Das Projekt "Entwicklung eines On-line Partikeldetektors" wird vom Umweltbundesamt gefördert und von Universität Duisburg, Fachbereich 9 Elektrotechnik, Fachgebiet Prozess- und Aerosolmesstechnik durchgeführt. In semiconductor technology clean process gases must be provided to manufacture large scale integrated chips. To prevent micro contamination of wafers, the process gases must be controlled by on-line detection of suspended particles. In this project the on-line particle detection is realized by means of optical method. Due to the low particle concentration, the entire cross section of the gas pipe has to be controlled. Thus it is necessary to install an illuminating plane of over 32 mm2 perpendicularly to gas flow. In clean gases paricles down to 0,1 my m must be detected. In this size range molecule noise leads to False-Count-Rate. To reduce the F.C.R. an additional illuminating plane is arranged parallel to the original one, and the F.C.R. is decreased via anew Pipeline-Cross-Correlation-Function, which is developed in this project. Using this P.C.C.F. method the influence of molecule noise on particle detection can be strongly reduced, and detection becomes possible without any dead time. To create the illuminatingplanes non-imaging optical elements are used, where beam bend is caused by reflection and diffraction exclusively. Applying computer simulation, the optical characteristics of those non-imaging optics are investigated, and it is shown that the scattered light intensity is nearly independent on local position of detected particles in the plane. The application of the non-imaging optics leads to high precision combined with low manufacturing costs. The results of optical simulation show that the pre-condition to detected particles with non-condition to detected particles with non-imaging optics in clean process gases in fulfilled, i.e. the entire gas flow is controlled, and the low detection limit is expanded down to 0,1 micron and local dependence of detector is smaller than 4 percent within measuring volume 6,4 mm x 6,4 mm. The algorithm of P.C.C.F. is based on classical cross-correlation. The difference between them is that output result from P.C.C.F. is a function of real time, t, but not a function of delaying time, t, which corresponds to the time difference between the two signals. Therefore, it is possible to set P.C.C.F. in on-line measurement. To examine the efficiency of P.C.C.F., a particle signal mixed with two acquired noise are simulated on computer. The results of simulation show that, in output process of P.C.C.F., the noise is reduced and the level of particle signal becomes higher. The signal-noise reatio is improved from one to four.
Das Projekt "Entwicklung eines Partikelabscheidungsmeters" wird vom Umweltbundesamt gefördert und von Universität Duisburg, Fachbereich 9 Elektrotechnik, Fachgebiet Prozess- und Aerosolmesstechnik durchgeführt. During the last ten years increasingly stringent requirements have been set for the cleanliness of the production environment for contamination sensitive products. This is not only the case in the microelectronics industry, but also in the field of biotechnology and in the optical industry. Not only the monitoring of airborne particles in the production environment is necessary for the correct manufacture of the products, but particularly the analysis of the deposited particles on the surfaces. Measurement technologies detecting the particle scattered light lead to fast non-contact particle detection and characterisation. A measuring device was developed making it possible to detect in situ particles on a surface. The most important innovation is the use of a transparent material as deposition surface, which makes it possible to illuminate the particles and to detect the scattered light by the particles from the back of the surface. The measured parameter are the number of particles on the surface, the differences between the number of particles per area in specific time intervals (particle flux density) and the particle diameter. The principle verification of the measuring device was carried out with deposited fibres of 4 my m and 12 my m in diameter and with a metalized grid on a glass plate. The measurement results show a definite image of the objects deposited on the surface. To verify if single particles can also be detected from the measuring device Latex particles with diameters from 1,4 my m were deposited on a glass plate. To assure that the detected scattered light signals are in fact from the Latex particles and not from other contaminating objects on the surface the glass plate was additionally analysed with a light microscope incombination with an image processing system. By the comparison of the measurement results with the images of the microscope it was verified that the detected scattered light signals in fact belong to the deposited Latex particles. The measurement data were compared with the calculated scattered light signals for different incident and detecting angles. They showed good agreement.
Das Projekt "Teil III: Untersuchungen zur Auswirkung von wasserseitigen Massnahmen auf die Entwicklung von Schaeden durch Lochkorrosion in Kupferleitungen" wird vom Umweltbundesamt gefördert und von Universität Duisburg, Rheinisch-Westfälisches Institut für Wasserforschung durchgeführt. Beim Werkstoff Kupfer zur Verteilung von Trinkwasser in Hausinstallationen sind zwei Korrosionsarten von Bedeutung: Lochkorrosion und Flaechenkorrosion. Die der Bevoelkerung durch Lochkorrosion an Kupferrohren entstehenden Schaeden sind hoch, aber nicht bezifferbar, weil sie nicht systematisch erfasst werden. Die Tatsache jedoch, dass die Kupferindustrie ab 1997 bei der Verbindung von Kupferleitungen das Hartloeten verboten hat, deutet an, dass die Schaeden durch Lochkorrosion in Nachbarschaft von Hartloetverbindungen enorm sind. Trinkwaesser koennen z.T. als die Lochkorrosion 'beguenstigend' oder 'nicht beguenstigend' charakterisiert werden, jedoch gibt es bis heute keine gesicherten Erkenntnisse darueber, welche Wasserinhaltsstoffe in welchem Umfang die Entwicklung von Lochkorrosion beeinflussen. Es gibt jedoch Hinweise darauf, dass Inhibitoren das Tiefenwachstum von Lochfrassstellen verringern bzw. unterbinden. In dem Forschungsprojekt soll erstmals systematisch die Frage beantwortet werden: Wie beeinflussen Inhibitoren das Tiefenwachstum von gezielt initiierten Lochfrassstellen? Fuer die Ermittlung der Geschwindigkeit des Lochtiefenwachstums werden optische und neuartige statistische Methoden eingesetzt.