TWI675131B - Method and device for manufacturing single crystal - Google Patents

Abstract

[Question] Reduce the diameter measurement error when changing the position of the diameter measuring line in accordance with the change in the position of the liquid surface. [Solution] A method for manufacturing a single crystal based on the Chuklasky method of pulling a single crystal from a melt in a crucible, including the steps of photographing a junction between a pre-recorded single crystal and a pre-recorded melt; In the image, at least one diameter measurement line L ₁ in the horizontal direction and the two intersection points P ₁ , P ₁ ′ of the fusion ring 4 appearing at the junction of the previous note and the central position C _{0 of} the fusion ring 4 are obtained. The step of changing the diameter; the step of changing the vertical position of the diameter measurement line L ₁ in the pre-recorded image in accordance with the change of the liquid level position of the melt; based on the positions before and after the position change of the diameter measurement line L ₁ A step of correcting the first and second diameter measurement values of the pre-single-crystal, and correcting the pre-second diameter measurement values of the pre-single-crystal.

Description

Method and device for manufacturing single crystal

The present invention relates to a method and an apparatus for producing a single crystal, and more particularly to a method for measuring a crystal diameter performed in a pulling process of a single crystal by the Chuklaski method (CZ method).

Silicon single crystals, which are substrate materials for semiconductor devices, are mostly manufactured by the CZ method. In the CZ method, a seed crystal is immersed in a silicon melt contained in a quartz crucible, and the seed crystal is slowly raised while the seed crystal and the crucible are rotated, thereby growing a large-diameter single crystal at the lower end of the seed crystal.

Regarding the CZ method, for example, Patent Document 1 describes a method in which a single crystal is pulled while controlling a position of a crucible so that a liquid surface position of a silicon melt relative to a structure in a furnace such as a heater is always maintained at Certain location. In this method, the measured value of the liquid surface position and the correction value of the ascending speed of the crucible are calculated. In order to maintain the liquid surface position constant, the correction value is added to the necessary quantitative value of the ascending speed of the crucible, and the corrected ascent is used. Speed control liquid level position. In this method, the crystal diameter is measured from the output of the one-dimensional CCD camera, and the liquid surface position is calculated from the mirror image of the reference reflector reflected on the molten liquid surface.

In addition, Patent Document 2 describes a first crystal diameter measured from a melting ring at a junction between a silicon melt and a silicon single crystal photographed with a CCD camera, and two ends of the crystal diameter facing the silicon single crystal, which are arranged in parallel, are used. The second crystal diameter measured by the two CCD cameras was used to calculate the height position of the silicon melt surface in the crucible during the silicon single crystal pulling from the difference between the first crystal diameter and the second crystal diameter.

In addition, Patent Document 3 describes a method for capturing a melting ring appearing at the interface between a single crystal and a melt surface with a camera, and setting a horizontal row in a photographed image orthogonal to the pulling axis direction of the single crystal. It is a diameter measurement line, and the diameter of a single crystal is calculated | required from the position of two intersections of a fusion ring and an intersecting diameter measurement line.

In the conventional method described in Patent Document 1, which always maintains the liquid surface position constant during pulling of a single crystal, it is difficult to make the in-plane distribution of crystal defects from the upper end (top) to the lower end (bottom) of the single crystal to be Certainly, there is a limit to the improvement of the manufacturing yield of high-quality silicon single crystals. Therefore, a control method for changing the position of the liquid surface during the pulling of the single crystal is being investigated. According to this control method, the stabilization can be achieved even in a place where it is difficult to achieve stabilization of the crystallization thermal history, and the in-plane distribution of crystal defects from the top to the bottom of the single crystal can be made constant.

When the position of the liquid surface is changed in the pulling process of the single crystal, the position of the melting ring in the image captured by the camera also changes. Therefore, when the diameter measurement line is fixed to a specific pixel row in a captured image, the position of the intersection point with the melting ring changes, and a diameter measurement error of a single crystal easily occurs. Therefore, a method of changing the position in the vertical direction of the diameter measuring line in accordance with the change in the position of the liquid surface is adopted. The position of the diameter measurement line in the captured image is changed in accordance with the change in the position of the liquid surface, whereby the diameter measurement line can follow the molten ring, and the diameter measurement error of the single crystal can be reduced.

