JPS5914431B2 - Single crystal manufacturing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a manufacturing apparatus for growing a single crystal from a melt, and in particular a single crystal manufacturing apparatus for continuously growing a single crystal while controlling the external shape of the single crystal. It is related to.

Conventional devices of this type use the EFG method (Edge-d
efined, Film-fed Growth
method) and the Stefanoff method are known.

As shown in Fig. 1, the principle of FEG is that the melt 5 in the crucible 2, which has been melted by the heater 1, rises to the upper end of the die 4 due to the capillary action of a thin tube made in the center of the die 4. A single crystal 6 having a shape defined by the outer shape of the upper end of the die 4 is manufactured by pulling up the melt that has wetted the upper end of the die 4.

Its feature is that the wettability of the die 4 allows the melt 5 to be guided to the upper end of the die 4 by utilizing capillary action.

Therefore, although it has the advantage of being able to stably supply a constant amount of melt to the solid-liquid interface, it has the disadvantage that the combinations of melt material and die material are limited.

Furthermore, it has the disadvantage that the single heater 1 must be used to melt the raw material in the crucible 2 and to control the temperature at the upper end of the die 4 in order to grow the single crystal in an optimal state. .

Furthermore, the principle of the Stepanoff method is as shown in FIG. 2, when the melt 5 in the crucible 2 melted by the heater 1 is
By increasing the pressure within the melt 5, it is raised to the upper end of the die 4a through a thin tube made in the center of the die 4a, producing a single crystal 6 having a shape defined by the outer shape of the upper end of the die 4a. It is something.

In this case, in order to increase the pressure within the melt, the melt surface within the crucible 2 is higher than the die 4a.

Its feature is that the wettability of the die 4a is not a problem and the choice of die material is not limited.

However, there is a drawback that the temperature control of the upper end of the die 4a must be performed by a single heater 1.

The common drawback of both of these, that is, the biggest drawback of using a single heater 1 to control the temperature at the upper end of the die 4, 4a is that because the diameter of the heater 1 is large, there is a The point is that it is not possible to create a temperature gradient.

The upper limit of the growth rate of a single crystal is determined by the temperature gradient and latent heat at the boundary between the melt and the crystal, that is, the solid-liquid interface, and in order to increase the growth rate, it is essential to make the temperature gradient at the solid-liquid interface steep. It is.

However, in the FEG method and the Stefanoff method, it is difficult to create a steep temperature gradient at the solid-liquid interface, and rapid growth cannot be expected.

The present invention eliminates the drawbacks of the prior art described above.
The melting section and the die for growing the single crystal are separated from each other and connected to each other by a U-shaped tube, creating a steep temperature gradient between the die and the solid-liquid interface to define the outer diameter of the single crystal. The present invention provides a single crystal manufacturing apparatus characterized in that it is equipped with a first heater for growing a single crystal, a raw material supply device and a second heater for keeping the amount of melt constant and performing continuous growth.

The present invention will be explained in detail below with reference to the drawings.

FIG. 3 shows an embodiment of the present invention, in which the raw material melting section 2,
The die 4b that defines the outer shape of the single crystal, the melting part 2 and the die 4
It is constituted by a U-shaped tube 8 that connects the

Reference numeral 7 denotes a feed material, which is lowered toward the melt surface at a constant speed Vd so as to keep the melt surface at a predetermined constant position as described below.

Reference numeral 1a denotes a first heater for melting the raw material, and a vertical movement mechanism 10 is provided so that the temperature distribution within the crucible 2 can be changed.

16 is a third heater for keeping the temperature inside the U-shaped tube above the melting point, and 1c is a second heater for controlling the temperature of the die 4b.

5 is a melt, and the melt surface can be set higher or lower than the upper end surface of the die 4b.

6 is a grown single crystal, which is pulled at a speed of Vp.

9 is a cooler for making the temperature gradient at the solid-liquid interface steeper.

Production of a single crystal using the apparatus of the present invention is carried out as follows.

