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DC magnetron sputtering is a commonly used technique for the fabrication of silicon based electronic devices, since it provides high deposition rates and uniform large area metallization. However, in addition to the thickness uniformity, coating optical uniformity is a crucial need for semiconductor industrial processes, due to the wide use of optical recognition tools. In the silicon-based technology, aluminum is one of the most used materials for the metal contact. Both the pre-deposition substrate cleaning and the sputtering conditions determine the quality and the crystalline properties of the final Al deposited film. In this paper is shown that not all the mentioned conditions lead to good quality and uniform Al films. In particular, it is shown that under certain standard process conditions, Al/Si alloy (1% Si) metallization on a [100] Si presents a non-uniform reflectivity, with a marbled texture caused by flakes with milky appearance. This optical inhomogeneity is found to be caused by the coexistence of randomly orient Al/Si crystal, with heteroepitaxial Al/Si crystals, both grown on Si substrate. Based on the microstructural analysis, some strategies to mitigate or suppress this marbled texture of the Al thin film are proposed and discussed.

OBJECTIVE: Enhanced external counterpulsation (EECP) is a noninvasive, well-tolerated treatment, effective for managing patients with refractory angina pectoris. The aim of this study was to evaluate the efficacy of EECP to relieve symptoms, to decrease myocardial ischaemia and to improve cardiac performance in patients with intractable angina, refractory to surgical and medical treatment. METHODS: Twenty-five patients (24 men and one woman, mean age 65 years) with persistent ischaemia notwithstanding optimal medical therapy or after interventional or surgical procedure, received EECP sessions for 35 h. Each patient underwent dobutamine stress echocardiography before and after treatment. We evaluated modifications in either cardiac systolic or diastolic function, and in wall motion score index. RESULTS: Eighty-four percent of patients showed an increase in at least one functional angina class. We did not observe any significant changes in fractional shortening and diastolic function. Thirty-six percent of patients had a reduction in the area of inducible ischaemia at dobutamine stress echocardiography after treatment. Unfortunately, because of the small sample size, we did not find any statistically significant difference. There was a trend showing that patients who benefited the most were those with the worst systolic function and with severely compromised segmental kinesis (P = NS). CONCLUSIONS: EECP is effective in relieving symptoms in patients with refractory angina and may reduce inducible ischaemia at dobutamine stress echocardiography, especially in patients with reduced systolic function and compromised segmental kinesis.

With the increasing interest in electro-thermal simulation of multi-cellular IGBT structure, the use of PSpice device compact models becomes very attractive because they ensure a good trade-off between accuracy and speed. However, the evaluation of model parameters can be difficult if model doesn't actually reflect the device physics: hence a calibration of parameters is needed to match the static and dynamic device electrical characteristics. We present a calibration procedure for IGBT PSpice model parameters, tested on the PSpice NIGBT model of a 18A-600V PT-planar device: the obtained model is compared with PSpice library one based on physics measured and extracted parameters. Both models are used in a DC-DC buck converter simulation to verify the abilities of calibrated model to better describe the IGBT losses and circuit efficiency in accordance with experimental measurements.