Dr. Justin Hwu Profile

Dr. Justin Hwu

Sr. Staff Application Engineer at Hitachi High-Tech America Inc

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Publications (15)

SPIE Journal Paper | 12 August 2014 Open Access

Fabrication of servo-integrated template for 1.5 Teradot/inch² bit patterned media with block copolymer directed assembly

XiaoMin Yang, Shuaigang Xiao, Yautzong Hsu, HongYing Wang, Justin Hwu, Philip Steiner, Koichi Wago, Kim Lee, David Kuo

JM3, Vol. 13, Issue 03, 031307, (August 2014) https://doi.org/10.1117/12.10.1117/1.JMM.13.3.031307

KEYWORDS: Servomechanisms, Beam propagation method, Scanning electron microscopy, Quartz, Magnetism, Nanoimprint lithography, Etching, Optical lithography, Lithography, Directed self assembly

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SPIE Journal Paper | 2 August 2013 Open Access

Directed self-assembly for high-density bit-patterned media fabrication using spherical block copolymers

Shuaigang Xiao, XiaoMin Yang, Kim Lee, Justin Hwu, Koichi Wago, David Kuo

JM3, Vol. 12, Issue 03, 031110, (August 2013) https://doi.org/10.1117/12.10.1117/1.JMM.12.3.031110

KEYWORDS: Spherical lenses, Magnetism, Picosecond phenomena, Servomechanisms, Quartz, Beam propagation method, Lithography, Nanoimprint lithography, Reactive ion etching, Directed self assembly

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Proceedings Article | 3 April 2012 Paper

SEM metrology on bit patterned media nanoimprint template: issues and improvements

Justin Hwu, Sergey Babin, Peter Yushmanov

Proceedings Volume 8324, 83241F (2012) https://doi.org/10.1117/12.918064

KEYWORDS: Scanning electron microscopy, Metrology, Image processing, Nanoimprint lithography, Image analysis, Transmission electron microscopy, Statistical analysis, Signal processing, Process modeling, Beam propagation method

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SPIE Journal Paper | 1 October 2010

Mueller matrix measurement of asymmetric gratings

Jie Li, Justin Hwu, Yongdong Liu, Silvio Rabello, Zhuan Liu, Jiangtao Hu

JM3, Vol. 9, Issue 04, 041305, (October 2010) https://doi.org/10.1117/12.10.1117/1.3514708

KEYWORDS: Picosecond phenomena, Scatterometry, Atomic force microscopy, Nanoimprint lithography, Calibration, Spectroscopic ellipsometry, Scanning electron microscopy, Photoresist processing, Metrology, Polarization

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Proceedings Article | 2 April 2010 Paper

Application of analytic SEM to CD metrology at nanometer scale

Justin Hwu, Sergey Babin, Konstantin Bay

Proceedings Volume 7638, 76383O (2010) https://doi.org/10.1117/12.851106

KEYWORDS: Scanning electron microscopy, Image processing, Metrology, Transmission electron microscopy, Line width roughness, Image analysis, Monte Carlo methods, Process modeling, Critical dimension metrology, Quartz

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Proceedings Article | 11 December 2009 Paper

Scatterometry measurement of asymmetric gratings

Jie Li, Justin Hwu, Yongdong Liu, Silvio Rabello, Zhuan Liu, Jiangtao Hu

Proceedings Volume 7520, 75201B (2009) https://doi.org/10.1117/12.839821

KEYWORDS: Picosecond phenomena, Scatterometry, Atomic force microscopy, Lithography, Scatter measurement, Critical dimension metrology, Spectroscopic ellipsometry, Photoresist processing, Calibration, Metrology

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Proceedings Article | 11 December 2009 Paper

Optical critical dimension measurements for patterned media with 10's nm feature size

Yongdong Liu, Milad Tabet, Jiangtao Hu, Zhaoning Yu, Justin Hwu, Wei Hu, Sha Zhu, Gene Gauzner, Kim Lee, Shifu Lee

