JP2001220291A - Method for producing silicon wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize the miniaturization of crystal defect grains and the improvement of pulling up speed at the same time, and improving the production efficiency of a wafer for annealing. SOLUTION: This method for producing a silicon wafer in pulling up a silicon single crystal by the CZ method, is provided by installing and adjusting a cooler, performing the application and adjustment of a magnetic field, and adopting >=1 factors selected from a group consisting of the installation and adjustment of a heat-shielding material, the adjustment of a distance between the bottom of the heat-shielding material and a melt level, and the adjustment of nitrogen- doping amount to aim at the improvement of the pulling speed of the silicon single crystal and miniaturization of the crystal defect grains simultaneously.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for optimizing manufacturing conditions of a silicon wafer manufactured by a CZ method (Czochralski method).

[0002]

2. Description of the Related Art In a silicon wafer manufactured by the CZ method for a semiconductor device, only a silicon ingot cut out from a silicon ingot has crystal defects on its surface which degrade device quality. By performing (annealing), void defects on the wafer surface layer disappear. As an example, a CZ silicon wafer subjected to a hydrogen heat treatment (hydrogen annealing treatment)
For example, it is known that void defects in the surface layer of a wafer detected as LSTD, FPD, and COP disappear and exhibit excellent oxide film breakdown voltage characteristics (Japanese Patent Publication No. 3-80338).

[0003] However, there is a problem that the effect of the hydrogen annealing treatment is limited only to the vicinity of the very surface of the wafer. In this regard, the present inventors have found that the annihilation rate or annihilation depth of defects near the surface layer due to high-temperature annealing generally depends on the initial defect size. Improvement (Japanese Patent Application No. 9-27)
213), V / G (V: pulling speed, G: temperature gradient in the crystal axis direction near the melting point) and control of OSF ring diameter (Japanese Patent Application No. 10-260666) to reduce the size of defects in the crystal. By doing so, a method of enlarging a defect-free region from a wafer surface layer to a relatively deep portion has been proposed.

Here, according to this method, it is possible to reduce the crystal defects during growth to a size that can be easily eliminated by annealing treatment when the crystal pulling speed is increased. become. In addition, if the crystal pulling speed is increased, the production amount of silicon ingots per unit time naturally increases, so that the production efficiency of the wafer improves.

[0005]

[Problems to be solved by the invention]

[0006] Then, if it becomes possible to pull up the crystal faster than previously assumed,
Regardless of whether it is for epi or for annealing, it is possible to further improve the wafer production efficiency for all types of wafers.

When the crystal pulling speed is increased,
If it becomes possible to reduce the size of crystal defects at least in a form that is not adversely affected by it, it becomes possible to achieve the reduction of crystal defects even under high-speed pulling conditions, and in particular, the pulling speed and If the reduction (miniaturization) of crystal defects can be improved at the same time, a wafer for annealing (a crystal defect is likely to disappear and a wafer suitable for performing an annealing process) can be rapidly manufactured. become.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and a first object of the present invention is to increase the crystal pulling speed more than previously supposed, so that the annealing wafer can be used. The purpose is to improve the production efficiency of all types of wafers, not limited to epi wafers. Further, a second object of the present invention is to simultaneously realize the reduction of crystal defects and the improvement of the pulling speed, which have been assumed so far, and to improve the production efficiency of the annealing wafer.

[0009]

According to the present invention, in order to achieve the first object, at least a combination of factors that do not act in the negative direction (preferably, a combination of factors that act in the positive direction). By locating and combining them, the crystal pulling speed can be improved more than previously expected, thereby increasing the production efficiency of all types of wafers, not limited to annealing wafers and epi wafers. To improve.

Further, in order to achieve the second object, as in the case of the first object, a combination of factors capable of simultaneously realizing the reduction of crystal defects and the improvement of the pulling speed is determined. By combining them, it is possible to reduce the size of crystal defects and improve the crystal pulling speed more than expected so far, thereby improving the production efficiency of annealing wafers.

