Mr. Sohan S. Mehta Profile

Sohan S. Mehta

Principal Member of Technical Staff ( PMTS) at GLOBALFOUNDRIES Inc.

SPIE Involvement:

Author

Area of Expertise:

Lithography process design interaction , EUV , Multiple patterning ( LELE,LELELE, SADP) , Defectivity analysis and improvement , Thick film PSPI process , Immersion lithography and NTD

Profile Summary

Sohan Mehta is currently PMTS in the advanced lithography group at the GLOBALFOUNDRIES Inc. Malta, NY, USA. He earned his MS degree in Applied Optics from the Indian Institute of Technology(IIT) Delhi, India in 1997.He has published over 40 papers ( lithography field) in prestigious conferences and journals including invited papers.Sohan has filed 8 US patents and 2 trade secrets in advanced lithography. He is serving as a reviewer for several journals in lithography area. Sohan has been working in lithography process development for 20 years which includes experience with Micron DRAM Singapore,IME (research institute) Singapore, IBM East Fishkill and Globalfoundries Malta,NY.
His current focus is NTD process development, process- design interaction, multiple patterning, defectivity improvements and thick film PSPI process.

Publications (21)

Proceedings Article | 13 March 2018 Presentation + Paper

Presentation + Paper

Thick photosensitive polyimide film side wall angle variability and scum improvement for IC packaging stress control

Sohan Singh Mehta, Marco Yeung, Fahad Mirza, Thiagarajan Raman, Travis Longenbach, Justin Morgan, Mark Duggan, Rio Soedibyo, Sean Reidy, Mohamed Rabie, Jae Kyu Cho, C. Premachandran, Danish Faruqui

Proceedings Volume 10586, 1058612 (2018) https://doi.org/10.1117/12.2297360

KEYWORDS: Back end of line, Packaging, Copper, Silicon, Modulation, Semiconducting wafers, 3D modeling, Finite element methods, Reliability, Metals

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Proceedings Article | 28 March 2017 Presentation + Paper

Presentation + Paper

High-throughput electrical characterization for robust overlay lithography control

Devender Devender, Xumin Shen, Mark Duggan, Sunil Singh, Jonathan Rullan, Jae Choo, Sohan Mehta, Teck Jung Tang, Sean Reidy, Jonathan Holt, Hyung Woo Kim, Robert Fox, D. K. Sohn

Proceedings Volume 10145, 101450K (2017) https://doi.org/10.1117/12.2260707

KEYWORDS: Overlay metrology, Back end of line, Process control, Lithography, Semiconductors, Semiconductor manufacturing, Resistance, Reliability, Photomasks, Image processing, Metals, Optical lithography

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Proceedings Article | 20 March 2015 Paper

Paper

Process variation challenges and resolution in the negative-tone develop double patterning for 20nm and below technology node

Sohan Mehta, Lakshmi Ganta, Vikrant Chauhan, Yixu Wu, Sunil Singh, Chia Ann, Lokesh Subramany, Craig Higgins, Burcin Erenturk, Ravi Srivastava, Paramjit Singh, Hui Peng Koh, David Cho

Proceedings Volume 9425, 94250B (2015) https://doi.org/10.1117/12.2087546

KEYWORDS: Critical dimension metrology, Binary data, Double patterning technology, Etching, Photomasks, Photoresist processing, Nanoimprint lithography, Image processing, Optical lithography, Neodymium

Read Abstract +

Immersion based 20nm technology node and below becoming very challenging to chip designers, process and integration due to multiple patterning to integrate one design layer . Negative tone development (NTD) processes have been well accepted by industry experts for enabling technologies 20 nm and below. 193i double patterning is the technology solution for pitch down to 80 nm. This imposes tight control in critical dimension(CD) variation in double patterning where design patterns are decomposed in two different masks such as in litho-etch-litho etch (LELE). CD bimodality has been widely studied in LELE double patterning. A portion of CD tolerance budget is significantly consumed by variations in CD in double patterning.

