JPH0543381A - Apparatus for growing single crystal by molten layer process and method for controlling oxygen concentration in single crystal using the apparatus - Google Patents

Abstract

PURPOSE:To increase the oxygen content of a grown single crystal while suppressing the segregation of impurities by a moltenlayer process. CONSTITUTION:The objective single crystal growing apparatus 10 for molten- layer process is provided with a crucible 11 containing a raw material, a heater 14 placed around the crucible 11, etc. The surface of the molten liquid 17 is almost completely covered with a ring-shaped cover 21 placed near and above the surface of the molten liquid 17 in the crucible 11. An introducing part 20 having inverted truncated conical shape is expanded upward from the inner edge of the ring-shaped cover 21. A flow-straightening jig 19 composed of the cover 21 and the introducing part 20 is placed above the crucible 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single crystal growth apparatus for a melt layer method and a method for controlling oxygen concentration in a single crystal using the apparatus, and more particularly to a crucible containing raw materials and a crucible surrounding the crucible. And a method for controlling the oxygen concentration in a single crystal using the apparatus, the apparatus for growing a single crystal using a melted layer method.

[0002]

2. Description of the Related Art There are various methods for growing a single crystal, but a silicon single crystal used for a material such as a semiconductor is
It is produced by a pulling method called Czochralski method (CZ method) or float zone method.

In the CZ method, a growth furnace 40 as shown in FIG. 4 is used. The growth furnace 40 is mainly composed of a main chamber 41 and a pull chamber 42, and a gate valve 43 is interposed between the main chamber 41 and the pull chamber 42. A crucible 31 filled with a silicon melt 37 is provided in the main chamber 41, and a heater 34 is provided near the outer periphery of the crucible 31.
On the other hand, a wire 35 for pulling up the single crystal 36 is hung from above the pull chamber 42. In addition, the main chamber 41 and the pull chamber 42
A gas supply pipe 44 for supplying an argon gas or the like is connected to the upper part of each, and a suction pipe 45 connected to a vacuum pump (not shown) is fixed to the lower part of the main chamber 41.

FIG. 5 is a schematic enlarged sectional view of an essential part of a single crystal growth apparatus used in the conventional CZ method, in which 31 is a crucible. The crucible 31 includes a bottomed cylindrical quartz inner layer container 32 and a bottomed cylindrical graphite outer layer container 33 fitted to the outside of the inner layer container 32. A heater 34 is arranged in a concentric cylindrical shape. The crucible 31 is filled with a melt 37 of the raw material melted by the heater 34, a pulling shaft 35 is arranged on the central axis of the crucible 31, and a seed crystal ( (Not shown) is attached.

When the single crystal 36 is grown, the seed crystal is brought into contact with the surface of the melt 37 and the pulling shaft 35 is pulled up to grow the single crystal formed by solidifying the melt 37. ing.

When a semiconductor single crystal is grown by this method, an impurity element is often added to the melt 37 before the single crystal 36 is pulled up. At this time, a phenomenon occurs in which the added impurities segregate along the crystal growth direction of the single crystal 36, and as a result, a single crystal having uniform electrical characteristics in the crystal growth direction cannot be obtained, and the yield is low. was there.

As a method for growing a crystal while suppressing the segregation of the impurities, there is a melt layer method. The melt layer method is shown in Fig. 6.
As shown in FIG. 5, by melting only the upper portion of the raw material in the crucible 11 configured as shown in FIG. 5 with the heater 14, the molten liquid layer 17 is formed in the upper portion and the solid layer 18 is formed in the lower portion. Once formed, the single crystal 16 is grown.

When operating the apparatus constructed as described above, the lower end of the seed crystal (not shown) is immersed in the molten liquid layer 17 while melting the solid layer 18 and pulled up while rotating the pulling shaft 15. As a result, the single crystal 16 having a constant impurity concentration can be grown from the lower end of the seed crystal.

Further, for example, in Japanese Patent Publication No. 57-40119, in the CZ method, the SiO adhering to the crystal and the inner wall of the crucible is prevented from being polycrystallized by returning to the melt and crystallized from the quartz crucible and the melt. A method has been proposed in which the pulling rate is improved by reducing the heat radiation to the crystal and promoting the cooling of the crystal.

