Patent ID: 9388507
Filing Date: 2016-07-12
CPC Classification: C01B,C30B

Claim Text:
1. A method for manufacturing a polycrystalline silicon ingot, comprising the steps of: providing a crucible which is made of silica; forming a silicon nitride coating layer on an inner surface of a side wall of the crucible; forming a multilayered silica coating layer on an inside bottom of the crucible by depositing a slurry layer and a stucco layer on top of each other; and unidirectionally solidifying a molten silicon in the crucible upwardly from the bottom of the crucible, wherein the slurry layer is formed by coating a slurry obtained by mixing a filler having a particle size of 10 μm or more and 50 μm or less with an aqueous dispersion of colloidal silica, the stucco layer is formed by scattering grain silica with a particle size of 0.3 mm or more and 3 mm or less, the multilayered silica coating layer is exposed at the inside bottom of the crucible, a degree of solidification is divided in the crucible into a first zone from 0 mm to X in height, a second zone from X to Y in height and a third zone of Y or higher, based on the bottom of the crucible, the height X falls in the range of 10 mm≦X<30 mm and the height Y falls in the range of 30 mm≦Y<100 mm, and a solidification rate V1 in the first zone is set in the range of 10 mm/h≦V1≦20 mm/h and a solidification rate V2 in the second zone is set in the range of 1 mm/h≦V2≦5 mm/h.