JPH11130585A - Apparatus for pulling single crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for pulling a single crystal capable of accurately monitoring the growth control of a neck with a high accuracy, reproducibility of dimensional accuracy of the shape of a supporting part for supporting a crystal and the diameter of a large-caliber single crystal and suitable for pulling the large-caliber single crystal. SOLUTION: This apparatus for pulling a single crystal comprises the first two-dimensional camera 15 focusing on a neck growth region An for growing a single crystal, the second two-dimensional camera 16 focusing on a straight drum part for growing the single crystal and a means 17 for changing over an image signal for controlling the shape capable of changing pulling conditions during a period from the completion of the neck growth of the grown single crystal to the start of the growth of the straight drum part from an image signal of the first two-dimensional camera 15 to that of the second two-dimensional camera 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a single crystal pulling apparatus, and more particularly to a single crystal pulling apparatus suitable for pulling a large-diameter single crystal.

[0002]

2. Description of the Related Art In general, a silicon wafer is manufactured from polycrystalline silicon by the Czochralski method (hereinafter referred to as C).
It is called Z method. ) To produce a silicon single crystal ingot, and cut the ingot to a predetermined thickness by a slicing machine to produce a silicon wafer.

[0003] However, in order to reduce the manufacturing cost of semiconductor devices and the like, silicon wafers are required to have a large diameter, and accordingly, silicon single crystals used as materials for silicon wafers are also required to have a large diameter.

Conventionally, a silicon single crystal pulling apparatus 30 by the CZ method has a quartz crucible 32 provided in a water-cooled furnace body 31 as shown in FIG. The quartz crucible 32 is held by a graphite crucible 33, and the graphite crucible 33 is supported by a crucible rotating shaft 34 that can rotate and move up and down.

[0005] Polysilicon as a raw material supplied into the quartz crucible 32 is heated by a heater 35 provided so as to surround the quartz crucible 32 to become a silicon melt M. Pull-up wire 38 via wire reel rotating device 37
Are suspended on the center line of the quartz crucible 32. A seed 40 is held at the tip of the lifting wire 38 via a seed chuck 39.

[0006] The tip of the seed 40 is brought into contact with the silicon melt M, and after being blended, lifting is started. For dislocation-free growth, it is necessary to form a long neck N of several mm long.

Thereafter, the crystal is gradually grown (thickened), and the process proceeds to the crystal growth of the straight body portion S through the growth of the crown C.

The seed 40 is also rotatable and vertically movable. The shape of the grown crystal is monitored by a one-dimensional camera (line image sensor) whose imaging range extends from the center to the periphery of the quartz crucible 32 through a camera port 41 or a two-dimensional camera (area sensor camera) 42 having a wide imaging range. The pulling conditions are adjusted using the power supplied to the heater 35, the single crystal pulling speed, and the like as parameters based on the signal.

In such a single crystal pulling apparatus 30, the single crystal to be pulled grows as a crown (cone part) from a relatively small seed diameter to a large diameter from a relatively small seed diameter to a straight body (body). The imaging range of the diameter monitor is
It is necessary to set a relatively wide range from the rotation center of the single crystal to the periphery.

When the imaging range of the diameter monitor is set to a relatively wide range from the rotation center of the single crystal to the periphery, the growth of a portion having a large diameter, such as a straight body, is determined by the diameter signal of the diameter monitor. Although sufficient resolution can be obtained,
In the growth of a seed having an extremely small diameter and an initial portion of the crown, the resolution is insufficient and it is difficult to accurately raise the seed.

As a solution to this problem, there is a method in which a two-dimensional camera is used by zooming up when growing a single crystal having a small diameter. In pulling a relatively small diameter single crystal up to 200 mm in diameter, there is a method. There was no problem with this method.

However, a large diameter, for example, a diameter of 300
When the diameter becomes large, such as mm or 400 mm, in the zoom-up method in which the two-dimensional camera focuses on the small diameter portion, there is a problem that the resolution of the peripheral portion having the large diameter is reduced.

When pulling a large-diameter single crystal,
Since the pulling speed decreases, it is effective to use a radiation shield to shield the radiant heat from the surface of the quartz crucible or silicon melt to the crystal to prevent the single crystal pulling speed from lowering. At the time when the diameter of the base and the single crystal has spread to the straight body, it is impossible to monitor with a two-dimensional camera for the diameter from the rotation center of the single crystal to the periphery due to the radiation shield.

