Fundamental Principles of Optical Lithography

The Science of Microfabrication

AvChris Mack

Inbunden, Engelska, 2007

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Beskrivning

The fabrication of an integrated circuit requires a variety of physical and chemical processes to be performed on a semiconductor substrate. In general, these processes fall into three categories: film deposition, patterning, and semiconductor doping. Films of both conductors and insulators are used to connect and isolate transistors and their components. By creating structures of these various components millions of transistors can be built and wired together to form the complex circuitry of modern microelectronic devices. Fundamental to all of these processes is lithography, ie, the formation of three-dimensional relief images on the substrate for subsequent transfer of the pattern to the substrate.This book presents a complete theoretical and practical treatment of the topic of lithography for both students and researchers. It comprises ten detailed chapters plus three appendices with problems provided at the end of each chapter.Additional Information:Visiting http://www.lithoguru.com/textbook/index.html enhances the reader's understanding as the website supplies information on how you can download a free laboratory manual, Optical Lithography Modelling with MATLAB®, to accompany the textbook. You can also contact the author and find help for instructors.

Produktinformation

Utgivningsdatum:2007-11-16
Mått:175 x 253 x 36 mm
Vikt:1 162 g
Format:Inbunden
Språk:Engelska
Antal sidor:544
Förlag:John Wiley & Sons Inc
ISBN:9780470018934

Utforska kategorier

Maskinteknik och material inom Naturvetenskap och teknik

Mer om författaren

Dr. Chris A. Mack developed the lithography simulation software PROLITH, and founded and ran the company FINLE Technologies fro ten years. He then served as Vice President of Lithography Technology for KLA-Tencor for five years, until 2005. In 2003 he received the SEMI Award for North America for his efforts in lithography simulation and education. He is also an adjunct faculty member at the University of Texas at Austin. Currently, he writes, teaches, and consults on the field of semiconductor microlithography in Austin, Texas.

