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Jens KRAUSE Bernhard SCHMITHUSEN Luis VILLABLANCA Wolfgang FICHTNER
We present several challenging gridding problems for multi-dimensional device and process simulation and discuss how new strategies might contribute to their solution. Formulating grid quality requirements for the standard Scharfetter-Gummel box method discretization in device simulation, we demonstrate how the offsetting techniques compares with quadtree grid generation methods and how they apply to modern device designs. Further we present a grid adaptation approach which respects the grid quality criteria and touch upon the main adaptation difficulties within device simulation. For the 3D moving boundary grids in process simulation we present a new algorithm.
Andreas SCHENK Bernhard SCHMITHUSEN Andreas WETTSTEIN Axel ERLEBACH Simon BRUGGER Fabian M. BUFLER Thomas FEUDEL Wolfgang FICHTNER
RF noise in quarter-micron nMOSFETs is analysed on the device level based on Shockley's impedance field method. The impact of different transport models and physical parameters is discussed in detail. Well-calibrated drift-diffusion and energy-balance models give very similar results for noise current spectral densities and noise figures. We show by numerical simulations with the general-purpose device simulator DESSIS_ISE that the hot-electron effect on RF noise is unimportant under normal operating conditions and that thermal substrate noise is dominant below 0.5 GHz. The contribution of energy-current fluctuations to the terminal noise is found to be negligible. Application of noise sources generated in bulk full-band Monte Carlo simulations changes the noise figures considerably, which underlines the importance of proper noise source models for far-from-equilibrium conditions.