Transient computer simulation of a CZ crystal growth process

The use of numerical simulation for improving the bulk growth process is illustrated by means of two sets of investigations. On the one hand, the rime dependent heat transfer during CZ silicon growth has been numerically simulated and compared to experiments for an industrial furnace. An excellent agreement between simulation and experiment is observed for both heater power and crucible temperature. On the other hand, 4 '', 6 '' and 8 '' CZ crystals were grown with different heat shields. It has been found that the critical pull rate V-crit, under which the oxidation induced stacking fault (OSF) ring vanishes in the wafer center, varies with the crystal diameter and the type of heat shield. A calculation of the axial temperature gradient at the solid/liquid interface for each combination reveals that the critical pull rate is proportional to this axial temperature gradient, which, in turn, is a function of the crystal diameter and heat shield. A precise law governing OSF ring formation has been established. In addition, improved processing conditions can be determined by an extensive use of simulation results

Defect engineering of Czochralski single-crystal silicon

Modern microelectronic device manufacture requires single-crystal silicon substrates of unprecedented uniformity and purity, As the device feature lengths shrink into the realm of the nanoscale, it is becoming unlikely that the traditional technique of empirical process design and optimization in both crystal growth and wafer processing will suffice for meeting the dynamically evolving specifications. These circumstances are creating more demand for a derailed understanding of the physical mechanisms that dictate the evolution of crystalline silicon microstructure and associated electronic properties. This article describes modeling efforts based on the dynamics of native point defects in silicon during crystal growth, which are aimed at developing comprehensive and robust tools for predicting microdefect distribution as a function of operating conditions. These tools are not developed independently of experimental characterization but rather are designed to take advantage of the very detailed information database available for silicon generated by decades of industrial attention. The bulk of the article is focused on two specific microdefect structures observed in Czochralski crystalline silicon, the oxidation-induced stacking fault ring (OSF-ring) and octahedral voids; the latter is a current limitation on the quality of commercial CZ silicon crystals and the subject of intense research. (C) 2000 Published by Elsevier Science S.A

Zur Wirksamkeit des Arbeitsrechts fuer die Festigung von Ordnung und Disziplin in den Betrieben und Kombinaten

ISVG 80.2210 S / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Essential features of the polytypic charoite-96 structure compared to charoite-90

Charoite, ideally (K,Sr,Ba,Mn) 15-16(Ca,Na) 32[(Si 70(O,OH) 180)](OH,F) 4•nH 2O, is a rock-forming mineral from the Murun massif in Yakutia, Sakha Republic, Siberia, Russia, where it occurs in a unique alkaline intrusion. Charoite occurs as four different polytypes, which are commonly intergrown in nanocrystalline fibres. We report the structure of charoite-96 (a = 32.11(6), b = 19.77(4), c = 7.23(1) Å, β = 95.85(9)°, V = 4565(24) Å 3, space group P2 1/m), which was solved ab initio by direct methods on the basis of 2676 unique electron diffraction reflections collected by automated diffraction tomography and refined to R 1/wR 2 = 0.34/0.37. The structure of charoite-96 is related to that of the charoite-90, which was also solved recently. Both structures are composed of three different types of dreier silicate chains running along [001] and separated by ribbons of edge-sharing Ca-and Na-centred octahedra. In the structure of charoite-96, adjacent blocks formed by three different silicate chains and stacked along the x axis, are shifted by a translation of ½ c. The shifts involve a hybrid dreier quadruple chain, [Si 17O 43] 18- and a double dreier chain, [Si 6O 17] 10-. In charoite-90 adjacent blocks are stacked without shifts. © 2011 Mineralogical Society