Single crystal of silicon with <100> orientation, which is doped with n-type dopant, and method for producing such a single crystal
Single crystal silicon with <100> orientation is doped with n-type dopant and comprises a starting cone, a cylindrical portion and an end cone, a crystal angle being not less than 20° and not greater than 30° in a middle portion of the starting cone, the length of which is not less than 50% of a length of the starting cone, and edge facets extending from a periphery of the single crystal into the single crystal, the edge facets in the starting cone and in the cylindrical portion of the single crystal in each case having a length which is not more than 700 μm.
1. A method for producing a silicon single crystal with <100> orientation, comprising:
doping a melt of silicon with n-type dopant;
pulling a starting cone, a cylindrical portion and an end cone of the single crystal by the CZ method;
pulling the starting cone with a crystal angle of not less than 20° and not more than 30° in a middle portion of the starting cone, the length of which middle portion is not less than 50% of a length of the starting cone, fluctuations of the crystal angle being limited by means of angle control to not more than 0.01°/s;
pulling the cylindrical portion of the single crystal at a pulling rate that is not more than 75% of a limit pulling rate, in the event of the limit pulling rate being exceeded, deformation of the single crystal prevents continuation of the pulling; and
actively cooling the single crystal, including the starting cone, in a region in the vicinity of a phase boundary between the growing single crystal and the melt.
2. The method of claim 1 , further comprising the pulling the single crystal in a transitional region between the starting cone and the cylindrical portion at a pulling rate of not more than 1.5 mm/min.
3. The method of claim 1 , wherein cooling of the single crystal is achieved by means of a water cooling.
4. The method of claim 2 , wherein cooling of the single crystal is achieved by means of a water cooling.
5. The method of claim 1 , further comprising: slicing semiconductor wafers from the cylindrical portion of the single crystal.