JPH09249491A - Link structure between pulling-up shaft and seed crystal holder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a link structure dealt with such a problem involved in conventional ones with screwing mechanism that, in the case of heavyweight single crystal, junction strength is insufficient, and, because the junction part is liable to wear and break due to the friction on account of repeated attachment/detachment between the pulling-up shaft seed crystal holder, thread grooves are broken during pulling-up of a single crystal and there is such a risk that the seed crystal holder falls off the pulling-up shaft. SOLUTION: This link structure between a pulling-up shaft 14 and a seed crystal holder 1 is so designed that the lower part 14A of the shaft 14 is provided with a penetrated hole 14a, while the upper part of a seed crystal holder 1 is provided with another penetrated hole 1b situated on a straight line, and these holes 14a, 1b are threaded with a pin 2 so as to integrate the shaft 14 and the seed crystal holder 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seed crystal holder, and more particularly to a seed crystal holder used for growing a single crystal used as a semiconductor material.

[0002]

2. Description of the Related Art There are various methods for growing a single crystal, one of which is a pulling method represented by the Czochralski method (hereinafter referred to as the CZ method). FIG. 2 shows a conventional C
It is the cross section diagram which shows the principal part of the single crystal pulling device which is used for Z method typically, 31 in the figure shows the crucible.

The crucible 31 comprises a bottomed cylindrical quartz crucible 31a and a bottomed cylindrical graphite crucible 31b fitted to the outside of the quartz crucible 31a. 31 is supported by a support shaft 39 that rotates at a predetermined speed in the direction of the arrow in the figure. This crucible 3
On the outside of 1, a resistance heating type heater 32 and a heater 3
On the outside of 2, there is a heat insulating cylinder 4 for promoting heat transfer to the crucible 31.
2 are arranged concentrically, and the crucible 31 is filled with a single crystal raw material melt 33 melted by the heater 32.

On the central axis of the crucible 31, a pulling shaft 34 made of a pulling rod, a wire or the like is hung. A seed crystal 35 is placed at the tip of the pulling shaft 34 via the seed crystal holder 10. It can be attached.

FIG. 3 is a schematic partial sectional view showing a connection structure between the seed crystal holder 10 with the seed crystal 35 inserted therein and the pulling shaft 34.

The lower portion 35a of the seed crystal 35 is thinner than the shaft portion 35b, and a taper portion 35c is formed between the lower portion 35a and the shaft portion 35b.

The lower end portion 34A of the lifting shaft 34 has a columnar shape thinner than that of the main body portion 34B.
A thread groove 34a is formed on the side surface of the.

The seed crystal holder 10 has a tubular shape as a whole, and a tapered surface 10a is formed on the lower portion thereof. The seed crystal 35 is inserted into the lower hollow portion 11a of the seed crystal holder 10, and the lower end portion 34A of the pulling shaft 34 is attached to the upper hollow portion 11b. A taper surface 11a _-1 is formed in the middle of the hollow portion 11a, the wall surface shape of the hollow portion 11a matches the outer shape of the seed crystal 35, and the taper angle θ of the taper surface 11a _-1 is set.
₁ and the taper angle θ ₂ of the seed crystal taper portion 35c are set to the same angle. A screw groove 10b is formed on the upper side wall surface of the hollow portion 11b.

In order to hold the seed crystal 35 in the seed crystal holder 10 thus constructed and to connect the seed crystal holder 10 holding the seed crystal 35 to the pulling shaft 34, first, the seed crystal 35 is to be attached. From the top of the seed crystal holder 10, the hollow portion 11a
Insert inside. At this time, the taper portion 35c of the seed crystal 35 is joined to the taper surface 11a- ₁ formed in the hollow portion 11a, so that the seed crystal 35 does not come off from the hollow portion 11a in the seed crystal holder 10. Held in. next,
Aligning the hollow portion 11b of the seed crystal holder 10 with the lower end 34A of the pulling shaft 34, and screwing the screw groove 10a formed in the seed crystal holder 10 into the screw groove 34a formed in the pulling shaft 34. Thus, the seed crystal holder 10 is connected to the pulling shaft 34.

When the seed crystal 35 is applied to the melt 33 (about 1400 ° C.), the tip of the seed crystal holder 10 is also exposed to a considerably high temperature. It is necessary to use a material with excellent heat resistance. In addition, since metals such as iron may cause heavy metal contamination,
It is difficult to make it metallic. Therefore, the seed crystal holder 10 is generally formed of a carbon material having a high heat resistance, a carbon mesh (C / C) material, or the like.

