JPH02133388A - Production device of silicon single crystal - Google Patents

Abstract

PURPOSE:To prevent the molten raw material from generating solidification in the contact part of partition member when the inside of the crucible receiving molten silicon raw material is divided with the partition member having small openings and a single crystal is pulled up from the inside by constituting the partition member of foamed silica glass. CONSTITUTION:The partition member 11 consisting of foamed silica glass is provided in the crucible 2 receiving molten silicon raw material 4 so as to enclose the silicon single crystal 5 to be pulled up, and the small openings 13 are provided in the partition member 11 so that the molten silicon raw material 4 is allowed to move quietly. The silicon single crystal 5 is pulled up from the inside of the partition member 11 by Czochralski method. Thus, as the partition member 11 consists of foamed silica glass, the heat radiation from the molten liquid 4 near the partition member 11 is restrained, and the molten liquid 4 is prevented from generating solidification in the contact part of the partition member 11.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an apparatus for producing silicon single crystals using the Czochralski method.

[Prior Art] The Czochralski method for manufacturing silicon single crystals has been practiced for a long time and has become a nearly perfected technology.

As is well known, this technology involves placing a molten silicon raw material in a quartz crucible, touching the molten surface of the seed crystal, and at the same time rotating it and gradually pulling it up. As the contact surface solidifies, crystal growth occurs. This is a cylindrical single crystal silicon crystal.

At this time, depending on the purpose, the silicon single crystal is P type or N type.
In order to make a type of semiconductor, appropriate amounts of dopants such as boron, antimony, and phosphorus are mixed into the molten raw material. However, the way these dopants are incorporated into the single crystal is not constant, and the concentration becomes higher in the lower part. It is well known that the uneven distribution of the dopant reduces the yield of wafers.

A double crucible method has been proposed to solve these problems and to equalize the concentration of added elements in a silicon single crystal (W, F, L, Cverton, J, Appl, Ph
ys,.

29.1241 (1958), K.E.Ben5
on, W, I, In, Ishi, P, Martln.

Semjconduator 5ilicon, 33.
(1981), and W, LInK, E, Ben5on.
, Ann, Rev. Mater, Sci., 17.2
73. (1987)).

FIG. 6 schematically shows the structure of a double crucible used in this method.

In these methods, molten raw materials 4a, 4 are placed in the first crucible 1.
A partition 2L having a movable hole 22 or a second crucible 23 having a hole 22 is provided, and the added element concentration in the molten raw material 4a inside the partition 21 or the second crucible 23 (hereinafter simply referred to as partition 21) is By setting the concentration of the added element in the molten raw material 4b outside the partition 21 to different values, the concentration of the added element in the pulled single crystal 5 is made almost constant.

[Problems to be Solved by the Invention] In the silicon single crystal manufacturing method using the partitions 21 as described above, the temperature of the portion where the molten raw material contacts the partitions 21 tends to drop due to heat radiation from the inside of the partitions 21. This is because the material of the partition 21 is transparent silica glass, so its emissivity is considerably higher than that of the molten raw material.Furthermore, the upper part of the crucible 1 is broken by a water-cooled furnace lid, and due to the radiation from this, the partition 21 is higher than the molten raw material. It is thought that this is because they are overheated a lot. Further, since the crucible 1 has a double structure, convection of the molten raw material is suppressed, and the temperature inside the partition 21 is further inhibited from rising.

In addition, in order to grow a single crystal, it is necessary to raise the liquid temperature of the molten raw material inside the partition 21 (crystal growth area) to just above its melting point, but due to the phenomenon described above, the temperature of the molten raw material inside the partition 21 A problem arises in that coagulation occurs at the contact portion with the liquid surface.

However, the above-mentioned conventional method does not take any measures to prevent the occurrence of such coagulation.