Proceedings Volume 7520, 75200H (2009) https://doi.org/10.1117/12.839523

KEYWORDS: Quartz, Scanning electron microscopy, Metrology, Critical dimension metrology, Atomic force microscopy, Ultraviolet radiation, Nanoimprint lithography, Lithography, Optical testing, Scanning transmission electron microscopy

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Proceedings Article | 23 September 2009 Paper

SEM CD metrology on nanoimprint template: an analytical SEM approach

Justin Hwu, Sergey Babin, Lorena Page, Alex Danilevsky, Andy Self, Kazuhiro Ueda, Shunzuke Koshihara, Koichi Wago, Kim Lee, David Kuo

Proceedings Volume 7488, 74881W (2009) https://doi.org/10.1117/12.830699

KEYWORDS: Scanning electron microscopy, Image processing, Image analysis, Metrology, Line width roughness, Critical dimension metrology, Monte Carlo methods, Transmission electron microscopy, Quartz, Process modeling

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Critical dimension metrology is the most needed feedback in nanofabrication and automatic CDSEM-based methods are by far the industrial standard for its well-established methodology and ease of programming and flexibility in measurement setup and operation. The dimensional measurements from SEMs consist of two steps, the first being the pixel based electron emission signal intensity profile generation and the second being the algorithm treatment on the generated intensity profile for the dimension determination. However, SEM metrology involves uncertainty of the measurement in the signal processing step, because the SEM signal formation is an extremely complex process depending on the pattern geometry, materials, detector setup, and beam voltage. Analytical SEMs are even less optimized for the task of quantitative metrology, especially at the CD ranging below 100 nm. In this work, we used an analytical SEM for CD metrology applications on quartz nanoimprint template from the perspective that only analytical SEM is accessible. The machine was tuned and beam characterization was done first to find the best reasonable condition for consistent manual operation using BEAMETR beam measurement pattern and software. The optimized beam condition set was then used for image collection on pitch pattern quartz template and the measurements were done using regular imaging processing and physical model based processing tool myCD. In order to discuss the spot size on the scan signal and the resulting influence on CD measurements, we used CHARIOT simulation software for simulated intensity profile as demonstration. The quartz template was then measured through a mask CDSEM for final data comparison. Selected sites were cross sectioned to reveal profile information as metrology comparison reference. Through our exercise, the metrology capability and fundamental limitation of analytical SEM operation with regular imaging processing was identified and the improvement using the physical modeling imaging process was verified.

Proceedings Article | 10 May 2005 Paper

The sidewall angle dependence of CDSEM measurements and its impact on CD process control

Justin Hwu, Homayoun Kiamanesh, Sukhbir Dulay, Peter Wilkens

Proceedings Volume 5752, (2005) https://doi.org/10.1117/12.600122

KEYWORDS: Critical dimension metrology, Algorithm development, Process control, Finite element methods, Metrology, Semiconducting wafers, Detection and tracking algorithms, Signal generators, Scanning electron microscopy, Signal processing

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Proceedings Article | 24 May 2004 Paper

The estimation of total measurement uncertainty in a multiple metrology tool environment

Justin Hwu, Thao Pham, Sukhbir Dulay, Andrew Lopez, Peter Wilkens

Proceedings Volume 5375, (2004) https://doi.org/10.1117/12.535526

KEYWORDS: Metrology, Process control, Error analysis, Statistical analysis, Environmental sensing, Statistical modeling, Overlay metrology, Algorithm development, Manufacturing, Nondestructive evaluation

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Proceedings Article | 26 June 2003 Paper

Challenges of implementing 193nm lithography in printing sub-70nm line patterns for thin film heads

Chun-Ming Wang, Justin Hwu, Timothy Minvielle

Proceedings Volume 5040, (2003) https://doi.org/10.1117/12.485420

KEYWORDS: Lithography, Head, Thin films, Printing, Bridges, Critical dimension metrology, Photomasks, Manufacturing, 193nm lithography, Sensors