Here, the control of the crystal defect size in the process of producing a single crystal by the CZ method is delicate in which very delicate elements are entangled, and the common sense in the absence of a cooler is the same as when a cooler is installed. There is no guarantee that it will work. Under such circumstances, the discovery that the effect of crystal defect refinement by nitrogen doping is maintained even when a cooler is installed has greatly contributed to the completion of the present invention. When this is considered more abstractly, in the present invention, in order to solve the conventional problem of improving the crystal pulling speed, basically, the improvement of the crystal pulling speed and the reduction of the size of crystal defects are considered. Providing a group of factors (factor pallet) consisting of factors that do not include at least factors that interfere with each other or cancel each other out of the factors related to Becomes Then, one or more factors selected from this group of factors (pallet) are selected to obtain an additive effect, more preferably a synergistic effect, with respect to the improvement of the crystal pulling speed and the reduction of the crystal defects. It is.

More specifically, the present invention provides the following.

(1) In pulling a silicon single crystal by the CZ method, adjustment of a hot zone, installation and adjustment of a heat shield, adjustment of the distance between the bottom of the heat shield and the melt surface, installation of a cooler A method of improving the pulling speed of a silicon single crystal pulled by the CZ method by adopting one or more factors selected from the group consisting of adjustment and application and adjustment of a magnetic field.

(2) In pulling a silicon single crystal by the CZ method, adjustment of a hot zone, installation and adjustment of a heat shield, adjustment of the distance between the bottom of the heat shield and the melt surface, installation of a cooler・ Adopting at least one factor selected from the group consisting of adjustment, application and adjustment of a magnetic field, and adjustment of the amount of nitrogen doping, to reduce the crystal defect size of the silicon single crystal pulled by the CZ method. How to aim.

(3) In pulling a silicon single crystal by the CZ method, a cooler is installed and adjusted, a magnetic field is applied and adjusted, a hot zone is adjusted, a heat shield is installed and adjusted, and a heat shield is installed. By adjusting the distance between the bottom and the melt surface, and by adopting one or more factors selected from the group consisting of adjusting the amount of nitrogen doping,
A method for simultaneously improving the pulling speed of a silicon single crystal pulled by the CZ method and reducing the crystal defect size.

(4) A silicon ingot for high-speed mass production of wafers, manufactured by the method according to any one of (1) to (3), wherein the crystal defect size is reduced.

(5) An epi wafer or an annealing wafer cut from the silicon ingot for high-speed mass production of wafers described in (4).

(6) In order to optimize the pulling speed of the silicon single crystal pulled by the CZ method, adjustment of a hot zone, installation and adjustment of a heat shield, and between the bottom of the heat shield and the melt surface A method of adopting one or more factors selected from the group consisting of adjusting the distance of the object, setting and adjusting the cooler, applying and adjusting the magnetic field, and adjusting the nitrogen doping amount.

(7) In pulling a silicon single crystal by the CZ method, adjustment of a hot zone, installation and adjustment of a heat shield, adjustment of the distance between the bottom of the heat shield and the melt surface, installation of a cooler A computer-readable storage medium storing two or more data selected from the group consisting of adjustment and application and adjustment of a magnetic field;

(8) In pulling a silicon single crystal by the CZ method, adjustment of a hot zone, installation and adjustment of a heat shield, adjustment of a distance between the bottom of the heat shield and the melt surface, installation of a cooler A computer-readable storage medium storing two or more data selected from the group consisting of adjustment, application and adjustment of a magnetic field, and adjustment of the amount of nitrogen doping.

(9) When pulling up a silicon single crystal by the CZ method, together with data for setting and adjusting a cooler, application and adjustment of a magnetic field, adjustment of a hot zone,
Computer readable storage storing two or more data selected from the group consisting of setting and adjusting the heat shield, adjusting the distance between the bottom of the heat shield and the melt surface, and adjusting the nitrogen doping amount. Medium.

(10) A program for increasing the pulling speed of a silicon single crystal pulled by the CZ method, comprising adjusting a hot zone, adjusting a heat shield, and adjusting a distance between the bottom of the heat shield and the melt surface. A computer-readable storage medium storing one or more programs selected from the group consisting of distance adjustment, cooler adjustment, and application / adjustment of a magnetic field.

(11) A program for reducing the crystal defect size of a silicon single crystal pulled by the CZ method, comprising adjusting a hot zone, adjusting a heat shield, and adjusting a distance between the bottom of the heat shield and the melt surface. A computer-readable storage medium storing one or more programs selected from the group consisting of adjustment of distance, adjustment of cooler, application and adjustment of magnetic field, and adjustment of nitrogen doping amount.