[Object of the Invention] The present invention has been made to solve the above-mentioned problems and achieve the objects. The purpose of this invention is to obtain a silicon single crystal manufacturing apparatus that can prevent the above-mentioned problems.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems and achieve the objects. In an apparatus for manufacturing a silicon single crystal by pulling a silicon single crystal from inside the partition member, the device is partitioned by a partition member having small holes penetrated therein so that the molten silicon raw material can move quietly, and all or part of the partition member is A device for producing silicon single crystals made of silica glass with bubbles inserted into the parts.

A silicon single crystal manufacturing apparatus, wherein a portion of the partition member in contact with the molten silicon raw material is made of bubble-filled silica glass, and the other portion is made of transparent silica glass.

A device for producing a silicon single crystal, wherein the bubble-filled silica glass portion of the partition member is made of bubble-filled silica glass having a bubble content (volume ratio) of 0.0196 or more.

The bubble-containing silica glass portion of the partition member has a bubble content (volume rate) of less than 0.01%, and the bubble content rate (volume rate) is reduced by heat for melting the silicon raw material put into the crucible. ) is increased to 0.01% or more.

[Function] In the present invention, since all or a part of the partition member is made of bubble-filled silica glass, heat radiation from the part where the partition member and the silicon molten raw material are in contact is reduced, and the molten raw material from the vicinity of the partition member is prevented from solidifying. prevent.

Embodiments of the Invention First, the fundamental structure of the partition member, which constitutes the main part of the present invention, will be explained. FIG. 5 is a schematic diagram showing a state in which transparent silica glass 21a and bubbled silica glass Lla are immersed in a molten silicon raw material. (a) In the case of the transparent silica glass 21a shown in the figure, since the portion where the molten raw material 4 contacts the glass is transparent, it can be seen that the heat dissipation in the direction above the melt surface is large. Furthermore, since the transparent silica glass 21a absorbs little heat and is difficult to be heated, the temperature of the portion where the molten raw material 4 comes into contact with the glass becomes low, and solidification is likely to occur from this portion.

On the other hand, in the case of bubble-filled silica glass lla, the heat radiation from the part where the molten raw material 4 contacts the glass is scattered by the air bubbles 12 existing in the glass, so that the heat radiation in the direction above the melt surface is reduced. It is smaller than the transparent silica glass 21a. As a result, the temperature of the portion where the molten raw material 4 comes into contact with the glass hardly decreases, and therefore the molten raw material 4 can be prevented from solidifying. Further, as a side effect of the bubble-containing silica glass 11a, since less heat is radiated, temperature fluctuations and wettability fluctuations at the portion where the molten raw material 4 contacts the glass are reduced.

Figure 1 is a sectional view schematically showing an embodiment of the present invention, Figure 2 is a sectional view schematically showing an embodiment of the present invention.
The figure is a sectional view taken along line I-1. In the figure, a quartz crucible 1 is set in a graphite crucible 2, and the graphite crucible 2 is supported on a pedestal 3 so as to be movable up and down and rotatable. 4 is a silicon molten raw material placed in a crucible 1, and a silicon single crystal 5 is grown into a columnar shape.
is raised. 6 is a heater surrounding the graphite crucible 2; 7 is a hot zone insulation material surrounding this heater 6;
These are basically the same as a single crystal pulling apparatus using the normal Czochralski method.

11 is made of high-purity silica glass with bubbles, and crucible 1
As shown in an example in FIG. 3, at least one small hole I3 is formed in a region below the substantially central part in the height direction. This partition member 11 is set in the crucible 1 together with the raw material when it is charged, and after the raw material is melted, it is immersed in the molten raw material 4 so as to surround the single crystal 5, and the upper edge is kept away from the melt surface. It's barely exposed. Further, the lower edge is almost fused to the crucible 1 and does not float up. Therefore, since the molten raw material 4 on the outside of the partition member II can quietly move inward only through the small holes 13, the outside and inside of the partition member 11 (single crystal pulling part) are separated. I can separate it enough. Note that the partition member 11 may be fused to the crucible 1 in advance.

