Design of hard-shaft Czochralski growth furnace based on motion separation sealing for large-size monocrystalline silicon growth

Abstract

Czochralski growth process has been used for the fabrication of monocrystalline silicon, while the furnace vibration is always observed and seriously affect the quality of silicon ingots, especially for large-size monocrystalline silicon. This paper studied the structural design of hard-shaft monocrystal furnace by separating the axial and circumferential motions between the furnace chamber, the vibration caused by crystal rotation can be greatly reduced. With more stable pulling speed control, the furnace can achieve a uniform thermal field and temperature distribution on the growth interface for monocrystalline silicon growth with high quality. Then, numerical model was established to analyze the thermal field of the growth chamber and especially its influence on furnace vibrations. The vibration tests were conducted and results showed that the vibration acceleration of the growth furnace based on our designed motion separation sealing structure is extremely low. After that, 12-inch monocrystalline silicon growth experiments were conducted and the sliced silicon wafer was characterized. Characterization results showed that the oxygen content of the silicon wafer is low with the value of 7.5 × 10¹⁷ /cm³, the average resistivity is about 12.97 Ω·mm with a radial resistance variation of 3.79 %. The obtained results indicated that our designed hard-shaft monocrystal furnace could be used for high-quality large-size silicon growth production.