Silicon wafer with homogeneous radial oxygen variation
The invention relates to a silicon wafer having a radial variation of oxygen concentration of less than 7%, determined over the entire radius of the silicon wafer. The wafers are produced in the P V region with rotation of crystal and crucible in the same direction, and in the presence of a horizontal magnetic field of defined intensity.
1. A silicon wafer with a diameter of at least 300 mm, sliced from a silicon single crystal pulled according to the CZ method, having a radial variation of oxygen concentration of less than 7%, calculated according to (O max −O min /O min )*100%, wherein O max is the maximal and O min is the minimal oxygen concentration determined over the entire radius of the silicon wafer.
2. The silicon wafer of claim 1 , wherein the radial variation of the oxygen concentration is less than 5%.
3. The silicon wafer of claim 1 , wherein the radial variation of the oxygen concentration is less than 2%.
4. The silicon wafer of claim 1 , wherein the silicon wafer is doped with nitrogen and has a nitrogen concentration of not less than 5×10 12 atoms/cm 3 and not more than 3.5×10 13 atoms/cm 3 .
5. The silicon wafer of claim 1 , wherein an oxygen concentration in the silicon wafer is from 5×10 17 atoms/cm 3 to 6×10 17 atoms/cm 3 .
6. The silicon wafer of claim 5 , wherein the silicon wafer is doped with hydrogen and has a hydrogen concentration of not less than 3×10 13 atoms/cm 3 and not more than 8×10 13 atoms/cm 3 .
7. An epitaxial silicon wafer which is p/p+ doped, comprising a silicon wafer of claim 1 , as a substrate, the epitaxial silicon wafer comprising BMD nuclei whose density, averaged over the radius of the silicon wafer, is not less than 1×10 5 cm −3 and not more than 1×10 7 cm −3 , a density of BMD nuclei differing by no more than 20% from the average value from the center to the edge of the epitaxial silicon wafer.
8. The epitaxial silicon wafer of claim 7 , wherein a resistivity is not less than 5 mΩcm and not more than 10 mΩcm.
9. An epitaxial silicon wafer which is p/p− doped, comprising a silicon wafer of claim 1 , as a substrate, the epitaxial silicon wafer having a BMD density in the region of the silicon substrate wafer from the center to the edge of the epitaxial silicon wafer of not less than 1×10 8 cm −3 after a heat treatment at a temperature of 1000° C. over a period of 16 h, a density of BMD differing by no more than 20% from the average value from the center to the edge of the epitaxial silicon wafer.
10. A method for producing a silicon wafer of claim 1 , comprising:
a) providing a silicon melt in a crucible;
b) pulling a silicon single crystal from the melt according to the CZ method, oxygen being incorporated into the single crystal;
c) applying a horizontal magnetic field to the melt during the pulling of the silicon single crystal;
d) rotating the growing crystal and the crucible during the pulling of the single crystal;
e) providing the silicon wafer by processing the silicon single crystal;
wherein a magnetic flux density of the applied horizontal magnetic field is 1900-2600 Gs in the middle of the crucible, and the growing crystal is rotated at at least 8 rpm.
11. The method as claimed in claim 10 , wherein the magnetic flux density is 2000-2400 Gs.
12. The method of claim 10 , wherein the magnetic flux density is 2150-2350 Gs.
13. The method of claim 10 , wherein the crystal and the crucible are rotated in the same sense, wherein the crucible is rotated at 0.3-0.8 rpm.
14. The method of claim 10 , wherein the crystal is rotated at at least 10 rpm.
15. The method of claim 13 , wherein the crystal is rotated at at least 10 rpm.