JP2001002490A - Single crystal pulling up device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crystal pulling up device high in productivity, with which the upper part of a growing single crystal can be sufficiently cooled, thereby it becomes possible to increase the speed of pulling up. SOLUTION: Relating to the crystal pulling up device 1, a quartz crucible 4 for storing a silicon molten liquid M, a carbon susceptor 7 for receiving and supporting the quartz crucible 4, and a heater 5 for heating the silicon molten liquid M are arranged in a chamber 2. Further, a heat absorbing layer 3 consisting of a tungsten carbide coating film is formed at the upper part higher than the heater 5 of the inner surface of the chamber 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single crystal pulling apparatus for pulling a semiconductor single crystal from a semiconductor melt stored using a crucible, and more particularly to a structure of a chamber for accommodating a quartz crucible, a heater, and the like. is there.

[0002]

2. Description of the Related Art Conventionally, a Czochralski method (hereinafter referred to as a CZ method) is known as one of methods for manufacturing a semiconductor single crystal such as silicon (Si) or gallium arsenide (GaAs). The CZ method is used in the production of various semiconductor single crystals because it has a feature that a large-diameter, high-purity single crystal can be easily obtained without dislocations or with very few lattice defects.

FIG. 4 shows an example of a silicon single crystal pulling apparatus using the CZ method. This single crystal pulling apparatus 30
In this example, a quartz crucible 12 and a heater 13 are arranged in a chamber 11 which is a hollow airtight container. The quartz crucible 12 is housed in a carbon susceptor 15 supported around its axis by a shaft 14 in order to prevent softening deformation due to heat. Also, the chamber 11
Inside, a flow tube 16 is provided, which serves to rectify the inert gas supplied from above the chamber 11 and also shield heat radiation from the quartz crucible 12.

In the single crystal pulling apparatus 30, a seed crystal 17 rotatably suspended from above is immersed in a semiconductor melt 18 and pulled up to grow a semiconductor single crystal 19. Has become.

[0005]

In order to improve the productivity of a semiconductor single crystal in a crystal pulling apparatus,
There is a demand to increase the pulling speed within a range where a predetermined quality of the crystal can be maintained. For this purpose, predetermined heating is required at the solid-liquid interface between the single crystal and the melt, and the upper side of the pulled single crystal needs to be cooled. In the conventional crystal pulling apparatus having the above configuration, a metal such as stainless steel is generally used as a material of the chamber, and the chamber is configured to be water-cooled. However,
Stainless steel itself is not a material having good heat absorption, and the heat dissipated from the crystal is not absorbed so much by the chamber. Therefore, the cooling effect on the upper part of the single crystal cannot be sufficiently obtained, and there is a limit to the improvement of the pulling speed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to improve the pulling speed by sufficiently cooling the upper part of a growing single crystal, thereby improving the productivity of the crystal. It is intended to provide an upper device.

[0007]

To achieve the above object, a crystal pulling apparatus according to the present invention is provided with a quartz crucible for storing a semiconductor melt and a heater for heating the semiconductor melt in a chamber. A heat absorbing layer made of a material having a higher emissivity than the material constituting the chamber is provided on the inner surface of the chamber. The location where the heat absorbing layer is provided is desirably on the inner surface of the chamber above the installation location of the heater.

In the case of the conventional crystal pulling apparatus, since the metal such as stainless steel constituting the chamber is a material having poor heat absorption, the cooling effect on the upper part of the single crystal cannot be sufficiently obtained. In contrast, the crystal pulling apparatus of the present invention is provided with a heat absorbing layer made of a material having a higher emissivity than the material constituting the chamber on the inner surface of the chamber. The single crystal is easily absorbed by the heat absorbing layer, and the single crystal is sufficiently cooled. As a result, the single crystal pulling speed can be increased, and a crystal pulling apparatus with high productivity can be realized.

Furthermore, the inner surface of the chamber is less likely to change in quality than when the surface of the stainless steel is exposed, and heat is radiated from the crystal in a stable manner, so that the quality of the single crystal to be manufactured can be stabilized.

The "emissivity" of an object is generally defined as the ratio of the radiant emittance of thermal radiation of an object to the radiant emittance of thermal radiation of a black body at the same temperature. if,
It can be said that a material having a higher emissivity has a higher heat radiation ability or heat absorption ability. Therefore, in the present invention, by using a material having a higher emissivity than the material of the chamber as the material of the heat absorbing layer, the heat absorbing property of the inner surface of the chamber can be improved as compared with the related art.

The emissivity of stainless steel, which is a material constituting a conventional chamber, is about 0.2 to 0.3, whereas the emissivity of ceramic materials is generally higher than that of stainless steel. It is about 6 to 0.8. Therefore, as an example of a method for forming the heat absorbing layer, the heat absorbing layer can be formed by spraying a ceramic material such as tungsten carbide on the inner surface of the chamber. Of course, the material and the forming method of the heat absorbing layer of the present invention are not limited to these.