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Proceedings Article | 2 June 2003 Paper

Measurement correlation and tool matching of multiple CD-SEMs

Justin Hwu, Sukhbir Dulay, Thao Pham

Proceedings Volume 5038, (2003) https://doi.org/10.1117/12.483757

KEYWORDS: Semiconducting wafers, Line scan image sensors, Smoothing, Critical dimension metrology, Deep ultraviolet, Algorithm development, Calibration, Photomasks, Process control, Signal to noise ratio

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A methodology is proposed to evaluate measurement correlation and matching feasibility between CDSEMs from different vendors in a multiple tool environment. Two CDSEMs from different vendors are used in this study. The measurement correlation and matching feasibility is identified through a series of steps. The pixel oversampling of both CDSEMs were first adjusted to the same extent in order to achieve the same scan pixel signal-to-noise ratio on both CDSEMs. Then the corresponding linescan smoothing and averaging were lowered but optimized with the precision criterion of less than 2 nm. The scan pixel magnification calibrations on both CDSEMs were traced back to an internal pitch standard. The corresponding measurement linearity was checked against a resolution mask from which wafers with pitch ranging from 400 to 800 nm were generated using a 248 nm stepper. The resulting scanning magnification correction factors for both CDSEMs in two scan orientations were determined for the follow-on measurement corrections on 248 nm resist focus exposure pattern (FEM) wafers and e-beam resist wafers obtained from e-beam lithography. The algorithms' characteristics between two CDSEMs were identified and they were adjusted to use only the information derived from the first linescan derivative in order to maintain maximum algorithm similiarity. The 120 nm process window on 248 nm resist wafers has a positive 1.6 nm offset from CDSEM A to B through focus. Both CDSEMs report the same process latitude for 110 nm process window identification. The measurement correlation study on e-beam resist shows offsets of negative 1.5 and 2 nm from CDSEM A to B, depending on which CDSEM is used first for the measurement sequence. Analysis-of-variance was used to analyze the measurement correlation. It is found that there is no significant difference in offsets generated regardless of which CDSEM is used first for performing the measurement for the 248 nm resist system. However, the offset generated for e-beam resist is dependent on measurement sequence. We conclude that CDSEMs from different vendors can be adjusted to maintain a constant offset over a CD variation range since after tuning all the factors mentioned both CDSEMs have very similar responses toward resist line secondary characteristics. Therefore these two CDSEMs are viewed as matched from a process development and process control prospective. All other CDSEMs in the same vendor group are then matched to each of the two bridged CDSEMs following the correposponding vendor's routine without any major procedure change.

Proceedings Article | 2 June 2000 Paper

Computer modeling of charging-induced electron beam deflection in electron beam lithography

Justin Hwu, Yeong-Uk Ko, David Joy

Proceedings Volume 3998, (2000) https://doi.org/10.1117/12.386477

KEYWORDS: Electron beams, Optical simulations, Computer simulations, Electron beam lithography, Electrodes, Monte Carlo methods, Mathematical modeling, Data modeling, Glasses, Computer programming

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Proceedings Article | 2 June 2000 Paper

Monte Carlo model of charging in resists in e-beam lithography

Yeong-Uk Ko, Justin Hwu, David Joy

Proceedings Volume 3998, (2000) https://doi.org/10.1117/12.386526

KEYWORDS: Electrons, Electron beam lithography, Monte Carlo methods, Electron beams, Manufacturing, Semiconductor manufacturing, Semiconductors, Control systems, Photomasks, Lithography

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Proceedings Article | 2 June 2000 Paper

Metrics of resolution and performance for CD-SEMs

David Joy, Yeong-Uk Ko, Justin Hwu

Proceedings Volume 3998, (2000) https://doi.org/10.1117/12.386444

KEYWORDS: Image resolution, Interference (communication), Signal to noise ratio, Spatial resolution, Scanning electron microscopy, Image analysis, Image enhancement, Image transmission, Microscopes, Electron microscopes

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