In such a case, even if the control of the small diameter portion is sacrificed to some extent, the focus of the two-dimensional camera is focused on the arc portion of the straight body portion within the imaging range, and the arc is formed into a perfect circle image. Then, a method of reading the diameter from the perfect circle is used.

Further, as disclosed in Japanese Patent Application Laid-Open No. 58-135197, two two-dimensional cameras are used, and a neck portion having a small diameter uses a first two-dimensional camera. A method in which the second two-dimensional camera is used together when the camera deviates from the field of view of the camera,
As disclosed in Japanese Patent No. 6509, there is a method of using a two-dimensional camera for a neck part having a small diameter and selectively using a one-dimensional camera when the diameter becomes large.

However, in any of these methods, it is necessary to accurately measure both a portion having a large diameter such as a straight body portion of a single crystal and an extremely small diameter portion such as a neck portion of a single crystal having a large diameter. Insufficient for puller monitor.

According to the results of the study by the present inventors, the weight of the single crystal is 200 kg or more and the diameter is 300 mm or 400 mm.
When pulling a large diameter single crystal, the conventional 2 mm
With a neck having a diameter of 3 mm or less, the load resistance is insufficient, the neck needs to be thickened to about 6 mm, and it is necessary to raise the neck long at a constant neck diameter for dislocation-free growth. It was also found that high-precision neck growth control was necessary.

On the other hand, as a measure against the weight of the neck portion in pulling a heavy single crystal, a crown portion of the pulled single crystal is once squeezed to form a bump-shaped support portion, and a support device for supporting a crystal is provided at the support portion. A method has been proposed in which the crystal is pulled up.In this method, the conventional neck control is sufficient, but in the case of a method of pulling up the crystal by supporting the crystal using this support, It has been found that reproducibility of the dimensional accuracy of the shape of the support portion is necessary in order to grasp the grown crystal via the support portion with the support device for the crystal by remote control from outside the furnace body.

Therefore, as described above, in order to control the growth of the neck with high accuracy, the reproducibility of the dimensional accuracy of the shape of the supporting portion for the crystal, and the diameter control of the single crystal having a large diameter, the single crystal pulling which can be accurately monitored. An upper device was desired.

The present invention has been made in view of the above-described circumstances, and has a high-accuracy neck growth control, reproducibility of the dimensional accuracy of the shape of a supporting portion for supporting a crystal, and accurate determination of the diameter of a large-diameter single crystal. An object of the present invention is to provide a single crystal pulling apparatus which can be monitored and is suitable for pulling a large diameter single crystal.

[0021]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the invention of claim 1 of the present application captures an image of a boundary portion between a silicon melt and a grown single crystal by a two-dimensional camera. In a single crystal pulling apparatus based on the Czochralski method for controlling the diameter of a grown single crystal based on an image signal, a first two-dimensional camera that focuses on a neck growth region, images a boundary portion, and outputs an image signal; A second two-dimensional camera that focuses on the torso growth region and captures an image of the boundary portion and outputs an image signal, and shape control that changes the pulling condition between the end of the neck growth of the grown single crystal and the start of the straight torso growth The subject matter of the present invention is a single crystal pulling apparatus characterized by comprising means for switching an image signal for use from an image signal of a first two-dimensional camera to an image signal of a second two-dimensional camera.

According to a second aspect of the present invention, the first two-dimensional camera is mounted at a lower position than the second two-dimensional camera, and the optical axes of the first two-dimensional camera and the second two-dimensional camera are crossed. The gist of the present invention is a single crystal pulling apparatus according to claim 1.

According to a third aspect of the present invention, there is provided a single crystal pulling apparatus according to the first aspect, wherein a radiation shield for shielding radiant heat from the surface of the silicon melt to the crystal is provided. .

[0024] The invention of claim 4 of the present application is characterized in that the first two-dimensional camera captures an image of a step of growing a neck, growing a bump-shaped support provided on the neck, and growing a single crystal in the initial stage of a crown. The gist is a single crystal pulling apparatus according to claim 1.

According to a fifth aspect of the present invention, an image signal is transmitted from the first two-dimensional camera to the second two-dimensional camera when the diameter of the bump-shaped support portion and the diameter of the crown of the grown single crystal become substantially the same. The gist is a single crystal pulling apparatus according to claim 4, wherein the apparatus is switched.