[0011]

Generally, the lifting shaft 3
The seed crystal holder 4 and the seed crystal holder 10 are configured to be detachable as described with reference to FIG.
At the time of loading to 0, it is necessary to insert the seed crystal 35 from above the seed crystal holder 10, and every time the seed crystal 35 is replaced, the pulling shaft 34 and the seed crystal holder 10 are repeatedly attached and detached. Will be done.

However, the seed crystal holder 10 described above is used.
Is formed of a carbon material, a C / C material, or the like, it is relatively fragile, and the thread groove 10b of the seed crystal holder 10 is easily worn or chipped due to repeated attachment / detachment. Particularly recently, it has been desired to manufacture a large single crystal 36 having a diameter of about 12 inches and a weight of about 300 kg.
The load applied to 0 also tends to increase, and there is a risk that the thread groove 10b may be lost during repeated pulling of the single crystal 36 and the seed crystal holder 10 may drop from the pulling shaft 34 during pulling. there were.

The present invention has been made in view of the above problems, and even if the seed crystal holder is repeatedly attached to and detached from the pulling shaft, the connecting portion of these members is not damaged, and the single crystal can be pulled up safely. An object of the present invention is to provide a connection structure between a pulling shaft and a seed crystal holder that can be used.

[0014]

In order to achieve the above object, the connecting structure of the pulling shaft and the seed crystal holder according to the present invention has a through hole formed in the lower part of the pulling shaft, Through holes that are located on the straight line are formed in the upper portion of the seed crystal holder, and the pin body is inserted into these through holes so that the pulling shaft and the seed crystal holder are integrated. It is characterized by being.

According to the connecting structure of the pulling shaft and the seed crystal holder, when tensile stress due to a single crystal is applied to the seed crystal holder, the tensile stress is received by the shear stress acting on the pin body. Unlike the conventional case in which the tensile stress is received by the screwing surface as in the past, the thread groove is not likely to be damaged, and if the strength of the pin body is secured, the connection structure will be strong. It can be anything.

Further, the connecting structure is formed by inserting the pin body into the through hole, and has a simple structure, so that it will not be worn or chipped even if it is repeatedly attached and detached, and it will not be worn for a long time. The strength of the connecting structure can be maintained, and the manufacturing is easy and the cost can be reduced.

Therefore, in the case of pulling a large-weight single crystal, the single crystal can be safely pulled even if the pulling shaft and the seed crystal holder are repeatedly attached and detached.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a connecting structure (hereinafter, simply referred to as a connecting structure) between a pulling shaft and a seed crystal holder according to the present invention will be described below with reference to the drawings. In addition,
Components having the same functions as those of the conventional example are designated by the same reference numerals.

FIG. 1A shows a seed crystal holder 1 with a seed crystal 35 inserted and a pulling shaft 1 according to the embodiment.
4 is a schematic partial cross-sectional view showing the structure before connection with FIG. 4, and (b) is a schematic partial cross-sectional view showing the structure after connection.

The seed crystal 35 is the same as in the conventional case, and its description is omitted here.

The lower end portion 14A of the lifting shaft 14 has a columnar shape narrower than that of the main body portion 14B.
Through hole 1 having a desired diameter φ ₁ at a predetermined position of 4A
4a is formed in the horizontal direction.

The seed crystal holder 1 is in the shape of a cylinder having a tapered surface 1a at the bottom and is made of a carbon material, a C / C material or the like. Seed crystal holder 1 Lower part 1
A seed crystal 35 is inserted in 1a, and a hollow portion 11b in the upper part
The lower end portion 14A of the lifting shaft 14 is attached to this. Further, two through-holes 1b which are located in a horizontal direction and on a straight line are formed at predetermined locations on the upper portion. The diameter φ ₂ of the through hole 1b is set to be the same as the diameter φ ₁ of the through hole 14a, and the through hole 1b and the through hole 14a are on the same straight line when the lower end portion 14A is inserted into the hollow portion 11b. It is shaped like a circle. Other configurations are the same as the conventional case.

