JP4930488B2 - Single crystal diameter detection method, single crystal manufacturing method using the same, and single crystal manufacturing apparatus - Google Patents

Description

  The present invention relates to a method for detecting the diameter of a single crystal when a single crystal is pulled from a silicon melt contained in a crucible by the Czochralski method (CZ method), a method for producing a single crystal using the same, and The present invention relates to a single crystal manufacturing apparatus.

  In recent years, single crystals by the CZ method have been improved in quality, such as defect-free crystals, and larger in diameter of 300 mm or more. In particular, in the production of defect-free crystals, it is important to control the temperature gradient in the furnace. Further, in the crystal growth by the CZ method, it is necessary to make the crystal diameter constant.

  In the conventional single crystal diameter detection method, the single crystal diameter is detected from the change in the position of one side of the diameter. In this case, the detection value cannot be adjusted accurately unless the crystal diameter is captured from the zero point to the entire crystal radius. For this reason, in the case of a large-diameter crystal, the resolution is lowered and the detection error is large.

  In addition, this detection method has a detection error that varies between crystals when it comes into contact with the camera when cleaning the furnace after batch completion, or when the camera position changes slightly due to a shock when the chamber is disassembled. It will appear. In other words, even if the conditions are adjusted during the production of the first crystal, the diameter of the next second crystal changes, and the temperature distribution in the furnace also changes relatively, leading to poor quality of the single crystal. It was. However, since there is reproducibility if the camera position does not change, conventionally, this method was used to detect the diameter and control the crystal diameter. For this reason, the accuracy of diameter control is poor, the thermal environment in the furnace changes, and an unexpected defect may be formed in the grown single crystal, resulting in a decrease in yield due to poor quality.

  In addition, when the diameter of a single crystal is detected only on one side as in the prior art, there is variation between crystals depending on the position of the molten metal surface. That is, if the position of the molten metal surface is not at a desired position, the diameter of the grown crystal changes during the pulling, resulting in lower thickness or lower thickness. The thermal environment for the crystal length was different between the thinned crystal and the thinned crystal, leading to variations in quality. Therefore, a method for obtaining the initial molten metal surface position in order to stabilize the diameter of the crystal has been proposed (see, for example, Patent Document 1).

  However, even with this method, it is difficult to eliminate the variation in the diameter of the single crystal, and the setting diameter is set to be thick in consideration of the variation. As a result, there has been a problem of reducing the yield.

JP-A-9-235182

  The present invention provides a detection method for improving the detection accuracy of a single crystal diameter, and a diameter control with high accuracy based on the detection result. It aims at providing a manufacturing method and its manufacturing device.

  In order to solve the above problems, the present invention is a method for detecting the diameter of a single crystal when pulling up a single crystal from a silicon melt contained in a crucible by the Czochralski method, and at least the single crystal The distance between the growth point at which the diameter of the single crystal is the maximum at the growth point of the single crystal, which is the contact point between the surface and the melt surface, and the reference point at which the inner diameter of the in-furnace structure surrounding the single crystal is maximized. , Measured from outside the furnace using a camera, from the difference between the measured distance and the inner diameter of the internal structure of the furnace, to calculate the diameter of the single crystal, the value obtained by the calculation of the single crystal A method for detecting a diameter of a single crystal, characterized in that the diameter is a diameter, is provided.

  In this way, the distance between the growth point at which the diameter of the single crystal is maximum and the reference point of the in-furnace structure is measured from the outside of the furnace with a camera, and the difference between the measured distance and the inner diameter of the in-furnace structure is By calculating the diameter of the crystal and using the calculated value as the diameter of the single crystal, the detection resolution is improved compared to the case of directly detecting the diameter of the single crystal, and the diameter can be accurately determined. Can be detected. Therefore, the detection accuracy of the diameter of the large-diameter single crystal can be improved, and the yield of the single crystal can be improved and the quality variation can be reduced.

In the detection method of the present invention, the distance between the growth point at which the diameter of the single crystal is maximum and the reference point of the furnace structure is directly opposite to the growth point at which the diameter of the single crystal is maximum. It is preferable to use a camera installed as described above.
Thereby, the growth point at which the diameter of the single crystal is maximum is measured by a camera whose measurement direction is a right angle. Therefore, there is no need to approximate the single crystal diameter by calculating the single crystal diameter by using the distance between the growth point at which the measured single crystal diameter is the maximum and the reference point of the in-furnace structure. The diameter can be detected.