The objective of this work is to study the process variation challenges and resolution in the Negative Tone Develop Process for 20 nm and Below Technology Node. This paper describes the effect of dose slope on CD variation in negative tone develop LELE process. This effect becomes even more challenging with standalone NTD developer process due to q-time driven CD variation. We studied impact of different stacks with combination of binary and attenuated phase shift mask and estimated dose slope contribution individually from stack and mask type. Mask 3D simulation was carried out to understand theoretical aspect. In order to meet the minimum insulator requirement for the worst case on wafer the overlay and critical dimension uniformity (CDU) budget margins have slimmed. Besides the litho process and tool control using enhanced metrology feedback, the variation control has other dependencies too. Color balancing between the two masks in LELE is helpful in countering effects such as iso-dense bias, and pattern shifting. Dummy insertion and the improved decomposition techniques [2] using multiple lower priority constraints can help to a great extent. Innovative color aware routing techniques [3] can also help with achieving more uniform density and color balanced layouts.

Proceedings Article | 18 March 2015 Paper

Paper

Investigating deprotection-induced shrinkage and retro-grade sidewalls in NTD resists

Thomas Pistor, Chenchen Wang, Yan Wang, Lei Yuan, Jongwook Kye, Yixu Wu, Sohan Mehta, Paul Ackmann

Proceedings Volume 9426, 94260T (2015) https://doi.org/10.1117/12.2087376

KEYWORDS: Scanning electron microscopy, Semiconducting wafers, Electrons, Signal attenuation, Atomic force microscopy, Photoresist materials, Photomasks, Distortion, Atrial fibrillation, Panoramic photography

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Proceedings Article | 17 April 2014 Paper

Paper

Integration of an EUV metal layer: a 20/14nm demo

Craig Higgins, Erik Verduijn, Xiang Hu, Liang Wang, Mandeep Singh, Jerome Wandell, Sohan Mehta, Jean Raymond Fakhoury, Mark Zaleski, Yi Zou, Hui Peng Koh, Pawitter Mangat

Proceedings Volume 9048, 90481Q (2014) https://doi.org/10.1117/12.2048285

KEYWORDS: Photomasks, Extreme ultraviolet, Semiconducting wafers, Extreme ultraviolet lithography, Metals, Optical lithography, Optical proximity correction, Overlay metrology, Deep ultraviolet, Inspection

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Proceedings Article | 2 April 2014 Paper

Paper

Evaluation of lens heating effect in high transmission NTD processes at the 20nm technology node

Bumhwan Jeon, Sam Lee, Lokesh Subramany, Chen Li, Shyam Pal, Sheldon Meyers, Sohan Mehta, Yayi Wei, David Cho

Proceedings Volume 9050, 90501U (2014) https://doi.org/10.1117/12.2034206

KEYWORDS: Semiconducting wafers, Reticles, Calibration, Photomasks, Critical dimension metrology, Source mask optimization, Computational modeling, Optical lithography, Wavefronts, Overlay metrology

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Proceedings Article | 18 April 2013 Paper

Paper

High order wafer alignment for 20nm node logic process

Bumhwan Jeon, Shyam Pal, Sohan Mehta, Subramany Lokesh, Yun Tao Jiang, Chen Li, Mark Yelverton, Yayi Wei

Proceedings Volume 8681, 868110 (2013) https://doi.org/10.1117/12.2010709

KEYWORDS: Semiconducting wafers, Optical alignment, Distortion, Overlay metrology, Annealing, Transistors, Logic, Laser processing, Lithography, Semiconductor manufacturing

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Proceedings Article | 29 March 2013 Paper

Paper

Investigation of trench and contact hole shrink mechanism in the negative tone develop process

Sohan Singh Mehta, Craig Higgins, Vikrant Chauhan, Shyam Pal, Hui Peng Koh, Jean Raymond Fakhoury, Shaowen Gao, Lokesh Subramany, Salman Iqbal, Bumhwan Jeon, Pedro Morrison, Chris Karanikas, Yayi Wei, David Cho

Proceedings Volume 8682, 86820O (2013) https://doi.org/10.1117/12.2012331

KEYWORDS: Diffusion, Critical dimension metrology, Polymers, Photoresist processing, Image processing, Manufacturing, Lithography, Optical lithography, Data modeling, Modulation

