Semiconductor Material and Device Characterization, 3rd Edition

Preface to Third Edition xiii

1 Resistivity 1

1.1 Introduction, 1

1.2 Two-Point Versus Four-Point Probe, 2

1.2.1 Correction Factors, 8

1.2.2 Resistivity of Arbitrarily Shaped Samples, 14

1.2.3 Measurement Circuits, 18

1.2.4 Measurement Errors and Precautions, 18

1.3 Wafer Mapping, 21

1.3.1 Double Implant, 21

1.3.2 Modulated Photoreflectance, 23

1.3.3 Carrier Illumination (CI), 24

1.3.4 Optical Densitometry, 25

1.4 Resistivity Profiling, 25

1.4.1 Differential Hall Effect (DHE), 26

1.4.2 Spreading Resistance Profiling (SRP), 29

1.5 Contactless Methods, 34

1.5.1 Eddy Current, 34

1.6 Conductivity Type, 38

1.7 Strengths and Weaknesses, 40

Appendix 1.1 Resistivity as a Function of Doping Density, 41

Appendix 1.2 Intrinsic Carrier Density, 43

References, 44

Problems, 50

Review Questions, 59

2 Carrier and Doping Density 61

2.1 Introduction, 61

2.2 Capacitance-Voltage (C-V), 61

2.2.1 Differential Capacitance, 61

2.2.2 Band Offsets, 68

2.2.3 Maximum-Minimum MOS-C Capacitance, 71

2.2.4 Integral Capacitance, 75

2.2.5 Mercury Probe Contacts, 76

2.2.6 Electrochemical C–V Profiler (ECV), 77

2.3 Current-Voltage (I-V), 79

2.3.1 MOSFET Substrate Voltage—Gate Voltage, 79

2.3.2 MOSFET Threshold Voltage, 81

2.3.3 Spreading Resistance, 82

2.4 Measurement Errors and Precautions, 82

2.4.1 Debye Length and Voltage Breakdown, 82

2.4.2 Series Resistance, 83

2.4.3 Minority Carriers and Interface Traps, 89

2.4.4 Diode Edge and Stray Capacitance, 90

2.4.5 Excess Leakage Current, 91

2.4.6 Deep Level Dopants/Traps, 91

2.4.7 Semi-Insulating Substrates, 93

2.4.8 Instrumental Limitations, 94

2.5 Hall Effect, 94

2.6 Optical Techniques, 97

2.6.1 Plasma Resonance, 97

2.6.2 Free Carrier Absorption, 98

2.6.3 Infrared Spectroscopy, 99

2.6.4 Photoluminescence (PL), 101

2.7 Secondary Ion Mass Spectrometry (SIMS), 102

2.8 Rutherford Backscattering (RBS), 103

2.9 Lateral Profiling, 104

2.10 Strengths and Weaknesses, 105

Appendix 2.1 Parallel or Series Connection?, 107

Appendix 2.2 Circuit Conversion, 108

References, 109

Problems, 117

Review Questions, 124

3 Contact Resistance and Schottky Barriers 127

3.1 Introduction, 127

3.2 Metal-Semiconductor Contacts, 128

3.3 Contact Resistance, 131

3.4 Measurement Techniques, 135

3.4.1 Two-Contact Two-Terminal Method, 135

3.4.2 Multiple-Contact Two-Terminal Methods, 138

3.4.3 Four-Terminal Contact Resistance Method, 149

3.4.4 Six-Terminal Contact Resistance Method, 156

3.4.5 Non-Planar Contacts, 156

3.5 Schottky Barrier Height, 157

3.5.1 Current-Voltage, 158

3.5.2 Current—Temperature, 160

3.5.3 Capacitance-Voltage, 161

3.5.4 Photocurrent, 162

3.5.5 Ballistic Electron Emission Microscopy (BEEM), 163

3.6 Comparison of Methods, 163

3.7 Strengths and Weaknesses, 164

Appendix 3.1 Effect of Parasitic Resistance, 165

Appendix 3.2 Alloys for Contacts to Semiconductors, 167

References, 168

Problems, 174

Review Questions, 184

4 Series Resistance, Channel Length and Width, and Threshold Voltage 185