The pin body 2 is made of, for example, stainless steel, and its diameter φ ₃ is set to be slightly smaller than the diameters φ ₁ and φ ₂ of the through holes 14a and 1b. The length l ₁ of the pin body 2 is set to be equal to the upper diameter l ₂ of the seed crystal holder 1 or slightly longer than the diameter l ₂ .

The seed crystal holder 1 having the above structure is
For connection to the pulling shaft 14, first, the seed crystal 35 is inserted into the hollow portion 11a of the seed crystal holder 1, and then the lower end portion 14A of the pulling shaft 14 is inserted into the hollow portion 11b. At this time, the through hole 14a formed in the lower end portion 14A and the seed crystal holder 1
So that the through hole 1b formed in
Align both. After this, one end 2a _{-1 of the} pin body 2
Is inserted from one end 1b _-1 of the through hole 1b, and the through hole 14a
To pass through the through hole 1b to be positioned near the other end 1b _-2 . At this time, the other end 2a _-2 of the pin body 2 is located near one end 1b _-1 of the through hole 1b (Fig. 1 (b)).

According to the above connecting structure, the pulling shaft 1
4 and the seed crystal holder 1 are integrated by aligning the through holes 14a and the through holes 1b so that they are on the same straight line.
This can be easily performed by inserting the pin body 2 into these through holes 14a and 1b. Also, the lifting shaft 14
When the seed crystal holder 1 is separated from the above, it can be easily separated by pulling out the pin body 2.

Further, according to the above-described connecting structure, when the tensile stress due to the single crystal 36 is applied to the seed crystal holder 1, the tensile stress can be received by the shear stress acting on the pin body 2. Thus, unlike the case where the tensile stress is received by the threaded surface, the thread groove 1
0b is not likely to be lost, and if the strength of the pin body 2 is secured, the connection structure can be made strong.

Further, the connecting structure is formed by inserting the pin body 2 into the through hole 1b, and has a simple structure, so that it will not be worn or chipped even if it is repeatedly attached and detached, and it will not be worn for a long time. The strength of the connecting structure can be maintained, and the manufacturing is easy and the cost can be reduced.

Therefore, when pulling a large weight single crystal 36, the single crystal can be pulled safely even if the pulling shaft 14 and the seed crystal holder 1 are repeatedly attached and detached.

[0029]

[Examples and Comparative Examples] In order to investigate the tensile strength of the connection structures according to the Examples and Comparative Examples, a tensile test was conducted for 5 minutes under a load of about 300 kg, and the results of examining the occurrence of breakage or chipping are explained. To do.

In each of the examples and the comparative examples, the above test was performed 15 times on 20 samples, and the pulling shaft and the seed crystal holder were repeatedly attached and detached for each test.

In the example, the connecting structure shown in FIG. 1 was produced, and in the comparative example, the connecting structure shown in FIG. 3 was produced.
The production conditions are shown in Table 1 below.

[0032]

[Table 1]

The results of the tensile test are shown in Table 2 below.

[0034]

[Table 2]

As is clear from Table 2, in the connection structure according to the example, the connection portion was not broken or chipped even after the tensile test was repeated 15 times in all 20 samples.

On the other hand, according to the connecting structure according to the comparative example, in 5 out of 20 samples, the connecting portion was damaged before the fifth tensile test, and in 12 out of 20 samples. Caused a defect in the connecting part in the 6th to 10th tensile tests, and 11 to 15 in 3 out of 20 samples.
In the pulling test of the turn, a defect occurred in the connection part.

[Brief description of drawings]

FIG. 1 is a schematic partial cross-sectional view showing a connection structure according to an embodiment with a seed crystal inserted therein.

FIG. 2 is a schematic cross-sectional view showing a main part of a single crystal pulling apparatus used in the CZ method.

FIG. 3 is a schematic partial cross-sectional view showing a conventional connection structure in which a seed crystal is inserted.

[Explanation of symbols]

 1, 10 Seed crystal holder 1b Through hole 14, 34 Pulling shaft 14A, 34A Lower part of pulling shaft 14a Through hole 2 Pin body

Claims (1)

[Claims] 1. A pull-up shaft is provided with through-holes at the bottom thereof, while a seed-crystal holder is provided with straight-through through-holes, and pin bodies are inserted into these through-holes to thereby pull up. A structure for connecting a pulling shaft and a seed crystal holder, characterized in that the shaft and the seed crystal holder are configured to be integrated with each other.