(12) This is a program for simultaneously improving the pulling speed of a silicon single crystal pulled by the CZ method and reducing the crystal defect size.
A group consisting of adjustment and application of a magnetic field, adjustment of a hot zone, installation and adjustment of a heat shield, adjustment of the distance between the bottom of the heat shield and the melt surface, and adjustment of the nitrogen doping amount, together with the data to be adjusted. A computer-readable storage medium storing one or more selected programs.

(13) A silicon single crystal pulling apparatus for storing a storage medium according to any one of (7) to (9) and / or a storage medium according to any one of claims 10 to 12.

[Definition of Terms] The "heat shield" is provided in the furnace of a CZ single crystal ingot manufacturing apparatus for manufacturing a single crystal ingot by the CZ method. It is installed so as to surround the periphery of the single crystal ingot pulled up from the surface, and functions to control the amount of heat radiated from the melt and the heater. This heat shield not only controls the amount of radiant heat but also regulates the flow of the inert gas passed through the CZ furnace.
It is also called a gas straightening tube. The “hot zone” means a certain area in the CZ furnace where the heating action of the heater is broadly and directly or indirectly affected by the heating action. It may or may not include it. "Hot zone adjustment" includes adding / changing / deleting a member, changing the material / type of a member, changing the arrangement of members, adding / changing / deleting the motion state of a member, and changing the energy state of a hot zone. Changes are included.

Regarding the "distance between the bottom of the heat shield and the melt surface", any distance can be used as long as it can be measured accurately.
It is preferable to use a melt level detecting device disclosed in JP-A-071149. In this regard, since the lower end position of the heat shield actually changes during pulling due to thermal stress, as shown in Japanese Patent Application No. 11-071149,
It is preferable to use a sensor that can appropriately measure the distance between the lower end of the heat shield and the melt surface.

The term “single crystal” as used in this specification is a broad concept including ingots, bulks, and wafers.

In this specification, "adjustment" means
It is a broad concept that includes changes in all states and changes in variables such as adjustment of positional relationships, forms, and strength.

The term "nitrogen doping" means that nitrogen is added during crystal growth by introducing nitrogen gas during crystal growth or adding nitride to the silicon raw material melt. A method that utilizes the fact that the defect size is reduced by "nitrogen doping" and applies it to an annealed wafer has also been proposed (JP-A-10-98047).

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION With respect to a combination of two or more "factors", the following three are effective as measures for reducing crystal defects in a crystal growth stage.

1) To increase the cooling rate of the crystal,
It is necessary to increase the temperature gradient of the crystal and increase the pulling speed, and install a heat shield to block the radiant heat from the melt and heater from the crystal and a cooler to cool the crystal itself. .

2) By adding nitrogen during crystal growth,
A method of reducing the defect size (however, the defect density greatly increases).

3) A method of applying a magnetic field during crystal growth. That is, when a magnetic field is applied during the crystal growth, natural convection in the vertical direction of the silicon melt is suppressed, so that the temperature gradient of the melt increases and the temperature gradient of the crystal increases. as a result,
The pulling speed is increased by about 20% as compared with the case where no magnetic field is applied, which is effective in increasing the cooling speed. Further, as has been conventionally known, the fact that the oxygen concentration can be controlled in a wide range also has an effect on the control of oxygen precipitation that becomes a getter site for heavy metals.

Here, as shown in a later embodiment,
At least, there is no relationship between the installation of the cooler, the application of the magnetic field and the nitrogen doping, such as mutual interference or cancellation, and an additive effect or a synergistic effect can be expected. That is, by setting the conditions at least by any one or combination of the cooler installation, nitrogen addition, and magnetic field application, the crystal defect size can be controlled, and the wafer characteristics after the heat treatment can be optimized.

