John Petersen is a Scientific Director, Advanced Patterning and co-lead of the AttoLab at imec, Leuven, Belgium and the 2018 Adams State University Outstanding Alumnus. He has extensive experience in all aspects of lithography and strong modeling background. John has been heavily involved in the advanced design and manufacturing of photomasks for extremely high-resolution optical lithography. He has experience from Texas Instruments, Shipley Company, SEMATECH, Petersen Advanced Lithography, Inc., RenderStream, and Periodic Structures, Inc. John is co-developer of the 2006 SEMI Innovation Award-winning Maxwell equation solver EMF3. He has been involved with the development of commercial interferometric lithography hardware; work that began with his direct involvement with Steve Brueck at the UNM as a technical advisory board member of the Nanolithography MURI. John is a Fellow of SPIE and an appointed Adjunct Professor of Physical Chemistry at the University of Maryland. He has published 90 papers, 45 of which he was the primary author. He taught advanced optical lithography for many years and holds 12 patents. He is known worldwide for describing the chemical physics of chemically amplified resists (Byers-Petersen Reaction-Diffusion Equations) and for his work in advanced optical lithography. His current research is developing super-resolution methods, hardware and materials for nanolithography and nanoscopy, the determination of the reaction mechanism kinetics of EUV exposed photoresists, and the development of high NA EUV imaging techniques.
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PSCAR utilizes an area-selective photosensitization mechanism to generate more acid in the exposed areas during a UV exposure. PSCAR is an attempt to break the resolution, line-edge-roughness, and sensitivity trade-off (RLS trade-off) relationships that limit standard chemically amplified resists. The photosensitizer, which is generated in exposed area by a photoacid catalytic reaction, absorbs the UV exposure light selectively and generates additional acid in the exposed area only.
Material development and UV exposure uniformity are the key elements of PSCAR technology for semiconductor mass fabrication. This paper will review the approaches toward improvement of PSCAR resist process robustness. The chemistry’s EUV exposure cycle of learning results from experiments at imec will be discussed.
Moore’s Law has been changing the world for over 50 years, and advances in lithography have been a (the) major factor in its success. The success of lithography scaling, however, may cause the undoing of Moore’s Law as smaller features become susceptible to stochastics variations such as linewidth roughness, local critical dimension uniformity, and stochastic defects. This course will look at how stochastic variation during lithography affects semiconductor devices, how to measure stochastic variations, the major causes of stochastic variation, and what stochastics will mean for the future of lithography scaling.
1. Introduction to Line-Edge Roughness (LER) and Linewidth Roughness (LWR): LER Experimental Results, Device Effects, LER Trends
2. Metrology for LER/LWR: Power Spectral Density Measurement, Low-frequency roughness and feature-to-feature variation, High-frequency roughness and within variation, Measuring roughness using SEM images, Simulating rough features
3. Stochastic Modeling Fundamentals – No Longer a Continuum: Discrete Random Variables, Binary Distribution, Poisson Distribution, Example – Chemical Concentration
4. A Stochastic Model of Lithography: Optical Imaging – Photon Shot Noise, Photon Absorption and Exposure, EUV Resist Exposure, Diffusion – A Random Walk, Reaction-Diffusion, Acid-Base Quenching, Development, The LER Model, Efficacy of LER post-process smoothing
5. Future Work
This course delves into the profound impacts of advances in lithography on the evolution of Moore’s Law over five decades. It critically examines how the success of lithography scaling could paradoxically contribute to the potential disruption of Moore’s Law due to emerging susceptibilities to stochastic variations such as linewidth roughness and local critical dimension uniformity. We will discuss the following topics on stochastic variations:
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1. Introduction to Line-Edge Roughness (LER) and Linewidth Roughness (LWR): LER Experimental Results, Device Effects, LER Trends.
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2. Metrology for LER/LWR: Power Spectral Density Measurement, Low-frequency roughness and feature-to-feature variation, High-frequency roughness and within variation, Measuring roughness using SEM images, Simulating rough features.
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3. Stochastic Lithography Modeling: Beyond Continuum: Discrete Random Variables, Binary Distribution, Poisson Distribution, Example: Chemical Concentration.
