The invention belongs to the technical field of polysilicon purification, in particular to a method for removing impurities through
directional solidification by adopting the technology of
electron beam inducing. The method comprises the following steps of selecting, washing and
drying metallurgical grade polysilicon with
high aluminum content and
high calcium content, placing the polysilicon in a
crucible, vacuumizing the polysilicon, starting an
electron gun to bombard the polysilicon at a beam flow of 400-700 mA till the polysilicon is totally dissolved to form into a
molten pool, and continuously
smelting the
molten pool for 30-60 min; and then reducing the beam flow of the
electron beam by adopting a way of logarithmic beam drop, after the beam flow of the electron beam is reduced to 100-150 mA, stopping droping the beam, the melt slowly freezes to form into an
ingot, closing the beam flow to obtain a polysilicon
ingot with low aluminum and
low calcium contents. According to the method provided by the invention, as the
evaporation effect and
segregation effect of impurities in the
silicon are fully utilized, the complementary advantages of two
impurity removing ways of electron beam
smelting evaporation and
directional solidification can be realized; the aluminum and
calcium impurities can be ensured to be removed after one step of
smelting so as to meet the performance requirements of a
solar cell; the process section is reduced, the
energy consumption is reduced, and the method can be in favor of the large-scale promotion and application.