JPH11228282A - Gas rectifying member for single crystal-pulling apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas rectifying member having high durability, capable of providing desired temperature gradient necessary for pulling single crystal and not causing pollution in a single crystal pulling apparatus and contamination of single crystal in a member for single crystal-pulling apparatus by so-called Czochralski process. SOLUTION: In this gas rectifying member 60 for single crystal-pulling apparatus 100, installed on a crucible for melting semiconductor raw material and used for rectifying inert gas which is made to flow from the upper direction into a hermetically sealed vessel body 50, a carbonaceous fiber formed product is used as a substrate and carbonized product of a thermosetting resin obtained by heating and curing and carbonizing the thermosetting resin is formed as an intermediate layer on the surface of the substrate and coat comprising a thermally decomposed carbon is formed on the surface of the intermediate layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a member for forming a single crystal pulling apparatus, and more particularly to a gas rectifying member used in a Czochralski single crystal pulling apparatus as a semiconductor material.

[0002]

2. Description of the Related Art A single crystal pulling apparatus pulls a silicon single crystal from a silicon melt in a crucible in the presence of an atmospheric gas by a so-called Czochralski method. It is known as a "single crystal manufacturing apparatus" as disclosed in JP-A-15079. The device shown in this publication, as shown in FIG.
"The rotary shaft 2 is introduced into the furnace body container 1 from below, and the crucible 4 is disposed on the end surface of the rotary shaft 2 via the mounting table 3. In addition, the heating element 5 and the heat insulation around the crucible 4 A cylinder 6 is arranged, and silicon is melted in the crucible 4 to obtain a melt 7. On the other hand, a rotating shaft 9 that slides up and down is provided above the furnace vessel 1. The rotating shaft 9 A silicon seed crystal 8 is attached to the free end of the seed crystal 8, and the rotating shaft 9 is moved above the state where the seed crystal 8 is in contact with the melt 7 in the crucible 4.
To obtain a silicon single crystal 10 below. When growing a single crystal, it is necessary to eliminate unnecessary reaction product gas so that it does not react on the liquid surfaces of the single crystal 10 and the melt 7. For this purpose, an inert gas such as argon is supplied as atmospheric gas to the single crystal and the liquid surface from above the furnace body container 1,
It is discharged from the lower part of the furnace body container 1 "(the second column of the above-mentioned publication).

[0003] In this type of single crystal pulling apparatus, in order to maintain the purity of the resulting semiconductor material, the S in the crucible is maintained.
i It is necessary to form a clean atmosphere so that impurities do not mix in the melt. For this reason, a gas rectifying member for rectifying the inert gas flowing from above is provided on the crucible for melting Si. This gas rectification prevents impurities such as SiO gas generated in the furnace at high temperature from flowing into the crucible and being mixed into the Si melt. In addition, in order to increase the temperature gradient of the Si single crystal in the pulling direction which affects the pulling speed of the Si single crystal, it also plays a role of blocking radiant heat from the Peter and the Si melt.

As described above, in order to increase the temperature gradient of a Si single crystal, it is necessary to sufficiently block radiant heat from a melt or a crucible. Further, even if the graphite material is excellent in heat resistance, it cannot sufficiently exhibit heat insulating properties. Therefore, a gas rectifying member for a single crystal pulling apparatus has been provided in which graphite is used as a base material and heat insulating material is combined to block thermal radiation. For example, JP-A-9
Japanese Patent Publication No. 183686 discloses a cylinder and a collar which coaxially surround a pulled single crystal rod. The collar is formed of a high-purity graphite material, and a heat insulating material which is superposed in a plurality of layers is provided so as to cover the upper surface of the collar. Further, the upper surface is coated with a high-purity graphite material, or the surface of the high-purity graphite material to be coated is coated with silicon carbide or the like.

