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

Description: 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.
Date: March 1, 2006
Creator: Naulleau, Patrick; Cain, Jason; Dean, Kim & Goldberg, Kenneth A.
Partner: UNT Libraries Government Documents Department

Antenna-coupled bolometer arrays using transition-edgesensors

Description: We describe the development of an antenna-coupled bolometer array for use in a Cosmic Microwave Background polarization experiment. Prototype single pixels using double-slot dipole antennas and integrated microstrip band defining filters have been built and tested. Preliminary results of optical testing and simulations are presented. A bolometer array design based on this pixel will also be shown and future plans for application of the technology will be discussed.
Date: June 8, 2004
Creator: Myers, Michael J.; Ade, Peter; Engargiola, Greg; Holzapfel,William; Lee,Adrian T.; O'Brient, Roger et al.
Partner: UNT Libraries Government Documents Department

The South Pole Telescope

Description: A new 10 meter diameter telescope is being constructed for deployment at the NSF South Pole research station. The telescope is designed for conducting large-area millimeter and sub-millimeter wave surveys of faint, low contrast emission, as required to map primary and secondary anisotropies in the cosmic microwave background. To achieve the required sensitivity and resolution, the telescope design employs an off-axis primary with a 10 m diameter clear aperture. The full aperture and the associated optics will have a combined surface accuracy of better than 20 microns rms to allow precision operation in the submillimeter atmospheric windows. The telescope will be surrounded with a large reflecting ground screen to reduce sensitivity to thermal emission from the ground and local interference. The optics of the telescope will support a square degree field of view at 2mm wavelength and will feed a new 1000-element micro-lithographed planar bolometric array with superconducting transition-edge sensors and frequency-multiplexed readouts. The first key project will be to conduct a survey over 4000 degrees for galaxy clusters using the Sunyaev-Zeldovich Effect. This survey should find many thousands of clusters with a mass selection criteria that is remarkably uniform with redshift. Armed with redshifts obtained from optical and infrared follow-up observations, it is expected that the survey will enable significant constraints to be placed on the equation of state of the dark energy.
Date: November 4, 2004
Creator: Ruhl, J.E.; Ade, P.A.R.; Carlstrom, J.E.; Cho, H.M.; Crawford,T.; Dobbs, M. et al.
Partner: UNT Libraries Government Documents Department

Quantum efficiency characterization of back-illuminated CCDs Part2: reflectivity measurements

Description: The usual quantum efficiency (QE) measurement heavily relies on a calibrated photodiode (PD) and the knowledge of the CCDs gain. Either can introduce significant systematic errors. But reflectivity can also be used to verify QE measurements. 1 - R > QE, where R is the reflectivity, and over a significant wavelength range, 1 - R = QE. An unconventional reflectometer has been developed to make this measurement. R is measured in two steps, using light from the lateral monochromator port via an optical fiber. The beam intensity is measured directly with aPD, then both the PD and CCD are moved so that the optical path length is unchanged and the light reflects once from the CCD; the PD current ratio gives R. Unlike traditional schemes this approach makes only one reflection from the CCD surface. Since the reflectivity of the LBNL CCDs might be as low as 2 percent this increases the signal to noise ratio dramatically. The goal is a 1 percent accuracy. We obtain good agreement between 1 - R and the direct QE results.
Date: January 19, 2006
Creator: Fabricius, Maximilian H.; Bebek, Chris J.; Groom, Donald E.; Karcher, Armin & Roe, Natalie A.
Partner: UNT Libraries Government Documents Department

