G. Masetti

Modeling of carrier mobility against carrier concentration in arsenic-, phosphorus-, and boron-doped silicon

New carrier mobility data for both arsenic- and boron-doped silicon are presented in the high doping range. The data definitely show that the electron mobility in As-doped silicon is significantly lower than in P-doped silicon for carrier concentrations higher than 1019cm-3. By integrating these data with those previously published, empirical relationships able to model the carrier mobility against carrier concentration in the whole experimental range examined to date (about eight decades in concentration) for As-, P-, and B-doped silicon are derived. Different parameters in the expression for the n-type dopants provide differentiation between the electron mobility in As-and in P-doped silicon. Finally, it is shown that these new expressions, once implemented in the SUPREM II process simulator, lead to reduced errors in the simulation of the sheet resistance values.

On the small-signal behaviour of the MOS transistor in quasistatic operation

Abstract A complete MOST small signal model is proposed, chosen to related most easily to widely used incomplete models. For quasistatic operation, expressions for the model parameters valid for all regions of operation, including weak and moderate inversion, are derived. The predicted bias dependence of the nine model capacitance coefficients, derived starting from the long channel MOST theory recently presented by F. Van de Wiele, is presented and compared to available experimental data.

Failures induced on analog integrated circuits by conveyed electromagnetic interferences: A review

Abstract Failures induced on analog integrated circuits by electromagnetic interference (EMI) will be analyzed with particular emphasis on integrated operational amplifiers built with different technologies. Additionally, the correlation found between EMI susceptibility and large-signal opamp behavior will be discussed. Some criteria for the design of low EMI susceptibility opamps will be derived. Finally, as an application example, the design of a BiCMOS opamp with an extremely low-probability EMI-induced failure will be presented.

On phosphorus diffusion in silicon under oxidizing atmospheres

Phosphorus diffusion in silicon has been carried out in both inert (nitrogen) and oxidizing (90% nitrogen plus 10% oxygen, dry oxygen, steam) atmospheres, over a wide temperature range (1000–1200°C) and for doping concentrations usually encountered in the silicon planar technology. The experimental data, interpreted on the basis of the Kato and Nishi theoretical model taking into account the redistribution phenomena at the moving oxide-silicon interface, show that the phosphorous diffusion coefficient is strongly influenced by the nature of the ambient atmosphere in which the diffusion is carried out. Two different values for the activation energy of the diffusion process, Ei = 3·5 eV for the inert and E0 = 2·5 eV for the oxidizing conditions, have been found. These values seem to confirm the phosphorous diffusion mechanism based on E-centers for the inert case, while for the oxidizing case a different diffusion mechanism should be considered.

A macromodel for integrated all-MOS operational amplifiers

A macromodel for integrated all-MOS operational amplifiers is developed with reference to circuits where the settling behavior of the op amps is of particular concern. Expressions for the values of the elements of the macromodel are obtained from typical measured characteristics. It is shown that the proposed macromodel can satisfactorily predict both small-signal and large-signal behavior of the op amps.

New macromodels and measurements for the analysis of EMI effects in 741 op-amp circuits

Presents the design of two macromodels for the 741 op-amp that prove trustworthy in simulating the consequences of high-frequency, large-amplitude sinusoidal voltages that represent EMI (electromagnetic interference) effects and are applied to the input of inverting and noninverting amplifiers. One of the macromodels accounts for power supply voltage change, reproduces correct voltage waveforms at the main nodes of the full circuit, and gives rise to computer time saving factors of 5 or more in comparison with full device-level simulations. The other comprises the minimum number of components necessary to estimate the DC output voltage only and reduces the simulation time by a further factor of about 5. Extensive experimental results were obtained from laboratory measurements and are compared with the numerical simulations. >

CMOS implementation of an analogically programmable cellular neural network

The criteria for designing the basic building blocks of an analogically programmable cellular neural network (CNN) in a 1.5- mu m CMOS technology are reported. The simulated electrical performances of a 10*10 CMOS CNN, consisting of about 8000 MOS transistors, are presented and discussed. It is shown that the designed CNN can be successfully used to perform such useful functions as noise removal, edge detection, hole filling, shadow detection, and connected component recognition. >

Oxidation-rate dependence of phosphorus diffusivity in silicon

Abstract The diffusion of phosphorus in silicon at 1100°C in inert and three different oxidizing atmospheres has been investigated by using the standard two stages technique, and the results interpreted using the Kato and Nishi theoretical model. A linear relationship has been obtained between the silicon oxidation rate and the induced enhancement of phosphorus diffusivity, in agreement with the hypothesis of - excess interstitials generated at the inward moving oxide-silicon interface. This enhancement has been demonstrated to be practically independent of the distance from the silicon surface. Finally a dual phosphorus diffusion mechanism has been suggested, with a dominant interstitialcy component in oxidizing atmospheres and with a dominant vacancy (E-centre) component in inert atmospheres.

Predictive Deconvolution and Hybrid Feature Selection for Computer-Aided Detection of Prostate Cancer

Computer-aided detection (CAD) schemes are decision making support tools, useful to overcome limitations of problematic clinical procedures. Trans-rectal ultrasound image based CAD would be extremely important to support prostate cancer diagnosis. An effective approach to realize a CAD scheme for this purpose is described in this work, employing a multi-feature kernel classification model based on generalized discriminant analysis. The mutual information of feature value and tissue pathological state is used to select features essential for tissue characterization. System-dependent effects are reduced through predictive deconvolution of the acquired radio-frequency signals. A clinical study, performed on ground truth images from biopsy findings, provides a comparison of the classification model applied before and after deconvolution, showing in the latter case a significant gain in accuracy and area under the receiver operating characteristic curve.

Criteria to reduce failures induced from conveyed electromagnetic interferences on CMOS operational amplifiers

Abstract Electromagnetic interference may cause failures in operational amplifiers. The probability of these failures can be reduced by properly designing the opamps, once the failure mechanism has been discovered. In this paper the design of several integrated CMOS operational amplifiers with a very low-probability of electromagnetic interference (EMI) induced failures is reported. In particular, it is shown that opamps exhibiting low EMI-susceptibility can be obtained only if the influence of some parasitic capacitances in the input stage is compensated and if the opamp response to a large square-wave input signal is made symmetric. Following these guide-lines, we designed the two-stage, the folded cascode and the high-swing folded cascode CMOS opamp structures with an EMI susceptibility of only a few tens of mV up to several hundred MHz when driven with interfering input signals of several volts. Additionally, the effect of process parameters variations on EMI induced failures is discussed.