JP2001002491A - Device for pulling up single crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the amount of formation of COP and to avoid occurrence of heavy metals or the like with high pulling up speed and with a simple structure by arranging a radiation shield comprising quartz members wherein the thermal conductivity of the upper part is lower than that of the lower part, at a region where a single crystal is pulled up from a molten liquid via a seed crystal in a crucible. SOLUTION: A silicon single crystal Ig is grown by filling a silicon raw material for a semiconductor in a quartz crucible 3 set in a furnace main body 2, then heating and melting the silicon raw material by a heater 4, bringing a seed crystal 8 into contact with the surface of a silicon molten liquid M while applying a magnetic field by a superconducting magnet 6, pulling up the single crystal through a wire 14 while rotating and further cooling the single crystal by allowing gaseous Ar to flow from the upper side. In the device 1 for pulling up the single crystal, a radiation shield 5 having an opening part for pulling up the single crystal and comprising an upper part of a truncated conical body being expanded at the upper side and the lower part of a cylindrical body is arranged. Furthermore, cooling of the single crystal is accelerated by constituting the upper part of the radiation shield 5 using an opaque quartz glass member having low thermal conductivity, and rapid cooling of the single crystal is prevented by constituting the lower part using a transparent quartz glass member having high thermal conductivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single crystal pulling apparatus, and more particularly to a single crystal pulling apparatus capable of pulling a single crystal at a high speed and reducing the amount of generated COP.

[0002]

2. Description of the Related Art In general, a silicon single crystal is mainly used for a substrate of a semiconductor device. This silicon single crystal is obtained by a Czochralski method (hereinafter, referred to as C) from polycrystalline silicon.
It is called Z method. ).

As shown in FIG. 11, in the CZ method, a quartz glass crucible 23 installed in a chamber 22 of a single crystal pulling apparatus 21 is filled with polysilicon as a raw material, and is provided on the outer periphery of the quartz glass crucible 23. The polysilicon is heated and melted by the heater 24, and the seed crystal 26 attached to the seed chuck 25 is immersed in the melt M, so that the seed chuck 2 is melted.
5 and the quartz glass crucible 23 are rotated in the same direction or in the opposite direction, while the seed chuck 25 is pulled up to remove the single crystal I.
It is a method of growing g.

In the single crystal pulling apparatus 21, a radiation shield 27 is provided around a single crystal pulling region above the quartz glass crucible 23. The radiation shield 27 has a lower opening 27d having a diameter of an upper opening 27u. The radiation shield 27 is integrally formed of the same material, and the material thereof is Ta or Mo.
And ceramics such as C and SiC.

In the single crystal pulling process using the single crystal pulling apparatus 21, the OSF (O
xidation-Induced Stacking
Fault) COP which is a crystal defect inside the ring
(Crystal Originated Parti
Cle) may occur, but this COP is one of the factors that deteriorate the oxide film breakdown voltage of the device, and it is necessary to reduce the COP.

The radiation shield 27 is formed of a silicon single crystal Ig from a polysilicon melt M, a quartz glass crucible 23 or the like.
The radiant heat applied to the silicon single crystal is cut off to promote cooling of the silicon single crystal Ig, thereby enabling the single crystal pulling speed to be increased and suppressing the generation of COP. Further, the radiation shield 27 is introduced from above the chamber. Argon gas is introduced from the center of the quartz glass crucible 23 through the periphery of the silicon single crystal Ig to the exhaust holes 30 provided in the bottom 29 of the chamber 22 through the peripheral edge, and S generated from the silicon melt M is generated.
It is installed for the purpose of eliminating gases that inhibit single crystallization, such as iO ₂ and metal vapor generated from the graphite crucible 31.

