Method of generating cracks in polycrystalline silicon rod and crack generating apparatus

1. A method of generating cracks in a polycrystalline silicon rod, comprising:

heating a polycrystalline silicon rod; and

subsequently performing local portion cooling of the polycrystalline silicon rod to apply a refrigerant fluid onto at least one spot-like area of a surface of the polycrystalline silicon rod, wherein

ejecting the refrigerant fluid from nozzles arranged on both sides of the polycrystalline silicon rod;

a plurality of nozzles are arranged with spaces between adjacent nozzles on each side of the polycrystalline silicon rod along a lengthwise direction of the rod such that a substantially middle position of each space between adjacent nozzles on a first side faces a nozzle on a second side, so as the refrigerant fluid to be applied to a plurality of positions dispersed on the surface of the polycrystalline silicon rod; and

each of the spot-like area has a diameter of not smaller than 0.20D and not larger than 0.32D, where D denotes a diameter of the polycrystalline silicon rod.

2. The method of generating cracks in a polycrystalline silicon rod according to claim 1 , wherein

ejecting the refrigerant fluid from each of the nozzles which has a cross-sectional area of aperture of not less than 0.5 mm 2 and not more than 20 mm 2 , and ejecting the refrigerant fluid from a tip of the nozzle placed at a distance of not shorter than 1 mm and not longer than 200 mm from a surface of the polycrystalline silicon rod.

3. The method of generating cracks in a polycrystalline silicon rod according to claim 1 , wherein

spraying the refrigerant fluid to the polycrystalline silicon rod with a flow rate of not less than 0.0006 m 3 /minute and not more than 0.006 m 3 /minute on each of the spot-like area on the surface of the polycrystalline silicon rod.

4. The method of generating cracks in a polycrystalline silicon rod according to claim 1 , further comprising entire cooling to make a refrigerant substance contact an entire surface of the polycrystalline silicon rod after the local portion cooling.

5. The method of generating cracks in a polycrystalline silicon rod according to claim 4 , wherein performing the entire cooling by a water bath configured to spray water to the surface of the polycrystalline silicon rod installed in the water bath.

6. The method of generating cracks in a polycrystalline silicon rod according to claim 4 , wherein performing the entire cooling by spraying shower of refrigerant fluid to the entire surface of the polycrystalline silicon rod.

7. The method of generating cracks in a polycrystalline silicon rod according to claim 4 , wherein the refrigerant substance is a refrigerant fluid.

8. A method of producing lumps of polycrystalline silicon, comprising:

generating cracks in a polycrystalline silicon rod in accordance with a method of claim 4 ; and

performing crushing the polycrystalline silicon rod into lumps of polycrystalline silicon by mechanical impact after the entire cooling.

9. The method of generating cracks in a polycrystalline silicon rod according to claim 1 , wherein processing a plurality of polycrystalline silicon rods simultaneously.

10. The method of generating cracks in a polycrystalline silicon rod according to claim 1 , wherein spraying water to the polycrystalline silicon rod from the first and the second side of nozzles arranged on both sides at different levels with an interval of time.

11. The method of generating cracks in a polycrystalline silicon rod according to claim 1 , wherein spraying water to the polycrystalline silicon rod from the first and the second side of nozzles arranged on both sides at same levels alternately from a different side.

12. A method of generating cracks in a polycrystalline silicon rod, comprising:

heating a polycrystalline silicon rod, and

subsequently performing local portion cooling of the polycrystalline silicon rod to apply a refrigerant fluid onto at least one spot-like area of a surface of the polycrystalline silicon rod, wherein

ejecting the refrigerant fluid from nozzles arranged on both sides of the polycrystalline silicon rod;

a plurality of nozzles are arranged with spaces between adjacent nozzles on each side of the polycrystalline silicon rod along a lengthwise direction of the rod such that a substantially middle position of each space between adjacent nozzles on a first side faces a nozzle on a second side, so as the refrigerant fluid to be applied to a plurality of positions dispersed on the surface of the polycrystalline silicon rod; and

the local portion cooling is performed such that a difference in temperature between the center of the spot-like area and a position that is distant from the center by two times the diameter of the spot-like area is not lower than 150° C.

13. The method of generating cracks in a polycrystalline silicon rod according to claim 12 , wherein

ejecting the refrigerant fluid from each of the nozzles which has a cross-sectional area of aperture of not less than 0.5 mm 2 and not more than 20 mm 2 , and ejecting the refrigerant fluid from a tip of the nozzle placed at a distance of not shorter than 1mm and not longer than 200 mm from a surface of the polycrystalline silicon rod.

14. The method of generating cracks in a polycrystalline silicon rod according to claim 12 , wherein

spraying the refrigerant fluid to the polycrystalline silicon rod with a flow rate of not less than 0.0006 m 3 /minute and not more than 0.006 m 3 /minute on each of the spot-like area on the surface of the polycrystalline silicon rod.

15. The method of generating cracks in a polycrystalline silicon rod according to claim 12 , further comprising

entire cooling to make a refrigerant substance contact an entire surface of the polycrystalline silicon rod after the local-portion cooling.

16. The method of generating cracks in a polycrystalline silicon rod according to claim 15 , wherein

the refrigerant substance is a refrigerant fluid.

17. A method of producing lumps of polycrystalline silicon, comprising:

generating cracks in a polycrystalline silicon rod in accordance with a method of claim 15 ; and

performing crushing the polycrystalline silicon rod into lumps of polycrystalline silicon by mechanical impact after the entire cooling.

18. The method of generating cracks in a polycrystalline silicon rod according to claim 12 , wherein

processing a plurality of polycrystalline silicon rods simultaneously.

19. The method of generating cracks in a polycrystalline silicon rod according to claim 15 , wherein

performing the entire cooling by a water bath configured to spray water to the surface of the polycrystalline silicon rod installed in the water bath.

20. The method of generating cracks in a polycrystalline silicon rod according to claim 12 , wherein

spraying water to the polycrystalline silicon rod from the first and the second side of nozzles arranged on both sides at different levels with an interval of time.

21. The method of generating cracks in a polycrystalline silicon rod according to claim 12 , wherein

spraying water to the polycrystalline silicon rod from the first and the second side of nozzles arranged on both sides at same levels alternately from a different side.

22. The method of generating cracks in a polycrystalline silicon rod according to claim 15 , wherein

performing the entire cooling by spraying shower of refrigerant fluid to the entire surface of the polycrystalline silicon rod.

23. The method of generating cracks in a polycrystalline silicon rod according to claim 12 , wherein

each of the spot-like area has a diameter of not smaller than 0.20D and not larger than 0.32D, where D denotes a diameter of the polycrystalline silicon rod.