Microtransducer CAD Physical and Computational Aspects

Computer-aided-design (CAD) of semiconductor microtransducers is relatively new in contrast to their counterparts in the integrated circuit world. Integrated silicon microtransducers are realized using microfabrication techniques similar to those for standard integrated circuits (ICs). Unlike IC devices, however, microtransducers must interact with their environment, so their numerical simulation is considerably more complex. While the design of ICs aims at suppressing "parasitic" effects, microtransducers thrive on optimizing the one or the other such effect. The challenging quest for physical models and simulation tools enabling microtransducer CAD is the topic of this book. It is intended as a text for graduate students in Electrical Engineering and Physics and as a reference for CAD engineers in the microsystems industry. This text evolved from a series of courses offered to graduate students from Electrical Engineering and Physics. Much of the material in the book can be presented in about 40 hours of lecture time. The book starts with an illustrative example which highlights the goals and benefits of microtransducer CAD. This follows with a summary of model equations describing electrical transport in semiconductor devices and microtransducers in the absence of external fields. Models treating the effects of the external radiant, magnetic, thermal, and mechanical fields on electrical transport are then systematically introduced. To enable a smooth transition into modeling of mechanical systems, an abridged version of solid structural and fluid mechanics is presented, whereby the focus is on pertinent model equations and boundary conditions. This follows with model equations and boundary conditions relevant to various types of mechanical microactuators including electrostatic, thermal, magnetic, piezoelectric, and electroacoustic. The book concludes with a glimpse into SPICE simulation of the mixed-signal microsystem, i.e., microtransducer plus circuitry. Where possible, the model equations are supplemented with tables and/or graphs of process-dependent material data to enable the CAD engineer to carry out simulations even when reliable material models are not available. IVZ LANG: Introduction: Modeling and Simulation of Microtransducers; Illustrative Example; Progress in Microtransducer Modeling; References.- Basic Electronic Transport: Poisson's Equation; Continuity Equations; Carrier Transport in Crystalline Materials and Isothermal Behavior; Electrical Conductivity and Isothermal Behavior in Polycrystalline Materials; Electrical Conductivity and Isothermal Behavior in Metals; Boundary and Interface Conditions; The External Fields - What Do They Influence?; References.- Radiation Effects on Carrier Transport: Reflection and Transmission of Optical Signals; Modeling Optical Absorption in Intrinsic Semiconductors; Absorption in Heavily-Doped Semiconductors; Optical Generation Rate and Quantum Efficiency; Low Energy Interactions with Insulators and Metals; High Energy Interactions and Monte Carlo Simulations; Model Equations for Radiant Sensor Simulation; Illustrative Simulation Example - Color Sensor; References.- Magnetic-Field Effects on Carrier Transport: Galvanomagnetic Transport Equation; Galvanomagnetic Transport Coefficients; Equations and Boundary Conditions for Magnetic Sensor Simulation; Illustrative Simulation Example - Micromachined Magnetic Vector Probe; References.- Thermal Non-Uniformity Effects on Carrier Transport: Non-Isothermal Effects; Electrothermal Transport Model; Electrical and Thermal Transport Coefficients; Electro-Thermo-Magnetic Interactions; Heat Transfer in Thermal Microstructures; Summary of Equations and Computational Procedure; Illustrative Simulation Example - Micro Pirani Gauge; References.- Mechanical Effects on Carrier Transport: Piezoresistive Effect; Strain and Electron Transport; Strain and Hole Transport; Piezojunction Effect; Effects of Stress Gradients; Galvano-Piezo-Magnetic Effects; The Piezo Drift-Diffusion Transport Model; Illustrative Simulation Example - Stress Effects on Hall Sensors; References.- Mechanical and Fluidic Signals: Definitions; Model Equations for Mechanical Analysis; Model Equations for Analysis of Fluid Transport; Illustrative Simulation Example - Analysis of Flow Channels; References.- Micro-Actuation: Transduction Principles; State-of-the-Art and Preview; Electrostatic Actuation; Thermal Actuation; Magnetic Actuation; Piezoelectric Actuation; Electroacoustic Transducers; Computational Procedure and Coupling; Illustrative Example - CMOS Micromirror.- Microsystem Simulation: Electrical Analogues for Mixed-Signals and Historical Developments; Circuit Modeling and Implementation Considerations; Lumped Analysis: Illustrative Example - Electrostatic Micromirror; Distributed Analysis: Illustrative Example - Flow Microsensor; References.- Subject Index.