**** **** **** * * * * * * **** **** **** * * * * * * **** **** * * **** HEADLINES - a digital monthly publication
Contents of This Issue:
1. Science Highlight - Looking at Trace Impurities on Silicon Wafers Using Synchrotron
(contact: Katharina Lüning)
Today's very sophisticated integrated circuits contain more than 100 million transistors and their fabrication involves complex processing steps like silicon dioxide growth, plasma etching, metal deposition, high-energy dopant implantation, or wet chemical cleaning. All these processes are potential sources of surface contamination and even very low levels of metal impurities can cause serious degradation of silicon integrated circuits by diminishing carrier lifetime, reducing the dielectric breakdown of gate oxides and causing leakage currents in p-n junctions.
The only nondestructive analytical technique available for detecting trace impurities on semiconductor surfaces with high sensitivity is x-ray fluorescence spectroscopy based on total external reflection of the incident x-ray beam (TXRF). However, the detection limit required for extremely low contamination levels (1 fg) is beyond the capability of conventional, rotating anode-based TXRF instruments. This has driven the development of synchrotron radiation-based TXRF facilities that have significantly better sensitivities than what is possible with the conventional systems. Such a facility is now operating routinely on BL6-2 at SSRL.
In addition, researchers at SSRL have recently demonstrated that the chemical state of surface impurities can be investigated at trace levels by combining TXRF with x-ray absorption near edge spectroscopy (XANES). How this contributes to developing more efficient wafer cleaning processes can be found in the following science highlight. This work was featured as the cover story of the December 1, 2002 issue of Analytical Chemistry.
More information regarding this research can be found on the SSRL Home Page (click on the Dec 2002 Science Highlight link). Please see the SSRL Science Highlights page for an archive of the highlights.
2. Holiday Greetings from the SSRL Director
Dear Users, Colleagues and Friends of SSRL - as the end of 2002 rapidly approaches, I would like to reflect back on the past year and thank you all for your help and support.
We continue to be very pleased that SSRL and its dedicated staff are able to serve you, the users, to enable cutting edge scientific discoveries in many areas. With your continued input, we have been very successful in providing science highlight examples each month in the SSRL on-line newsletter. The archive of these highlights is an impressive record of the scientific achievements you and your collaborators have made using SSRL.
Looking toward the coming year and longer-term future, we continue to make excellent progress on the SPEAR3 upgrade (see the article later in this newsletter) and we are now making final preparations for the shutdown of SPEAR2 at the end of March, 2003. We are planning a small event to mark the end of a remarkable era of a machine that transformed the way of doing science in two fields - high energy physics and synchrotron science. Following commissioning late in 2003, SPEAR3 will deliver to you beams with much higher brightness and intensity to provide the opportunity for exciting new science. In parallel, we continue to make improvements on existing beam lines, e.g. with deployment of additional liquid nitrogen cooled monochromators and new mirror systems.
Working with our colleagues at SLAC and several other institutions, we are developing capabilities to produce for ultra-short pulse, high brightness x-ray beams. First, in Spring, 2003, we will begin the subpicosecond photon experiment (SPPS) - utilizing a very compressed electron beam from the SLAC linac to produce bursts of 80-fsec 1-Å x-rays from an undulator that has recently been installed at the end of the SLAC accelerator housing. This experiment will allow a collaboration of institutions to gain direct experience with characterizing the beam, working out synchronization techniques and doing experiments on more strongly scattering materials. This experience will be very valuable for our X-ray FEL project (LCLS). This year, LCLS received DOE approval for "critical decision 1" which means we can begin detailed engineering and design. A new Science Advisory Committee for LCLS is now working with us in close cooperation with DOE-BES to begin to define how to move forward on planning the experimental science program. Our schedule calls for first laser light in 2008 with project completion and full operation in 2008.
