Mr. Dan Schurz Profile

Dan Schurz

Product Integration Manager at Veeco Instruments Inc

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Publications (13)

Proceedings Article | 10 May 2005 Paper

Dual side lithography measurement, precision, and accuracy

Daniel Schurz, Warren Flack, Robert Hsieh

Proceedings Volume 5752, (2005) https://doi.org/10.1117/12.598861

KEYWORDS: Semiconducting wafers, Metrology, Optical alignment, Lithography, Cameras, Manufacturing, Microelectromechanical systems, Image registration, Calibration, Precision measurement

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Proceedings Article | 24 May 2004 Paper

Dual side wafer metrology for micromachining applications

Dan Schurz, Warren Flack, Doug Anberg

Proceedings Volume 5375, (2004) https://doi.org/10.1117/12.535928

KEYWORDS: Semiconducting wafers, Metrology, Optical alignment, Cameras, Lithography, Tolerancing, Calibration, Imaging systems, Image registration, Micromachining

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Proceedings Article | 17 December 2003 Paper

Defect printability for high-exposure dose advanced packaging applications

Max Mikles, Warren Flack, Ha-Ai Nguyen, Dan Schurz

Proceedings Volume 5256, (2003) https://doi.org/10.1117/12.518160

KEYWORDS: Photoresist materials, Pellicles, Packaging, Reticles, Semiconducting wafers, Lithography, Particles, Electroplating, Semiconductors, Saturn

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Pellicles are used in semiconductor lithography to minimize printable defects and reduce reticle cleaning frequency. However, there are a growing number of microlithography applications, such as advanced packaging and nanotechnology, where it is not clear that pellicles always offer a significant benefit. These applications have relatively large critical dimensions and require ultra thick photoresists with extremely high exposure doses. Given that the lithography is performed in Class 100 cleanroom conditions, it is possible that the risk of defects from contamination is sufficiently low that pellicles would not be required on certain process layer reticles. The elimination of the pellicle requirement would provide a cost reduction by saving the original pellicle cost and eliminating future pellicle replacement and repair costs. This study examines the imaging potential of defects with reticle patterns and processes typical for gold-bump and solder-bump advanced packaging lithography. The test reticle consists of 30 to 90 μm octagonal contact patterns representative of advanced packaging reticles. Programmed defects are added that represent the range of particle sizes (3 to 30 μm) normally protected by the pellicle and that are typical of advanced packaging lithography cleanrooms. The reticle is exposed using an Ultratech Saturn Spectrum 300e² 1X stepper on wafers coated with a variety of ultra thick (30 to 100 μm) positive and negative-acting photoresists commonly used in advanced packaging. The experimental results show that in many cases smaller particles continue to be yield issues for the feature size and density typical of advanced packaging processes. For the two negative photoresists studied it appears that a pellicle is not required for protection from defects smaller than 10 to 15 μm depending on the photoresist thickness. Thus the decision on pellicle usage for these materials would need to be made based on the device fabrication process and the cleanliness of a fabrication facility. For the two positive photoresists studied it appears that a pellicle is required to protect from defects down to 3 μm defects depending on the photoresist thickness. This suggests that a pellicle should always be used for these materials. Since a typical fabrication facility would use both positive and negative photoresists it may be advantageous to use pellicles on all reticles simply to avoid confusion. The cost savings of not using a pellicle could easily be outweighed by the yield benefits of using one.

Proceedings Article | 27 December 2002 Paper

Pellicle life-testing for high-exposure dose applications

Dan Schurz, Warren Flack

Proceedings Volume 4889, (2002) https://doi.org/10.1117/12.467758

KEYWORDS: Pellicles, Reticles, Photoresist materials, Mercury, Semiconducting wafers, Packaging, Lithography, Lithographic illumination, Glasses, Excimer lasers

