Computational Lithography

Summary

A Unified Summary of the Models and Optimization Methods Used in Computational LithographyOptical lithography is one of the most challenging areas of current integrated circuit manufacturing technology. The semiconductor industry is relying more on resolution enhancement techniques (RETs), since their implementation does not require significant changes in fabrication infrastructure. Computational Lithography is the first book to address the computational optimization of RETs in optical lithography, providing an in-depth discussion of optimal optical proximity correction (OPC), phase shifting mask (PSM), and off-axis illumination (OAI) RET tools that use model-based mathematical optimization approaches.The book starts with an introduction to optical lithography systems, electric magnetic field principles, and the fundamentals of optimization from a mathematical point of view. It goes on to describe in detail different types of optimization algorithms to implement RETs. Most of the algorithms developed are based on the application of the OPC, PSM, and OAI approaches and their combinations. Algorithms for coherent illumination as well as partially coherent illumination systems are described, and numerous simulations are offered to illustrate the effectiveness of the algorithms. In addition, mathematical derivations of all optimization frameworks are presented.The accompanying MATLABr software files for all the RET methods described in the book make it easy for readers to run and investigate the codes in order to understand and apply the optimization algorithms, as well as to design a set of optimal lithography masks. The codes may also be used by readers for their research and development activities in their academic or industrial organizations. An accompanying MATLABr software guide is also included. An accompanying MATLABr software guide is included, and readers can download the software to use with the guide at ftp://ftp.wiley.com/public/sci_tech_med/computational_lithography.Tailored for both entry-level and experienced readers, Computational Lithography is meant for faculty, graduate students, and researchers, as well as scientists and engineers in industrial organizations whose research or career field is semiconductor IC fabrication, optical lithography, and RETs. Computational lithography draws from the rich theory of inverse problems, optics, optimization, and computational imaging; as such, the book is also directed to researchers and practitioners in these fields.

Preface
Acknowledgments
Acronyms
Introduction
Optical Lithography
Optical Lithography and Integrated Circuits
Brief History of Optical Lithography Systems
Rayleigh's Resolution
Resist Processes and Characteristics
Techniques in Computational Lithography
Optical Proximity Correction
Phase Shifting Masks
Offaxis Illumination
Second Generation RETs
Outline
Optical Lithography Systems
Partially Coherent Imaging Systems
Abbe's Model
Hopkins Diffraction Model
Coherent and Incoherent Imaging Systems
Approximation Models
Fourier Series Expansion Model
Singular Value Decomposition Model
Average Coherent Approximation Model
Discussion and Comparison
Summary
Rule-based Resolution Enhancement Techniques
RET Types
Rule-based RETs
Model-based RETs
Hybrid RETs
Rule-based OPC
Catastrophic OPC
One-dimensional OPC
Line-shortening Reduction OPC
Two-dimensional OPC
Rule-based PSM
Dark-field Application
Light-field Application
Rule-based OAI
Summary
Fundamentals of Optimization
Definition and Classification
Definitions in The Optimization Problem
Classification of Optimization Problems
Unconstrained Optimization
Solution of Unconstrained Optimization Problem
Unconstrained Optimization Algorithms
Summary
Computational Lithography with Coherent Illumination
Problem Formulation
OPC Optimization
OPC Design Algorithm
Simulations
Two-phase PSM Optimization
Two-phase PSM Design Algorithm
Simulations
Generalized PSM Optimization
Generalized PSM Design Algorithm
Simulations
Resist Modeling Effects
Summary
Regularization Framework
Discretization Penalty
Discretization Penalty for OPC Optimization
Discretization Penalty for Two-phase PSM Optimization
Discretization Penalty for Generalized PSM Optimization
Complexity Penalty
Total Variation Penalty
Global Wavelet Penalty
Localized Wavelet Penalty
Summary
Computational Lithography with Partially Coherent Illumination
OPC Optimization
OPC Design Algorithm using the Fourier Series Expansion Model
Simulations using the Fourier Series Expansion Model
OPC Design Algorithm using the Average Coherent Approximation Model
Simulations using the Average Coherent Approximation Model
Discussion and Comparison
PSM Optimization
PSM Design Algorithm using the Singular Value Decomposition Model
Discretization Regularization for PSM Design Algorithm
Simulations
Summary
Other RET Optimization Techniques
Double Patterning Method
Post-Processing based on 2D DCT
Photoresist Tone Reversing Method
Summary
Source and Mask Optimization
Lithography Preliminaries
Topological Constraint
Source Mask Optimization Algorithm
Simulations
Summary
Coherent Thickmask Optimization
Kirchhoff Boundary Conditions
Boundary Layer Model
Boundary Layer Model in Coherent Imaging Systems
Boundary Layer Model in Partially Coherent Imaging Systems
Lithography Preliminaries
OPC Optimization
Topological Constraint
OPC Optimization Algorithm based on BL Model under Coherent Illumination
Simulations
PSM Optimization
Topological Constraint
PSM Optimization Algorithm based on BL Model under Coherent Illumination
Simulations
Summary
Conclusions and New Directions of Computational Lithography
Conclusion
New Directions of Computational Lithography
Formula derivation in Chapter 5
Manhattan geometry
Formula derivation in Chapter 6
Formula derivation in Chapter 7
Formula derivation in Chapter 8
Formula derivation in Chapter 9
Formula derivation in Chapter 10
Software Guide
References
Index
Table of Contents provided by Publisher. All Rights Reserved.

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