The invention relates to a thermal field structure of a polysilicon
ingot casting furnace, which comprises a furnace body, a thermal-insulation cage body and a
crucible, wherein the thermal-insulation cage body is arranged inside the furnace body, the
crucible is arranged inside the thermal-insulation cage body, and the thermal-insulation cage body is a sealed thermal field chamber formed by an upper thermal-insulation body, a lower thermal-insulation body and a thermal-insulation baseplate; the upper thermal-insulation body is fixed on the furnace body; the bottom of the lower thermal-insulation body is placed on the thermal-insulation baseplate, and the lower thermal-insulation body can slide up and down relative to the upper thermal-insulation body through a lifting mechanism; the
crucible is placed on a heat exchange platform in a supporting structure; and the thermal-insulation baseplate is placed on supporting columns of the supporting structure for fixation. In the invention, when a
silicon material is heated, melted and thermally preserved for a period of time, in a lifted process of the lower thermal-insulation body, a vertical
temperature gradient field is formed on a
crystallization face of the
silicon material due to the vertical
temperature difference inside the thermal field chamber, and the crystallographic orientation of the
silicon material can be realized by controlling heat dissipating and heating, so that the quality of a polysilicon cast
ingot is improved. Meanwhile, the
process time is shortened, the
energy consumption is decreased and the unit productivity is improved.