ALSNews is a biweekly electronic newsletter to keep users and other interested parties informed about developments at the Advanced Light Source, a national user facility located at Lawrence Berkeley National Laboratory, University of California. To be placed on the mailing list, send your name and complete internet address to ALSNews@lbl.gov. We welcome suggestions for topics and content.

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ALSNews           Vol. 97           March 4, 1998

Table of Contents


    1. USERS' TOWN MEETING MARCH 6
    2. EUV LITHOGRAPHY PROGRAM MAKING ITS MARK
    3. WHO'S IN TOWN: A SAMPLING OF ALS USERS
    4. OPERATIONS UPDATE

1. USERS' TOWN MEETING MARCH 6
(contact: w_meyer-ilse@lbl.gov, g_krebs@lbl.gov)

The ALS Users' Executive Committee (UEC) will meet on March 6. That afternoon, from 3:00 to 4:30, there will be a Town Meeting for all interested users in the first-floor conference room in Building 2. The agenda so far is as follows:

   - Introduction (C. Shank, P. Oddone)
   - ALS Workshop (B. Kincaid, N. Smith)
   - Report from UEC Meeting (W. Meyer-Ilse)
   - ALS Parameters/Third Harmonic Cavity (A. Jackson, D. Robin, J. Byrd)
   - User Discussions (see below)

2. EUV LITHOGRAPHY PROGRAM MAKING ITS MARK
(contact: dtattwood@lbl.gov)

Making the microchip of the future will require production methods of nearly immeasurable precision. Features that are now a mere 250 nm across will be miniaturized almost threefold in the next ten years. Today, some key members of the semiconductor industry are betting that extreme ultraviolet (EUV) lithography will make it possible. The very-high-accuracy measurement techniques that are likely to make this manufacturing technology a reality in the early twenty-first century are being developed now at the Center for X-Ray Optics (CXRO) EUV lithography beamlines. Supported by the largest cooperative research and development agreement (CRADA) in U.S. Department of Energy history, the program is aiming toward implementation of a production EUV lithography camera between 2004 and 2007.

Current chip manufacturing technology uses light with wavelengths down to 248 nm, which is projected through a patterned mask to etch the pattern onto a silicon wafer. These deep ultraviolet techniques are expected to reach a limit at feature sizes around 130 nm because of increasing absorption by refractive optics and shrinking depth of focus with shorter wavelengths. Skipping down to the EUV region of the spectrum (to wavelengths near 13 nm) allows higher spatial resolution and improved depth of focus, but it also requires the development of advanced reflective optics to focus the light as perfectly as possible. Since any test of a mirror's perfection must be at least as perfect as the mirror itself, measuring the quality of such optics and their coatings presents significant challenges. It is in this area of minute measurement that the CXRO beamlines are making their mark.

Two EUV lithography beamlines are now in operation. The Calibration and Standards Beamline, 6.3.2, is used for measurements of reflectivity and scattering from the multilayer mirrors used to focus EUV light. The small, stable beam from an ALS bend magnet has made it possible to engineer a beamline capable of measuring variations in the spacing of a multilayer coating to better than one part in one thousand. Researchers have also recently obtained unique measurements of nonspecular scattering from multilayer mirrors. (See ALSNews Vol. 96.) While scientists at Beamline 6.3.2 analyze one mirror at a time, those working at Beamline 12.0.1 study the optical quality of systems of mirrors. They are developing a phase-shifting, point-diffraction interferometer to test the optical quality of the entire lithography camera. Using the partially coherent light from an ALS undulator makes extremely accurate measurements possible with exposure times of a few seconds. The endstation recently surpassed a significant programmatic milestone: measuring a spherical wavefront to an accuracy of 1/100 of the incident wavelength or better. The accuracy achieved was 1/250 of a 13.4-nm wavelength--a wavefront error equal to the radius of a hydrogen atom. (See ALSNews Vol. 94.)

Two new beamlines now under construction are modeled after Beamline 6.3.2. The first of these, Beamline 6.3.1, will meet increasing demand for calibration and standards beam time and accommodate higher photon energies (up to about 2 keV). The endstation will be the same as that on Beamline 6.3.2, and half the beam time will be available to independent investigators. Also under construction is Beamline 11.3.2, which is essentially a replica of beamline 6.3.2 but with an endstation for inspecting mask defects. Both new beamlines are expected to be completed by this fall.

