JP2000105083A - Melting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a system for melting a material thrown into a crucible by heating through a heating means in which molten liquid can be dropped while securing the melting system at a specified position by making a molten outlet at the lower part of the crucible and providing a movable cover member made of a water-cooled metal plate at the molten outlet. SOLUTION: A crucible 1 comprises an inner quartz crucible 1a and an outer graphite crucible 1b wherein a molten outlet 1c is made at the lower part of the quartz crucible 1a while being directed downward and supported by graphite. A heating means 2 is provided at the outer circumferential part of the crucible 1 and a cover member 4 made of a water-cooled metal plate is provided at the molten outlet 1c. The cover member 4 has double tube structure of inner and outer tubes 5, 6 provided with a metal plate at one end thereof. At the time of melting, the molten outlet 1c is coupled with the cover member 4 and cooled in order to block melting of silicon raw material at the molten outlet 1c and the vicinity thereof. Upon finishing the melting, the cover member 4 is moved obliquely downward and molten is delivered from the molten outlet 1c.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a melting apparatus, and more particularly to a melting apparatus used for a casting apparatus for casting a semiconductor material such as silicon.

[0002]

2. Description of the Related Art Conventionally, there has been a casting apparatus for casting a semiconductor material such as silicon as shown in FIG. In FIG. 4, reference numeral 21 denotes a casting chamber; 22, a melting device for heating and melting a semiconductor material (not shown) such as silicon; and 23, a solidification crucible for solidifying the melted semiconductor material. It is a coagulation device.

The interior of the casting chamber 21 is maintained at a vacuum so that impurities do not enter the semiconductor material. A melting device 22 and a solidifying device 23 are provided in the casting chamber 21.
In addition, a tilting mechanism (not shown) for tilting the melting device 22 to a predetermined angle to enable tapping is provided, and a heater 24 for controlling the solidification state of the coagulation device 23 from below the melting device 22 is provided. A transport mechanism 25 for transporting to the provided position is provided.
1 is designed to be able to move up and down and horizontally.

[0004] In this casting apparatus, the silicon raw material charged into the melting apparatus 22 is heated and melted in the melting apparatus 22 while maintaining the vacuum in the casting chamber 21, and then the melting is performed in the melting apparatus 2.
2 was tilted at a predetermined angle, poured into the coagulation device 23, and conveyed to the coagulation position where the slow cooling heater 24 was provided for coagulation.

[0005]

However, in this conventional casting apparatus, since the melting device 22 is tilted at a predetermined angle and poured into the solidification device 23, a mechanism for tilting the melting device 22 is required, and , A space is needed near the melting device 22 for the melting device 22 to tilt,
There is a problem that the entire casting apparatus becomes complicated and large.

Further, in this conventional casting apparatus, the melting apparatus 22 is tilted at a predetermined angle and poured into the solidification apparatus 23. However, when pouring in a state where a large amount of melt exists in the melting apparatus 22, When pouring in a state in which almost no melt is present in the melting device 22, since the drop position of the melt is different, according to the amount of the melt in the melting device 22 and the tilt angle of the melting device 22, Pouring must be performed while the melting device 22 is moved horizontally, and a space for horizontal movement with the horizontal movement mechanism of the melting device 22 is required, and there is a problem that the casting device becomes complicated and large.

Furthermore, in the case of the system in which the melting device 22 is tilted to supply hot water, the silicon raw material is melted by an induction heating type heating means. The reason is that the induction heating type heating means is easier to tilt the melting device 22 than the resistance heating type heating means. Attempting to tilt the resistance heating type melting apparatus becomes very complicated and impractical. Therefore, in the prior art, the heating means of the melting device 22 is necessarily of the induction heating type. Also, the induction heating type melting power source is very expensive compared to the resistance heating type melting power source. For this reason, conventionally, there was also a disadvantage that the melting power source became very expensive.

[0008] The present invention has been made in view of such problems of the conventional apparatus, and solves the problems of the conventional apparatus that the casting apparatus becomes complicated and large due to the structure and mechanism of the melting apparatus. It is an object of the present invention to provide a dissolving device that has been eliminated.

[0009]

According to a first aspect of the present invention, there is provided a melting apparatus in which a raw material charged into a crucible is heated and melted by heating means. And a lid member made of a movable water-cooled metal plate was provided at the tap hole.

In the above melting apparatus, it is desirable that the heating means is constituted by a resistance heating type heating means.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing one embodiment of a melting apparatus according to the present invention, wherein 1 (1a, 1b) is a crucible, 2 is a heating means, 3 (3a, 3b) is a heat insulating wall, and 4 is a bottom of the crucible. It is a lid member provided in.

The crucible 1 is for heating and melting a semiconductor material such as silicon and pouring a melt into a solidification crucible (not shown). The quartz crucible 1a provided inside and the graphite crucible provided outside. It consists of a crucible 1b. The silicon material melted in the quartz crucible 1a and poured into a solidification crucible (not shown) and solidified is used, for example, as a silicon substrate material for solar cells. Quartz crucible 1a
It dissolves a semiconductor material such as silicon that has been introduced, and is made of quartz or the like in consideration of fire resistance and the fact that impurities do not diffuse into the semiconductor material. Since the quartz crucible 1a is softened at a high temperature and cannot keep its shape, the quartz crucible 1b is held by the graphite crucible 1b.
The size of the crucible 1 is determined by the amount of the semiconductor material to be dissolved and the like.

