PHOTOMASK BACUS The international technical group of SPIE dedicated to the advancement of photomask technology.

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1 PHOTOMASK BACUS The international technical group of SPIE dedicated to the advancement of photomask technology. JULY 2007 VOLUME 23, ISSUE 7 Novel Technique for Critical Dimension Measurements of Phase-shift Masks Using Broadband Transmittance Spectra in Conjunction with RCWA Alexander Gray, University of California at Davis, CA John C. Lam and Stanley Chen, n&k Technology, Inc., Santa Clara, CA ABSTRACT For the first time Rigorous Coupled Wave Analysis (RCWA) has been applied to the analysis of the transmittance spectra for the determination of critical dimension (CD) of phase-shift photomasks. The use of transmittance spectra proved to be instrumental in improving the sensitivity of the measurement to minor (sub-nanometer) changes in the width of the trench. We present a novel unique metrology solution based on the simultaneous measurement of broadband reflectance and transmittance, covering a wavelength range from 190 to 1000 nm, in one nanometer intervals. The analyses of both types of spectra are performed simultaneously, using Forouhi-Bloomer dispersion equations, in conjunctions with RCWA. The method provides accurate and repeatable results for critical dimensions, thickness, and optical properties (n and k spectra from nm) for all materials present in the structure. In the current study, the method described above was used to examine grating structures on ACI (After-Clean Inspection) phase-shift mask. The use of transmittance spectrum proved to be essential for the accurate measurement of the CD, since the transmittance spectrum is more sensitive to the change in line width, compared to the reflectance spectrum. The results were compared with the measurements taken on the same sample using conventional CD-SEM. The CD linearity study demonstrated excellent correlation with CD-SEM. The advantages of the optical reflectance and transmittance method are high throughput, non-destructive nature of the measurements and capability to measure a wider variety of structures pertinent to the photomask manufacturing process. TAKE A LOOK INSIDE: INDUSTRY BRIEFS For new developments in technology see page 8 CALENDAR For a list of meetings see page 9 Continues on page 3. R s R p Figure 1. Typical variation in the polarized reflectance spectra (R s and R p ) due to 40 nm variation in line width of a 600nm - pitch grating.

2 Page 2 Volume 23, Issue 7 N E W S Editorial N E W S Things that make me go Hmmm Warren Montgomery, CNSE When I began my career in this industry It occurred to me, a short time ago, that I am now considered an old timer in our industry. My career started back in the late 70s, at IBM, where I worked on photoresist development using contact printing. Back then, we were happy to have the ability to print 5-10µm features with a bias of 1µm. In those days, batch processing was in vogue, and a single operator would run 3-4 tools simultaneously. Looking back fondly, those were the good old days! BACUS News is published monthly by SPIE for BACUS, the international technical group of SPIE dedicated to the advancement of photomask technology. Circulation Managing Editor/Graphics Linda DeLano Advertising Sue Siegfried BACUS Technical Group Manager Pat Wight Photoresist used to be extendable Photoresists were relatively simple in design; the composition was 2-1-4, or some mixture of diazoquinone sensitizer, a novolak resin and a safe casting solvent with a boiling point of about 140 centigrade. Diazoquinone (DNQ) photoresist formulations were used to meet lithographic ground rule requirements for about 15 years (1979 to about 1994.) As resolution requirements tightened, exposure tool companies changed the exposure wavelength to 248nm, which signaled the end of DNQ resist use for critical layers. Novolak resin simply absorbs too strongly at 248nm. In order to satisfy the needs of Deep UV (DUV), IBM developed and implemented chemically amplified photoresists (CAR) which were used for critical layers, from 1994 to As fate would have it, moving to CAR was facilitated by the move to single wafer processing schemes and the introduction of the photocluster (The semiconductor gods were kind to the industry) BACUS Steering