Browsing by Author "Poggi, Antonella"

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    Deep level transient spectroscopy study of the damage induced in n-type silicon by a gate oxide etching in a CHF3/Ar plasma
    (Journal of vacuum science & technology B, 1997-06) Adegboyega, G.; Perez, I.V; Poggi, Antonella; Susi, E
    Deep level transient spectroscopy was used to detect the presence of deep levels correlated to the defects induced in the Si substrate by a CHF 3 /Ar dry etch of a 550 Å gate oxide as a function of the rf power. Several energy levels were observed; some of them were due to the processing before the dry etching. Three traps produced by the dry etching, with Arrhenius plot activation energies, respectively, E na1 =350  meV , E na2 =220  meV , and E na3 =100  meV , and capture cross sections around 10-20  cm 2 were detected. The correlation with the surface recombination velocity variations and the F and C diffusion in the Si substrate was investigated. © 1997 American Vacuum Society
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    Electrical Properties of Silver Impurities and their Annealing Behaviour in p-Type Fz Silicon
    (Journal de Physique III, 1691-12) Adegboyega, G.A; Passari, L; Butturri, Maria Angela; Poggi, Antonella
    The electrical activity of silver as well as its annealing properties in 10 Omega cm p-type Fz silicon substrate are studied by means of the four-point probe and minority carrier lifetime measurements. Silver atom concentration in the range 10^{14} to 10^{15} cm^{-3} consistently showed a donor type behaviour in the material and its presence led to a reduction of up to two orders of magnitude in the lifetime of minority carriers by the formation of deep-level traps. Isochronal annealing of silver contaminated specimens showed some gettering of the Ag impurities with resulting temperature dependent changes in the resistivity as well as the minority carrier lifetime values. Analysis of our results shows that a large fraction of the silver impurity atoms present forms the deep level defects and both the deep- and donor-levels appear to originate from the same source
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    Intrinsic gettering of Cr impurities in p-type Cz silicon
    ( physica status solidi (a, 1990-09) Adegboyega, G.A; Poggi, Antonella
    The gettering of chromium impurities by means of high temperature oxygen precipitates is studied by means of resistivity, lifetime, and infrared absorption spectroscopy measurements. The results show that the density of interstitial oxygen, following an oxygen precipitation step, is rather low, and the presence of this interstitial oxygen is closely connected with the formation of the so-called new donor defect. Most of the high temperature (T = 1000°C) oxygen precipitates seem to appear in the form of SiO2 and there is a strong evidence of a redissolution of the oxygen precipitates due to Cr diffusion. The presence of this high temperature oxygen precipitate shows a high efficiency in the gettering of Cr impurities.Das Gettern von Chromverunreinigungen mittels Hochtemperatur-Sauerstoffpräzipitaten wird mittels Widerstands-, Lebensdauer- und Infrarotspektroskopiemessungen untersucht. Die Ergebnisse zeigen, daß die Dichte des Zwischengittersauerstoffs nach dem Sauerstoffpräzipitationsschritt ziemlich niedrig ist, und die Anwesenheit dieses Zwischengittersauerstoffs eng verbunden ist mit der Bildung von sogenannten „new-Donor”-Defekten. Die meisten der Hochtemperatursauerstoffpräzipitate (T = 1000°C) scheinen in Form von SiO2 vorzuliegen, und es existiert ein starker Hinweis auf die Wiederauflösung der Sauerstoffpräzipitate infolge der Cr-Diffusion. Die Anwesenheit dieser Hochtemperatursauerstoffpräzipitate zeigen einen hohen Wirkungsgrad für die Getterung der Cr-Verun-reinigungen