JPH08239292A - Growth of crystal - Google Patents

Abstract

PURPOSE: To enable the precise control so as to provide the oxygen concentration in a single crystal with a medium one by limiting the application direction of a magnetic field, rotative direction and speed of a crystal add a crucible in growing a semiconductor single crystal according to the magnetic field-applied type Czochralski process. CONSTITUTION: The following means are used in growing a semiconductor single crystal according to the magnetic field-applied type Czochralski process: That is, (1) the application direction of the magnetic field is a transverse magnetic field in which the direction intersects the pulling up direction of the crystal at right angles and (2) the rotative direction of a crucible is in-phase with that of the crystal; the rotational frequency of the crucible is 2-16r.p.m. and the rotational speed of the crystal is higher than that of the crucible. The oxygen concentration in the crystal is controlled to 1.0-1.8×10<18> cm<-3> according to the above means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystal growth method, and more particularly to a crystal growth method suitable for crystal growth of silicon.

[0002]

2. Description of the Related Art Conventionally, a method of growing a silicon single crystal by the Czochralski method has been proposed which attempts to control the oxygen concentration in silicon by applying a magnetic field (Japanese Patent Publication No. S58-50953). (See the official gazette).

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
Japanese Patent Publication No. 953 and the like exemplify a method of applying a magnetic field in a transverse magnetic field, that is, in a direction orthogonal to the pulling direction of a silicon single crystal. According to this method, the direction of rotation of the crucible containing the silicon melt is generally opposite to the direction of rotation of the silicon single crystal (reverse phase), and particularly low concentration of oxygen (1.0 × 10 ¹⁷ ~ 1.0 x 10 ¹⁸ c
m ⁻³ ) and high concentration (1.8 × 10 ^{18 to} 2.5 × 10 ¹⁸ c
Excellent controllability of m ^-3 ). However, medium concentration (1.0
^{× 10 18 ~1.8 × 10 18 cm} -3) always good results for the control of oxygen could not be obtained. It should be noted that, by introducing oxygen into silicon, a gettering action can be provided, and therefore, from the viewpoint of gettering, it is preferable that the oxygen concentration be high, but if it is too high, a problem of defects occurs, so that it is appropriate. It is kept at a medium concentration. The present invention provides a crystal growth method capable of solving the above problems.

[0004]

That is, in the present invention, as described above, the Czochralski method is performed in the conventional transverse magnetic field, that is, while applying the transverse magnetic field in the direction orthogonal to the crystal pulling direction from the melt. In the crystal growth method according to the present invention, in the present invention, the rotation direction of the crucible containing the melt,
By making the rotation direction of the single crystal to be in phase with the rotation direction of the crystal higher than the rotation speed of the crucible,
The oxygen concentration in the pulled single crystal was set to 1.0 × 10 ^{18 of the} medium concentration.
and controlling the ^{cm -3 ~1.8 × 10 18 cm -3} .

Further, according to the present invention, the melt is accommodated in the crystal growth method by the Czochralski method which is performed while applying the magnetic field to the melt in the transverse magnetic field which is the direction orthogonal to the pulling direction of the crystal as described above. By setting the rotation direction of the crucible and the rotation direction of the silicon single crystal to be pulled as the same phase, and setting the rotation speed of the crucible to 2 to 16 rpm and making the rotation speed of the crystal larger than the rotation speed of the crucible, the oxygen concentration in the pulled single crystal is increased. With a medium concentration of 1.0 × 10 ¹⁸ cm ⁻³
It is characterized by controlling to 1.8 × 10 ¹⁸ cm ⁻³ .

According to the present invention, as is well known, the effect of the uniformity of the oxygen concentration distribution in the radial direction of the pull-grown single crystal body when the transverse magnetic field is applied is contained, and the melt is accommodated. The rotation direction of the crucible and the rotation direction of the single crystal are not the opposite directions to the conventional one but the same direction, the rotation speed of the crystal is made larger than the rotation speed of the crucible, and the rotation speed of the crucible is set to 2 to 16 rpm. This makes it possible to precisely control the medium oxygen concentration.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION

[Example] In FIG. 1, a curve A is a single crystal according to the present invention by the Czochralski method performed by applying a magnetic field to a melt of silicon (Si) in a direction (transverse magnetic field) orthogonal to the pulling direction of the crystal. In the method of growing silicon, the concentration of oxygen to be introduced into silicon is 1.3 to 1.5 × 10 ^18.
As cm ^-3 (conversion coefficient ASTM F121-79),
Within the silicon single crystal from the start to the end of crystal growth, the rotation direction (rotation speed 3.2 rpm) of the crucible containing the silicon melt and the rotation direction (rotation speed 25 rpm) of the pulled silicon single crystal are the same. Is a measurement of the concentration of oxygen actually introduced in the cross-section portion with respect to the length direction. According to the present invention, according to the present invention, in the transverse magnetic field, the rotational directions of the crucible and the silicon single crystal were in phase, and the rotational speed of the crystal was set to be higher than the rotational speed of the crucible, so that the oxygen concentration in the crystal was within a desired range. It turns out that it can be controlled within. The diameter of the crystal was also kept at the specified 125 mm.

