JPH05280872A - Low temperature crucible for continuous melting solution supply service with improved thermal efficiency - Google Patents

Abstract

PURPOSE:To obtain a low temperature crucible which provides a high productibity melting solution which reduces the heat transfer from a melting solution lump to a cooling crucible, receives continuous supply of a solid-state material, holding the melting solution lump and forces the melting material to flow out continuously. CONSTITUTION:A continuous melting solution supply low temperature crucible provides a cooling crucible main body 1 having an opening designed to force a melting solution to flow down to the lower part, a coil 4 laid out around the outer periphery and a ceramic pipeline 2 which is laid out along the inner wall of the cooling crucible main body 1 and provided with a melting solution flow outlet 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crucible used for continuous melting of materials such as metals, semiconductors and ceramics and for continuous outflow of molten materials.

[0002]

2. Description of the Related Art Usually, melting of metal or the like is carried out using a container such as a crucible having a refractory property equipped with an induction heating device, but contamination by inclusions such as refractory cannot be avoided. , It was difficult to produce high-purity materials.

In recent years, as a melting method for obtaining a molten material requiring high purity, a technique of melting the material in a non-contact manner with a crucible wall by induction melting using a low temperature crucible (cold crucible) has been widely reported. .. This low temperature crucible technology is particularly suitable for induction melting of materials such as metals in the high and intermediate frequency regions.

In this low temperature crucible, the crucible wall is constructed by connecting a plurality of segments in an annular shape, and each segment is generally made of copper having a hollow portion through which cooling water is passed. The material to be melted is put in this crucible, and an eddy current is generated in the material in the crucible by passing a high-frequency or intermediate-frequency current through the induction coil arranged on the outer periphery of the crucible, and the eddy current loss causes The material can be melted. At the same time, by the electromagnetic force generated by the eddy current generated on the crucible surface and the eddy current generated on the molten material surface, the melt in the crucible is prevented from coming into contact with the crucible wall and the wall below the crucible is squeezed. By raising the inclusions inside, a highly pure material can be obtained.

A melting and crystallization method using this low temperature crucible technology is disclosed in Japanese Patent Laid-Open No. 60-2876, and a continuous casting method of silicon using this low temperature crucible technology is Japanese Patent Laid-Open No. 64-53732. It is disclosed in the publication.

[0006]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The method disclosed in Japanese Unexamined Patent Application Publication No. 87632/1989 is a method of continuously taking out a material melted in a low temperature crucible from the crucible while solidifying the material, and the method disclosed in Japanese Unexamined Patent Application Publication No. 64-53732 discloses a method of lowering the crucible. Although it is a continuous casting method of solidifying in, in these methods, since it is difficult to continuously melt and flow out a suitable amount continuously in a molten state,
Since there is no choice but to perform batch-type operation, continuous operation is not possible and there is a problem of low productivity.

Therefore, the present inventor holds a certain amount of molten liquid (molten liquid lump) in the low temperature crucible in balance between the surface tension and the supporting force of electromagnetic force generated from the coil and gravity.
Solid material is continuously or intermittently supplied into the crucible,
A method has been devised in which an amount of molten material corresponding to this supply amount flows out from an outlet provided in the lower part of the crucible.

However, this method has a drawback in that the heat loss due to the heat transfer from the molten liquid mass to the cooling crucible body is large and the power consumption of the coil is very large. When the amount of heat transferred from the melt mass to the cooling crucible is large and a large amount of heat is supplied from the coil to the melt mass, the temperature of the melt mass easily fluctuates, and the effluent from the cooling crucible is received. In many cases, it has an unfavorable influence on the process such as pulling of the single crystal.

It is an object of the present invention that heat transfer from a molten liquid mass to a cooling crucible body is small and a solid material is continuously supplied while the molten liquid mass is held to continuously flow out the molten material with high productivity. It is to provide a low temperature crucible.

[0010]

The first aspect of the present invention is as follows.
A cooling crucible body having an opening for letting the melt flow down, a coil arranged on the outer periphery of the cooling crucible body, a shape along the inner wall of the cooling crucible body, and a melt flow to the lower portion arranged along the inner wall. A low temperature crucible for continuous melt supply including a ceramic tube having an outlet.

A second aspect of the present invention is the first aspect in which a gap of 1 to 5 mm is provided between the cooling crucible body and the ceramic tube.
It is a low temperature crucible of the embodiment.

In a third aspect of the present invention, a low thermal conductivity ceramic coating material is applied to at least one of the inner wall of the cooling crucible body and the outer wall of the ceramic tube.
Or, the low temperature crucible according to the second aspect.

A fourth aspect of the present invention is the low temperature crucible of the first, second or third aspect in which a heat insulating material is placed inside the cooling crucible body and the ceramic tube.

Any material may be used as the material of the cooling crucible body as long as it has good thermal conductivity and generates an eddy current in the material when a high frequency or intermediate frequency current is applied to the induction coil outside thereof. Copper is most preferred because it is easily available and easily processed.

