JPS598694A - Apparatus for crystal growth - Google Patents

Abstract

PURPOSE:To prevent the diffusion of air in a crystal growth furnace, and to enable continuous replenishing of the raw material for a long period, by using a raw material feed pipe having double-wall structure, boring a plurality of holes to the wall of the inner tube near the opening end to the crucible, and feeding inert gas through the holes to the furnace. CONSTITUTION:About 3min after the diameter of the crystal 17 has reached the target level, i.e. about 100mm., granular polycrystalline silicon is charged into the crucible at a rate of about 18g/min. At the same time, argon gas having a pressure higher than the atmospheric pressure by about 0.1kg/cm<2> is introduced through the gas inlet 22 and discharged from both ends of the inner tube 201. The granular polycrystalline silicon is scattered by the jet flow of the gas and dropped into the crucible 11. The diffusion of air in the furnace and the choke of the inner tube 201 can be prevented and the continuous replenish of the raw material becomes possible by adjusting the size and the number of the holes 21 bored to the inner tube 201 to proper levels in connection with the diameter of the inner tube 201 of the raw material feed pipe 20.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a crystal growth apparatus, and particularly to a means for supplying raw materials for crystals to be grown into a crucible thereof.

[Technical background of the invention and its problems]

Conventionally, a Czochralski type crystal pulling apparatus as shown in FIG. 1 has been used for crystal growth of V recon and the like.

In this crystal pulling apparatus, for example, after polycrystalline silicon as a raw material is placed in a crucible 11, a heater (heating device) 12 is used.
The polycrystalline silicon is melted to form a silicon melt 16, and a thin seed crystal 1 from a silicon crystal is attached to a pulling shaft 130 provided above the crucible 11 and a seed crystal chuck part 14.
5, lower the pulling shaft 13 and set the seed I&
15 is immersed in the silicon melt 16 in the crucible 11,
Next, by gradually pulling up the pulling shaft 13 while rotating it relative to the crucible 11, a v-recon crystal 17 is grown at the lower end of the seed crystal 15, and a desired ingot is manufactured.

With conventional general equipment, polycrystalline silicon is only put into the crucible at the preparation stage of the pulling process, so it is only possible to melt the raw material equivalent to one pulling process.

This is extremely uneconomical. For this reason, it has been proposed to provide a raw material introduction pipe 19 that penetrates the container 18 and supplies the granular raw material, as shown in FIG. With this device,
When the crystal 17 reaches a predetermined diameter, granular polycrystalline silicon in an amount equal to the crystal growth weight is supplied into the crucible 11 from the outside of the container 1B through the raw material introduction pipe 1g.

However, this method had the following drawbacks.

(2) Since air is diffused into the furnace from the raw material introduction pipe, oxidation of the silicon melt 16 and deterioration of the carbon member occur.

(2) As the raw material introduction pipe acts as a chimney, the gas and oxides in the container 18 are carried out to the outside of the container 18, and at the same time, the oxides adhere to the inner wall of the raw material introduction pipe. If it is used for a long time in this state, the raw material introduction pipe will be blocked by oxides, making it impossible to replenish the granular polycrystalline silicon.

As a method of eliminating such drawbacks, it has been considered to provide a plug or cock for closing the inlet of the raw material inlet pipe (for example, Japanese Patent Application Laid-Open No. 164096/1982). However, due to the force, it is not possible to continuously supply the raw material by blocking the air with a stopper or cock or using methods to prevent oxide adhesion, and the raw material supply must be stopped intermittently every time there is a blockage.

[Purpose of the invention]

In view of the above points, the present invention prevents air from diffusing into the furnace through the raw material inlet pipe, prevents the raw material inlet pipe from being blocked by oxides, etc.
The present invention provides a crystal growth apparatus that enables continuous supply of raw materials.

[Summary of the invention]

In the present invention, 1. The raw material introduction pipe has a double G structure. A circular tube is used to supply the granular raw material, and a plurality of holes are provided in the tube wall near the open end on the crucible side. Then, an inert gas is supplied to the outer tube and released into the inner tube through the plurality of holes.

〔Effect of the invention〕

According to the present invention, by setting the diameter of the inner tube and the diameter and density of the plurality of holes provided in the inner tube to appropriate conditions, diffusion of air into the furnace is prevented, and the inner tube is Continuous crystal growth is possible by continuous supply of raw materials while preventing blockage by oxides and the like.

[Embodiments of the invention]

FIG. 3 is a longitudinal sectional view showing an apparatus according to an embodiment of the present invention.