The EUV lithography work being conducted at the ALS is part of a three-year, $250 million CRADA between the "Virtual National Laboratory," which comprises Lawrence Livermore National Laboratory, Sandia National Laboratories, and Berkeley Lab, and the EUV Limited Liability Corporation, a consortium of semiconductor industry leaders including Intel, Advanced Micro Devices, and Motorola.

3. WHO'S IN TOWN: A SAMPLING OF ALS USERS

To highlight the richness of our user community and help introduce recent arrivals, we offer this listing of some of the experimenters who will be collecting data during the next two weeks at the ALS.

Beamline 7.0.1: David Shuh (Berkeley Lab) will do soft x-ray emission spectroscopy for the determination of metal ion speciation in environmental materials. Roy Willis (Pennsylvania State U.) will study magnetic alloys using optical dichroism and spin-polarized electron spectroscopy. Rainer Fink (U. Wuerzburg, Germany) will study orientational inhomogeneities in thin films of DCNQI- and TCNQ-based charge transfer salts. Joseph Nordgren (Uppsala U., Sweden) will conduct several short studies in the spectroscopy of molecules and materials.

Beamline 8.0.1: Eberhard Umbach (U. Wuerzburg) will make a soft x-ray fluorescence and photoemission investigation of the buried CdS/Cu(In,Ga)Se2 interface. Yasuji Muramatsu (Integrated Information and Energy Systems Laboratories, Nippon Telegraph and Telephone Corporation) will perform soft x-ray emission and absorption spectroscopy of hybrid nanoclusters for sensing/electronic devices.

Beamline 9.3.2: Hyuk Choi, Ernesto Escorcia, Roland Kawakami, Martin Bowen, and Zi Q. Qiu (U. California, Berkeley) will study the effect of lattice symmetry-breaking on the magnetic properties of iron and palladium films.

Beamline 10.3.1: Scott McHugo (Berkeley Lab) will investigate the location of trace elements in polycrystalline solar cells. Nancy Buening (U. California-Davis) will study the spatial distribution of elements in fossilized sea shells. Geraldine Lamble (Berkeley Lab) will conduct x-ray fluorescence microprobe studies of the distribution of metal ions accumulated in symbiotic fungi inhabiting organic surface soils in temperate forest ecosystems.

Beamline 12.0.1.1: Giorgio Margaritondo (Laboratoire de Physique Des Materiaux Electroniques, Switzerland) will investigate interfaces in gallium selenide (GaSe) using the MAXIMUM spectromicroscope.

4. OPERATIONS UPDATE
(contact: rmmiller@lbl.gov)

Beam reliability for the last two weeks (February 17 - March 1) was 89.2% overall and 88.6% for user shifts. A Lab- and campus-wide power dip caused an outage on February 20 when a storage ring rf crowbar trigger chassis (which disconnects the klystron from its power supply when there is a fault) would not reset. An ion pump trip elevated pressure in the booster ring and prevented storage-ring fills for 5 hours on Sunday evening, February 22 while the booster ring was pumped back down.

An outage not reflected in these percentages began late on March 2, when beam would not stack. Technicians located and removed a scintillator paddle (used to show beam position just downstream of injection to the storage ring) that had come off its holder, but beam still would not stack. Accelerator physicists then steered the beam until they found an orbit with a large local bump in Sector 11 that allowed beam stacking, but the orbit was unsatisfactory for operations. On Tuesday afternoon, technicians vented Sectors 10, 11, and 12 and located a horizontal scraper blade that had come off its actuator. The blade was removed, the storage ring sealed, and operations resumed by 11 p.m. Tuesday. Beam lifetime is approximately 2 hours at 400 mA and improving.

Long-term and weekly operations schedules are available on the Web (http://www-als.lbl.gov/als/als_ops/ops_home.html). Weekly operations scheduling meetings are held on Fridays at 3:30 p.m. in the Building 6 conference room. The Accelerator Status Hotline at (510) 486-6766 (ext. 6766 from Lab phones) features a recorded message giving up-to-date information on the operational status of the accelerator.