Committee Maskmakers were on holiday 2007 Annual Photomask Chairs Robert (Bob) J. Naber, Cadence Design Systems, Inc. Hiroichi Kawahira, Sony Atsugi Technology Ctr. (Japan) And how were maskmakers keeping pace with developing technologies? (Can you say maskmakers holiday? ) Since the critical dimension on the mask is 4 times (4X) the dimension on the wafer, the mask shop was able to use DNQ chemistry a few years longer than the wafer side of the industry. The transition from DNQ chemistry to DUV from a laser-writer perspective started in 1999 (focused on masks for critical layers, of course.) With that transition, CAR resist-processing issues arose. These issues stacked squarely up against the maskmakers, who, up until this point, had been able to rely on precoated mask blanks for years. The problems manifested themselves as environmentally induced contamination, CD variability while writing, standing waves (due to the use of a BARC targeted for non-car resist and high reflectance off the substrate), and photoresist supply challenges due to low volume consumption by the mask industry. Luckily, maskmakers were able to use some of the techniques developed by the wafer side of the industry, such as carbon filtering and chemical monitoring of the factory environment. What s next? Now I m finding myself asking what the next lithographic technology will be. Will it be imprint lithography, EUV lithography, or is 193nm immersion going to mark the end of the lithography superhighway? Will e-beam lithography finally prove to be an option in spite of the throughput issues? Imprint lithography seems to be making real progress, but still faces major technological challenges. EUV lacks a mature infrastructure; the industry is just now learning to make masks, sources and photoresists that are useful in EUV technology. Double exposure, using 193nm, appears to be the most promising option, but it won t come cheap. Double patterning will put tremendous pressure on the scanner equipment suppliers in the area of overlay. Companies like Applied Materials, Tokyo Electron and others will need to continue to develop cutting-edge technologies like the new AMAT etch processes that have achieved extremely small lithographic features using hardmask processing techniques. There is no shortage of reviews of the materials requirements and development challenges which will be faced if 193nm immersion lithography is to be extended beyond the current projection of ~1.35NA (see last year s SPIE proceedings). In order to continue the drive toward higher NAs, high index immersion fluid and high index optical elements for 193nm scanners must be created. High NA lithography will force the development of new photoresist materials, BARC and top antireflective coatings. Without question, any discussion of advances in optical lithography must include Optical Proximity Correction (OPC.) Just look at the current wave of mergers and acquisitions, specifically ASML s recent acquisition of Brion, which demonstrates the importance of modeling and verification technologies. I d estimate that the semiconductor industry will utilize dry 193nm in the near term, then move to 193nm immersion lithography at ~1.35NA, then perhaps to double exposure lithography at ~1.35NA, and finally to EUV Lithography. This approach will allow the time required to solve the technical challenges facing EUV lithography. Lithography has always been a challenge for the semiconductor industry, but we have always found a technical solution to the issues at hand. My guess is the industry has a couple of technological breakthroughs still left in it; time will tell. President Patrick M. Martin, Photronics, Inc. Vice President Brian J. Grenon, Grenon Consulting Secretary John Whittey, Vistec Semiconductor Systems, Inc. Quarterly Meeting Chair Robert (Bob) Naber, Cadence Design Systems, Inc. International Chair Wilhelm Maurer, Infineon Technologies AG (Germany) Education Chair Wolfgang Staud, Invarium, Inc. Sponsorships Susan Siegfried, SPIE Sponsorship Consultant Members at Large Ki-Ho Baik, Intel Corp. Artur Balasinski, Cypress Semiconductor Corp. Uwe Behringer, UBC Microelectronics (Germany) Ute Buttgereit, Carl Zeiss SMS GmbH (Germany) Chris Constantine, Oerlikon USA Inc. Benjamin G. Eynon, Jr., Sematech Gregory K. Hearn, SCIOPT Enterprises Kurt Kimmel, IBM Microelectronics Div. Paul Leuhrmann, ASML Mark Mason, Texas Instrument Inc. Warren Montgomery, Albany Nanotech John A. Nykaza, Toppan Photomask, Inc. J. Tracy Weed, Synopsys, Inc. Larry S. Zurbrick, KLA-Tencor Corp Society of Photo-Optical Instrumentation Engineers. All rights reserved. P.O. Box 10, Bellingham, WA USA Tel: Fax: SPIE.org customerservice@spie.org

