JPS6033292A - Preparation of single crystal semiconductor - Google Patents

Abstract

PURPOSE:To prepare a single crystal semiconductor having low oxygen concn. and low concn. of impurity and high purity by rotating a means for impressing magnetic field to molten starting material for a semiconductor in a crucible supported freely rotatably by rotating the means synchronously with the rotation of the crucible. CONSTITUTION:Two electromagnets 11, 12 are provided to both the sides of a crucible 4 on the outside periphery of a chamber 1 arranging to confront the N pole to the S pole and impressing a magnetic field in the horizontal direction to the molten silicon 9 in the crucible 4. These electromagnets 11, 12 are constructed to be mechanically or electrically rotatable synchronously with the rotation of the crucible 4 around the chamber 1. Magnetic field in the horizontal direction is impressed to the molten silicon 9 in the crucible 4 by passing approximately DC current through a heater 5 and electromagnet 11, 12 using the pulling device and the electromagnets 11, 12 are rorated synchronously with the rotation of the crucible 4. Single crystal silicon 10 is pulled up by pulling up a chain 7 in this state.

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing a single crystal semiconductor.

Single crystal semiconductors used for manufacturing semiconductor devices are mainly manufactured by the Czochralski method (C2 method). Conventionally, a single crystal semiconductor pulling apparatus as shown in FIG. 1 has been used in this C2 method.

That is, numeral 1 in the figure is a chamber whose top and bottom are open. A rotatable support rod 2 is inserted into the lower opening of the chamber 1.

A graphite protector 3 is supported on the support rod 2 to protect the quartz crucible 4t. A cylindrical heater 6 and a heat retaining tube 6 are sequentially arranged around the outer periphery of the protector 3. Further, from the upper opening of the chamber 1, for example, a chain 7
is suspended and holds 91 seed crystals 8.

In the C2 method using the above-mentioned pulling device, for example, when manufacturing single crystal silicon, a silicon raw material is put into a Ludde 4, the silicon raw material is melted by a heater 5, and a seed crystal is added to this molten silicon 9. Soak 8, Ruth? The single crystal silicon 10 is pulled up by pulling up the chain 2 while rotating the chain 4 and the seed crystal 8 in opposite directions.

The above-described method has the disadvantage that the oxygen concentration and impurity concentration in the single crystal silicon 10 produced are high, and that a high-purity crystal cannot be obtained. This is thought to be due to the following reasons.

In other words, in the C2 method mentioned above, because of uniform heating, the temperature is 100%. However, the molten silicon 9 in the crucible 4 rotates only slowly compared to the rotation speed of the crucible 4. Because of this, Ruth? 4 is easily eroded by contact with molten silicon 9, and oxygen and other impurities contained in crucible 4 are injected into single crystal silicon 10. therefore,
It is considered that high purity crystals cannot be obtained.

In addition, the conventional C2 method has the disadvantage that the oxygen concentration distribution in the single crystal silicon 10 becomes uneven due to forced convection and thermal convection that occur in the molten silicon 9 in Ruth 7t4. 9 horizontally or lead
By applying a magnetic field in the f direction, convection is suppressed and the oxygen concentration distribution of the single crystal silicon 10 is made uniform.

By applying a magnetic field in this way, it is possible to equalize the oxygen concentration distribution, etc., but the above-mentioned Ruth? It has not been possible to prevent the increase in oxygen concentration and impurity concentration in the single crystal silicon 10 due to the erosion of 4, and it has been difficult to obtain highly pure crystals.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a complete method for producing a high purity single crystal semiconductor with low oxygen concentration and impurity concentration.

That is, the method for manufacturing a single crystal semiconductor of the present invention is based on Ruth?
The device is characterized in that it is provided with means for applying a magnetic field to the molten semiconductor raw material inside, and that the magnetic field applying means is rotated in synchronization with the rotation of the molten semiconductor material.

In this way, if the magnetic field application means is rotated in synchronization with the rotation of the crucible, the molten semiconductor raw material will be in a relatively stopped state within the crucible, or a state close to it, so that the crucible will remain relatively stationary within the crucible.
erosion can be reduced and the purity of single crystal semiconductors can be improved.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 2 and 3. Incidentally, the same members as those in FIG. 1 already described are given the same numbers and their explanations will be omitted.

