JPH03183684A - Method for pulling single crystal - Google Patents

Abstract

PURPOSE:To easily form a single crystal composed of two or more parts different from each other in diameter by growing a single crystal part having a first diameter from a melt in a crucible by a desired length, varying the pulling speed or the temp. of the melt and continuously pulling a single crystal part having a second diameter. CONSTITUTION:When a single crystal is pulled by the Czochralski method, a single crystal part 7a having a desired first diameter is grown from a melt in a crucible, at least one of the pulling speed and the temp. of the melt is varied until a second diameter is attained and a single crystal part 7b having the second diameter is continuously grown.

Description

Detailed Description of the Invention [Field of Application of Industry-1-] Kitomon aims to improve productivity and yield in the production of single crystals by the Czochralski method (CZ method), and also to increase the variety of products. This invention relates to a method for responding to increased product scale and larger diameters.

[Prior Art] As a method for manufacturing single crystals of silicon, germanium, gallium arsenide, etc., the CZ method, in which the crystal is grown and pulled from a melt in a crucible, is widely used.

By the way, in recent years, due to the increase in demand for semiconductor single crystals as mentioned above and productivity improvements at device manufacturers,
Single crystals produced by pulling are also rapidly increasing in diameter. However, in addition to being industrially difficult to increase the diameter in terms of crystal growth,
There are also difficulties in the manufacturing process for device manufacturers, especially heat treatment processes such as oxidation, and the technological level varies depending on each manufacturer. Furthermore, the single-connection T+ obtained by the C2 method is used in a wide variety of applications, including MOS, bipolar LSI, transistors, and diodes.

From this point of view, the current situation is that silicon single crystals such as those described above are required in various sizes.

When trying to obtain a silicon single crystal by the CZ method, the third
As shown in the figure, a polycrystalline silicon raw material and, if necessary, a predetermined dopant are loaded in a predetermined amount into a quartz crucible 1, and this raw material is melted by heating from a cylindrical heater 2 to form a silicon melt 3. Then, a crystal insert 6 attached to the tip of the pulling wire 4 and fixed by a metal fitting 5 is immersed in this melt 3 and pulled at a predetermined speed to grow a crystal at the tip of the weighing crystal 6. Conventionally, the single crystal pulling operation is performed by reducing the diameter of the crystal growing at the tip to make it dislocation-free, and then gradually reducing the pulling speed or increasing the melt temperature. The diameter of the grown crystal is expanded to a desired diameter by lowering the temperature, and when the desired diameter is reached, the crystal is grown to a predetermined length while maintaining this diameter while controlling the pulling rate or melt temperature as appropriate. Thereafter, the diameter of the grown crystal is reduced by gradually increasing the pulling speed or the temperature of the melt, and finally the grown single crystal 7 is separated from the surface of the melt 3.

In this way, in the past, in the CZ method, only one diameter was produced by a single drawing operation, and it was not possible to cope with the production of small quantities and a wide variety of single crystals as described above. .

In addition, in such conventional single crystal pulling methods, there is a limit to the ability to make a single crystal into a large i. Increasing the diameter of the crystal required changing the pulling device itself, which was also a problem in terms of capital investment.

[Problems to be Solved by Optical Applications] Accordingly, the present invention aims to cope with the production of small quantities and a wide variety of single crystals in a method for growing single crystals. Another object of the present invention is to enable the production of larger-diameter single crystals using the existing bag method.

[Means for Solving the Problems] The single crystal pulling method of the present invention is a single crystal pulling method in which a single crystal is brought into contact with a melt in a crucible and pulled to grow a single crystal. After growing a single crystal portion having a first diameter of 6 to a desired length, the pulling operation is continued by changing at least one of the pulling rate and the melt temperature, and the first diameter is different from the first diameter. It is characterized by continuously growing a single crystal portion having a second diameter.

The present invention also provides the above method for pulling a single crystal, in which the crucible is continuously or intermittently supplied with raw materials during the single-crystal preparation.

[Function] In the single crystal pulling method of the present invention, by changing at least either the pulling speed or the melt temperature during the single crystal pulling operation, the diameter of the crystal to be grown can be expanded or contracted midway. In addition, single crystals having diameters of two or more scales can be obtained in one pulling operation, and single crystals of polycrystalline species can be supplied in small quantities according to the needs of consumers.

In the present invention, the melt in the crucible and the raw material that is continuously or intermittently supplied may be only a polycrystalline raw material, or may be a polycrystalline raw material to which a dopant is added.

[Example] Hereinafter, the method of the present invention will be explained in more detail based on the drawings.

FIG. 1 shows a manufacturing process in which a first diameter portion having a diameter of 8 inches and a second diameter portion having a diameter of 6 inches are continuously pulled out by an embodiment of the single knot 171 J pulling method of the present invention. This is a schematic representation of Wang Cheng.

In the single-crystal growth method of the present invention, the procedure for growing a single-crystal portion having a desired first diameter to a desired length is similar to that in the conventional single-crystal 17i' growth method. That is, first, a polycrystalline silicon raw material and, if necessary, a predetermined dopant such as phosphorus, boron, antimony, or arsenic are loaded into a quartz crucible 1 of a single crystal pulling apparatus, and this raw material is melted by a cylindrical heater 2. Then, silicon melt 3 is obtained. and pulling wire 4
Attach the insert crystal 6 fixed by the metal fitting 5 to the tip of the
The seed crystal 6 is immersed in this melt 3 and pulled up to grow a crystal at the tip of the seed crystal. After making the diameter of the crystal growing at the tip narrow to make it dislocation-free, the first step is to gradually reduce the pulling rate or lower the melt temperature to obtain the desired growing crystal.
The diameter of the crystal is increased to 8 inches in this example, and when the desired diameter is reached, the crystal is grown for a predetermined length while maintaining this diameter while controlling the drawing speed or melt temperature as appropriate. Make it grow.

