Handbook of Wafer Bonding

The focus behind this book on wafer bonding is the fast paced changes in the research and development in three-dimensional (3D) integration, temporary bonding and micro-electro-mechanical systems (MEMS) with new functional layers. Written by authors and edited by a team from microsystems companies and industry-near research organizations, this handbook and reference presents dependable, first-hand information on bonding technologies.

Part I sorts the wafer bonding technologies into four categories: Adhesive and Anodic Bonding; Direct Wafer Bonding; Metal Bonding; and Hybrid Metal/Dielectric Bonding. Part II summarizes the key wafer bonding applications developed recently, that is, 3D integration, MEMS, and temporary bonding, to give readers a taste of the significant applications of wafer bonding technologies.

This book is aimed at materials scientists, semiconductor physicists, the semiconductor industry, IT engineers, electrical engineers, and libraries.

Auteur
Dr. Peter Ramm is head of the department Device and 3D Integration of Fraunhofer EMFT in Munich, Germany, where he is responsible for process integration of innovative devices and heterogeneous systems with a specific focus on 3D integration technologies. Dr. Ramm received the physics and Dr. rer. nat. degrees from the University of Regensburg and subsequently worked for Siemens in the DRAM facility where he was responsible for the process integration. In 1988 he joined Fraunhofer IFT in Munich, focusing for over two decades on 3D integration technologies. Peter Ramm is author or co-author of over 100 publications and 24 patents. He received the "Ashman Award 2009" from the International Electronics Packaging Society (IMAPS) "For Pioneering Work on 3D IC Stacking and Integration, and leading-edge work on SiGe and Si technologies". Peter Ramm is Fellow and Life Member of IMAPS, organizing committee member of IEEE 3DIC conference and co-editor of Wiley's "Handbook of 3D Integration".

Dr. James Jian-Qiang Lu received his Dr. rer. nat. (Ph.D.) degree from Technical University of Munich, and is currently an Associate Professor in Electrical Engineering at Rensselaer Polytechnic Institute (RPI), Troy, NY. Dr. Lu has worked on 3D hyper-integration technology, design and
applications for over a decade, with focus on hyper-integration and micro-nano-bio interfaces for future chips. He has more than 200 publications in the areas from micro-nano-electronics theory and design to materials, processing, devices, integration and packaging. He is an IEEE Fellow for contributions to three-dimensional integrated circuit technology, and a Fellow and Life Member of International Microelectronics and Packaging Society (IMAPS). He is a recipient of the 2008 IEEE CPMT Exceptional Technical Achievement Award for his pioneering contributions to and leadership in 3D integration/packaging and the 2010 IMAPS William D. Ashman Achievement Award for contributions and research in 3D integration and packaging.

Dr. Maaike M.V. Taklo is employed as a senior research scientist at SINTEF ICT in Norway at the Department of Instrumentation which she joined in 2010. She is group leader for "Advanced Packaging and Interconnects" within this department. From 1998 until 2010 she was employed at the Department of Microsystems and Nanotechnology within SINTEF ICT where she worked on MEMS processing and was responsible for their wafer level bonding activities. She received her Ph.D. degree in Physical Electronics from the University of Oslo for her thesis entitled "Wafer bonding for MEMS". She is the author or co-author of over 35 papers. In 2008 she received a "Best of Conference" award at the Pan Pacific Symposium for her presentation of "BCB Bonded Wireless Vibration Sensor". She is member of the technical committee of IWLPC and the program committee of 3DIC.