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Proceedings Article | 29 March 2013 Paper

Paper

20nm VIA BEOL patterning challenges

Chien-Hsien Lee, Sohan Singh Mehta, Wontae Hwang, Hui Husan Tsai, Michael Anderson, Yayi Wei, Matthew Herrick, Xiang Hu, Bumhwan Jeon, Shyam Pal

Proceedings Volume 8682, 86820D (2013) https://doi.org/10.1117/12.2011843

KEYWORDS: Etching, Optical lithography, Reactive ion etching, Critical dimension metrology, Back end of line, Semiconducting wafers, Photomasks, Double patterning technology, Dielectrics, Metals

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Proceedings Article | 23 March 2012 Paper

Paper

Computational study of line tip printability of sub-20-nm technology

Lei Yuan, Thomas Wallow, Deniz Civay, Linus Jang, Jongwook Kye, Harry Levinson, Sohan Singh, Mark Kelling

Proceedings Volume 8322, 832229 (2012) https://doi.org/10.1117/12.915868

KEYWORDS: Printing, Extreme ultraviolet, Optical lithography, Lithography, Extreme ultraviolet lithography, Photomasks, Lithographic illumination, Double patterning technology, Line edge roughness, Metals

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Proceedings Article | 20 March 2012 Paper

Paper

Assessment of negative tone development challenges

Sohan Mehta, Yongan Xu, Guillaume Landie, Vikrant Chauhan, Sean Burns, Peggy Lawson, Bassem Hamieh, Jerome Wandell, Martin Glodde, Yu Yang Sun, Mark Kelling, Alan Thomas, Jeong Soo Kim, James Chen, Hirokazu Kato, Chiahsun Tseng, Chiew-Seng Koay, Yoshinori Matsui, Martin Burkhardt, Yunpeng Yin, David Horak, Shyng-Tsong Chen, Yann Mignot, Yannick Loquet, Matthew Colburn, John Arnold, Terry Spooner, Lior Huli, Dave Hetzer, Jason Cantone, Shinichiro Kawakami, Shannon Dunn

Proceedings Volume 8325, 832506 (2012) https://doi.org/10.1117/12.917560

KEYWORDS: Semiconducting wafers, Polymers, Optical proximity correction, Reactive ion etching, Etching, Scanning electron microscopy, Neodymium, Photoresist developing, Image processing, Roads

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Proceedings Article | 16 March 2009 Paper

Paper

C-quad polarized illumination for back end thin wire: moving beyond annular illumination regime

Sohan Mehta, Hyung-Rae Lee, Bassem Hamieh, Chidam Kallingal, Itty Matthew, Ramya Viswanathan, Derren Dunn

Proceedings Volume 7274, 72742Y (2009) https://doi.org/10.1117/12.814296

KEYWORDS: Polarization, Line edge roughness, Optical lithography, Semiconducting wafers, Diffraction, Fiber optic illuminators, Fourier transforms, Critical dimension metrology, Lithography, Reticles

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Proceedings Article | 1 April 2008 Paper

Paper

Reflectivity-induced variation in implant layer lithography

Todd Bailey, Greg McIntyre, Bidan Zhang, Ryan Deschner, Sohan Mehta, Won Song, Hyung-Rae Lee, Yu Hue, MaryJane Brodsky

Proceedings Volume 6924, 69244F (2008) https://doi.org/10.1117/12.773102

KEYWORDS: Critical dimension metrology, Oxides, Reflectivity, Lithography, Semiconducting wafers, Photomasks, Chemical mechanical planarization, Silicon, Control systems, Etching

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SPIE Journal Paper | 1 April 2005

Intensity imbalance in phase shift masks and correction by multiple exposures

Moitreyee Mukherjee-Roy, Navab Singh, Sohan Mehta, Yasuki Kimura, Hideki Suda, Kazunori Nagai

JM3, Vol. 4, Issue 02, 023004, (April 2005) https://doi.org/10.1117/12.10.1117/1.1898043

