In last year’s report, we discussed the design and requirements of the optical projection module (Projection Optics Box [POB]) for the 0.5-NA Micro-field Exposure Tool (MET5) and the resulting challenges. Over the course of this past year, we have completed and fully qualified the metrology of individual mirrors. All surface figure errors have been measured over seven orders of magnitude with spatial periods ranging from the full clear aperture down to 10 nm. The reproducibility of the full aperture tests measures 16 pm RMS for the M1 test and 17 pm for the M2 test with a target of 30 pm for both tests. Furthermore, we achieved excellent results on scatter and flare: For scatter, both mirrors perform about a factor of two below specification. For flare, the larger M2 mirror performs well within and the smaller M1 mirror about a factor of two below specification. In addition, we have developed processes for correcting surface figure errors for both mirrors and have successfully demonstrated high-reflectivity coatings on pathfinder mirrors. Further, we have achieved significant goals with respect to the design, assembly, metrology and alignment of the projection module. This paper reviews this progress and describes the next step in the ambitious MET5 POB development program.
In support of the Extreme Ultraviolet Lithography (EUVL) roadmap, a SEMATECH/CNSE joint program is underway to produce multiple EUVL (wavelength of 13.5 nm) R&D photolithography tools. The 0.5 NA projection optic magnification (5X), track length and mechanical interfaces match the currently installed 0.3 NA micro-field exposure tools (MET) projection optic [1] [2] [3]. Therefore, significant changes to the current tool platforms and other adjacent modules are not necessary. However, many of the existing systems do need upgrades to achieve the anticipated smaller exposure feature sizes [4]. To date we have made considerable progress in the production of the first of the two-mirror 0.5 NA projection optics for EUVL [5]. With a measured transmitted wave front error of less than 1 nm root mean square (RMS) over its 30 μm × 200 μm image field, lithography modeling shows that a predicted resolution of ≤12 nm and an ultimate resolution of 8 nm (with extreme dipole illumination) will be possible.
This paper will present an update from the 0.5 NA EUVL program. We will detail the more significant activities that
are being undertaken to upgrade the MET and discuss expected performance.
In support of the Extreme Ultraviolet Lithography (EUVL) roadmap, a SEMATECH/CNSE joint program is under way to develop 13.5 mn R and D photolithography tools with small fields (micro-field exposure tools [METs]) and numerical apertures (NAs) of 0.5. The transmitted wavefront error of the two-mirror optical projection module (projection optics box [FOB]) is specified to less than 1 mn root mean square (RMS) over its 30 μm x 200 μm image field. Not accounting for scatter and flare losses, its Strehl ratio computes to 82%. Previously reported lithography modeling on this system [1] predicted a resolution of 11 mn with a k-factor of 0.41 and a resolution of 8 mn with extreme dipole illumination. The FOB's magnification (5X), track length, and mechanical interfaces match the currently installed 0.3 NA FOBs [2] [3] [6], so that significant changes to the current tool platforms and other adjacent modules will not be necessary. The distance between the reticle stage and the secondary mirror had to be significantly increased to make space available for the upgraded 0.5 NA illumination modules [1].
The James Webb Space Telescope (JWST) is an on axis three mirror anastigmat telescope with a primary mirror, a
secondary mirror, and a tertiary mirror. The JWST mirrors are constructed from lightweight beryllium substrates and the
primary mirror consists of 18 hexagonal mirror segments each approximately 1.5 meters point to point. Ball Aerospace
and Technologies Corporation leads the mirror manufacturing team and the team utilizes facilities at six locations across
the United States. The fabrication process for each individual mirror assembly takes approximately six years due to
limitations dealing with the number of segments and manufacturing & test facilities. The primary mirror Engineering
Development Unit (EDU) recently completed the manufacturing process with the final cryogenic performance test of the
mirror segment assembly. The 18 flight primary mirrors segments, the secondary mirror, and the tertiary mirror are all
advanced in the mirror production process with many segments through the final polishing process, coating process, final
assembly, vibration testing, and final acceptance testing. Presented here is a status of the progress through the
manufacturing process for all of the flight mirrors.
During 2009, Tinsley finished most of the Configuration 1 pre-cryo test Computer Controlled Optical Surfacing (CCOS)
operations on the James Webb Space Telescope primary mirror segments and in mid-2009 we began the Configuration 2
post-cryo test CCOS operations. After completing the grinding and polishing operations, including final figuring to a
cryo-null target, we delivered the finished Engineering Development Unit (EDU) to Ball Aerospace Technology
Corporation on 4 December 2009. Achieving fabrication and metrology conditions to meet the specifications for this off-axis
~1.5 m hexagonal point-to-point segmented mirror required special methods. Achieving repeatable and accurate
interferometric alignment of the off-axis aspherical mirror surface and stable thermal gradient control of the beryllium
substructure during tests required rigorous component and system-level validation. Final optical wavefront
measurements over the various spatial frequency ranges have demonstrated that all of the requirements are met. This
success has validated our processes of fabrication and metrology and allows us to proceed with the production of the 18
flight mirror segments. The first finished flight mirror, the Tertiary Mirror, was shipped to BATC on 24 February, 2010.
