Microelectromechanical systems

About: Microelectromechanical systems is a research topic. Over the lifetime, 10255 publications have been published within this topic receiving 151342 citations. The topic is also known as: MEMS & microelectromechanical system.

Ferroelectric thin films for micro-sensors and actuators: a review

Abstract: This paper reviews deposition, integration, and device fabrication of ferroelectric PbZrxTi1-xO3 (PZT) films for applications in microelectromechanical systems. As examples, a piezoelectric ultrasonic micromotor and pyroelectric infrared detector array are presented. A summary of the published data on the piezoelectric properties of PZT thin films is given. The figures of merit for various applications are discussed. Some considerations and results on operation, reliability, and depolarization of PZT thin films are presented.

M-TEST: A test chip for MEMS material property measurement using electrostatically actuated test structures

Abstract: A set of electrostatically actuated microelectromechanical test structures is presented that meets the emerging need for microelectromechanical systems (MEMS) process monitoring and material property measurement at the wafer level during both process development and manufacturing. When implemented as a test chip or drop-in pattern for MEMS processes, M-Test becomes analogous to the electrical MOSFET test structures (often called E-Test) used for extraction of MOS device parameters. The principle of M-Test is the electrostatic pull-in of three sets of test structures [cantilever beams (CB's), fixed-fixed beams (FB's), and clamped circular diaphragms (CD's)] followed by the extraction of two intermediate quantities (the S and B parameters) that depend on the product of material properties and test structure geometry. The S and B parameters give a direct measure of the process uniformity across an individual wafer and process repeatability between wafers and lots. The extraction of material properties (e.g., Young's modulus, plate modulus, and residual stress) from these S and B parameters is then accomplished using geometric metrology data. Experimental demonstration of M-Test is presented using results from MIT's dielectrically isolated wafer-bonded silicon process. This yielded silicon plate modulus results which agreed with literature values to within /spl plusmn/4%. Guidelines for adapting the method to other MEMS process technologies are presented.

