Modeling and numerical simulation of crystal growth of Si film and heat transport in 3D structure were made for optimization of physical and geometrical parameters used during laser recrystallization. Based on simulations a new concept called micro-absorber was introduced for obtaining defect-free Si films.

To realize a highly efficient small antenna, high-Tc superconductors are adopted to fabricate both a self-resonating helical radiator and a quarter-wave matching circuit. The actual gain and bandwidth measured at 478 MHz using a 1/45-wavelength radiator were respectively 1.5 dBi and 0.35%, indicating that this type of antenna has a high radiation efficiency and a fairly wide bandwidth. It is also confirmed through experiments and theoretical simulations that a decrease in the surface resistance of the radiator more effectively improves the radiation efficiency than a decrease in the surface resistance of the matching circuit.

This paper is concerned with the stress simulation of a LOCOS structure during not only oxidation but also the subsequent cooling down based on viscoelastic stress modeling. A viscoelastic model is successfully applied to the oxide, nitride and silicon substrate for a LOCOS structure. Thermal stress is also taken into account during the cooling down process. The viscoelastic deformation problem of all the three materials for the LOCOS structure are solved by a two-dimensional finite element method. It is the first time to show that the stress values after cooling down to room temperature are much higher than those right after oxidation. It is also shown that varying the cooling down rates results in the different stress values after cooling down.

In recent years, ion implantation has become one of the key techniques in semiconductor fabrication. The annealing of the damage produced during implantation is, however, not fully understood. Ion implantation at high temperatures allows the time-resolved study of implantation-enhanced diffusion. During the process, point defects are generated by the ion implantation and consumed by recombination in the bulk as well as by diffusion to the surface and recombination there. With increasing temperatures, the recombination of point defects, which are acting as diffusion vehicles, results in reduced effective diffusion. Profiles processed above 900 show marked uphill diffusion at the surface caused by large gradients of the point defect concentrations. This uphill diffusion affirms the generally accepted pair diffusion theories. Since the point defects are in steady state even after process times which are short compared to the total process time, we are able to give a qualitative analysis of the dose dependence of the diffusion. By extensive numerical simulations, we could estimate the product of bulk recombination rate and equilibrium concentrations of self-interstitials and vacancies as well as the interface recombination velocity for the self-interstitials. The results obtained are in qualitative agreement with previous work of others. The results demonstrate, in fact, clearly the advantages of the method presented. But due to experimental problems concerning the temperature measurement, which have not been fully resolved up to now, the results have to be considered as crude estimates.

This work describes a new analytical MOSFET model for analog circuit simulation based on the charge-sheet model. The current equation consists of diffusion and drift components, therefore Ids is a smooth function of the applied voltages. Since the original charge-sheet model is valid only for long-channel transistors, it has been further developed to describe quarter-micron MOSFETs by introducing the lateral electric field Ey into the theory. The new model includes these field contributions self-consistently, and describes the drain current of MOSFETs from long to quarter-micron channel lengths with a single model parameter set without discontinuities in derivatives of the drain current Ids. The mobility reduction due to Ey is described by an empirical equation with physical parameter values taken from literature. Only two fitting parameters, the impurity scattering and the surface roughness scattering in the mobility equation, are added to the physical parameters. The subdiffusion lengths are also taken as fitting parameters. Though the new model reduces the number of fitting parameters totally to four, it reproduces measured Ids excellently for MOSFETs with all channel lengths. The model has been included in the parameter extraction program JANUS, which extracts model parameters automatically. The algorithm for parameter extraction is summarized.

We present a new apparent bandgap narrowing model for semiconductor device simulation. The new model is derived from revised data of previous measurements on the apparent bandgap narrowing by using a corrected intrinsic carrier concentration. The revised values reveal sufficient agreement with our theoretical calculation. The new model is implemented in a triangular mesh device simulator TRIMEDES. Simulated BJT current-voltage and current-temperature characteristics using the proposed model reveal excellent agreement with measurements.

We have developed an efficient general-purpose two-dimensional device simulation system which consists of a solver, and pre- and post-processors. This system can easily handle any complicated device having a non-rectangular shape. It can also be applied to compound semiconductor devices with heterojunctions, including optical devices such as laser diodes. In order to handle any device, a new program for construction of device geometry is developed as a preprocessor. It has an efficient graphic interface to reduce the time required to input data for simulations, which is a very time consuming task for complicated devices. A new efficient data structure representing device geometry is introduced in the program. During postprocessing, any physical quantity can be displayed on the multi-window screen. In addition, a general-purpose solver for basic semiconductor equations is implemented in the system. Using this system, any device can be successfully analyzed in a unified manner and the turn-around time for the simulation is significantly reduced.

