Axial positioning of magnetic poles while producing a silicon ingot

A method for producing a silicon ingot, the method comprising:

• melting polycrystalline silicon in a crucible enclosed in a growth chamber of an ingot puller apparatus to form a melt, the melt having a melt free surface;
• generating a horizontal magnetic field within the growth chamber;
• contacting a seed crystal with the melt;
• withdrawing the seed crystal from the melt to form the silicon ingot;
• raising the crucible to maintain the melt free surface at the same position relative to the ingot puller apparatus;
• and
• regulating a position of a maximum gauss plane during formation of a constant diameter portion of the silicon ingot in at least two stages of ingot growth, the at least two stages comprising:
• a first stage corresponding to formation of the silicon ingot from a beginning of formation of the constant diameter portion of the silicon ingot up to an intermediate ingot length;
• and
• a second stage corresponding to formation of the silicon ingot from at least the intermediate ingot length to a total length of the constant diameter portion, the crucible being raised during the first and second stages of ingot growth;
• and
• wherein regulating the position of the maximum gauss plane comprises maintaining the position of the maximum gauss plane in the second stage at a position lower than the position of the maximum gauss plane during the first stage, the position of the maximum gauss plane being maintained at a position at least 100 mm below the melt free surface during the second stage.