Bragg-Fresnel lens

A two-dimensional focusing element based on a curved crystal Bragg-Fresnel lens was designed and successfully tested in the X-ray energy range of 15–20 keV on the Optics Beamline at the ESRF. A 4.5 × 9.1 μm 2 wide focal spot was observed at 17.2 keV. The intensity in the focal spot was two orders of magnitude higher with respect to a flat linear Bragg-Fresnel lens.

14] Overview of synchrotron radiation and macromolecular crystallography

Publisher Summary Synchrotron radiation (SR) is widely used in a variety of macromolecular crystallography applications. These include measurement of the highest possible resolution data, the study of large unit cells, the acquisition of data from crystals too small to study by other methods, the use of anomalous dispersion effects for phase determination, and time-resolved studies. Advanced instrumentation for protein and virus crystallography and very active facility support have been established at a large number of SR facilities; this includes beamline optics (the monochromator and focusing mirror that deliver an X-ray beam to the specimen, especially tailored for these measurements), as well as detectors and data-acquisition instrumentation. For dynamic studies, apparatus is needed to stimulate or perturb a sample (e.g., laser flash) and monitor the effects of this stimulation. Novel crystallographic data-collection methods are discussed in this chapter. The properties of synchrotron radiation can be described in terms of the well-defined quantities of high flux (large number of photons), high brightness (well collimated), high brilliance (small source size and well collimated), tunable, polarized, defined time structure (fine time resolution), and exactly calculable spectra.

Soft X-Ray Optics. Development of Multilayer Supermirror.

The recent progress of multilayers makes it possible to construct variety of optical systems used in the wavelength region 30-0.01nm. Especially a depth-graded multilayer, so called supermirror, has a great advantage to get high reflectivity in the wide energy band for hard x-rays. The design, fabrication and characterization of supermirror are going on to apply for synchrotron radiation beamline optics, x-ray telescope and x-ray microscope. At present reflectivity of Pt/C supermirror is obtained to be 20-30% in 27-40keV region at the incidence angle of 0.3deg..

Characterization of thermal distortion effects on beamline optics for EUV interferometry and soft x-ray microscopy

This study analyzes synchrotron radiation heat loading effects on optical components of beamline BL12.0 for EUV interferometry and soft x-ray microscopy at the Advanced Light Source (ALS). Newly developed indirect side-cooled beamline optics were considered, and the resulting surface distortion of mirrors and grating indicates that there is no significant degradation of beamline performance in spectral resolution or throughput. Also analyzed are the effects of heat loading on end-station components, such as Fresnel zone plates, transmission gratings, masks and membranes. Experimental results of heat loaded membranes are presented as well in this writing.

Experience with ray-tracing simulations at the European Synchrotron Radiation Facility (invited)

The ESRF is the first operational third-generation synchrotron radiation hard-x-ray source. Since the beginning of its construction (1988), the ray-tracing technique proved to be an essential computer tool for beamline optics design. The optical systems of most beamlines have been simulated by ray tracing in order to optimize the optics, fully understand their properties, and check if operation performances were as expected. In this paper, a short compilation of the experience with ray tracing and optics simulation codes at the ESRF, as well as some other in-house developments, is presented.

Interferometry using undulator sources (invited, abstract)

Optical systems for extreme ultraviolet (EUV) lithography need to use optical components with subnanometer surface figure error tolerances to achieve diffraction-limited performance [M.D. Himel, in Soft X-Ray Projection Lithography, A.M. Hawryluk and R.H. Stulen, eds. (OSA, Washington, D.C., 1993), 18, 1089, and D. Attwood et al., Appl. Opt. 32, 7022 (1993)]. Also, multilayer-coated optics require at-wavelength wavefront measurement to characterize phase effects that cannot be measured by conventional optical interferometry. Furthermore, EUV optical systems will additionally require final testing and alignment at the operational wavelength for adjustment and reduction of the cumulative optical surface errors. Therefore, at-wavelength interferometric measurement of EUV optics will be the necessary metrology tool for the successful development of optics for EUV lithography. An EUV point diffraction interferometer (PDI) has been developed at the Center for X-Ray Optics (CXRO) and has been already in operation for a year [K. Goldberg et al., in Extreme Ultra Lithography, D.T. Attwood and F. Zernike, eds. (OSA, Washington, D.C., 1994), K. Goldberg et al., Proc. SPIE 2437, to be published, and K. Goldberg et al., J. Vac. Sci. Technol. B 13, 2923 (1995)] using an undulator radiation source and coherent optics beamline at the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory. An overview of the PDI interferometer and some EUV wavefront measurements obtained with this instrument will be presented. In addition, future developments planned for EUV interferometry at CXRO towards the measurement of actual EUV lithography optics will be shown.