3 Volume 23, Issue 7 Page 3 Continued from cover. Figure 2. Typical variation in the polarized transmittance spectra (T s and T p ) due to 40 nm variation in line width of a 600nm - pitch grating. Figure 3. Typical fit between four measured spectra (R s -exp, R p -exp, T s -exp, T p -exp) and their calculated counterparts (R s -cal, R p -cal, T s -cal, T p -cal). I. Introduction Measurement of the critical dimensions (CD) on phase-shift photomasks has become one of the central problems in modern-day metrology. Vast amounts of resources are being channeled towards the efforts to improve the accuracy, sensitivity and reliability of the existing techniques and development of the new ones. Conventional techniques, such as CD-SEM, AFM and Interferometry are being replaced by faster, non-destructive, non-contact optical techniques. A number of techniques based on optical reflectometry have proven to be successful in CD measurements, however, problems with measurement sensitivity push the metrology companies to explore new hardware solutions and develop new computational analysis algorithms. In this article we present a new metrology method, based on broadband measurements of reflectance and transmittance spectra. For the first time Rigorous Coupled Wave Analysis (RCWA) is applied to the analysis of the transmittance spectra for the determination of critical dimensions of phase-shift photomasks. Section II (Sensitivity and Resolution) underlines the necessity of the new technique. In Section III (RCWA Method for Transmittance Spectra) the new calculation algorithm is described. Sections IV and V outline the methodology and the measurement results. II. Sensitivity and resolution As the product specifications become tighter, the question of measurement resolution and sensitivity becomes more and more critical. The conventional reflectance-based scatterometry is often limited by the fact that a small variation in line width does not correspond to a measurable change in the spectral reflectance. As a result of this, it is sometimes impossible to resolve the difference between acceptable and defective products. Tools that use monochromatic sources are particularly limited in that sense, since for certain pitches and materials a small variation in line width might have virtually no effect on the reflectivity measured at 193, 248, 365 or 633 nanometers. The following figure illustrates a typical variation in the polarized reflectance spectra (R s and R p ) due to 40 nm variation in line width of Continues on page 4.

4 Page 4 Volume 23, Issue 7 Continued from page 3. Figure 4. Typical ACI trench structure. Figure 5. Typical ADI trench profile obtained using the technique described above. a 600 nm - pitch grating. Twenty Rs spectra and twenty Rp spectra are plotted - each one corresponding to a 2 nm increase in line width (from 280 nm to 320 nm). The maximum sensitivity to the change in width is observed at ~440 nm wavelength. At 193, 248, 365 and 633 nm wavelengths the variations would be simply impossible to resolve. Even at the optimal wavelength of ~440 nm a repeatable measurement would be difficult to accomplish due to low reflectivity and possible noise problems. Overlooking this issue may cause significant reduction in yield. Understanding this issue will lead to a search for an alternate metrology solution. In this case, instruments with the widest measurement wavelength range, variable measurement angle and variable polarization of sampling radiation will have the advantage over other tools. In other words, the most versatile instrument will occupy the top place in the list of possible metrology solutions. The use of transmittance spectra proved to be instrumental in improving the sensitivity of the measurement to minor (sub-nanometer) changes in the width of the trench. The study demonstrated that transmittance spectrum is more sensitive to the variation in line width, compared to the reflectance spectrum. The