Mr. Bhardwaj S. Durvasula Profile

Bhardwaj S. Durvasula

SPIE Involvement:

Author

Area of Expertise:

Mask Data Preparation , Mask Process Correction , Computational Geometry

Profile Summary

I have an experience of over 10 years in the MDP (Mask Data Preparation) and MPC (Mask Process Correction) domains, primarily spent solving vast amounts of computational geometry and large data handling problems. I am currently working on the Calibre engine in Mentor. My ongoing research includes understanding the physics of lithography (because I need it), the statistical analysis of big data (because I use it), and machine learning (because every else is doing it).

Publications (16)

Proceedings Article | 26 August 2024 Paper

Paper

Integration of E-beam mask writer corrections in MPC applications

Ingo Bork, Rachit Sharma, Malavika Sharma, Archana Rajagopalan, Bhardwaj Durvasula, Kushlendra Mishra, Mary Zuo

Proceedings Volume 13177, 131770B (2024) https://doi.org/10.1117/12.3034234

KEYWORDS: Backscatter, Printing, Scattering, Forward error correction, Critical dimension metrology, Calibration, Etching, Photomasks, Photomask modeling

Read Abstract +

Critical Dimension Uniformity (CDU) of photomasks written with 50 kV e-beam writers is very sensitive to scattering and mask process effects such as etch loading. The interaction distances of those effects vary by about 6 orders of magnitude and range from around 10 nm to around 10 mm. With the introduction of 50 kV e-beam writers, tool manufacturers also developed methods for compensating the most significant scattering effects, namely backscattering, often called PEC for Proximity Effect Correction and fogging (also called FEC for Fogging Effect Correction). E-beam writers, including the most advanced multi-beam writers, use local dose modulation of the exposure dose as described in [1]-[3] to compensate for those longer-range scattering effects. This method works reasonably well for older technology nodes but starts to be a limiting factor for most advanced EUV masks which have to meet very high CDU specifications. The reason is that the Critical Dimension (CD) response to dose is not constant across different mask shapes. For example, very small features like sub-resolution assist features (SRAFs) have a higher ΔCD/ΔDose response than larger features, since smaller features have a more gradual image edge slope. So far it has not been reported in the literature that Mask Process Correction (MPC) applications take the e-beam writer corrections into account when correcting for shorter-range non-linearity effects. Ref. [4] describes an attempt to combine forward and backscatter compensation as an off-tool MPC application where all corrections seem to be achieved via dose modulation. This paper describes a method for integrating the e-beam writer dose modulation into the MPC engine, so that the actual exposure dose at any given location on the mask is taken into account when applying shape based, short-range MPC. With this extension of MPC, a fully consistent short- and long-range correction is possible, even when the actual long-range corrections are applied on the e-beam writer and not directly during the offline MPC step.

Proceedings Article | 21 November 2023 Presentation + Paper

Presentation + Paper

Integration of e-beam mask writer corrections in MPC applications

Ingo Bork, Rachit Sharma, Malavika Sharma, Archana Rajagopalan, Bhardwaj Durvasula, Kushlendra Mishra, Mary Zuo

Proceedings Volume 12751, 127510Y (2023) https://doi.org/10.1117/12.2688502

KEYWORDS: Modulation, Scattering, SRAF, Photomask technology, Backscatter, Photomasks, Manufacturing, Forward error correction, Extreme ultraviolet, Etching

Read Abstract +

Critical Dimension Uniformity (CDU) of photomasks written with 50 kV e-beam writers is very sensitive to scattering and mask process effects such as etch loading. The interaction distances of those effects vary by about 6 orders of magnitude and range from around 10 nm to around 10 mm. With the introduction of 50 kV e-beam writers, tool manufacturers also developed methods for compensating the most significant scattering effects, namely backscattering, often called PEC for Proximity Effect Correction and fogging (also called FEC for Fogging Effect Correction). E-beam writers, including the most advanced multi-beam writers, use local dose modulation of the exposure dose as described in [1]-[3] to compensate for those longer-range scattering effects. This method works reasonably well for older technology nodes but starts to be a limiting factor for most advanced EUV masks which have to meet very high CDU specifications. The reason is that the Critical Dimension (CD) response to dose is not constant across different mask shapes. For example, very small features like sub-resolution assist features (SRAFs) have a higher ΔCD/ΔDose response than larger features, since smaller features have a more gradual image edge slope. So far it has not been reported in the literature that Mask Process Correction (MPC) applications take the e-beam writer corrections into account when correcting for shorter-range non-linearity effects. Ref. [4] describes an attempt to combine forward and backscatter compensation as an off-tool MPC application where all corrections seem to be achieved via dose modulation. This paper describes a method for integrating the e-beam writer dose modulation into the MPC engine, so that the actual exposure dose at any given location on the mask is taken into account when applying shape based, short-range MPC. With this extension of MPC, a fully consistent short- and long-range correction is possible, even when the actual long-range corrections are applied on the e-beam writer and not directly during the offline MPC step.