In this regard, first, regarding the relationship between these factors and the installation and adjustment of the heat shield, and the adjustment of the distance between the bottom of the heat shield and the melt surface, the interference between the installation of the cooler and the nitrogen doping is considered. Or there is no offset factor. In addition, in relation to the magnetic field, small waves on the melt surface disappear when a magnetic field is applied, so that when a magnetic field is applied, the heat shield can be brought closer to the melt surface. By bringing the heat shield closer to the melt surface, the heat shielding effect on the crystal can be improved, and the temperature gradient of the crystal can be increased. Contribute to the improvement of Therefore, installation of heat shield
In the relationship between the adjustment and the magnetic field, it is considered that although it works positively, it does not work negatively. Thus, in principle, the application of a magnetic field can be applied to the pallet together with the installation of a cooler and nitrogen doping as a factor of crystal defect refinement.

In connection with this, V / G control and OSF
The method of reducing the defect size by controlling the ring diameter (Japanese Patent Application No. 260666) and increasing the crystal cooling rate (Japanese Patent Application No. 27213/1997) alone increases the heat capacity due to the increase in the crystal diameter. There is a problem in that it is extremely difficult to achieve a cooling rate that can sufficiently reduce the defect size.Therefore, nitrogen doping alone has a limit on the nitrogen concentration that can be present in a crystal, and the nitrogen concentration cannot be increased. In this case, oxygen precipitation is promoted, and there is a problem that the addition amount of nitrogen is limited because a DZ layer cannot be secured.However, by appropriately combining a cooler, nitrogen doping, and application of a magnetic field, It is possible that it may be possible to find a prospect that the above-mentioned problems of the case where the crystal cooling rate is increased alone and those of the case where nitrogen is doped alone are solved.

[Embodiment in the case of using a cooler] As an embodiment in the case of using a cooler, the following is mentioned.

[0039]

[Table 1]

[Embodiment in case of adding cooler + nitrogen]
Embodiments in the case of “cooler + nitrogen addition” include the following.

[0041]

[Table 2]

[0042]

EXAMPLE In this example, the crystal had a diameter of 200 mm doped with boron as a dopant, a p-type, and a crystal orientation <
100>, the relationship between the defect density and the defect size and the nitrogen concentration when nitrogen was added to the conventional condition and the cooler installation condition in a crystal having a resistivity of 10 Ωcm was examined (FIG. 1).

Further, the relationship between the cooling rate, the defect density and the defect size when nitrogen was added to the conventional condition and the cooler installation condition for the above crystal was examined (FIG. 2).

In this regard, a typical LST in-plane map diagram and an example of defect density are also shown (FIG. 4). In the LST evaluation method, a visible light laser (λ690 nm, MO601 manufactured by Mitsui Mining & Smelting Co., Ltd.) is obliquely incident on the wafer surface, and the scattered light is detected by a CCD to detect crystal defects having a depth of about 5 μm on the wafer surface layer. The detection method was adopted.

First, as shown in FIG. 1, it can be seen that the reduction in the size of crystal defects with an increase in the amount of nitrogen doping is accelerated by the presence of a cooling body (cooler). FIG.
As shown in FIG. 5, it can be seen that the reduction of crystal defects with an increase in the cooling rate is accelerated with an increase in the nitrogen doping amount. From these, it can be seen that at least the effect of crystal defect refinement by nitrogen doping is maintained even after the cooler is installed.

FIG. 3 is a diagram showing the influence of the application of a magnetic field on the crystal growth rate and the defect size. In the figure, the histogram indicates the defect size (vertical axis on the right), and the black square indicates the pulling speed (vertical axis on the left).

As shown in FIG. 3, when a magnetic field is applied, the size of the crystal defects is reduced while the size of the crystal defects is reduced.
At the same time, the pulling speed can be increased.

This indicates that the application of the magnetic field has a positive effect on the pulling speed. That is, as described above, the pulling rate can be increased by applying a magnetic field to calm down the melt surface and bringing the bottom surface of the heat shield closer to the melt surface to increase the temperature gradient in the vertical direction of the crystal. It is thought that it can be improved,
In any case, the pulling speed can be actually increased by applying a magnetic field.

Further, FIG. 4 shows that the heat treatment was performed on the crystal pulled up with the cooler installed, and the heat treatment was performed on the crystal pulled up with the nitrogen dope with the cooler installed. It can be seen that the defect density is lower than that which has been subjected to heat treatment.
It can be seen that the defect density after annealing is significantly reduced by improving the heat shield, using a cooler, or combining a cooler and nitrogen doping. Note that the heat treatment atmosphere at the time of annealing may be performed in a non-oxidizing Ar atmosphere or He atmosphere, or a mixed gas of these and hydrogen.