In the detection method of the present invention, the distance between the growth point where the diameter of the single crystal is maximum and the reference point of the in-furnace structure is measured at both ends of the growth point where the diameter of the single crystal is maximum. It is preferable to carry out using two installed cameras.
Thereby, the distance between both ends of the single crystal growth point and the reference point of the in-furnace structure can be measured using two cameras installed at both ends of the single crystal growth point. Therefore, the diameter of the single crystal can be detected more accurately by using each measured distance.

In the detection method of the present invention, the diameter (D) of the single crystal is a distance between one growth point at both ends of the growth point where the diameter of the single crystal is maximum and a reference point of the in-furnace structure ( a), the distance (b) between the other growth point and the reference point of the in-furnace structure, and the inner diameter (c) of the in-furnace structure can be calculated by the following formula (1) (claims) Item 4).
D = c- (a + b) (1)
By calculating the diameter of the single crystal by such an expression (1), the diameter of the single crystal can be detected indirectly and easily. Moreover, the diameter of a single crystal can be detected with higher accuracy by calculating the diameter of the single crystal according to Equation (1) using the distance measured by two cameras.

Furthermore, in the detection method of the present invention, the diameter (D) of the single crystal is the distance between one growth point at both ends of the growth point where the diameter of the single crystal is maximum and the reference point of the in-furnace structure ( a) The inner diameter (c) of the in-furnace structure can be used to calculate the following equation (2).
D = c-2a (2)
By calculating the diameter of the single crystal according to such an expression (2), using the distance between the growth point at which the diameter of the single crystal is measured with one camera and the reference point of the in-furnace structure, The diameter of the single crystal can be detected indirectly and easily.

In addition, when the cone portion of the single crystal is formed, the diameter of the single crystal is measured using one camera for detecting the cone portion diameter, and when the straight body portion of the single crystal is formed, the diameter of the straight barrel is detected. The diameter of the single crystal can be measured using one or two cameras.
In this way, by measuring the diameter of the single crystal using different cameras when forming the cone portion and the straight body portion of the single crystal, it is possible to improve the resolution of detecting the diameter when forming the straight body portion. . Even when measurement is performed using a camera with a narrow measurement field of view, the diameter of a single crystal having a large diameter can be reliably detected with high accuracy.

In addition, the diameter of the single crystal is detected by at least one of the methods described above, and the single crystal is pulled up and manufactured based on the detection result while controlling the diameter of the single crystal. A method for producing a single crystal is provided (claim 7).
As described above, according to the single crystal diameter detection method of the present invention, the diameter of a large-diameter single crystal can be detected with high accuracy. In the present invention, since the diameter of the single crystal can be controlled with high accuracy based on the detection result, for example, the defect-free crystal can be grown industrially stably with a high yield. The high quality silicon single crystal can be efficiently manufactured with high productivity.

  Furthermore, the present invention is a single crystal manufacturing apparatus for manufacturing a silicon single crystal by pulling up a single crystal from a silicon melt stored in a crucible by the Czochralski method, and at least the crucible for storing the silicon melt A furnace internal structure surrounding the single crystal, a growth point at which the diameter of the single crystal is a maximum at a single crystal growth point that is a contact point between the single crystal and the melt surface, and an inner diameter of the furnace internal structure. A growth point where the diameter of the single crystal measured by the camera is a maximum, and a diameter control device for controlling the diameter of the single crystal, and From the difference between the distance from the reference point of the in-furnace structure and the inner diameter of the in-furnace structure, it is detected by calculating the diameter of the single crystal, and based on the detection result, the diameter control device Control the diameter of a single crystal Providing a single crystal manufacturing apparatus characterized by the at is (claim 8).

  Thus, the single crystal manufacturing apparatus of the present invention measures the distance between the growth point at which the diameter of the single crystal is maximum and the reference point of the in-furnace structure with the camera from the outside of the furnace, and the measured distance and the in-furnace structure Detection is performed by calculating the diameter of the single crystal from the difference from the inner diameter of the object, and the diameter of the single crystal is controlled based on the detection result. Therefore, compared with the case of directly detecting the diameter of the single crystal, the detection resolution is improved and the diameter can be detected with high accuracy. In addition, the detection accuracy of the large diameter can be improved, and a device capable of improving the yield of single crystals and reducing quality variations can be obtained.

