Single crystal and semiconductor wafer and apparatus and method for producing a single crystal

A seal for use in an apparatus for producing a single crystal of semiconductor material, the apparatus including a chamber defining an inner wall, a crucible disposed in the chamber, a crucible heater substantially surrounding the crucible, a radiation shield for shielding the single crystal, and thermal insulation disposed between the crucible heater and the inner wall of the chamber, the thermal insulation and the inner wall defining a gap therebetween, the seal comprising:

• a resilient material that seals the gap between the inner wall and the thermal insulation, the resilient material providing a substantial obstacle against transport of gaseous iron carbonyls to the single crystal.

A system for reducing transport of gaseous iron carbonyls to a single crystal in a crystal-growing apparatus, the apparatus including a chamber defining an inner wall, a crucible disposed in the chamber, a crucible heater substantially surrounding the crucible, a radiation shield for shielding the single crystal, and thermal insulation disposed between the crucible heater and the inner wall of the chamber, the thermal insulation and the inner wall defining a gap therebetween, the system comprising:

• a resilient seal disposed in the gap between the inner wall and the thermal insulation;
• and
• an active cooling system disposed adjacent the single crystal to cool the single crystal during growth.

A method for producing a single crystal of semiconductor material by pulling the single crystal from a crucible in a chamber that defines an inner wall, wherein the crucible is substantially surrounded by a crucible heater, and further wherein a thermal insulation is disposed within the chamber and the thermal insulation and the inner wall define a gap therebetween, the method comprising the steps of:

• substantially sealing the gap with a resilient seal to form an obstacle against transport of gaseous iron carbonyls to the single crystal.

A single crystal of semiconductor material having an iron concentration, the single crystal comprising a section of substantially cylindrical shape defining a circumference, a radius (R) and an edge region extending from the circumference to a distance of R-5 mm radially into the single crystal, wherein the iron concentration in the edge region is less than 1*109 atoms/cm3.

A semiconductor wafer having an iron concentration and defining a circumference, a radius (R) and an edge region extending from the circumference to a distance of R-5 mm radially into the semiconductor wafer, wherein the iron concentration in the edge region is less than 1*109 atoms/cm3.