Advanced MEMS Packaging

Transcription

1 Advanced MEMS Packaging John H. Lau Chengkuo Lee C. S. Premachandran Yu Aibin Ш New York Chicago San Francisco Lisbon London Madrid Mexico City Milan New Delhi San Juan Seoul Singapore Sydney Toronto

2 Contents Foreword Preface Acknowledgments xv xvii xxi 1 Introduction to MEMS Introduction Commercial Applications of MEMS MEMS Markets Top 30 MEMS Suppliers Introduction to MEMS Packaging MEMS Packaging Patents since U.S. MEMS Packaging Patents Japanese MEMS Packaging Patents Worldwide MEMS Packaging Patents 27 References 43 2 Advanced MEMS Packaging Introduction Advanced 1С Packaging Moore's Law versus More Than Moore (MTM) D 1С Integration with WLP Low-Cost Solder Microbumps for 3D 1С SiP Thermal Management of 3D 1С SiP with TSV Advanced MEMS Packaging D MEMS WLP: Designs and Materials D MEMS WLP: Processes 72 References 76 3 Enabling Technologies for Advanced MEMS Packaging Introduction TSVs for MEMS Packaging Via Formation Dielectric Isolation Layer (SiO z ) Deposition 86 vii

3 viü Contents Barrier/Adhesion and Seed Metal Layer Deposition Via Filling Cu Polishing by Chemical/ Mechanical Polish (CMP) Fabrication of an ASIC Wafer with TSVs Fabrication of Cap Wafer with TSVs and Cavity Piezoresistive Stress Sensors for MEMS Packaging Design and Fabrication of Piezoresistive Stress Sensors Calibration of Stress Sensors Stresses in Wafers after Mounting on a Dicing Tape Stresses in Wafers after Thinning (Back-Grinding) Wafer Thinning and Thin-Wafer Handling M Wafer Support System EVG's Temporary Bonding and Debonding System A Simple Support-Wafer Method for Thin-Wafer Handling Low-Temperature Bonding for MEMS Packaging Ill How Does Low-Temperature Bonding with Solders Work? Low-Temperature C2C Bonding Low-Temperature C2W Bonding Low-Temperature W2W Bonding MEMS Wafer Dicing Fundamentals of SD Technology Dicing of SOI Wafers Dicing of Silicon-on-Silicon Wafers Dicing of Silicon-on-Glass Wafers RoHS-Compliant MEMS Packaging EURoHS What Is the Definition of X-Free (e.g., Pb-Free)? What Is a Homogeneous Material? What Is the TAC? How Is a Law Published in the EU RoHS Directive? 135

4 Contents jx EU RoHS Exemptions Current Status of RoHS Compliance in the Electronics Industry Lead-Free Solder-Joint Reliability of MEMS Packages 138 References 149 Advanced MEMS Wafer-Level Packaging Introduction Micromachining, Wafer-Bonding Technologies, and Interconnects Thin-Film Technologies Bulk Micromachining Technologies Conventional Wafer-Bonding Technologies for Packaging Plasma-Assisted Wafer-Bonding Technologies Electrical Interconnects Solder-Based Intermediate-Layer Bonding Wafer-Level Encapsulation High-Temperature Encapsulation Process Low-Temperature Encapsulation Process Wafer-Level Chip Capping and MCM Technologies Wafer-Level MEMS Packaging Based on Low-Temperature Solders: Case Study Case Study: In/Ag System of Noneutectic Composition Case Study: Eutectic InSn Solder for Cu-Based Metallization Summary and Future Outlook 202 References 203 Optical MEMS Packaging: Communications Introduction Actuation Mechanisms and Integrated Micromachining Processes Electrostatic Actuation Thermal Actuation Magnetic Actuation 219

5 X Contents Piezoelectric Actuation Integrated Micromachining Processes Optical Switches Small-Scale Optical Switches Large-Scale Optical Switches Variable Optical Attenuators Early Development Work Surface-Micromachined VOAs DRIE-Derived Planar VOAs Using Electrostatic Actuators DRIE-Derived Planar VOAs Using Electrothermal (Thermal) Actuators D VOAs VOAs Using Various Mechanisms Packaging, Testing, and Reliability Issues Manufacturability and Self-Assembly Case Study: VOAs Case Study: Optical Switches Summary and Future Outlook 285 References Optical MEMS Packaging: Bubble Switch Introduction D Packaging Boundary-Value Problem Geometry Materials Boundary Conditions Nonlinear Analyses of the 3D Photonic Switch Creep Hysteresis Loops Deflections Shear-Stress Time-History Shear-Creep-Strain Time-History Creep-Strain Energy-Density Range Isothermal Fatigue Tests and Results Sample Preparation Test Setup and Procedures Test Results Thermal Fatigue Life Prediction of the Sealing Ring 314