Influence of Optical Parameters of Synchrotron Radiation Lithography Beamline on Pattern Replication

The influence of the angular divergence of X-rays incident on an X-ray mask and the exposure spectrum, which are the optical parameters determined by the geometric and band-pass properties of beamline optics and the synchrotron radiation (SR) spectrum, on resist pattern replication on various substrates was investigated. Using a compact storage ring as the SR source, we confirmed that there is no problem in 0.15-µm-feature pattern replication on Si substrate, regardless of the type of beamline optics. However, we found that an undercut or undeveloped portion inevitably occurs on a substrate which is covered with high atomic number material film, but this overexposure of resist can be reduced in a beamline with a broad band exposure spectrum.

Control of X-Ray Beam Fluctuation in Synchrotron Radiation Lithography Beamline

Using the focusing property of beamline optics, we have presented a new technique to directly measure the position and emission angle drifts of the synchrotron radiation (SR) source which may deteriorate the optical performance of a beamline consisting of focusing mirrors. A new methodology is also proposed to correct the SR source drifts, combining the above measuring technique, a SR beam position monitor (SRBPM) mounted on the beamline and the excitation of two steering magnets installed in a storage ring.

Effects of surface scatter on the optical performance of x-ray synchrotron beam-line mirrors

The increased availability of advanced synchrotron radiation sources is resulting in a resurgence of activity in the field of x-ray and extreme ultraviolet imaging systems. However, scattering effects caused by residual optical fabrication errors frequently dominate geometrical design errors in the degradation of image quality at these very short wavelengths. Traditional optical design and analysis techniques (geometrical ray tracing) are therefore inadequate for predicting the performance of high-resolution synchrotron beam-line optics. A surface-scattering theory must be implemented to model the image degradation effects of residual surface irregularities over the entire range of relevant spatial frequencies. This includes small-angle scattering effects caused by mid-spatial-frequency surface errors that fall between the traditional figure and finish specifications. Performance predictions are presented parametrically to provide insight into the optical fabrication tolerances necessary to meet the requireme nts of a specific application.

Preserving the high source brightness with x-ray beam line optics (invited)

A first-order challenge facing developers of x-ray beam line optics at synchrotron sources lies in producing optics that faithfully deliver the brightness of the source, especially in the presence of adverse power loads. Once overcome, continued use of beam line optics in experiments often reveals a second-order challenge, that of preservation of the source brightness over time, especially as conditions such as the storage ring current change. This requires maintaining stability, with beam line optics, of the peaks, widths, and centroid positions of the various parameters that contribute to the brightness, the wavelength, position, and angle distributions of the delivered photon beam. Some ideas on the use of x-ray monochromators, mirrors, apertures, and position-sensitive monitors to sense and stabilize the brightness parameter distributions, as well as methods to avoid or minimize transients in the first place, are presented. Examples based on experiences at the X25 wiggler beam line at the National Synchrotron Light Source are given.

A beamline for macromolecular crystallography at the Advanced Light Source

A beamline for macromolecular crystallography has been designed for the ALS. The source will be a 37-pole wiggler with a 2-T on-axis peak field. The wiggler will illuminate three beamlines, each accepting 3 mrad of horizontal aperture. The central beamline will primarily be used for multiple-wavelength anomalous dispersion measurements in the wavelength range from 4 to 0.9 Å. The beamline optics will comprise a double-crystal monochromator with a collimating premirror and a double-focusing mirror after the monochromator. The two side stations will be used for fixed-wavelength experiments within the wavelength range from 1.5 to 0.95 Å. The optics will consist of a conventional vertically focusing cylindrical mirror followed by an asymmetrically cut curved-crystal monochromator. This paper presents details of the optimization of the wiggler source for crystallography, gives a description of the beamline configuration, and discusses the reasons for the choices made.