When a silicon single crystal is manufactured using a crystal pulling apparatus, it is inevitable that some silicon oxide adheres to the inner surface of the chamber. At this time, the silicon oxide does not adhere uniformly to the inner surface of the chamber, but adheres non-uniformly. Silicon oxide has an emissivity of about 0.5 to 0.8. For this reason, in the actual inner surface of the lifting chamber, regions having an emissivity of about 0.4 to 0.5 (measured at room temperature) are locally scattered on a surface having an emissivity of about 0.2 to 0.3. In this case, the heat distribution on the inner surface of the chamber becomes very uneven, and the cooling degree of the silicon single crystal also becomes uneven depending on the location. Furthermore, since the silicon oxide attachment area differs depending on the pulling device,
The degree of cooling of the crystal differs depending on the pulling device, and there is a problem that it is difficult to keep the quality constant.

From this viewpoint, it is desirable that the heat absorbing layer in the present invention is formed of a material having the same emissivity as silicon oxide. For example, when the heat absorption layer is formed of silicon oxide itself, the inner surface of the original chamber has an emissivity of about 0.5, so that even if some silicon oxide is locally scattered thereon, The influence is small, the heat distribution on the inner surface of the chamber becomes uniform, and the silicon single crystal can be cooled uniformly. In the present invention, “a material having the same emissivity as silicon oxide” specifically refers to silicon oxide, alumina (emissivity: about 0.5)
And the like.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A first embodiment of the present invention will be described below with reference to FIG. The crystal pulling apparatus according to the present embodiment is an example of an apparatus for producing, for example, a silicon single crystal, and FIG. 1 is a cross-sectional view showing the entire configuration of the crystal pulling apparatus according to the present embodiment. In the figure, reference numeral 2 denotes a chamber, 3 denotes a heat absorbing layer, 4 denotes a quartz crucible, 5 denotes a heater, and C denotes a silicon single crystal.

As shown in FIG. 1, the crystal pulling apparatus 1 of the present embodiment has a quartz crucible 4 installed in a stainless steel chamber 2 which is a hollow airtight container. The quartz crucible 4 has a shaft 6 to prevent softening deformation due to heat.
Susceptor 7 supported around its axis by
Housed within. The carbon susceptor 7 houses the quartz crucible 4 therein, and is configured to be able to move up and down together with the quartz crucible 4.

A heater 5 for heating the silicon melt M in the quartz crucible 4 is provided in the chamber 2 so as to surround the side surface of the carbon susceptor 7. A flow tube 8 is provided above the quartz crucible 4 to rectify an inert gas such as an argon gas supplied from above the chamber 2 and to shield heat radiation from the quartz crucible 4. Further, the chamber 2 itself is cooled by a cooling mechanism (not shown).

A heat absorbing layer 3 is formed on the inner surface of the chamber 2 above the heater 5 by, for example, a tungsten carbide film having a thickness of about 100 μm. This tungsten carbide film can be formed by polishing after ceramic spraying.
The thickness of the heat absorbing layer 3 is preferably 500 μm or less, more preferably about 20 μm to 300 μm. The reason is that if the thickness of the heat absorbing layer 3 is set to 20 μm or less, it may not be formed into a uniform thickness (some portions are not sprayed) depending on the state of the particles to be sprayed. In such a case, the heat conductivity of the heat absorption layer is small, so that the heat absorption layer may function as a heat insulating material, or a crack due to a difference in thermal expansion coefficient from stainless steel may occur.

When a silicon single crystal C is manufactured using the crystal pulling apparatus 1 having the above-described configuration, a silicon raw material is put into a quartz crucible 4 and heated by a heater 5 to melt the silicon raw material. A seed crystal S rotatably suspended from above is immersed in the silicon melt M and is pulled up to form a silicon single crystal C as the melt M.

In the conventional crystal pulling apparatus, the inner surface of the stainless steel chamber is exposed, whereas in the crystal pulling apparatus 1 of the present embodiment, the heat absorbing layer 3 made of tungsten carbide is formed on the inner surface of the chamber 2. Are formed. Since the emissivity of stainless steel is about 0.2 to 0.3 and the emissivity of tungsten carbide is about 0.6 to 0.8, the crystal pulling apparatus 1 of the present embodiment has a higher emissivity than a conventional apparatus. The heat dissipated from the single crystal is easily absorbed by the inner surface of the chamber 2, and the upper portion of the silicon single crystal C is sufficiently cooled. As a result, the pulling speed of the silicon single crystal C can be increased, and a crystal pulling apparatus with high productivity can be realized.

