US 11,987,901 B2
Methods for forming a silicon substrate with reduced grown-in nuclei for epitaxial defects and methods for forming an epitaxial wafer
Pietro Valcozzena, Agordo (IT); Maria Porrini, Merano (IT); and Januscia Duchini, Marlengo (IT)
Assigned to GlobalWafers Co., Ltd., Hsinchu (TW)
Filed by GlobalWafers Co., Ltd., Hsinchu (TW)
Filed on Apr. 1, 2022, as Appl. No. 17/711,691.
Application 17/711,691 is a division of application No. 17/125,590, filed on Dec. 17, 2020.
Claims priority of provisional application 63/112,424, filed on Nov. 11, 2020.
Prior Publication US 2022/0220636 A1, Jul. 14, 2022
Int. Cl. C30B 29/06 (2006.01); C30B 15/00 (2006.01); C30B 15/04 (2006.01); C30B 15/14 (2006.01); C30B 15/20 (2006.01); C30B 29/66 (2006.01); C30B 25/10 (2006.01); C30B 25/20 (2006.01)
CPC C30B 29/06 (2013.01) [C30B 15/007 (2013.01); C30B 15/04 (2013.01); C30B 15/14 (2013.01); C30B 15/203 (2013.01); C30B 29/66 (2013.01); C30B 25/10 (2013.01); C30B 25/20 (2013.01)] 16 Claims
OG exemplary drawing
 
1. A method for forming a silicon substrate with reduced grown-in nuclei for epitaxial defects, the silicon substrate being boron doped, the method comprising:
adding an initial charge of polycrystalline silicon to a crucible;
heating the crucible comprising the initial charge of polycrystalline silicon to cause a silicon melt to form in the crucible;
adding boron to the crucible to produce a doped silicon melt;
contacting a silicon seed crystal with the doped silicon melt;
withdrawing the silicon seed crystal to grow a single crystal silicon ingot, the ingot having a constant diameter portion, wherein a segment of the constant diameter portion of the ingot has a boron concentration from 2.8×1018 atoms/cm3 to 5.4×1018 atoms/cm3;
controlling (i) a growth velocity, v, and/or (ii) an axial temperature gradient, G, during the growth of the segment such that v/G is less than 0.20 mm2/(min*K) and interstitials are the dominant intrinsic point defect in the segment;
cooling the segment of the constant diameter portion of the ingot from its solidification temperature to 950° C. or less, wherein the dwell time the segment of the constant diameter portion of the ingot is in the temperature range from 1150° C. to 950° C. is less than 160 minutes; and
slicing the substrate from the single crystal silicon ingot.