JPS5964589A - Method for growing crystal - Google Patents

Abstract

PURPOSE:To make it possible to pull up a single crystal of high quality having a large diameter, by providing a partition wall for preventing convection between the inner side and the crystal growth part of a crucible, and supplying a melt consisting of a crystal component from the bottom or side of the crucible. CONSTITUTION:A melt 13 consisting of a crystal component is supplied from another crucible 22 through a communicating pipe 21 provided on the side of a crucible 11 to the crucible 11. The crucibles 11 and 22 are integrally prepared, and a raw material Si is supplied by dipping a polycrystalline rod 13' in the melt 13 according to the pulling up speed of a crystal 6 to be pulled up. Alternatively, Si powder may be continuously supplied in small portions. The melt 13 may be supplied from the bottom of the crucible 11. Thus, the crystal 16 is pulled up at a constant melt level by automatically supplying the melt 13, and the conventional crucible can be used even in growing a large crystal having 8 inches diameter. Furthermore, the purpose can be fully achieved even by using a shallower crucible.

Description

[Detailed description of the invention] (a) Technical field of the invention The present invention relates to a method for growing crystals.

()]) Technology Background Current semiconductor integrated circuits are made of silicon (Si), gallium arsenide (GaAs) * indium phosphide (InP), etc., which have a certain crystal orientation and are cut from single crystal semiconductors or compound semiconductors. It is formed using a single crystal substrate (wafer).

There are two methods for growing single crystals: the Czochralski method (abbreviated as CZ method) and the floating zone method (abbreviated as F'Z method).
There are two types: the former is characterized by the fact that it is easy to obtain large diameter ones, and the latter is characterized by the fact that it is easy to obtain ones with high purity.

The present invention relates to a method for growing a single crystal using the CZ method.

(c) Prior art and problems The crucibles used to grow single crystals are made of various heat-resistant materials such as platinum (PT), quartz (S102), and boron nitride (BN), depending on the material being melted. Powder made from the same material as the crystal is put in, heated and melted, a seed crystal is brought into contact with the powder, and the powder is gradually pulled up.

Crystal growth is carried out by this.

Semiconductor devices such as semiconductor integrated circuits are all mass-produced, and the diameter of wafers used in batch production is increasingly becoming larger in order to equalize characteristics and reduce costs. .

For example, for 3i, crystal growth technology up to 5 inches in diameter has already been put into practical use, and currently crystal growth up to 8 inches in diameter has been put into practical use.
Efforts are being made to achieve crystal growth.

The crystal growth method will be explained below by taking the growth of a 5ijl' crystal as an example.

Figure 1 is a cross-sectional view showing the pulling mechanism of a resistance heating type C2 furnace. has been done.

The crucible used for crystal growth with a diameter of 4 [inches] or 5 [inches] has a diameter of about 300 [:am:] and a height of more than 2 (l O [dragon]).

Polycrystalline silicon is placed in the crucible 1, and the crucible 1 is heated by flowing metal through a carbon heater 2 provided surrounding the crucible 1, thereby melting the polycrystalline silicon into a melt. Set it to 3.

Here, heating is performed in an argon (Ar) atmosphere, and the temperature is controlled to below ±o, 2 C'C) using a radiation pyrometer.

Now, to grow a single crystal, the tip of the seed crystal 4 having the crystal orientation to be grown is brought into contact with the grape melt 3, but at this time the temperature of the melt 3 is such that the tip of the seed crystal 4 is slightly melted. ＼The temperature is set to maintain equilibrium, and after reaching equilibrium,
The crystal is narrowed at a high pulling rate of 3 to 5 strokes per minute to drive out dislocations in the seed crystal to the outer periphery and suppress the generation of dislocations to eliminate dislocations.

In addition, in order to prevent heat fluctuations at the interface between the melt 3 and the pulled crystal 6 caused by thermal convection and turbulence occurring in the direction of the arrow 5 in FIG. The melt 3 is rotated at low speed to form a lateral forced flow in the melt 3.

Next, the pulling speed is completely lowered and the temperature is gradually lowered to increase the diameter to the desired diameter, and as it cools, a single crystal is grown in the length direction.

When pulling a single crystal with a large diameter using such a growth method, what is required is a small amount of impurities and a large diameter single crystal. This is achieved by obtaining crystals with uniform agricultural distribution and lengths that are approximately the same or longer than conventional ones.

That is, in pulling Si crystallization, it is necessary to maintain an appropriate oxygen content and to produce a crystal with uniform characteristics without growth stripes with different impurity concentration distributions.

However, in the initial stage of crystal pulling, especially at t1'
On the other hand, growth stripes due to mature heat convection are more likely to occur when the temperature is low.

This is 8 [inches] compared to the conventional 5 [inches] E7 crystal growth.
The growth of crystals having a large diameter (inches) cannot be achieved simply by increasing the diameter of the crucible used.