However, since the radiation shield 27 is entirely made of the same material and has a constant heat transfer coefficient, cooling of the silicon single crystal Ig is promoted over the entire temperature range, and C
The OP can be passed through the temperature range of 1250 ° C. to 1000 ° C. in which the OP grows in a short time, while the CO is rapidly cooled.
Even in a temperature range from the freezing point to 1300 ° C. where P is easily formed and slow cooling is required, the single crystal is rapidly cooled by the action of the radiation shield 17, so that a large amount of COP is generated and a wafer having a good oxide film breakdown voltage is obtained. Can not.

As a method of suppressing the COP, there is a method in which the pulling speed of the single crystal is reduced and the diameter of the OSF ring is shrunk to the inside of the crystal core. However, in this method, a large COP remains in the crystal core and the center of the wafer is reduced. There is a problem that the device yield in the portion is lowered, and the pulling speed is reduced, so that the productivity of pulling a single crystal is lowered and the crystal characteristics in a crystal plane are non-uniform.

Further, since the conventional radiation shield 27 is made of metal or ceramics as described above, there is a possibility that the silicon single crystal Ig is contaminated with heavy metals such as Fe and Cu.

In the single crystal pulling apparatus using the CZ method, a radiation shield comprising a frustoconical heat insulating cylinder surrounding the pulling region is provided above and near the silicon melt, and the radiation shield is divided into two parts. There is an example in which the heat insulation performance of the lower part of the shield is set lower than the heat insulation performance of the upper part of the shield (Japanese Patent Laid-Open No. 7-172971). In this conventional example, the portion surrounded by the lower shield receives radiant heat, the transit time in the high-temperature region can be extended, and after the device process, a wafer having a good oxide film breakdown voltage can be obtained. Since the single crystal surrounded by the radiation shield is cooled in the same manner as in the related art, the temperature region in which the frequency of occurrence of crystal defects is high can be quickly passed, and the occurrence of crystal defects can be reduced as in the conventional case.

However, this single crystal pulling apparatus has a C
It is not enough to reduce the OP, and the upper shield of the radiation shield has a three-layer structure of graphite and a heat insulating material made of graphite or ceramic fiber, so that the structure is complicated and the manufacturing cost increases. In addition, it is not possible to sufficiently remove contaminants of silicon single crystal such as heavy metals generated from radiation shield components, and furthermore, a large amount of inert gas is required for removal, thereby increasing production costs. There is.

[0012]

Therefore, a single crystal can be pulled at a high speed, the amount of COP generated can be reduced, the oxide film breakdown voltage can be improved, and the structure is simple and inexpensive. There has been a demand for a single crystal pulling apparatus having a radiation shield that does not generate heavy metals and the like.

The present invention has been made in view of the above-described circumstances, and is capable of pulling a single crystal at a high speed, and has a C
It is an object of the present invention to provide a single crystal pulling apparatus having a radiation shield that reduces the amount of OP generated, improves the withstand voltage of an oxide film, has a simple structure, is inexpensive, and does not generate heavy metals and the like from constituent members.

[0014]

Means for Solving the Problems According to the first aspect of the present invention, which has been made to achieve the above object, a crucible installed in a chamber and a semiconductor material filled in the crucible are heated to form a melt. And a radiation shield installed above the crucible so as to surround the pulling area. In the single crystal pulling apparatus for pulling a single crystal by immersing a seed crystal in a melt, the radiation shield has heat conduction. It is formed of a shield upper part and a shield lower part made of two kinds of quartz members with different rates,
The gist is to provide a single crystal pulling apparatus characterized in that the thermal conductivity at the upper part of the shield is smaller than the thermal conductivity at the lower part of the shield.

According to the invention of claim 2 of the present application, the radiation shield is a single crystal pulling apparatus according to claim 1, wherein the shield upper part is an opaque quartz member and the shield lower part is a transparent quartz member. The main point is.

According to the third aspect of the present invention, the single crystal pulling apparatus according to claim 1 or 2, wherein the radiation shield is formed so as to be divided into a shield upper part and a shield lower part. The gist is that.

