On the design of a reliability circuit simulator

This paper describes the outcome of a study into the feasibility of a reliability circuit simulator for ICs in general and the critical parameters involved in particular. The necessary conditions are formulated that have to be fulfilled before any construction of the reliability simulator is meaningful or can be done at all. It has been found that failure mechanisms in the wear-out regime meet these conditions. Next, a general approach is given to make a simulator. This approach is actually derived from circuit simulator activities on hot carrier degradation and electromigration, respectively. Finally, the different groups of parameters are defined

Extraction of Kinetic Parameters for the Chemical Vapor Deposition of Polycrystalline Silicon at Medium and Low Pressures

The deposition of silicon (Si) from silane (SiH4) was studied in the silane pressure range from 0.5 to 100 Pa (0.005 to1 mbar) and total pressure range from 10 to 1000 Pa using N2 or He as carrier gases. The two reaction paths, namely,heterogeneous and homogeneous decomposition could be separated by varying the amount of wafer area per unit volume(wafer-distance variation) and the SiH4 partial pressure as well as the total pressure. Rate constants were derived by fittingthe experimental results. The heterogeneous reaction path could be described by only the adsorption rate constants ofreactive species and the desorption rate constant of hydrogen using a Langmuir-Hinshelwood mechanism. Hydrogen andphosphine were found to suppress the deposition rate at low silane pressures. At high silane pressures or high totalpressures the unimolecular decomposition of silane dominates. The unimolecular rate constant was found to be one to twoorders larger than literature values based on RRKM analyses of high pressure rate data. The relative efficiency of SiH4-N2and SiH4-He collisions compared with SiH4-SiH4 collisions in the unimolecular gas-phase decomposition of SiH4 has beeninvestigated. Helium was found to be a weak collider compared to silane and nitrogen

Strand plasticity governs fatigue in colloidal gels

Repeated loading of a solid leads to microstructural damage that ultimately results in catastrophic material failure. While posing a major threat to the stability of virtually all materials, the microscopic origins of fatigue, especially for soft solids, remain elusive. Here we explore fatigue in colloidal gels as prototypical inhomogeneous soft solids by combining experiments and computer simulations. Our results reveal how mechanical loading leads to irreversible strand stretching, which builds slack into the network that softens the solid at small strains and causes strain hardening at larger deformations. We thus find that microscopic plasticity governs fatigue at much larger scales. This gives rise to a new picture of fatigue in soft thermal solids and calls for new theoretical descriptions of soft gel mechanics in which local plasticity is taken into account.Comment: 5 pages, 4 figure

Cyclosporiasis Outbreak, Indonesia

We describe an outbreak of Cyclospora cayetanensis infection among Dutch participants at a scientific meeting in September 2001 in Bogor, Indonesia. Fifty percent of the investigated participants were positive for C. cayetanensis. To our knowledge, this outbreak is the first caused by C. cayetanensis among susceptible persons in a disease-endemic area

Sensitive high-performance liquid chromatographic fluorescence assay for the quantitation of topotecan (SKF 104864-A) and its lactone ring-opened product (hydroxy acid) in human plasma and urine

A sensitive reversed-phase high-performance liquid chromatographic fluorescence method is described for the simultaneous determination of topotecan (I) and the hydrolysed lactone ring-opened product hydroxy acid (II) in plasma and for the determination of I in urine. To 250 μl of plasma, a 750-μl volume of cold methanol was added to stabilize the pH-dependent conversion of I into II. In plasma, the lower limit of quantitation (LLQ) for both compounds was 0.10 ng/ml. The between-day variation for I at the LLQ was 7.1% and for II was 5.5%. Prior to injection, urine samples were acidified with orthophosphoric acid and diluted with phosphate-buffered saline (PBS). In urine, the calibration curve for I was linear in the range of 10 to 250 ng/ml and the LLQ was 10 ng/ml. The assay was developed to enable pharmacological analysis of I, in on-going phase I and II studies, in patients with solid tumors

Conventional Radiograph Is Still Advised in the Diagnostic Work-up of a Shoulder Dislocation; a Letter to the Editor

Dear editor: A shoulder dislocation is a common diagnosis at the emergency department, showing an incidence of 23.9 per 100,000 person-years. In the current diagnostic work-up, a radiograph is often used to confirm the dislocation. As radiographs are associated with radiation exposure, the ultrasound has been proposed as an alternative. Therefore, the study by Entezari et al is of great importance in evaluating the applicability of the ultrasound. However, the authors suggest that the ultrasound can be used as an alternative to the radiograph. In our opinion, an important advantage of the radiograph has not been discussed and we question some decisions that were made in terms of methodology. Therefore, we think that this study has to be seen in the light of these remarks