Abstract: A method for manufacturing a polysilicon ingot includes: (a) providing molten silicon in a container; (b) maintaining a surface temperature of the molten silicon higher than its melting point while decreasing the temperature of a base portion of the container to a temperature (T1) lower than the melting point at a rate of at least 2.6° C./min; (c) increasing the temperature of the base portion to a temperature (T2) lower than the melting point; (d) maintaining the surface temperature of the molten silicon higher than the melting point while decreasing and then increasing the temperature of the base portion to a temperature lower than the melting point of silicon; and (e) reducing the temperature of the molten silicon to form the polysilicon ingot.