EUV microexposures at the ALS using the 0.3-NA MET projectionoptics

Description: The recent development of high numerical aperture (NA) EUV optics such as the 0.3-NA Micro Exposure Tool (MET) optic has given rise to a new class of ultra-high resolution microexposure stations. Once such printing station has been developed and implemented at Lawrence Berkeley National Laboratory's Advanced Light Source. This flexible printing station utilizes a programmable coherence illuminator providing real-time pupil-fill control for advanced EUV resist and mask development. The Berkeley exposure system programmable illuminator enables several unique capabilities. Using dipole illumination out to {sigma}=1, the Berkeley tool supports equal-line-space printing down to 12 nm, well beyond the capabilities of similar tools. Using small-sigma illumination combined with the central obscuration of the MET optic enables the system to print feature sizes that are twice as small as those coded on the mask. In this configuration, the effective 10x-demagnification for equal lines and spaces reduces the mask fabrication burden for ultra-high-resolution printing. The illuminator facilitates coherence studies such as the impact of coherence on line-edge roughness (LER) and flare. Finally the illuminator enables novel print-based aberration monitoring techniques as described elsewhere in these proceedings. Here we describe the capabilities of the new MET printing station and present system characterization results. Moreover, we present the latest printing results obtained in experimental resists. Limited by the availability of high-resolution photoresists, equal line-space printing down to 25 nm has been demonstrated as well as isolated line printing down to 29 nm with an LER of approaching 3 nm.
Date: September 1, 2005
Creator: Naulleau, Patrick; Goldberg, Kenneth A.; Anderson, Erik; Cain,Jason P.; Denham, Paul; Hoef, Brian et al.
Partner: UNT Libraries Government Documents Department

Two-wave pattern shift aberration monitor for centrally obscuredoptical systems

Description: An aberration monitoring technique based on lateral shifts of two-wave interference patterns in centrally obscured optical systems is presented, and simulations are used to evaluate the performance of such a technique. The technique is being explored as a convenient means for monitoring the aberration level in the 0.3-NA Micro Exposure Tool (MET) optic over time. A binary mask was designed for observing phase differences across the MET optic on cut-lines at 0, 45, 90 and 135 degrees across the pupil. The mask consists of 5 line-and space patterns in a dark field that measure the side-to-side phase difference across the pupil at 7 equally spaced radial points extending from 35% to 95% of the pupil radius. For near on-axis illumination the blockage of the zero-order creates a two-wave, interferometric pattern at the wafer with half of the period expected under normal imaging conditions. The optical path difference between the two orders produces an image shift of one full period of the (frequency doubled) interference pattern per 360 degrees of side-to-side path difference. Shifts on the order of 5 to 20 nm are expected and are measured using a reference target of an array of 5 medium sized dots. Aerial image simulation is being utilized to predict the expected performance and to improve the initial design. The aberrations measured by interferometry are being used for this purpose. Also the quality of images at low partial coherence with the wavefront convergence present in the MET illumination is being studied. In addition to theory and simulation results, practical considerations in implementing this technique on actual lithography tools based upon MET-type optics are addressed, including pattern design, illumination characteristics, and data analysis.
Date: January 11, 2005
Creator: Cain, Jason P.; McIntyre, Gregory; Naulleau, Patrick; Pawloski,Adam; La Fontaine, Bruno; Wood, Obert et al.
Partner: UNT Libraries Government Documents Department

SNAP Satellite Focal Plane Development

Description: The proposed SuperNova/Acceleration Probe (SNAP) mission will have a two-meter class telescope delivering diffraction-limited images to an instrumented 0.7 square degree field in the visible and near-infrared wavelength regime. The requirements for the instrument suite and the present configuration of the focal plane concept are presented. A two year R&D phase, largely supported by the Department of Energy, is just beginning. We describe the development activities that are taking place to advance our preparedness for mission proposal in the areas of detectors and electronics.
Date: July 7, 2003
Creator: Bebek, C.; Akerlof, C.; Aldering, G.; Amanullah, R.; Astier, P.; Baltay, C. et al.
Partner: UNT Libraries Government Documents Department

Optimizing connected component labeling algorithms

Description: This paper presents two new strategies that can be used to greatly improve the speed of connected component labeling algorithms. To assign a label to a new object, most connected component labeling algorithms use a scanning step that examines some of its neighbors. The first strategy exploits the dependencies among them to reduce the number of neighbors examined. When considering 8-connected components in a 2D image, this can reduce the number of neighbors examined from four to one in many cases. The second strategy uses an array to store the equivalence information among the labels. This replaces the pointer based rooted trees used to store the same equivalence information. It reduces the memory required and also produces consecutive final labels. Using an array instead of the pointer based rooted trees speeds up the connected component labeling algorithms by a factor of 5 {approx} 100 in our tests on random binary images.
Date: January 16, 2005
Creator: Wu, Kesheng; Otoo, Ekow & Shoshani, Arie
Partner: UNT Libraries Government Documents Department

