Patent ID: 8733425

Claim:
A casting device for producing semiconductor material foil, said casting device comprising a casting frame and a substrate band, the casting frame being arranged for holding a molten semiconductor material and comprising sidewalls of which an exit sidewall is located at an output position for the semiconductor material foil, the exit side wall being provided with an exit slit, wherein the casting device further comprises a local force exerting means to exert at the location of the exit slit a local relatively enlarged external force on the molten semiconductor material to enlarge locally an outer pressure on the molten semiconductor material at the exit slit as compared to a working pressure surrounding the casting frame, thereby reducing drag-out of the molten semiconductor material; wherein the force exerting means comprises an overpressure device; the overpressure device being arranged at the exit sidewall of the casting device and is adapted for producing at the location of the exit slit an overpressure relative to the outer pressure; and wherein the overpressure device comprises an inlet for pressurized gas, a pressure leveling chamber, and an overpressure chamber; the inlet being connected with an entrance of the pressure leveling chamber, an exit of the pressure leveling chamber being in communication with the overpressure chamber, the overpressure chamber being located at the exit slit of the casting frame.