In the manufacturing apparatus of the present invention, it is preferable that the camera is installed so as to face a growth point where the diameter of the single crystal is maximum (claim 9).
Thus, the camera is positioned at a right angle to the growth point where the diameter of the single crystal is maximum. Therefore, there is no need to approximate the single crystal diameter by calculating the single crystal diameter by using the distance between the growth point at which the measured single crystal diameter is the maximum and the reference point of the in-furnace structure. It can be set as the apparatus which can detect a diameter.

In the manufacturing apparatus of the present invention, it is preferable that two cameras are installed at both ends of the growth point where the diameter of the single crystal is maximum (claim 10).
Thereby, the distance between both ends of the single crystal growth point and the reference point of the in-furnace structure can be measured using two cameras installed at both ends of the single crystal growth point. Therefore, it can be set as the apparatus which can detect the diameter of a single crystal more correctly by using each measured distance.

In the manufacturing apparatus of the present invention, the diameter (D) of the single crystal is the distance between one growth point at both ends of the growth point where the diameter of the single crystal is maximum and the reference point of the in-furnace structure ( a), the distance (b) between the other growth point and the reference point of the in-furnace structure, and the inner diameter (c) of the in-furnace structure may be calculated by the following formula (1). Preferred (claim 11).
D = c- (a + b) (1)
By calculating the diameter of the single crystal by such an equation (1), the apparatus can detect the diameter of the single crystal indirectly and easily. Further, by calculating the diameter of the single crystal according to the equation (1) using the distance measured by the two cameras, the apparatus can detect the diameter of the single crystal with higher accuracy.

In the manufacturing apparatus of the present invention, the diameter (D) of the single crystal is the distance between one growth point at both ends of the growth point where the diameter of the single crystal is maximum and the reference point of the in-furnace structure ( a) It can be calculated by the following formula (2) using the inner diameter (c) of the in-furnace structure (claim 12).
D = c-2a (2)
By calculating the diameter of the single crystal according to such an expression (2), using the distance between the growth point at which the diameter of the single crystal is measured with one camera and the reference point of the in-furnace structure, The apparatus can detect the diameter of the single crystal indirectly and easily.

Further, in the manufacturing apparatus of the present invention, one or two cameras are installed for detecting the diameter of the straight body when forming the straight body of the single crystal. In addition to the camera, the single crystal It is preferable that one camera is installed for detecting the diameter of the cone portion when forming the cone portion.
In this way, the single-crystal cone diameter detection and straight cylinder diameter detection cameras are installed according to applications, so that the diameter detection resolution at the time of straight cylinder formation can be improved, and the large aperture It can be set as the apparatus which can detect the diameter of this single crystal with high precision. In addition, it is possible to install a camera with a narrower measurement field of view than when measuring the diameter of a single crystal with a single camera regardless of the application.

  As described above, according to the method for detecting a single crystal diameter of the present invention, the diameter of a large-diameter single crystal can be detected with high accuracy. And based on this detection result, it is possible to control the diameter of a single crystal with high precision. Therefore, for example, defect-free crystals can be grown with good yield and industrially stably, and a desired high-quality silicon single crystal can be efficiently produced with high productivity.

Hereinafter, the present invention will be described more specifically.
As described above, conventionally, the single crystal diameter was detected from the change in the position of one side of the single crystal diameter, but with this method, the single crystal diameter must be captured from the zero point to the entire crystal radius. Since the detection value cannot be accurately adjusted, there is a problem that the resolution is lowered and the detection error is large in the case of a single crystal having a large diameter.

  Therefore, the present inventors can improve the detection resolution if the single crystal diameter can be detected by measuring a narrower range rather than capturing all of the radius from the zero point of the single crystal diameter. The distance between the growth point where the diameter of the single crystal is maximum and the reference point where the inner diameter of the furnace structure is maximum is measured with a camera, and the measured distance and the known inner diameter of the furnace structure are measured. From this difference, an attempt was made to calculate the diameter of the single crystal.

