The invention discloses a multi-stage side heater in a
vertical gradient freezing
crystal growing furnace. The multi-stage side heater comprises a
graphite sleeve, and an upper heater and a lower heater positioned in the
graphite sleeve, wherein the upper heater in the
graphite sleeve is connected with a
graphite electrode fixed on an upper furnace cover plate, and is connected with the graphite sleeve through
boron nitride; or the upper heater is supported by a graphite block, and the graphite sleeve is connected with an
electrode fixed on the upper furnace cover plate; the lower heater is arranged in the graphite sleeve and is supported by a graphite block; and the graphite sleeve is connected with the
electrode fixed on the upper furnace cover plate, and is fixed on the upper furnace cover plate through a screw. The invention has the advantages that: a suspended side
heating system can entirely move upwards together with a furnace cover, and is entirely detached, and an insulating layer outside the
heating system is not needed to be detached, so equipment maintenance, material loading and material taking are greatly facilitated; and a long
plate electrode is adopted, a complete graphite cylinder is formed outside the side
heating system, and the graphite cylinder can absorb, reradiate and reflect heat of the heater, so the heat utilization ratio is improved, and a thermal field has higher symmetry and stability.