In the invention of claim 4 of the present application, the shield upper part is a truncated cone having a hollow shape and the diameter of the upper opening is larger than the diameter of the lower opening, and the shield lower part is a hollow cylindrical body. The gist is a single crystal pulling apparatus according to any one of Items 1 to 3.

According to a fifth aspect of the present invention, the single crystal pulling apparatus according to any one of claims 1 to 4, wherein the lower portion of the shield has a length of 20 to 100 mm. It is a gist.

According to the invention of claim 6 of the present application, the single crystal pulling apparatus includes a magnet for applying a magnetic field to the raw material melt. The gist is that it is a crystal pulling device.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a single crystal pulling apparatus according to the present invention will be described with reference to the accompanying drawings.

As shown in FIG. 1, a single crystal pulling apparatus 1 according to the present invention comprises a furnace main body 2 constituting a closed vessel, a quartz crucible 3 installed inside the furnace main body 2, A heater 4 is provided for heating the crucible 3 and melting a raw material supplied to the quartz crucible 3, for example, polysilicon to form a silicon melt M.

Above the quartz crucible 3, a pull-up region is surrounded to prevent heat radiation from the silicon melt M and to supply an inert gas, for example, argon gas (hereinafter referred to as Ar) flowing in the furnace main body 2. A radiation shield 5 for controlling the flow path is provided.

On the other hand, outside the furnace body 2, two normal-conducting or superconducting magnets (hereinafter referred to as “superconducting magnets”) 6 are arranged diametrically opposite each other so as to sandwich the furnace body 2. ,
Each superconducting magnet 6 is composed of a coil 6a, and is disposed such that a straight line connecting the center of the coil 6a is near the liquid surface of the silicon melt M.

Since the size and density of the COP generated in the single crystal Ig are greatly affected by the heat history at the time of pulling the single crystal, the radiation shield 5 for controlling the thermal effect of the single crystal Ig is devised.

For example, as shown in FIG. 2, the radiation shield 5 has a shield upper part 5u and a shield lower part 5u.
d, and the shield upper part 5u is connected to the lower opening part 5u.
The diameter of u1 is a truncated conical cylindrical body smaller than the diameter of the upper opening 5u2, and the shield lower part 5d is a hollow cylindrical body having an annular engaging ridge 5d1 at the upper end. The radiation shield 5 is made of the same material but has two types of quartz members having different thermal conductivity, for example, an upper shield portion 5u is an opaque quartz member (for example, having a thermal conductivity of 1.39 W / mK), and a lower shield portion 5d is transparent. It is formed of a quartz member (for example, having a thermal conductivity of 1.66 W / mK).
The opaque quartz member forming the shield upper part 5u is a quartz glass containing a large number of bubbles, and constitutes the shield lower part 5d, and has a lower thermal conductivity than a transparent quartz member which is a quartz glass containing almost no bubbles. The heat insulation performance is large, and therefore the heat insulation performance of the shield upper part 5u is larger than that of the shield lower part 5d.

The upper shield 5u and the lower shield 5
By setting d to an appropriate thickness, a desired heat insulating performance can be obtained.

The lower part 5d of the shield has a length of 20 to 100 m.
m, and the melt M and the lower shield 5
The distance between the lower end surfaces of d is preferably at least 30 mm or less, preferably 10 mm. In this case, the size of the COP is the smallest and the density is the lowest.

The radiation shield 5 is attached to the partition plate 7 by a mounting member (not shown) which does not hinder the flow of Ar gas.
Mounted on

Ar introduced from above the furnace body 2
Is discharged to the outside of the furnace main body 2 through the opening 9 through which the silicon single crystal Ig grown from the seed crystal 8 penetrates and the air passage 10 formed between the quartz crucible 3 and the heater 4. Thus, a plurality of, for example, two exhaust ports 12 are provided in the bottom portion 11 of the furnace main body 2.

