Process for producing p-doped and epitaxially coated semiconductor wafers from silicon
View Patent ↗The Czochralski method is used for producing p − -doped and epitaxially coated semiconductor wafers from silicon, wherein a silicon single crystal is pulled, and during the pulling is doped with boron, hydrogen and nitrogen, and the single crystal thus obtained is processed to form p − -doped semiconductor wafers which are epitaxially coated.
1. A process for producing an epitaxillay coated p − -doped semiconductor wafer from silicon, comprising:
pulling a silicon single crystal using the Czochralski method and during this pulling, doping the silicon single crystal with boron, hydrogen and nitrogen to form a p − -doped single crystal and controlling a nitrogen concentration C n in the silicon single crystal in accordance with an oxygen concentration C O ; and
processing the p − -doped single crystal to form at least one p − -doped semiconductor wafer, and epitaxially coating the p − -doped semiconductor wafer to form an epitaxially coated p − -doped semiconductor wafer.
2. The process of claim 1 , wherein the single crystal is pulled under a hydrogen partial pressure of 0.2 to 2.5 mbar.
3. The process of claim 2 , wherein the p − -doped semiconductor wafers have a nitrogen concentration of greater 1×10 14 cm −3 and less than 1×10 15 cm −3 .
4. The process of claim 3 , wherein an inclusion of oxygen in the p − -doped single crystal is reduced such that the p − -doped single crystal has an oxygen content of 5.5×10 17 cm −3 or less.
5. The process of claim 2 , wherein an inclusion of oxygen in the p − -doped single crystal is reduced such that the p − -doped single crystal has an oxygen content of 5.5×10 17 cm −3 or less.
6. The process of claim 2 , wherein the epitaxially coated p − -doped semicondutor wafers are p/p − -doped epi wafers.
7. The process of claim 1 , wherein the p − -doped semiconductor wafers have a nitrogen concentration of greater 1×10 14 cm −3 and less than 1×10 15 cm −3 .
8. The process of claim 7 , wherein an inclusion of oxygen in the p − -doped single crystal is reduced such that the p − -doped single crystal has an oxygen content of 5.5×10 17 cm −3 or less.
9. The process of claim 7 , wherein the epitaxially coated p − -doped semicondutor wafers are p/p − -doped epi wafers.
10. The process of claim 1 , wherein an inclusion of oxygen in the p − -doped single crystal is reduced such that the p − -doped single crystal has an oxygen content of 6×10 17 cm −3 or less.
11. The process of claim 10 , wherein the epitaxially coated p − -doped semicondutor wafers are p/p − -doped epi wafers.
12. The process of claim 1 , wherein an inclusion of oxygen in the p − -doped single crystal is reduced such that the p − -doped single crystal has an oxygen content of 5.5×10 17 cm −3 or less.
13. The process of claim 1 , wherein the epitaxially coated p − -doped semicondutor wafers are p/p − -doped epi wafers.
14. The process of claim 1 , wherein the nitrogen concentration is controlled so that it is within a region which is limited by an upper boundary concentration and a lower boundary concentration, the upper boundary concentration being calculated by the formula
C N =2715×10 14 ×exp(−0.91×10 17 ×C O )
and the lower boundary concentration being calculated by the formula
C N =235 ×10 14 ×exp(−0.91×10 17 ×C O ),
with C O and C N having the dimension [1/cm 3 ].
15. The process of claim 1 , wherein a boron concentration in the p 31 -doped silicon single crystal is between 1×10 17 cm −3 and 1×10 13 cm −3 , the p − -doped single crystal is pulled under a hydrogen partial pressure of 0.2 to 2.5 mbar, a nitrogen concentration in the p − -doped single crystal is between 1×10 14 cm −3 and 1×10 15 cm −3 , and the oxygen concentration is less than or equal to 6×10 17 cm −3 .
16. The process of claim 15 , wherein the oxygen concentration is less than or equal to 5.5×10 17 cm −3 .
17. The process of claim 1 , wherein the p − -doped semiconductor wafers contain BMDs in a concentration of 5×10 8 cm −3 to 10 10 cm −3 .
18. The process of claim 1 , wherein an epitaxial coating of the p −- doped semiconductor wafers has a thickness of from 1 to 5 μm.
19. The process of claim 18 , wherein the epitaxial coating contains boron in a concentration of 2×10 16 cm −3 to 1×10 15 cm −3 .
20. The process of claim 1 , wherein an epitaxial coating on the p − -doped semiconductor wafers have less than 40 layer defects of a size larger than 0.09 μm based on the area of a 200 mm wafer.