[0026]

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. FIG. 1 shows a single crystal pulling apparatus 1 according to the present invention. The pulling apparatus 1 comprises a water-cooled furnace body 2 and a quartz crucible which melts polysilicon as a raw material stored in the furnace body 2 into molten silicon M. 3 and a graphite crucible 4 holding the quartz crucible 3
And a heater 5 surrounding the graphite crucible 4. The graphite crucible 4 penetrates the furnace body 2, is connected to a motor 6, is rotated, and is attached to a crucible rotating shaft 8 that is raised and lowered by a lifting device 7.

A seed chuck 10 for holding a seed 9 for pulling a single crystal is provided above the quartz crucible 3.
There is provided a pulling wire 11 to which is attached.

Further, the wire 11 is provided outside the furnace body 2 and is equipped with a wire rotating device 12 which is urged by a motor (not shown) to wind up and rotate the wire 11.

Further, on the outer wall of the shoulder 2a of the furnace body 2, there are provided a first camera port 13 and a second camera port 14 which are capable of transmitting light by closing the through holes with heat resistant glass. The first camera port 13 is provided at a position lower than the second camera port 14 on the outer wall of the shoulder 2a.

An optical axis L1 penetrating the first camera port 13
The first two-dimensional camera 15 having the optical axis L2 penetrating through the second camera port 16 is installed so that the focal point is set to the neck growth region.
Numeral 4 is set in accordance with the straight body growth area As.
In the crucible 3 of the furnace body 2, the neck growth region An is always inside (core side) the straight body growth region As.
The optical axis L1 of the first two-dimensional camera 15 provided at a lower position on the outer wall of the camera and the optical axis L2 of the second two-dimensional camera 16 provided at a higher position than the first two-dimensional camera 15 always intersect. .

The first two-dimensional camera 15 can finely adjust the focal point in accordance with the position of the quartz crucible 3 in the axial direction and the level of the melt surface which changes depending on the charge amount of the raw material. The first two-dimensional camera 16 moves the target diameter of the single crystal (200 m
m, 300 mm, 400 mm, etc.).

The first two-dimensional camera 15 and the second two-dimensional camera 16 are connected to a changeover switch 17, and the changeover switch 17 causes the image signals of the first two-dimensional camera 15 and the second two-dimensional camera 16 to be changed to one of them. One of them is selectively supplied to the binarization circuit 18.

The changeover switch 17 is a first two-dimensional camera 15
Controlling the diameter of the grown crystal using the image signal from
The selection control is performed by using the image signal from the second two-dimensional camera 16 to control whether the diameter of the grown crystal is controlled or not, and is controlled by the switch control circuit 19. The input voltage is binarized by the binarization circuit X and supplied to the image processing device 20,
Image processing is performed by the image processing device 20 to detect and output the diameter of the grown crystal.

This output is supplied to a controller 21 for controlling the amount of electric power supplied to the heater 5 for controlling the temperature of the silicon melt, a motor controller 23 for controlling the rotation speed of the quartz crucible 3, a quartz controller, The elevator controller 24 for controlling the height of the crucible 3 and the wire reel rotating device controller 25 for controlling the pulling speed and rotation speed of the grown crystal are controlled. By controlling these controllers 22, 23, 24, 25, etc., the pulling conditions are changed and the diameter of the grown crystal is controlled.

It is to be noted that at which stage of crystal growth the switching of the image signal to be used is programmed in the control device 21 in advance, and the control device 21 transmits a switching signal to the switch control circuit 19.

Since the single crystal pulling apparatus according to the present invention has the above-described structure, for example, in order to pull up a silicon single crystal having a diameter of 310 mm in consideration of a cutting allowance for a wafer having a diameter of 300 mm, a nugget-like polysilicon is required. Is put into the quartz crucible 3, and the lifting operation is automatically performed by a programmed lifting process.

On the other hand, the first two-dimensional camera 15 focuses on a position deviated outward by 3 mm from the center of the quartz crucible 3 and starts pulling up since the neck growth region An, for example, the diameter of the neck is 6 mm. From the point in time, the power is turned on so that imaging can be performed.

The second two-dimensional camera 16 focuses, for example, on a position deviated 155 mm outside from the center of the quartz crucible 3, and keeps the power supply that cannot image at the start of pulling off.

After the completion of the preparation for lifting, an inert gas, for example, argon gas is caused to flow into the furnace body 2 from above the furnace body 2,
The quartz crucible 3 is heated by energizing the heater 5 and the motor 6 is energized to rotate the crucible rotating shaft 8 coupled to the motor 6 to rotate the quartz crucible 3.

