JPH09249493A - Seed crystal for pulling single crystal and method for pulling single crystal using the seed crystal - Google Patents

Abstract

(57) Abstract: Single crystal 1 has a large neck weight and a conventional neck diameter, which is insufficient in strength.
6 will fall. On the other hand, if the neck diameter is made thick so that the strength is sufficient, it is not possible to sufficiently eliminate the dislocations that occur when the seed crystal 15 is deposited on the melt 33. SOLUTION: A single crystal pulling seed crystal 15 having recesses 15p and 15q having a maximum depth larger than a seed crystal radius (l / 2) is formed on a side portion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seed crystal for pulling a single crystal and a method for pulling a single crystal using the seed crystal. More specifically, it is used for growing a silicon single crystal used as a semiconductor material. The present invention relates to a seed crystal for pulling a single crystal and a single crystal pulling method using the seed crystal.

[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. 4 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. Are supported by a support shaft 39 that rotates at a predetermined speed in the direction of the arrow in the figure. A resistance heating type heater 32 is provided outside the crucible 31, and a heat retaining cylinder 42 is arranged concentrically outside the heater 32 to promote heat transfer to the crucible 31. Inside the crucible 31, A single crystal raw material melt 33 melted by the heater 32 is filled.

A pulling shaft 34 made of a pulling rod or a wire is hung on the central axis of the crucible 31, and a seed chuck 34 is provided at the tip of the pulling shaft 34.
The seed crystal 35 is attached via a.

In order to pull up the single crystal 36 by the above-mentioned single crystal pulling apparatus, first, the seed crystal 35 is immersed in the melt 33, and the seed crystal 35 is made to adapt to the melt 33,
Start pulling up (hereinafter referred to as a seeding step). After that, the seed crystal 35 is thinly drawn at a predetermined pulling speed until it has a predetermined diameter, and a neck 36a of the single crystal 36 is formed (hereinafter, referred to as a necking step). Thereafter, the pulling rate is reduced to grow the single crystal 36 to a predetermined diameter,
A shoulder 36b of the single crystal 36 is formed (hereinafter referred to as a shoulder forming step). After that, a single crystal 36 having a constant diameter and a predetermined length is grown at a constant pulling rate, and the single crystal 3
6 main body (constant diameter part) 36c is formed (hereinafter,
It is referred to as a body forming process).

Regarding the purpose of performing the above-mentioned necking step,
This will be described below. In performing the seeding step, usually, the seed crystal bottom portion 35a is preheated to some extent and then applied to the melt 33, but the preheating temperature (about 1300 ° C.) is used.
A difference of 100 ° C. or more occurs between the melting point of the seed crystal 35 (about 1410 ° C.). Therefore, the melt 3
At the time of landing on 3, the dislocations due to thermal stress are introduced into the seed crystal bottom portion 35a. Since the dislocation inhibits the subsequent single crystallization, it is necessary to grow the single crystal 36 after eliminating the dislocation. Generally, the dislocations are single crystal 36
Since it grows in a direction perpendicular to the growth interface, the growth interface is made to have a downward convex shape in the necking step to eliminate the dislocation.

Generally, in the necking step,
The narrower the diameter of the neck 36a, the more downwardly convex the shape of the growth interface, and the more efficiently the dislocations can be eliminated.

[0008]

In the conventional method for pulling a single crystal described above, the diameter is about 6 inches and the weight is 80 inches.
12m in diameter to pull up the single crystal 36 of about kg
It was general to use a seed crystal 35 of about m. The diameter of the neck 36a at that time was usually set to about 2 to 3 mm so that the single crystal 36 can be pulled up safely and the dislocations can be efficiently eliminated. However, high integration of semiconductor devices in recent years,
In order to meet the demands for cost reduction and high productivity, it has been required to increase the diameter of the wafer. Recently, for example, it is desired to manufacture a single crystal 36 having a diameter of about 12 inches and a weight of about 300 kg. . In this case, with the conventional neck 36a diameter (usually about 3 mm), the neck 35a is not able to bear the weight of the pulled single crystal 36 and is damaged, and the single crystal 36 falls.

In growing the above-mentioned heavy single crystal 36, in order to prevent accidents such as dropping of the single crystal 36 and to safely pull up the single crystal 36, the silicon strength (about 16 kg) is required.
It is necessary to increase the diameter of the neck 36a to about 6 mm, calculated from f / mm ² ). However, the neck 36
When the a-diameter is reduced to this extent, the dislocations introduced during the landing of the seed crystal 35 onto the melt 33 cannot be sufficiently eliminated, and there is a problem that the yield is significantly reduced.