Reference numeral 13 denotes a rotary shaft which is coupled to a motor (not shown) and rotates the quartz crucible 3. Reference numeral 14 denotes a pull-up which is provided with a seed chuck 15 at its tip and pulls up the grown silicon single crystal Ig upward. It is a wire.

Next, a method for pulling a single crystal using the single crystal pulling apparatus according to the present invention will be described.

The raw material polysilicon is placed in a quartz crucible 3, and Ar is allowed to flow into the furnace main body 2 from above the furnace main body 2.
The quartz crucible 3 is heated by the urging of the heater 4, and the rotating shaft 13 connected to the motor is rotated by the urging of the motor to rotate the quartz crucible 3.

After a certain period of time, the wire 14 is lowered, and the seed crystal 8 is brought into contact with the liquid surface of the silicon melt M. Thereafter, the coil 6a of the superconducting magnet 6 is energized to apply a magnetic field to the silicon melt. 4 near the liquid level.

As described above, single crystal Ig grows from seed crystal 8 in contact with melt surface M, and this single crystal Ig is pulled up at high speed through opening 9 provided in radiation shield 5. .

As described above, COP generated in single crystal Ig
The size and the density of the single crystal are greatly affected by the thermal history at the time of pulling the single crystal. Therefore, the radiation shield 5 for controlling the thermal effect of the single crystal Ig is devised. The single crystal Ig surrounded by the shield lower part 5d is made of a heater 4,
Radiant heat from the inner wall and the like of the quartz crucible 3 is transmitted well,
Since the high temperature region is expanded and the temperature of the single crystal Ig is maintained, the single crystal Ig is gradually cooled. Therefore, in the temperature range from the freezing point at which COP is generated to 1300 ° C., this single crystal I
g can extend the time of passing through this temperature region by the shield lower part 5d of the transparent quartz member. Therefore, the single crystal Ig can be gradually cooled, and the generation of COP can be suppressed.

Further, the single crystal Ig pulled up through the shield lower part 5d is pulled up through the shield upper part 5u. The upper shield 5u is formed of an opaque quartz member and has a low thermal conductivity and a high heat insulation performance. Therefore, the single crystal Ig surrounded by the upper shield 5u is
Further, heat is shut off from the surroundings, and the single crystal Ig is rapidly cooled. Therefore, 1250 ° C. to 1000 ° C. where the COP grows
By using the shield upper part 5u of the opaque quartz member, the time required for the single crystal Ig to pass through this temperature range can be shortened in the temperature range up to. Therefore, the single crystal Ig is rapidly cooled, the growth of the slightly contained COP can be suppressed, and the size of the COP can be reduced.

The radiation shield 5 includes a shield lower part 5d having a large thermal conductivity and a shield upper part 5u having a small thermal conductivity.
Therefore, even if the crystal is pulled at a high speed, the generation and growth of COP can be suppressed, and the productivity of pulling a single crystal can be increased.

Further, the silicon melt I was removed from the quartz crucible 3.
It is considered that the oxygen eluted in g is taken into the silicon single crystal Ig and affects the generation of COP, and it is necessary to suppress the amount of oxygen taken into the single crystal Ig. Therefore, by applying a magnetic field to the silicon melt M that causes convection in the quartz crucible 3 in a molten state at right angles to the convection, the electromotive force increases the effective kinematic viscosity coefficient, so that convection is suppressed. By suppressing this convection, the quartz crucible 3
Oxygen eluted from the silicon melt M into the silicon melt M can be suppressed, and the oxygen taken into the silicon single crystal Ig can be considerably reduced. Therefore, the generation of COP can be more effectively suppressed by a synergistic effect with the radiation shield 5. Can be.