Proceedings Article | 21 November 2023 Presentation + Paper

Presentation + Paper

Multibeam fracture flow based on multigon format input

Apurva Bajpai, Rachit Sharma, Bhardwaj Durvasula, Ranganadh Peespati, Sayalee Gharat, Stephen Kim

Proceedings Volume 12751, 127510A (2023) https://doi.org/10.1117/12.2687753

KEYWORDS: Process modeling, Photomasks, Optical lithography, Lithography, Data conversion, Extreme ultraviolet, Data processing, Contour modeling, Advanced patterning

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Proceedings Article | 21 November 2023 Presentation + Paper

Presentation + Paper

Opportunities, challenges, and applications of native curvilinear data representation in post-tape-out flows

Bhardwaj Durvasula, Sayalee Gharat, Ranganadh Peesapati, Archana Rajagopalan, Rachit Sharma, Stephen Kim, Ingo Bork

Proceedings Volume 12751, 1275107 (2023) https://doi.org/10.1117/12.2687645

KEYWORDS: Optical proximity correction, Lithography, Algorithm development, Photomasks, Industry

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Proceedings Article | 16 September 2022 Paper

Paper

Status of curvilinear data format working group

Jin Choi, Soo Ryu, Sukho Lee, Minah Kim, Sanghee Lee, Peter Buck, Bhardwaj Durvasula, Sayalee Gharat, Vlad Liubich

Proceedings Volume 12325, 1232508 (2022) https://doi.org/10.1117/12.2641557

KEYWORDS: Photomasks, Optical proximity correction, Extreme ultraviolet, Optical lithography, Mask making

Read Abstract +

SPIE Journal Paper | 1 November 2021 Open Access

Open Access

Study on various curvilinear data representations and their impact on mask and wafer manufacturing

Jin Choi, Soo Ryu, Sukho Lee, Minah Kim, JoonSoo Park, Peter Buck, Ingo Bork, Bhardwaj Durvasula, Sayalee Gharat, Nageswara Rao, Ravi Pai, Sandeep Koranne, Alexander Tritchkov

JM3, Vol. 20, Issue 04, 041403, (November 2021) https://doi.org/10.1117/12.10.1117/1.JMM.20.4.041403

KEYWORDS: Photomasks, Tolerancing, Optical proximity correction, Semiconducting wafers, Manufacturing, Extreme ultraviolet, Vestigial sideband modulation, Extreme ultraviolet lithography, Scanning electron microscopy, Lithography

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Proceedings Article | 22 October 2021 Presentation + Paper

Presentation + Paper

Curvature based fragmentation for curvilinear mask process correction

Ingo Bork, Peter Buck, Bhardwaj Durvasula, Vlad Liubich, Nageswara Rao, Rachit Sharma, Mary Zuo

Proceedings Volume 11855, 118550R (2021) https://doi.org/10.1117/12.2601032

KEYWORDS: Photomasks, SRAF, Optical proximity correction, Semiconducting wafers, Solids, Image segmentation, Data corrections, Data processing, Tolerancing, Lithography

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Proceedings Article | 12 October 2021 Presentation + Paper

Presentation + Paper

Using curvature-based pre-bias to reduce number of iterations in curvilinear mask process correction

Zhiheng (Mary) Zuo, Malavika Sharma, Ingo Bork, Bhardwaj Durvasula, Peter Buck

Proceedings Volume 11855, 118550Q (2021) https://doi.org/10.1117/12.2600959

KEYWORDS: Computational lithography, Photomasks, Optical proximity correction, Process modeling, Model-based design, Manufacturing

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Proceedings Article | 22 February 2021 Presentation + Paper

Presentation + Paper

A study on various curvilinear data representations and their impact on mask manufacturing flow

Sayalee Gharat, Bhardwaj Durvasula, Ravi Pai, Peter Buck, Sandeep Koranne, Alexander Tritchkov

Proceedings Volume 11613, 116130B (2021) https://doi.org/10.1117/12.2588374

KEYWORDS: Photomasks, Manufacturing, Semiconducting wafers, Mask making, Optics manufacturing, Extreme ultraviolet lithography, EUV optics