As a result, it was found that the calculated diameter of the single crystal coincided with the actual diameter of the single crystal.
And when two cameras are used, the diameter (D) of the single crystal is the distance (a) between one growth point at both ends of the growth point where the diameter of the single crystal is maximum and the reference point of the in-furnace structure. It was also found that the distance (b) between the other growth point and the reference point of the in-furnace structure and the inner diameter (c) of the in-furnace structure can be calculated by the following formula (1).
D = c- (a + b) (1)

Further, even if there is one camera, the diameter (D) of the single crystal is the distance between one growth point at both ends of the growth point where the diameter of the single crystal is maximum and the reference point of the in-furnace structure. It was also found that (a) can be calculated by the following formula (2) using the inner diameter (c) of the in-furnace structure.
D = c-2a (2)

The present invention has been completed based on the above findings, and the present invention will be described in more detail below with reference to the drawings. However, the present invention is not limited to these.
FIG. 1 is a schematic view showing an example of a single crystal production apparatus of the present invention.

  The single crystal manufacturing apparatus 20 includes a hollow cylindrical chamber 1, and a crucible 5 is disposed at the center thereof. This crucible has a double structure, and is an inner holding container made of quartz having a bottomed cylindrical shape (hereinafter simply referred to as “quartz crucible 5a”) and a similarly bottomed fitting adapted to hold the outside of the quartz crucible 5a. It is composed of a cylindrical graphite outer holding container (“graphite crucible 5b”).

  These crucibles 5 are fixed to the upper end of the support shaft 6 so as to be able to rotate and move up and down, and a resistance heating heater 8 is arranged substantially concentrically outside the crucible. Further, a heat insulating material 9 is concentrically arranged around the outside of the heater 8. And the silicon melt 2 which melt | dissolved the silicon raw material with the heater 8 is accommodated in the crucible.

  The central axis of the crucible 5 filled with the silicon melt 2 is a pull-up wire (or pull-up shaft that rotates at a predetermined speed in the reverse direction or the same direction on the same axis as the support shaft 6. And a seed crystal 4 is held at the lower end of the pulling shaft 7. A silicon single crystal 3 is formed on the lower end surface of the seed crystal 4.

  Furthermore, the single crystal manufacturing apparatus 20 determines the distance between the in-furnace structure 10 surrounding the silicon single crystal 3 and the growth point of the single crystal, which is a contact point between the single crystal 3 and the melt surface, and the in-furnace structure 10. A camera 11 for measuring from outside the furnace and a diameter control device 12 for controlling the diameter of the single crystal 3 are provided.

  The diameter control device 12 outputs signals to the support shaft 6 and the pulling shaft 7 or the heater 8 according to the detection result of the diameter of the single crystal using the camera 11, and the crucible position, the crucible rising speed, the seed crystal. The diameter of the single crystal is controlled by controlling the position, pulling speed, heater power, etc.

  The single crystal manufacturing apparatus 20 measures the distance between the growth point at which the diameter of the single crystal 3 is maximum and the reference point at which the inner diameter of the in-furnace structure 10 is maximum with the camera 11 from the outside of the furnace, and the measured distance and the furnace Detection is performed by calculating the diameter of the single crystal 3 from the difference in inner diameter of the internal structure 10, and the diameter of the single crystal 3 is controlled by the diameter control device 12 based on the detection result. Therefore, compared with the case of directly detecting the diameter of the single crystal, the detection resolution is improved and the diameter can be detected with high accuracy. Therefore, the detection accuracy of a large diameter can be improved, and a device capable of improving the yield of single crystals and reducing quality variations can be obtained.

In this case, it is preferable that the manufacturing apparatus is a camera installed so as to face the growth point where the diameter of the single crystal is maximum.
Here, FIG. 2 is a diagram schematically showing a top surface configuration example of the single crystal and the camera in the present invention. As shown in FIG. 2, the growth point at which the diameter of the single crystal is maximum is located at a right angle from the photographing direction of the camera. Therefore, there is no need to approximate the single crystal diameter by calculating the single crystal diameter by using the distance between the growth point at which the measured single crystal diameter is the maximum and the reference point of the in-furnace structure. Can detect the diameter

In the manufacturing apparatus, as shown in FIG. 2, two cameras can be installed at both ends of the growth point where the diameter of the single crystal is maximum.
Of the distances measured by the two cameras, the distance (a) between one growth point and the reference point of the in-furnace structure at both ends of the growth point where the diameter of the single crystal is maximum, and the other growth point As the distance (b) from the reference point of the in-furnace structure, the inner diameter (c) of the in-furnace structure can be used to calculate the diameter (D) of the single crystal by the following formula (1). Since the inner diameter (c) of the in-furnace structure is the inner diameter of the used in-furnace structure, it can be known in advance.
D = c- (a + b) (1)

  By calculating the diameter of the single crystal by such an expression (1), the diameter of the single crystal can be detected indirectly and easily. Further, by calculating the diameter of the single crystal according to the equation (1) using the distance measured by the two cameras, the apparatus can detect the diameter of the single crystal with higher accuracy.