[Pulling device provided with predetermined program]
In the silicon single crystal pulling apparatus according to the present invention, a storage medium having data as shown in the following table is stored, and a silicon single crystal pulling operation is performed based on the storage medium. In the table,
"Cooler installation / adjustment", "Hot zone adjustment",
The data on each factor of "Installation / adjustment of heat shield", "adjustment of distance between bottom of heat shield and melt surface", and "application / adjustment of magnetic field" are related to higher crystal pulling speed. The data are SD1, SD2, SD3,
It is defined as SD4 and SD5. And, at the same time, as data on the grain refinement of defects in the crystal,
The data are defined as KD1, KD2, KD3, KD4 and KD5, respectively, and as data simultaneously related to the increase in the crystal pulling speed and the reduction in the size of defects in the crystal, SK-
It is defined as D1, SK-D2, SK-D3, SK-D4 and SK-D5.

The "adjustment of the amount of nitrogen doping" is not related to the increase in the crystal pulling speed, and therefore "S
-D "and" SK-D ", and are simply defined as K-D6 as data relating only to the reduction of the size of defects in the crystal.These data are basically past data And the form may be appropriately updated as needed, regardless of whether it is a calculated value or an actually measured value.

[0052]

[Table 3]

Next, the correspondence between each data and the program for controlling each of the above factors using the data is as shown in the table below. The storage medium having the data shown in Table 3 and the storage medium having the program shown in Table 4 may both be built in the apparatus, stored externally, and taken out when necessary. You may.

[0054]

[Table 4]

In the operation of the pulling device according to the present invention, first, after initial data is taken, an appropriate factor is selected from the data palette of Table 3. Here, the data that is initially captured is
These include the crucible size, the initial material input amount, the crystal diameter and crystal length of the crystal to be obtained, the number of rotations of the crystal and the crucible, and the like.

When an appropriate factor is selected from the data palette shown in Table 3, a program corresponding to the selected data is started, and the internal environment (such as the form of a hot zone) of the pulling apparatus according to the present invention is adjusted. . And then,
The pulling speed of the single crystal is set at the highest possible speed in the prepared internal environment, and the silicon single crystal is pulled while performing fine adjustment during the pulling.

By operating the apparatus in this manner, a silicon ingot and a silicon wafer can be manufactured at a speed higher than previously expected, and the silicon obtained in this manner can be manufactured. Many ingots and silicon wafers have a small defect size, and such a wafer is suitable as an annealing wafer.

[0058]

According to the method of the present invention as described above, in order to optimize the complete area of the wafer surface layer which is important for the device characteristics by the high-temperature heat treatment, it is necessary to generate the crystal at the crystal growth stage.
A great effect can be obtained by extracting measures for reducing the size of growing defects and measures for realizing high-speed crystal pulling, and combining them.

As described above, the integrity of the wafer surface layer can also be expected by increasing the heat treatment temperature or prolonging the heat treatment time. appear. On the other hand, the present invention can be said to be a method having a great effect in absorbing such disadvantages of the heat treatment conditions.

Furthermore, the device structure can be roughly classified into a stack system and a trench system, and the depth of the complete region of the wafer surface layer required by the device changes depending on the structure. It can be said that the present invention is also an effective method for achieving optimization.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between a defect density and a defect size and a nitrogen concentration when nitrogen is added to a conventional condition and a cooler installation condition.

FIG. 2 is a graph showing a relationship between a cooling rate, a defect density, and a defect size when nitrogen is added to a conventional condition and a cooler installation condition.

FIG. 3 is a diagram showing the effect of a magnetic field application on the crystal growth rate and defect size.

