Single crystal semiconductor manufacturing apparatus and manufacturing method, and single crystal ingot
A single crystal semiconductor manufacturing apparatus in which the concentration of oxygen in a single crystal semiconductor is controlled while pulling up a single crystal semiconductor such as single crystal silicon by the CZ method, a single crystal semiconductor manufacturing method, and a single crystal ingot manufactured by the method are disclosed. The natural convection ( 20 ) in the melt ( 5 ) in a quartz crucible ( 3 ) is controlled by regulating the temperatures at a plurality of parts of the melt ( 5 ). A single crystal semiconductor ( 6 ) can have a desired diameter by regulating the amount of heat produced by heating means ( 9 a ) on the upper side. Further the ratio between the amount of heat produced by the upper-side heating means ( 9 a ) and that by the lower-side heating means ( 9 b ) is adjusted to vary the process condition. In the adjustment, the amount of heat produced by the lower-side heating means ( 9 b ) is controlled to a relatively large proportion. Without inviting high cost and large size of the manufacturing apparatus, the oxygen concentration distribution in the axial direction of the single crystal semiconductor, the diameter of the single crystal semiconductor, and the minute fluctuation of the oxygen concentration in the axial direction are controlled.
1. A single crystal semiconductor manufacturing method in which a quartz crucible is accommodated inside a single crystal pulling vessel, a polycrystalline raw material is melted inside the quartz crucible, a single crystal semiconductor is pulled up from the melt inside the quartz crucible, and an oxygen concentration in the single crystal semiconductor is controlled during the pulling, comprising the steps of:
adjusting the diameter of the single crystal semiconductor to a desired diameter by controlling an output from an upper-side heating means based on a length of the single crystal semiconductor being pulled up;
adjusting a ratio of an amount of heating by a lower-side heating means to an amount of heating by the upper-side heating means by controlling the output from the lower-side heating means, so that the amount of heating by the lower side heating means is larger than the amount of heating by the upper-side heating means and thereby promoting natural convection in the melt while suppressing fluctuation in the oxygen concentration in an axial direction of the single crystal semiconductor; and
increasing a rotation speed of the quartz crucible or raising a heating temperature for the quartz crucible in a later stage of the pulling of the single crystal semiconductor, and shifting the oxygen concentration in the later stage of the pulling of the single crystal semiconductor to a high oxygen side, so that a control range of the oxygen concentration in the later stage of the pulling of the single crystal semiconductor has an equal range to a control range of the oxygen concentration in an earlier stage of the pulling, to thereby control the distribution of the oxygen concentration in the axial direction of the single crystal semiconductor as desired.
2. A single crystal semiconductor manufacturing method in which a quartz crucible is accommodated inside a single crystal pulling vessel, a polycrystalline raw material is melted inside the quartz crucible, a single crystal semiconductor is pulled up from the melt inside the quartz crucible, a single crystal semiconductor is pulled up from the melt inside the quartz crucible, and an oxygen concentration in the single crystal semiconductor is controlled during the pulling, comprising the steps of:
adjusting a diameter of the single crystal semiconductor by controlling an output from an upper-side heating means based on a length of the single crystal semiconductor being pulled up;
adjusting a ratio of an amount of heating by a lower-side heating means to an amount of heating by the upper-side heating means so that the amount of heating by the lower side heating means is smaller than the amount of heating by the upper side heating means, by controlling an output from the lower-side heating means; and
in the later stage of the pulling of the single crystal semiconductor, increasing pressure inside the single crystal pulling vessel, controlling a flow rate of argon gas introduced into the single crystal pulling vessel, controlling a distance between a heat shielding plate and a surface of the melt so that the oxygen concentration in the later stage of the pulling of the single crystal semiconductor shifts to a low oxygen side, and control range of the oxygen concentration in the later stage of the pulling of the single crystal semiconductor has a range equal to a control range of the oxygen concentration in an earlier stage of the pulling, thereby controlling a distribution of the oxygen concentration in the axial direction of the single crystal semiconductor.