Institute for Microelectronics

We present a modular tool chain for high performance CFD simulations of pulsatile blood flow in intracranial aneurysms. We describe a path from in-situ imaging (ie. CT and MRI) to flow simulations and show different modules for obtaining anatomically accurate and allover smooth meshes suitable for computed fluid dynamics (CFD) as well as methods for computing the blood flow in a robust and high performing way.

We present a web application for the simulation of a biological system. An electrically active fish and the corresponding charge relaxation derived from the Maxwell equations are presented. The transition from the equations to the numerical methods is performed with a finite volume discretisation scheme. The final approach to solve the system of resulting equations makes use of a high speed generic scientific simulation environment. The ability to delegate calculations to other hosts further ensures the high performance levels achieved by the highly optimised simulations.

Charge trapping in the gate oxide of nanoscale MOSFETs featuring an 'atomistic' channel doping profile has been revealed as a key concept to explain the RTN and BTI phenomena strongly affecting contemporary technology transistors performance. By means of a 2D Wigner function approach, in this paper we investigate the trapping of a single electron in the gate oxide of a 25nm transistor including the scattering effects due to discrete dopants in the channel. We demonstrate the ability of our simulation methodology to capture not only the quantum nature but also the transient behavior of charge-trapping and scattering phenomena.

We present a novel methodology for characterization of sub-quartermicron CMOS technologies. It involves process calibration, device calibration employing twodimensional device simulation and automated Technology Computer Aided Design (TCAD) optimization, and, finally, transient mixed-mode deviceicircuit simulation. The proposed methodology was tested on 0.25 p m technology and applied to 0.13 p m technology in order to estimate ring oscillator speed. The simulation results show an excellent agreement with available experimental data.

We present results of fully two-dimensional numerical simulations of silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) in comparison with experimental data. Among the critical modeling issues discussed in the paper, special attention is focused on the description of the anisotropic majority/minority electron mobility in strained SiGe grown in Si. #

The effect of uniaxial-strain, band-structure, mobility, effective masses, density of states, channel orientation and highfield transport on the drive current, off-state leakage and switching delay in nano-scale, Silicon (Si) and Germanium (Ge), p-MOS DGFETs is thoroughly and systematically investigated. To accurately model and capture all these complex effects, different simulation techniques, such as the Non-local Empirical Pseudopotential method (bandstructure), Full-Band Monte-Carlo Simulations (transport), 1-D Poisson-Schrodinger (electrostatics) and detailed Band-To-Band-Tunneling (BTBT) (including bandstructure and quantum effects) simulations, were used in this study.

When applied to partially depleted SOI MOSFETs, the energy transport model predicts anomalous output characteristics. The effect that the drain current reaches a maximum and then decreases is peculiar to the energy transport model. It is not present in drift-diffusion simulations and its occurrence in measurements is questionable. The effect is due to an overestimation of the diffusion of channel hot carriers into the floating body. A modified energy transport model is proposed which describes hot carrier diffusion more realisticly and allows for proper simulation of SOI MOSFETs.

We present the state-of-the-art in simulation for industrial application of heterostructure devices based on the SiGe/Si material system. The work includes a detailed comparison of device simulators and current transport models to be used, and addresses critical modeling issues. Results from two-dimensional hydrodynamic analyses of SiGe-heterojunction bipolar transistors (HBTs) with MINIMOS-NT are presented in good agreement with measured data. The examples are chosen to demonstrate technologically important issues which can be addressed and solved by device simulation. #

For the needs of high electron mobility transistors (HEMTs) optimization a reliable software simulation tool is required. Due to the high electric field in the device channel a hydrodynamic approach is used to properly model the electron transport. We modify an existing hydrodynamic mobility model in order to achieve a better agreement with Monte Carlo (MC) simulation data and measured DC and AC characteristics of AlGaN/GaN HEMTs.

The effects of bandgap narrowing due to stress generated during Shallow Trench Isolation (STI) are analyzed. Reverse-bias junction leakage and capacitance measurements are correlated to results from device simulation. A locally varying stress dependent bandgap model is implemented to understand the influence of stress effects. Increases in both junction capacitance and leakage agree well with experiments. Results of leakage and capacitance on the 0.18 m and 0.09 m technologies indicate that effects of process induced stress on device behavior need careful attention.

A stochastic model of the resistive switching mechanism in bipolar metal-oxide based resistive random access memory (RRAM) is presented. The distribution of electron occupation probabilities obtained is in agreement with previous work. In particular, a low occupation region is formed near the cathode. Our simulations of the temperature dependence of the electron occupation probability near the anode and the cathode demonstrate a high robustness of the low occupation region. This result indicates that a decrease of the switching time with increasing temperature cannot be explained only by reduced occupations of the vacancies in the low occupation region, but is related to an increase of the mobility of the oxide ions. A hysteresis cycle of RRAM switching simulated with the stochastic model including the ion dynamics is in good agreement with experimental results.

We present a modular tool chain for high performance CFD simulations of pulsatile blood flow in intracranial aneurysms. We describe a path from in-situ imaging (ie. CT and MRI) to flow simulations and show different modules for obtaining anatomically accurate and allover smooth meshes suitable for computed fluid dynamics (CFD) as well as methods for computing the blood flow in a robust and high performing way.

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