[0005] However, the gas rectifying member is not only expensive due to the processing accuracy but also has a problem that the heat capacity is increased. Further, SiO gas invades from the interposed portion, and the following chemical reaction occurs, resulting in heat insulation. In some cases, the material was silicified, causing particles to be generated. SiO + 2C → SiC + CO

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a desired temperature gradient required for pulling a single crystal and to cause contamination in the single crystal pulling apparatus and contamination of the single crystal. It is an object of the present invention to provide a gas rectifying member having high durability without cost and capable of reducing costs.

[0007]

In order to solve the above-mentioned problems, means adopted in the first aspect of the present invention will be described with reference numerals used in the description of the embodiments. A gas rectifying member 60 installed on the crucible 10 to rectify the inert gas flowing from above into the sealed main body 50. The gas rectifying member 60 has a carbonaceous fiber molded body 61 as a base material. It is characterized in that a thermosetting resin carbide formed by heating and curing a thermosetting resin and then carbonizing is formed as an intermediate layer 62, and further a coating 63 made of pyrolytic carbon is formed on the surface of the intermediate layer 62. And a gas rectifying member 60 for the single crystal pulling apparatus 100.

As shown in FIG. 1, a gas rectifying member 60 according to the present invention is installed above a crucible 10 for melting a semiconductor raw material, and the entire base material is formed by a carbon fiber molding 61. It is necessary to. The reason is that such a carbonaceous fiber molded body 61 has a low thermal conductivity and a high heat insulation property. This is because it is possible to sufficiently shut off and obtain a desired temperature gradient required for pulling the single crystal.

Then, it is necessary to form an intermediate layer 62 made of a thermosetting resin carbide on the surface of the carbonaceous fiber molded body 61. The thermosetting resin carbide forming the intermediate layer 62 is formed by combining a phenol resin, a furan resin, a divinylbenzene resin, or a condensed polycyclic aromatic compound with at least one of a hydroxymethyl group and a halomethyl group. One or two or more thermosetting resins selected from a composition comprising an aromatic cross-linking agent comprising one or more aromatic rings or two or more aromatic rings and an acid catalyst are heat-cured and then carbonized. Formed. Carbonaceous fiber molded body 6
The reason why the intermediate layer 62 made of the thermosetting resin carbide is formed on the surface of the substrate 1 is that the absence of the intermediate layer 62 makes it difficult to form the pyrolytic carbon film 63, so that each fiber is coated with the pyrolytic carbon. This is because the formation of the pyrolytic carbon film 63 thereon further increases the weight, thereby increasing the heat capacity and deteriorating the heat insulation properties.

Further, a coating 6 made of pyrolytic carbon is formed on the surface of the thermosetting resin carbide formed as the intermediate layer 62.
It is necessary to form 3. The reason is that, since the surface layer of the pyrolytic carbon film 63 is dense, oxidation resistance and gas impermeability are extremely improved. This is for preventing reaction with the carbon of the curable resin carbide. On the other hand, the thermal conductivity of the surface layer of the coating 63 made of pyrolytic carbon is very low in the direction perpendicular to the pyrolytic carbon deposition surface,
This is because the original thermal conductivity of the carbonaceous fiber molded body 61 does not increase and high heat insulation is sufficiently ensured. In addition, since there is a risk of carbon falling from the thermosetting resin carbide, if these problems are prevented by the coating film 63 made of dense pyrolytic carbon, contamination in the single crystal pulling apparatus 100 and contamination of the single crystal can be prevented. Because you can do it. Further, since the surface layer of the coating 63 made of pyrolytic carbon has high density, not only the intermediate layer 62 made of a thermosetting resin carbide, but also the mechanical strength of the carbonaceous fiber molded body 61 is improved, This is because oxidation resistance and gas impermeability are also significantly improved.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to an embodiment shown in the drawings. FIG. 1 shows a single crystal pulling apparatus 100 to which a gas rectifying member 60 according to the present invention is applied.
Is shown in a vertical sectional view. This single crystal pulling apparatus 10
Numeral 0 denotes a crucible 10 for melting a semiconductor material rotatably accommodated in a hermetically sealed main body 50 around a rotary shaft. A heater 20 for heating the crucible 10 is disposed around the crucible 10. I have. A gas rectifying member 60 according to the present invention is disposed above the crucible 10.