In this embodiment, the heat absorbing layer 3 is formed at a position above the heater 5 and the heat absorbing layer 3 is not formed at a position on the outer surface side of the heater 5.
Heat from the heater 5 is efficiently transmitted to the quartz crucible 4 side.

Further, since the stainless steel surface is covered with the tungsten carbide film, the inner surface of the chamber 2 is hardly deteriorated, and the heat is radiated from the silicon single crystal C stably, so that the quality of the single crystal to be manufactured is stabilized. can do.

[Second Embodiment] Hereinafter, a second embodiment of the present invention will be described.
The embodiment will be described with reference to FIG. The difference between the crystal pulling apparatus of the present embodiment and the first embodiment is that a water cooling tube is provided in the chamber. Therefore,
2, the same reference numerals are given to the same components as those in FIG. 1, and the detailed description will be omitted.

In the crystal pulling apparatus of the present embodiment, as shown in FIG. 2, a water cooling pipe 9a for cooling the pulled silicon single crystal C is provided from the top of the chamber 2 to the inside of the flow pipe 8, and The inner surface is covered with a lining layer 10.

In the crystal pulling apparatus of this embodiment,
By providing the heat absorbing layer 3 on the inner surface of the chamber 2, the upper part of the silicon single crystal C can be sufficiently cooled, and the pulling speed of the silicon single crystal C can be increased. The same effect as that of the first embodiment, which can be realized, can be obtained. Further, in the case of the present embodiment, the water-cooled tube 9a whose inner surface is covered with the lining layer 10
Is provided, the cooling efficiency of the silicon single crystal C can be further increased.

Further, the form of the water cooling tube is not limited to the shape shown in FIG. 2, but a water cooling tube 9b having a wall portion 9c extending horizontally toward the side wall of the chamber 2 as shown in FIG. It can also be used. In this case, it is preferable that the inner surface of the water cooling tube 9b is covered with the lining layer 10, and the heat absorbing layer 3 is formed on the inner surface of the wall 9c in the same manner as the inner surface of the chamber.

The technical scope of the present invention is not limited to the above embodiment, and various changes can be made without departing from the spirit of the present invention. For example, in the present embodiment, tungsten carbide is used as the material of the heat absorbing layer.
It is also possible to use materials such as silicon carbide and titanium carbide.

Further, a heat absorbing layer may be formed by coating the inner surface of the chamber with a material such as silicon oxide or alumina. In this case, since these materials have an emissivity of about 0.5, even if some silicon oxide locally adheres to the inner surface of the chamber during crystal growth, the inner surface of the chamber is The effect of the non-uniform emissivity of the silicon is small, the silicon single crystal can be cooled uniformly,
The effect of achieving more uniform crystal quality can be achieved.

[0028]

As described in detail above, in the crystal pulling apparatus of the present invention, since the heat absorbing layer is formed on the inner surface of the chamber, the crystal pulling apparatus has a smaller size than the conventional apparatus. Dissipated heat is easily absorbed by the inner surface of the chamber, and the upper portion of the single crystal is sufficiently cooled. as a result,
A single crystal pulling speed can be increased, and a crystal pulling apparatus with high productivity can be realized. In addition, since the heat radiation from the single crystal is performed stably, the crystal quality can be stabilized.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an entire configuration of a crystal pulling apparatus according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating an entire configuration of a crystal pulling apparatus according to a second embodiment of the present invention including a water cooling tube.

FIG. 3 is a sectional view showing another embodiment of the water cooling tube.

FIG. 4 is a sectional view showing an example of a conventional crystal pulling apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Crystal pulling apparatus 2 Chamber 3 Heat absorption layer 4 Quartz crucible 5 Heater

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Mark Forest 1-5-1, Otemachi, Chiyoda-ku, Tokyo Within Mitsubishi Materials Silicon Co., Ltd. (72) Inventor Kazuhiro Ikezawa 1-5, Otemachi, Chiyoda-ku, Tokyo No. 1 Inside Mitsubishi Materials Silicon Co., Ltd. (72) Inventor Hisashi Furuya 1-5-1, Otemachi, Chiyoda-ku, Tokyo F-term inside Mitsubishi Materials Silicon Co., Ltd. 4G077 AA02 BA04 CF10 EG19 EG25 PA16 5F053 AA12 AA13 BB04 BB08 BB13 BB60 DD01 DD03 FF04 GG01 RR05

Claims (3)

[Claims] 1. A single crystal pulling apparatus in which a quartz crucible for storing a semiconductor melt and a heater for heating the semiconductor melt are provided in a chamber. A single crystal pulling apparatus comprising a heat absorbing layer made of a material having a large emissivity. 2. The single crystal pulling apparatus according to claim 1, wherein the heat absorbing layer is provided on an inner surface of the chamber above the heater. 3. The single crystal pulling apparatus according to claim 1, wherein the heat absorbing layer is made of a material having an emissivity equivalent to that of silicon oxide.