In this paper, a three part algorithm is employed to obtain stable convergence during stress dependent oxidation simulation using the finite element method is presented. By introducing (1) a reduced integration formulation, (2) an averaging procedure for the mid-side node velocities at the Si/SiO2 interface, and (3) a three-node element to discretize the oxidant diffusion equation, major improvements in achieving stable convergence are realized during stress dependent oxidation simulation. This technique is generally applicable for an oxidation simulator using the finite element method.

In speech output expected as an ideal man-machine interface, there exists an important issue on emotion production in order to not only improve its naturalness but also achieve more sophisticated speech interaction between man and machine. Speech has two aspects, which are prosodic information and phonetic feature. For the purpose of application to natural and high quality speech synthesis, the role of prosody in speech perception has been studied. In this paper, prosodic components, which contribute to the expression of emotions and their intensity, are clarified by analyzing emotional speech and by conducting listening tests of synthetic speech. The analysis is performed by substituting the components of neutral speech (i.e., one with no particular emotion) with those of emotional speech preserving the temporal correspondence by means of DTW. It has been confirmed that prosodic components, which are composed of pitch structure, temporal structure and amplitude structure, contribute to the expression of emotions more than the spectral structure of speech. The results of listening tests using prosodic substituted speech show that temporal structure is the most important for the expression of anger, while all of three components are much more important for the intensity of anger. Pitch structure also plays a significant role in the expression of joy and sadness and their intensity. These results make it possible to convert neutral utterances into utterances expressing various emotions. The results can also be applied to controlling the emotional characteristics of speech in synthesis by rule.

Suppose that there are terminals on two concentric circles, Cin and Cout, with Cin inside of Cout. We are given a set of nets each of which consists of a terminal on Cin and a terminal on Cout. The routing area is the annular region between the two circles. In this paper, we present an O(nk-1) time algorithm for testing whether the given net set is k-layer routable without vias, where k2 and n is the number of nets.

Binaural effects in two measures are studied. One measure is the detectable limen of click sounds under lateralization of diotic or dichotic noise signals, and the other is phoneme articulation score under localization or lateralization of speech and noise signals. The experiments use a headphones system with listener's own head related transfer function (HRTF) filters. The HRTF filter coefficients are calculated individually from the impulse responses due to the listener's HRTF measured in a slightly sound reflective booth. The frequency response of the headphone is compensated for using an inverse filter calculated from the response at the subject's own ear canal entrance point. Considering the speech frequency band in tele-communication systems is not sufficiently wide, the bandwidth of the HRTF filter is limited below 6.2 kHz. However, the experiments of the localization simulation in the horizontal plane show that the sound image is mostly perceived outside the head in the simulated direction. Under simulation of localization or lateralization of speech and noise signals, the phoneme articulation score increases when the simulation spatially separates the phonemes from the noise signals while the total signal to noise ratio for both ears is maintained constant. This result shows the binaural effect in speech intelligibility under the noise disturbance condition, which is regarded as a part of the cocktail party effect.

An optimum placement of capacitors in the layout of Switched Capacitor networks is presented in this paper. The performance of integrated circuits is generally degraded by perturbations of physical parameters of each device and parasitic strays. The optimality imposed in this paper is the minimum degradation of a transfer function with respect to the distribution of capacitance values. A capacitance value per unit area fabricated on a LSI chip is assumed to be perturbed linearly with its x and y coordinates. The capacitor placement is determined so that the effects of such perturbation of capacitances to the overall transfer-characteristics are canceled. As the result, input-output transfer function will stay nominal under the linear perturbation model with arbitrary gradients.

Low-field mobilities and velocity versus electric field relations are among the key input parameters for drift-diffusion simulations of field-effect and bipolar transistors. For example, most device simulations that treat scattering from ionized impurities contain mobilities or velocity versus field relations based on the Born approximation (BA). The BA is insensitive to the sign of the charged impurity and is especially poor for ionized impurity scattering because of the relatively strong scattering of long-wavelength carriers, which have low energies, and therefore violate the validity condition for the BA. Such carriers occur at high symmetry points in the Brillouin zone and are critical for device behavior. There has been a tendency in the past to assume that majority and minority mobilities are equal. This assumption can lead to incorrect interpretations of device data and thereby misleading design strategies based on such simulations. We have calculated the majority electron and minority hole mobilities in GaAs at 300 K for donor densities between 51016 and 11019 cm-3 and the majority hole and minority electron mobilities for acceptor densities between 51016 and 11020 cm-3. We have included all the important scattering mechanisms for GaAs: acoustic phonon, polar optic phonon, nonpolar optic phonon (holes only), piezoelectric, ionized impurity, carrier-carrier, and plasmon scattering. The ionized impurity and carrier-carrier scattering processes have been calculated with a quantum mechanical phase-shift analysis to obtain more accurate matrix elements for these two scattering mechanisms. We compare the total scattering rate for majority electrons due to ionized impurities based on exact phase shifts and on the BA used by Brooks-Herring. We also present additional data that show the differences between the exact phase-shift analyses and the BA for majority electron scattering rates as functions of carrier energy and scattering angle. These results show that the calculated low-field mobilities are in good agreement with experiment, but they predict that at high dopant densities minority mobilities should increase with increasing dopant density for a short range of densities. This effect occurs because of the reduction of plasmon scattering and the removal of carriers from carrier-carrier scattering because of the Pauli exclusion principle. Some recent experiments support this finding. These results are important for device modeling because of the need to have reliable values for the minority mobilities and velocity-field relations.

