device simulation

Device Simulation Overview Device simulation uses numerical methods to solve semiconductor physics equations (Poisson's equation, carrier continuity, drift-diffusion or hydrodynamic transport) on a meshed device structure to predict transistor electrical behavior without fabricating silicon. What Device Simulation Solves - Poisson's Equation: Relates electrostatic potential to charge distribution (dopants, free carriers). - Electron Continuity: Conservation of electron current with generation/recombination. - Hole Continuity: Conservation of hole current with generation/recombination. - Transport Models: Drift-diffusion (standard), hydrodynamic (includes carrier heating), Monte Carlo (most accurate, slowest). Key Outputs - I-V Characteristics: Drain current vs. gate voltage (transfer curve), drain current vs. drain voltage (output curve). - Threshold Voltage (Vt): Extracted from transfer curve. - Subthreshold Slope (SS): Steepness of off-to-on transition. - DIBL: Drain-Induced Barrier Lowering (short-channel effect metric). - Capacitances: Gate, overlap, junction capacitances for circuit simulation. - Band Diagrams: Energy band structure across the device. - Current Flow: Visualize current density and path through the device. Applications - Technology Development: Optimize device architecture (FinFET, nanosheet, CFET) and doping profiles before silicon. - DTCO: Design-Technology Co-Optimization—co-optimize device and standard cell together. - SPICE Model Extraction: Generate compact model parameters for circuit simulators from device simulation data. - Reliability: Simulate HCI, NBTI, TDDB degradation mechanisms. Tools - Synopsys Sentaurus Device (SDevice): Industry standard. - Silvaco Atlas: Strong for power devices, III-V compounds. - Simulation time: Minutes to hours per bias point depending on mesh complexity and physics models enabled.