Reference numeral 14 denotes a heat insulating cover, and as mentioned above, the partition member II itself made of silica glass with air bubbles has a function of preventing solidification, but in this embodiment, a heat insulating cover is used to further enhance the heat insulating effect of the molten part of the partition member 11 and its outside. This is what was placed.

In the present invention, by constructing the partition member 11 with aerated silica glass, heat radiation from the portion where the partition member 11 and the silicon molten raw material 4 are in contact is reduced, and solidification of the molten raw material from the partition member 11 is prevented. Can be done.

The effect of preventing the solidification of the molten raw material 4 by this aerated silica glass usually occurs when the air bubble content (volume ratio) is 0.01% or more; In some cases, new bubbles are generated due to the heat used to melt the silicon raw material, or the bubble content (volume rate) is reduced to 0.01 due to the expansion of existing bubbles.
% or more, the same effect of preventing solidification of the melt can be obtained.

The molten liquid solidification prevention effect of the above-mentioned partition part (oit) using the aerated silica glass can be achieved by simply positioning the aerated silica glass in the area where the molten raw material 4 contacts the partition member 11. For example, as shown in FIG. ), the area from the bottom to about 1c+n above the melt surface is made of bubble-filled silica glass, and as shown in Figure (b), only about 1 cI11 above and below the melt surface is made of bubble-filled silica glass. The part made of transparent silica glass also has an anti-coagulation effect.

[Effects of the Invention] As is clear from the above description, the present invention provides a crucible containing a molten silicon raw material with small holes surrounding the silicon single crystal to be pulled and allowing the molten silicon raw material to move quietly. In an apparatus for manufacturing silicon single crystals by partitioning with a partition member having a hole through the partition member and pulling the silicon single crystal from inside the partition member, all or part of the partition member is made of silica glass with bubbles inserted, and the molten liquid near the partition member is By suppressing the heat dissipation, the molten raw material is prevented from solidifying from the part where it contacts the partition member, so that a healthy silicon single crystal can be pulled up. Therefore, the implementation has great effects, such as improving yield and productivity by making the quality uniform in the pulling direction.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional view schematically showing an embodiment of the present invention, Fig. 2
The figure is an I-1 sectional view, FIG. 3 is a side view of an embodiment of the partition member, FIG. 4 is a schematic diagram showing another embodiment of the partition member, and FIGS. 5(a) and (b) are transparent. Figure 6(a) is a diagram comparing the effects of silica glass and bubble-filled silica glass.
, (b) is a schematic diagram showing an example of a conventional double crucible. 1: Crucible, 2: Graphite crucible, 4: Molten raw material, 5: Silicon single crystal, 6: Heater, 8: Chamber, 11: Partition member, 12: Air bubble, 13: Small hole, 14 Two heat insulation covers

Claims (4)

[Claims] (1) The inside of the crucible containing the molten silicon raw material is partitioned by a partition member that surrounds the silicon single crystal to be pulled and has a small hole penetrated so that the molten silicon raw material can move quietly, and the inside of the partition member An apparatus for producing a silicon single crystal by pulling the silicon single crystal from a silicon single crystal, characterized in that all or part of the partition member is made of bubble-filled silica glass. (2) The silicon single crystal manufacturing apparatus according to claim 1, wherein a portion of the partition member that comes into contact with the molten silicon raw material is made of bubble-filled silica glass, and the other portion is made of transparent silica glass. (3) The silicon single crystal according to claim 1 or 2, wherein the aerated silica glass portion of the partition member is composed of aerated silica glass having a bubble content (volume ratio) of 0.01% or more. manufacturing equipment. (4) The cell-filled silica glass portion of the partition member has a cell content (volume percentage) of less than 0.01%,
The silicone according to claim 1 or 2, characterized in that the silicone is made of aerated silica glass whose bubble content (volume ratio) increases to 0.01% or more by heat for melting the silicon raw material put into the crucible. Single crystal production equipment.