following figure illustrates a typical variation in the polarized transmittance spectra (T s and T p ) due to 40 nm variation in line width of a 600 nm - pitch grating. Twenty T s spectra and twenty T p spectra are plotted - each one corresponding to a 2 nm increase in line width (from 280 nm to 320 nm). Right away, the contrast with the previous graph is obvious. The variation in the spectral intensity is very high, compared to the variations in the reflectance spectra. Virtually any wavelength between 190 and 500 nm can be used to resolve the difference between the trenches of various line widths. The wavelengths of 193, 248, 440 and 465 nm are particularly sensitive to the variation and therefore are particularly useful. The discovery of this type of sensitivity opens new portals in CD metrology. The improved resolution makes it possible to detect Angstrom-level variations in trench width. This technique, however, would be impossible to use without a robust physically-valid analysis model, which would interpret the shape of the spectrum and quantify the grating geometry. The model of choice for the characterization of the optical properties of the materials present in the grating structure are the Forouhi-Bloomer dispersion relations, which provide a physically valid solution for the index of refraction and extinction coefficient spectra of thin films in the interband region. The most appropriate technique for the analysis of the grating geometry (trench depth, line width, sidewall angle, etc.) is the Rigorous Coupled Wave Analysis technique, introduced by Moharam 1 in Until now, however, this technique has never been applied to analyze measured transmittance spectra. The next section gives an overview of the RCWA method for the analysis of the transmittance spectra. III. RCWA method for transmittance spectra In RCWA method, as shown in Moharam s paper, for different polarization state of incident beam, Maxwell s equations in the grating region can be transferred as finding the eigenvalue of the matrix: Where And E is the matrix formed by the permittivity harmonic components (ε i ), with the i, j elements equals to ε i-j ; K x is a diagonal matrix with the elements equal to k xi /k 0. k xi is the wave vector of i-th diffraction order in x direction, and k 0 is the wave number in free space. For a grating with a thickness of d (in z-direction), electromagnetic field in the grating region can be written in Fourier expression as Where w im and q m are the elements of eigenvector matrix W and the positive sqare root of the eigenvalues of matrix A; V = WQ is the matrix with elements v im ; Q is the diagonal matrix with the elements q m. N is the truncation number of the diffraction orders. The boundary condition in the surface (z=0) and bottom of the grating (z=d) lead to Where R, T are vectors of reflectance and transmittance; C +, C - are vectors with the elements C +, m C- separately; X is a diagonal matrix m with the elements exp(-k 0 q m d); K I, K II are diagonal matrices with the elements k I,z i /k 0 (for s, or k I,z i /(k 0 n 2) for p-polarization), and k /k (for I II,zi 0 s, or k II,zi /(k 0 n 2) for p-polarization separately; I is the identity matrix; n, II I n II are the refractive index of the incident and substrate media; and For l=i, II separately. Let Where (1) (2) (3) (4) (5) (6) (7) (8) (9) (10)

5 Volume 23, Issue 7 Page 5 Figure 6. Schematic top view of the measured trench structures. Each square pad is a 2mm x 2mm grating array. Then the transmittance can be found by eq. (5), (6) as For the multi-layer problem, consider the approach of partial solution (in J. Opt. Soc. Ame. A/Vol. 12, No.5, 1995, p ), let W 0 = I, V 0 = jδi 0 f(θ), f 0 = I, g 0 = jk I, C - = R, b = δ, X = I; Where 0 0 i0 0 And keep the relation of eq.(8)~(11) for each layer, the transmittance can be found as Where L is the number of layers, in the l-th layer (l = 1,..., L), With the eq.