The present invention has been made in view of the above problems, and a seed crystal for pulling a single crystal capable of efficiently eliminating dislocations even when pulling a heavy single crystal, and a necking. It is an object of the present invention to provide a method for pulling a single crystal using the seed crystal, which does not require a step, and can pull a large-weight single crystal safely and at low cost with good yield.

[0011]

In order to achieve the above object, a seed crystal for pulling a single crystal (1) according to the present invention has a maximum depth larger than a seed crystal radius on a side portion of the seed crystal. It is characterized in that a recess having a height is formed.

According to the above seed crystal for pulling a single crystal (1), the dislocations introduced at the time of landing are characterized by their propagation directions.
Most of the propagated dislocations escape to the free surface because they propagate toward the open side surface of the recess (hereinafter referred to as the free surface) and the maximum depth of the recess is larger than the seed crystal radius. Therefore, if a tip portion including a portion where dislocations are introduced at the time of landing and a portion where the dislocations propagate (hereinafter collectively referred to as a dislocation portion) is melted into the melt at an appropriate speed up to above the recesses, Dislocation portions can be removed, and a single crystal based on a dislocation-free seed crystal can be pulled. Therefore, the dislocation-free rate of the pulled single crystal can be increased.

Further, in the seed crystal for pulling a single crystal (2) according to the present invention, in the seed crystal for pulling a single crystal (1), two or more recesses are formed at positions symmetrical with respect to the central axis of the seed crystal. It is characterized by being.

According to the seed crystal for pulling a single crystal (2), even if some of the dislocations remain on the free surface of one recess without escape, they are symmetrical with respect to the center axis of the seed crystal. Since another recess is formed at a certain position, that is, above the recess and in the direction in which the remaining dislocation propagates, the remaining dislocation is released to the free surface of the other recess. Therefore, if the tip portion including the dislocation portion is melted into the melt at an appropriate speed up to above the concave portion, the dislocation portion can be surely removed, and the single crystal based on the seed crystal without dislocation can be pulled up. It will be possible. Therefore, the dislocation-free rate of the pulled single crystal can be reliably increased.

The seed crystal (3) for pulling a single crystal according to the present invention is characterized in that the seed crystal (1) or (2) for pulling a single crystal has a seed crystal diameter of 6 mm or more.

According to the seed crystal for pulling a single crystal (3), the same effect as that of the seed crystal for pulling a single crystal (1) or (2) can be obtained, and the seed crystal diameter is 6 m.
Since it is m or more, for example, even when pulling a large-weight single crystal of 300 kg or more, the seed crystal has a sufficient strength calculated from the silicon strength (about 16 kgf / mm ² ). The single crystal can be pulled up safely without fear of accident such as falling of the single crystal due to breakage.

In the method for pulling a single crystal according to the present invention, any one of the seed crystals (1) to (3) described above is used, and the tip end portion of the seed crystal is immersed in a melt and melted up to above the recess. After that, the single crystal is pulled up without forming a neck.

According to the above single crystal pulling method, the tip of the seed crystal including the dislocation portion can be once melted up to above the concave portion to allow the dislocation to escape to the free surface of the concave portion. The single crystal can be pulled up based on the crystal. As a result, the dislocations do not propagate to the pulled single crystal, and the dislocation-free single crystal can be efficiently pulled up even if the necking step is omitted. Further, since the necking step can be omitted, there is no need to support the single crystal by a thin neck, and the seed crystal diameter is the smallest diameter for supporting the single crystal, and even if the strength of the seed crystal is sufficiently considered. Even if it is a heavy single crystal, it can be safely pulled up without fear of an accident such as dropping. Furthermore, since it is not necessary to form the neck, the seed crystal is conventionally 1
The diameter of about 2 mm can be reduced to about 6 mm, the raw material cost required for the seed crystal can be reduced, and the pulling process can be simplified.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a seed crystal for pulling a single crystal and a method for pulling a single crystal using the seed crystal according to the present invention will be described below with reference to the drawings. In addition, the same reference numerals are given to the components having the same functions as the conventional ones.

