JPS6033296A - Pulling device for single crystal semiconductor - Google Patents

Abstract

PURPOSE:To improve characteristics of a single crystal semiconductor and to control the diameter satisfactorily by impressing magnetic field to molten starting material in a crucible and using simultaneously a solid image pick-up element as a photodetector part of diameter control mechanism. CONSTITUTION:A solid image pick-up element e.g. a CCD image sensor 13 is provided to the outside of a measuring window 9 at the top surface of a chamber 1, and is connected electrically to a diameter control mechanism. Further, an annular superconductive coil 14 is provided to the external periphery of the chamber 1. Since magnetic field in the perpendicular direction is impressed to the molten silicon 11 by the superconductive coil 14 in this pulling device, the component in the horizontal direction of the convection is effectively retarded chiefly. As the result, characteristics in the single crystal silicon 12 are made uniform. Further, since a CCD image sensor 13 is used, influence of the magnetic field is excluded. Moreover, the control of diameter of single crystal silicon 12 is satisfactorily performed even at time of neck down or in vibration of the single crystal silicon 12 due to its superior resolution.

Description

[Detailed description of the invention] The present invention relates to improvements in single crystal semiconductor pulling equipment.

Single crystal semiconductors used in the manufacture of semiconductor devices are mainly manufactured by the Czochralski method (cZ method). Conventionally, a single crystal semiconductor pulling apparatus as shown in FIG. 1 has been used in this cz 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, and a graphite protector 3 is supported on the support rod 2 to protect the quartz crucible 4. A cylindrical heater 5 and a heat insulating cylinder 6 are sequentially arranged around the outer periphery of the protector 3. Further, a chain 7, for example, is suspended from the upper opening of the chamber 1, and holds a seed crystal 8. For example, a measurement window 9 is provided at a predetermined position on the upper surface of the chamber 1, and outside the measurement window 9, for example, an ITV camera 10 and the ITV camera 1 are provided.
A diameter control groove is provided which is electrically connected to 0.

In the CZ method using the above-mentioned pulling device, for example, when manufacturing single crystal silicon, a silicon raw material is put into a crucible 4, the silicon raw material is melted by a heater 5, and a seed crystal 8 is added to this molten silicon 11. Soak the crucible 4 and crystal 8 in opposite directions while pulling up the chain 7.
From this, the single crystal silicon 12 is pulled up. At this time, the position of the bright line seen on the surface of the liquid side of the solid-liquid interface is detected from the light receiving part l of the diameter control mechanism provided outside the measurement window 9, and the diameter control mechanism The diameter of the single crystal silicon 12 is controlled by performing feedback f (If control) to change the pulling speed or heater temperature.

However, because the resolution of the light-receiving parts of conventional ITV cameras and the like is poor, measurement accuracy decreases due to shaking of the single-crystal silicon 12, and measurement is difficult during operations to reduce the diameter of the crystal at the initial stage of pulling (so-called neck-down). Furthermore, there was a drawback that noise increased when high frequencies were used in the surrounding area.

On the other hand, in conventional pulling equipment, forced convection and thermal convection occur in the molten silicon II in the crucible 4 during pulling of single crystal silicon, and the temperature distribution of the molten silicon 11 near the crystal growth interface, impurity concentration, and oxygen The concentration is non-uniform. For this reason, the pulled single crystal silicon 1
In No. 2, the uniformity of resistivity distribution and oxygen concentration distribution was poor in both the growth direction and the radial direction, making it difficult to supply high-quality wafers for VLSI.

Therefore, attempts have been made to suppress convection by applying a magnetic field to molten silicon in the horizontal or vertical direction, thereby making the resistivity distribution and oxygen concentration distribution of single crystal silicon uniform.

However, in the ITV camera used as the light receiving part of the conventional diameter control mechanism, an image pickup tube is used and the movement of electrons in vacuum is involved, so applying a magnetic field to molten silicon can eliminate the effect. As a result, the image pickup tube did not operate properly, making it difficult to control the diameter of the tube.The effect was especially strong in a strong magnetic field, making diameter control almost impossible.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a single-crystal semiconductor pulling device that can improve the physical properties of a single-crystal semiconductor and also can control the diameter well.゛That is, the single crystal semiconductor pulling apparatus of the present invention is.

The present invention is characterized in that a means for applying a magnetic field to the molten semiconductor raw material in the crucible is provided, and a solid-state image sensor is used as the light receiving section of the diameter control mechanism.

In this way, a solid-state image sensor (
For example, if a CCD image sensor (CCD image sensor) is used, the diameter of the single crystal semiconductor can be well controlled because it is not affected by the magnetic field.

Hereinafter, embodiments of the present invention will be described with reference to FIG. Note that the same members as those of the conventional lifting device shown in FIG. 1 are designated by the same numbers and their explanations will be omitted.

In the figure, 13 is a CCD image sensor provided outside the measurement window 9 on the upper surface of the chamber 1, and this CCD image sensor 13 is electrically connected to a diameter control mechanism (not shown). Also.

A ring-shaped superconducting coil 14 is arranged around the outer periphery of the chamber 1 . This superconducting coil 14 is supplied with liquid helium from a liquid helium refrigerator (not shown).

The pulling of single crystal silicon 12 using this pulling device is as follows:
Except for applying a magnetic field to the molten silicon II by the superconducting coil 14 and passing a substantially direct current to the heater 5, the operation is substantially the same as in the conventional apparatus.

According to the above-mentioned pulling device, since the superconducting coil 14 applies a vertical magnetic field to the molten silicon 11, it is possible to effectively suppress mainly the horizontal component of convection. As a result, the physical properties within the single crystal silicon 12 can be made uniform.

In addition, the CCD image sensor 13 is used as the light receiving part of the diameter control mechanism, so it is not affected by magnetic fields.
Since the resolution is good, the diameter of the single crystal silicon 12 can be well controlled even when the neck is down or when the single crystal silicon 12 shakes.

In the above embodiment, a ring-shaped superconducting coil was used as a means for applying a magnetic field to molten silicon, but the present invention is not limited to this. For example, two tF coils were used at positions corresponding to both sides of the crucible.
A horizontal magnetic field may be applied to the molten silicon by arranging the ah stones so that the poles of different polarities correspond to each other.

Furthermore, although the above description has been made regarding the case of manufacturing single crystal silicon, it goes without saying that the present invention is not limited to this and can be similarly applied to the case of manufacturing single crystals such as GaAs.

As detailed above, the single crystal semiconductor pulling apparatus of the present invention has remarkable effects such as being able to manufacture high quality single crystal semiconductors with uniform physical properties and well-controlled diameters. It is something.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional single crystal semiconductor pulling apparatus, and FIG. 2 is a sectional view of a single crystal semiconductor pulling apparatus in an embodiment of the present invention. I... Chamber, 2... Support rod, 3... Protector, 4 Crucible, 5... Heater, 6... Heat retention cylinder, 7...
・Chain, 8... Seed crystal, 9... Measuring window, 11
... Molten silicon, 12 ... Single crystal silicon, 13
...COD image sensor, 14...superconducting coil. Applicant's agent Patent attorney Takehiko Suzue Figure 1

Claims (1)

[Claims] In an apparatus for manufacturing a single crystal semiconductor by rotatably supporting a crucible in a chamber, dipping a seed crystal rotatably suspended from above the crucible into the molten semiconductor raw material in the crucible, and pulling up the seed crystal, A single-crystal semiconductor pulling apparatus characterized in that a means for applying a magnetic field to the molten semiconductor raw material in the crucible is provided, and a solid-state image sensor is used as a light receiving section of a diameter control mechanism.