[Comparative Example] As a comparative example, as shown by the chain line B in FIG. 1, the oxygen concentration to be introduced and the rotation speeds of the crucible and the silicon single crystal are the same as those in the above-mentioned embodiment. The rotation directions of the crucible and the single crystal are opposite to each other as in the conventional method, and the oxygen concentration in the cross-section portion with respect to the length direction in the crystal from the start to the end of the growth of the silicon single crystal is measured. According to this graph, the oxygen concentration in the silicon single crystal has a portion that deviates significantly from the predetermined concentration range, and exceeds 2.0 × 10 ¹⁸ cm ⁻³ at the maximum. The length of the defective portion in which the oxygen concentration deviated from the predetermined value was about 5 mm to 150 mm. It was also found that this resulted in a significant decrease in the non-defective rate and facilitated the formation of dislocations. The diameter of the crystal suddenly increased to 132 mm from the specified 125 mm, then decreased to 122 mm, and returned to the specified 125 mm.

The rotation speeds of the crucibles in the above-mentioned Examples and Comparative Examples are both 3.2 rpm, but the speed is 5.6.
Even when the speed was increased to rpm, almost the same results were obtained for the oxygen concentration and the crystal diameter.

Next, as shown in FIG. 2, although the rotation directions of the crucible and the silicon single crystal are in phase, the rotation speed of the crucible was changed and the relationship with the oxygen concentration in the silicon single crystal was measured. In the same figure, the solid line region C shows the oxygen concentration in the silicon single crystal according to this example. From this graph, it is possible to precisely control the oxygen concentration up to the crucible rotation speed of 16 rpm, but in order to set the oxygen concentration in the silicon single crystal to 2.0 × 10 ¹⁸ cm ⁻³ , the crucible rotation speed When the value was higher than 16 rpm, on the contrary, the flow of the silicon melt changed and not only the oxygen concentration but also the diameter of the crystal fluctuated. Therefore, in order to obtain the oxygen concentration of 1.0 to 1.8 × 10 ¹⁸ cm ⁻³ , the rotation speed of the crucible is set to 2 to 16 rpm.

In the region D indicated by the alternate long and short dash line in the figure, the controllability of the oxygen concentration with respect to the rotation speed of the crucible is measured with the rotation direction of the crucible and the single crystal in the above-mentioned embodiment being the same as the conventional reverse direction. . From this graph, according to the conventional reverse phase rotation, the oxygen concentration can be controlled when the rotation speed of the crucible is less than 2 rpm and greater than 16 rpm, but in the range of 2 to 16 rpm, the desired medium oxygen concentration It turns out that it is difficult to control.

[0012]

According to the present invention, in the crystal growth method by the Czochralski method while applying a transverse magnetic field to the semiconductor melt, the introduction of medium concentration oxygen into the single crystal semiconductor is precisely controlled. Easy to do. Then, the crystal diameter is controlled to a predetermined value, and a good semiconductor crystal free from dislocation can be obtained.

[Brief description of drawings]

FIG. 1 is a graph showing measurement of oxygen concentration in a cross-section of a silicon single crystal in the lengthwise direction.

FIG. 2 is a graph showing the measured oxygen concentration with respect to the rotation speed of the crucible.

Claims (2)

[Claims] 1. A crystal growth method according to the Czochralski method, which is performed while applying a magnetic field to a semiconductor melt, wherein a direction of applying the magnetic field is a transverse magnetic field which is a direction orthogonal to a crystal pulling direction. By setting the rotation direction of the crucible containing the liquid and the rotation direction of the crystal to be in phase, and setting the rotation speed of the crystal to be higher than the rotation speed of the crucible, the oxygen concentration in the crystal is 1.0 to 1.8 ×. A crystal growth method characterized by controlling to 10 ¹⁸ cm ⁻³ . 2. A crystal growth method according to the Czochralski method, which is performed while applying a magnetic field to a semiconductor melt, wherein the magnetic field is applied in a transverse magnetic field which is a direction orthogonal to the crystal pulling direction. With the rotation direction of the crucible containing the liquid and the rotation direction of the crystal being in phase, the rotation speed of the crucible was set to 2 to
The crystal growth method is characterized in that the oxygen concentration in the crystal is controlled to 1.0 to 1.8 × 10 ¹⁸ cm ⁻³ by setting the rotation speed of the crystal to 16 rpm and making the rotation speed of the crystal higher than the rotation speed of the crucible. .