The Science and Engineering of Microelectronic Fabrication

Abstract: PART I: OVERVIEW AND MATERIALS 1. An Introduction to Microelectronic Fabrication 1.1 Microelectronic Technologies -- A Simple Example 1.2 Unit Processes and Technologies 1.3 A Roadmap for the Course 1.4 Summary 2. Semiconductor Substrates 2.1 Phase Diagrams and Solid Solubility 2.2 Crystallography and Crystal Structure 2.3 Crystal Defects 2.4 Czochralski Growth 2.5 Bridgman Growth of GaAs 2.6 Float Zone Growth 2.7 Water Preparation and Specifications 2.8 Summary and Future Trends Problems References PART II: UNIT PROCESSING I: HOT PROCESSING AND ION IMPLANTATION 3. Diffusion 3.1 Fick's Diffusion Equation in One Dimension 3.2 Atomistic Models of Diffusion 3.3 Analytic Solutions of Fick's Law 3.4 Corrections to Simple Theory 3.5 Diffusion Coefficients for Common Dopants 3.6 Analysis of Diffused Profiles 3.7 Diffusion in SiO2 3.8 Diffusion Systems 3.9 SUPREM Simulations of Diffusion Profiles 3.10 Summary Problems References 4. Thermal Oxidation 4.1 The Deal-Grove Model of Oxidation 4.2 The Linear and Parabolic Rate Coeffients 4.3 The Initial Oxidation Regime 4.4 The Structure of SiO2 4.5 Oxide Characterization 4.6 The Effects of Dopants During Oxidation and Polysilicon Oxidation 4.7 Oxidation Induced Stacking Faults 4.8 Alternative Gate Insulations 4.9 Oxidation Sytems 4.10 SUPREM Oxidations 4.11 Summary Problems References 5. Ion Implantation 5.1 Idealized Ion Implantation Systems 5.2 Coulomb Scattering 5.3 Vertical Projected Range 5.4 Channeling and Lateral Projected Range 5.5 Implantation Damage 5.6 Shallow Junction Formation 5.7 Buried Dielectrics 5.8 Ion Implantation Systems -- Problems and Concerns 5.9 Implanted Profiles Using SUPREM+ 5.10 Summary Problems References 6. Rapid Thermal Processing 6.1 Gray Body Radiation, Heat Exchange, and Optical Absorption 6.2 High Density Optical Sources and Chamber Design 6.3 Temperature Measurement 6.4 Temperature Measurement 6.4 Thermoplastic Stress 6.5 Rapid Thermal Activation of Impurities 6.6 Rapid Thermal Processing of Dielectrics 6.7 Silicidation and Contact Formation 6.8 Alternative Rapid Thermal Processing Systems 6.9 Summary Problems References PART III: UNIT PROCESSES 2: PATTERN TRANSFER 7. Optical Lithography 7.1 Lithography Overview 7.2 Diffraction 7.3 The Modulation Transfer Function and Optical Exposures 7.4 Source Systems and Spatial Coherence 7.5 Contact/Proximity Printers 7.6 Projection Printers 7.7 Advanced Mask Concepts 7.8 Surface Reflections and Standing Waves 7.9 Alignment 7.10 Summary Problems References 8. Photoresists 8.1 Photoresist Types 8.2 Organic Materials and Polymers 8.3 Typical Reactions of DQN Positive Photoresist 8.4 Contrast Curves 8.5 The Critical Modulation Transfer Function 8.6 Applying and Developing Photoresist 8.7 Second Order Exposure Effects 8.8 Advanced Photoresists and Photoresist Processes 8.9 Summary Problems References 9. Nonoptical Lithographic Techniques 9.1 Interactions of High Energy Beams with Matter 9.2 Direct Write Electron Beam Lithography Systems 9.3 Direct Write Electron Beam Lithography Summary and Outlook 9.4 X-Ray Sources 9.5 Proximity X-Ray Exposure Systems 9.6 Membrane Masks 9.7 Projection X-Ray Lithography 9.8 Projection Electron Beam Lithography (SCALPEL) 9.9 E-bean and X-Ray Resists 9.10 Radiation Damage in MOS Devices 9.11 Summary Problems References PART IV: UNIT PROCESSES 3: THIN FILMS 10. Vacuum Science and Plasmas 10.1 The Kinetic Theory of Gasses 10.2 Gas Flow and Conductance 10.3 Pressure Ranges and Vacuum Pumps 10.4 Vacuum Seals and Pressure Measurement 10.5 The DC Glow Discharge 10.6 RF Discharges 10.7 High Density Plasmas 10.8 Summary Problems References 11. Etching 11.1 Wet Etching 11.2 Chemical Mechanical Publishing 11.3 Basic Regimes of Plasma Etching 11.4 High Pressure Plasma Etching 11.5 Ion Milling 11.6 Reactive Ion Etching 11.7 Damage in Reative Ion Etching 11.8 High Density Plasma (HDP) Etching 11.9 Liftoff 11.10 Summary Problems References 12. Physical Deposition: Evaporation and Sputtering 12.1 Phase Diagrams: Sublimation and Evaporation 12.2 Deposition Rates 12.3 Step Coverage 12.4 Evaporator Systems: Crucible Heating Techniques 12.5 Multicomponent Films 12.6 An Introduction to Sputtering 12.7 Physics of Sputtering 12.8 Deposition Rate: Sputter Yield 12.9 High Density Plasma Sputtering 12.10 Morphology and Step Coverage 12.11 Sputtering Methods 12.12 Sputtering of Specific Materials 12.13 Stress in Deposited Layers 12.14 Summary Problems References 13. Chemcial Vapor Deposition 13.1 A Simple CVD System for the Deposition of Silicon 13.2 Chemical Equilibrium and the Law of Mass Action 13.3 Gas Flow and Boundary Layers 13.4 Evaluation of the Simple CVD System 13.5 Atmospheric CVD of Dielectrics 13.6 Low Pressure CVD of Dielectrics and Semiconductors in Hot Wall Systems 13.7 Plasma Enhanced CVD of Dielectrics 13.8 Metal CVD + 13.9 Summary Problems References 14. Exiptaxial Growth 14.1 Water Cleaning and Native Oxide Removal 14.2 The Thermodynamics of Vapor Phase Growth 14.3 Surface Reactions 14.4 Dopant Incorporation 14.5 Defects in Epitaxial Growth 14.6 Slective Growth 14.7 Halide Transport GaAs Vapor Phase Epitaxy 14.8 Incommensurate and Strained Layer Heterooepitaxy 14.9 Metal Organic Chemical Vapor Deposition (MOCVD) 14.10 Advanced Silicon Vapor Phase Epitaxial Growth Techniques 14.11 Molecular Beam Epitaxy Technology 14.12 BCF Theory 14.13 Gas Source MBE and Chemical Beam Epitaxy 14.14 Summary Problems References PART V: PROCESS INTEGRATION 15. Device Isolation, Contacts, and Metallization 15.1 Junction and Oxide Isolation 15.2 LOCOAS Methods 15.3 Trench Isolation 15.4 Silicon on Insulator Isolation Techniques 15.5 Semi-insulating Substrates 15.6 Schottky Contacts 15.7 Implanted Ohmic Contacts 15.8 Alloyed Contacts 15.9 Multilevel Metallization 15.10 Planarization and Advanced Interconnect 15.11 Summary Problems References 16. CMOS Techniques 16.1 Basic Long Channel Device Behavior 16.2 Early MOS Technologies 16.3 The Basic 3 um Technology 16.4 Device Scaling 16.5 Hot Carrier Effects and Drain Engineering 16.6 Processing for Robust Oxides 16.7 Latchup 16.8 Shallow Source/Drains and Tailored Channel Doping 16.9 Summary Problems References 17. GaAs Technologies 17.1 Basic MESFET Operation 17.2 Basic MESFET Technology 17.3 Digital Technologies 17.4 MMC Technologies 17.5 MODFETs 17.6 Optoelectronic Devices 17.7 Summary Problems References 18. Silicon Bipolar Techniques 18.1 Review of Bipolar Devices -- Ideal and Quasi-ideal Behavior 18.2 Second Order Effects 18.3 Performance of BJTs 18.4 Early Bipolar Processes 18.5 Advaned Bipolar Processes 18.6 Hot Electron Effects in Bipolar Transitions 18.7 BiCMOS 18.8 Analog Bipolar Technolgies 18.9 Summary Problems References 19. MEMS (co-authored with G. Cibuzar, University of Minnesota) 19.1 Fundamentals of Mechanics 19.2 Stress in Thin Films 19.3 Mechanical to Electrical Transduction 19.4 Mechanics of Common MEMS Devices 19.5 Bulk Micromachining Etching Techniques 19.6 Bulk Micromachining Process Flow 19.7 Surface Micromachining Basics 19.8 Surface Micromachining Process Flow 19.9 MEMS Actuators 19.10 High Aspect Ratio Microsystems Technology (HARMST) 19.11 Summary Problems References 20. Integrated Circuit Manufacturing 20.1 Yield Prediction and Yield Tracking 20.2 Particle Control 20.3 Statistical Process Control 20.4 Full Factorial Experiments and ANOVA 20.5 Design of Experiments 20.6 Computer Integrated Manufacturing 20.7 Summary Problems References APPENDICES I. Acronyms and Common Symbols II. Properties of Selected Semiconductor Materials III. Physical Constants IV. Conversion Factors V. The Complimentary Error Function VI. F Values VII. SUPREM Commands Index