Examples of the ceramic used for the ceramic tube include quartz, alumina, mullite, zirconia, magnesia and the like.

When a gap is provided between the cooling crucible body and the ceramic tube, it is preferably 1 to 5 mm. If it is less than 1 mm, the improvement of the heat insulation effect is small, and if it is more than 5 mm, the distance from the coil to the molten mass becomes large and the eddy current in the molten mass induced by the electromagnetic force becomes small, which conversely reduces the thermal efficiency. .. It is preferable to introduce air into this gap to form an air insulating layer.

The low thermal conductivity ceramic coating material applied to at least one of the inner wall of the cooling crucible body and the outer wall of the ceramic tube includes silica, alumina, zirconia, titania, mullite, alumina-chromia and the like and ceramics thereof. Examples include cermet materials.

As the heat insulating material, silica, alumina,
Examples thereof include fiber-based heat insulating materials containing zirconia as a main component.

FIG. 1 shows a sectional view of an example of the first aspect. Other forms of shape or construction will be readily apparent. In FIG. 1, 1 is a cooling crucible body, 2 is a ceramic tube, 3 is a lower melt outlet of the ceramic tube, 4 is a coil, 5 is a power supply line, 6 is a cooling water flow path, 7 is a melt mass,
Reference numeral 8 is a solid material for melting, and 9 is an effluent.

[0020]

【Example】

Example 1 Using a low temperature crucible (Example 1) as shown in FIG. 1, 10 g of dopant-containing silicon (specific resistance 0.01 Ω · cm)
And 50 g of high-purity silicon of Eleven 9 was induction-heated to form a molten silicon liquid mass. When the power of 40 KW was applied to the coil, solid high-purity silicon (Eleven 9) particles were charged and the molten liquid was allowed to flow down, and the maximum value of the input / flow amount was 120 g / min.

The material of the cooling crucible of the low temperature crucible was copper, and the material of the ceramic tube was quartz.

Example 2 An experiment was conducted in the same manner as in Example 1 on a low temperature crucible having the same shape, structure and material as those of Example 1, but different in that the gap between the cooling crucible body and the ceramic body was 2 mm. It was The maximum value of silicon input / flow rate was 125 g / min.

Example 3 A low temperature crucible having the same shape, structure and material as in Example 1 but different in that zirconia was applied as a low thermal conductive ceramic coating material to the inner wall surface of the cooling crucible body. An experiment was conducted in the same manner. The maximum amount of silicon charged / flowed was 130 g / min.

Example 4 A low temperature crucible having the same shape, structure and material as in Example 1 but having zirconia applied as a low thermal conductive ceramic coating material on the outer wall surface of the ceramic tube was the same as in Example 1. The experiment was carried out. The maximum amount of silicon charged / flowed was 130 g / min.

Example 5 The shape, structure and material were the same as in Example 1, but the gap between the cooling crucible and the ceramic tube was 2 mm, and the density was 0.
An experiment was conducted in the same manner as in Example 1 with respect to a low temperature crucible which was different in that it was filled with 7 g / cm ³ of a zirconia heat insulating material felt. The maximum amount of silicon input / flow is 13
It was 5 g / min.

Comparative Example 1 A low temperature crucible having the same shape, structure and material as in Example 1 except that a ceramic tube was not used was tested in the same manner as in Example 1. Maximum amount of silicon input / flow is 1
It was 00 g / min.

[0027]

EFFECTS OF THE INVENTION According to the low temperature crucible of the present invention, a molten liquid having a high productivity is continuously supplied by continuously feeding the solid material while holding the molten liquid mass in the crucible. Manufacturing method becomes possible. Further, heat transfer from the melt mass to the low temperature crucible is small, thermal efficiency is good, and temperature change of the outflowing melt is small.

[Brief description of drawings]

FIG. 1 is a sectional view of an example of a low temperature crucible of the present invention during use.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cooling crucible body 2 ... Ceramic tube 3 ... Lower part melt outlet of a ceramic tube 4 ... Coil 5 ... Power supply line 6 ... Cooling water flow path 7 ... Molten liquid mass 8 ... Solid material for melting 9 ... Outflow liquid

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Yoshino 20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel Corporation Corporate Technology Development Division

Claims (4)

[Claims] 1. A cooling crucible body having an opening for allowing a melt to flow down, a coil arranged on the outer periphery of the cooling crucible body, a shape along the inner wall of the cooling crucible body, and arranged along the inner wall. A low temperature crucible for continuous melt supply, including a ceramic tube having a melt outlet in the lower part. 2. The low temperature crucible according to claim 1, wherein a gap of 1 to 5 mm is provided between the cooling crucible body and the ceramic tube. 3. The low temperature crucible according to claim 1, wherein a low thermal conductivity ceramic coating material is applied to at least one of an inner wall of the cooling crucible body and an outer wall of the ceramic tube. 4. The low temperature crucible according to claim 1, wherein a heat insulating material is placed inside the cooling crucible body and the ceramic tube.