Performance of that mirror is reported here also.
The EUV optical system of the Reticle Imaging Microscope (RIM) for EUV mask inspection consists of a pinched Xeplasma source, a pupil-relayed Koehler-type illumination system and an equal-radii Cassegrain-type microscope with a 10x magnification1.
The 3D surface topologies were characterized over spatial wavelengths ranging from the clear apertures down to a few nanometers by using a portfolio of instruments including contacting profilometry, phase-shifting interferometry at 633 nm at various magnifications and Atomic Force Microscopy. Measured 3D topography maps were Fourier analyzed and Power Spectral Densities (PSDs) are computed over spatial periods ranging from the critical aperture down to a few nm. Integrated RMS surface errors over typically reported spatial period ranges were computed. For a different optical system we improved our polishing process to reduce surface errors for spatial periods below 10 mm. PSDs and integrated RMS surface errors will be shown in comparison with typical RIM surfaces.
All surfaces of the RIM optical system were coated with high-reflectivity coatings to maximize optical throughput. A description of the coatings and their performance had been published recently by Michael Kriese et al.2 The transmitted wavefront error (TWF) of the imager module was measured in a double pass configuration using a Fizeau-type Interferometer at 633 nm wavelength and a convex retrosphere. The measured TWF will be shown over the entire Numerical Aperture (NA = 0.0625) of the microscope. The integrated RMS of the TWF measured 0.79 nm.
To perform actinic inspection of patterned EUV reticles with diffraction-limited resolution at 13.5 nm wavelength aspheric optical surfaces with surface figure errors and roughnesses well below 1 nm had to be developed.
The 3D surface topologies of prototype optical components were characterized over spatial periods ranging from the clear apertures down to 25 nanometers over 6 orders of magnitude by using a portfolio of instruments.
3D topography maps were Fourier analyzed and averaged Power Spectral Densities (PSDs) computed over the entire spatial frequency range. A good fit to the PSD was achieved with a linear function on a log-log scale. RMS values were computed over several spatial period ranges.
All optical surfaces were coated with high-reflectivity coatings to maximize optical throughput at 13.5 nm for the average angle-of-incidence of each optic. The spectral reflectivity of the HR coatings, consisting of Molybdenum-Silicon bi-layers (40 periods) were measured using synchrotron instruments at the NIST/DARPA EUV Reflectometry Facility and the Center for X-Ray Optics at Lawrence Berkeley National Laboratory. Total variations (PV) of peak-position within the clear-apertures ranged from 0.005 nm to 0.020 nm, with the one exception being a highly-curved convex surface yielding a PV variation of 0.040 nm. Peak reflectivity variation was typically 0.2% to 1% PV over the clear aperture, with some of the variation being instrument precision. One optic was coated with Ruthenium only, approximately 16nm thick, with less than ±0.1 nm variation in thickness. Detailed information on the spectral reflectivity for the coatings is discussed.
The next generation 193 nm (ArF) laser has been designed and developed for high-volume production lithography. The NanoLithTM 7000, offering 20 Watts average output power at 4 kHz repetition rates is designed to support the highest exposure tool scan speeds for maximum productivity and wafer throughput. Fundamental design changes made to the laser core technologies are described. These advancements in core technology support the delivery of highly line-narrowed light with <EQ 0.35 pm FWHM and <EQ 0.95 pm at 95% included energy integral, enabling high contrast imaging from exposure tools with lens NA exceeding 0.75. The system has been designed to support production lithography, meeting specifications for bandwidth, dose stability (+/- 0.3% in 20 ms window) and wavelength stability (+/- 0.05 pm average line center error in 20 ms window) across 2 - 4 kHz repetition rates. Improvements in optical materials and coatings have led to increased lifetime of optics modules. Optimization of the discharge electrode design has increased chamber lifetime. Early life-testing indicates that the NanoLithTM core technologies have the potential for 400% reduction of cost of consumables as compared to its predecessor, the ELX-5000A and has been discussed elsewhere.
This paper presents an evaluation on the 0.15 micrometers and 0.13 micrometers lithographic patterning alternatives for semiconductor devices. Baseline for the evaluation is a first generation ArF step and scan exposure system with 0.63 NA projection optics. The system layout is discussed and main performance data on imaging, overlay and throughput are presented. Binary masks, and various advanced 193 nm resist system are used to evalute process latitudes of dense lines, isolated lines and contact holes. The manufacturing economics, expressed in Cost Of Ownership, are evaluated for an ArF based production technology, and compared to critical layer KrF.
High throughput and/or high resolution imaging telescopes for x-ray energies up to 8 keV are part of several space based astronomic missions to study small and faint cosmic x-ray objects. High throughput telescopes are applied for spectroscopy missions, high resolution telescopes to detect and analyze small X-ray sources. Depending on the goal and the constraints of the mission some of the various parameters such as resolution, throughput, number of nested shells or weight etc. are optimized. The production technology has to match to the mission goals and constraints to obtain an optimum balance between scientific performance, production time and costs. The entire production process of XMM mirror shells at Carl Zeiss and Medialario (Italy) respectively will be presented in this paper. This technology will be compared with the ones of other x-ray telescopes such as EINSTEIN, EXOSAT, ROSAT, JET-X, AND AXAF; and EUV telescopes such as CDS and EUVE regarding potentials and limitations of the manufacturing processes and optical performances.
