A silicon-ingot-growing furnace using electron-bombardment heating

A new type of furnace for preparing single-crystal ingots of silicon by the Czochralski technique is described. The ingot can be conveniently pulled from a melt resting on the parent solid material which in turn rests on a cooled metal hearth. The charge is heated by four focused and deflected electron beams, and a feature of the gun design is a movable cathode for controlling the magnitude of the electron current. Infra-red absorption measurements on ingots prepared by this technique indicate that the bulk oxygen content is much less than in ingots prepared from crucible-held melts.