Innehållsförteckning

Preface xv1. Introduction to Semiconductor Lithography 11.1 Basics of IC Fabrication 21.1.1 Patterning 21.1.2 Etching 31.1.3 Ion Implantation 51.1.4 Process Integration 61.2 Moore’s Law and the Semiconductor Industry 71.3 Lithography Processing 121.3.1 Substrate Preparation 141.3.2 Photoresist Coating 151.3.3 Post-Apply Bake 181.3.4 Alignment and Exposure 191.3.5 Post-exposure Bake 231.3.6 Development 241.3.7 Postbake 251.3.8 Measure and Inspect 251.3.9 Pattern Transfer 251.3.10 Strip 26Problems 262. Aerial Image Formation – The Basics 292.1 Mathematical Description of Light 292.1.1 Maxwell’s Equations and the Wave Equation 302.1.2 General Harmonic Fields and the Plane Wave in a Nonabsorbing Medium 322.1.3 Phasors and Wave Propagation in an Absorbing Medium 332.1.4 Intensity and the Poynting Vector 362.1.5 Intensity and Absorbed Electromagnetic Energy 372.2 Basic Imaging Theory 382.2.1 Diffraction 392.2.2 Fourier Transform Pairs 432.2.3 Imaging Lens 452.2.4 Forming an Image 472.2.5 Imaging Example: Dense Array of Lines and Spaces 482.2.6 Imaging Example: Isolated Space 502.2.7 The Point Spread Function 512.2.8 Reduction Imaging 532.3 Partial Coherence 562.3.1 Oblique Illumination 572.3.2 Partially Coherent Illumination 582.3.3 Hopkins Approach to Partial Coherence 622.3.4 Sum of Coherent Sources Approach 632.3.5 Off-Axis Illumination 652.3.6 Imaging Example: Dense Array of Lines and Spaces Under Annular Illumination 662.3.7 Köhler Illumination 662.3.8 Incoherent Illumination 692.4 Some Imaging Examples 70Problems 713. Aerial Image Formation – The Details 753.1 Aberrations 753.1.1 The Causes of Aberrations 753.1.2 Describing Aberrations: the Zernike Polynomial 783.1.3 Aberration Example – Tilt 813.1.4 Aberration Example – Defocus, Spherical and Astigmatism 833.1.5 Aberration Example – Coma 843.1.6 Chromatic Aberrations 853.1.7 Strehl Ratio 903.2 Pupil Filters and Lens Apodization 903.3 Flare 913.3.1 Measuring Flare 923.3.2 Modeling Flare 943.4 Defocus 953.4.1 Defocus as an Aberration 953.4.2 Defocus Example: Dense Lines and Spaces and Three-Beam Imaging 983.4.3 Defocus Example: Dense Lines and Spaces and Two-Beam Imaging 1003.4.4 Image Isofocal Point 1023.4.5 Focus Averaging 1033.4.6 Reticle Defocus 1043.4.7 Rayleigh Depth of Focus 1053.5 Imaging with Scanners Versus Steppers 1063.6 Vector Nature of Light 1083.6.1 Describing Polarization 1113.6.2 Polarization Example: TE Versus TM Image of Lines and Spaces 1133.6.3 Polarization Example: The Vector PSF 1143.6.4 Polarization Aberrations and the Jones Pupil 1143.7 Immersion Lithography 1173.7.1 The Optical Invariant and Hyper-NA Lithography 1183.7.2 Immersion Lithography and the Depth of Focus 1203.8 Image Quality 1213.8.1 Image cd 1213.8.2 Image Placement Error (Distortion) 1233.8.3 Normalized Image Log-Slope (NILS) 1233.8.4 Focus Dependence of Image Quality 125Problems 1264. Imaging in Resist: Standing Waves and Swing Curves 1294.1 Standing Waves 1304.1.1 The Nature of Standing Waves 1304.1.2 Standing Waves for Normally Incident Light in a Single Film 1314.1.3 Standing Waves in a Multiple-Layer Film Stack 1354.1.4 Oblique Incidence and the Vector Nature of Light 1374.1.5 Broadband Illumination 1414.2 Swing Curves 1444.2.1 Reflectivity Swing Curve 1444.2.2 Dose-to-Clear and CD Swing Curves 1484.2.3 Swing Curves for Partially Coherent Illumination 1494.2.4 Swing Ratio 1514.2.5 Effective Absorption 1544.3 Bottom Antireflection Coatings 1564.3.1 BARC on an Absorbing Substrate 1574.3.2 BARCs at High Numerical Apertures 1604.3.3 BARC on a Transparent Substrate 1644.3.4 BARC Performance 1654.4 Top Antireflection Coatings 1674.5 Contrast Enhancement Layer 1704.6 Impact of the Phase of the Substrate Reflectance 1704.7 Imaging in Resist 1734.7.1 Image in Resist Contrast 1734.7.2 Calculating the Image in Resist 1774.7.3 Resist-Induced Spherical Aberrations 1794.7.4 Standing Wave Amplitude Ratio 1814.8 Defining Intensity 1834.8.1 Intensity at Oblique Incidence 1834.8.2 Refraction into an Absorbing Material 1844.8.3 Intensity and Absorbed Energy 187Problems 1885. Conventional Resists: Exposure and Bake Chemistry 1915.1 Exposure 1915.1.1 Absorption 1915.1.2 Exposure Kinetics 1945.2 Post-Apply Bake 1995.2.1 Sensitizer Decomposition 2005.2.2 Solvent Diffusion and Evaporation 2055.2.3 Solvent Effects in Lithography 2095.3 Post-exposure Bake Diffusion 2105.4 Detailed Bake Temperature Behavior 2145.5 Measuring the ABC Parameters 217Problems 2196. Chemically Amplified Resists: Exposure and Bake Chemistry 2236.1 Exposure