A novel buried-drain DMOSFET structure

Bulk nMOS and pMOS transistors with nominal poly length down to 0.10 μm and minimum effective channel length below 0.1 μm were fabricated. An optimised channel doping by indium and antimony is used to suppress the short channel effect (SCE). The influence of the implant energy, ranging from 3 to 15 KeV, of BF2 and Arsenic S/D shallow extensions on the device performance is investigated. Below a critical energy of 5 KeV, speed performance degrades significantly.

ABSTRACTVertical-type a-Si:H Field Effect Transistors with 1 μm channel length have been investigated. A simple analysis of the FET characteristics indicates that the reduction of the channel length is an effective method to improve the FET characteristics at least up to the channel length of 1 μm. Experimental results showed that the on-resistance is approximately propotional to the channel length and that on off current ratio of the vertical-type FET with 1 μm channel length was more than 104.

The success of resin transfer molding (RTM) depends upon the complete wetting of the fiber preform. Effective mold designs and process modifications facilitating the improved impregnation of the preform have direct impact on the successful manufacturing of parts. Race tracking caused by variations in permeabilities around bends, corners in liquid composite molding (LCM) processes such as RTM have been traditionally considered undesirable, while related processes such as vacuum assisted RTM (VARTM) and injection molding have employed flow channels to improve the resin distribution. In this paper, studies on the effect of flow channels are explored for RTM through process simulation studies involving flow analysis of resin, when channels are involved. The flow in channels has been modeled and characterized based on equivalent permeabilities. The flow in the channels is taken to be Darcian as in the fiber preform, and process modeling and simulation tools for RTM have been employed to study the flow and pressure behavior when channels are involved. Simulation studies based on a flat plate indicated that the pressures in the mold are reduced with channels, and have been compared with experimental results and equivalent permeability models. Experimental comparisons validate the reduction in pressures with channels and validate the use of equivalent permeability models. Numerical simulation studies show the positive effect of the channels to improve flow impregnation and reduce the mold pressures. Studies also include geometrically complex parts to demonstrate the positive advantages of flow channels in RTM.

This chapter provides an overview of value-added production using extremophiles as well as the advantages and challenges for process development in a biorefinery concept. The chapter then shows a modeling framework that includes metabolic flux modeling, growth kinetics, and bioreactor models as well as process simulation. The model results are the basis for optimization, economic analysis, and life cycle assessment. The tools are applied to the production of poly-3-hydroxybutyrate (PHB) by using the halophilic bacteria Halomonas sp. The results highlighted the importance of relating models at the various scales and to look at the whole process picture to optimize the economic and environmental performances of the resulting biorefinery process. In the optimized process, the minimum PHB selling price was $7.05 per kg and the reduction in greenhouse gas emissions was 90%, with 0.708 kg CO-eq per kg of PHB. These results showed the potential for using halophilic bacteria to make PHB production competitive in terms of economics and environmental impacts. This also shows how extremophile processing will play a key role in making biorefineries more profitable and sustainable.

A simultaneous combination of scanning Kelvin probe microscopy and scanning atomic force microscopy has been applied to the problem of profiling dopant concentrations in two dimensions in silicon microstructures. By measuring the electrochemical potential difference which minimizes the electrostatic force between probe tip and sample surface, the work-function difference between the tip and surface is estimated. To the extent that this work-function difference is a consequence of the dopant concentration at or near the sample surface, doping profiles are inferred from the measurement. Structures examined and presented here include contact holes, and the technologically significant lightly doped drain of a metal–oxide–silicon field-effect transistor. Using this methodology, one can distinguish relative changes in dopant concentration with lateral resolution less than 100 nm. Sample preparation is minimal, and measurement time is fast compared to other techniques. The measurements have been compared to predictions based on two- and three-dimensional process and device simulation tools. The comparisons show that the technique is sensitive to changes in dopant concentration, from ≊1015 to 1020 cm−3, of less than 10% at these size scales. Suggestions to resolve absolute dopant concentration are made.

Integration of process, device and circuit simulation tools is desirable in modern process development and circuit design, as it allows rapid assessment of the impact of a new process or process change on circuit performance, [1]. This paper presents an efficient scheme for the extraction of MOSFET linear region SPICE level 3 parameters from numerical device simulations. Carrier concentrations, potential and mobility are used to derive a total of seven linear region parameters from three off-state bias points. This is in contrast to standard curve fitting techniques where twenty or, more on-state bias points would typically be used to obtain the required parameters.

This paper gives an overview of predictive Technology CAD tools for simulating and modeling the fabrication and electrical behavior of integrated circuits. Recent trends in the integration of process, device, and circuit simulation tools, and the current emergence of UNIX based computing environments of networked workstations make possible user-friendly, task-based CAD systems for technology optimization, characterization, and cell design.

The aggressive downscaling of FET devices (FinFET, NanowireFET, NanosheetFET, to name a few) in past years has put a great emphasis on the need to come up with properly calibrated process and device simulation tools to predict performances, suggest processing options and even understand failure mechanisms. As their modeling is complex with multiple calibration parameters, adequate two- and three-dimensional characterization techniques have been identified as a necessity to achieve an accurate modeling and calibration of the complex physical mechanisms for scaled devices. In such scaled devices even the smallest variations of the structure dimensions (i.e., width or length, local interconnect or spacer, source/drain epi volumes, etc.), carrier distribution and/or activation rate can cause significant variations in the electrical properties.

TCAD software needs equipment input settings and models to create the process environment for process and device simulation tools like TSUPREM4 and MEDICI. After optimisation the next step is the circuit simulation and design using software packages like SPICE. First using design of experiments-DOE and response surface modelling-RSM techniques we optimise the MOSFET characteristics and then we compare the transfer characteristics of n-type MOSFET, biased in the linear region, and obtained from package respectively TSUPREM4 and MEDICI with transfer characteristics from PSPICE. Using the PSPICE second level model for MOS transistor we obtain a good fit with MEDICI transfer characteristics.

Computational model of mesoscopic structure of concrete for simulation of fracture processes

A novel two-dimensional (2D) process simulator has been developed which can handle local oxidation, implantation through arbitrary mask edges, nonplanar surfaces, and high concentration diffusion. Through coupling of 2D process and device simulators, the sensitivity of perimeter junction capacitance and breakdown voltage to variations in boron channel-stop implantation dose and local oxidation time has been simulated for a standard NMOS technology. Experimental results using test structures have confirmed the simulations. It is shown that simple power-law dependencies as a function of the process variables give good agreement with the data.

Direct patterning of silver electrodes with 2.4 μm channel length by piezoelectric inkjet printing

In a 1 µm Si-gate technology, channel length and temperature have a strong impact on the electrical device parameters. Experimental data on the influence of the channel length and the temperature on threshold voltage, breakdown voltage and subthreshold currents are presented for different channel dopings and S/D junction depths. The results are discussed with regard to the electrical device tolerances and to limitations in standard Si-gate technologies.

Integration of life cycle assessment software with tools for economic and sustainability analyses and process simulation for sustainable process design

The characterization of transistor mismatch in a standard 0.7 µm CMOS technology is presented. A new method for matching parameter extraction has been used. Mismatch parameters based on measurements on 10000 nMOS and 10000 pMOS transistors have been extracted. It is observed that the threshold voltage mismatch linear dependency on the inverse of the square root of the effective channel area no longer holds for transistors of 0.7 µm channel length. An extended model based on the physical causes of threshold voltage mismatch is proposed. Contrary to the established theory, it is observed that transistors with channel length below 1 µm have less current mismatch than what is predicted by a linear relationship with the channel area.