A CZ crystal growing furnace which has a radiative heat shield that can be raised and lowered above a crucible. The heat shield assembly includes an upper heat shield that is mounted to a furnace cover directly above the crucible. Coupled to the upper shield is a lower heat shield which can move between a first raised position and a second lower position. Attached to the seed holder of the furnace is a bar which maintains the lower heat shield in the first raised position, so that the crucible can be filled with raw silicon. After the silicon is melted, the heat shield is lowered to the second position and the bar is lifted and removed from the furnace. The lower heat shield has an outer ring which cooperates with an inner ring of the upper heat shield to suspend the lower shield in the second position. The heat shield also has a tapered wall which defines an opening that allows an ingot to be pulled from the molten silicon.
In this invention, three equally spaced and "L" shaped hooks 6B are rotatably supported on the upper peripheral wall of the body 6A of the seed holder 6 at pivots 6E. A radiation screen 7 is hung at the front ends of the hooks 6B via three engaging fixtures 6C affixed on its upper rim. The radiation screen 7 shaped like a hollow trancated cone, is used to surround the lower end of the single-crystal being lifted from the quartz crucible 3 which is disposed within the main chamber 1. According to the apparatus for manufacturing a single-crystal which can perform the descending or ascending movements of the radiation screen, the setting operation, and the lifting operation consecutively and automatically. Therefor the apparatus can enhance the productivity and avoid any problems with process automation, furthermore, it is compatible with conventional equipment.
An apparatus for fabricating single-crystal silicon easily controlling a temperature gradient based on the Czochralski (CZ) method, and more particularly preventing as-grown defects created in order to obtain high-quality single-crystal silicon. The above-mentioned apparatus includes a first thermal shield member surrounding the pulling single-crystal silicon and a second thermal shield member inside the first thermal shield member, surrounding the pulling single-crystal silicon. The second thermal shield member is fixed on the first thermal shield member by a support located on the external surface of the second thermal shield member and connected to the first thermal shield member. The surroundings of a solid-liquid interface are extremely cooled by using the first thermal shield member, thereby a stable shape of the single-crystal silicon is formed. The temperature gradient of the temperature region of 1000.degree. C..about.1200.degree. C. where the single-crystal silicon passes is decreased by using the second thermal shield member so as to reduce the crystal defect density, thereby obtaining single-crystal silicon having a stronger oxide film voltage breakdown characteristic. If the support length is changed, the second thermal shield member can be adjusted in the upper or lower direction in order to make the expected portion of single-crystal silicon cool slowly.
An apparatus and a method for fabricating a single-crystal semiconductor by means of CZ method are provided for improving the quality control through the modification of thermal cycle of a pulled single-crystal semiconductor. The apparatus includes a ring after heater which is capable of elevation. The method decreases a temperature gradient to smaller than 20.degree. C./cm, and preferably under 15.degree. C./cm, when the pulled single-crystal semiconductor is cooled from 1200.degree. C. to 1000.degree. C. The after heater therefore heats the single-crystal semiconductor where there is a temperature of 100-300.degree. C. lower than the range of 1200-1000.degree. C. A thermal shelter is provided to retain a temperature gradient of larger than 20.degree. C./cm when the single-crystal semiconductor is within the temperature range between the melting point and 1250.degree. C. The after heater and the shelter can be raised to an upper portion when polysilicon blocks are charged and a twisting step is carried out.
An apparatus and a method for fabricating a single-crystal semiconductor by means of a CZ method are provided for improving the quality through modification of the thermal cycle of a pulled single-crystal semiconductor. The apparatus includes a ring-shaped after heater which is capable of elevation. The method decreases the temperature gradient to smaller than 20.degree. C./cm, and preferably under 15.degree. C./cm, when the pulled single-crystal semiconductor is cooled from 1200.degree. C. to 1000.degree. C. The after heater therefore heats the single-crystal semiconductor where there is a temperature of 100.degree.-300.degree. C. lower than the range of 1200.degree.-1000.degree. C. A thermal baffle (or shield) is provided to retain a temperature gradient of larger than 20.degree. C./cm when the single-crystal semiconductor is within the temperature range between the melting point and 1250.degree. C. The after heater and the baffle (or shield) can be raised to an upper portion when polysilicon blocks are charged and a twisting step is carried out.
An apparatus and method for growing large diameter silicon crystals using the Czochralski (Cz) method, wherein the neck section of the crystal is significantly strengthened to eliminate the risk of breakage in the neck section, by providing a heat shield assembly which is located adjacent to the neck section and ascends in conjunction therewith to force the cooling gas directly onto the neck section of the silicon ingot.