Two electromagnets 11 and 12 located on both sides of the crucible 4 on the outer periphery of the chamber 1 are arranged so that their N and S poles face each other, and apply a horizontal magnetic field to the molten silicon 9 in the crucible 4. It is supposed to be done. These electrode stones11.
The circumference of the 12-chamber chamber 1 can be mechanically or electrically rotated in synchronization with the rotation of the crucible 4.

Using the above-mentioned lifting device, the heater 5 is energized with a nearly direct current, the electromagnets 11 and 12 are energized, and the entire horizontal magnetic field is applied to the molten silicon 9 in the screw 4. As shown in the figure, the single crystal silicon 10 is pulled up in substantially the same manner as the conventional method except that the electromagnets 11, 12f are rotated in synchronization with the rotation of the throne 4.

According to the above method, as the electromagnets 11 and 12 rotate, the molten silicon 9 in the crucible 4 also rotates at the same speed, so the crucible 4 and the molten silicon 9 are relatively stationary. state or a state close to it. Therefore, the erosion of the crucible 73-4 is significantly reduced, the oxygen neutralized by the molten silicon 9 and other impurities contained in the crucible 4 are reduced, and the purity of the single crystal silicon produced can be improved.

In fact, in the conventional method, after 1 charge and 24 to 30 hours of operation, the contact area with the molten silicon of about 8 to 9 +++ m thickness is eroded by about 1 to 2 cm, and as a result, the monocrystalline silicon in the produced monocrystalline silicon is eroded. The oxygen concentration was 10~20x10 cm, whereas in the method of the present invention, the erosion of the crucible was about 0.2~0.5 cm with the same 1 charge operation, and the Oxygen concentration is 4-6×1o17c
It was possible to reduce it significantly to rn″3.

Additionally, the uniformity of the oxygen concentration distribution and resistivity distribution in single-crystal silicon was also improved, making it possible to produce high-quality single-crystal silicon.

In addition, in the pulling device used in the above embodiment, a horizontal magnetic field was applied to the molten silicon 9 in the silicone 4 using two electromagnets 11 and 12, but the invention is not limited to this, for example, as shown in FIG. As shown in FIG. 2, a ring-shaped superconducting coil 13, for example, is disposed around the outer periphery of a chamber (not shown), and a vertical magnetic field is applied to the molten silicon in the Ruggi 4.
3 may be rotated in synchronization with the rotation of the crucible 4. In this case, as shown in the figure, the center of rotation of the superconducting coil 13 is eccentric from the center of rotation of the metal ring 4, so that the magnetic field applied to the molten silicon is asymmetrical, so that the center of the superconducting coil 13 is centered in the figure. If tb is carried on the broken line, erosion of the crucible 4 can be effectively prevented.

In the above explanation, the case of manufacturing single crystal silicon has been described, but it goes without saying that the method of the present invention can be similarly applied to the case of manufacturing a single crystal of GaAs or the like.

As described above in detail, the method for manufacturing a single crystal semiconductor of the present invention has remarkable effects such as manufacturing a high purity single crystal semiconductor with low oxygen concentration.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional single crystal semiconductor pulling device, FIG. 2 is a sectional view of a single crystal semiconductor pulling device used in an embodiment of the present invention, and FIG. 3 is a sectional view of a conventional single crystal semiconductor pulling device used in an embodiment of the present invention. FIG. 4 is an explanatory diagram showing a method for manufacturing a crystalline semiconductor. FIG. 4 is a diagram showing a method for manufacturing a single crystal semiconductor in another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Chamber, 2... Support rod, 3... Protector, 4... Crucible, 5... Heater, 6... Heat insulation cylinder,
7... Chain, 8... Muku crystal, 9... Molten silicon, 1°... Single crystal silicon, 11.12... Electromagnet, 13... Superconducting coil.

Claims (1)

[Claims] Ruth in the chamber? A method for producing a single crystal semiconductor by rotatably supporting the crucible, dipping a seed crystal rotatably suspended from above the crucible into the molten semiconductor raw material in the crucible, and pulling up the nuclide crystal. A method for manufacturing a single crystal semiconductor, comprising: providing means for applying a magnetic field to a single molten semiconductor raw material; and rotating the magnetic field applying means in synchronization with the rotation of a pre-warming crucible.