Mr. Thomas Öström Profile

Thomas Öström

Manager Subsystem Development at Mycronic AB

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Publications (8)

Proceedings Article | 20 October 2006 Paper

Improved photomask accuracy with a high-productivity DUV laser pattern generator

Thomas Öström, Jonas Måhlén, Andrzej Karawajczyk, Mats Rosling, Per Carlqvist, Per Askebjer, Tord Karlin, Jesper Sallander, Anders Österberg

Proceedings Volume 6349, 63490Y (2006) https://doi.org/10.1117/12.686196

KEYWORDS: Photomasks, Spatial light modulators, Neodymium, Calibration, Deep ultraviolet, Image enhancement, Electron beam lithography, Raster graphics, Control systems, Optical lithography

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A strategy for sub-100 nm technology nodes is to maximize the use of high-speed deep-UV laser pattern generators, reserving e-beam tools for the most critical photomask layers. With a 248 nm excimer laser and 0.82 NA projection optics, the Sigma7500 increases the application space of laser pattern generators. A programmable spatial light modulator (SLM) is imaged with partially coherent optics to compose the photomask pattern. Image profiles are enhanced with phase shifting in the pattern generator, and features below 200 nm are reliably printed. The Sigma7500 extends the SLM-based architecture with improvements to CD uniformity and placement accuracy, resulting from an error budget-based methodology. Among these improvements is a stiffer focus stage design with digital servos, resulting in improved focus stability. Tighter climate controls and improved dose control reduce drift during mask patterning. As a result, global composite CD uniformity below 5 nm (3σ) has been demonstrated, with placement accuracy below 10 nm (3σ) across the mask. Self-calibration methods are used to optimize and monitor system performance, reducing the need to print test plates. The SLM calibration camera views programmed test patterns, making it possible to evaluate image metrics such as CD uniformity and line edge roughness. The camera is also used to characterize image placement over the optical field. A feature called ProcessEqualizer^TM has been developed to correct long-range CD errors arising from process effects on production photomasks. Mask data is sized in real time to compensate for pattern-dependent errors related to local pattern density, as well as for systematic pattern-independent errors such as radial CD signatures. Corrections are made in the pixel domain in the advanced adjustments processor, which also performs global biasing, stamp distortion compensation, and corner enhancement. In the Sigma7500, the mask pattern is imaged with full edge addressability in each writing pass, providing the means of additionally improving write time by reducing the number of exposure passes. Photomask write time is generally under two hours in the 2-pass mode, compared to three hours with 4-pass writing. With a through-the-lens alignment system and both grid matching and pattern matching capabilities, the tool is also suitable for 2^nd layer patterning in advanced PSM applications. Improvements in alignment algorithms and writing accuracy have resulted in first-to-second level overlay below 15 nm (mean+3σ).

Proceedings Article | 20 May 2006 Paper

Sigma7500: an improved DUV laser pattern generator addressing sub-100-nm photomask accuracy and productivity requirements

Henrik Sjöberg, Tord Karlin, Mats Rosling, Thomas Öström, Jonas Måhlén, Tom Newman

Proceedings Volume 6283, 628305 (2006) https://doi.org/10.1117/12.681731

KEYWORDS: Photomasks, Spatial light modulators, Neodymium, Image enhancement, Calibration, Deep ultraviolet, Optical lithography, Raster graphics, CCD cameras, Phase shifting

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Proceedings Article | 28 June 2005 Paper

Second level exposure for phase shift mask applications using an SLM-based DUV mask writer

Mahesh Chandramouli, Bob Olshausen, Yulia Korobko, Sven Henrichs, Ping Qu, Jian Ma, Bruce Auches, Damon Cole, Thomas Ostrom, Angela Beyerl, Robert Eklund, Raoul Zerne, Peter Goransson, Magnus Persson, Tom Newman

Proceedings Volume 5853, (2005) https://doi.org/10.1117/12.617359

KEYWORDS: Neodymium, Photomasks, Spatial light modulators, Deep ultraviolet, Electron beam lithography, Optical alignment, Quartz, Optical lithography, Chromium, Critical dimension metrology

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Proceedings Article | 16 June 2005 Paper

Second level exposure for advanced phase shift mask applications using the SLM-based Sigma7300 DUV mask writer

Thomas Ostrom, Angela Beyerl, Henrik Sjoberg, Tom Newman, Peter Hogfeldt

Proceedings Volume 5835, (2005) https://doi.org/10.1117/12.637276

KEYWORDS: Photomasks, Optical alignment, Deep ultraviolet, Spatial light modulators, Electron beam lithography, Optical lithography, Overlay metrology, Charge-coupled devices, Quartz, CCD cameras

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Proceedings Article | 28 May 2004 Paper

DOE manufacture with the DUV SLM-based Sigma7300 laser pattern generator

Peter Björnängen, Mats Ekberg, Thomas Öström, Hans Fosshaug, Johan Karlsson, Charles Björnberg, Fredrik Nikolajeff, Mikael Karlsson

Proceedings Volume 5377, (2004) https://doi.org/10.1117/12.535767

KEYWORDS: Diffractive optical elements, Diffraction, Spatial light modulators, Manufacturing, Optics manufacturing, Phase shift keying, Quartz, Refractive index, Photomasks, Stray light

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Proceedings Article | 28 May 2004 Paper

Airborne molecular contamination control in the micromirror SLM-based deep ultraviolet DUV SIGMA7300 laser pattern generator

Mats Ekberg, Hans Fosshaug, Thomas Ostrom, Peter Bjornangen, Thomas Utterback, Per-Uno Skotte, John Higley, David Ruede, Oleg Kishkovich

Proceedings Volume 5377, (2004) https://doi.org/10.1117/12.535833

KEYWORDS: Photomasks, Deep ultraviolet, Molecules, Chemical analysis, Climatology, Molecular lasers, Spatial light modulators, Contamination, Optical components, Contamination control

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Proceedings Article | 24 May 2004 Paper

PSM alignment for Sigma7300: signal quality and resist effects from using the writing DUV laser light, spatial light modulator, and a CCD camera as a measurement tool for 2:nd layer alignment metrology

Thomas Ostrom, Sten Lindau, Mats Ekberg, Hans Fosshaug, Raoul Zerne

Proceedings Volume 5375, (2004) https://doi.org/10.1117/12.535830

KEYWORDS: Reflectivity, Spatial light modulators, Optical alignment, Deep ultraviolet, Charge-coupled devices, Image quality, Quartz, CCD cameras, Autoregressive models, Antireflective coatings

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Proceedings Article | 14 May 2004 Paper

Influence of writing strategy on CD control for the spatial light modulator-based Sigma7300 DUV laser pattern generator

Hans Fosshaug, Per Askebjer, Johan Karlsson, Adisa Bajramovic, Kezhao Xing, Robert Eklund, Jonathan Walford, Mats Ekberg, Peter Hogfeldt, Thomas Öström

Proceedings Volume 5376, (2004) https://doi.org/10.1117/12.535821

KEYWORDS: Diffusion, Critical dimension metrology, Photomasks, Deep ultraviolet, Polymers, Printing, Spatial light modulators, Photoresist materials, Chemistry, Chemically amplified resists

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Showing 5 of 8 publications

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