The raw material 7 is lowered to keep the melt level constant, and is melted in the crucible 2 by the heater 1a.

The heater 1a is equipped with a vertical movement mechanism 10, and by moving the heater 1a up and down relative to the melting section 2, the melt surface can be adjusted to an arbitrary height relative to the upper end of the die 4b. If it is low, it will be EFG, and if it is high, it will have the same structure as the Stefanoff method.

The melted liquid 5 passes through a U-shaped tube 8 and is connected to a cooler 9 and a second
It reaches the tip of the die 4b, where an extremely steep temperature gradient is formed by the temperature adjusting means consisting of the heater 1c, and is turned into a single crystal.

In this case, Vd and Vp are mainly adjusted so that the amount of single crystal 6 precipitated and the amount of raw material 7 supplied match.

Note that the vertical movement mechanism 10 operates as a position adjustment mechanism for the melt, but the same purpose can be achieved by using the first heater 1a as a divided structure instead of this mechanism and switching between them. can do.

Further, the feeding form of the raw material 7 is not in the solid form as shown in FIG. 3, but may be in the form of a melt or powder.

The cooler 9 may be one that cools the outer periphery of a heat pipe with a hollow single-crystal passageway using cold air or another medium, or a forced air cooler that directly blows cold air.

As the vertical movement mechanism 10, for example, a combination of gears and a chain can be considered.

Moreover, the shape of the U-shaped tube 8 is not limited to a complete U-shape, but may be any other curved shape, such as a part of a circular arc.

One of the features of the present invention is that the temperature at the solid-liquid interface where crystals grow can be controlled independently of the raw material melting heater by a small-diameter dedicated temperature control heater for the die. This makes it possible to create a steep temperature gradient, allowing crystal growth to occur at a high rate.

Another feature of the present invention is that the die material can be selected by considering only the chemical reactivity without considering the wettability between the die material and the melt.

As explained above, since the single crystal manufacturing apparatus of the present invention separates the melting section and the die, the two are thermally separated and the temperature gradient becomes steep at the solid-liquid interface, allowing for rapid crystal growth. .

Furthermore, by raising or lowering the melt surface, either the EFG method or the Stefanoff method can be used, so the die material can be freely selected.

Therefore, it can be used to produce single crystals of various materials such as halides, chalcogenides, and oxides with controlled external shapes.

Furthermore, by continuously supplying raw materials, single crystals can be grown continuously.

[Brief explanation of drawings]

FIG. 1 is a schematic longitudinal cross-sectional view showing an example of the structure of a single crystal manufacturing apparatus using the conventional EFG method, FIG. 2 is a schematic longitudinal cross-sectional view showing an example of the structure of a single crystal manufacturing apparatus using the conventional Stefanoff method, and FIG. 3 is a schematic vertical cross-sectional view showing an example of the structure of a single crystal manufacturing apparatus using the conventional Stefanoff method. 1 is a schematic vertical cross-sectional view showing a structural example of a single crystal manufacturing apparatus according to the present invention. 1... Heater, 1a... First heater, 1b... Second heater, 1c...
・Third heater, 2... Crucible (melting part), 3
・・・・・・Cover, 4゜4a, 4b・・・・・・
Die, 5... Raw material melt, 6... Growing crystal, 7... Raw material, 8... U-shaped tube, 9...
...Cooler, 10...Vertical movement mechanism.

Claims (1)

[Claims] 1 A melting section that holds a melt of the raw material, a first heater for heating the melting section to form a melt of the raw material in the melting section, and a position of the melt surface in the melting section. a position adjustment mechanism for controlling the position of the heater to adjust the position of the heater; a curved tube having one end connected to the melting section for introducing the melt; a second heater for heating the curved tube; a die connected to the other end of the curved tube to continuously pull up and grow a single crystal from the introduced melt; and a die having a steep temperature at the solid-liquid interface between the introduced melt and the single crystal. A single crystal manufacturing apparatus comprising a third heater that heats the tip of the curved tube to create a gradient, and a temperature control means that includes a cooler that cools the pulled-grown single crystal.