Methods for growing a nitrogen doped single crystal silicon ingot using continuous Czochralski method

A method of preparing a single crystal silicon ingot by the Continuous Czochralski method, the method comprising:

• adding an initial charge of polycrystalline silicon to a crucible, the initial charge further comprising a source of nitrogen;
• heating the crucible comprising the initial charge of polycrystalline silicon and the source of nitrogen to cause a silicon melt to form in the crucible, the silicon melt comprising an initial volume of molten silicon and having an initial melt elevation level;
• contacting a silicon seed crystal with a silicon melt;
• withdrawing the silicon seed crystal to grow a neck portion, wherein the silicon seed crystal is withdrawn at a neck portion pull rate during growth of the neck portion, and further wherein the neck portion has a neck portion nitrogen concentration of at least about 1×1013 atoms/cm3, wherein the neck portion nitrogen concentration varies by no more than 20% above and no less than 20% below an average neck portion nitrogen concentration;
• withdrawing the silicon seed crystal to grow an outwardly flaring seed-cone adjacent the neck portion, wherein the silicon seed crystal is withdrawn at a seed-cone pull rate during growth of the outwardly flaring seed-cone, and further wherein the outwardly flaring seed-cone has an outwardly flaring seed-cone nitrogen concentration of at least about 1×1013 atoms/cm3, wherein the outwardly flaring seed-cone nitrogen concentration varies by no more than 20% above and no less than 20% below an average outwardly flaring seed-cone nitrogen concentration;
• and
• withdrawing the silicon seed crystal to grow a main body of the single crystal silicon ingot adjacent the outwardly flaring seed-cone, wherein the silicon melt comprises a volume of molten silicon and a melt elevation level during growth of the main body of the single crystal silicon ingot, and further wherein the main body of the single crystal silicon has a main body nitrogen concentration of at least about 1×1013 atoms/cm3, wherein the main body of the single crystal silicon ingot is at least about 1000 millimeters long, and further wherein the main body nitrogen concentration varies by no more than 20% above and no less than 20% below an average main body nitrogen concentration over at least 40% of axial length of the main body of the single crystal silicon ingot;
• wherein the main body of the single crystal silicon ingot is grown at an initial variable main body pull rate and a constant main body pull rate, wherein the main body of the single crystal silicon ingot is grown at the initial variable main body pull rate for less than about 20% of a length of the main body of the single crystal silicon ingot and grown at the constant main body pull rate during growth for at least about 30% of the length of the main body of the single crystal silicon ingot, wherein the constant main body pull rate is between about 0.4 mm/min and about 0.8 mm/min, and further wherein the main body of the single crystal silicon ingot has a diameter of at least about 150 millimeters;
• and
• further wherein polycrystalline is continuously fed or periodically feed to the crucible to thereby replenish a volume of molten silicon and to thereby maintain a melt elevation level in the crucible during growth of the main body of the single crystal silicon ingot and the source of nitrogen is continuously fed or periodically fed to the crucible to thereby replenish an amount of nitrogen.