Flat-Field Calibration of CCD Detector for Long TraceProfilers

Description: The next generation of synchrotrons and free electron lasersrequires x-ray optical systems with extremely high-performance,generally, of diffraction limited quality. Fabrication and use of suchoptics requires highly accurate metrology. In the present paper, wediscuss a way to improve the performance of the Long Trace Profiler(LTP), a slope measuring instrument widely used at synchrotron facilitiesto characterize x-ray optics at high-spatial-wavelengths fromapproximately 2 mm to 1 m. One of the major sources of LTP systematicerror is the detector. For optimal functionality, the detector has topossess the smallest possible pixel size/spacing, a fast method ofshuttering, and minimal non-uniformity of pixel-to-pixel photoresponse.While the first two requirements are determined by choice of detector,the non-uniformity of photoresponse of typical detectors such as CCDcameras is around 2-3 percent. We describe a flat-field calibration setupspecially developed for calibration of CCD camera photo-response and darkcurrent with an accuracy of better than 0.5 percent. Such accuracy isadequate for use of a camera as a detector for an LTP with performance of~;0.1 microradian (rms). We also present the design details of thecalibration system and results of calibration of a DALSA CCD camera usedfor upgrading our LTP-II instrument at the ALS Optical MetrologyLaboratory.
Date: July 31, 2007
Creator: Kirschman, Jonathan L.; Domning, Edward E.; Franck, Keith D.; Irick, Steve C.; MacDowell, Alastair A.; McKinney, Wayne R. et al.
Partner: UNT Libraries Government Documents Department

Precision Tiltmeter as a Reference for Slope MeasuringInstruments

Description: The next generation of synchrotrons and free electron lasers require extremely high-performance x-ray optical systems for proper focusing. The necessary optics cannot be fabricated without the use of precise optical metrology instrumentation. In particular, the Long Trace Profiler (LTP) based on the pencil-beam interferometer is a valuable tool for low-spatial-frequency slope measurement with x-ray optics. The limitations of such a device are set by the amount of systematic errors and noise. A significant improvement of LTP performance was the addition of an optical reference channel, which allowed to partially account for systematic errors associated with wiggling and wobbling of the LTP carriage. However, the optical reference is affected by changing optical path length, non-homogeneous optics, and air turbulence. In the present work, we experimentally investigate the questions related to the use of a precision tiltmeter as a reference channel. Dependence of the tiltmeter performance on horizontal acceleration, temperature drift, motion regime, and kinematical scheme of the translation stage has been investigated. It is shown that at an appropriate experimental arrangement, the tiltmeter provides a slope reference for the LTP system with accuracy on the level of 0.1 {micro}rad (rms).
Date: August 1, 2007
Creator: Kirschman, Jonathan L.; Domning, Edward E.; Morrison, Gregory Y.; Smith, Brian V. & Yashchuk, Valeriy V.
Partner: UNT Libraries Government Documents Department

Proposal for a Universal Test Mirror for Characterization of SlopeMeasuring Instruments

Description: The development of third generation light sources like theAdvanced Light Source (ALS) or BESSY II brought to a focus the need forhigh performance synchrotron optics with unprecedented tolerances forslope error and micro roughness. Proposed beam lines at Free ElectronLasers (FEL) require optical elements up to a length of one meter,characterized by a residual slope error in the range of 0.1murad (rms),and rms values of 0.1 nm for micro roughness. These optical elements mustbe inspected by highly accurate measuring instruments, providing ameasurement uncertainty lower than the specified accuracy of the surfaceunder test. It is essential that metrology devices in use at synchrotronlaboratories be precisely characterized and calibrated to achieve thistarget. In this paper we discuss a proposal for a Universal Test Mirror(UTM) as a realization of a high performance calibration instrument. Theinstrument would provide an ideal calibration surface to replicate aredundant surface under test of redundant figure. The application of asophisticated calibration instrument will allow the elimination of themajority of the systematic error from the error budget of an individualmeasurement of a particular optical element. We present the limitationsof existing methods, initial UTM design considerations, possiblecalibration algorithms, and an estimation of the expectedaccuracy.
Date: July 31, 2007
Creator: Yashchuk, Valeriy V.; McKinney, Wayne R.; Warwick, Tony; Noll,Tino; Siewert, Frank; Zeschke, Thomas et al.
Partner: UNT Libraries Government Documents Department