A chamber is provided which includes baffles, plates, and support members situated around a centrally located heater and crucible to define a hot zone in the lower half of the chamber where gas currents are quickly heated and thence sent to the upper half of the chamber. As a result, the motion of these currents around the hot zone is reduced, which reduction permits thermal gradients to be maintained around the crucible for controlling crystal growth therein. A resistance heater provides heat for a crystal melt contained inside the crucible.
A heating resistor of a single crystal manufacturing apparatus, which comprises a cylindrical side wall portion surrounding a melting pot, a bottom portion supporting the side wall portion, and a plurality of slits formed in the side wall portion and bottom portion, wherein said bottom portion has a maximum thickness which is not greater than that of said side wall portion, and said bottom portion has a minimum inner diameter which falls within a range of 20 to 80% of an inner diameter of a lowermost portion of said side wall portion.
A picket or zig-zag type heater for use in high temperature furnaces, such as are used for crystal growing for example, is constructed from a plurality of like graphite cylindrical shell segments assembled into a cylindrical shell having uniform resistance heating characteristics by graphite connector elements which also function to couple the electric current source to the heater.
An electrical resistance heater for use in a crystal puller used for growing monocrystalline silicon ingots according to the Czochralski method comprises a heating element sized and shaped for disposition in the housing of the crystal puller around the crucible for applying heat to the crucible and silicon therein. The heating element includes heating segments connected together in an electric circuit. The segments have upper and lower sections and are arranged relative to each other so that when disposed around the crucible containing molten silicon the upper sections are disposed generally above a horizontal plane including the surface of the molten silicon and the lower sections are disposed generally below the horizontal plane. The upper sections are constructed to generate more heating power than the lower sections thereby to reduce a temperature gradient between the molten silicon at its surface and the ingot just above the surface of the molten silicon. The upper sections have a thickness substantially equal to the thickness of the lower sections and have a width substantially less than the width of the lower sections. The cross-sectional area of the upper sections is everywhere less than the cross-sectional area of the lower sections.
A zig-zag picket graphite heater for use in high temperature furnaces of the type used for crystal growing, for example, utilizes a plurality of discrete graphite arcuate shell segments having vertically extending slots alternating from the upper and lower ends thereof. The edge pickets are adjacent slots which extend upwardly from the lower end of the segment and have extensions projecting below the other pickets so as to provide pads below the level of the slots. Graphite connectors span the adjacent pads of adjacent arcuate segments and certain of the connectors are also connected to electrical power supply terminals.
A zig-zag picket type graphite heater for use in high temperature furnaces such as are used for crystal growing, for example, is constructed by forming and zig-zag slotting a cylindrical shell-like element. The cylindrical element is then cut into a plurality of like, discrete segments by extending selected ones of the slots through the entire length of the element. Graphite connector elements are then secured between the segments to connect the segments, and also function as connectors to an electric current supply line.
