Dr. Christophe Pierrat
Director at IC Images Technologies Inc
SPIE Involvement:
Author | Instructor
Publications (33)

Proc. SPIE. 7973, Optical Microlithography XXIV
KEYWORDS: Lithography, Data modeling, Scattering, Etching, Electrons, Photomasks, Mask making, Neodymium, Data corrections, Model-based design

Proc. SPIE. 7973, Optical Microlithography XXIV
KEYWORDS: Wafer-level optics, Lithography, Optical lithography, Data modeling, Polarization, Calibration, Photomasks, Optical proximity correction, Semiconducting wafers, Phase shifts

PROCEEDINGS ARTICLE | September 29, 2010
Proc. SPIE. 7823, Photomask Technology 2010
KEYWORDS: Data modeling, Backscatter, Scattering, Ions, Photomasks, Acquisition tracking and pointing, Convolution, Neodymium, Model-based design, Process modeling

PROCEEDINGS ARTICLE | September 25, 2010
Proc. SPIE. 7823, Photomask Technology 2010
KEYWORDS: Wafer-level optics, Diffraction, Refractive index, Data modeling, Polarization, Calibration, Computer simulations, Photomasks, Semiconducting wafers, Phase shifts

PROCEEDINGS ARTICLE | September 25, 2010
Proc. SPIE. 7823, Photomask Technology 2010
KEYWORDS: Lithography, Scanning electron microscopy, Printing, Photomasks, Beam shaping, Optical proximity correction, SRAF, Line edge roughness, Semiconducting wafers, Vestigial sideband modulation

Proc. SPIE. 7748, Photomask and Next-Generation Lithography Mask Technology XVII
KEYWORDS: Reticles, Data modeling, Manufacturing, Scanning electron microscopy, Photomasks, Computer aided design, Semiconducting wafers, Tolerancing, CAD systems, Vestigial sideband modulation

Showing 5 of 33 publications
Course Instructor
SC723: The Limits of Optical Lithography
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.
SC244: Low k<sub>1</sub> Lithography
This course explains why resolution enhancement technologies are required for low k<sub>1</sub> lithography and how they can be implemented in a practical manner. Real layouts are used as examples. The infrastructure needed to implement some of these techniques in production is also reviewed from a system integration standpoint. A complete flow including data, photo-mask, and wafer processing is described.
SC117: The Fundamental Limits of Optical Lithography
This course covers the capabilities and challenges in optical lithography using practical approaches to understand basic scientific and engineering principles. Using fundamental concepts, practical examples, and optical demonstrations, the limits of optical lithography are defined and explored. As optical lithography is pushed beyond classical limits, an understanding of imaging from a dimensional description (of the mask and wafer) as well as a spatial frequency perspective (of the optics) becomes necessary. This course will develop the connection between the two to describe fundamental optical limits and relationships. The consequences of variations in NA, changing coherence (sigma), implementing optical enhancements (including phase shift masking, off-axis illumination, and optical proximity correction), and the influence of aberrations will be presented iusing an intuitive approach. The goal is to develop a fundamental and intuitive understanding of topics related to diffraction by a photomask, collection by an optical system, and imaging into a photoresist. Fourier spectral analysis, coherency theory, lens interaction, aberration concepts, and image enhancement are describe in fairly simple terms and several optical demonstrations help develop the concepts. This course is the first of a two-part sequence but both parts don't need to be taken.
SC724: Optical Lithography Extension: New Resolution Enhancement Techniques and Design for Manufacturing
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.
SC124: Pushing the Limits: Hyper-NA, Immersion, Polarization, and Pitch Division (Double Patterning) in Optical Lithography
This stand-alone course covers the extension of optical microlithography concepts that can follow the "The Fundamental Limits of Optical Lithography" course, SC117. Topics covered relate to current and future hyper-NA imaging that allows for applicaion into sub-45nm device generations. With the advent of immersion lithography, improvements in resolution and focal depth are made possible. The potential of this technology will be covered, along with the implications of large angle imaging and polarization (both benefits and detriments) along with methods to control large angle effects. This course extends on fundamental concepts of optical lithography by expanding the spatial frequency description of imaging and allowing for an intuitive understanding of the technologies involved. A more complete description of optical imaging processes is also pursued with discussions of feature and pitch specific illumination, optical proximity correction (high and low order), phase-masking, and aberration compensation. Finally, concepts of pitch division (i.e. double patterning) will be explored to understand the practical limits of optical lithography, possibly to 22 nm device generations. Attendees will learn how far we can go, what is tolerable, and what must be sacrificed to push optical lithography as far as possible. Several optical demonstrations will help to develop an intuitive sense of the concepts.
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