Furthermore, in the manufacturing apparatus, one camera can be used.
In this case, the diameter (D) of the single crystal is the distance (a) between one growth point at both ends of the growth point where the diameter of the single crystal is maximum and the reference point of the in-furnace structure, and the inner diameter of the in-furnace structure. Using (c), it can be calculated by the following equation (2).
D = c-2a (2)

  By calculating the diameter of the single crystal according to the equation (2), the diameter of the single crystal can be detected indirectly and easily without using two cameras.

Further, in the above manufacturing apparatus, one or two cameras are installed as described above for detecting the diameter of the straight body when forming the straight body portion of the single crystal, and in addition to this, when forming the cone portion of the single crystal. It is also possible to install one camera for detecting the cone diameter.
In this way, by installing cameras for different applications for detecting the cone diameter of a single crystal and for detecting the diameter of a straight cylinder, it is possible to improve the resolution of detecting the diameter when forming the straight cylinder, It can be set as the apparatus which can detect the diameter of a single crystal accurately. In addition, it is possible to install a camera with a narrower measurement field of view than when measuring the diameter of a single crystal with a single camera regardless of the application.

  In the present invention, for example, when the silicon single crystal is pulled from the melt in the crucible by the CZ (Czochralski) method using such a single crystal manufacturing apparatus, the diameter of the single crystal is set as follows. To detect.

  First, the distance between the growth point at which the diameter of the single crystal is maximum and the reference point at which the inner diameter of the in-furnace structure is maximized is measured from outside the furnace using a camera. Here, FIG. 3 is a diagram showing the measurement range of the camera of the single crystal manufacturing apparatus of the present invention. The distances a and b in FIG. 3 are distances measured using a camera. Then, the diameter of the single crystal is calculated from the difference between the measured distance and the inner diameter of the in-furnace structure. Thereby, the obtained value can be indirectly detected as the diameter of the single crystal.

Further, the measurement of the distance between the growth point at which the diameter of the single crystal is maximum and the reference point of the in-furnace structure is as shown in FIG. 2 so as to face the position of the growth point at which the diameter of the single crystal is maximum. It is preferable to use a camera installed in
Thereby, the growth point at which the diameter of the single crystal is maximum is measured by a camera whose measurement direction is a right angle. Therefore, there is no need to approximate the single crystal diameter by calculating the single crystal diameter by using the distance between the growth point at which the measured single crystal diameter is the maximum and the reference point of the in-furnace structure. The diameter can be detected.

  Furthermore, it can also measure using two cameras installed in the both ends of the growth point where the diameter of a single crystal becomes the maximum. Specifically, as shown in FIG. 2, measurement is performed using two cameras placed so as to face the positions of both ends of the growth point where the diameter of the single crystal is maximum, and these two cameras are used. The diameter of the single crystal is calculated using the measured distances a and b.

2 and 3, the distance between one growth point at both ends of the growth point at which the diameter of the single crystal is maximum and the reference point of the in-furnace structure is (a), and the other growth point. And the reference point of the in-furnace structure, the diameter (D) of the single crystal can be calculated by the following formula (1) using the inner diameter (c) of the in-furnace structure.
D = c- (a + b) (1)

  By calculating the diameter of the single crystal by such an expression (1), the diameter of the single crystal can be detected indirectly and easily. Moreover, the diameter of a single crystal can be detected with higher accuracy by calculating the diameter of the single crystal according to Equation (1) using the distance measured by two cameras.

Further, the distance between the growth point at which the diameter of the single crystal is maximum and the reference point of the in-furnace structure can be measured with a single camera.
In this case, the diameter (D) of the single crystal is the distance (a) between one growth point at both ends of the growth point where the diameter of the single crystal is maximum and the reference point of the in-furnace structure, and the inner diameter of the in-furnace structure. Using (c), it can be calculated by the following equation (2).
D = c-2a (2)

  By calculating the diameter of the single crystal according to the equation (2), the diameter of the single crystal can be detected indirectly and easily without using two cameras.