(14), (15), reflectance for all the multi-layer diffraction grating with different polarization states can be found with a good data stability and converging rate. IV. Measurement method For the current study we used a spectrophotometer-based instrument, capable of collecting four continuous spectra during one measurment two polarized reflectance spectra (R s and R p ) and two polarized transmittance spectra (T s and T p ). The light source of the spectrophotometer was equipped with a rotating polarizer, facilitating TE and TM polarization of the measurement beam. The measurement wavelength range was from 190 nm to 1000 nm, with in one nanometer intervals. In general, the described method can be used to analyze any combination of polarized and unpolarized reflectance and transmittance spectra. In fact, before this study, the measurement of polarized transmittance spectra were not particularly instrumental in the characterization of small-pitch gratings, since the RCWA technique for the analysis of the measured data was not yet developed. Therefore, in the past, only reflectance spectra were used for the determination on the critical dimensions in small-pitch gratings, and the transmittance spectra were used strictly for the characterization of the optical properties of the materials used in the film structure. Addition of a transmittance spectrophotometer was originally intended to facilitate extra raw data, which helps to constrain the calculation model and provide more stable and accurate results. It turned out, however, that transmittance spectra do not only carry additional information about the structure, but are in general more useful in providing highresolution, high-sensitivity CD measurement, compared to the reflectance spectra. (11) (12) (13) (14) (15) After the raw data is collected, all four spectra are simultaneously analysed using the Forouhi-Bloomer dispersion relations, in conjunction with RCWA, to extract the values of n and k, film thickness, and trench dimensions. The analysis model generates calculated reflectance and transmittance spectra using the nominal parameters, and then optimizes the values, using nonlinear regression analysis in order to obtain the best match between the measured and calculated spectra. Each parameter in the model can be either varied or fixed at a known value. The following figure depicts a typical fit between four measured spectra and four calculated spectra, generated by the analysis software. Generally, it is not practical to vary the optical properties of the films present in the grating structure. In most cases n and k of the films can be obtained by collecting the measurements on the blanket areas of the sample. The determined optical properties then can be used in the model for the trench structure, reducing the number of variables in the model. Typically, in the case of the chromium, photoresist, and the phase shift materials (MoSi), the n and k spectra are premeasured from the uniform area and then fixed during the CD measurement. V. Application to the measurement of ACI photomasks In the current study, the method described above was used to measure the CD linearity on an ACI (After Cleaning Inspection) photomask. A typical ACI structure consists of a single patterned MoSi layer deposited on a fused silica substrate (see the figure below). During the etching process, the substrate is usually slightly overetched into (~30A). The parameter of interest at this stage of the process is the width of MoSi lines in the trench pattern. However, in the process of measurement, other parameters, such as n and k of the substrate and the MoSi layer, and trench depth are also determined. Furthermore, if desired, the method can be used to determine a detailed profile of the periodic grating structure. The following figure illustrates an example of such analysis applied to the characterization of the profile of the photoresist lines on chrome (ADI structure). The cross section of the same grating structure obtained using SEM is displayed on the right. For this particular study, an array of twenty-one grating structures was measured on an ACI photomask. The pitch of the grating structure was 600 nm. The nominal line widths varied from 280 nm to 320 nm with 2-nanometer interval. The following figure depicts the schematic top view of the measured grating arrays. The same structures were re-measured using a conventional CD- SEM. The following plot illustrates the correlation between the results obtained using the two techniques. It is evident that the results obtained using the new transmittance RCWA technique exhibit excellent correlation with a conventional CD-SEM. The major advantage of the optical technique, however, Continues on page 6.

