Silicon wafer for semiconductor and manufacturing method thereof
View Patent ↗Silicon wafers having a density of BMDs with sizes between 20 to 40 nm at positions ≧20 μm below the wafer surface in the range of 5×10 11 /cm 3 , and a density of BMDs with sizes of ≧300 nm≦1×10 7 /cm 3 , exhibit reduced slip dislocation and warpage. The wafers are sliced from a crystal grown under specific conditions and then subjected to both low temperature heat-treatment and high temperature anneal.
1. A silicon wafer having, at a position ≧20 μm or more from a wafer surface, a density of BMDs with sizes of 20 nm to 40 nm in the range of 5×10 11 /cm 3 to 5×10 13 /cm 3 , and having a density of BMDs with sizes of 300 nm or more equal to or less than 1×10 7 /cm 3 .
2. The silicon wafer of claim 1 , which is doped with nitrogen.
3. The silicon wafer of claim 1 , which is doped with hydrogen.
4. The silicon wafer of claim 2 , which is doped with hydrogen.
5. A method for manufacturing a silicon wafer of claim 1 , comprising growing a silicon single crystal ingot while maintaining a cooling rate in a range in which a center temperature of the crystal during crystal growth changes from 1000° C. to 900° C. at a rate of 5° C./min or more; heat treating a wafer sliced from the ingot at a temperature of 400° C. to 850° C. for 30 minutes to 4 hours; high temperature annealing by heat treating the wafer at a temperature of 1100° C. to 1250° C. for 10 minutes to 2 hours under an atmosphere of rare gas having an impurity concentration of 0.5% or less by volume or under a non-oxidizing atmosphere, wherein the thickness of any oxidized film after heat treating is 2 nm or less.
6. The method of claim 5 , wherein the oxygen concentration of the wafer immediately after being sliced from the crystal is in the range of 7×10 17 atoms/cm 3 to 9×10 17 atoms/cm 3 .
7. The method of claim 5 , wherein the nitrogen concentration of the wafer immediately after being sliced from a crystal is in a range of 1×10 13 atoms/cm 3 to 8×10 15 atoms/cm 3 .
8. The method of claim 6 , wherein the nitrogen concentration of the wafer immediately after being sliced from a crystal is in a range of 1×10 13 atoms/cm 3 to 8×10 15 atoms/cm 3 .
9. The manufacturing method of claim 7 , wherein the growth of the silicon single crystal ingot is performed from a melt to which nitrogen is added such that the nitrogen concentration falls in a range of 1×10 16 atoms/cm 3 to 1×10 19 atoms/cm 3 .
10. The manufacturing method of claim 5 , wherein the growth of the silicon single crystal ingot is performed from a melt to which nitrogen is added such that the nitrogen concentration falls in a range of 1×10 16 atoms/cm 3 to 1×10 19 atoms/cm 3 .
11. The method of claim 6 , wherein the hydrogen concentration of the wafer immediately after being sliced from a crystal is in a range of 1×10 12 atoms/cm 3 to 5×10 16 atoms/cm 3 .
12. The method of claim 7 , wherein the hydrogen concentration of the wafer immediately after being sliced from a crystal is in a range of 1×10 12 atoms/cm 3 to 5×10 16 atoms/cm 3 .
13. The method of claim 8 , wherein the hydrogen concentration of the wafer immediately after being sliced from a crystal is in a range of 1×10 12 atoms/cm 3 to 5×10 16 atoms/cm 3 .
14. The method of claim 9 , wherein the hydrogen concentration of the wafer immediately after being sliced from a crystal is in a range of 1×10 12 atoms/cm 3 to 5×10 16 atoms/cm 3 .
15. The method of claim 10 , wherein the growth of the silicon single crystal ingot is performed under an atmosphere where hydrogen gas is continuously introduced such that the concentration of hydrogen is within the range of 0.01% to 3% at a volume ratio.
16. The method of claim 5 , wherein in a further step, a silicon single crystal epi-layer is epitaxially deposited after the high-temperature anneal.