In addition, when forming a single crystal cone part, the diameter of the single crystal is measured using one camera for detecting the cone part diameter. When forming a single crystal straight body part, one unit for detecting the straight cylinder diameter is used. Alternatively, the diameter of a single crystal can be measured using two cameras.
In this way, by measuring the diameter of the single crystal using different cameras when forming the cone portion and the straight body portion of the single crystal, it is possible to improve the resolution of detecting the diameter when forming the straight body portion. . Even when measurement is performed using a camera having a narrow measurement field of view, the diameter of a single crystal having a large diameter can be detected with high accuracy.

  And by detecting the diameter of a single crystal in this way, the diameter of a large-diameter single crystal can be detected with high accuracy. Based on this detection result, the single crystal is pulled up while controlling the diameter of the single crystal, for example, to grow a defect-free crystal that requires high-precision diameter control with high yield and industrial stability. The desired high quality silicon single crystal can be efficiently manufactured with high productivity.

Next, the present invention will be described more specifically with reference to Examples and Comparative Examples of the present invention, but the present invention is not limited to these.
(Example)
A silicon raw material was filled in a crucible using a single crystal manufacturing apparatus as shown in FIG. 1, and the silicon raw material was melted with a heater to obtain a silicon melt. Then, as shown in FIG. 2, the single crystal diameter was detected using two cameras, and the silicon single crystal having a diameter of 300 mm was pulled up and manufactured based on the detection result while controlling the single crystal diameter. Thereafter, the diameter of the produced single crystal was measured outside the furnace. FIG. 4 shows the actual diameter of the single crystal and the detection result.

From FIG. 4, the detection result of the single crystal diameter at the time of pulling the single crystal was almost the same as the actual single crystal diameter, and the error was 0.5 mmφ at the maximum.
Moreover, when the defect of the obtained silicon single crystal was measured, a desired defect-free crystal was obtained, and a high-quality silicon single crystal could be efficiently produced with high productivity.

  Moreover, about the position change of the hot_water | molten_metal surface at this time, a schematic diagram is shown in FIG. When the molten metal surface changes, even when the single crystal diameter does not change, the growth point of the single crystal moves in the vertical direction as shown in FIG. However, it can be seen that the lateral direction, that is, the distance between the growth point and the in-furnace structure does not change. In this way, by setting the camera so as to face the position of the growth point where the diameter of the single crystal is maximum, the change in the lateral direction reflects only the change in the actual diameter of the single crystal. From this, it can be seen that in the present invention, the position change of the molten metal surface does not affect the detection of the single crystal diameter.

  In addition, since the two ends of the single crystal growth point were measured using two cameras, even if the pulling wire was shaken, the detection on the opposite side was reduced when the detection on one side was increased, and the measurement error due to wire shake was canceled. It is considered that it does not affect the detection of the single crystal diameter.

  Moreover, the measurement visual field of the camera used for the detection of the single crystal diameter at this time was 100 mm. Table 1 shows the relationship between the measurement field length of the camera, the detection diameter of the camera, and the detection value (bit) of the camera.

  From Table 1, when the measurement visual field length of the camera is 0 mm, the detected diameter of the camera is 250 mmφ, and the detected value of the camera is 0 bit. Further, since the reference point of the in-furnace structure is placed in the measurement field of the camera, the measurement field length of the camera is 100 mm, the maximum detection diameter of the camera at this time is 450 mmφ, and the detection value of the camera is 4000 bits. Therefore, the detection resolution of the single crystal diameter in this case is 200 mmφ / 4000 bit = 0.05 mmφ / bit from the difference of the single crystal diameter of 200 mmφ (= 450 mmφ−250 mmφ) and the detected value of 4000 bits (= 4000 bit−0 bit). .

(Comparative example)
Using a conventional single crystal manufacturing apparatus, a silicon raw material was filled into a crucible, and the silicon raw material was melted with a heater to obtain a silicon melt. Unlike the example, the single crystal diameter is detected from the position change of the crystal growth point using one camera, and the single crystal diameter is controlled based on the detection result. Was manufactured. Thereafter, the diameter of the produced single crystal was measured outside the furnace. FIG. 6 shows the actual diameter and detection result of the single crystal. FIG. 7 is a diagram schematically showing an example of the upper surface configuration of the single crystal and the camera.

From FIG. 6, the detection result of the single crystal diameter is a substantially constant detection diameter, but the actual diameter is underweight as the pulling progresses, and the maximum error is 3.0 mmφ.
This is considered to be caused by a measurement error due to a change in the molten metal surface position.
Moreover, when the defect measurement of the obtained silicon single crystal was carried out, a desired defect-free crystal could hardly be obtained.

