JPH0129241Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Industrial Application Field] The present invention relates to a single crystal manufacturing apparatus using the Czyochralski method. [Prior art] To grow a single crystal using the Czyochralski method, after heating a crucible and melting the raw materials in the crucible,
This is done by dipping a seed crystal into a melt and pulling it up. In this method, in order to grow a high-quality single crystal, it is necessary to provide an appropriate gradient in the temperature distribution in the vertical direction of the solid-liquid interface. For this reason, the crucible is surrounded by refractories and methods of heating the crucible are studied to create an appropriate temperature gradient. However, as single crystal growth progresses,
As the amount of raw material melt in the crucible decreases,
The solid-liquid interface is lower than it was at the beginning of crystal growth, and the crucible wall directly above the solid-liquid interface is heated, which causes an afterheater effect, resulting in a large change in temperature gradient, which causes a decline in crystal quality. Conventionally, in order to prevent changes in the vertical temperature gradient as described above, the method used was to move the high-frequency heating coil, which is the heating source of the crucible, up and down, but this method faithfully reproduces the temperature gradient during the initial stage of crystal growth. It was difficult to achieve this, and deterioration in quality, especially in the lower part of the crystal, was unavoidable. [Purpose of the invention] An object of the invention is to provide a single crystal manufacturing apparatus that eliminates the above-mentioned drawbacks and can maintain the temperature gradient at the early stage of crystal growth even in the latter stage of crystal growth. [Structure of the invention] According to the invention, in a single crystal production apparatus that includes a crucible and uses the Czyokralski method, at least three A single crystal manufacturing apparatus is obtained, which is characterized by having a main gas pipe and an adjustment mechanism for adjusting the discharge amount of the gas. [Examples of the invention] The invention will be described below based on examples. First, the structure of the single crystal manufacturing apparatus according to the present invention will be explained with reference to FIGS. A high-frequency coil 3 is arranged at. Immediately above the wall of the crucible 2 and slightly inside the wall, three gas pipes 4 are arranged radially at equal intervals as shown in the figure, and the ejection ports of the gas pipes 4 are directed downward. (The material of the gas pipe varies depending on the type of crystal being grown.) This gas pipe 4 is connected to a flow meter 6 as shown in the figure via a gas amount adjusting section 5, and is further connected to a gas cylinder 7. A raw material such as Si is placed in a crucible 2, and the crucible 2 is heated by a high frequency coil 3 to melt the raw material.
A seed crystal (not shown) is immersed in this melt 8, and the seed crystal is pulled up to grow a single crystal.
At this time, a gas such as N ₂ is sent from the gas cylinder 7, and the amount of this gas is adjusted by the gas amount adjusting section 5 so that the gas flows equally through the three gas pipes 4. Further, the gas flow rate is measured by a flow meter. Next, with reference to FIGS. 2a and 2b and FIGS. 3a, b, and c, the inventor will explain the results of manufacturing a single crystal using the single crystal manufacturing apparatus having the above-described structure. In manufacturing this single crystal, the inner diameter is 50 mm, the depth is
A 50 mm crucible is used, and the raw material melt is charged into the crucible to a position 5 mm from the top of the crucible.
Also, the atmospheric gas flowed through the gas pipe at this time was
The table _below shows the relationship between the position of the raw material melt, that is, the position of the solid-liquid interface, and the gas flow rate indicated by the flow meter.

[Effect of idea]

As explained above, by using the single crystal apparatus according to the present invention, a constant vertical temperature distribution can be obtained from the early stage to the late stage of crystal growth, and the advantage is that it is possible to produce high-quality single crystals. be.

[Brief explanation of drawings]

Figure 1a is a plan view showing the main parts of the single crystal manufacturing apparatus according to the present invention, Figure 1b is a side sectional view showing the main parts of the single crystal manufacturing apparatus according to the invention, and Figure 2a is the initial stage of crystal growth. FIG. 2b is a diagram showing the positional relationship between the crucible and the solid-liquid interface in each step, and FIG. 2b shows the vertical direction in the state shown in FIG. Figure 3a is a diagram showing the temperature distribution, Figure 3a is a diagram showing the positional relationship between the crucible and the solid-liquid interface in the later stages of crystal growth, and Figure 3b is a diagram showing the positional relationship between the crucible and the solid-liquid interface in the latter stages of crystal growth. FIG. 3c is a diagram showing the temperature distribution in the vertical direction in the state shown in FIG. 3a in the case of manufacturing a single crystal, and FIG. a
FIG. 3 is a diagram showing the vertical temperature distribution in the state shown in FIG. 1... Fireproof support case, 2... Crucible, 3
...High frequency coil, 4...Gas pipe, 5...Gas amount adjustment section, 6...Flowmeter, 7...Gas cylinder, 8...
... Raw material melt, 9... Single crystal.

Claims (1)

[Scope of utility model registration request] A single crystal manufacturing apparatus comprising a crucible and using the Czyochralski method, at least three gas pipes arranged radially directly above the wall of the crucible for discharging gas into the crucible, and a discharge amount of the gas. A single crystal manufacturing apparatus characterized by having an adjustment mechanism for adjusting.