Determination of mass/time ratios for buffer members used during growth of single crystal silicon ingots

A method for determining a threshold ratio of M/T for growing a single crystal silicon ingot in a continuous Czochralski process that includes forming a melt of silicon in a crucible assembly, adding a batch of buffer members to the melt with the batch having a mass M, contacting a surface of the melt with a seed crystal, withdrawing a single crystal silicon ingot from the melt, the single crystal silicon ingot comprising a main body, there being a time T between adding the batch of buffer members to the melt and start of growth of the main body, and adding solid polycrystalline silicon feedstock to the crucible assembly while withdrawing the single crystal silicon ingot to replenish the melt, the method comprising:

• growing a plurality of single crystal silicon ingots with at least two of the ingots being grown with different ratios of M/T;
• measuring a defect count in one or more wafers sliced from the plurality of single crystal silicon ingots;
• and
• determining the ratio of M/T for single crystal silicon ingots from which wafers were sliced having a defect count below a threshold defect count.