Portions corresponding to those in FIG. 2 are given the same reference numerals as in FIG. 2, and detailed explanations will be omitted. The basic difference from Fig. 2 is that the inner pipe 20□ and the outer pipe 2 are used as the raw material introduction pipe 20 for replenishing granular raw materials.
0! It uses a double tube structure consisting of. The material of the raw material introduction tube 20 is quartz glass. The inner tube 20 has a raw material inlet 23 opened in the shape of a funnel, and a plurality of holes 21 are provided in the tube wall near the open end on the crucible 11 side. Outer tube 20. Both ends thereof are sealed to both ends of the inner tube 201, and a gas introduction port 22 is provided at the end on the raw material input port 23 side. Outer tube 20. Argon gas, which is the same type as the non-reactive argon introduced into the container 18, is sent from the gas inlet 22 to the crucible 11 side through the hole 21 in the inner tube 201. and raw material input port 2
It is designed to flow into both J.

With such a configuration, after the diameter of the crystal 17 reaches the target value of 100 degrees after starting crystal pulling, 18 gr of multi-grain polycrystalline silicon is injected per minute after 3 minutes have elapsed.

At the same time, argon gas is supplied from the gas inlet 22 at a pressure increased by 1 to 0.1 from the atmospheric pressure, and is discharged to both ends of the inner tube 20□. As a result, the granular polycrystalline silicon falls into the crucible 11 while flying up (by the gas jet).

In this way, K, which enables continuous crystal growth over a long period of time, must not cause oxide adhesion or product deposition in the middle of the circular pipe 201 of the raw material introduction pipe 20.

Experimental data regarding the optimum conditions will be explained below.

Experiments were conducted by varying the diameter and number of holes 21 through which gas is released. The diameter of the hole 21 was from 0.1111 to 1.211 for each crane, and the number of holes was from 3 to 12 for each crane. It has been found that when the gas pressure, the temperature inside the container 18, and the amount of raw material input are the same, the conditions under which the inner tube 20 does not become clogged are very limited.

FIG. 4 shows the results of this experiment, with the diameter of the holes 21 plotted on the vertical axis and the distribution density of the holes plotted on the horizontal axis. The circle mark indicates a point where the inner tube 201 is not blocked even if continuous supply is performed, and the X mark indicates a point where the inner tube 201 is blocked and raw material supply becomes impossible. As is clear from the figure, the ○ marks are almost on a straight line,
By setting the diameter and density of the holes 21 on or near this straight line, continuous raw material supply is possible. Hikoo,
Inner tube 20. It was confirmed that when the diameter of the straight line is increased, the straight line shown by the broken line in FIG. 4 moves upward in parallel.

Thus, according to this embodiment, the inner pipe 20 of the raw material introduction pipe 20
．． Inner tube 20. By setting the diameter and density of the holes 21 to appropriate values, it is possible to prevent air from diffusing into the furnace and from clogging the inner tube 20°, making it possible to continuously replenish raw materials.

Note that as the material for the raw material introduction tube 20, high-purity alumina, sintered silicon nitride, or the like may be used instead of quartz glass.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a conventional general crystal growth apparatus, Fig. 2 is a diagram showing a conventional crystal growth apparatus equipped with a raw material introduction pipe, and Fig. 3 is a diagram showing a crystal growth apparatus according to an embodiment of the present invention. A diagram showing the apparatus and FIG. 4 are diagrams showing experimental data for determining conditions that enable continuous replenishment of raw materials. 1 No... Crucible, 12... Heater, 13... Pulling shaft, 14... Seed crystal chuck part, 15... Seed crystal, 16... Silicon M liquid, 17... Silicon crystal ,
18... Container, 20... Raw material introduction pipe, 20. -8.
Inner pipe, 20,... Outer pipe, 21... Hole, 22... Gas inlet, 23... Raw material input port. Investor's agent Takeshi Suzue Sound Den 1 diagram 2vA 3 419 8 16 O3 diagram

Claims (1)

[Claims] In a crystal growth apparatus equipped with a raw material introduction pipe for supplying granular raw materials from outside the container to a crucible containing a raw material melt, the raw material introduction pipe has a double pipe structure, and an open end on the crucible side of the inner pipe for introducing the granular raw materials. A crystal growth apparatus characterized in that a plurality of holes are provided in a wall of a nearby tube, and an inert gas is supplied to an outer tube and introduced into the inner tube through the plurality of holes.