Review: Semiconductor Piezoresistance for Microsystems

Abstract: Piezoresistive sensors are among the earliest micromachined silicon devices. The need for smaller, less expensive, higher performance sensors helped drive early micromachining technology, a precursor to microsystems or microelectromechanical systems (MEMS). The effect of stress on doped silicon and germanium has been known since the work of Smith at Bell Laboratories in 1954. Since then, researchers have extensively reported on microscale, piezoresistive strain gauges, pressure sensors, accelerometers, and cantilever force/displacement sensors, including many commercially successful devices. In this paper, we review the history of piezoresistance, its physics and related fabrication techniques. We also discuss electrical noise in piezoresistors, device examples and design considerations, and alternative materials. This paper provides a comprehensive overview of integrated piezoresistor technology with an introduction to the physics of piezoresistivity, process and material selection and design guidance useful to researchers and device engineers.

RF-MEMS switches for reconfigurable integrated circuits

Abstract: This paper deals with a relatively new area of radio-frequency (RF) technology based on microelectro-mechanical systems (MEMS). RF MEMS provides a class of new devices and components which display superior high-frequency performance relative to conventional (usually semiconductor) devices, and which enable new system capabilities. In addition, MEMS devices are designed and fabricated by techniques similar to those of very large-scale integration, and can be manufactured by traditional batch-processing methods. In this paper, the only device addressed is the electrostatic microswitch - perhaps the paradigm RF-MEMS device. Through its superior performance characteristics, the microswitch is being developed in a number of existing circuits and systems, including radio front-ends, capacitor banks, and time-delay networks. The superior performance combined with ultra-low-power dissipation and large-scale integration should enable new system functionality as well. Two possibilities addressed here are quasi-optical beam steering and electrically reconfigurable antennas.