4.1 Introduction, 185

4.2 PN Junction Diodes, 185

4.2.1 Current-Voltage, 185

4.2.2 Open-Circuit Voltage Decay (OCVD), 188

4.2.3 Capacitance-Voltage (C–V ), 190

4.3 Schottky Barrier Diodes, 190

4.3.1 Series Resistance, 190

4.4 Solar Cells, 192

4.4.1 Series Resistance—Multiple Light Intensities, 195

4.4.2 Series Resistance—Constant Light Intensity, 196

4.4.3 Shunt Resistance, 197

4.5 Bipolar Junction Transistors, 198

4.5.1 Emitter Resistance, 200

4.5.2 Collector Resistance, 202

4.5.3 Base Resistance, 202

4.6 MOSFETS, 206

4.6.1 Series Resistance and Channel Length–Current-Voltage, 206

4.6.2 Channel Length—Capacitance-Voltage, 216

4.6.3 Channel Width, 218

4.7 MESFETS and MODFETS, 219

4.8 Threshold Voltage, 222

4.8.1 Linear Extrapolation, 223

4.8.2 Constant Drain Current, 225

4.8.3 Sub-threshold Drain Current, 226

4.8.4 Transconductance, 227

4.8.5 Transconductance Derivative, 228

4.8.6 Drain Current Ratio, 228

4.9 Pseudo MOSFET, 230

4.10 Strengths and Weaknesses, 231

Appendix 4.1 Schottky Diode Current-Voltage Equation, 231

References, 232

Problems, 238

Review Questions, 250

5 Defects 251

5.1 Introduction, 251

5.2 Generation-Recombination Statistics, 253

5.2.1 A Pictorial View, 253

5.2.2 A Mathematical Description, 255

5.3 Capacitance Measurements, 258

5.3.1 Steady-State Measurements, 259

5.3.2 Transient Measurements, 259

5.4 Current Measurements, 267

5.5 Charge Measurements, 269

5.6 Deep-Level Transient Spectroscopy (DLTS), 270

5.6.1 Conventional DLTS, 270

5.6.2 Interface Trapped Charge DLTS, 280

5.6.3 Optical and Scanning DLTS, 283

5.6.4 Precautions, 285

5.7 Thermally Stimulated Capacitance and Current, 288

5.8 Positron Annihilation Spectroscopy (PAS), 289

5.9 Strengths and Weaknesses, 292

Appendix 5.1 Activation Energy and Capture Cross-Section, 293

Appendix 5.2 Time Constant Extraction, 294

Appendix 5.3 Si and GaAs Data, 296

References, 301

Problems, 308

Review Questions, 316

6 Oxide and Interface Trapped Charges, Oxide Thickness 319

6.1 Introduction, 319

6.2 Fixed, Oxide Trapped, and Mobile Oxide Charge, 321

6.2.1 Capacitance-Voltage Curves, 321

6.2.2 Flatband Voltage, 327

6.2.3 Capacitance Measurements, 331

6.2.4 Fixed Charge, 334

6.2.5 Gate-Semiconductor Work Function Difference, 335

6.2.6 Oxide Trapped Charge, 338

6.2.7 Mobile Charge, 338

6.3 Interface Trapped Charge, 342

6.3.1 Low Frequency (Quasi-static) Methods, 342

6.3.2 Conductance, 347

6.3.3 High Frequency Methods, 350

6.3.4 Charge Pumping, 352

6.3.5 MOSFET Sub-threshold Current, 359

6.3.6 DC-IV, 361

6.3.7 Other Methods, 363

CONTENTS ix

6.4 Oxide Thickness, 364

6.4.1 Capacitance-Voltage, 364

6.4.2 Current-Voltage, 369

6.4.3 Other Methods, 369

6.5 Strengths and Weaknesses, 369

Appendix 6.1 Capacitance Measurement Techniques, 371

Appendix 6.2 Effect of Chuck Capacitance and Leakage Current, 372

References, 374

Problems, 381

Review Questions, 387

7 Carrier Lifetimes 389

7.1 Introduction, 389