6 Page 6 Volume 23, Issue 7 Continued from page 5. Figure 7. Correlation of the line width values obtained using the optical technique and the CD-SEM. Figure 8. Improvement in the repeatability of the CD measurement due to the use of transmittance spectra. is high throughput (several seconds per point) and versatility. Along with the line width, other parameters such as trench depth, optical properties of the MoSi and phase shift at 193 nm and 248 nm were obtained during the same measurement. Furthermore, due to the fact that the intensity of the transmitted measurement beam is about fives time higher than the intensity of the reflected measurement beam, the improved signal-to-noise ratio guarantees a much better repeatability of the results. The following table illustrates a typical improvement in the short-term load-unload repeatability of the ASI and binary Cron- Quartz masks. Evidently, the repeatability of the measured CD values improves due to the inclusion of the higher-intensity transmittance spectra in the analysis. VI. Summary For the first time Rigorous Coupled Wave Analysis (RCWA) has been applied to the analysis of the transmittance spectra for the determination of critical dimension (CD) of phase-shift photomasks. A spectrophotometer-based instrument (n&k R-T Scatterometer), capable of collecting four continuous spectra during one measurement - two polarized reflectance spectra (R s and R p ) and two polarized transmittance spectra (T s and T p ) was used for the measurement of the 600 nm - pitch gratings on an ACI mask. The light source of the spectrophotometer was equipped with a rotating polarizer, facilitating TE and TM polarization of the measurement beam. The measurement wavelength range was from 190 nm to 1000 nm, in one nanometer intervals. The use of transmittance spectra proved to be instrumental in improving the sensitivity of the measurement to minor (sub-nanometer) changes in the width of the trench. The linearity study using a new technique demonstrated an excellent correlation with a conventional CD-SEM measurements and an improved repeatability, compared to the traditional reflectance-only measurement. The advantages of the optical method are high throughput, non-destructive nature of the measurements and capability to measure a wider variety of structures pertinent to the photomask manufacturing process. VII. Acknowledgements We would like to thank Dr. Yo-Han Choi and Dr. Kyoung-Yoon Bang of Samsung Electronics, Korea, for providing the samples and CD-SEM results for the study. We would also like to thank Dr. Rahim Forouhi and Dr. George Li of n&k Technology for supervising the measurements and the analysis of the samples.

7 Volume 23, Issue 7 Page 7 N E W S

8 Page 8 Volume 23, Issue 7 Sponsorship Opportunities Sign up now for the best Photomask 2007 sponsorship opportunities. Contact: Sue Siegfried Tel: ssiegfried@spie.org Advertise in the BACUS News! The BACUS Newsletter is the premier publication serving the photomask industry. For information on how to advertise, contact: Sue Siegfried Tel: ssiegfried@spie.org BACUS Technical Meetings BACUS holds technical meetings in the Bay Area approximately every quarter, from 8:30 to 11:30 am. If you are interested in presenting a paper at this meeting, contact Robert (Bob) Naber, Cadence Design Systems, Inc., Tel: ; naber@cadence.com Industry Briefs Rohm and Haas Electronic Materials invests US$60 million in immersion litho tool set By Future Fab To remain competitive in the fast-paced world of lithography materials technology, Rohm and Haas Electronic Materials has said that it will invest US$60 million in leading-edge lithography equipment including ASML s latest immersion lithography tool, the TWINSCAN XT: 1900Gi, to support photoresist and antireflective coatings development. As a leading material supplier to the semiconductor industry, our ability to deliver advanced lithography materials is critical, especially as the industry moves down below the 45nm node, said Dr. Dominic Yang, business unit Director, Microelectronic Technologies. This investment will not only enable deep technical partnerships with the front runners in the Memory, Foundry and Logic segments, but will bring to these customers high quality products manufactured and tested using the best tools in the industry. The equipment investment also includes a 300mm coat/develop track system that is connected to the immersion tool as well as defect inspection and metrology tools, though the company did not state the suppliers of these systems. New development partnership focuses on 10nm e-beam capabilities By Future Fab A trilateral RD&E program between GenISys, JEOL and Cornell University s Nanoscale Science and Technology Facility has been working on improving direct write e-beam data preparation and electron process correction (nano-epc) technologies for 10nm-range structures. Findings of the Cornell-JEOL collaboration have enabled upgrades of the GenISys software Layout BEAMER, which now includes an algorithm that corrects printing artifacts of this discrete writing grid. They expect in the future to account for additional machine and process effects. The users of e-beam direct write need urgent solutions for advanced data preparation and correction for nanostructure applications. The strong cooperation of the equipment vendor, the user and the software vendor is key for these developments. We are very fortunate to be collaborating with JEOL and Cornell Nanoscale Science and Technology Facility, said Ulrich Hofmann, founder and general manager of GenISys. These organizations are pioneering the state of the art in nano-fabrication and provide the ideal forum for further development and extension of Layout BEAMER. The high flexibility, responsiveness and unique combination of software and e-beam application knowledge will enable GenISys to deliver the solutions the market is waiting for. 10nm small structures are fabricated with only a few pulses of the electron beam writer, creating a need for better uniformity, consistency and placement, according to the team. BACUS Corporate Members Inko Industrials Corporation To receive an announcements of these meetings, send an message to patw@spie.org; in the body of the message include the words subscribe info-bacus. STMicroelectronics to use Clear Shape for 65nm DFM requirements By Future Fab After a year-long evaluation period, STMicroelectronics has selected Clear Shape Technologies InShape and OutPerform DFM products for 65nm and below device tapouts. Our requirements for DFM solutions are extremely stringent, since we design high-performance, high-volume products for many applications such as mobile communications, computer peripherals and consumer electronics, said Philippe Magarshack, Front-End Technologies and Manufacturing Group Vice President and General Manager of Central CAD & Design Automation at STMicroelectronics. Clear Shape demonstrated excellent silicon-accurate results and performance. Their solutions will enable our IP and library developers to eliminate systematic variability from their designs thanks to silicon accurate lithography and OPC modeling, he added. Clear Shape claimed that its InShape product completed full-chip analysis in hours and that electrical characterization had a high correlation to actual silicon results via its OutPerform tool.

