Abstract: A double-walled quartz-glass tube for semiconductor-technology processes. The overall structure comprises an inner tube surrounded by a coaxially positioned outer tube. An annular space is left between them. The ends of the tubes that face in the same direction each have a closure. A processing-gas supply connection is mounted on the inner-tube closure and extends tight through the outer-tube closure. The outer tube is sealed tight at the other end against the outside of the inner tube. The outer tube has connections for supplying and removing a scrubbing gas. The object is to prevent the occurrence of defects due to differences in the extent that the two tubes expand to as the result of the heat generated during processing. The inner tube has a diameter of at least 150 mm. At least one of the closures is essentially flat. The axis of the processing-gas supply connection is in alignment with the axis of the inner tube.

Abstract: A tray made of silica glass or ceramic material with a seating component made out of U-shaped lengths, for disk-shaped elements and especially for round wafers, whereby the elements are secured in the seating component by means of slots. To provide a tray that is shaped in such a way as to provide easy access, is highly stable, and is designed to accept a wide range of wafer sizes, the seating component is in the form of two U sections, each with a base and two sides that are spaced by means of transverse tubes in such a way that the bases of the sections slope toward each other, the slots in the sides being deep enough for the upright elements to rest at points or along lines on the bases.

Abstract: A method is described for the production of porous bodies from vitreous silica without the use of tools. Vitreous silica wool and/or threads are wound in layers on a form. After the coil has attained a certain minimum thickness, the threads of each succeeding layer are permanently bonded by heating the threads of the preceding layer at the points where the threads cross. The form is removed, and then the threads on the inside of the body are bonded together.The bodies are used for the production of high-purity blocks of silicon for solar cells.