KEYWORDS: Photomasks, Phase shifts, Monochromatic aberrations, Reticles, Diffraction, Critical dimension metrology, Cadmium, Scattering, Optical lithography, Semiconducting wafers

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Proceedings Article | 20 December 2004 Paper

Paper

New fabrication technology for photonic crystal waveguides

Sohan Singh Mehta, B. Ramana Murthy, Zhao Hui, * Suryani, Wei Ji, Mahadevan Iyer, My Doan

Proceedings Volume 5577, (2004) https://doi.org/10.1117/12.567602

KEYWORDS: Photonic crystals, Etching, Amorphous silicon, Lithography, Silicon, Optical lithography, Deep ultraviolet, Reticles, Scanning electron microscopy, Photomasks

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Proceedings Article | 20 December 2004 Paper

Paper

Spot size mode converter for efficient coupling to SiN waveguides

My Doan, Chi Tsang, Badam Ramana Murthy, Babu Narayanan, Chang Kuo Chang, Sohan Singh Mehta, Kuan Yap, Desmond Lim

Proceedings Volume 5577, (2004) https://doi.org/10.1117/12.567578

KEYWORDS: Waveguides, Fiber couplers, Silicon, Cladding, Etching, Wave propagation, Clocks, Photonic integrated circuits, Single mode fibers, Structured optical fibers

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Proceedings Article | 28 May 2004 Paper

Paper

Key challenges in across-pitch 0.33-k1 trench patterning using hybrid mask

Navab Singh, Moitreyee Mukherjee-Roy, Sohan Mehta, Hideki Suda, Takao Kubota, Yasuki Kimura, Hiroshi Kinoshita

Proceedings Volume 5377, (2004) https://doi.org/10.1117/12.547729

KEYWORDS: Photomasks, Optical lithography, Etching, Modulation, Phase shifts, Lithography, Binary data, Scanners, Manufacturing, Scanning electron microscopy

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Proceedings Article | 24 May 2004 Paper

Paper

Alignment in chromeless masks

Moitreyee Mukherjee-Roy, Navab Singh, Sohan Mehta, Hideki Suda, Takao Kubota, Yasuki Kimura, Hiroshi Kinoshita

Proceedings Volume 5375, (2004) https://doi.org/10.1117/12.538224

KEYWORDS: Scanning electron microscopy, Overlay metrology, Monochromatic aberrations, Optical lithography, Reticles, Photomasks, Etching, Mask making, Phase shifts, Structural design

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Proceedings Article | 3 May 2004 Paper

Paper

Patterning sub-50-nm Fin-FET using KrF lithography tool

Navab Singh, S. Jagar, Sohan Mehta, Moitreyee Mukherjee Roy, Rakesh Kumar, N. Balasubramanian

Proceedings Volume 5379, (2004) https://doi.org/10.1117/12.536040

KEYWORDS: Directed energy weapons, Optical lithography, Photomasks, Lithography, Field effect transistors, Semiconducting wafers, Electron beam lithography, Reticles, Scanning electron microscopy, Scanners

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Proceedings Article | 26 June 2003 Paper

Paper

Impact of scattering bars in damascene trench patterning

Sohan Mehta, Navab Singh, Moitreyee Mukherjee-Roy, Rakesh Kumar

Proceedings Volume 5040, (2003) https://doi.org/10.1117/12.485377

KEYWORDS: Scattering, Critical dimension metrology, Binary data, Optical lithography, Photomasks, Reticles, Semiconducting wafers, Phase shifts, Modulation, Diffraction

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Proceedings Article | 2 June 2003 Paper

Paper

Evaluation of alignment target designs for Cu and low-K dual damascene processes

Moitreyee Mukherjee-Roy, Navab Singh, Sohan Mehta, Wai Chik, Chin Tiong Sim, Francis Cheong

Proceedings Volume 5038, (2003) https://doi.org/10.1117/12.482800

KEYWORDS: Optical alignment, Semiconducting wafers, Thin film coatings, Dielectrics, Signal processing, Photomasks, Overlay metrology, Sensors, Copper, Etching

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Showing 5 of 21 publications

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