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There are an increasing number of microlithography applications such as advanced packaging, nanotechnology and thin film head production that require the use of thick photoresist materials. The exposure dose requirements for these applications dramatically increase as the photoresist thickness increases. For example, some positive acting novolak photoresists require exposures in excess of 5000 mJoules/cm² for 100 μm thick films. When a single reticle is used to pattern many wafers, a significant amount of light and heat energy is transferred from the lithography tool illumination source to the pellicle protecting the reticle image. In high volume production environments, a pellicle can be subjected to accumulated dosages exceeding 500 kJoules/cm² within a matter of weeks. Because thick photoresist applications benefit from using 1X broadband steppers with high wafer plane irradiance, life-testing results were reviewed for broadband pellicles designed for maximum transmission at g, h and i-line wavelengths of Hg. Historically, pellicle lifetime testing was typically carried out only to approximately 500 kJoules/cm² . While this test limit may have been sufficient for thin photoresist applications used in semiconductor applications, longer lifetime studies are required to determine pellicle durability for thick photoresist applications. In this study, life testing was performed on multiple pellicle films designed for broadband illumination, including nitrocellulose, cellulose acetate, cellulose ester and fluoropolymer films. Spectroscopic transmission at g, h and i-line was first measured on unexposed pellicles. The pellicles were attached to test reticles and exposed to high-energy doses on an Ultratech broadband stepper, accumulating up to 3000 kJoules/cm² . Transmission was periodically re-measured and the pellicle films were visually inspected for color change and any apparent physical damage. Results were compared to the expected optical properties for each film type, and recommendations are provided for the most appropriate fil type for high-energy applications. Of the six pellicles tested, the two fluoropolymer films showed substantially better transmission stability than the cellulose based films. Discoloration occurred on the cellulose films over the chrome to glass transition area of the test reticle field suggesting that heat in the chrome surface affects the chemical structure of the pellicle films, thereby changing their transmission properties.

Proceedings Article | 11 March 2002 Paper

Simulation study of reticle enhancement technology applications for 157-nm lithography

Dan Schurz, Warren Flack, Linard Karklin

Proceedings Volume 4562, (2002) https://doi.org/10.1117/12.458255

KEYWORDS: Lithography, Reticles, Resolution enhancement technologies, Optical proximity correction, Binary data, Phase shifting, Photomasks, Optical lithography, Photoresist materials, Manufacturing

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Proceedings Article | 22 January 2001 Paper

High-optical-density photomasks for large exposure applications

Dan Schurz, Warren Flack, Makoto Nakamura

Proceedings Volume 4186, (2001) https://doi.org/10.1117/12.410770

KEYWORDS: Reticles, Photoresist materials, Semiconducting wafers, Chromium, Photomasks, Absorption, Scanning electron microscopy, Ultraviolet radiation, Spectrophotometry, Absorbance

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Proceedings Article | 30 December 1999 Paper

Effects of mask error factor on process window capability

Dan Schurz, Warren Flack, Simon Cohen, Thomas Newman, Khiem Nguyen

Proceedings Volume 3873, (1999) https://doi.org/10.1117/12.373317

KEYWORDS: Critical dimension metrology, Reticles, Cadmium, Photomasks, Semiconducting wafers, Photoresist materials, Lithography, Computer aided design, Tolerancing, Scanning electron microscopy

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Proceedings Article | 18 December 1998 Paper

Characterization of OPC masks for thin-film head pole trimming applications

Warren Flack, Sylvia White, Calvin Ho, Dan Schurz, Fabio Consentino

Proceedings Volume 3546, (1998) https://doi.org/10.1117/12.332846

KEYWORDS: Photoresist materials, Optical proximity correction, Reticles, Head, Photomasks, Computer aided design, Manufacturing, Lithography, Thermal weapon sites, Semiconducting wafers

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Proceedings Article | 8 June 1998 Paper

Reticle defect printability and photoresist modeling of contact structures

Warren Flack, Dan Schurz, Richard Lee, Calvin Ho

Proceedings Volume 3332, (1998) https://doi.org/10.1117/12.308773

KEYWORDS: Photoresist materials, Reticles, Opacity, Lithography, Semiconducting wafers, Computer aided design, Optical lithography, 3D modeling, Optical proximity correction, Standards development

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Proceedings Article | 7 July 1997 Paper

Simulation of subhalfmicron-mask defect printability at 1X reticle magnification

Warren Flack, Gary Newman, Dan Schurz

Proceedings Volume 3050, (1997) https://doi.org/10.1117/12.275910

KEYWORDS: Reticles, Opacity, Semiconducting wafers, Critical dimension metrology, Data modeling, Lithography, Optical proximity correction, 3D metrology, Optical simulations, Photoresist materials

