Abstract: The invention relates to a method for assembling planar workpieces, whereby a connection, whose adhesiveness and brittleness is temperature-dependent, is made by means of a cement between the planar workpiece and a support plate. The method is characterised in that connected are only partially covered by the cement after the workpiece has been placed on the support plate.

Abstract: A process for removing contaminants, particularly dopant, from halosilane-containing carrier gases, such as those which are produced in the production of high-purity silicon. The process of the invention is perferably carried out with aid of zeolites which has a low proportion of aluminum and are used in the anhydrous state by bringing the zeolites into contact with the carrier gases. Zeolites, after use, can be regenerated and re-used by increasing the temperature and/or decreasing the pressure of the procedure.

Abstract: A process and apparatus for etching semiconductor surfaces, in particular, ilicon, with a mixture containing nitrogen-oxygen based compounds as oxidizing compounds, hydrofluoric acid as the component which dissolves the oxidation product, and sulfuric acid, optionally with phosphoric acid added, as a carrier medium. This mixture makes it possible to design the process as a cyclic process in which oxygen supplied to the system ultimately effects an oxidation of the material to be etched, and the product of its oxidation is removed from the circuit. The process is noteworthy for its low usage of reagents and because it is not harmful to the environment.

Abstract: The liquid or gaseous substances, such as hydrogen or trichlorosilane, enntered in the gas-phase deposition of silicon may contain n-type doping impurities which can be removed by adduct formation with silicon, titanium or tin halides. The impurities can be liberated from the adducts by thermal treatment and finally removed. The halides left behind are capable of again forming adducts and are again used to remove the impurities. The process can consequently be operated cyclically and is remarkable for the low quantity of chemicals required and for its ecological harmlessness.

Abstract: A process for the chemical vapor deposition of oxidic particles by oxidat of halides or halide mixtures wherein dinitrogen monoxide is used as the oxidizing agent. The reaction is carried out at comparatively low temperatures of between 900.degree. and 1150.degree. C., but results in high yields.