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Proceedings Article | 22 February 2021 Presentation + Paper

Presentation + Paper

Curvilinear data format working group for MBMW era

Jin Choi, Soo Ryu, Sukho Lee, Minah Kim, JoonSoo Park, Buck Peter, Ingo Bork, Bhardwaj Durvasula, Sayalee Gharat, Nageswara Rao

Proceedings Volume 11610, 116100S (2021) https://doi.org/10.1117/12.2587109

KEYWORDS: Optical proximity correction, Mask making, Electronic design automation

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Proceedings Article | 16 October 2019 Presentation + Paper

Presentation + Paper

Creating nonideality: enabling cross-platform process matching solutions with MPC (and a lot of hard work)

Charles Whiting, Ingo Bork, Peter Buck, Robin Chia, Bharadwaj Durvasula, Daniel Hill, Gazi Huda, Ken Jantzen, Matthew Leuthold, Jianliang Li, Joerg Mellmann, Kushlendra Mishra, Jed Rankin, Nageswara Rao, Malavika Sharma, Rachit Sharma, Adam Smith, Michaela Wentz

Proceedings Volume 11148, 1114805 (2019) https://doi.org/10.1117/12.2538347

KEYWORDS: Photomasks, Data modeling, Optical proximity correction, Critical dimension metrology, Calibration, Lithography, Semiconducting wafers, Manufacturing, Opacity, Etching

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Proceedings Article | 3 October 2019 Paper

Paper

Machine learning guided curvilinear MPC

Malavika Sharma, Bhardwaj Durvasula, Nageswara Rao, Ingo Bork, Rachit Sharma, Kushlendra Mishra, Peter Buck

Proceedings Volume 11148, 111480Q (2019) https://doi.org/10.1117/12.2538646

KEYWORDS: Photomasks, Machine learning, Optical proximity correction, Computational lithography, Data modeling, Lithography, Neural networks, Waveguides, Vestigial sideband modulation, Data processing

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Proceedings Article | 26 September 2019 Paper

Paper

Resist-slope aware modeling for mask process correction applications

Rachit Sharma, Ingo Bork, Kushlendra Mishra, ShiZhi Lyu, Linna Cong, Mingjing Tian, Malavika Sharma, Bhardwaj Durvasula, Nageswara Rao, Peter Buck

Proceedings Volume 11148, 111480G (2019) https://doi.org/10.1117/12.2536529

KEYWORDS: Process modeling, Photomasks, Etching, Critical dimension metrology, Calibration, Semiconductor manufacturing, Control systems, Model-based design, Scattering, Photoresist processing

Read Abstract +

Proceedings Article | 12 November 2018 Presentation + Paper

Presentation + Paper

Mask process correction validation for multi-beam mask lithography

Ingo Bork, Peter Buck, Christian Bürgel, Bhardwaj Durvasula, Stefan Eder-Kapl, Peter Hudek, Michal Jurkovic, Jan Klikovits, Elmar Platzgummer, Jed Rankin, Rao Nageswara, Murali Reddy, Christoph Spengler

Proceedings Volume 10810, 108100K (2018) https://doi.org/10.1117/12.2503284

KEYWORDS: Photomasks, SRAF, Calibration, Cadmium, Lithography, Double patterning technology, Data modeling, Etching, Vestigial sideband modulation, Scanning electron microscopy

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Proceedings Article | 3 October 2018 Presentation + Paper

Presentation + Paper

Advanced jog handling techniques in MPC for better QoR

Bhardwaj Durvasula, Ingo Bork, Peter Buck, Archana Rajagopalan, Nageswara Rao, Murali Reddy, Steffen Schulze

Proceedings Volume 10810, 108100M (2018) https://doi.org/10.1117/12.2503550

KEYWORDS: Optical proximity correction, Metals, Error analysis, Vestigial sideband modulation, Visualization, Data corrections, Beam shaping, Process modeling, Image quality, Computer simulations

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Proceedings Article | 3 October 2018 Presentation + Paper

Presentation + Paper

Extending mask data preparation to scale to thousands of CPUs and beyond

Archana Rajagopalan, Amanda Bowhill, Peter Buck, Bhardwaj Durvasula, Pascal Gilgenkrantz, Stephen Kim, Minyoung Park, Nageswara Rao, Steffen Schulze

Proceedings Volume 10810, 108100L (2018) https://doi.org/10.1117/12.2503551

KEYWORDS: Distributed computing, Data processing, Data storage servers, Data communications, Computing systems, Optical proximity correction

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Showing 5 of 16 publications

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