A number of other things have happened this year, and one important highlight includes groundbreaking on the new SLAC Guest House, which will provide affordable, on-site housing for you, our users, starting mid- 2003. It has been a busy year in many other ways - hosting visits by DOE Secretary Abraham, several staff from our local congressional delegations and many others. Together with our colleagues at SLAC, we celebrated the 40th anniversary of the laboratory. We have continued to work closely with our sister DOE light sources and their management and user organizations to coordinate our efforts to find the best means to serve the synchrotron needs of the user community.
I would like to express a most sincere "thank you" to those who serve on our advisory committees - the Proposal Review Panel, the SLAC Scientific Policy Committee, the SSRL Users' Organization Executive Committee, the SMB Advisory Committee and the LCLS SAC and TAC for their tireless work and advice. Your guidance is extremely important to help us plan and move forward in the wisest and most effective ways. We continue to be very grateful to our funding agencies - the Department of Energy Office of Basic Energy Sciences for providing the core operations funding and support for materials research and the DOE Office of Biological and Environmental Research and the National Institutes of Health NIGMS and NCRR Programs for support of the structural biology program. Without their effective support, we would not be able to push the technological forefront and serve such a large and growing user community.
Lastly, I would like to urge all of you to continue to let us know your opinions and ideas - it helps us serve you better, improve our operations and plan most effectively for the future. In closing, on behalf of SSRL and its staff, let me extend our very best wishes to all of you for the holiday season and for 2003!
- Keith Hodgson, SSRL Director
3. SPEAR3 Lehman Review
(contact: Tom Elioff)
A DOE (Lehman) Review of the SPEAR3 program was held December 4-5. While overall progress since the last review (July 16-18, 2002) was summarized, the main objective was to "review the Installation Plan in total, including associated cost and schedule and assess the Project's disposition of the July review committee recommendations on the Installation Plan." In addition, the ES&H activities planned for the next year were presented. A summary of the committee's draft report for the December review is provided below.
The project has made good progress since the last review
July 16-18, 2002. The magnet and power supplies systems
have completed most technical equipment fabrication. The
vacuum system has resolved issues with chamber production
and the completion schedule will meet installation plan
requirements. The RF cavities are in production after
electroforming issues were resolved with the vendor.
Delivery milestone for the four cavities is sufficent for
final assembly and checkout. All conventional construction
activities have been completed during the past three annual
downtimes. Accelerator Physics and Controls systems have
developed resource loaded schedules to complete critical
activities to support SPEAR3 startup. The installation plan
continues to be optimized. The current version of the plan
includes additional details with updated activities, resources
and costs. ES&H plans are being prepared for the Accelerator
Readiness Review and installation activities. The Final
Safety Analysis Document will be ready for review early next
The project conducted a contingency analysis as recommended by the last DOE review to identify current contingency budget and to forecast potential issues that could draw down these funds. This evaluation was important to allow management to properly manage the conclusion of project activities.
General Comments included the observation that the SPEAR3 team has made excellent progress in using the scheduled maintenance periods to perform as much preinstallation activities as possible. SPEAR3 remains on track for its installation phase to begin in early April, 2003. Following commissioning in late fall, first users are expected back in early, 2004.
4. Biannual Scientific Policy Committee Meeting
The Scientific Policy Committee (SPC), the highest level advisory board for all of the science programs at SLAC, and which reports to Stanford President John Hennessy, met on December 6-7, 2002. Drs. Douglas Rees (Caltech), Marvin Cassman (UCSF) and Denis Roux (Synchrotron Soleil) have rotated onto the committee, joining continuing member Jens Als-Nielsen (Niels-Bohr Institutet) in representing the synchrotron radiation area. Many thanks to representatives Anthony Kossiakoff (University of Chicago) and Sol Gruner (Cornell) who have just completed their terms of service.