9 Join the premier professional organization Volume 23, Issue 7 Page 9 for mask makers and mask users! About the BACUS Group Founded in 1980 by a group of chrome blank users wanting a single voice to interact with suppliers, BACUS has grown to become the largest and most widely known forum for the exchange of technical information of interest to photomask and reticle makers. BACUS joined SPIE in January of 1991 to expand the exchange of information with mask makers around the world. The group sponsors an informative monthly meeting and newsletter, BACUS News. The BACUS annual Photomask Technology Symposium covers photomask technology, photomask processes, lithography, materials and resists, phase shift masks, inspection and repair, metrology, and quality and manufacturing management. Individual Membership Benefits include: Subscription to BACUS News (monthly) Subscription to Microlithography World (quarterly) Quarterly technical meetings in the Bay Area Reduced registration rates at BACUS Photomask Technology annual meeting Eligibility to hold office on BACUS Steering Committee spie.org/bacus-individual.xml Corporate Membership Benefits include: One Voting Member in the SPIE General Membership Subscription to BACUS News (monthly) One online SPIE Journal Subscription Exhibit Space discount of 8% at either the Photomask or Advanced Lithography Symposium Listed as a Corporate Member in the BACUS Monthly Newsletter spie.org/bacus-corporate.xml C a l e n d a r 2007 SPIE/BACUS Photomask Technology September Monterey Marriott & Monterey Conference Ctr. Monterey, California USA spie.org/pm 2008 The 24th European European Mask and Lithography Conference (EMLC 2008) January Hilton Hotel Dresden, Germany SPIE Advanced Lithography February San Jose McEnry Convention Center San Jose, California USA spie.org/al Photomask Japan April Hotel Pacifico Yokohama Yokohamna, Japan SPIE is an international society advancing an interdiciplinary approach to the science and application of light. International Headquarters P.O. Box 10, Bellingham, WA USA Tel: or Fax: customerservice@spie.org SPIE.org Shipping Address th St., Bellingham, WA USA 2 Alexandra Gate, Ffordd Pengam, Cardiff, CF24 2SA, UK Tel: Fax: spieeurope@spieeurope.org You are invited to submit events of interest for this calendar. Please send to lindad@spie.org; alternatively, or fax to SPIE.

10 Page 10 Volume 23, Issue 7 Left image: Courtesy of International Business Machines Corporation. Center image: Courtesy of AMTC. Innovation at Work Photomask is where equipment suppliers, lithographers, material manufacturers, researchers, and mask fabricators share their research, network, and exchange the latest information. Attend Photomask and join this integrated effort to look at factors relevant to design-to-wafer realization. Network with those in key areas impacting reticle technology. Register early and save! September 2007 Monterey Marriott and Monterey Conference Center Monterey, California, USA Sponsored by SPIE.org/photomask