JPH05279175A - Device for lifting semiconductor single crystal - Google Patents

Abstract

PURPOSE:To provide the single crystal-lifting device capable of improving the thermal stability of a lifting shaft and capable of stably forming the semiconductor single crystal having a stable thick diameter over a long period. CONSTITUTION:The lifting shaft 5 is composed of the connected member of an upper shaft 15a with a lower shaft 15b, and the connected member is placed in a protecting cylinder. Preferably, the upper shaft is detachably attached to the lower shaft. Further, the lower shaft is preferably constituted so as to attain a diameter larger than that of the upper shaft.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor single crystal manufacturing apparatus for manufacturing a homogeneous semiconductor single crystal from a raw material melt in a crucible.

[0002]

2. Description of the Related Art A CZ (Czochralski pulling) method for growing a columnar crystal from a raw material melt in a crucible is widely used for growing a semiconductor single crystal.

Usually, in growing a semiconductor single crystal, in order to maintain high quality of the grown single crystal, a crucible is installed in a chamber evacuated to a predetermined vacuum degree, and a raw material melt in the crucible is placed. The method of pulling up the crystal while growing it is adopted.

Such a device is divided into a shaft system in which a shaft is pulled up by the pulling method and a wire system in which a wire is wound.

In order to control the diameter of the pulled single crystal, the pulling speed must be controlled. Among these, the shaft method uses an optical control method for detecting the diameter of the pulled single crystal using a camera, and a weight sensor. There is a weight type control method in which the weight of the pulled single crystal is detected by using.

For example, a conventional optical semiconductor single crystal growing apparatus using an optical control method is one in which a diameter of a pulled single crystal is detected by using a camera 11 as shown in FIG. A raw material 3 housed in a quartz crucible 2 installed in a chamber 1 held below is heated and melted by a heater 4, and a seed crystal attached to a pulling shaft 5 is dipped in this melt, and while rotating this. It is configured to pull up to grow a single crystal (not shown).
Here, in the heater 4, the quartz crucible 2 is further mounted in the graphite crucible 9 supported by the crucible receiver 8 mounted on the pedestal (crucible support base) 7, and the silicon raw material is melted inside the quartz crucible 2. It is designed to be held as a raw material melt. In this optical control method, the pulling shaft 5 is attached to the pulling device main body via the pulling shaft guide, and the pulling shaft 5 is composed of a thin round bar having a single diameter in the length direction and its tip end. A mounting portion of a seed crystal 17 called a seed adapter 16 is connected to the. In addition, there is a seed adapter which is composed of two or more different parts. However, since this is for optically detecting the diameter of the pulled single crystal, there is a problem that the position of the camera is limited, the size of the apparatus becomes large, and an error due to reflection is likely to occur.

On the other hand, in the weight type diameter control system, the weight sensor 12 is used to detect the weight of the pulled single crystal as shown in FIG. 6, and there is no problem as described above. However, in recent years, the diameter of the pulled single crystal is becoming thicker, and in such a weight type diameter control system, the pulling shaft receives much radiant heat from the melt 3 in the quartz crucible 2 and the heater 14 below, Since the pulling shaft 5 is composed of a single round bar, this heat is also transmitted to the upper drive unit, and it becomes impossible to maintain the mechanical accuracy of the shaft for a long time, making it difficult to manufacture a semiconductor single crystal. The problem of becoming stable is emerging. Here, 10 is a heat insulating cylinder.

It is also possible to make the pulling shaft thicker in the lengthwise direction in order to provide the pulling shaft with thermal durability. In this case, however, the weight of the pulling drive shaft increases remarkably, which facilitates maintenance. There was a problem that it could not be done.

Therefore, in order to solve this problem, a wire system is often used when pulling up a large-diameter semiconductor single crystal. However, the wire method has a problem that a positional deviation easily occurs.

[0010]

When pulling a semiconductor single crystal having a large diameter as described above, the weight type diameter control system
Since the pulling shaft is a single round bar, it receives a lot of radiant heat from the molten liquid in the quartz crucible and the heater, and this heat is also transmitted to the upper drive part, maintaining the mechanical accuracy of the shaft for a long time. However, there is a problem that the production of semiconductor single crystals becomes unstable. Further, in order to pull up a semiconductor single crystal having a large diameter, it is necessary to increase the mechanical strength and the thermal strength of the pulling shaft, but if it is thick, there is a problem that the weight increases and maintenance becomes difficult.

The present invention has been made in view of the above circumstances, and is a single crystal that improves the thermal stability of the pulling shaft, is easy to maintain, and can form a large diameter semiconductor single crystal that is stable for a long period of time. An object is to provide a pulling device.

[0012]

Therefore, in the present invention, the pulling shaft is composed of a connecting body of the upper shaft and the lower shaft, and the connecting portion is located in the protective cylinder.

Preferably, the upper shaft and the lower shaft are detachably mounted. More preferably, the lower shaft is constructed to have a larger diameter than the upper shaft.

[0014]

According to the above construction, since the pulling shaft is composed of the connecting body of the upper shaft and the lower shaft, heat is temporarily cut off at this connecting portion.
Heat conduction to the upper shaft is small. Therefore, deterioration due to heat is prevented.

Further, by detachably mounting the upper shaft and the lower shaft of the pulling shaft, if the lower shaft deteriorates due to heat radiation, only the lower shaft needs to be replaced, and depending on the diameter of the pulling single crystal. If the thickness or the material of the lower shaft is changed, the thermal stability of the pulling shaft can be improved.