Several synchrotron-related presentations were made at the meeting, including talks on SPEAR3, LCLS, SPPS, beam line development and science highlights. The committee was very positive about the work being done at SSRL and the progress toward and plans for the future (SPEAR3, SPPS and LCLS). One suggestion was that the SSRL and SLAC users' organizations should consider working more closely together where possible. For the most part SSRLUO and SLUO represent user communities with very different needs and concerns, but there are areas of common interest such as visibility of DOE science, user accommodations and the LCLS. The SSRLUO Executive Committee will seek means to better coordinate with the SLUO (the sister organization for the other programs at SLAC).
5. SSRLUO-EC Meeting
(contact: Uwe Bergmann, Chair, SSRLUO-EC)
The SSRL Users' Organization Executive Committee met with members of the SPEAR3 Task Force on December 9 to discuss what users can expect when operations resume in January 2004. Tom Rabedeau shared slides which outlined plans and priorities for beam line development both now and post SPEAR3. The top priority remains to have all beam line front ends 500 mA capable when SPEAR3 turns on. Insertion device beam lines are next and bending magnet beam lines are the final priority -pending availability of resources. Users have expressed the desire to see as many beam lines operating again in January 2004 as possible. Based on prior experience with commissioning accelerator systems, SSRL hopes to develop ramp-up plans that make it possible to operate most of the beam lines during the first several months of the 2004 run while work is ongoing to reach the 500 mA milestone. To meet this objective, several beam line engineers are actively working to develop ways for the bending magnet beam lines to accept higher than 100 mA current so that they may be utilized early in the 2004 run.
(See SPEAR3 Update Page)
6. Latest SRI 2003 Information Available Online
(contacts: Jo Stöhr and Howard Padmore)
New information related to the 2003 International Conference on Synchrotron Radiation Instrumentation (SRI 2003) is now posted at the official conference web site. SRI 2003 will be hosted jointly by SSRL and ALS and chaired by Jo Stöhr (SSRL) and Howard Padmore (ALS). The conference will be held August 25-29, 2003, at the Yerba Buena Center for the Arts in downtown San Francisco. The updated SRI 2003 Web site includes information about the venue, accommodations, abstract submission and registration. A second announcement will be sent out in the next few days to the 10,000 plus people currently on the mailing list. Organizers plan to handle most of the meeting correspondence (announcements, abstract submission/review and registration) via electronic means. The conference proceedings will be published through the American Institute of Physics.
7. SLAC Guest House Accepting Reservations!
(contact: Cathy Knotts)
As those of you who have visited the SLAC site recently will have noted, the SLAC Guest House construction is well underway with a projected opening of July 2003. Stanford University Student Housing Services will manage the Guest House for SLAC and reservations are now being accepted for stays beginning July 1, 2003. Reservations can be made by telephone (650-926-2800) or via the SLAC Guest House web page.
We hope you will take advantage of this long-awaited on-site lodging option for your future visits to SSRL, and suggest that you plan ahead by choosing the SLAC Guest House as a low-cost lodging alternative for the August SRI2003 meeting (San Francisco is a relatively easy drive up I-280) or for the 30th Annual SSRL Users' Meeting which will be held here on October 8-10, 2003. Please visit the web site listed above for additional SLAC Guest House information, including rates.
8. Upcoming Events at SSRL and Elsewhere
9. User Research Administration Announcements
(contacts: Cathy Knotts and Lisa Dunn)
The SLAC Café will be closed December 23-January 1, with only limited food service available on January 2-3 (no hot entrees). Regular cafeteria service will resume Monday, January 6. (see: SLAC Café page)
The Stanford University Marguerite shuttle service and SLAC CalTrain shuttles will not operate the week of December 23 through December 27. Normal service will resume on December 30.
SSRL Headlines is published electronically monthly to inform SSRL users, sponsors and other interested people about happenings at SSRL. SSRL is a national synchrotron user facility operated by Stanford University for the U.S. Department of Energy Office of Basic Energy Sciences. Additional support for the structural biology program is provided by the DOE Office of Biological and Environmental Research, the NIH National Center for Research Resources and the NIH Institute for General Medical S ciences. Additional information about SSRL and its operation and schedules is available from the SSRL WWW site.
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