1. Photon Beam Damage and Charging at Solid Surfaces John H. Thomas III

1. Photon Beam Damage and Charging at Solid Surfaces John H. Thomas III 1. Introduction............................. 2. Electrostatic Charging of Samples in Photoemission Experiments............................ 2.1. Electrostatic Surface Charging...... 2.2. Differential Surface Charging................ 2.3. Lateral and In-Depth Charge Effects... 2.4. Small-Spot Analysis Charging Effects... 3. Energy Scale Calibration... 4. The Auger Parameter: Charge-Independent Chemical Identification........................... 5. Photon Damage... 5.1. Photon Absorption Processes... 5.2. Radiation Damage to Inorganic Materials... 5.3. Photon Damage to Polymers................ 6. Closing Comments... References............................... 1 2 2 8 10 13 13 18 20 20 25 29 34 35 2. Electron Beam Damage at Solid Surfaces Carlo G. Pantano, Andrew S. D Souza and Alan M. Then 1. Introduction............................. 2. Fundamentals... 2.1. Electronic Excitation Processes................ 2.1.1. Electron-Stimulated Desorption.... 2.1.2. Electron-Stimulated Adsorption........... 2.1.3. Decomposition of Surface Layers and Thin Films....................... xiii 39 41 41 41 45 49

xiv Contents 2.1.4. Oxidation of Surface Layers and Thin Films... 2.1.5. Thresholds for Sample Damage Resulting from Electronic Excitation..... 2.2. Charging Insulators... 2.3. Electromigration in Insulators... 2.4. Electron-Beam-Induced Heating... 3. Electron Beam Effects in Auger Surface Analyses..... 3.1. Physical Effects... 3.2. Contaminated, Oxidized, or Coated Surfaces... 3.3. Polymers... 3.4. Glasses... 3.5. Sputter Depth Profiles... 3.6. Microanalyses...... 4. Recommendations... 5. References... 5.1. Review of Beam Damage in Electron Microscopy... 5.2. General Discussions of Electron Beam Damage in Surface Analysis... 5.3. Fundamentals of Electron-Stimulated Desorption..... 5.4. Studies of Electron Beam Interactions at Solid Surfaces... 5.5. Charging of Insulators Resulting from Electron Beam Irradiation... 5.6. Electron Beam Damage in Glasses... 5.7. Electron Beam Damage during Surface Analysis... 53 54 58 60 64 65 65 69 74 74 80 83 85 88 92 93 94 3. Ion Beam Bombardment Effects on Solid Surfaces at Energies Used for Sputter Depth Profiling L. S. Dake, D. E. King, J. R. Pitts, and A. W. Czanderna 1. Introduction... 1.1. Overview... 1.2. Ion Beams and Solids: Topics Not Covered... 1.3. Definitions and Nomenclature... 1.4. Overview of Ion Surface and Ion Solid Interactions... 2. IonBeam Solid Interactions.... 2.1. Introduction...... 2.2. Ion Beam... 2.2.1. Reflection/Backscattering............. 2.2.2. Penetration and Trapping... 2.3. Ion Substrate Interactions...... 97 97 102 103 105 108 108 110 110 111 116

xv 2.4. Mixing and Implantation of Material... 2.4.1. Ballistic Mixing... 2.4.2. Diffusional Mixing Processes.... 2.5. Removal of Material..................... 2.5.1. Physical Sputtering.... 2.5.2. Sputter Yields... 2.5.3. Differential Sputtering... 2.6. Altered Layer (Zone of Mixing)... 3. Structural Changes Resulting from Ion Beam Bombardment.... 3.1. Bond Stretching, Bond Breaking, and Surface Reconstruction from Ion Beam Bombardment.... 3.2. Structural Changes as Nanotopography from Ion Beam Bombardment... 3.3. Surface Defect Formation from Ion Beam Bombardment... 3.4. Damage Depth and Defect Density from Ion Beam Bombardment... 3.5. Enhanced Diffusion and Changes in Electrical Properties from Ion Beam Bombardment... 4. Physical Effects: Ion-Beam-Induced Topography.... 4.1. Introduction... 4.2. Mechanisms for Topography Development..... 4.3. Microscopic and Macroscopic Roughness.... 4.4. Etch Pits... 4.5. Pyramids... 4.6. Cones... 4.7. Whiskers... 4.8. Ripples and Corrugation... 4.9. Sputter-Induced Recrystallization... 4.10. Coalescence to Form Islands... 4.11. Swelling... 4.12. Smoothing... 4.13. Miscellaneous Results...... 4.13.1. Topographical Differences in the Same Sample... 4.13.2. Topography of Kapton and Teflon after Atom Beam Bombardment... 4.13.3. Sputtering with Non-Noble-Gas Ions.... 4.13.4. Annealing Sputter Damage... 4.14. Concluding Remarks... 5. Compositional Changes and Chemical Effects...... 5.1. Introduction... 118 118 122 123 124 125 131 133 139 140 143 149 154 163 168 168 169 173 176 181 182 189 189 193 193 194 194 197 197 198 198