The crucible 10 has a double structure in which a portion directly in contact with the molten semiconductor raw material is a quartz crucible 11, and the heater 20 generally employs a so-called graphite heater. , Are substantially constant in the positional relationship as shown in FIG.

As shown in FIG. 2, the gas flow regulating member 60 is formed using a carbonaceous fiber molded body 61 as a base material, and a thermosetting resin carbide is formed on the surface of the carbonaceous fiber molded body 61 as an intermediate layer 62. A coating 63 made of pyrolytic carbon is formed on the surface of the intermediate layer 62. The coating 63 made of the thermosetting resin carbide and the pyrolytic carbon forming the carbonaceous fiber molded body 61 and the intermediate layer 62 is manufactured or formed as described in detail in the following examples. (Example 1) An inverted conical carbonaceous fiber molded body 61 having a long outer diameter of 340 mm, a short outer diameter of 200 mm, a thickness of 5 mm, and a height of 350 mm was formed. In the obtained carbonaceous fiber molded body 61, as a thermosetting resin, a benzene-soluble component (average molecular weight: 3) of petroleum pitch having a softening point of 80 ° C.
40) and P-xylene glycol were mixed at a molar ratio of 1: 2, and a mixture obtained by adding 1 wt% of P-toluenesulfonic acid thereto was reacted at 130 ° C. for 40 minutes. The reaction product was melted at 130 ° C., applied to the carbon fiber molding 61, cured at 180 ° C., applied again, cured, and fired at 1900 ° C.

A carbonaceous fiber molded body 61 having an intermediate layer 62 made of a thermosetting resin carbide formed on a surface thereof is placed in a CVD furnace, and hydrogen gas is used as a carrier at a deposition temperature of 2000 ° C. and a pressure of 30 Torr. Methane gas was continuously supplied into the furnace. Thus, a coating 63 made of pyrolytic carbon having a thickness of 50 μm was formed on the entire surface of the thermosetting resin carbide.

[0015]

The single crystal pulling apparatus 100 according to the present invention.
Gas rectifying member 60 is a gas rectifying member 60 that is installed on the crucible 10 that melts the semiconductor raw material and that rectifies the inert gas that flows into the sealed main body 50 from above. Using the body 61 as a base material, a thermosetting resin carbide formed by heating and hardening a thermosetting resin on the surface of the base material is formed as an intermediate layer 62, and the surface of the intermediate layer 62 is further thermally decomposed. The carbonaceous fiber molded body 61 is provided with high heat insulation, so that a desired temperature gradient can be obtained, and a high-quality single crystal can be obtained. Further, since the coating layer 63 made of dense pyrolytic carbon is firmly formed on the intermediate layer 62, not only does not cause contamination in the sealed main body 50 and contamination of the single crystal, but also prevents silicification of the gas flow regulating member 60. Therefore, a highly durable and low-cost gas rectifying member for a single crystal pulling apparatus can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic vertical sectional view of a single crystal pulling apparatus employing a gas rectifying member according to the present invention.

FIG. 2 is a partially enlarged sectional view of the gas rectifying member.

FIG. 3 is a cross-sectional view showing a conventional silicon single crystal pulling apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 100 Single crystal pulling apparatus 10 Crucible 11 Quartz crucible 20 Heater 50 Hermetic body 60 Gas rectification member 61 Carbonaceous fiber molding 62 Intermediate layer composed of thermosetting resin carbide 63 Coating composed of pyrolytic carbon

Claims (1)

[Claims] 1. A gas rectifying member installed on a crucible for melting a semiconductor raw material for rectifying an inert gas flowing from above into a sealed main body, comprising a carbonaceous fiber molded body as a base material, A thermosetting resin carbide formed by heating and curing the thermosetting resin on the surface of the base material and forming a carbonized thermosetting resin as an intermediate layer, and further forming a coating made of pyrolytic carbon on the surface of the intermediate layer. A gas rectifying member for a single crystal pulling apparatus, characterized in that: