The space- and time-resolved distributions of charge carriers and temperature in the interior of microstructured semiconductor devices have become accessible to measurement as a variety of internal laser probing techniques has been become available. For a comprehensive theoretical analysis of these novel characterization methods, a physically rigorous model for simulating the entire measurement process is presented in this work. Major steps are the electrothermal device simulation of the sample's operating behavior and the calculation of optical-wave propagation through the sample, the lenses, and the aperture holes. We propose a numerically efficient algorithm for simulating wave propagation in large computational domains. The decisive step is the suitable choice of the computational variables which enables a significantly coarser discretization mesh without loosing accuracy. To support the design and the optimization of the experiments, the concept of "virtual experiments" is introduced as the key strategy for a quantitative analysis of the measurement techniques. As an application example, backside laser probing is discussed. It is shown that this technique provides a large measurement range as well as an excellent spatial resolution and, therefore, constitutes a powerful characterization method for a large multitude of different microstructures.

The electrical characteristics of modern VLSI and ULSI device structures may be significantly altered by self-heating effects. The device modeling of such structures demands the simultaneous simulation of both the electrical and the thermal device behavior and their mutual interaction. Although, at present, a large number of multi-dimensional device simulators are available, most of them are based on physical models which do not properly allow for heat transport and other nonisothermal effects. This paper, demonstrates that the numerical process/device simulator TRENDY provides a solid base for nonisothermal device simulation, as a physically rigorous device model of carrier and heat transport has been incorporated in the TRENDY program. With respect to the boundary conditions, it is shown that inclusion of an artificial boundary material relaxes some fundamental physical inconsistencies resulting from the assumption of ideal ohmic contact boundaries. The program TRENDY has been used for studying several nonisothermal problems in microelectronics. As an example, the authors consider an ultra-thin SOI MOSFET showing that the negative slopes in the V/sub ds//spl minus/I/sub ds/ characteristics are caused by the temperature-dependence of the electron saturation velocity.>

A treatment of the self-heating problem is presented. It is based on the laws of phenomenological irreversible thermodynamics (e.g. Onsager's relations and conservation of total energy) and is also consistent with the physical models usually considered in the isothermal drift diffusion approximation. The classical isothermal device equations are extended and completed by a generalized heat-conduction equation involving heat sources and sinks which, besides Joule and Thomson heat, reflect the energy exchanged through recombination (radiative and nonradiative) and optical generation. Thus the extended model also applies to direct semiconductors (e.g., optoelectronic devices) and accounts for effects caused by the ambient light intensity. It fully allows for low temperature since the case of incomplete ionization of donors and acceptors (impurity freeze-out) is properly incorporated in the theory. A critical comparison with previous work is made, showing that, in the steady state, some of the heuristic models of heat generation, thermal conductivity, and heat capacity could indeed approximate the correct results within an error bound of 1-10%. In the transient regime, however, none of the models used previously seems to be reliable, particularly, if short switching times (>