[0010]

In the CZ method, a single crystal having an oxygen concentration of 12 to 17 × 10 ¹⁷ / cm ³ is usually pulled up according to the purpose of use. The oxygen concentration in the single crystals 16 and 36 is adjusted by the CZ method and the molten layer method by changing the rotation of the crucibles 11 and 31 and the rotation of the seed crystal. The supply is performed by melting out SiO _{2 from} the inner layer containers 12 and 32. Most of the oxygen supplied to the melts 17 and 37 goes out from the surfaces of the melts 17 and 37, but a part of the oxygen is taken into the single crystals 16 and 36.

However, in the above-mentioned fused layer method,
Although the yield is high, the area in which the melt 17 contacts the inner layer container 12 is reduced by the solid layer 18 to about half, and as a result, the amount of oxygen supplied to the melt 17 is reduced and it is difficult to achieve high oxygenation. There was a problem of becoming.

The present invention has been made in view of the above problems, and it is an apparatus for growing a single crystal for a melt layer method capable of increasing the oxygen content of a formed single crystal and a single crystal using the apparatus. It is an object of the present invention to provide a method for controlling the oxygen concentration in the inside.

[0013]

In order to achieve the above object, a single crystal growth apparatus for a melt layer method according to the present invention comprises a crucible containing a raw material and a heater arranged around the crucible. In a single crystal growth apparatus for a melt layer method, a ring-shaped lid body which is disposed in the vicinity of the melting liquid surface in the crucible and covers substantially the entire melting liquid surface, and an inner end portion of the lid body A rectifying jig, which is composed of an inverted frustoconical introduction portion that widens toward, is disposed above the crucible.

The method for controlling the oxygen concentration in a single crystal according to the present invention is characterized in that the above-mentioned single crystal growth apparatus for a melt layer method is used, and an inert gas is supplied to the melt surface from the introduction part.

[0015]

According to the above construction, in the single crystal growing apparatus for the melt layer method, which is equipped with the crucible containing the raw material and the heater disposed around the crucible, in the vicinity of the upper part of the melt surface in the crucible. A rectifying jig consisting of a ring-shaped lid body that is disposed in the cover and covers almost the entire melt surface, and an inverted frustoconical introduction portion that widens upward from the inner end portion of the lid body. Since it is arranged above the crucible, evaporation of SiO from the surface of the melt is suppressed and the amount of oxygen supplied to the single crystal is increased.

Further, according to the above method, since the inert gas is supplied from the introduction part to the melt surface using the single crystal growth apparatus for the melt layer method, SiO evaporates from the melt surface, and the inner wall of the crucible is evaporated. It is prevented that they adhere to the like and fall into the melt to hinder single crystallization.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the apparatus for growing a single crystal for a melt layer method and the method for controlling the oxygen concentration in a single crystal using the apparatus according to the present invention will be described below with reference to the drawings. The configuration of the single crystal growth apparatus for a melt layer method except for the rectifying jig is the same as the conventional one, and thus the description thereof is omitted.

FIG. 1 is a schematic sectional view of a single crystal growth apparatus for a melt layer method according to the present invention, in which 11 is a crucible. A pulling shaft 15 is vertically provided above the crucible 11, and a single crystal 16 is formed at a lower end of the pulling shaft 15. In addition, a rectifying jig 19 is provided around the single crystal 16.
Is disposed in the crucible 11 in the vicinity of the surface of the melt 17 in the crucible 11 and covers a substantially entire surface of the melt 17 and a ring-shaped lid 21 is provided upward from the inner end of the lid 21. The rectifying jig 19 is configured by the inverted frustoconical introduction portion 20 that widens toward the side.

The material of the rectifying jig 19 is carbon, and as shown in FIG. 2, the inner surface of the introducing portion 20 has an inverted conical shape, the outer surface has a lower cylindrical shape, and the upper portion has an inverted conical shape. The distance L between the lid 21 and the melt 17 is 15 mm, and the lid 21 has a ring shape with an inner diameter D ₁ of 190 mm and an outer diameter D ₂ of 320 mm.

Using the above-described single crystal growth apparatus 10 for the molten layer method, a silicon single crystal having a diameter of 6 inches was pulled up, and the effect of the rectifying jig 19 on the high oxygen content was examined. In this case, the heater 14 in the single crystal growth apparatus 10 for the melt layer method has a length of 150 mm, and the crucible 11 has an inner diameter D ₃ of 39 mm.
0 mm, thickness 10 mm, height 355 mm, furnace pressure 10 Torr, argon flow 30 l / mi
n (standard state 1 atm, 0 ° C), silicon raw material is 65 k
g, and the pulling rate was 1.0 mm / min, and the growth was performed, and phosphorus was used as a dopant.