  Here, about the position change of the hot_water | molten_metal surface at this time, a schematic diagram is shown in FIG. Moreover, FIG. 9 is a figure which shows the measurement range of the camera of a single crystal manufacturing apparatus. As shown in FIG. 8, when the installation angle of the camera is 45 degrees, the diameter of the single crystal changes by 2 mmφ when the molten metal surface changes by 1 mm. That is, when the molten metal surface is lowered by 1 mm, the actual diameter of the single crystal is controlled to be 2 mmφ thin. This is presumably because the camera measures only one side of the single crystal as shown in FIG. 9, and the detected value of the single crystal diameter is affected by the position change of the molten metal surface.

  Furthermore, since only one side of the single crystal was measured using a single camera, if the pulling wire swings during the pulling of the single crystal and the position of the molten metal surface changes, the change in position directly affects the detection of the single crystal diameter. It is thought that an error occurred.

  At this time, the measurement visual field of the camera used for the detection of the single crystal diameter was 200 mm as shown in FIG. Table 2 shows the relationship between the measurement field length of the camera, the detection diameter of the camera, and the detection value (bit) of the camera.

  From Table 2, when the measurement visual field length of the camera is 0 mm, the detected diameter of the camera is 0 mmφ, and the detected value of the camera is 0 bit. When the measurement field length of the camera is 200 mm, the detection diameter of the camera is 400 mmφ, and the detection value of the camera is 4000 bits. Therefore, the detection resolution of the single crystal diameter in this case is 400 mmφ / 4000 bit = 0.1 mmφ / bit from the difference of the single crystal diameter of 400 mmφ (= 400 mmφ−0 mmφ) and the detected value of 4000 bits (= 4000 bit−0 bit). .

  As described above, in the examples, the single crystal diameter can be stably detected with an error within a range of a maximum of 0.5 mmφ from the start to the end of the straight body of the single crystal, and a desired defect-free crystal can be obtained. However, in the comparative example, it can be seen that the detection error of the single crystal diameter is as large as 3.0 mmφ at the maximum, and a desired defect-free crystal cannot be obtained. In addition, it can be seen that the detection resolution of the example is 0.05 mmφ / bit, which is higher than the comparative example of 0.1 mmφ / bit.

  Thus, according to the method for detecting a single crystal diameter of the present invention, the diameter of a single crystal having a large diameter can be detected with high accuracy. According to the single crystal manufacturing method and single crystal manufacturing apparatus of the present invention, the diameter of the single crystal is accurately detected, and the single crystal is pulled up while controlling the diameter of the single crystal based on the detection result. Therefore, it is possible to control the diameter of the single crystal with high accuracy. For example, it is possible to grow a defect-free crystal stably with good yield and industrially, and efficiently produce a desired high-quality silicon single crystal. Can be manufactured with high productivity.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

It is the schematic which shows an example of the single crystal manufacturing apparatus of this invention. It is a figure which shows typically the example of an upper surface structure of the single crystal and camera in this invention. It is a figure which shows the measurement range of the camera of the single crystal manufacturing apparatus of this invention. It is a figure which shows the actual diameter and detection result of the single crystal in an Example. It is the schematic shown about the position change of the hot_water | molten_metal surface in an Example. It is a figure which shows the actual diameter and detection result of the single crystal in a comparative example. It is a figure which shows typically the upper surface structural example of the single crystal and camera in a comparative example. It is the schematic shown about the influence of the position change of the hot_water | molten_metal surface in a comparative example. It is a figure which shows the measurement range of the camera of the single crystal manufacturing apparatus of a comparative example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Chamber, 2 ... Silicon melt, 3 ... Silicon single crystal, 4 ... Seed crystal, 5 ... Crucible, 5a ... Quartz crucible, 5b ... Graphite crucible, 6 ... Supporting shaft, 7 ... Pulling up shaft, 8 ... Heater, DESCRIPTION OF SYMBOLS 9 ... Thermal insulation material 10 ... Furnace structure, 11 ... Camera, 12 ... Diameter control apparatus, 20 ... Single crystal manufacturing apparatus.