Further, if the pulling shaft is composed of a connected body of an upper shaft and a lower shaft having a diameter larger than that of the upper shaft, it receives heat radiation, so that only the lower shaft which is required to have thermal durability is used. If the diameter is increased, it is possible to reduce the increase in weight and provide durability. Further, by reducing the weight of the pulling shaft itself, the required range of the detection accuracy of the weight sensor for detecting the weight of the pulling single crystal supported by the pulling shaft for controlling the diameter of the pulling single crystal is reduced.

[0017]

Embodiments of the present invention will now be described in detail with reference to the drawings.

The single crystal growing apparatus of the first embodiment of the present invention is, as shown in the sectional view of FIG. 1, an upper shaft 15a having a single crystal pulling shaft 15 made of a stainless steel rod, and a diameter larger than this upper shaft. And a lower shaft 15b made of a stainless steel rod so that these connecting portions R are located above the lower end of the stainless steel heat insulating cylinder 10 and all portions exposed on the crucible are large diameter portions. It is characterized by being configured.

A seed adapter 16 made of carbon is installed below the lower shaft 15b to support a seed crystal 17.

The other parts are formed in the same manner as the conventional apparatus shown in FIG. 6, and the single crystal raw material 3 contained in the quartz crucible 2 in the chamber 1 held under reduced pressure is heated and melted by the heater 4. Then, the seed crystal attached to the pulling shaft 5 is immersed in this melt, and the single crystal 6 is grown by pulling the seed crystal upward while rotating it.

Next, a method for growing a silicon single crystal using this single crystal manufacturing apparatus will be described.

First, the chamber 1 is evacuated to 10 ^-2.
-10 ^-3 Torr.

Argon gas is introduced into the chamber through a gas inlet (not shown), and the chamber 1
Turn on the heater 4 for heating the quartz crucible 2 inside,
A raw material melt is obtained.

Then, a seed crystal is dipped in this raw material melt, the weight of the growing single crystal including the pulling axis is measured by the weight sensor 12, and the single crystal is pulled up by the pulling axis 15 while adjusting the pulling rate. Are to be trained.

By using this apparatus, it is possible to obtain a good crystal which is stable and reliable for a long period of time.

Furthermore, the present invention is not limited to the above-mentioned embodiment, but can be applied to various application examples, for example, growth of single crystals other than silicon.

Next, as a second embodiment of the present invention, as shown in FIG. 2, the upper shaft 25a of the pulling shaft and the lower shaft 25b having a large diameter are detachably attached by the attachment fittings 25c. It is a feature. In this way, the lower shaft 25
If b deteriorates, only the lower shaft needs to be replaced,
Further, if the thickness or material of the lower shaft is changed according to the diameter of the pulled single crystal, the thermal stability of the pulled shaft can be improved.

As a third embodiment of the present invention, as shown in FIG. 3, an upper shaft 35a made of stainless steel and a lower shaft 35b having the same diameter may be connected.
In this case, although they have the same diameter and are made of the same material, the heat is temporarily cut off at the connecting interface as compared with the case where they are integrally formed, so that the deterioration of the upper shaft can be greatly reduced.

In the third embodiment, the same material is used, but the lower shaft may be made of a material having higher heat resistance.

As a fourth embodiment of the present invention, as shown in FIG. 4, the upper shaft 45a and the lower shaft 45b may be connected via a connecting member 45C made of a heat insulating material.

[0031]

As described above, according to the present invention, the argon gas introduced from the lower side of the chamber forms a rising flow from the lower side of the main heater toward the upper end portion, and the deposition of silicon oxide It is possible to extend the life of the carbon in-furnace product, which is a consumable item, and improve the manufacturing yield of the pulled single crystal.

[Brief description of drawings]

FIG. 1 is a sectional view of a single crystal manufacturing apparatus according to a first embodiment of the present invention.

FIG. 2 is a main part diagram of a single crystal manufacturing apparatus according to a second embodiment of the present invention.

FIG. 3 is a main part diagram of a single crystal manufacturing apparatus according to a third embodiment of the present invention.

FIG. 4 is a main part diagram of a single crystal manufacturing apparatus according to a fourth embodiment of the present invention.

FIG. 5 is a sectional view of a conventional single crystal manufacturing apparatus.

FIG. 6 is a sectional view of a conventional single crystal manufacturing apparatus.

[Explanation of symbols]

 1 chamber 2 quartz crucible 3 melt 4 heater 5 pulling shaft 7 pedestal 8 crucible receiver 9 graphite crucible 10 heat retaining cylinder 11 camera 12 weight sensor 15a upper shaft 15b lower shaft 16 seed adapter 17 seed crystal 25a upper shaft 25b lower shaft 25c connecting fitting 35a Upper shaft 35b Lower shaft 45a Upper shaft 45b Lower shaft 45c Connecting fitting

Claims (3)

[Claims] 1. A chamber provided with a crucible for filling a raw material, a heating heater installed in the vicinity of the crucible in the vicinity of the crucible and melting the raw material in the crucible to form a raw material melt, and the crucible. A pulling part for pulling a single crystal by immersing a seed crystal attached to the end of the pulling shaft in the raw material melt, a weight sensor attached to the pulling shaft for measuring the weight of the pulling single crystal, and the weight sensor In the semiconductor single crystal manufacturing apparatus having a control unit that controls the pulling rate based on the measured value of the semiconductor single crystal, the pulling shaft is composed of a connected body of an upper shaft and a lower shaft. Lifting device. 2. The semiconductor single crystal pulling apparatus according to claim 1, wherein the upper shaft and the lower shaft are detachably mounted. 3. The semiconductor single crystal pulling apparatus according to claim 1, wherein the pulling shaft is composed of a connected body of an upper shaft and a lower shaft having a diameter larger than that of the upper shaft.