The oxygen concentration distribution and resistivity distribution of the single crystal 16 thus pulled up are shown in FIG.

[0022] Figure 3 As is apparent, the oxygen concentration, 17 over the single-crystal 1000mm total length × 10 ¹⁷ /
We were able to achieve cm ^{3 and} above. This remarkably increases the oxygen concentration (15 × 10 ¹⁷ / cm ³ or less) obtained by the usual melted layer method according to the apparatus and method according to the present embodiment, and the oxygen concentration (12-17 × 10 ³ ) obtained by the CZ method. ¹⁷ / cm
It is shown that ³ ) can be realized by the melt layer method. Further, regarding the resistivity distribution, it was found that there was no problem in the range of 1: 1.3 in the total length of the single crystal of 1000 mm.

As described above, it is possible to realize the high oxygen content of the single crystal produced by the melt layer method, and the oxygen concentration range of the currently used wafer (12 to 17 × 10 ¹⁷ / cm 2).
³ ) could also be satisfied by the melt layer method. Therefore, the oxygen concentration in the single crystal can be adjusted according to the purpose of use while growing the crystal with less segregation of impurities by the melt layer method.

[0024]

As described in detail above, in the apparatus for growing a single crystal for a melt layer method according to the present invention, a melt layer including a crucible containing a raw material and a heater arranged around the crucible. In a single crystal growth apparatus for method, a ring-shaped lid is provided in the vicinity of an upper portion of the molten liquid surface in the crucible and covers substantially the entire molten liquid surface, and an upper end from an inner end portion of the lid member. Since the rectifying jig consisting of the inverted frusto-conical shaped introducing portion that is widened and arranged is disposed above the crucible, the rectifying jig suppresses evaporation of SiO from the surface of the melt, and the single crystal It is possible to increase the amount of oxygen supplied to the.

Further, in the method for controlling oxygen concentration in a single crystal according to the present invention, the above single crystal growth apparatus for the melt layer method is used, and the inert gas is supplied to the melt surface from the introduction part. It is possible to prevent SiO from evaporating from the surface of the melt and adhering to the inner wall of the crucible or the like, and causing droplets of SiO to fall into the melt and impede single crystallization.

Therefore, it is possible to grow a crystal with less segregation of impurities by the melt layer method and to realize high oxygen content of the produced single crystal, and adjust the oxygen concentration in the single crystal according to the purpose of use. can do.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a single crystal growth apparatus for a melt layer method according to the present invention.

FIG. 2 is an enlarged sectional view of an essential part for explaining the configuration of a rectifying jig.

FIG. 3 is a graph showing an oxygen concentration distribution and a resistivity distribution in a single crystal produced by using a single crystal growth apparatus for a melt layer method.

FIG. 4 is a partial cross-sectional view showing a conventional single crystal growth apparatus by the CZ method.

FIG. 5 is an enlarged cross-sectional view of a main part showing a conventional single crystal growth apparatus by the CZ method.

FIG. 6 is an enlarged cross-sectional view of a main part showing a conventional single crystal growth apparatus by a melt layer method.

[Explanation of symbols]

 10 Single Crystal Growth Device for Melt Layer Method 11 Crucible 14 Heater 17 Melt Liquid 19 Rectifying Jig 20 Introductory Part 21 Lid

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takayuki Kubo 4-53-3 Kitahama, Chuo-ku, Osaka City, Osaka Prefecture Sumitomo Metal Industries, Ltd. (72) Hideki Fujiwara 4-chome, Kitahama, Chuo-ku, Osaka City, Osaka Prefecture 5-33 Sumitomo Metal Industries, Ltd. (72) Inventor Shuichi Inami 4-53-3 Kitahama, Chuo-ku, Osaka City, Osaka Prefecture (72) Inventor Yoshihiro Akashi 1 Higashihama-cho, Amagasaki-shi, Hyogo Within Osaka Titanium Manufacturing Co., Ltd.

Claims (2)

[Claims] 1. A single crystal growth apparatus for a melt layer method, comprising a crucible containing a raw material, a heater arranged around the crucible, and the like. A rectifying jig consisting of a ring-shaped lid that covers substantially the entire melt surface and an inverted frusto-conical introduction that widens upward from the inner end of the lid is provided above the crucible. A single crystal growth apparatus for a melt layer method, characterized in that 2. A method for controlling the oxygen concentration in a single crystal, which comprises using the apparatus for growing a single crystal for a melt layer method according to claim 1 and supplying an inert gas to a melt surface from an introduction part.