1A to 1D are schematic partial side views showing, in the order of steps, a seed crystal for pulling a single crystal according to an embodiment of the present invention and a single crystal pulling method using the seed crystal. 2 is a schematic cross-sectional view showing a state in which a single crystal is pulled by the single crystal pulling method according to the embodiment.

The seed crystal 15 has a diameter (l) of 6 mm or more, and recesses 15p and 15q having a maximum depth larger than the seed crystal radius (l / 2) are formed on the sides thereof. In order to pull up the single crystal 16 using the seed crystals 15 formed in two positions symmetrical with respect to the central axis 15x,
First, the seed crystal 15 is lowered to just above the melt 33 to preheat the seed crystal 15 (FIG. 1A). After that, seed crystal 1
5 is deposited on the surface of the melt 33 (FIG. 1 (b)). At this time, dislocations (not shown) are introduced into the tip portion 15a of the seed crystal 15 by the thermal stress acting upon the liquid deposition. After that, the seed crystal 15 is lowered at a predetermined speed, the tip portion 15a of the seed crystal 15 is immersed in the melt 33, and the concave portions 15p, 1
Melt up to above 5q (Fig. 1 (c)). In this manner, by melting the tip portion 15a of the seed crystal 15 into the seed crystal 15, the remaining portion of the seed crystal 15 can be made to be a dislocation-free portion only. After that, the necking process which has been performed conventionally is omitted and the process proceeds to the shoulder forming process, where the single crystal 16 is grown to a predetermined diameter by pulling at a predetermined pulling rate to form a shoulder 16b (FIG. 1 (d)). .
After this, the body forming process is started, and the main body 16c
(FIG. 2) is formed.

Generally, the pulling of a silicon single crystal is performed by [1
[00] direction, and the single crystal grows on the (100) plane. On the other hand, the dislocations introduced in the (100) plane are (11-
1) Easy to propagate along the surface. (100) plane and (11-
The angle formed with the 1) plane is 54.7 °, and therefore, the dislocation generated at the time of landing propagates toward the free surface direction of the recesses 15p (15q) and escapes from the free surfaces of the recesses 15p and 15q to the outside. .

According to the seed crystal 15 for pulling a single crystal as described above, the concave portions 15p and 15q having the maximum depth larger than the seed crystal radius (l / 2) are formed on the side portion of the seed crystal 15. Due to the nature of the propagation direction, the dislocations introduced at the time of landing propagate toward the free surfaces of the recesses 15p and 15q, and the maximum depth of the recesses 15p and 15q is the seed crystal radius (l
/ 2), most of the propagated dislocations escape to the free surface. Further, even when some of the dislocations remain on the free surface of one recess 15p without slipping out, the positions are symmetrical with respect to the seed crystal central axis 15x, that is, the direction in which the remaining dislocations propagate. Since the other concave portion 15q is formed in the above, the remaining dislocations will escape to the free surface of the other concave portion 15q. Therefore, if the tip portion 15a is melted into the melt 33 at an appropriate speed up to above the recess 15q, the dislocation portion can be surely removed, and the single crystal 16 based on the seed crystal 15 without dislocation can be pulled up. Is possible. Therefore, the dislocation-free rate of the pulled single crystal 16 can be reliably increased.

Further, since the seed crystal diameter (l) is 6 mm or more, for example, even when pulling a large single crystal 16 of about 300 kg, the seed crystal 15 has a silicon strength (about 16 kgf / mm ² ). Since the calculated strength is sufficient, the single crystal 16 can be pulled up safely without fear of accident such as dropping of the single crystal 16 due to breakage of the seed crystal 15.

Further, according to the single crystal pulling method using the seed crystal 15 described above, the tip portion 15a of the seed crystal 15 having the dislocation portion is once melted to dislocation dislocations 15p, 1p.
Since it can escape to the free surface of 5q, the single crystal 16 can be pulled up based on the seed crystal 15 consisting of only dislocation-free portions. Therefore, the single crystal 1 to be pulled up
Since no dislocation is introduced into 6, the necking step can be omitted. Further, since the necking step is unnecessary, there is no need to support the single crystal 16 by the thin neck 36a (FIG. 4), and the seed crystal diameter (l) is the smallest diameter for supporting the single crystal 16. Therefore, even a heavy single crystal 16 can be safely pulled up without fear of an accident such as dropping. Furthermore, since it is not necessary to form the neck 36a,
Seed crystal 15 has a diameter of 6 mm instead of 12 mm in the past.
It can be made as thin as possible, and the raw material cost required for the seed crystal can be reduced.

