Method for manufacturing silicon wafer and silicon wafer manufactured by this method
A method for manufacturing a silicon wafer having a defect-free region in a surface layer, in which at least only a surface layer region to a predetermined depth from a front surface of a silicon wafer to be processed is subjected to heat treatment at a temperature of not less than 1100 degrees C. for not less than 0.01 msec to not more than 1 sec, to thereby make the surface layer defect-free. As a result of this, there is provided a method for manufacturing a silicon wafer, in which a DZ layer without generation of crystal defects from the front surface to a constant depth can be uniformly formed, and oxide precipitates having a steep profile inside the wafer can be secured and controlled with a high degree of accuracy.
1. A method for manufacturing a silicon wafer having a defect-free region in a surface layer, comprising:
pre-heating a whole silicon wafer to be processed at not less than 500 degrees C. to less than 1100 degrees C.; and then
subjecting only a surface layer region to a predetermined depth from a front surface of the silicon wafer to be processed to heat treatment at a temperature of not less than 1100 degrees C. for not less than 0.01 millisecond to not more than 1 second, to thereby make the surface layer defect-free,
wherein the whole silicon wafer is sliced from a silicon single crystal ingot whose whole area in a radial direction is an N-region, the N-region being a neutral region, and the ingot being grown by the Czochralski method.
2. The method for manufacturing the silicon wafer according to claim 1 , wherein the heat treatment is performed by irradiating a laser beam with a wavelength of 0.3 to 15 μm to the silicon wafer to be processed.
3. The method for manufacturing the silicon wafer according to claim 1 , wherein the heat treatment is performed by irradiating a laser beam with a wavelength of 0.7 to 15 μm to the silicon wafer to be processed at a Brewster angle.
4. The method for manufacturing the silicon wafer according to claim 2 , wherein the heat treatment is performed by irradiating a laser beam with a wavelength of 0.7 to 15 μm to the silicon wafer to be processed at a Brewster angle.
5. The method for manufacturing the silicon wafer according to claim 4 , wherein the heat treatment is performed in a non-oxidizing atmosphere of argon, hydrogen, or a mixed gas thereof.
6. The method for manufacturing the silicon wafer according to claim 4 , wherein the heat treatment is performed in an atmosphere conducive to forming nitride film of nitrogen or ammonia.
7. The method for manufacturing the silicon wafer according to claim 4 , wherein the heat treatment is performed in an oxygen atmosphere.
8. The method for manufacturing the silicon wafer according to claim 7 , wherein the silicon single crystal ingot grown by the Czochralski method has an oxygen concentration of not less than 7 ppma to not more than 20 ppma.
9. The method for manufacturing the silicon wafer according to claim 8 , wherein the silicon single crystal ingot grown by the Czochralski method has a nitrogen concentration of 1×10 11 to 1×10 15 atoms/cm 3 .
10. The method for manufacturing the silicon wafer according to claim 9 , wherein the silicon single crystal ingot grown by the Czochralski method has a carbon concentration of 1×10 16 to 1×10 17 atoms/cm 3 .
11. The method for manufacturing the silicon wafer according to claim 10 , wherein the silicon wafer to be processed is a wafer that is sliced from a silicon single crystal ingot grown by the Czochralski method and that at least is rapidly heated to 1100 to 1300 degrees C. at a rate of temperature increase of not less than 5 degrees C/sec in a non-oxidizing atmosphere to keep it for 1 to 60 seconds and subsequently is rapidly cooled at a rate of temperature decrease of not less than 5 degrees C/sec using a rapid heating and rapid cooling apparatus and then, the silicon wafer is subjected to the pre-heating and the heat treatment of only a surface layer region.
12. The method for manufacturing the silicon wafer according to claim 11 , wherein the silicon wafer to be processed is a wafer comprising a front surface that is subjected to polishing processing.
13. The method for manufacturing the silicon wafer according to claim 1 , wherein the heat treatment is performed in a non-oxidizing atmosphere of argon, hydrogen, or a mixed gas thereof.
14. The method for manufacturing the silicon wafer according to claim 1 , wherein the heat treatment is performed in an atmosphere conducive to forming nitride film of nitrogen or ammonia.
15. The method for manufacturing the silicon wafer according to claim 1 , wherein the heat treatment is performed in an oxygen atmosphere.
16. The method for manufacturing the silicon wafer according to claim 1 , wherein the silicon single crystal ingot grown by the Czochralski method has an oxygen concentration of not less than 7 ppma to not more than20 ppma.
17. The method for manufacturing the silicon wafer according to claim 1 , wherein the silicon single crystal ingot grown by the Czochralski method has a nitrogen concentration of 1×10 11 to 1×10 15 atoms/cm 3 .
18. The method for manufacturing the silicon wafer according to claim 1 , wherein the silicon single crystal ingot grown by the Czochralski method has a carbon concentration of 1×10 16 to 1×10 17 atoms/cm 3 .
19. The method for manufacturing the silicon wafer according to claim 1 , wherein the silicon wafer to be processed is a wafer that is sliced from a silicon single crystal ingot grown by the Czochralski method and that at least is rapidly heated to 1100 to 1300 degrees C. at a rate of temperature increase of not less than 5 degrees C/sec in a non-oxidizing atmosphere to keep it for 1 to 60 seconds and subsequently is rapidly cooled at a rate of temperature decrease of not less than 5 degrees C/sec using a rapid heating and rapid cooling apparatus and then, the silicon wafer is subjected to the pre-heating and the heat treatment of only a surface layer region.
20. The method for manufacturing the silicon wafer according to claim 1 , wherein the silicon wafer to be processed is a wafer comprising a front surface that is subjected to polishing processing.