Unlike a noise removal recursive or averaging filter, this letter presents a temporal filter which attenuates temporal high frequency components and improves visual effects. Although temporal aliasing occurs, the proposed filter proceeds temporal bandlimitation not affected by them. To reduce effects caused by aliasing components, a spatial filtering which is applied along the trajectory of motion is investigated. The proposed filter presents a de-aliasing and effective bandlimiting characteristics as well as reducing of noises.

In this paper, a "hydrodynamic" version of the three-dimensional code HFIELDS-3D is used to achieve a detailed knowledge on the distribution of the substrate current inside a recessed-oxide MOSFET. The physical model features a temperature-dependent formulation of the impact-ionization rate, allowing non-local effects to be accounted for. The discretization strategy relies on the Box Integration scheme and uses suitable generalizations of the Scharfetter-Gummel technique for the energy-balance equation. The simulation results show that the narrow-channel effect has a different impact on drain and substrate currents. Further three-dimensional effects, such as the extra heating of the carriers at the channel edge, are demonstrated.

In this paper, the eigen-function weighted boundary integral epuation method (EW-BIEM) is applied to analyze the dispersion characteristics of various planar transmission lines with finite metallization thickness, such as the micro-strip lines, conductor-backed coplanar waveguides and micro-coplanar striplines for the first time. Due to the choice of the eigen-functions as weighted functions instead of Green's function, the computational time is shortened to a great extent and the singularity problems are also avoided. The difficulty in treating strip thickness can be overcome by considering the 90 edge on the strip as a 90 circular arc whose radius tends to zero. The computational results clearly demonstrate that the effects of finite strip thickness on the propagation properties of these transmission lines can be treated easily and efficiently with this method.

We present schemes for disseminating information in the n-dimensional hypercube with some faulty nodes/edges. If each processor can send a message to t neighbors at each round, and if the number of faulty nodes/edges is k(kn), then this scheme will broadcast information from any source to all destinations within any consecutive n+[(k+l)/t] rounds. We also discuss the case where the number of faulty nodes is not less than n.

The objective of this paper is to provide an overview of the recent developments in the area of speech processing and in particular in the fields of speech coding and speech recognition. The speech coding review covers DPCM coders, model-based vocoders, waveform coders, and hybrid coders. The hybrid coders are described in some detail since they are the subject of current research. Our treatment of speech recognition techniques concentrates on the methodologies for voice recognition and the progress made in speaker independent recognition. In addition, we describe the efforts towards commercial deployment of this technology.

In this paper, we propose a new algorithm for the problem of floorplanning of the mixed design of macro and standard cells. The proposed algorithm which is based on partitioning and slicing approach, uses a modified min-cut bipartitioning heuristic. The heuristic bipartitions a block of a mixture of macro and standard cells to minimize the netcut, which are the number of nets connecting both sub-blocks, with size constraints. A sub-block is a resulting descendant block. Before starting the bipartitioning of the block, the macro cell with the longest side in the block is selected first. Using edges of the selected macro cell, bipartitionings are performed twice fixing the location of the macro cell on one of 4 corners of the block with its rotation and reflection. Bipartitioning of blocks is repeated until each block has either a macro cell or standard cells without macro cells. As a result of bipartitioning, a slicing tree is constructed. Using the proposed floorplan algorithm, we developed an automatic placement and routing tool, Cell Designer, for the mixed design of macro and standard cells. According to the floorplanner, macro cells are placed and standard cells are grouped into standard cell blocks. Standard cells are placed and routed within estimated area of block using conventional tools. They form a fixed-shaped block like a macro cell. Interconnections between the two adjacent blocks are performed with a conventional channel router. The channels and the order of channel routing are determined following the hierarchy of the slicing tree. Cell Designer has a dedicated graphics editor to provide interactive services to users. Experimental results on well-known benchmark data are shown.

In order to realize flexible interaction control between user and information processing system, a special purpose user model is proposed on the basis of the knowledge-based design method of user interface system. The user-specific control knowledge of user-oriented interface environment is represented explicitly in the user model and utilized in the user-oriented interface system. Furthermore, the framework of user-oriented interface environment based on this user model called user-model-driven interface system, is proposed as one of user-adaptive human interface systems, in this paper. According to the proposed framework, a prototype system of the user-model-driven interface system is implemented and the facility of user-specific interaction control based on the user model has been verified with respect to an electronic mail handling task.