In the single crystal pulling step, a shield upper part 5 u and a shield lower part 5 forming the radiation shield 5 are formed.
Since both d are made of a quartz member, they are of high purity, do not generate heavy metals and contaminate the single crystal Ig, and can improve the oxide film breakdown voltage. Furthermore, since heavy metals are not generated unlike the conventional radiation shield, not only is there no contamination by heavy metals and a high single crystallization rate is obtained, but also the Ar flow rate flowing through the furnace body 2 to discharge heavy metals is reduced. Can be reduced, and pulling costs can be reduced.

Further, in the single crystal pulling step, the Si melt adheres to the radiation shield 5 and it is necessary to perform periodic cleaning. However, it is difficult to prevent heavy metal contamination from accumulating like the conventional SiC radiation shield. Is different, upper shield 5u
Since is made of opaque quartz, it can be easily washed only by dipping in acid, and the total pulling cost can be reduced.

Further, the radiation shield 5 has a shield upper part 5u.
And the shield lower part 5d, it is easy to attach and detach, and easy to clean.

[0042]

Test 1: The temperature of each part of a silicon single crystal was measured using a single crystal pulling apparatus according to the present invention as shown in FIG. Lower shield length 80m as measurement condition
m, and the distance between the lower end of the lower shield and the liquid surface was 10 mm. FIG. 4 shows the results. In the conventional example, a conventional radiation shield was used, and pull-up measurement was performed in the same manner as in the example.

In the embodiment, in the temperature range from the freezing point to about 1300 ° C. (between the liquid level and about 110 mm from the liquid level), the temperature is gradually lowered (slowly cooled), and the temperature range (about 1300 ° C. to about 1000 ° C.) From about 110 mm to 160 mm), the temperature was rapidly lowered (rapidly cooled).

In the conventional example, it was found that the temperature dropped at the same rate in each temperature region (at any distance of the single crystal).

Test 2: Using a single crystal pulling apparatus according to the present invention, pulling a silicon single crystal by changing the length of the upper shield part (quartz tube), the size and number of COPs in the silicon single crystal Was measured. FIG. 5 shows the results.

The length of the quartz tube is 20 to 100 m
It was found that the size and the number of COPs were the minimum values in the range of m.

Test 3: Using a single crystal pulling apparatus according to the present invention, the silicon single crystal was pulled while changing the pulling speed, and the number of COPs in the silicon single crystal was measured. FIG. 6 shows the results. In the conventional example, a conventional radiation shield was used, and the speed was changed and the pull-up measurement was performed as in the example.

In the embodiment, CO is drawn over the entire pulling speed range.
The number of P is small, especially at 1.2 mm / min or less.

On the other hand, in the conventional example, the number of COPs is large over the entire pulling speed range, and particularly increases rapidly at 1.4 mm / min or more.

Test 4: The silicon single crystal was pulled using the single crystal pulling apparatus according to the present invention while changing the Ar gas flow rate, and the amount of Fe contamination in the silicon single crystal was measured. FIG. 7 shows the results. In the conventional example, pull-up measurement was performed using a conventional radiation shield in the same manner as in the example.

In the embodiment, over the entire range of the Ar gas flow rate,
It was found that the amount of Fe contamination was small.

In the conventional example (SiC), A
It was found that the amount of Fe contamination was small over the entire range of the flow rate of the r gas.

It was found that the Fe contamination amount was large over the entire range of the Ar gas flow rate in each of the conventional example (C), the conventional example (Mo), and the conventional example (Ta).

Test 5: The amount of Fe contamination in the silicon single crystal was measured using the radiation shield after washing in the single crystal pulling apparatus according to the present invention. FIG. 8 shows the results. In the conventional example, a pull-up measurement was performed in the same manner as in the example, using a radiation shield made of SiC.

In the embodiment, the amount of Fe contamination is small from the first use, and the amount of Fe contamination does not increase even if the number of uses is increased.

In the conventional example, it was found that the amount of Fe contamination was large from the first use, and that sufficient cleaning could not be performed. Further, it was found that the state in which the amount of Fe contamination was large continued even if the number of uses was increased.

