Defect reduction in Cu dual damascene process using short-loop test structures

This paper outlines the defect reduction measures performed during the development of a 130-nm Cu dual-damascene process. The test methodology, using short-loop test structures, included defect tracing, overlaying defect data and electrical measurement data, physical analyses based on these results, and analyses of defect size distribution. While the defect size distributions for large-scale integration processes are considered to depend on x/sup -k/, the distribution for the Cu dual-damascene process is found to be different and is instead characterized by a cumulative distribution described by the composition of several Lorentzian functions. Using these procedures, defect densities were successfully reduced by 50% in half the time taken previously and without the need for actual products.     

A numerical integration scheme for special finite elements for the Helmholtz equation

The theory for integrating the element matrices for rectangular, triangular and quadrilateral finite elements for the solution of the Helmholtz equation for very short waves is presented. A numerical integration scheme is developed. Samples of Maple and Fortran code for the evaluation of integration abscissæ and weights are made available. The results are compared with those obtained using large numbers of Gauss–Legendre integration points for a range of testing wave problems. The results demonstrate that the method gives correct results, which gives confidence in the procedures, and show that large savings in computation time can be achieved. Copyright © 2002 John Wiley & Sons, Ltd.     

Introduction to the Journal on Digital Libraries special issue on Asian digital libraries

International Journal on Digital Libraries -     

Postoperative epidural fentanyl administration in patients for hysterectomy with para-aortic lymph node resection

Endurance training has long been known to improve the individual's resistance to exercise-induced hypoglycemia. Traditionally attributed to a reduction in glucose uptake subsequent to enhanced fat oxidation, this issue has only recently been directly addressed. This paper briefly reviews the evidence for reduced glucose uptake versus enhanced glucose production in the improved hypoglycemic resistance following training. While whole body glucose removal and production may be reduced following training, this has only been demonstrated under exercising conditions in which glycemia demonstrates little deviation from rest. Under exercise conditions where untrained animals demonstrate substantial reductions in blood glucose, training enhanced hypoglycemic resistance has been shown to result entirely from enhanced glucose production via gluconeogenesis. Using the in situ perfused liver preparation, the authors have provided direct evidence for a training enhanced hepatic gluconeogenic capacity. The site of adaptation within the gluconeogenic pathway has now been constrained to below the level of the triose phosphates. Lack of evidence for suppressed skeletal muscle glucose uptake following training, a uniform observation for humans and rats, is also discussed. It is concluded that the improved hepatic gluconeogenic capacity of endurance trained individuals, at least in rats, is critical to their demonstrated resistance to exercise-induced hypoglycemia.     

A 1.5 V, 4.1 mW dual-channel audio delta-sigma D/A converter

The paper describes a stereo digital-to-analog converter intended for portable digital-audio which operates at 1.5 V and consumes only 4.1 mW. A 15-level quantization, third-order delta-sigma was employed to reduce digital operation speed, relax out-of-band filtering requirements, and enhance immunity to clock jitter. The use of direct charge transfer switched-capacitor technique in the multibit reconstruction DAC reduces kT/C noise and element mismatch without increase of power dissipation. The data weighted averaging algorithm suppresses nonlinearity caused by capacitor mismatch by first-order noise-shaping, thereby making mismatch-induced noise negligible. The stereo audio DAC achieves 90 dB dynamic range and 81 dB peak signal-to-noise-plus-distortion ratio over a 20 kHz passband. The 5.3 mm ² chip is fabricated in a 0.6 μm CMOS technology which includes low-threshold devices     

Thermal and mechanical stability of soldering QFP with Sn-Bi-Ag lead-free alloy

Thermal stability of the circuit boards with a quad flat package (QFP) soldered with Sn-58wt%Bi-(0, 0.5 and 1.0) wt% Ag and their microstructural features were evaluated. The addition of 1.0 wt% Ag causes the formation of large primary Ag/sub 3/Sn precipitates in the solder while no primary Ag/sub 3/Sn is found in Sn-57Bi-0.5Ag. Thermo-Calc calculation indicates that the lowest limit content for the formation of primary Ag/sub 3/Sn is about 0.8 wt%. Heat-exposure below 100/spl deg/C has no serious degradation on the joint structure for all solders. Heat-exposure at 125/spl deg/C caused serious degradation in joint strength for all alloys. The contamination of Pb from Sn-Pb surface plating on the components reduces the interface tolerance by forming ternary Sn-Pb-Bi phase melting at low temperature. Thermal fatigue between -20 and 80/spl deg/C does not have any significant influence on joint structure.