High-brilliance Beamline at the European Synchrotron Radiation Facilitya)

The High-brilliance Beamline at the European Synchrotron Radiation Facility is under commissioning. First official user experiments are scheduled for September 1994. During the last months the beamline optics has been installed and extensively tested. Currently, the two end stations, (a) for macromolecular crystallography and (b) for time-resolved ultrasmall-angle x-ray scattering are under construction. This article presents the final optical setup of the beamline and describes the end stations. The actual performance of the undulator, the cryogenically cooled Si-(111) channel-cut monochromator, and the toroidal mirror are discussed. All results are in very good agreement with previously published theoretical calculations. Now, at the sample position a focused monochromatic beam is available between 0.15 nm (8 keV) and 0.077 nm wavelength (16 keV). At 0.1 nm wavelength the beam size is horizontally 0.38 mm and vertically 0.75 mm (full width at half-maximum) with a photon flux density of 2.5×107 photons/s/μm2 (±30%).

High energy scattering beamlines at European Synchrotron Radiation Facility

The scientific background and scope of research at the High Energy Scattering Beamlines of the European Synchrotron Radiation Facility are reviewed briefly. The beamline has two different insertion devices (IDs), a permanent magnet multipole wiggler and a superconducting wavelength shifter. The IDs can be used alternatingly, and both provide circularly polarized radiation off the orbit plane up to energies of several hundreds of keV. Measurements of the spectral brightness and the polarization components by energy dispersive powder diffraction and Compton scattering from iron in an alternating magnetic field are presented and compared with calculations based on source parameters. The beamline optics are based on use of horizontally reflecting bent Si crystals. These provide various focusing geometries, and the calculated flux of monochromatic radiation is given at energies between 30 and 175 keV. The maximum of 2×1012 photons/s is reached at 80 keV. The main experimental apparatus in the initial operation includes a high-resolution three-axis diffractometer, and a scanning-type Compton spectrometer.

The Australian National Beamline Facility at the Photon Factory (abstract)

The Australian National Beamline Facility has been installed at the Photon Factory, Tsukuba, Japan. The construction and operation of the facility has been funded by a consortium of Australian research organizations, universities, and government funding agencies, with the aim of providing Australian scientists with routine access to synchrotron radiation in the hard‐x‐ray region. The first experiments were performed at the ANBF in November 1992. The facility consists of a general purpose x‐ray‐beamline, including a simple two‐crystal monochromator, delivering either monochromatic x rays (range 5–20 keV) or white radiation to the experimental hutch. The main experimental instrument, a multiconfiguration diffractometer, has recently been installed at the beamline. This unique instrument combines vacuum operation and imaging plate detectors, and can be configured for high‐resolution powder diffraction (including a time resolved mode), protein crystallography, and triple‐axis experiments. In addition, the white or monochromatic beam can pass through the diffractometer to a secondary experimental table, where experiments such as EXAFS, Laue diffraction, topography, and microbeam measurements are performed. Details of the beamline, monochromator, and diffractometer optics and performance will be described, and an overview will be given of the experimental capabilities of the facility.

Optics of a high power wiggler beamline at the European Synchrotron Radiation Facility

The materials science beamline (BL2) at the European Synchrotron Radiation Facility (ESRF) can provide monochromatic or white radiation in the energy range from 7 to 100 keV. The source is a multipole wiggler with a maximum critical energy of 29 keV, producing a radiant power of up to 5 kW. The main optical elements are an adaptive mirror, a monochromator with a liquid nitrogen cooled first crystal followed by a sagittally bent second crystal, and a second mirror including a bender for vertical focusing. The general layout as well as the performance of the beamline optics during the commissioning phase of the ESRF are presented.