In this embodiment, the seed crystal 15 has two layers.
Although the case where the one recess 15p, 15q is formed is shown, the present invention is not limited to this, and in another embodiment, only one recess 15p may be formed. In yet another embodiment, three or more recesses may be formed.

[0027]

[Examples and Comparative Examples] A single crystal is pulled by a seed crystal for pulling a single crystal and a single crystal pulling method using the seed crystal according to Examples and Comparative Examples, and DF (Disloc
(ation Free) rate will be explained. In each of the Examples and Comparative Examples, a single crystal having a diameter of about 12 inches, a length of about 1000 mm, and a total weight of about 300 kg was prepared.
Raised 10 times. The DF ratio was shown by the ratio of the number of single crystals in which dislocations did not occur at all out of 10 single crystals pulled under the same conditions. The presence or absence of the dislocation can be determined by external observation, but this time, it was determined by observing the sliced single crystal with an X-ray topography.

FIGS. 3 (a) and 3 (b) are schematic partial enlarged side views shown for explaining the single crystal pulling methods according to Examples and Comparative Examples. The growth conditions common to the pulling of each single crystal are shown in Table 1 below.

[0029]

[Table 1]

<Example 1> In Example 1, the single crystal 16 was pulled in the following manner by the method shown in FIGS. 1, 2 and 3 (a) and the conditions shown in Table 1.

The seed crystal 15 has a diameter of 10 mm and a length of 180.
mm, and the side surface of the seed crystal 15 has a recess 15p,
15q was formed by grinding with a grindstone with diamond grains so that the maximum depth was 6 mm. At that time, the recess 15
p and 15q were formed so as to be symmetrical with respect to the seed crystal central axis 15x.

Using the seed crystal 15, the single crystal 16 was pulled as follows. First, the seed crystal 15 is lowered to just above the melt 33 to preheat the seed crystal 15, and then the seed crystal 15 is allowed to come in contact with the surface of the melt 33 to make the seed crystal 15 acclimatize to the melt 33. After this, 0.2 mm
The seed crystal 15 is lowered at a speed of / min, the tip 15a of the seed crystal 15 is immersed in the melt 33, and a range of about 50 mm from the tip 15a of the seed crystal 15 to above the recess 15q is melted. After that, the seed crystal 15 is pulled up at a pulling rate of about 0.3 mm / min, and the temperature of the heater 32 is adjusted to form a shoulder 16b of the single crystal 16 in a range of 100 mm below the bottom surface of the seed crystal. 1
Grow to 2 inches. After that, about 0.5 mm
The main body 16c having a diameter of 12 inches was grown at a pulling rate of / min until the length became about 1000 mm.

The DF ratio of the single crystal 16 manufactured by the method according to Example 1 was 9/10. That is,
Generation of dislocations was not confirmed at all in 9 out of 10 pulled up. The number of single crystals 16 dropped was 0/10, and no single crystals 16 dropped.

<Example 2> In Example 2, the diameter is 6 mm.
The seed crystal 15 in which the maximum depth of the recesses 15p and 15q was 3.5 mm was used, and other conditions and methods were the same as in the case of Example 1.

The DF ratio of the single crystal 16 manufactured by the method according to Example 2 was 9/10. That is,
Generation of dislocations was not confirmed at all in 9 out of 10 pulled up. The number of single crystals 16 dropped was 0/10, and no single crystals 16 dropped.

<Comparative Example 1> In Comparative Example 1, FIGS.
The single crystal 26 was pulled up by the method shown in (a) and the conditions shown in Table 1. Regarding the seed crystal 25, the recess 1
It is similar to the case of the first embodiment except that 5p and 15q are not formed, and the description thereof is omitted here.

The DF ratio of the single crystal 26 produced by the method according to Comparative Example 1 was 6/10. That is,
Generation of dislocations was not confirmed at all in 6 out of 10 pulled up. Moreover, the number of drops of the single crystal 26 was 0/10, and the single crystal 26 did not drop.

Comparative Example 2 In Comparative Example 2, the single crystal 46 was pulled by the method shown in FIGS. 3B and 4 and the conditions shown in Table 1.

The seed crystal 45 has a diameter of 12 mm and a length of 100 m.
m, in which the concave portions 15p and 15q were not formed were used. Also, when pulling the single crystal 46,
A neck 46a having a diameter of about 10 mm was formed.