6 Contents xi 6.7 Appendix A: Package Deflection by Twyman-Green Interferometry Method Sample Preparation Test Setup and Procedure Temperature Conditions Measurement Results Appendix B: Package Deflection by Finite-Element Method Appendix C: Finite-Element Modeling of the Bolt Description of the Bolted Model Responses of the Bolted Photonic Switch 322 References 325 Optical MEMS: Microbolometer Packaging Introduction Bolometer Chip Thermal Optimization Final Temperature Stability Testing Structural Optimization of the Package Vacuum Packaging of Bolometer Ge Window Getter Attachment and Activation Outgassing Study in a Vacuum Package Testing Setup for Bolometer Package Testing Image Testing 350 References 352 Bio-MEMS Packaging Introduction Bio-MEMS Chip Microfluidic Components Microfluidic Cartridge Biocompatible Polymeric Materials Microfluidic Packaging Polymer Microfabrication Techniques Replication Technologies Overview of Existing DNA and RNA Extractor Biocartridges Fabrication of PDMS Layers Assembly of PDMS Microfluidic Packages

7 XÜ Contents Microfluidic Package without Reservoirs Development of Reservoir and Valve Self-Contained Microfluidic Cartridge Microfluidic Package with Self-Contained Reservoirs Pin-Valve Design Fluid Flow-Control Mechanism Fabrication Substrate Fabrication Material Selection for the Reservoir Membrane Permeability of Material Thermocompression Bonding Bonding of PMMA to PMMA for the Channel Layer Polypropylene to PMMA for Reservoir and Channel Layer Tensile Test Microfluidic Package Testing Fluid Testing Biologic Testing on a Biosample Sample Preparation and Setup Pretreatment of the Cartridge PCR Amplification 394 References Biosensor Packaging Introduction Review of Optical Coherence Tomography (OCT) Biosensor Packaging Micromirror Single-Mode Optical Fiber and GRIN Lens Upper Substrate Lower Substrate The Package Configuration of the Probe Optical Properties and Theories Evaluations of Parameters Optical Simulation Optical Model of the Probe Effect of Mirror Curvature on Coupling Efficiency 415

8 Contents Effect of Lateral Tilt of a Flat Micromirror on a Curved Sample Effect of Vertical Tilt of a Flat Micromirror on a Curved Sample Effect of Vertical Tilt of a Flat Micromirror on a Flat Sample Assembly of the Optical Probe Fabrication of SiOB Probe Assembly Probe Housing Testing of the Probe Optical Alignment Axial Scanning Test Result Probe Imaging Optical Efficiency Testing 431 References 433 Accelerometer Packaging Introduction Wafer-Level Package Requirements Electrical Modeling Package Structure Extraction Methodology of the Interconnection Characteristics Wafer-Level Packaging Process Method 1: TSV with Sacrificial Wafer Method 2: TSV without Sacrificial Wafer Method 3: TSV with MEMS Wafer Wafer Separation Process Process Integration Sacrificial Wafer Removal Wafer-Level Vacuum Sealing Vacuum Measurement Using a MEMS Motion Analyzer Reliability Testing: Vacuum Maintenance Wafer-Level 3D Package for an Accelerometer 471 References 473 Radiofrequency MEMS Switches Introduction Design of RF MEMS Switches Design of Capacitive Switches 475

9 ents Design of Metal-Contact Switches Mechanical Design of RF MEMS Switches Fabrication of RF MEMS Switches Surface Micromachining of RF MEMS Switches Bulk Micromachining of RF MEMS Switches Characterization of RF MEMS Switches RF Performance Mechanical Performance Reliability of RF MEMS Switches Reliability of Capacitive Switches Reliability of Metal-Contact Switches Summary 492 References 493 RF MEMS Tunable Capacitors and Tunable Band-Pass Filters Introduction RF MEMS Tunable Capacitors Analog Tuning of RF MEMS Capacitors Digital Tuning of RF MEMS Capacitors RF MEMS Tunable Band-Pass Filters Analog Tuning of a MEMS Band-Pass Filter Digital Tuning of an RF MEMS Filter Summary 512 References 513 Advanced Packaging of RF MEMS Devices Introduction Zero-Level Packaging Chip Capping Thin-Film Capping One-Level Packaging ReHability of Packaged RF MEMS Devices Summary 528 References 528 Index 531