Test 6: Ten silicon single crystals were pulled using the single crystal pulling apparatus according to the present invention, and the single crystallization ratio was measured. FIG. 9 shows the average value of 10 samples.

The conventional examples are made of SiC, C, Mo,
Using a radiation shield made of Ta, pull-up measurement was performed in the same manner as in the example.

The example showed a high single crystallization ratio of about 95%.

In the conventional example, the radiation shield made of SiC is about 8
Although a relatively high value of 5% was shown, the radiation shields made of C, Mo, and Ta all showed low values.

Test 7: A silicon wafer was manufactured from a silicon single crystal pulled using the single crystal pulling apparatus according to the present invention, and an oxide film was formed by heat treatment. The oxide film withstand voltage was measured and passed the standard. The yield of what was done was checked. The results are shown in FIG. The conventional example uses a radiation shield made of SiC and forms an oxide film withstand voltage in the same manner as in the embodiment.

The example showed an extremely high yield of 95%.

The conventional example was found to be 70%, which is significantly inferior to the embodiment.

[0064]

According to the apparatus for pulling a single crystal according to the present invention, a single crystal can be pulled at a high speed, the amount of generated COP can be reduced, the withstand voltage of an oxide film can be improved, and the cost can be reduced.
A single crystal pulling apparatus having a radiation shield that does not generate heavy metals or the like from constituent members can be provided.

That is, the radiation shield has two different thermal conductivity.
It is formed of the upper and lower shields made of various kinds of quartz members, and the thermal conductivity of the upper shield is lower than the thermal conductivity of the lower shield.
In the temperature range of 1300 ° C., the time required for the single crystal to pass through the temperature range can be extended by the lower portion of the shield of the transparent quartz member, the single crystal can be gradually cooled, and the generation of COP can be suppressed. In addition, 1250 ° C. where COP grows
In the temperature range of １０００1000 ° C., the single crystal can be shortened in the time required to pass through the temperature range by the shield upper part of the opaque quartz member, and the single crystal can be rapidly cooled.
The growth of OP can be suppressed, and the size of COP can be reduced. Therefore, the amount of generated COP can be reduced, the size of the slightly contained COP can be reduced, and the oxide film breakdown voltage can be improved. Further, even if the crystal is pulled at a high speed, the generation and growth of COP can be suppressed, and the productivity of pulling a single crystal can be increased. Furthermore, the radiation shield is of high purity and generates heavy metals to produce single crystal I
g, without contaminating the oxide film, improving the withstand voltage of the oxide film. In addition to obtaining a high single crystallization rate without contamination by heavy metals, the flow rate of Ar flowing through the furnace body to discharge the heavy metals is reduced. Can be reduced, and raising costs can be reduced. Furthermore, the Si melt adheres to the radiation shield, and it is necessary to periodically clean it. However, since the upper part of the shield is made of opaque quartz, it can be easily cleaned only by immersion in acid, and the total pulling up Cost can be reduced.

In the radiation shield, since the upper part of the shield is made of an opaque quartz member and the lower part of the shield is made of a transparent quartz member, the heat conductivity is easily different, and the heat conductivity of the upper part of the shield is smaller than that of the lower part of the shield. can do.

Further, since the radiation shield is formed so as to be divided into an upper part and a lower part of the shield, the radiation shield can be easily attached and detached and can be easily cleaned.

Further, since the upper part of the shield is a truncated cone having a hollow shape and the lower part of the shield is a cylindrical body having a hollow shape, a temperature range of slow cooling and rapid cooling can be easily realized.

The length of the lower part of the shield is 20 to 100.
mm, both the size and the number of COPs can be reduced.

Further, since the single crystal pulling apparatus is provided with a magnet for applying a magnetic field to the raw material melt, the amount of oxygen contained in the single crystal is reduced, and the COP is more effectively reduced by the synergistic effect with the radiation shield. Can be suppressed.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a single crystal pulling apparatus according to the present invention.