In order to pull up the single crystal 46 by using the seed crystal 45, first, the seed crystal 45 is lowered to directly above the melt 33 to preheat the seed crystal 45, and then the seed crystal 45 is applied to the surface of the melt 33. The seed crystal 45 is made to come into contact with the melt 33 and is made to adapt to the melt 33. After that, the seed crystal 45 is pulled up while adjusting the temperature of the heater 32 at a speed of about 4 mm / min, and the diameter of the seed crystal 45 is about 1 mm.
A neck 46a having a length of 0 mm and a length of about 100 mm is formed.
Next, the seed crystal 45 was pulled at a pulling rate of 0.3 mm / min.
By pulling up and adjusting the temperature of the heater 32,
A shoulder 46b of the single crystal 46 was formed within a range of 100 mm below the lower end of the neck 46a, and was grown to a diameter of 12 inches. Then, at a pulling rate of 0.5 mm / min, a main body 46c having a diameter of 12 inches
Were grown to a length of 1000 mm.

The DF ratio of the single crystal 46 produced by the method according to Comparative Example 2 was 0/10. That is,
Generation of dislocations was confirmed in all the pulled single crystals 46. On the other hand, the number of drops of the single crystal 46 was 0/10, and the single crystal 46 did not drop.

Comparative Example 3 In Comparative Example 3, the single crystal 46 was pulled up by the method shown in FIGS. 3B and 4 and the conditions shown in Table 1.

The seed crystal 45 has a diameter of 12 mm and a length of 100.
mm, in which the concave portions 15p and 15q were not formed were used. Further, when pulling up the single crystal 46, a neck 46a having a diameter of about 6 mm was formed.

In order to pull up the single crystal 46 by using the seed crystal 45, first, as in the case of the comparative example 2, the seed crystal 45 is applied to the surface of the melt 33, and the seed crystal 45 is melted.
After adjusting the temperature of the heater 32 at a speed of about 4 mm / minute, the seed crystal 45 is pulled up to a diameter of about 6 m.
A neck 46a having a length of m and a length of about 100 mm is formed. Next, as in the case of Comparative Example 2, a shoulder 46b of the single crystal 46 is formed in a range of 100 mm downward from the lower end of the neck 46a and grown to a diameter of 12 inches, and then a main body having a diameter of 12 inches is formed. 46c was grown.

The DF ratio of the single crystal 46 manufactured by the method according to Comparative Example 3 was 1/10. That is,
Generation of dislocations was confirmed for 9 out of 10 pulled up. On the other hand, the number of drops of the single crystal 46 was 0/10, and the single crystal 46 did not drop.

Comparative Example 4 In Comparative Example 4, the single crystal 46 was pulled by the method shown in FIGS. 3B and 4 and the conditions shown in Table 1.

The seed crystal 45 has a diameter of 12 mm and a length of 100.
mm, in which the concave portions 15p and 15q were not formed were used. Further, when pulling up the single crystal 46, a neck 46a having a diameter of about 4 mm was formed.

In order to pull up the single crystal 46 by using the seed crystal 45, first, as in the case of Comparative Example 2, the seed crystal 45 is applied to the surface of the melt 33, and the seed crystal 45 is melted.
After adjusting the temperature of the heater 32 at a speed of about 3 mm / minute, the seed crystal 45 is pulled up to a diameter of about 4 m.
A neck 46a having a length of m and a length of about 100 mm is formed. Next, as in the case of Comparative Example 2, a shoulder 46b of the single crystal 46 is formed in a range of 100 mm downward from the lower end of the neck 46a and grown to a diameter of 12 inches, and then a main body having a diameter of 12 inches is formed. 46c was grown.

The DF ratio of the single crystal 46 produced by the method according to Comparative Example 4 was 9/10. That is,
Generation of dislocations was not confirmed at all in 9 out of 10 pulled up. On the other hand, the number of single crystals 46 dropped is 8 /
10, the single crystal 46 dropped with a high probability.

As is clear from the above results, Example 1
According to the seed crystal 15 of the present invention, since the recesses 15p and 15q having the maximum depth larger than the seed crystal radius (1/2) are formed on the side portions of the seed crystal 15, the seed crystal 15 is introduced at the time of landing. Due to the nature of the propagation direction, the dislocations 15p, 15
Most of the propagated dislocations escape to the free surface because they propagate toward the free surface of q and the maximum depth of the recesses 15p and 15q is larger than the seed crystal radius (l / 2).
In addition, some of the dislocations have one recess 15p.
Even if they remain on the free surface of the seed crystal without being completely removed, the concave portion 1
Since the other recess 15q is formed above 5p in the direction in which the remaining dislocation propagates, the other recess 1 is formed.
The remaining dislocations were released on the free surface of 5q.