Claims (13)

  A method for detecting the diameter of a single crystal when pulling up the single crystal from a silicon melt contained in a crucible by the Czochralski method, wherein the single crystal is at least a contact point between the single crystal and the melt surface. The distance between the growth point at which the diameter of the single crystal is maximum at the growth point and the reference point at which the inner diameter of the in-furnace structure surrounding the single crystal is maximum is measured from outside the furnace using a camera, From the difference between the measured distance and the inner diameter of the furnace structure, the diameter of the single crystal is calculated, and the value obtained by calculating the single crystal diameter is the single crystal diameter. Detection method.   The distance between the growth point at which the diameter of the single crystal is maximum and the reference point of the in-furnace structure is measured using a camera installed so as to face the growth point at which the diameter of the single crystal is maximum. The method for detecting a single crystal diameter according to claim 1.   The distance between the growth point where the diameter of the single crystal is maximum and the reference point of the in-furnace structure is measured using two cameras installed at both ends of the growth point where the diameter of the single crystal is maximum. The method for detecting a single crystal diameter according to claim 1 or 2, wherein the method is performed. The diameter (D) of the single crystal is the distance (a) between one growth point at both ends of the growth point where the diameter of the single crystal is maximum and the reference point of the in-furnace structure, and the other growth point and the 4. The calculation according to claim 1, wherein the distance (b) from the reference point of the furnace internal structure and the inner diameter (c) of the furnace internal structure are used to calculate according to the following formula (1): The method for detecting a single crystal diameter according to claim 1.
D = c- (a + b) (1) The diameter (D) of the single crystal is the distance (a) between one growth point at both ends of the growth point at which the diameter of the single crystal is maximum and the reference point of the in-furnace structure, The method for detecting a single crystal diameter according to claim 1 or 2, wherein the inner diameter (c) is used to calculate the single crystal diameter according to the following formula (2).
D = c-2a (2)   When forming the cone portion of the single crystal, the diameter of the single crystal is measured using one camera for detecting the cone portion diameter. When forming the straight body portion of the single crystal, 1 for detecting the diameter of the straight cylinder is used. 6. The method for detecting a single crystal diameter according to claim 1, wherein the diameter of the single crystal is measured using a stand or two cameras.   The diameter of the single crystal is detected by at least the method according to any one of claims 1 to 6, and the single crystal is pulled up while controlling the diameter of the single crystal based on the detection result. A method for producing a single crystal, comprising:   A single crystal manufacturing apparatus for manufacturing a silicon single crystal by pulling up a single crystal from a silicon melt stored in a crucible by the Czochralski method, wherein at least the crucible for storing the silicon melt and the single crystal The surrounding furnace structure, the growth point at which the diameter of the single crystal is the largest at the growth point of the single crystal that is the contact point between the single crystal and the melt surface, and the reference point at which the inner diameter of the furnace structure is maximized And a diameter control device for controlling the diameter of the single crystal, the growth point at which the diameter of the single crystal measured by the camera is maximized, and the structure in the furnace Detection is performed by calculating the diameter of the single crystal from the difference between the distance from the reference point and the inner diameter of the internal structure of the furnace, and the diameter control device controls the diameter of the single crystal based on the detection result. Special features And the single crystal manufacturing apparatus.   The single crystal manufacturing apparatus according to claim 8, wherein the camera is installed so as to face a growth point where the diameter of the single crystal is maximum.   10. The single crystal manufacturing apparatus according to claim 8, wherein two cameras are installed at both ends of a growth point where the diameter of the single crystal is maximum. The diameter (D) of the single crystal is the distance (a) between one growth point at both ends of the growth point where the diameter of the single crystal is maximum and the reference point of the in-furnace structure, and the other growth point and the The distance from the reference point of the furnace internal structure (b) and the inner diameter (c) of the furnace internal structure are used to calculate by the following formula (1). The single crystal manufacturing apparatus according to any one of 10.
D = c- (a + b) (1) The diameter (D) of the single crystal is the distance (a) between one growth point at both ends of the growth point at which the diameter of the single crystal is maximum and the reference point of the in-furnace structure, The single-crystal manufacturing apparatus according to claim 8 or 9, wherein the single-crystal manufacturing apparatus is calculated by the following formula (2) using the inner diameter (c).
D = c-2a (2)   One or two cameras are installed for detecting the diameter of the straight body when the straight body of the single crystal is formed. In addition to the camera, the diameter of the cone when the cone of the single crystal is formed The single crystal manufacturing apparatus according to any one of claims 8 to 12, wherein one camera is installed for detection.

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