After a certain period of time, the wire 11 is lowered, and the seed 9 is brought into contact with the liquid surface of the silicon melt M to be blended.

After that, the lifting is started, and FIG.
The neck growth area An is monitored by the first two-dimensional camera 15 as described above.

The image signal of the first two-dimensional camera 15 is 2
The input voltage from the binarizing circuit 18 is further binarized, and further supplied to the image processing unit 20, where the image processing is performed by the image processing unit 20, and a bottleneck for dislocation-free growth is obtained. The diameter d1 of N is detected and output.

The output from the image processing device 20 is supplied to a control device 21 where a heater controller 22, a motor controller 2
3. By controlling the lifting device controller 24 and the wire reel rotating device controller 25, the neck N having a diameter d1 of 6 mm is continuously pulled up to a certain length l, for example, 300 mm.

When the neck N becomes 300 mm, the heater controller 22 and the motor controller 2 are controlled by the process program incorporated in the controller 21 through the controller 21.
3, the lifting device controller 24 and the wire reel rotating device controller 25 are controlled to pull up the single crystal as shown in FIG.
The process for manufacturing a crown C shown in FIG.

The crown growth area Cn is monitored by the first two-dimensional camera 12, and the image signal from the first two-dimensional camera 15 is converted into a binarizing circuit 18, a binarizing circuit 18, and an image processing device 20.
Is supplied to the control device 21 via the.

The heater controller 22, the motor controller 23, the elevator controller 24,
Further, the controller controls the wire reel rotating device controller 25 to control the pulling condition so that the diameter of the grown crystal is gradually increased and the crown C is formed.

Further, the pulling is continued, the crown C is grown, and the image signal from the first two-dimensional camera 15 at the time when the diameter of the crown C reaches 200 mm is converted into a binarization circuit 1.
8. Control device 21 as output via image processing device 20
Supplied to

The control device 21 includes a switch control circuit 19
Is operated to switch the second two-dimensional camera 16 from the stopped state to the operating state, while the first two-dimensional camera 15 is changed from the operating state to the stopped state. That is, 2
The image signal to the value conversion circuit 18 is switched from the image signal of the first two-dimensional camera 15 to the image signal of the second two-dimensional camera 16.

When the output of the state in which the diameter of the crown C is 200 mm is supplied in advance to the control device 21 as shown in FIG. 2B and K1 in FIG.
A switch control circuit 19 for switching the monitor of the growth area from the first two-dimensional camera 15 to the second two-dimensional camera 16
The program which controls is installed.

Further, the pull-up is continued under the monitor of the growth area by the second two-dimensional camera 16, and the growth of the crown C is continued.

As shown at point P3 in FIG. 3, the image signal from the second two-dimensional camera 13 at the time when the diameter d3 of the crown C reaches 310 mm is transmitted via the binarization circuit 18 and the image processing device 20. The output is supplied to the control device 21.

The heater controller 22, the motor controller 23, the elevating device controller 24,
Further, the controller 25 controls the wire reel rotating device controller 25 to control the pulling condition so that the straight body S is formed while maintaining the diameter of the grown crystal at 310 mm.

That is, as shown in FIG. 3, the monitoring of the single crystal growth region by the two two-dimensional cameras 15 and 16 is switched in accordance with the progress of the single crystal pulling process, and the process of pulling points P1 to P2 (neck) Area) and point P1
The first two-dimensional camera 15 monitors the point K1 until the point K1 in the process (crown region) from the point P2 to the point K1.
The processes of the crown region after the switching in 1 and the straight body region after the point P3 are performed by the second two-dimensional camera 16.

In the embodiment of the present invention, the switching from the first two-dimensional camera 15 to the second two-dimensional camera 16 is programmed in the control device 21 in advance. The controller 21 is programmed to execute the processing when the difference between the read diameter and the target diameter value at that time matches the difference between the read diameter of the second two-dimensional camera 16 and the target diameter value of the first two-dimensional camera 16. You may make it.

Subsequently, the pulling condition is maintained, a straight body portion having a predetermined length is formed, and the pulling is completed.

25 mm with a neck diameter of 6 mm ± 0.1 mm, a neck length of 300 mm, and a straight body diameter of 310 mm ± 5 mm.
0 kg of a single crystal was obtained.

The monitor of the crystal growth region is performed using two two-dimensional cameras, and the monitor of the two two-dimensional cameras is switched between the end of the neck growth of the single crystal and the start of the growth of the straight body portion. In particular, by focusing the two-dimensional camera on the neck region and the straight body region, which are important for growing a single crystal, both growth regions can be precisely monitored.