Contenu

Preface xv

Obituary xvii

List of Contributors xxi

Introduction xxv

Part One Technologies 1

A. Adhesive and Anodic Bonding 3

1 Glass Frit Wafer Bonding 3 Roy Knechtel

1.1 Principle of Glass Frit Bonding 3

1.2 Glass Frit Materials 4

1.3 Screen Printing: Process for Bringing Glass Frit Material onto Wafers 5

1.4 Thermal Conditioning: Process for Transforming Printed Paste into Glass for Bonding 8

1.5 Wafer Bond Process: Essential Wafer-to-Wafer Mounting by a Glass Frit Interlayer 11

1.6 Characterization of Glass Frit Bonds 14

1.7 Applications of Glass Frit Wafer Bonding 15

1.8 Conclusions 16

References 17

2 Wafer Bonding Using Spin-On Glass as Bonding Material 19 Viorel Dragoi

2.1 Spin-On Glass Materials 19

2.2 Wafer Bonding with SOG Layers 21

2.2.1 Experimental 21

2.2.2 Wafer Bonding with Silicate SOG Layers 22

2.2.3 Wafer Bonding with Planarization SOG 28

2.2.4 Applications of Adhesive Wafer Bonding with SOG Layers 29

2.2.5 Conclusion 30

References 31

3 Polymer Adhesive Wafer Bonding 33 Frank Niklaus and Jian-Qiang Lu

3.1 Introduction 33

3.2 Polymer Adhesives 34

3.2.1 Polymer Adhesion Mechanisms 34

3.2.2 Properties of Polymer Adhesives 36

3.2.3 Polymer Adhesives for Wafer Bonding 38

3.3 Polymer Adhesive Wafer Bonding Technology 42

3.3.1 Polymer Adhesive Wafer Bonding Process 43

3.3.2 Localized Polymer Adhesive Wafer Bonding 50

3.4 Wafer-to-Wafer Alignment in Polymer Adhesive Wafer Bonding 52

3.5 Examples for Polymer Adhesive Wafer Bonding Processes and Programs 54

3.5.1 Bonding with Thermosetting Polymers for Permanent Wafer Bonds (BCB) or for Temporary Wafer Bonds (mr-I 9000) 54

3.5.2 Bonding with Thermoplastic Polymer (HD-3007) for Temporary and Permanent Wafer Bonds 56

3.6 Summary and Conclusions 57

References 58

4 Anodic Bonding 63 Adriana Cozma Lapadatu and Kari Schjølberg-Henriksen

4.1 Introduction 63

4.2 Mechanism of Anodic Bonding 64

4.2.1 Glass Polarization 64

4.2.2 Achieving Intimate Contact 65

4.2.3 Interface Reactions 66

4.3 Bonding Current 67

4.4 Glasses for Anodic Bonding 68

4.5 Characterization of Bond Quality 69

4.6 Pressure Inside Vacuum-Sealed Cavities 70

4.7 Effect of Anodic Bonding on Flexible Structures 71

4.8 Electrical Degradation of Devices during Anodic Bonding 71

4.8.1 Degradation by Sodium Contamination 72

4.8.2 Degradation by High Electric Fields 73

4.9 Bonding with Thin Films 75

4.10 Conclusions 76

References 77

B. Direct Wafer Bonding 81

5 Direct Wafer Bonding 81 Manfred Reiche and Ulrich Gösele

5.1 Introduction 81

5.2 Surface Chemistry and Physics 82

5.3 Wafer Bonding Techniques 84

5.3.1 Hydrophilic Wafer Bonding 84

5.3.2 Hydrophobic Wafer Bonding 86

5.3.3 Low-Temperature Wafer Bonding 88

5.3.4 Wafer Bonding in Ultrahigh Vacuum 89

5.4 Properties of Bonded Interfaces 90

5.5 Applications of Wafer Bonding 93

5.5.1 Advanced Substrates for Microelectronics 93

5.5.2 MEMS and Nanoelectromechanical Systems 95

5.6 Conclusions 95

References 96

6 Plasma-Activated Bonding 101 Maik Wiemer, Dirk Wuensch, Joerg Braeuer, and Thomas Gessner

6.1 Introduction 101

6.2 Theory 102

6.2.1 (Silicon) Direct Bonding 102

6.2.2 Mechanisms of Plasma on Silicon Surfaces 103

6.2.3 Physical Definition of a Plasma 104

6.3 Classification of PAB 104

6.3.1 Low-Pressure PAB 105

6.3.2 Atmospheric-Pressure PAB 106

6.4 Procedure of PAB 107

6.4.1 Process Flow 107

6.4.2 Characterization Techniques 108

6.4.3 Experiments and Results 110

6.5 Applications for PAB 111

6.5.1 Pressure Sensor 112

6.5.2 Optical Microsystem 112

6.5.3 Microfluidics Packaging 113

6.5.4 Backside-Illuminated CMOS Image Sensor 113

6.5.5 CMOS Compatibility of Low-Pressure PAB 114

6.6 Conclusion 115

References 115

C. Metal Bonding 119

7 Au/Sn Solder 119 Hermann Oppermann and Matthias Hutter

7.1 Introduction 119

7.2 Au/Sn Solder Alloy 120

7.3 Reflow Soldering 127

7.4 The…