According to the method of pulling the single crystal 16 according to the first embodiment, the dislocation portion is surely removed by melting the tip portion 15a into the melt 33 up to above the recess 15q at an appropriate speed. Thus, the single crystal 16 based on the dislocation-free seed crystal 15 can be pulled up. Therefore, dislocations were not introduced into the pulled single crystal 16, and the necking step could be omitted.
Further, since the necking step is unnecessary, it is not necessary to support the single crystal 16 with the thin neck 36a (FIG. 4), and the seed crystal diameter (l) is the single crystal 1
6 has the smallest diameter for supporting 6, and even if it is a heavy single crystal 16, there is no fear of an accident such as dropping,
I was able to raise safely.

Further, according to the seed crystal 15 of Example 2, since the seed crystal diameter (l) is 6 mm, sufficient strength can be obtained even when a large weight single crystal 16 of about 300 kg is pulled up. Since it has, there is little concern about accident such as dropping of the single crystal 16 due to breakage of the seed crystal 15, and the single crystal 16 can be safely
Was able to pull up. Further, the seed crystal 15 has
Since the diameter of about 2 mm was reduced to about 6 mm, the volume became about ¼, and the raw material cost required for the seed crystal 15 could be reduced.

On the other hand, according to the seed crystal 25 of Comparative Example 1, since the recesses 15p and 15q were not formed, the product yield was lower than that of the example.

Further, according to the seed crystal 45 of Comparative Example 2, dislocations were generated in all the pulled single crystals 46. It is considered that this is because the diameter of the neck 46a was as large as 10 mm and dislocations existing in the seed crystal 45 could not be completely eliminated.

Further, according to the seed crystal 45 according to Comparative Example 3, since the diameter of the neck 46a is 6 mm, even if a large single crystal 46 of about 300 kg is pulled up,
Although it was possible to safely pull up 10 of the 0 crystals without dropping them, with such a narrowing of the diameter of the neck 36a, the dislocations introduced at the time of landing of the seed crystal 35 on the melt 33 are sufficiently squeezed. However, the generation of dislocations was confirmed in 9 out of 10 of them.

Further, according to the seed crystal 45 of Comparative Example 4, since the diameter of the neck 46a was reduced to 4 mm, no dislocation was observed in 9 of the 10 pulled-up crystals, and the DF ratio was not confirmed. Was able to be improved sufficiently. However, with a diameter of 4 mm, the neck 46 is unable to withstand the weight of the pulled single crystal 46 and is damaged, and the single crystal 46 is damaged.
Dropped out of 8 out of 10.

[Brief description of drawings]

1A to 1D are schematic partial side views showing a single crystal pulling method according to an embodiment of the present invention in the order of steps.

FIG. 2 shows a method of pulling a single crystal according to an embodiment.
It is a typical sectional view showing the state where a single crystal is pulled up.

3A and 3B are schematic partially enlarged side views shown for explaining a seed crystal according to an example and a comparative example and a method for pulling a single crystal using the seed crystal.

FIG. 4 is a schematic cross-sectional view showing a main part of a single crystal pulling apparatus used in the CZ method.

[Explanation of symbols]

 15, 25, 35, 45 Seed crystal (for pulling single crystal) 15a, 25a, 35a, 45a (Seed crystal) tip portion 16, 26, 36, 46 Single crystal

Claims (4)

[Claims] 1. A seed crystal for pulling a single crystal, wherein a recess having a maximum depth larger than a seed crystal radius is formed on a side portion of the seed crystal. 2. The seed crystal for pulling a single crystal according to claim 1, wherein two or more recesses are formed at positions symmetrical with respect to the center axis of the seed crystal. 3. The seed crystal for pulling a single crystal according to claim 1, wherein the seed crystal has a diameter of 6 mm or more. 4. The seed crystal according to any one of claims 1 to 3 is used, and a neck is not formed after the tip portion of the seed crystal is immersed in a melt and melted up to above the recess. A single crystal pulling method, which comprises pulling a single crystal into