xvi Contents 5.2. Organic Materials... 5.3. Alloys... 5.3.1. Ternary Alloys... 5.4. Semiconductors... 5.5. Metal Oxides... 5.5.1. Simple Metal Oxides.... 5.5.2. Complex Oxides: Perovskites... 5.5.3. Complex Oxides: Glasses...... 5.6. Compounds... 5.7. Calculations and Simulations... 6. Depth Resolution: Sample, Beam, and Instrumental Effects... 6.1. Introduction... 6.2. Nature and Condition of the Sample... 6.3. Ion Beam Bombardment Effects... 6.4. Instrumental Effects... 6.5. Ultimate and Practical Limits on... 7. Combined Beam Effects... 8. Applications... 9. Summary and Concluding Remarks... References... Appendix 1. Acronyms and Abbreviations... 203 206 210 211 213 213 217 218 221 226 227 227 227 231 239 247 249 251 252 255 273 4. Characterization of Surface Topography T. V. Vorburger, J. A. Dagata, G. Wilkening, and K. Iizuka 1. Introduction... 2. Results Obtainable with Profiling Instruments........... 2.1. Profile Recordings and Dimensional Measurement... 2.2. Surface Statistics... 2.2.1. Surface Parameters... 2.2.2. Statistical Functions... 2.2.3. Other Statistical Descriptors... 2.3. Bandwidth Limits... 3. Stylus Instruments... 3.1. Height Resolution and Range... 3.2. Lateral Resolution and Range... 3.3. Stylus Load and Surface Deformation... 3.4. Other Distortions..... 3.5. Calibration... 275 279 279 281 282 285 290 290 291 291 293 296 297 299

xvii 3.6. Applications... 3.7. Area Profiling with Stylus Instruments.... 4. Optical Profiling Techniques...... 5. Scanned Probe Microscopy... 5.1. Short History of Scanned Probe Microscopy.... 5.2. Calibration and Characterization... 5.2.1. Instruments for Displacement Calibration... 5.2.2. Calibration Specimens for Displacement... 5.2.3. Instruments for Critical Dimensions and High Resolution................... 5.2.4. Specimens for Critical Dimensions... 5.3. Other Types of Scanned Probe Microscopes..... 5.3.1. Force-Based Methods (Mechanical).... 5.3.2. Methods Based on Other Probe-Sample Interactions... 5.4. Applications of SPM Measurements... 5.4.1. Data Storage Industries...... 5.4.2. Microelectronics Industries.... 5.4.3. Polymers and Coatings Industries... 5.4.4. Optical Element Industries..... 5.4.5. Mechanical Parts Industries and Materials Science... 5.4.6. Electrochemical Science... 5.5. Future Directions: Techniques and Instrumentation... 6. Intercomparisons......... 7. Conclusions... References... 300 300 302 307 307 311 311 314 315 318 319 321 323 325 325 326 327 327 328 329 330 334 339 341 5. Depth Profiling Using Sputtering Methods H. W. Werner and P. R. Boudewijn 1. Introduction... 1.1. Principle of Sputter Depth Profiling... 1.2. Methods for Sputter Depth Profiling... 1.3. Different Modes of Sputter Depth Profiling... 1.3.1. Planar Sputter Depth Profiling... 1.3.2. Crater-Wall, Tapered-Section, or Angular-Mapping Depth Profiling... 1.4. Comparison of Sputter Depth Profiling with Other Methods... 1.4.1. Consumptive Methods for Depth Profiling... 355 357 359 360 360 362 362 362

xviii Contents 1.4.2. Nonconsumptive Methods and Modes for Depth Profiling...... 2. Physical Basis of the Sputtering Process... 2.1. Introduction... 2.2. Theory of the Sputtering Process...... 2.2.1. Binary Collision Theory.............. 2.2.2. Classification of Sputtering Events... 2.2.3. Sputtering from Linear Collision Cascades... 2.3. Sputtering Yields (Experimental).............. 2.4. Information Depth... 2.5. Processes Related to Sputtering... 3. Experimental Aspects...... 3.1. Introduction.... 3.2. Ion Beam Sources..... 3.3. Time Needed to Obtain a Depth Profile.... 4. Analysis of Sputter Depth Profiles... 4.1. Introduction..... 4.2. Conversion of the Sputter Depth Profile of an Element X, I(X, t), into a Concentration Depth Profile c(z)... 4.2.1. Determination of the Depth Scale... 4.2.2. Conversion of the Measured Signal I into an Elemental Concentration c... 4.3. Artifacts in Sputter Depth Profiles... 4.3.1. Artifacts Related to the Interaction Process between Energetic Projectiles and the Solid... 4.3.2. Artifacts Related to the Properties of the Sample. 4.3.3. Artifacts Related to Instrumental Parameters... 4.4. Evaluation of a Measured Depth Profile.... 4.4.1. Depth Resolution... 4.4.2. Detection Limit for a Given Element... 5. Application of Sputter Depth Profiling to Various Thin-Film Materials... 5.1. Stable Isotope Tracers... 5.2. Thin-Film Interdiffusion and Multilayer Analysis.... 5.3. Corrosion and Oxidation...... 5.4. Catalysts... 5.5. Polymer Metal Interfaces.... 5.6. Insulating Materials... 5.7. Semiconductor Materials..... 5.8. Miscellaneous Applications..... 5.9. Newcomers to Sputter-Depth-Profiling Techniques... 363 367 367 371 373 376 378 378 378 381 383 386 386 389 391 394 394 396 397 397 398 398 402 402 403 405 409 411

xix 6. Summary and Future Prospects.... 412 Acknowledgment... 412 References... 412 Index... 421