For example, in a crucible used for crystal growth with a diameter of 5 [inches], 1
Silicon (SL) polycrystalline powder of li18 to 20 (k17) is used for filling (JE), and in this case, there is said to be a temperature difference of Fj, 40 to 80 [℃] above and below the melt. If this method is directly applied to crystal growth with a diameter of 8 inches, the influence of thermal convection becomes significant, making it difficult to obtain high quality crystals.

(d) Purpose of the Invention An object of the present invention is to provide a growth method capable of pulling a high-quality single crystal having a large diameter and a length approximately the same as or longer than the conventional method.

(e) Melting of the Invention The purpose of the present invention is to bring a seed crystal into contact with a melt made of crystal components contained in a crucible and grow a crystal on the seed crystal.
This is achieved by providing a partition wall for preventing convection between the inner side surface of the crucible and the crystal growth section, and replenishing the melt into the crucible from the bottom or side surface of the crucible.

(4) Fruit of the invention 11! 2 examples When pulling a single crystal using a growth nail, the crystal is thick f! It is necessary to have a long diameter and a long length, and there is no point in increasing the diameter with a short crystal, both from the standpoint of obtaining a crystal with a uniform oxygen content and from the standpoint of 1 kJ Mr. Currently, 81 single crystals with diameters of 4 [inches] and 5 [inches] and lengths of about 1 [n1] are being produced.

The inventors have long proposed providing a corner wall as a method of mitigating the influence of thermal convection or turbulence on the crystal when pulling a pS1 single crystal. .

The second southern circuit is a cross-sectional view of the crucible 11 when crystal growth is performed using the crucible 11 having partition walls 17, and FIG. 2(B) shows the partition walls 1
7 is shown in perspective.

In other words, the partition wall 17 has a surface diameter of about 10 inches for crystal pulling when a single crystal with a diameter of, for example, 8 inches is to be grown in the medium-heated part of the assembled part 18 and the straight body part 19. An opening 20 is provided.

In this case, the necessary content of the partition wall 17 is 1ii7ii.
An aperture 20k ri is provided between the pulled crystal 16 and the No. 4 part 18 with a gap of an optical width so as not to interfere with the observation of the meniscus line during crystal growth.
It is necessary to put 2.

In the case of this embodiment, the partition wall 17 is made of quartz (S'02 + specific gravity 2
, 20)! , 9 becomes si (ratio m, 2.33
) J: J) Because it is light, it always floats on the melt 13.

Therefore, the presence of the partition wall 17 can prevent thermal convection and turbulence flowing along the side wall of the crucible 11 in the direction of the arrow 15.

However, in order to grow a long crystal, the amount of melt 13 is insufficient as long as a normal size crucible, ie, a crucible with a diameter of 300 (mm) and a height of 200 Ctnm, is used.

Therefore, in the present invention, connecting pipes are provided on the side and bottom of the crucible, and the melt is supplied from a separately provided crucible.

FIG. 3 shows this example, and shows a connecting pipe 23.7 (for example, 5 inches in diameter) provided on the side of a 1-ite crucible (through another crucible, for example, 300 cm in diameter, 23.7 in height).
T and liquid 13 are supplied from a crucible 22 of 0.00 mm.

Two crucibles here 11. ．． In this example, the polycrystal 81 rod 1 is pulled up and immersed in the melt 13 at a rate corresponding to the pulling speed of the crystal 16. However, a method of continuously feeding 3i powder in small amounts may also be used.

In this embodiment, the melt is supplied into the crucible 11 from the side surface of the crucible 11, but it may also be supplied from the bottom of the crucible 11.

In this way, by fully automatically supplying the melt 3 and pulling the crystal while keeping the liquid level constant, even when growing a crystal as large as 8 inches in diameter, a conventional crucible can be used, and even shallower crucibles can be used. The purpose of the present invention can be sufficiently achieved using the following.

Further, since the partition wall 17 is used, the occurrence of thermal convection is small, and the effects of thermal convection and turbulence can be eliminated without rotating the crucible. According to this practical example, it is possible to obtain a single crystal with a length of about 1 to 2 m.

(g) Effects of the Invention The present invention makes it possible to provide a partition wall in a crucible in which crystal growth is performed, and to obtain high-quality crystals that are approximately the same length or longer than conventional crucibles.

[Brief explanation of the drawing]

Fig. 1 is an 18'r plane view explaining the pulling growth of a crystal, Fig. 2 is an explanatory view of the use of a partition wall according to the present invention, and the figure is a cross section illustrating crystal growth, and (B) is a perspective view of a partition wall. , FIG. 3 is a cross-sectional view showing crystal growth using a crucible according to the present invention. In the figure], 11. 22 Fi crucible, 2 is a carbon heater, 3.
13 is a melt, 6 and 16 are pulled crystals, 17 is a partition wall, 18
1t4i: 4 parts, 19 is the straight body part, 21 is the connecting pipe.

Claims (1)

[Claims] When a seed crystal is brought into contact with a melt made of crystal components contained in a crucible and a crystal is grown on the seed crystal, a partition wall f: 11 for preventing convection is provided between the inner side surface of the crucible and the crystal growth section. A method for growing crystals, wherein the loading action is to replenish the melt into the crucible from the bottom or side surface of the crucible.