7.2 Recombination Lifetime/Surface Recombination Velocity, 390

7.3 Generation Lifetime/Surface Generation Velocity, 394

7.4 Recombination Lifetime—Optical Measurements, 395

7.4.1 Photoconductance Decay (PCD), 399

7.4.2 Quasi-Steady-State Photoconductance (QSSPC), 402

7.4.3 Short-Circuit Current/Open-Circuit Voltage Decay (SCCD/OCVD), 402

7.4.4 Photoluminescence Decay (PLD), 404

7.4.5 Surface Photovoltage (SPV), 404

7.4.6 Steady-State Short-Circuit Current (SSSCC), 411

7.4.7 Free Carrier Absorption, 413

7.4.8 Electron Beam Induced Current (EBIC), 416

7.5 Recombination Lifetime—Electrical Measurements, 417

7.5.1 Diode Current-Voltage, 417

7.5.2 Reverse Recovery (RR), 420

7.5.3 Open-Circuit Voltage Decay (OCVD), 422

7.5.4 Pulsed MOS Capacitor, 424

7.5.5 Other Techniques, 428

7.6 Generation Lifetime—Electrical Measurements, 429

7.6.1 Gate-Controlled Diode, 429

7.6.2 Pulsed MOS Capacitor, 432

7.7 Strengths and Weaknesses, 440

Appendix 7.1 Optical Excitation, 441

Appendix 7.2 Electrical Excitation, 448

References, 448

Problems, 458

Review Questions, 464

8 Mobility 465

8.1 Introduction, 465

8.2 Conductivity Mobility, 465

8.3 Hall Effect and Mobility, 466

8.3.1 Basic Equations for Uniform Layers or Wafers, 466

8.3.2 Non-uniform Layers, 471

8.3.3 Multi Layers, 474

8.3.4 Sample Shapes and Measurement Circuits, 475

8.4 Magnetoresistance Mobility, 479

8.5 Time-of-Flight Drift Mobility, 482

8.6 MOSFET Mobility, 489

8.6.1 Effective Mobility, 489

8.6.2 Field-Effect Mobility, 500

8.6.3 Saturation Mobility, 502

8.7 Contactless Mobility, 502

8.8 Strengths and Weaknesses, 502

Appendix 8.1 Semiconductor Bulk Mobilities, 503

Appendix 8.2 Semiconductor Surface Mobilities, 506

Appendix 8.3 Effect of Channel Frequency Response, 506

Appendix 8.4 Effect of Interface Trapped Charge, 507

References, 508

Problems, 514

Review Questions, 521

9 Charge-based and Probe Characterization 523

9.1 Introduction, 523

9.2 Background, 524

9.3 Surface Charging, 525

9.4 The Kelvin Probe, 526

9.5 Applications, 533

9.5.1 Surface Photovoltage (SPV), 533

9.5.2 Carrier Lifetimes, 534

9.5.3 Surface Modification, 537

9.5.4 Near-Surface Doping Density, 538

9.5.5 Oxide Charge, 538

9.5.6 Oxide Thickness and Interface Trap Density, 540

9.5.7 Oxide Leakage Current, 541

9.6 Scanning Probe Microscopy (SPM), 542

9.6.1 Scanning Tunneling Microscopy (STM), 543

9.6.2 Atomic Force Microscopy (AFM), 544

9.6.3 Scanning Capacitance Microscopy (SCM), 547

9.6.4 Scanning Kelvin Probe Microscopy (SKPM), 550

9.6.5 Scanning Spreading Resistance Microscopy (SSRM), 553

9.6.6 Ballistic Electron Emission Microscopy (BEEM), 554

9.7 Strengths and Weaknesses, 556

References, 556

Problems, 560

Review Questions, 561

10 Optical Characterization 563

10.1 Introduction, 563

10.2 Optical Microscopy, 564

10.2.1 Resolution, Magnification, Contrast, 565

10.2.2 Dark-Field, Phase, and Interference Contrast Microscopy, 568

10.2.3 Confocal Optical Microscopy, 570

10.2.4 Interferometric Microscopy, 572

10.2.5 Defect Etches, 575