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There has been considerable attention given to the printability of reticle defects and their impact on wafer yields. Over the last year the printability risk from small defects increased due to the wider application of optical proximity correction structures and the inclusion of more phase shifting retictles. There have been several simulation studies on the printability of sub-halfmicron defects using lens and illumination parameters of 5X reduction steppers. Since submicron 1X projection systems are being incorporated into numerous fabricant lines, there is a clear need to determine if these system show similar sensitivity to sub- halfmicron defects as reduction steppers. Earlier experimental work examined the printability of several classes of sub-halfmicron 25 micrometers defects on a submicron 1X stepper. To extend this work, a 3D optical lithography simulation tool has been employed to predict the printablity of various reticle defect scenarios. Experimental data was used to validate the 3D simulator by comparing modeling data to SEM measurements of wafers exposed with a reticle containing programmed clear pinhole and opaque pindot defects. A statistically designed simulation study was performed to quantify the critical dimension variation resulting from defects of varying size, proximity to a feature edge and variation in the pitch of the impacted line/space features. An additional statistically designed simulation was then use to predict the printability behavior of defects relative to different features sizes over a range of numerical aperture and partial coherence settings applicable to a 1X lens design. Finally, the impact of defect length and width on printability were characterized for rectangular defects over a range of sizes. Overall, this analysis enhances the understanding of the relationship between reticle defects and 1X projection optics and allows for determination of optical reticle defect specifications for cost effective lithography applications.

Proceedings Article | 12 February 1997 Paper

Printability of 1X reticle defects for submicron design rules

Dan Schurz, Warren Flack, Gary Newman

Proceedings Volume 3236, (1997) https://doi.org/10.1117/12.301217

KEYWORDS: Reticles, Opacity, Lithography, Semiconducting wafers, Scanning electron microscopy, Computer aided design, Critical dimension metrology, Photoresist materials, Optical lithography, Optical simulations

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As the push for improved resolution in wafer lithography intensifies and 0.18 micrometer devices are nearing production, the potential impact of subhalf micron reticle defects has become a growing concern. There have been several studies on the printability of subhalf-micron defects on high resolution reduction photolithography equipment. These studies have been extended to 1X lithography systems and more recently to advanced sub-micron 1X steppers. Previous studies have indicated that 0.20 micrometer opaque and 0.25 micrometer clear pinhole defects were at the margins of adversely impacting 0.65 micrometer lithography on a 1X stepper. However, due to the limited number of defects at these sizes on the reticle, definitive conclusions on printability could not be drawn. An additional study, using a three dimensional (3D) optical lithography simulation program, has shown defect size, proximity to an adjacent feature, and feature pitch to be significant factors contributing to reticle defect printability. Using the simulation findings as a guide, a new reticle was designed to contain an increased number of clear pinhole and opaque defects in the 0.15 to 0.30 micrometer range located in multiple pitches of both horizontal and vertical line/space pairs. Defect printability was determined using a 1X i-line projection stepper with focus and exposure optimized for nominal critical dimensions of 0.65 micrometer. The reticle and wafer defects were measured using low voltage SEM metrology. Simulation and experimental results have shown that pitch is the most significant contributor in the printability of clear pinhole, opaque, square and aspect ratio defects. In general, the impact of defect proximity to an adjacent feature is less extreme than the effect of pitch, but is more pronounced for clear pinhole defects. This study suggests that simulation can be a useful tool to help lithographers understand the behavior of reticle defects for particular layout design parameters. Consequently, simulation can be used to develop realistic reticle defect specifications with mask vendors, and improve cost-effectiveness. Defect printability simulation can also be used to predict the effect of known defects on existing reticles to determine if these reticles should be used for manufacturing.

Proceedings Article | 27 December 1996 Paper

Subhalf-micron mask defect detectability and printability at 1X reticle magnification

Dan Schurz, Warren Flack, Gary Newman

Proceedings Volume 2884, (1996) https://doi.org/10.1117/12.262801

KEYWORDS: Reticles, Semiconducting wafers, Computer aided design, Inspection, Opacity, Manufacturing, Scanning electron microscopy, Lithography, Photomasks, Defect detection

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Proceedings Article | 8 December 1995 Paper

Chromium-based attenuated embedded phase-shift photomask blanks for use in 1X lithography

Dan Schurz, Elizabeth Tai, Franklin Kalk

Proceedings Volume 2621, (1995) https://doi.org/10.1117/12.228204

KEYWORDS: Photomasks, Semiconducting wafers, Phase shifts, Reticles, Manufacturing, Etching, Lithography, Quartz, Optical lithography, Inspection

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Showing 5 of 13 publications

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