Therefore, it is possible to obtain a silicon single crystal whose shape is precisely controlled.

Next, another embodiment of the single crystal pulling apparatus according to the present invention will be described with reference to FIG.

A radiation shield 26 is provided above the quartz crucible 3 of the pulling apparatus 1 shown in FIG. 1 to shield radiant heat from the surface of the quartz crucible 3 and the silicon melt M to the crystal and to prevent a drop in the single crystal pulling speed. Have been.

The radiation shield 26 is installed so as not to block the optical axis L1 of the first two-dimensional camera 15 whose focus is set on the neck growth region.

When pulling is performed by the single crystal pulling apparatus 1 of the present embodiment, the crown C at the point k2 in FIG.
mm from the first two-dimensional camera 15 to the second
Switching to the two-dimensional camera 16 is performed.

When the crown C has grown to 150 mm, the monitor is switched from the two-dimensional camera 15 to the two-dimensional camera 16, and the radiation shield 26 obstructs the monitor of the first two-dimensional camera 15. The monitoring of the growth area can be reliably performed by the second two-dimensional camera 16.

If the radiation shield 26 blocks the optical axis L1 of the first two-dimensional camera 15 due to the height of the radiation shield 26 or the like, a part of the radiation shield 26 corresponding to the optical axis L1 is required. A small through-hole capable of transmitting light, or a through-hole such as a slit may be provided in the light emitting element. Since the opening area of the through hole is small, the function of the radiation shield 26 is not reduced.

In the single crystal pulling apparatus according to the present embodiment, the growth region can be reliably monitored in spite of the provision of the radiation shield 26, so that the silicon single crystal whose shape is controlled with high precision is provided. Can be obtained.

As in the case where the single crystal pulling apparatus according to the embodiment shown in FIG.
± 0.1mm, neck length 300mm, straight body diameter 3
A single crystal of 250 kg was obtained at 10 mm ± 5 mm.

Further, the single crystal pulling apparatus according to the present invention shown in FIG. 4 is provided with a pair of support members 27 which are controlled to be opened and closed from the outside to the wire 11 of the pulling apparatus 1 shown in FIG.
A support device 27 for supporting a crystal having a and 27b is provided.

As a measure against the weight of the neck N portion in pulling a heavy single crystal, the neck crown in pulling the single crystal is once narrowed to form a bump-shaped support portion T, and this support portion T is supported by the support device 27. Things.

In order to accurately control the shape of the bump-shaped support portion T, it is desirable that the second two-dimensional camera 16 is also mounted at a position as low as possible so that the grown crystal can be viewed from the side.

The pulling by the single crystal pulling apparatus of the present embodiment is performed in the same manner as the pulling by the single crystal pulling apparatus of the embodiment based on FIG.

When the neck N becomes 300 mm, the process for manufacturing the crown C is started.

The crown growth area Cn is monitored by the first two-dimensional camera 15, and as shown in FIG. 5, the image signal at the time when the diameter d4 of the crown C becomes 50 mm (point K3 in FIG. 5) is the first two-dimensional camera. The control device 21 is supplied from the dimensional camera 15 via the binarization circuit 18 and the image processing device 20. The output from the controller 21 controls the heater controller 22, the motor controller 23, the elevating device controller 24, and the wire reel rotating device controller 25, and squeezes the crown C so that the diameter of the grown crystal becomes smaller sequentially. . The crown C forms a bump-shaped support portion T.

The heater controller 22, the motor controller 23, the elevating device controller 24, and the wire reel rotating device controller 25 are output from the control device 21 based on the image signal at the time when the diameter of the crown C is reduced to 25 mm. And the pulling conditions are controlled to gradually increase the diameter of the grown crystal again to form the crown C.

Further, the pulling is continued, the crown C is grown, and the image signal from the first two-dimensional camera 15 at the time when the diameter of the crown C becomes 50 mm is converted to a binarization circuit 18.
The output is supplied to the control device 21 via the image processing device 20. The control device 21 controls the switch control circuit 19 to operate the changeover switch 17, activates the second two-dimensional camera 16, and converts an image signal to the binarization circuit 18 into an image from the second two-dimensional camera 16. Switch to signal.

Regardless of the switching of the monitor from the first two-dimensional camera 15 to the second two-dimensional camera 16, the same pulling up as in FIG. 1 is continued.

