JP2864066B2 - Quartz crucible for pulling silicon single crystal and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a quartz glass crucible used for producing a silicon single crystal by melting polycrystalline silicon and a method for producing the same.

[0002]

2. Description of the Related Art In the production of silicon single crystals for semiconductors, the quality of a quartz glass crucible that melts polycrystalline silicon has a great effect on the yield of single crystal silicon to be pulled. In particular, if bubbles are contained near the inner surface of the quartz glass crucible, the bubbles are mixed into the silicon melt together with the melting of the inner surface of the crucible, are taken into the pulled silicon single crystal, and crystal defects due to crystal dislocations
(“Dislocations”). Therefore, a high quality quartz crucible that does not contain bubbles near the inner surface is desired. As a raw material for a quartz crucible, there are some known examples in which synthetic quartz is used. However, conventionally, natural quartz powder is mainly used, and a device has been devised so that bubbles are not generated near the inner surface during production.
However, at present, it is extremely difficult to produce a quartz crucible containing no bubbles.

[0003]

In the present invention, it has been found that the content of bubbles becomes substantially zero when a crystalline silica powder containing 2 to 20% by weight of amorphous silica powder is used as a raw material of a quartz crucible. Was done. The present invention has been made based on the above findings and has solved the problems of the conventional quartz crucible. It is an object of the present invention to provide a quartz crucible having an inner surface substantially free of air bubbles and a method for producing the same.

According to the present invention, at least 1
A quartz single crystal pulling quartz having a thickness of mm, which is substantially free of bubbles formed by heating and melting a crystalline silica powder containing 2 to 20% by weight of an amorphous silica powder as a raw material. A crucible is provided. Further, according to the present invention, in the production of a quartz crucible by a rotary molding method, a mold is filled with crystalline silica powder containing 2 to 20% by weight of amorphous silica powder and heated and melted, so that at least 1 mm from the inner surface. The present invention provides a method for producing a quartz crucible for pulling a silicon single crystal having a thickness substantially free of bubbles.

[0005] The bubble content near the inner surface of the quartz crucible affects the dislocation of the pulled silicon single crystal, and affects the yield of single crystallization. In the present invention, the region near the inner surface has a thickness of at least 1 mm from the inner surface. When the silicon single crystal is pulled up near the inner surface of the crucible, it is eroded by the silicon melt and melts by about 0.7 mm thick. As a result, dislocations may be generated or crystal growth may be inhibited to lower the single crystallization ratio. In the present invention, substantially not including bubbles means that the content of bubbles is 0.01 vol% or less. A bubble content of at least 1 mm from the inner surface is 0.01 vol
%, Dislocations in the silicon single crystal pulled using the crucible are reduced, and the crystallization yield is improved.

The above-mentioned quartz crucible is composed of 2 to 20% by weight, preferably 4 to 10% by weight of amorphous silica powder as a raw material.
It can be produced by using a crystalline silica powder containing the same. The amorphous silica is not particularly limited, but amorphous synthetic quartz or the like is preferable. In addition, as the crystalline silica, generally used natural quartz or crystalline synthetic quartz (cristobalite) can be used. If the content of the amorphous silica is less than 2% by weight, no significant addition effect is exhibited, and if it exceeds 20% by weight, the physical properties of the quartz crucible itself are adversely affected. When amorphous silica is added, the amorphous silica component, which tends to soften at a lower temperature than crystalline silica, softens before the crystalline silica softens,
It flows between the crystalline silica particles and expels the bubbles inside,
Alternatively, a quartz crucible substantially free of bubbles can be manufactured by filling.

The quartz crucible can be manufactured by a rotary molding method. Specifically, the amorphous silica powder is
By filling a mold with crystalline silica powder containing at most 1 to 20% by weight, preferably 4 to 10% by weight, from the inner surface of the crucible so as to have a thickness of at least 1 mm, and melting by heating.
The quartz crucible is manufactured.

[0008]

[Example] Raw material 1 made of 100% crystalline natural quartz, 100%
A raw material 2 made of crystalline synthetic quartz (cristobalite) and a raw material 3 of 100% amorphous synthetic quartz were mixed at the ratio shown in Table 1, and a quartz glass crucible was manufactured by using a rotary molding method. Table 1 shows the value of the bubble content (vol%) in a region of 1 mm thickness from the inner surface of each crucible and the single crystal yield obtained as a result of pulling a silicon single crystal using each crucible. Example 6 is a value obtained when a crucible is manufactured using 90% crystallized synthetic quartz as a raw material. Comparative examples 1 to 3 show the results when the respective raw materials were used in a conventional manner without being mixed. Comparative Example 4 is a case where a composition outside the scope of the present invention was used.

[0009]

[Table 1] Raw material composition Silicon single crystal in inner surface region Example (wt%) Bubble content yield 12 3 (vol%) (%) 1 98 2 0.01 80 2 94 6 <0.01 85 3 80 20 0.01 80 4 96 4 0.01 80 5 90 10 <0.01 83 6 (90) (10) <0.01 83 Comparative Example 1 100 0.08 78 2 100 0.15 76 3 100 0.40 58 4 70 30 0.10 77

[0010]

According to the quartz glass crucible of the present invention, since a certain area of the inner surface is substantially free of bubbles, the single crystal rate of the pulled silicon single crystal is remarkably high. In practice, the silicon single crystallization ratio of a quartz crucible is required to be 70% or more.
The quartz crucible of the present invention sufficiently meets this demand. In addition, this crucible can be easily manufactured with a proper composition of crystallized silica and amorphous silica.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C30B 1/00-35/00

Claims (2)

(57) [Claims] 1. A layer substantially free of bubbles formed by heating and melting a crystalline silica powder containing 2 to 20% by weight of amorphous silica powder as a raw material and having a thickness of at least 1 mm from the inner surface. A quartz crucible for pulling a silicon single crystal, characterized in that: 2. In the production of a quartz crucible by a rotary molding method, a mold is filled with crystalline silica powder containing 2 to 20% by weight of amorphous silica powder and melted by heating, so that the thickness is at least 1 mm from the inner surface. A method for producing a quartz crucible for pulling a silicon single crystal substantially free of bubbles.