Reaction 2236.2 Chemical Amplification 2246.2.1 Amplification Reaction 2256.2.2 Diffusion 2276.2.3 Acid Loss 2306.2.4 Base Quencher 2326.2.5 Reaction–Diffusion Systems 2336.3 Measuring Chemically Amplified Resist Parameters 2356.4 Stochastic Modeling of Resist Chemistry 2376.4.1 Photon Shot Noise 2376.4.2 Chemical Concentration 2396.4.3 Some Mathematics of Binary Random Variables 2416.4.4 Photon Absorption and Exposure 2426.4.5 Acid Diffusion, Conventional Resist 2466.4.6 Acid-Catalyzed Reaction–Diffusion 2476.4.7 Reaction–Diffusion and Polymer Deblocking 2516.4.8 Acid–Base Quenching 253Problems 2547. Photoresist Development 2577.1 Kinetics of Development 2577.1.1 A Simple Kinetic Development Model 2587.1.2 Other Development Models 2617.1.3 Molecular Weight Distributions and the Critical Ionization Model 2647.1.4 Surface Inhibition 2657.1.5 Extension to Negative Resists 2677.1.6 Developer Temperature 2677.1.7 Developer Normality 2687.2 The Development Contrast 2707.2.1 Defining Photoresist Contrast 2707.2.2 Comparing Definitions of Contrast 2747.2.3 The Practical Contrast 2767.2.4 Relationship between g and r max /r min 2777.3 The Development Path 2787.3.1 The Euler–Lagrange Equation 2797.3.2 The Case of No z-Dependence 2807.3.3 The Case of a Separable Development Rate Function 2827.3.4 Resist Sidewall Angle 2837.3.5 The Case of Constant Development Gradients 2847.3.6 Segmented Development and the Lumped Parameter Model (LPM) 2867.3.7 LPM Example – Gaussian Image 2877.4 Measuring Development Rates 292Problems 2938. Lithographic Control in Semiconductor Manufacturing 2978.1 Defining Lithographic Quality 2978.2 Critical Dimension Control 2998.2.1 Impact of CD Control 2998.2.2 Improving CD Control 3038.2.3 Sources of Focus and Dose Errors 3058.2.4 Defining Critical Dimension 3078.3 How to Characterize Critical Dimension Variations 3098.3.1 Spatial Variations 3098.3.2 Temporal Variations and Random Variations 3118.3.3 Characterizing and Separating Sources of CD Variations 3128.4 Overlay Control 3148.4.1 Measuring and Expressing Overlay 3158.4.2 Analysis and Modeling of Overlay Data 3178.4.3 Improving Overlay Data Analysis 3208.4.4 Using Overlay Data 3238.4.5 Overlay Versus Pattern Placement Error 3268.5 The Process Window 3268.5.1 The Focus–Exposure Matrix 3268.5.2 Defining the Process Window and DOF 3328.5.3 The Isofocal Point 3368.5.4 Overlapping Process Windows 3388.5.5 Dose and Focus Control 3398.6 H–V Bias 3438.6.1 Astigmatism and H–V Bias 3438.6.2 Source Shape Asymmetry 3458.7 Mask Error Enhancement Factor (MEEF) 3488.7.1 Linearity 3488.7.2 Defining MEEF 3498.7.3 Aerial Image MEEF 3508.7.4 Contact Hole MEEF 3528.7.5 Mask Errors as Effective Dose Errors 3538.7.6 Resist Impact on MEEF 3558.8 Line-End Shortening 3568.8.1 Measuring LES 3578.8.2 Characterizing LES Process Effects 3598.9 Critical Shape and Edge Placement Errors 3618.10 Pattern Collapse 362Problems 3669. Gradient-Based Lithographic Optimization: Using the Normalized Image Log-Slope 3699.1 Lithography as Information Transfer 3699.2 Aerial Image 3709.3 Image in Resist 3779.4 Exposure 3789.5 Post-exposure Bake 3819.5.1 Diffusion in Conventional Resists 3819.5.2 Chemically Amplified Resists – Reaction Only 3839.5.3 Chemically Amplified Resists – Reaction–Diffusion 3849.5.4 Chemically Amplified Resists – Reaction–Diffusion with Quencher 3919.6 Develop 3939.6.1 Conventional Resist 3979.6.2 Chemically Amplified Resist 3999.7 Resist Profile Formation 4009.7.1 The Case of a Separable Development Rate Function 4009.7.2 Lumped Parameter Model 4019.8 Line Edge Roughness 4049.9 Summary 406Problems 40810. Resolution Enhancement Technologies 41110.1 Resolution 41210.1.1 Defining Resolution 41310.1.2 Pitch Resolution 41610.1.3 Natural Resolutions 41810.1.4 Improving Resolution 41810.2 Optical Proximity Correction (OPC) 41910.2.1 Proximity Effects 41910.2.2 Proximity Correction – Rule Based 42210.2.3 Proximity Correction – Model Based 42510.2.4 Subresolution Assist Features (SRAFs) 42710.3 Off-Axis Illumination (OAI) 42910.4 Phase-Shifting Masks (PSM) 43410.4.1 Alternating PSM 43510.4.2 Phase Conflicts 43810.4.3 Phase and Intensity Imbalance 43910.4.4 Attenuated PSM 44110.4.5 Impact of Phase Errors 44510.5 Natural Resolutions 45010.5.1 Contact Holes and the Point Spread Function 45010.5.2 The Coherent Line Spread Function (LSF) 45210.5.3 The Isolated Phase Edge 453Problems 454Appendix A. Glossary of Microlithographic Terms 457Appendix B. Curl, Divergence, Gradient, Laplacian 491Appendix C. The Dirac Delta Function 495Index 501