A tap hole 1c is provided in the lower part of the quartz crucible 1a. The shape of the tap hole 1c is shown in FIGS.
As shown in FIG. 7, it is preferable that the bottom opening 1c is formed downward and is supported by graphite. FIG.
As shown in FIG. 3 (a), it is easier to fabricate the crucible by leaving only the hole while keeping the shape of the crucible bottom. However, in such a shape, after the tapping, the quartz crucible 1a is drawn out as shown in FIG. The gate 1c is deformed, and it is difficult to repeatedly use the quartz crucible 1a. As shown in FIG. 1 and FIG. 2, the quartz crucible 1
The deformation of a is suppressed, and the quartz crucible 1a can be used repeatedly.

As shown in FIG. 1, a heating means 2 is provided on the outer periphery of the crucible 1 (1a, 1b). The heating means 2 includes a resistance heating type heater, an induction heating type coil and the like. The heating means 2 is desirably a heating means of a resistance heating type since the equipment cost of the resistance heating type is lower than that of the induction heating type.

A cover member 4 made of a water-cooled metal plate is provided at the tap hole 1c of the quartz crucible 1a. The lid member 4 has a structure in which a metal plate 4 is provided at one end of a double pipe of an inner pipe 5 provided with a cooling water inlet 5a and an outer pipe 6 provided with a cooling water outlet 6a. ing. This water-cooled metal plate 4
Copper is suitable as a material for the above. The lid member 4 is configured to be able to move together with the double pipe diagonally downward from the tap hole 1c.

As shown in FIG. 2, after the melting of the semiconductor material is completed, the water-cooled metal plate 4 is moved obliquely downward, and the crucible 1 is moved.
The hot water is supplied from the hot water outlet 1c at the bottom of a. The water-cooled metal plate 4 may be moved by any method, but when removing the water-cooled metal plate 4 from the tap hole 1c, it is better to lower the water-cooled metal plate 4 once and then pull it apart. If the water-cooled metal plate 4 is slid sideways and separated from the tap hole 1c, there is a high possibility that the tap hole 1c will be damaged. As shown in FIGS. 1 and 2, the water-cooled metal plate 4 is lowered and then separated from the bearing, which supports the rotational movement of the water-cooled metal plate 4 so that the water-cooled metal plate 4 moves up and down. A very simple structure can be achieved by adopting a bearing that supports sliding movement.

During the melting, the tap hole 1c is cooled by the water-cooled metal plate 4, so that the tap hole 1c and the silicon material in the vicinity thereof do not dissolve. Further, since the melt flowing into the gap of the tap hole 1c is solidified, the melt does not leak from the tap hole 1c. When all of the silicon raw material except for the tap hole 1c and its vicinity is dissolved, the water-cooled metal plate 4 is moved obliquely downward. When the water-cooled metal plate 4 is exhausted, the silicon raw material that has closed the tap hole 1c is melted and discharged.

By adopting the above method, the melting apparatus 1
The tapping water can be supplied to a fixed position without tilting or moving horizontally, and the structure of the melting apparatus 1 becomes extremely simple. Further, a space for rotating the melting device 1 is not required, and the size of the vacuum vessel 7 can be significantly reduced. Further, the heating method can be a resistance heating method.

Around the crucible 1 and the heating means 2, heat insulating walls 3a, 3a made of graphite or the like are used for heat insulation and heat insulation.
b is provided. The heat insulating wall 3b at the top of the crucible 1 is formed to open and close in order to supply the raw material into the crucible 1.

Next, a method for controlling the flow of molten metal will be described.
Set melting crucible 1 and tap 1c of melting crucible 1
Is covered with a water-cooled metal plate 4. A silicon raw material is put into the melting crucible 1. Close the vacuum container 7 and
Exhaust the inside. Heating by the heater 2 dissolves the silicon raw material. A mold (not shown) is set under the tap hole 1c. When all of the silicon except for the tap hole 1c and its vicinity is dissolved, the water-cooled metal plate 4 is removed. Outlet 1c
Is melted and the hot water is poured into the mold. The silicon melt is solidified in the mold. Remove the mold. (3) To continue melting, the tap 1c of the melting crucible 1 is covered with a water-cooled metal plate 4. Then repeat ~ ■.

[0021]

As described above, according to the melting apparatus of the present invention, a tap hole is provided at the bottom of the crucible, and a lid member made of a movable water-cooled metal plate is provided at the tap port.
The melt can be dropped to a predetermined position while being fixed at a predetermined position without tilting or moving the melting device, thereby greatly simplifying the support mechanism of the melting device and miniaturizing the casting device. it can.

In addition, it is possible to use a resistance heating method in which equipment can be poured into a certain position without using a special operation and that the equipment is inexpensive, and the water-cooled copper plate is lowered and then separated. The structure is extremely simple, and the quartz crucible can be used repeatedly.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a melting apparatus according to claim 1;

FIG. 2 is a view showing a state in which a water-cooled metal plate is moved in the melting apparatus according to claim 1;

FIG. 3 is an enlarged view showing a crucible of the melting apparatus according to claim 1, wherein FIG. 3 (a) is a cross-sectional view showing an undesired shape before tapping, and FIG. 3 (b) is an undesired shape after tapping. It is sectional drawing which shows an aspect.

FIG. 4 is a view showing a casting apparatus using a conventional melting apparatus.

[Explanation of symbols]

1 (1a, 1b) ‥‥‥ Crucible, 1c ‥‥‥ Outlet, 2
{Heating means, 3 (3a, 3b)} Insulated wall, 4}
‥‥ Lid member

Claims (2)

[Claims] 1. A melting device for heating and dissolving a raw material charged into a crucible by heating means, wherein a tap hole is provided at the bottom of the crucible, and the tap port portion is formed of a movable water-cooled metal plate. A dissolving apparatus characterized by comprising: 2. The melting apparatus according to claim 1, wherein said heating means comprises a resistance heating type heating means.