| 摘要 |
1,157,224. Crystal-pulling. GENERAL MOTORS CORP. 28 Sept., 1967 [14 Oct., 1966], No. 44110/67. Heading BIS. In the pulling of a mononcrystalline rod of silicone under a pressure of less than 3 x 10<SP>-5</SP> mm from a melt using a thin seed, the melt is protected by an apertured shield through which the rod passes and a complimentary shield on the seed holder to cover the aperture in the early stages of pulling. The apertured shield is maintained at 1,000- 1,400‹C by heat radiated from the melt. As shown, the melt is contained in a graphite crucible 22 which has a quartz liner 24, is surrounded by a cylindrical graphite resistance heater 16 and a cylindrical quartz heat reflector 18, and is covered by a shield 28 having an aperture 30 with a plurality of outwardly extending slits 42 to facilitate viewing of the solid/liquid interface. Aperture 30 is itself covered by a shield 38 on seed holder 34. In another embodiment (Fig. 3), the apertured shield is suspended close to the surface of the melt and is in the form of a composite assembly of upper and lower annular members of molybdenum, the aperture in the upper member being larger than that in the lower member. A crucible may be dispensed with by forming a molten puddle in the upper surface of a silicon ingot. |
