Process for production of silicon single crystal
In growing a silicon monocrystal from a silicon melt added with an N-type dopant by Czochralski method, the monocrystal is grown such that a relationship represented by a formula (1) as follows is satisfied. In the formula (1): a dopant concentration in the silicon melt is represented by C (atoms/cm 3 ); an average temperature gradient of the grown monocrystal is represented by Gave(K/mm); a pulling-up speed is represented by V (mm/min); and a coefficient corresponding to a kind of the dopant is represented by A. By growing the silicon monocrystal under a condition shown in the left to a critical line G 1 , occurrence of abnormal growth due to compositional supercooling can be prevented. Gave V > A · C - 43 ( 1 )
1. A method of manufacturing a silicon monocrystal, the silicon monocrystal being grown by the Czochralski method from a silicon melt with an N-type dopant added, the method comprising:
preliminarily growing silicon monocrystals by the Czochralski method from silicon melts with the N-type dopant added under various dopant concentrations C (atoms/cm 3 ), and obtaining for each of the grown monocrystals a ratio G ave /V between an average temperature gradient G ave (K/mm) and a pulling-up speed V (mm/min);
preparing a scatter diagram of the dopant concentrations C and ratios G ave /V corresponding to the grown monocrystals, in which the dopant concentration C is plotted on a horizontal axis and the ratio G ave /V is plotted on a vertical axis;
identifying in the scatter diagram a critical line at which compositional supercooling occurs; and
based on the critical line, growing the silicon monocrystal such that G ave /V of the grown monocrystal has a value at which the compositional supercooling does not occur, at the dopant concentration C of the silicon melt.
2. The method according to claim 1 , wherein:
the N-type dopant is arsenic; and
the silicon monocrystal is grown such that the following formula is satisfied:
Gave
V
>
A
·
C
-
43
(
1
)
where:
A is 2.85×10 −19 ; and
C is the dopant concentration in atoms/cm 3 .
3. The method according to claim 1 , wherein:
the N-type dopant is phosphorus; and
the silicon monocrystal is grown such that the following formula is satisfied:
Gave
V
>
A
·
C
-
43
(
2
)
where:
A is 2.00×10 −19 ; and
C is the dopant concentration in atoms/cm 3 .