Method for manufacturing single crystal semiconductor
A method for manufacturing a single crystal semiconductor, in which, in a process of pulling up the single crystal semiconductor from melt for growing it, an impurity is incorporated more uniformly into the single crystal semiconductor so that a variation in impurity concentration across the semiconductor wafer surface can be reduced, and thus, the planarity of the wafer can be improved. In the process of pulling-up the single crystal semiconductor ( 6 ), fluctuation in a pulling-up speed is controlled, whereby the variation in concentration of the impurity in the single crystal semiconductor ( 6 ) is reduced. Especially, a width of speed fluctuation (ΔV) in 10 seconds is adjusted to less than 0.025 mm/min. Furthermore, in carrying out the control for adjusting the pulling-up speed such that a diameter of the single crystal semiconductor ( 6 ) becomes a desired diameter, a magnetic field having strength of 1,500 gauss or more is applied to the melt ( 5 ).
1. A method for manufacturing a single crystal semiconductor, in which a seed crystal is dipped into melt in a crucible and is pulled up at a pulling-up speed corresponding to a pulling-up instruction to manufacture the single crystal semiconductor having an impurity added thereto, including the steps of:
determining a deviation between a target value of a crystal diameter and a current value of the crystal diameter,
controlling the amount of increase/decrease in speed from a current pulling-up speed to make the amount of the pulling-up instruction for making the deviation of the crystal diameter zero and setting a limit to a range of the pulling-up speed such that a pulling-up speed fluctuation in 10 seconds is less than 0.025 mm/min, and,
outputting the pulling-up instruction to a pulling up mechanism to increase/decrease the pulling-up speed by the controlled amount of increase/decrease in speed from the current pulling-up speed, and pulling up the single crystal semiconductor.
2. The method for manufacturing the single crystal semiconductor of claim 1 , wherein,
when the single crystal semiconductor is pulled up, a magnetic field of 1500 gauss or above is applied to the melt.
3. The method for manufacturing the single crystal semiconductor of claim 1 , wherein
the impurity to be added into the single crystal semiconductor is boron B or gallium Ga, and the impurity concentration is 8.0e17 atoms/cc or more.
4. The method for manufacturing the single crystal semiconductor of claim 1 , wherein
the impurity to be added into the single crystal semiconductor is phosphorus P, antimony Sb, or arsenic As, and the impurity concentration is 5.0e17 atoms/cc or more.
5. The method for manufacturing the single crystal semiconductor of claim 1 , wherein
The current value of the crystal diameter is determined by the weight of the crystal.
6. The method for manufacturing the single crystal semiconductor claim 1 , wherein
The current value of the crystal diameter is determined by optical method.