Patent ID: 8012258

Claim:
An apparatus for monitoring a liquid surface position of a melt in a crucible in the process of silicon single crystal growth by the Czochralski method using a melt surface position at the time of seeding as a reference position, which apparatus comprises: means for observing the surface position of said melt, means for observing the position of said crucible, means for memorizing the shape of the silicon single crystal pulled up from the surface of said melt, means for calculating an estimated melt surface position based on the melt surface position as observed, the position of the crucible as observed and the shape of the silicon single crystal as memorized, and means for transmitting information about the estimated melt surface position to a sequence circuit at an interval of control period to control the raising or lowering of the crucible, wherein, when said estimated melt surface position passes a preset upper limit position, the crucible is stopped from raising.