US 11,987,899 B2
Methods for preparing an ingot in an ingot puller apparatus and methods for selecting a side heater length for such apparatus
Maria Porrini, Merano (IT); Sergio Morelli, Merano (IT); and Mauro Diodá, Merano (IT)
Assigned to GlobalWafers Co., Ltd., Hsinchu (TW)
Filed by GlobalWafers Co., Ltd., Hsinchu (TW)
Filed on Nov. 12, 2020, as Appl. No. 17/096,516.
Prior Publication US 2022/0145490 A1, May 12, 2022
Int. Cl. C30B 15/10 (2006.01); C30B 15/00 (2006.01); C30B 15/14 (2006.01); C30B 15/20 (2006.01); C30B 15/36 (2006.01)
CPC C30B 15/10 (2013.01) [C30B 15/007 (2013.01); C30B 15/14 (2013.01); C30B 15/20 (2013.01); C30B 15/36 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method for preparing an ingot in an ingot puller apparatus, the method comprising:
providing an ingot puller apparatus for preparing ingots comprising:
a crucible for holding a melt of silicon, the crucible having a floor and a sidewall that extends from the floor, the crucible having a top, the floor comprising a curved portion;
a growth chamber for pulling a silicon ingot from the melt along a pull axis;
a lift mechanism for raising and lowering the crucible during crystal growth relative to the pull axis;
a heat shield having an opening through which the ingot passes during crystal growth, the heat shield being disposed above the crucible; and
a bottom heater disposed below the crucible floor;
selecting a length of a side heater disposed radially outward to the crucible sidewall, selecting the length of the side heater comprising:
modeling a temperature profile of the crucible in the ingot puller apparatus including the heat shield while withdrawing an ingot from the silicon melt in two or more thermal simulations, the length of the side heater being varied during the thermal simulations;
selecting the length of the side heater based on temperatures of the floor of the crucible during the two or more thermal simulations, wherein the length of the side heater is selected based on the length of the side heater during a thermal simulation in which a portion of the floor of the crucible has a temperature of about 1450° C. or less and the top of the crucible has a temperature of at least 1715° K, the crucible having a maximum temperature, the maximum temperature being within the curved portion of the crucible and being at least 1740° K;
providing a side heater disposed radially outward to the crucible sidewall, the side heater having the selected side heater length;
forming a melt of silicon in the crucible;
contacting the melt with a seed crystal; and
withdrawing an ingot from the silicon melt.