Christopher L. Borst Texas Instruments, Inc. Dallas, TX. William N. Gill Rensselaer Polytechnic Institute Troy, NY

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CHEMICAL-MECHANICAL POLISHING OF LOW DIELECTRIC CONSTANT POLYMERS AND ORGANOSILICATE GLASSES Fundamental Mechanisms and Application to 1С Interconnect Technology by Christopher L.

1 CHEMICAL-MECHANICAL POLISHING OF LOW DIELECTRIC CONSTANT POLYMERS AND ORGANOSILICATE GLASSES Fundamental Mechanisms and Application to 1С Interconnect Technology by Christopher L. Borst Texas Instruments, Inc. Dallas, TX William N. Gill Rensselaer Polytechnic Institute Troy, NY Ronald J. Gutmann Rensselaer Polytechnic Institute Troy, NY KLUWER ACADEMIC PUBLISHERS Boston / Dordrecht / London

TABLE OF CONTENTS Preface Acknowledgements xi xiü Chapter 1: Overview of 1С Interconnects 1 1.1 SILICON 1С BEOL TECHNOLOGY TRENDS 2 1.2 SIA ROADMAP INTERCONNECT PROJECTIONS 6 1.

2 TABLE OF CONTENTS Preface Acknowledgements xi xiü Chapter 1: Overview of 1С Interconnects SILICON 1С BEOL TECHNOLOGY TRENDS SIA ROADMAP INTERCONNECT PROJECTIONS LOW-K REQUIREMENTS AND MATERIALS Fluorinated Glasses Spin-On Glasses and Silsesquioxanes Organosilicate Glasses Polymers Fluorinated Polymers PorousMedia NEED FOR LOW-к CMP PROCESS UNDERSTANDING SUMMARY REFERENCES 14 Chapter 2: Low-к Interlevel Dielectrics FLUORINATED GLASSES SILSESQUIOXANES ORGANOSILICATE GLASSES POLYMERS 27

VI Contents 2.5 FLUORINATED HYDROCARBONS 34 2.6 NANOPOROUS SILICA FILMS 35 2.7 OTHER POROUS MATERIALS 38 2.8 REFERENCES 40 Chapter 3: Chemical-Mechanical Planarization (CMP) 45 3.

3 VI Contents 2.5 FLUORINATED HYDROCARBONS NANOPOROUS SILICA FILMS OTHER POROUS MATERIALS REFERENCES 40 Chapter 3: Chemical-Mechanical Planarization (CMP) CMP PROCESS DESCRIPTION CMP PROCESSES WITH COPPER METALLIZATION OxideCMP CopperCMP Damascene Patterning CMP Targeted Results and Challenges CMP OF LOW-K MATERIALS CMP PROCESS MODELS Contact Mechanics-Based Models Fluid Mechanics-Based Models LANGMUIR-HINSHELWOOD SURFACE KINETICS IN CMP MODELING REFERENCES 71 Chapter 4: CMP of BCB and SiLK Polymers REMOVAL RATE IN COPPER SLURRIES SURFACE ROUGHNESS SURFACE AND BULK FILM CHEMISTRY Angle-Resolved Surface Results Depth Profiling Results EFFECT OF CURE CONDITIONS ON BCB AND SILK REMOVAL Variation in Cure Conditions Effect of Cure Conditions on Removal Rate EFFECT OF CMP AND BCB AND SILK FILMHARDNESS 88

TABLE OF CONTENTS vii 4.6 COMPARISON OF BCB AND SILK CMP WITH OTHER POLYMER CMP 91 4.7 SUMMARY 93 4.8 REFERENCES 94 Chapter 5: CMP of Organosilicate Glasses 97 5.1 EFFECT OF FILM CARBON CONTENT 97 5.