Each of the three mirror modules of the XMM Wolter-I-type telescope is composed of 58 nested mirror shells. The smallest gap between two adjacent mirror shells measures only 1.6 mm. The fixation and alignment concept has been qualified with the Optical Demonstration Model ODM, which consists of four CFRP mirrors. It has the same entrance diameter (700 mm) as the flight model. The 3D topology of the mirrors was determined for spatial wavelengths ranging from 3 micrometers to 550 mm by three measuring devices. The optical quality of the mirror shells as a function of x-ray energy was predicted by a code developed at Zeiss. During integration roundness and alignment of the mirrors were monitored by a full-aperture Hartmann-type test with visible light. The entire model and single mirrors have been x-ray tested at the MPE long beam facility at photon energies up to 8 KeV. The results of x-ray tests and performance predictions are compared and discussed.
The High Throughput X-Ray Spectroscopy Mission (XMM) is a `Cornerstone' Project in the ESA long-term Programme for Space Science. The satellite observatory uses three grazing incidence mirror modules coupled to reflection grating spectrometers and X-ray CCD cameras. In order to achieve a large effective area, each XMM mirror module shall consist of 58 Wolter I mirrors which are nested in a coaxial and cofocal configuration. This high packing density requires the production and integration of very thin mirror shells with diameters included between 300 and 700 mm. In 1991-93, a development program was run which aims to demonstrate the feasibility of such mirrors. Demonstration models which integrate mirrors having different sizes were manufactured using CFRP replication and Nickel electroforming technologies. These were X-ray tested. The proposed paper summarizes the activities and the test results obtained during this program.
The ESA High Throughput X-ray Spectroscopy Mission (XMM) is a telescope with three modules each consisting of 58 highly nested Wolter I mirrors with a focal length of 7.5 m. Envisaged resolution for an XMM module is 27 arcsec Half Energy Width at 8 keV x-ray energy. Due to the high packing density of the mirror shells within such a telescope, thin walled and light weight mirrors are required. In this paper the results of production, integration and performance tests of XMM CRFP/EPOXY mirror shells of all sizes (diameters from 300 mm to 700 mm; length equals 600 mm; wall thickness from 0.7 mm to 1.3 mm) for the XMM telescope will be reported.
The study predicts, on the basis of surface topology measurements, the optical performance of thin-walled Wolter type 1 mirror shells over the specified energy range of the XMM telescope (0.3-8 keV). To analyze the effect of deformations which can be treated by geometrical optics, a Monte Carlo code was developed which uses a 3D model of the telescope to trace individual rays through the telescope. The computed point spread functions are found to be in excellent agreement with the ones measured in a full-aperture test at 1.5 keV X-ray energy. At 8 keV, a loss in optical performance was observed. A comparison of the surface data with mirrors that performed efficiently at 8 keV showed deformations with spatial wavelengths below 1 mm to be responsible for the degradation at 8 keV X-ray energy. It is concluded that in the transition region between Rayleigh limit and smooth surface limit, approximate optical predictions can be achieved by applying geometrical optics.
The Joint European X-Ray Telescope, JET-X, is one of the core instruments of the scientific payload of the Russian SPECTRUM-X astrophysics mission due for launch in 1995. JET-X is designed to study the emission from X-ray sources in the band from 0.3 to 10 keV, particularly to meet primary scientific goals in cosmology and extragalactic astronomy. JET-X consists of two identical, coaligned X-ray imaging telescopes, each with a spatial resolution of 30 arcsecond (Half Energy Width, HEW) or better. Each telescope is composed of a nested array of 12 mirrors with an aperture of 0.3 m and a focal length of 3.5 m. The mirror shells have Wolter I geometry and are replicated by an electroforming process for which Carl Zeiss manufactured the 12 monolithic Nickel coated aluminum mandrels. In order to determine the mandrel limited HEW, several measurement and analysis steps including raytracing calculations are performed. The major contributions to the error budget, axial slopes and roundness errors, as well as the position of the focus are investigated. The results are reported and discussed.
Attention is given to the ESA High Throughput X-ray Spectroscopy Mission (XMM), a telescope with three modules each consisting of 58 highly nested Wolter I mirrors with a focal length of 7.5 m. The envisaged resolution for an XMM module is 27 arcsec half energy width (HEW) at 8 keV X-ray energy. Results are presented of production and performance tests of the medium-size XMM CFRP/EPOXY mirror shell, including: the production of CFRP carriers as the mirror shell substrate with a global ovality PTV(R) of less than 50 microns and HEW contribution due to roundness of less than 10 arcsec; the replication of Wolter I shaped reflecting gold surface on the CFRP substrate; the measurement of optical performance (HEW is less than 17 arcsec at 1.5 keV X-ray energy); and an investigation of long-term stability for the 10-yr mission time. It is shown that the CFRP/EPOXY mirror shell replication technology can meet the XMM mission requirements.
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