By switching from the first secondary camera installed at a lower position to the second secondary camera installed at a higher position at the time when the diameter of the crown C is 50 mm, the radiation shield 26 and the bumpy T Accordingly, the fields of view of the first secondary camera 15 and the second secondary camera 16 are not obstructed, and both growth areas can be monitored precisely. Therefore, the shape can be accurately controlled. Straight body diameter is 310m
A single crystal of 200 kg was obtained at m ± 5 mm.

[0077]

As described above, in the single crystal pulling apparatus according to the present invention, two two-dimensional camera monitors are switched between the end of single crystal neck growth and the start of straight body growth. In particular, by focusing the two-dimensional camera on the neck region and the straight body region, which are particularly important for growing a single crystal, both growth regions can be precisely monitored.

Accordingly, it is possible to provide a single crystal pulling apparatus capable of manufacturing a single crystal in which the shapes of the neck, the bump-shaped support portion, and the straight body portion of the single crystal are controlled with high accuracy.

Further, by switching from the first secondary camera installed at a lower position to the second secondary camera installed at a higher position, the field of view of the secondary camera is blocked by a radiation shield and a bump-shaped support. Without monitoring, both growth regions can be monitored precisely. Therefore, it is possible to provide a single crystal pulling apparatus which can use a radiation shield and is suitable for pulling a large-diameter single crystal requiring a bump-shaped support.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a single crystal pulling apparatus according to the present invention.

FIG. 2 is an explanatory view showing a pulled state of the single crystal according to FIG. 1;

FIG. 3 is an explanatory diagram at the time of switching a monitor of the two-dimensional camera used in FIG. 1;

FIG. 4 is a schematic diagram of a single crystal pulling apparatus according to another embodiment of the present invention.

FIG. 5 is an explanatory diagram at the time of switching the monitor of the two-dimensional camera used in FIG. 4;

FIG. 6 is a schematic diagram of a single crystal pulling apparatus according to another embodiment of the present invention.

FIG. 7 is a schematic diagram of a conventional single crystal pulling apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Single crystal pulling apparatus 2 Furnace body 3 Quartz crucible 4 Graphite crucible 5 Heater 6 Motor 7 Crucible rotating shaft 8 Elevating device 9 Seed 10 Seed chuck 11 Wire 12 Wire reel rotating device 13 First camera port 14 Second camera port 15 Second 1 2D camera 16 2D camera 17 Changeover switch 18 Binarization circuit 19 Switch control circuit 20 Image processing device 21 Controller 22 Heater controller 23 Motor controller 24 Elevating device controller 25 Wire reel rotating device control circuit M Silicon melt N neck C Crown S Straight body An neck area Ac Crown growth area As Straight body area 26 Radiation shield 27 Supporting devices 27a, 27b Support member T Support

Claims (5)

[Claims] An image of a boundary between a silicon melt and a grown single crystal is taken by a two-dimensional camera, and a single crystal is pulled by a Czochralski method in which a diameter of the grown single crystal is controlled based on an image signal of the two-dimensional camera. In the apparatus, a first two-dimensional camera that focuses on the neck growth region and captures the boundary portion and outputs an image signal, and a second two-dimensional camera that focuses on the straight body growth region and captures the boundary portion and outputs an image signal A two-dimensional camera, and a shape control image signal for changing a pulling condition between the end of the neck growth of the grown single crystal and the start of the growth of the straight body part, from the image signal of the first two-dimensional camera to the image signal of the second two-dimensional camera A single crystal pulling apparatus, comprising: means for switching to a single crystal. 2. The first two-dimensional camera is mounted at a lower position than the second two-dimensional camera, and the first two-dimensional camera is connected to the second two-dimensional camera.
The single crystal pulling apparatus according to claim 1, wherein the optical axes of the two-dimensional camera are crossed. 3. The single crystal pulling apparatus according to claim 1, further comprising a radiation shield for shielding radiation heat from the surface of the silicon melt to the crystal. 4. A method according to claim 1, wherein the first two-dimensional camera captures an image of a step of growing a neck of the grown single crystal, a step of growing a bump-shaped support provided on the neck, and a step of initially growing the crown of the grown single crystal. The single crystal pulling apparatus according to claim 1. 5. The image signal is switched from the first two-dimensional camera to the second two-dimensional camera when the diameter of the bump-shaped support part and the diameter of the crown of the grown single crystal become substantially the same. The single crystal pulling apparatus according to claim 4.