Wacker-Chemitronic Gesellschaft Fur Elektronik-Grundstoffe Mbh

Walter Berger

Dieter Seifert

Dieter Regler

Alfred Moritz

Bernd Mittelbach

Volker Ofenmacher

Werner Bauer

Christian Hofstetter

August Freudlsperger

A process and an apparatus for carrying out the process provides for the accurate and simple control of the melt level when pulling single crystals according to the Czochralski process. The process comprises disposing a mechanical reference mark above the melt in such a way that it causes a reflection from the melt surface. An image of the metal surface is then recorded, and with the aid of the recorded image the distance of the mechanical reference mark from the melt surface is determined. An actual signal proportional to this distance is then generated and is compared with a set point signal, and the melt level is changed as a function of any difference observed.

Process and apparatus for controlling the melt level while pulling

Apparatus for machining workpieces by abrasion by means of an oscillating ltiple-blade tool, which is moved across the workpiece. The moved masses define an oscillatory system, as a result of which the energy can be stored in the reversal ranges by a buffer system. This apparatus, especially when designed as a lap-cutting machine for cutting semiconductor rods, is preferably driven by the oscillation of the masses to be moved, and is driven in the resonance range. The tool carriages are buffer loaded at each end and are oscillated at or near the natural resonance frequency of the moving masses.

Apparatus for machining workpieces by abrasion

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Simbach am Inn, Germany

Walter Berger