Therefore, in the single viscous material drawing method of the present invention, the first diameter portion 7a having such a desired first diameter is
After growing the second crystal, the diameter of the grown crystal is changed and a second crystal is grown continuously. The diameter of the grown crystal is changed by a method similar to the operation at the beginning or end of pulling in conventional single crystal pulling methods.

That is, after growing the first diameter portion 7a to a desired length, at least either the pulling rate or the melt temperature is changed until the single crystal body 7 reaches the desired second diameter. In this embodiment, since the diameter is reduced from the first diameter portion 7a with a diameter of 8 inches to the second diameter portion 7b with a diameter of 6 inches, the pulling speed is gradually increased or the melt temperature is increased. Go. In this way, when the single crystal body 7 reaches the desired second diameter of 6 inches, the diameter is maintained and a predetermined length is formed as the second diameter portion 7b while controlling the pulling speed or melt temperature as appropriate. Then, the single crystal 7 is grown.

After that, as in the conventional single crystal burning method,
It is also possible to gradually increase the pulling speed or increase the temperature of the melt to reduce the diameter of the growing crystal, and finally to separate the grown crystal 7 from the surface of the melt 3 to terminate the growth of the crystal. Furthermore, it is also possible to continue manufacturing the single crystal by changing the diameter of the single crystal 7 in the same manner as described above.

In this embodiment, during the pulling operation of the single pot W1, the polycrystalline silicon raw material and the dopant blended in a predetermined ratio as necessary are fed into the quartz crucible 1 from the raw material supply hopper 8. It is replenished continuously or intermittently depending on the amount reduced by precipitation as a single crystal from the melt 3. As a result, the amount of melt 3 in crucible 1 and the dopant concentration in the melt are kept approximately constant, and stable single crystal growth can be performed continuously.

FIG. 2 shows that a first diameter portion 7a with a diameter of 8 inches and a second diameter portion 7b with a diameter of 10 inches are continuous as one single crystal body 7 by another embodiment of the single crystal cutting method of the present invention. This figure schematically shows the manufacturing process in a typical case.

In this embodiment, the single crystal pulling operation is performed after growing the first diameter portion 7a to a desired length when growing the second diameter portion 7b. 8 inches to 1 diameter
In order to expand the diameter to 0 inch, the above first step is performed except that the pulling speed is gradually decreased or the melt temperature is lowered.
This is carried out in substantially the same manner as in the embodiment.

As in this embodiment, when the second diameter portion 7b is obtained by expanding the diameter of the first diameter portion 7a, the diameter of the second diameter portion 7b is larger than the diameter of the pulling chamber 9 as shown in the figure. However, if the lower part of the second diameter portion 7b is reduced in diameter and separated from the surface of the melt 3 while the upper part of the second diameter portion 7b resides in the melting chamber 10, and the pulling operation is completed (the subsequent removal (Although there is a drawback that the melting chamber 10 side must also be opened during this process), it is possible to obtain a single crystal portion with a larger diameter. As described above, according to one embodiment of the method of the present invention, a single crystal with a larger diameter can be prepared even with a pre-heated pulling apparatus.

[Effects of the Invention] As described above, according to the present invention, single crystal pulling is performed in which a raw material is melted in a crucible to form a melt, and a seed crystal is brought into contact with the melt and pulled to grow a single crystal. In the method, after growing a single crystal portion having a desired first diameter to a desired length, the pulling operation is continued by changing at least one of the pulling rate and the melt temperature, and the first
Since the single-crystal portion having a second diameter different from the diameter of This improves the productivity of single viscous products and makes it possible to produce a wide variety of products in small quantities.

[Brief explanation of drawings]

FIG. 1 is a diagram schematically showing the manufacturing process in an embodiment of the lifting method for single-clustered products of the present invention. Figure S2 schematically shows the manufacturing process in another embodiment of the method for pulling single crystals of the present invention, and Figure 3 schematically shows the manufacturing process in the conventional method for pulling single crystals. It is. 1... Quartz crucible, 2... Heater, 3... Melt liquid,
4... Pull wire, 5... Mounting metal fittings, 6...
Scale crystal, 7... single crystal body, 7a... first single crystal body
Diameter portion, 7b...Second diameter portion of monoviscous body, 8...Raw material supply hopper, 9...Drawing chamber 10...Melting chamber patented dancer Nippon Steel Corporation , Agent Patent Attorney 8 ■1 Mikio (and 1 other person) Engraving of the drawings (no changes to the content)

Claims (2)

[Claims] (1) In a single crystal pulling method in which a seed crystal is brought into contact with a melt in a crucible and pulled to grow a single crystal, after growing a single crystal portion having a desired first diameter to a desired length, A single crystal characterized in that the pulling operation is continued by changing at least either the pulling speed or the melt temperature to continuously grow a single crystal portion having a second diameter different from the first diameter. How to pull up. (2) Claim 1, wherein the crucible is continuously or intermittently supplied with raw materials during the single crystal pulling operation.
The method described in.