Dr. Stephen J. DeMoor Profile

Dr. Stephen J. DeMoor

SMTS CMOS1 Lithography at Texas Instruments Inc

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Publications (6)

Proceedings Article | 15 March 2006 Paper

Across wafer focus mapping and its applications in advanced technology nodes

Gary Zhang, Stephen DeMoor, Scott Jessen, Qizhi He, Winston Yan, Sopa Chevacharoenkul, Venugopal Vellanki, Patrick Reynolds, Joe Ganeshan, Jan Hauschild, Marco Pieters

Proceedings Volume 6154, 61540N (2006) https://doi.org/10.1117/12.657752

KEYWORDS: Semiconducting wafers, Sensors, Chemical mechanical planarization, Scanners, Back end of line, Monochromatic aberrations, Calibration, Process control, Front end of line, Etching

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The understanding of focus variation across a wafer is crucial to CD control (both ACLV and AWLV) and pattern fidelity on the wafer and chip levels. This is particularly true for the 65nm node and beyond, where focus margin is shrinking with the design rules, and is turning out to be one of the key process variables that directly impact the device yield. A technique based on the Phase-Shift Focus Monitor (PSFM) is developed to measure realistic across-wafer focus errors on materials processed in actual production flows. With this technique, we are able to extract detailed across-wafer focus performance at critical pattern levels from the front end of line (FEOL) all the way through the back end of line (BEOL). Typically, more than 8,000 data points are measured across a wafer, and the data are decomposed into an intra-field focus map, which captures the across chip focus variation (ACFV), and an inter-field focus map, which describes the across wafer focus variation (AWFV). ACFV and AWFV are then analyzed to understand various components in the overall focus error, including; across slit lens image field, reticle shape and dynamic scan components, local wafer flatness, wafer processing effect, pattern density, and edge die abnormality. The intra-field ACFV lens component is compared with TI's ScatterLith and ASML's FOCAL techniques. Results are consistent with the predictions based on the on-board lens aberration data. Inter-field AWFV is the most interesting, due to lack of detailed understanding of the process impact on scanner focus and leveling. PSFM data is used to characterize the effect of wafer processing such as etch, deposition, and CMP on across wafer focus control. Comparison and correlation of PSFM focus mapping with the wafer height and residual moving average (MA) maps generated by the scanner's optical leveling sensors shows a good match in general. Process induced focus errors are clearly observed on wafers of significant film stack variation and/or pattern density variation. Implications on total focus control and depth of focus (DOF) requirements for 65nm mass production are discussed in this paper using a quantitative pattern yield model. The same technique can be extended to immersion lithography.

Proceedings Article | 28 May 2004 Paper

Characterization of ACLV for advanced technology nodes using scatterometer-based lens fingerprinting technique

ChangAn Wang, Guohong Zhang, Stephen DeMoor, Colin Tan, John Ilzhoefer, Chris Atkinson, Chad Wickman, Steve Hansen, Bernd Geh, Donis Flagello, Mark Boehm

Proceedings Volume 5377, (2004) https://doi.org/10.1117/12.535829

KEYWORDS: Critical dimension metrology, Monochromatic aberrations, Scanners, Fiber optic illuminators, Lithography, Metrology, Semiconducting wafers, Lithographic illumination, Control systems, Solids

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Proceedings Article | 24 May 2004 Paper

Scanner overlay mix and match matrix generation: capturing all sources of variation

Stephen DeMoor, Jay Brown, John Robinson, Simon Chang, Colin Tan

Proceedings Volume 5375, (2004) https://doi.org/10.1117/12.534359

KEYWORDS: Scanners, Semiconducting wafers, Data modeling, Optical alignment, Overlay metrology, Error analysis, Matrices, Statistical modeling, Phase modulation, Metrology

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Proceedings Article | 26 June 2003 Paper

Scatterometer-based scanner fingerprinting technique (ScatterLith) and its applications in image field and ACLV analysis

Changan Wang, Gary Zhang, Stephen DeMoor, Mark Boehm, Michael Littau, Christopher Raymond

Proceedings Volume 5040, (2003) https://doi.org/10.1117/12.485434

KEYWORDS: Monochromatic aberrations, Scanners, Critical dimension metrology, Image analysis, Lithography, Image processing, Error analysis, Optical lithography, Manufacturing, Semiconducting wafers

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The ability to accurately, quickly and automatically fingerprint the lenses of advanced lithography scanners has always been a dream for lithographers. This is truly necessary to understand error sources of ACLV, especially when the optical lithography is pushed into 130 nm regimes and beyond. This dream has become a reality at Texas Instruments with the help of scatterometry. This paper describes the development and characterization of the scatterometer based scanner lens testing technique (ScatterLith) and its application in 193 nm and 248 nm scanner lens fingerprinting. The entire procedure includes a full field exposure through focus in a micro stepping mode, scatterometer measurement of focus matrix, image field analysis and mapping of lens curvature, astigmatism, spherical aberration, line-through pitch analysis and ACLV analysis (i.e. across chip line width variation). ACLV has been directly correlated with image field deviation, lens aberration and illumination source errors. Examples are given to illustrate its applications in accurate focus monitoring with enhanced capability of dynamic image field and lens signature mapping for the latest ArF and KrF scanners used in manufacturing environment for 130nm node and beyond. Analysis of CD variation across a full scanner field is done through a step-by-step image field correction procedure. ACLV contribution of each image field error can be quantified separately. The final across slit CD signature is further analyzed against possible errors from illumination uniformity, illumination pupil fill, and higher order projection lens aberrations. High accuracy and short cycle time make this new technique a very effective tool for in-line real time monitoring and scanner qualification. Its fingerprinting capability also provides lithography engineers a comprehensive understanding of scanner performance for CD control and tool matching. Its extendibility to 90nm and beyond is particularly attractive for future development and manufacturing requirements.

Proceedings Article | 2 June 2003 Paper

An improved method to determine optimal alignment sampling layouts

Simon Chang, Stephen DeMoor, Jay Brown, Chris Atkinson, Joshua Roberge

Proceedings Volume 5038, (2003) https://doi.org/10.1117/12.483662

KEYWORDS: Optical alignment, Overlay metrology, Semiconducting wafers, Chemical elements, Imaging systems, Metrology, Scanners, Data modeling, Roads, Critical dimension metrology

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Proceedings Article | 2 June 2000 Paper

Overlay metrology productivity and stability enhancements using an offline recipe database manager (RDM)

Stephen DeMoor, Robert Peters, Todd Calvert, Stephanie Hilbun, George Beck, Kristi Bushman, Russell Fields

Proceedings Volume 3998, (2000) https://doi.org/10.1117/12.386456

KEYWORDS: Databases, Overlay metrology, Semiconducting wafers, Manufacturing, Metrology, Pattern recognition, Chlorine, Optics manufacturing, Target recognition, Optical alignment

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