10.2.6 Near-Field Optical Microscopy (NFOM), 575

10.3 Ellipsometry, 579

10.3.1 Theory, 579

10.3.2 Null Ellipsometry, 581

10.3.3 Rotating Analyzer Ellipsometry, 582

10.3.4 Spectroscopic Ellipsometry (SE), 583

10.3.5 Applications, 584

10.4 Transmission, 585

10.4.1 Theory, 585

10.4.2 Instrumentation, 587

10.4.3 Applications, 590

10.5 Reflection, 592

10.5.1 Theory, 592

10.5.2 Applications, 594

10.5.3 Internal Reflection Infrared Spectroscopy, 598

10.6 Light Scattering, 599

10.7 Modulation Spectroscopy, 600

10.8 Line Width, 601

10.8.1 Optical-Physical Methods, 601

10.8.2 Electrical Methods, 603

10.9 Photoluminescence (PL), 604

10.10 Raman Spectroscopy, 608

10.11 Strengths and Weaknesses, 610

Appendix 10.1 Transmission Equations, 611

Appendix 10.2 Absorption Coefficients and Refractive Indices for Selected

Semiconductors, 613

References, 615

Problems, 621

Review Questions, 626

11 Chemical and Physical Characterization 627

11.1 Introduction, 627

11.2 Electron Beam Techniques, 628

11.2.1 Scanning Electron Microscopy (SEM), 629

11.2.2 Auger Electron Spectroscopy (AES), 634

11.2.3 Electron Microprobe (EMP), 639

11.2.4 Transmission Electron Microscopy (TEM), 645

11.2.5 Electron Beam Induced Current (EBIC), 649

11.2.6 Cathodoluminescence (CL), 651

11.2.7 Low-Energy, High-Energy Electron Diffraction (LEED), 652

11.3 Ion Beam Techniques, 653

11.3.1 Secondary Ion Mass Spectrometry (SIMS), 654

11.3.2 Rutherford Backscattering Spectrometry (RBS), 659

11.4 X-Ray and Gamma-Ray Techniques, 665

11.4.1 X-Ray Fluorescence (XRF), 666

11.4.2 X-Ray Photoelectron Spectroscopy (XPS), 668

11.4.3 X-Ray Topography (XRT), 671

11.4.4 Neutron Activation Analysis (NAA), 674

11.5 Strengths and Weaknesses, 676

Appendix 11.1 Selected Features of Some Analytical Techniques, 678

References, 678

Problems, 686

Review Questions, 687

12 Reliability and Failure Analysis 689

12.1 Introduction, 689

12.2 Failure Times and Acceleration Factors, 690

12.2.1 Failure Times, 690

12.2.2 Acceleration Factors, 690

12.3 Distribution Functions, 692

12.4 Reliability Concerns, 695

12.4.1 Electromigration (EM), 695

12.4.2 Hot Carriers, 701

12.4.3 Gate Oxide Integrity (GOI), 704

12.4.4 Negative Bias Temperature Instability (NBTI), 711

12.4.5 Stress Induced Leakage Current (SILC), 712

12.4.6 Electrostatic Discharge (ESD), 712

12.5 Failure Analysis Characterization Techniques, 713

12.5.1 Quiescent Drain Current (IDDQ), 713

12.5.2 Mechanical Probes, 715

12.5.3 Emission Microscopy (EMMI), 715

12.5.4 Fluorescent Microthermography (FMT), 718

12.5.5 Infrared Thermography (IRT), 718

12.5.6 Voltage Contrast, 718

12.5.7 Laser Voltage Probe (LVP), 719

12.5.8 Liquid Crystals (LC), 720

12.5.9 Optical Beam Induced Resistance Change (OBIRCH), 721

12.5.10 Focused Ion Beam (FIB), 723

12.5.11 Noise, 723

12.6 Strengths and Weaknesses, 726

Appendix 12.1 Gate Currents, 728

References, 730

Problems, 737

Review Questions, 740

Appendix 1 List of Symbols 741

Appendix 2 Abbreviations and Acronyms 749

Index 755