FIG. 2 is a longitudinal sectional view of a radiation shield used in the single crystal pulling apparatus according to the present invention.

FIG. 3 is an explanatory view of a single crystal pulling apparatus used in the embodiment.

FIG. 4 is a test result diagram showing a relationship between a distance from a melt surface of the single crystal and a temperature change in pulling the single crystal using the single crystal pulling apparatus according to the present invention.

FIG. 5 is a test result diagram showing a relationship between a change in a quartz tube length and a COP size and number in pulling a single crystal using the single crystal pulling apparatus according to the present invention.

FIG. 6 is a test result diagram showing a relationship between a change in a pulling speed and the number of COPs in pulling a single crystal using the single crystal pulling apparatus according to the present invention.

FIG. 7 is a test result diagram showing a relationship between a change in Ar gas flow rate and an amount of Fe contamination in pulling a single crystal using the single crystal pulling apparatus according to the present invention.

FIG. 8 is a test result diagram showing a relationship between the number of uses of a radiation shield after cleaning and the amount of Fe contamination in pulling a single crystal using the single crystal pulling apparatus according to the present invention.

FIG. 9 is a view showing a result of measuring a DF ratio of a silicon single crystal in pulling a single crystal using the single crystal pulling apparatus according to the present invention.

FIG. 10 is a view showing a result of withstand voltage of an oxide film of a silicon wafer manufactured from a pulled silicon single crystal in pulling a single crystal using the single crystal pulling apparatus according to the present invention.

FIG. 11 is a longitudinal sectional view of a conventional single crystal pulling apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Single crystal pulling apparatus 2 Furnace main body 3 Quartz crucible 4 Heater 5 Radiation shield 5d Shield lower part 5d1 Engagement ridge 5u Shield upper part 5u1 Upper opening part 5u2 Lower opening part 6 Superconducting magnet 6a Coil 7 Partition plate 8 Seed crystal 9 Opening Part 10 Ventilation path 11 Bottom part 12 Exhaust port 13 Rotation axis 14 Wire 15 Seed chuck Ar Argon gas Ig Silicon single crystal M Silicon melt

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[Procedure amendment]

[Submission date] December 8, 1999 (1999.12.
8)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] FIG.

[Correction method] Change

[Correction contents]

FIG. 11

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Masakatsu Kojima 30 Soya, Hadano-shi, Kanagawa F-term in Hadano Plant, Toshiba Ceramics Co., Ltd. DD01 FF04 GG01 HH10 RR03

Claims (6)

[Claims] 1. A crucible installed in a chamber, a heater for heating a semiconductor material filled in the crucible to melt the semiconductor material, and a radiation seal installed above the crucible so as to surround a pulling region. In a single crystal pulling apparatus having a seed crystal immersed in a melt and pulling a single crystal, the radiation shield is formed of a shield upper part and a shield lower part made of two kinds of quartz members having different thermal conductivities. A single crystal pulling device, wherein the thermal conductivity of the single crystal is lower than the thermal conductivity of the lower part of the shield. 2. The single crystal pulling apparatus according to claim 1, wherein the radiation shield has an opaque quartz member at an upper portion of the shield and a transparent quartz member at a lower portion of the shield. 3. The single crystal pulling apparatus according to claim 1, wherein the radiation shield is formed so as to be divided into a shield upper part and a shield lower part. 4. The shield upper part is a truncated cone having a hollow shape and a diameter of an upper opening is larger than a diameter of a lower opening, and the shield lower part is a hollow cylindrical body.
4. The single crystal pulling apparatus according to any one of claims 1 to 3. 5. The shield lower part has a length of 20 to 100.
The single crystal pulling apparatus according to any one of claims 1 to 4, wherein the diameter is mm. 6. The single crystal pulling apparatus according to claim 1, wherein the single crystal pulling apparatus includes a magnet for applying a magnetic field to the raw material melt.