Patent ID: 8529695
Filing Date: 2013-09-10
Classification: C30B

Abstract:
1. A silicon wafer manufacturing method comprising; a first cleaning process of cleaning block-shaped or grain-shaped polycrystalline silicon with a dissolved ozone aqueous solution, a second cleaning process of cleaning the polycrystalline silicon cleaned in the first cleaning process with fluoric acid or mixed acid of fluoric acid and nitric acid, a process of rinsing the polycrystalline silicon cleaned in the second cleaning process with ultra pure water, a process of melting the rinsed polycrystalline silicon and pulling a single crystal silicon ingot from the molten silicon liquid at a solidification ratio of 0.9 or less, a process of making the pulled single crystal silicon ingot into block-shaped or grain-shaped single crystal silicon, a third cleaning process of cleaning the block-shaped or grain-shaped single crystal silicon with a dissolved ozone aqueous solution, a fourth cleaning process of cleaning the single crystal silicon cleaned in the third cleaning process with fluoric acid or mixed acid of fluoric acid and nitric acid, a process of rinsing the single crystal silicon cleaned in the fourth cleaning process with ultra pure water, a process of remelting the rinsed single crystal silicon and pulling again a single crystal silicon ingot from this molten silicon liquid at a solidification of 0.9 or less as controlling the pulling speed and the temperature gradient so that V/G is a ratio being not smaller than (V/G) a process of forming a silicon wafer out of said single crystal silicon ingot, wherein V means a speed (mm/minute) of pulling an ingot from a molten silicon liquid, G means a temperature gradient (° C./mm) in the interface portion between the ingot and the molten silicon liquid, (V/G)