The invention relates to a
single crystal furnace with multiple safety protection. The
single crystal furnace comprises a lower furnace chamber, a furnace cover, an isolating valve, an auxiliary chamber, an upper transmission mechanism, a water-cooled hot screen installed in the lower furnace chamber, a flow guide cylinder, a flow guide cylinder lifting device, a
quartz crucible and a lower transmission mechanism, and further comprises a contact liquid
contact system, a weighing
system, a CCD
monitoring system, and an isolating valve
safety monitoring system. The contact liquid contact systemis capable of detecting abnormal operation of an excessive high
silicon liquid level and warning. The
crucible is automatically descended by the
system in a high speed, and the water-cooled hot screenis lifted at the same time, so that a
water leakage accident is avoided. The weighing system is capable of uploading and detecting a weight of a pulled
silicon rod in real time in a
crystal pulling process, when the weight of the
silicon rod is suddenly increased or suddenly decreased in an instant moment, the system stops operating, and an alarm is sent. The CCD
monitoring system is capable of monitoring abnormal change of a liquid level position in the
quartz crucible and warning. The isolating valve
safety monitoring system is capable of monitoring a position of the
crystal rod, and improving opening-closing safety protection of a valve plate.