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4. Development and use of a Stochastic Model of Lithography: Optical Imaging: Photon Shot Noise, EUV Resist Exposure and Photon Absorption, Diffusion Processes: A Random Walk, Reaction-Diffusion and Acid-Base Quenching, Development and Efficacy of LER post-process smoothing, The Comprehensive LER Model.
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5. Future Directions in Stochastic Lithography Research: Exploring advancements and innovations in mitigating stochastic variations, Evaluating potential trajectories for the future of lithography scaling in relation to Moore’s Law.
Moore’s Law has been changing the world for over 50 years, and advances in lithography have been a (the) major factor in its success. This course will review several major conceptual and technical underpinnings of lithography for semiconductor manufacturing, providing a large, holistic view of where we are, how we got here, and where we are going next. Topics include Moore’s Law, resolution and depth of focus, the components of optical resolution, chemically amplified resists, lithography impacts on design, and next generation lithography.
1. Moore’s Law – History, components, meaning, Dennard scaling, impact on lithography
2. The focus-exposure matrix, depth of focus, and the Normalized Image Log-Slope (NILS)
3. Chemically amplified resists, acid and quencher diffusion, and isofocal bias
4. Imaging, resolution, and the change from three-beam to two-beam imaging
5. Design – WYSIWYG, design rules, litho-friendly design
6. The Future – what will be the next generation of lithography? How will it impact Moore’s Law?
The microlithography process is critical to the successful manufacture of integrated circuits. Control of the critical dimension (CD) of the device is paramount to producing devices that meet design specification.
Eight critical process categories that control feature size are considered. This course looks at each category and discusses the impact that parameter variation has on the lithography process, on device yield and on final device performance. Emphasis is placed on the chemical and physical relationships within the lithography process.This course will consider lithography methods and process tuning appropriate for production lithography now that production is moving below historical limits.This is an excellent opportunity to get advice and specific direction on resist processing.
Over the past decade, optical lithography has remained at the forefront of the patterning of ICs in spite of the ever decreasing feature sizes required. Incremental improvements of the optical systems in combination with the use of resolution enhancement techniques (RET) have made this transition possible. The implementation of some of these techniques has lead to major infrastructure adjustments and changes covering a wide spectrum of fields including the EDA industry, the photo-mask industry, and the semiconductor equipment industry.
This course will explain the fundamental limits of optical lithography from a theoretical standpoint including the description of partially coherent imaging as well as polarization and aberration effects on the imaging quality. Commonly used resolution enhancement techniques such as off-axis illumination, phase-shifting mask, and proximity effect correction will be explained and their practical implementation will be reviewed. This course is the first part of a two part sequence but each part can be taken separately.
Optical lithography has been extended through the use of resolution enhancement techniques (RET) like off-axis illumination, phase-shifting mask, and proximity effect correction. As these techniques reach their limits, their practical implementation becomes more dubious and requires a careful consideration of their use at the design phase in order to achieve sufficient yields.
Recently the field of design for manufacturing (DFM) has enjoyed a large success in part because of the poor ramp-up of the latest technology nodes due to limited process latitude at low k1.
At the same time, the industry is looking for new ways to improve the resolution and the process latitude on the wafer by using new resolution enhancement techniques going beyond the established techniques such as off-axis illumination, phase-shifting mask, and proximity effect correction. These new techniques include the combined optimization of the exposure source and of the mask design as well as the use of multiple exposures or multiple patterning steps.
This course will describe the most relevant design for manufacturing techniques and their practical implementation. The fundamentals of the new resolution enhancement techniques will also be explained and their implementation will be discussed. This course is the second part of a two part sequence but each part can be taken separately.
This course discusses ways to extend optical lithography using proper selection of masks, mask design, optical proximity correction, exposure tool, illuminator, and resist design for image process integration. This integration is to make each component of the imaging system work with the other components to produce focus-exposure process windows large enough to use in a manufacturing environment. The course provides the basics for doing optical extension, shows how to design an integrated imaging system and finishes by providing a method for assessing factory capabilities to do optical extensions in production.
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