Abstract: Silicon single crystals are pulled from a melt in a crucible, the single crystal surrounded by a heat shield, the lower end of which is a distance h from the melt surface, wherein gas flows downward between the single crystal and the heat shield, outward between the lower end of the heat shield and the melt, and then upward in the region outside the heat shield. The internal diameter of the heat shield at its lower end is 55 mm or more than the diameter of the single crystal, and the radial width of the heat shield at its lower end is not more than 20% of the diameter of the single crystal. Highly doped single crystals pulled accordingly have a void concentration ?50 m?3.

Abstract: Silicon single crystals are pulled from a melt in a crucible, the single crystal surrounded by a heat shield, the lower end of which is a distance h from the melt surface, wherein gas flows downward between the single crystal and the heat shield, outward between the lower end of the heat shield and the melt, and then upward in the region outside the heat shield. The internal diameter of the heat shield at its lower end is 55 mm or more than the diameter of the single crystal, and the radial width of the heat shield at its lower end is not more than 20% of the diameter of the single crystal. Highly doped single crystals pulled accordingly have a void concentration ?50 m?3.

Abstract: The invention relates to a process for producing highly doped semiconductor wafers, in which at least two dopants which are electrically active and belong to the same group of the periodic system of the elements are used for the doping. The invention also relates to a semiconductor wafer which is free of dislocations and is doped with at least two electrically active dopants which belong to the same group of the periodic system of the elements.

Abstract: Process for producing a silicon single crystal with controlled carbon content, polycrystalline silicon being melted in a crucible to form a silicon melt, a stream of inert gas with a flow rate being directed onto the melting polycrystalline silicon, and the single crystal is pulled from the melt in accordance with the Czochralski method, wherein the flow rate of the inert gas stream is controlled in order to set a concentration of carbon in the melt.

Abstract: A process for producing a doped silicon single crystal, comprising after-doping the melt during the pulling process with a quantity of volatile dopant ?N(t), calculated according to the equation ?N(t)=N0?N(t)=N0·(1?e??a·t) or according to the approximation equation ?N(t)=N0·?a·t where ?a is an evaporation coefficient which describes process-specific evaporation behavior of the foreign substance and which is obtained after a resistance profile R(t) of a further single crystal has been measured and calculated according to the equation R(t)=R0·e?a·t, where R0 is a starting resistivity and the further single crystal is pulled under the same process conditions without being after-doped with the foreign substance.

Abstract: The invention relates to a process for producing highly doped semiconductor wafers, in which at least two dopants which are electrically active and belong to the same group of the periodic system of the elements are used for the doping. The invention also relates to a semiconductor wafer which is free of dislocations and is doped with at least two electrically active dopants which belong to the same group of the periodic system of the elements.

Abstract: A process for producing a silicon single crystal which is doped with highly volatile foreign substance by pulling the single crystal from a melt which is held under predetermined process conditions in a crucible. A quantity of the foreign substance N0 is added in order to achieve a desired resistance of the melt, and the melt, after a time t, is after-doped at least once with a quantity &Dgr;N(t) of the foreign substance, in order to compensate for losses caused by the foreign substance evaporating out of the melt.

Abstract: A method for doping a melt with a dopant has the melt being provided in a crucible. The dopant is introduced into a vessel and the vessel is immersed in the melt, the dopant being transferred into the melt through an opening which forms in the vessel. There is also an apparatus which comprises a vessel containing the dopant and a device which is connected to the vessel, for lowering the vessel into a melt and for lifting the vessel out of the melt, the vessel being provided with an opening which is blocked by a closure piece which is of the same type of material as the melt and melts when it is brought into contact with the melt.

Abstract: A process for producing a highly doped silicon single crystal by pulling the single crystal from a molten material which contains dopant and is held in a rotating crucible. Growth fluctuations during the pulling of the single crystal are limited to an amount of −0.3 mm/min to 0.3 mm/min.

Abstract: A single-crystal rod, obtained using CZ crucible pulling, has a crystal cone and a cylindrical single-crystal rod, and the crystal cone has an apex angle of 30° to 90°. There is also a process for producing dislocation-free single-crystal rods using CZ crucible pulling in which a seed crystal is immersed in a melt and is pulled out again, and a cone with an apex angle of from 30° to 90° is pulled.

Abstract: A single-crystal rod, obtained using CZ crucible pulling, has a crystal cone and a cylindrical single-crystal rod, and the crystal cone has an apex angle of 30° to 90°. There is also a process for producing dislocation-free single-crystal rods using CZ crucible pulling in which a seed crystal is immersed in a melt and is pulled out again, and a cone with an apex angle of from 30° to 90° is pulled.

Abstract: A grinding machine has a swivel head (1) with at least one plunge-grinding wheel (2), a cup wheel (3) and a measuring gauge (7) for measuring the diameter and the length of the workpiece.

Abstract: A method for doping a melt with a dopant has the melt being provided in a crucible. The dopant is introduced into a vessel and the vessel is immersed in the melt, the dopant being transferred into the melt through an opening which forms in the vessel. There is also an apparatus which comprises a vessel containing the dopant and a device which is connected to the vessel, for lowering the vessel into a melt and for lifting the vessel out of the melt, the vessel being provided with an opening which is blocked by a closure piece which is of the same type of material as the melt and melts when it is brought into contact with the melt.