FIG. 4 is a diagram showing a typical LST in-plane map and an example of defect density.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Hiroshi Inagaki 2612 Shinomiya, Hiratsuka-shi, Kanagawa F-term in Komatsu Electronic Metals Co., Ltd. 4G077 AA02 BA04 CF10 EB01 EC10 EG18 EG19 EG25 EH09 EJ02 PF17 PF51 RA03

Claims (13)

[Claims] 1. When pulling a silicon single crystal by the CZ method, adjustment of a hot zone, installation and adjustment of a heat shield, adjustment of the distance between the bottom of the heat shield and the melt surface, installation of a cooler, A method for improving the pulling speed of a silicon single crystal pulled by the CZ method by adopting one or more factors selected from the group consisting of adjustment and application and adjustment of a magnetic field. 2. When pulling a silicon single crystal by the CZ method, adjustment of a hot zone, installation and adjustment of a heat shield, adjustment of the distance between the bottom of the heat shield and the melt surface, installation of a cooler, By adopting at least one factor selected from the group consisting of adjustment, application and adjustment of a magnetic field, and adjustment of the amount of nitrogen doping, the crystal defect size of the silicon single crystal pulled by the CZ method is reduced. Method. 3. When pulling a silicon single crystal by the CZ method, a cooler is installed and adjusted.
Application and adjustment of magnetic field, adjustment of hot zone, installation and adjustment of heat shield, adjustment of distance between bottom of heat shield and melt surface,
And adopting at least one factor selected from the group consisting of adjusting the amount of nitrogen doping and simultaneously improving the pulling speed of the silicon single crystal pulled by the CZ method and reducing the crystal defect size. Method. 4. A silicon ingot for high-speed mass production of wafers, manufactured by the method according to claim 1, wherein the crystal defect size is reduced. 5. An epi wafer or an annealing wafer cut from the silicon ingot for high-speed mass production of a wafer according to claim 4. 6. A method for adjusting a pulling speed of a silicon single crystal pulled by a CZ method, adjusting a hot zone, setting and adjusting a heat shield, and adjusting a distance between a bottom of the heat shield and a melt surface. Adjustment of distance, installation and adjustment of cooler, application of magnetic field
A method of adopting at least one factor selected from the group consisting of adjustment and adjustment of the nitrogen doping amount. 7. When pulling a silicon single crystal by the CZ method, adjustment of a hot zone, installation and adjustment of a heat shield, adjustment of a distance between the bottom of the heat shield and the melt surface, installation of a cooler, and the like. A computer-readable storage medium storing two or more data selected from the group consisting of adjustment and application and adjustment of a magnetic field. 8. When pulling a silicon single crystal by the CZ method, adjustment of a hot zone, installation and adjustment of a heat shield, adjustment of the distance between the bottom of the heat shield and the melt surface, installation of a cooler, A computer-readable storage medium storing two or more data selected from the group consisting of adjustment, application and adjustment of a magnetic field, and adjustment of a nitrogen doping amount. 9. In pulling a silicon single crystal by the CZ method, together with data for setting / adjusting a cooler, applying / adjusting a magnetic field, adjusting a hot zone, setting / adjusting a heat shield, and adjusting a heat shield. A computer-readable storage medium storing two or more data selected from the group consisting of adjusting the distance between the bottom and the melt surface and adjusting the nitrogen doping amount. 10. A program for increasing a pulling speed of a silicon single crystal pulled by a CZ method,
Contains one or more programs selected from the group consisting of adjusting the hot zone, adjusting the heat shield, adjusting the distance between the bottom of the heat shield and the melt surface, adjusting the cooler, and applying and adjusting the magnetic field. Computer readable storage medium. 11. A program for reducing the size of crystal defects in a silicon single crystal pulled by a CZ method, comprising: adjusting a hot zone, adjusting a heat shield, and adjusting a distance between the bottom of the heat shield and the melt surface. A computer-readable storage medium storing one or more programs selected from the group consisting of adjustment of a distance, adjustment of a cooler, application and adjustment of a magnetic field, and adjustment of a nitrogen doping amount. 12. A program for simultaneously improving the pulling speed of a silicon single crystal pulled by the CZ method and reducing the size of crystal defects, and applying and adjusting a magnetic field together with data for setting and adjusting a cooler. One or more programs selected from the group consisting of adjusting a hot zone, setting and adjusting a heat shield, adjusting the distance between the bottom of the heat shield and the melt surface, and adjusting the nitrogen doping amount are stored. Computer readable storage medium. 13. The storage medium according to claim 7, wherein:
13. A silicon single crystal pulling apparatus for storing a storage medium according to claim 10.