An extraction method to determine interconnect parasitic parameters

Interconnect parasitic parameters in integrated circuits have significant impact on circuit speed. An accurate monitoring of these parameters can help to improve interconnect performance during process development, provide information for circuit design, or give useful reference for circuit failure analysis. Existing extraction methods either are destructive (such as SEM measurement) or can determine only partial parasitic parameters (such as large capacitor measurement). In this paper, we present a new method for extracting interconnect parasitic parameters, which can simultaneously determine the interlayer and intralayer capacitances, line resistance, and effective line width. The method is based on two test patterns of the same structure with different dimensions. The structure consumes less wafer area than existing methods. The method shows good agreement with SEM measurement of dielectric thickness in both nonglobal planarized and chemical-mechanical polished processes, and gives accurate prediction of the process spread of a ring oscillator speed over a wafer     

A multiple-switch high-voltage DC-DC converter

Series connection of power devices has evolved into a mature technique and is widely applied in HV DC power systems. Static and dynamic voltage balance is ensured by shunting individual devices with dissipative snubbers. The snubber losses become pronounced for increased operating frequencies and adversely affect power density. Capacitive snubbers do not exhibit these disadvantages, but they require a zero-voltage switching mode. Super-resonant power converters facilitate the principle of zero-voltage switching. A high-voltage DC-DC power converter with multiple series-connected devices is proposed. It allows the application of nondissipating snubbers to assist the voltage sharing between the multiple series-connected devices and lowers turnoff losses. Simulation results obtained with a circuit simulator are validated in an experimental power converter operating with two series-connected devices. The behavior of the series connection is examined for MOSFETs and IGBTs by both experimental work with a 2 kW prototype and computer simulation. Applications can be found in traction and heavy industry, where the soft-switching power converter is directly powered from a high-voltage source     

Performance analysis of a solar-assisted swimming pool heating system

This paper deals with feasibility studies for a solar-assisted heating system for the University of Miami's Aquatic Center using the simulation program TRNSYS. The Aquatic Center is composed of an outdoor olympic size swimming pool and locker room building. The solar heating is accomplished by employing hot water generated by heat exchange with the solar collector working fluid. Two thermal storage tanks are employed for the collector and domestic use. The performance of the system is analyzed from both thermodynamic and economic standpoints and general conclusions are reached.     

Studies on elemental tellurium under high pressure

A non-linear behaviour in the resistance of tellurium as a function of pressure has been observed. At each pressure the resistance shows a time variation. At lower pressures, the normalized resistance increases with time, and at higher pressures, the normalized resistance decreases exponentially as a function of time. This change in behaviour with respect to time occurs in the region of the steepest descent in the resistance versus pressure plot. However, the magnitude of the change in the resistance with time is small compared to a change in the resistance with pressure. The origin of this behaviour is suggested to be linked with the generation and annealing of localized charged defects. This revised version was published online in November 2006 with corrections to the Cover Date.     

Oxidation of TiAl based intermetallics

The high temperature oxidation behaviour of the binary and ternary alloys of the Ti–48Al system was studied at different temperatures. The primary objectives of this work were the establishment of the activation energies, the migration tendencies of the alloy species, mechanism of oxidation and chemistry of the oxide scales. The ternary additions were Cr (1.5 at 19%), V (2.2 at%), W (0.2 at%) and Mn (1.4 at%). The addition of ternary additions did not play a significant role in the oxidation behaviour at 704°C. At 815°C the alloys with Cr and V exhibited linear oxidation behaviour with large weight gains while the base Ti–48Al alloys exhibited the best behaviour. At 982°C the Mn-containing alloy was the worst, exhibiting a linear oxidation behaviour while the alloy with V and W and the base alloy with 400 p.p.m. oxygen exhibited the best oxidation behaviour. At 982°C the outermost oxide layer in contact with air is always near stoichiometric TiO₂. In all the alloys a layer of porosity is created just below the outer TiO₂ layer by the Kirkendall mechanism due to the rapid outward diffusion of Ti atoms. The addition of trivalent atoms like Cr in small amounts appear to be detrimental to the oxidation process as they can generate additional oxygen vacancies while the addition of atoms with valence of 5, such as V, and 6, such as W, appear to have beneficial effect on the oxidation behaviour at 982°C by tying up oxygen vacancies. This revised version was published online in November 2006 with corrections to the Cover Date.     

Changes in the mineral phases during the processing of a copper sulfide concentrate

Mineralogical, granulometric, and phase compositions of the copper sulfide concentrate of the Erdenet deposit (Mongolia) have been studied. It is shown that the concentrate has a high chemical stability against the interaction with sulfuric solutions after both a preliminary oxidizing roasting and mechanoactivation in a planetary mill (in dry and wet regimes of milling).     

Calculation of neutron importance function in fissionable assemblies using Monte Carlo method

The purpose of the present work is to develop an efficient solution method for the calculation of neutron importance function in fissionable assemblies for all criticality conditions, based on Monte Carlo calculations.     

A micromachined electrochemical sensor for free chlorine monitoring in drinking water.

In this work, we designed, fabricated and tested a disposable, flow-through amperometric sensor for free chlorine determination in water. The sensor is based on the principle of an electrochemical cell. The substrate, as well as the top microfluidic layer, is made up of a polymer material. The advantages include; (a) disposability from low cost; (b) stable operation range from three-electrode design; (c) fluidic interconnections that provide on line testing capabilities; and (d) transparent substrate which provides for future integration of on-chip optics. The sensor showed a good response and linearity in the chlorine concentration ranging from 0.3 to 1.6 ppm, which applies to common chlorination process for drinking water purification.     

Low-threshold single-quantum-well InGaAs/GaAs lasers grown bymetal-organic chemical vapor deposition on structure substrates

Low-threshold current (as low as 3.0 mA) and high-external efficiency (≈88%) InGaAs/GaAs lasers emitting at 1 μm under a stable fundamental transverse mode were obtained by using the temperature engineered growth technique for the growth on prepatterned substrates