4 TABLE OF CONTENTS vii 4.6 COMPARISON OF BCB AND SILK CMP WITH OTHER POLYMER CMP SUMMARY REFERENCES 94 Chapter 5: CMP of Organosilicate Glasses EFFECT OF FILM CARBON CONTENT Removal Rate in Oxide Slurries Removal Rate in Copper Slurries SURFACE ROUGHNESS SURFACE AND BULK FILM CHEMISTRY XPS Surface Results FTIR Bulk Profiling Results COPPER DAMASCENE PATTERNING WITH OSG DIELECTRICS Hardmasks or Dielectric Cap Layers Ill Low-к Etching CMP Integration SUMMARY REFERENCES 117 Chapter 6: Low-к CMP Model Based on Surface Kinetics ISOLATION OF THE CHEMICAL EFFECTS IN SILK CMP CMP WITH SIMPLIFIED "MODEL" SILKSLURRIES Removal Rate Dependence on Slurry Reactant Concentration KH Phthalate Slurry for Copper CMP Applications SiLK Removal Rate Dependence on Velocity PHENOMENOLOGICAL MODEL FOR CMP REMOVAL Applicability to the CMP of BCB and SiLK Applicability to the CMP of Organosilicate Glasses 133

Vlll 6.4 FIVE STEP REMOVAL MODEL USING MODIFIED LANGMUIR-HINSHELWOOD KINETICS FOR SILK CMP 134 6.4.1 Five Step Surface Mechanism 135 6.4.2 Implementation into 3-D Fluid Mechanics and Mass Transport Models 139 6.

5 Vlll 6.4 FIVE STEP REMOVAL MODEL USING MODIFIED LANGMUIR-HINSHELWOOD KINETICS FOR SILK CMP Five Step Surface Mechanism Implementation into 3-D Fluid Mechanics and Mass Transport Models Results TWO STEP REMOVAL MODEL USING HETEROGENEOUS CATALYSIS FOR SILK CMP Two Step Surface Mechanism Results EXTENDIBILITY OF MODEL TO DESCRIBE THE CMP OF OTHER MATERIALS Copper Dielectrics REFERENCES 158 Chapter 7: Copper CMP Model Based Upon Fluid Mechanics And Surface Kinetics FLOWMODEL COPPER REMOVAL MODEL Mass Transport of Oxidizer to the Wafer Surface Kinetic Surface Steps Copper Removal Rate and Effectiveness Factor Kinetic Rate Parameters Solution Procedure MODELRESULTS COPPER CMP EXPERIMENTS WITH POTASSIUM DICHROMATE BASED SLURRY SUMMARY REFERENCES 179 Chapter 8: Future Directions in 1С Interconnects and Related LOW-K ILD Planarization Issues PLANARIZATION OF INTERCONNECTS WITH ULTRA LOW-K ILDS 182

TABLE OF CONTENTS ix 8.1.1 Alternatives to Conventional CMP 182 8.1.2 Non-CMP Approaches to Planarization 183 8.2 ALTERNATIVES FOR THE POST-COPPER/ULTRA LOW-K INTERCONNECT ERA 185 8.2.1 Alternative Materials 185 8.

6 TABLE OF CONTENTS ix Alternatives to Conventional CMP Non-CMP Approaches to Planarization ALTERNATIVES FOR THE POST-COPPER/ULTRA LOW-K INTERCONNECT ERA Alternative Materials Alternative Distribution for Signals and Clocks Non-electrical Distribution of Signals and Clocks Non-Planar Integrated Assemblies - Three Dimensional (3D) Integration D WAFER-SCALE INTEGRATION USING DIELECTRIC BONDING GLUES AND INTER-WAFER INTERCONNECTION WITH COPPER DAMASCENE PATTERNING WaferBonding Inter-wafer Interconnect Comparison with Other Wafer-Scale 3D Integration Technologies SUMMARY AND CONCLUSIONS REFERENCES 200 APPENDICES Appendix A: EXPERIMENTAL PROCEDURES AND TECHNIQUES 203 Appendix B: XPS DEPTH-PROFILE DATA 221 Appendix C: CMP DATA FOR ANOMALOUS SILK REMOVAL BEHAVIOR 225 Index 227

Effect of Pump Induced Particle Agglomeration On CMP of Ultra Low k Dielectrics

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