Prior technical documents Patent document: Patent document 1: Japanese Patent Laid-Open No. 2001-342095 Patent document 2: Japanese Patent Laid-Open No. 2013-170097 Patent document 3: Japanese Patent Laid-Open No. 2017-154901

[Problems to be Solved by Invention]

However, when the position of the diameter measurement line in the captured image is changed in accordance with the change in the position of the liquid surface, there is a problem that the diameter measurement value changes greatly due to the change in the position of the diameter measurement line. The single crystal pulling process is based on the measurement result of the crystal diameter to control the crystal pulling speed. If the crystal pulling speed cannot be strictly controlled to stabilize the thermal history of the crystal, the production yield of high-quality single crystal cannot be improved. It is urgent to correctly measure the crystal diameter and control it.

Therefore, an object of the present invention is to provide a method and an apparatus for manufacturing a single crystal, which can reduce the variation of the diameter measurement value even if the position of the diameter measurement line in the captured image is changed in accordance with the change of the liquid surface position. [Means to solve the problem]

The present invention is devoted to exploring the reason why the diameter measurement value changes greatly when the position of the diameter measurement line in the captured image is changed in accordance with the change in the position of the liquid surface. As a result, it is found that the time point and diameter measurement of the diameter measurement value change The point in time at which the position of the line changes is the same. By correcting the diameter measurement value obtained at this time point, the variation in the diameter measurement value can be reduced.

The present invention is based on this technical insight. The method for manufacturing a single crystal according to the present invention is a method for manufacturing a single crystal based on the Chuklasky method of pulling a single crystal from a melt in a crucible, which is characterized by: Steps at the junction of the pre-single crystal and the pre-smelt; from the position of at least one diameter measurement line in the horizontal direction set in the captured image and the position of the two intersections of the fusion ring appearing at the pre-junction and the pre-fusion ring The step of finding the diameter of the previous single crystal in the center position of the step; the step of changing the vertical position of the previous diameter measuring line in the previous captured image in accordance with the change of the liquid level position of the previous melt; based on the position of the previous diameter measuring line A step of correcting the first and second diameter measurement values of the pre-single crystal obtained by the positions before and after the change, respectively, and correcting the pre-second diameter measurement of the pre-single crystal.

According to the present invention, it is possible to suppress a change in a diameter measurement value generated when a position in a vertical direction of a diameter measurement line in a captured image is changed in accordance with a change in the position of the liquid surface. Therefore, the stability of the obtained crystal diameter can be improved, and the manufacturing yield of high-quality single crystal can be improved.

In the present invention, this is preferable: the step of correcting the second measured diameter of the previous diameter includes: a step of calculating a ratio of the second measured diameter of the previous diameter to the first measured diameter of the previous diameter as a correction factor; and multiplying the previous correction factor by a factor; The procedure for measuring the second diameter is described above. This makes it possible to correct the measured value of the crystal diameter by a simple calculation.

In the present invention, it is better to: The step of obtaining the diameter of the previous single crystal is to simultaneously calculate the measured value of the multiple diameter of the previous single crystal by using a plurality of diameter measurement lines set in the previously recorded image; moving the previous diameter measurement line The step of positioning in the vertical direction is to move the diameter measuring line of the preceding plural number in parallel in the vertical direction. This can improve the reliability of the diameter measurement value.

In the present invention, this is preferable: the first diameter measurement value is a value obtained from the diameter measurement line before the position of the previous diameter measurement line is changed; the second diameter measurement value is a previous diameter measurement line. The value obtained from the diameter measurement line after the position of. Thereby, calculation and correction of a crystal diameter can be performed with one diameter measurement line.

In the present invention, it is preferable that: the preamble captured image includes first to third pixel rows that are continuous in the vertical direction; the preamble plural diameter measurement line includes a first diameter measurement line set in the first pixel row of the preamble, And the second diameter measurement line set on the second pixel row of the previous pixel adjacent to the first pixel row of the first note; and in the step of changing the vertical position of the first diameter measurement line, the first and second diameter measurement lines of the first Move to the 2nd pixel row of the preamble and the 3rd pixel row of the predecessor adjacent to the 2nd pixel row of the predecessor; the 1st diameter measurement value of the predecessor is the first diameter measurement line after the position change The value obtained; the second diameter measurement value in the previous description is the value obtained from the second diameter measurement line in the previous description after the position of the plural diameter measurement line in the previous description is changed. This makes it possible to accurately calculate the correction amount of the crystal diameter using the two diameter measurement values obtained at the same time.

A method for manufacturing a single crystal according to the present invention includes a variable variable control step for gradually increasing or reducing a gap between a thermal shield disposed above the previous melt and a previous melt, and changing the vertical of the previous diameter measurement line. The step of the direction position is preferably changed in accordance with the change in the position of the preface liquid level caused by the preface gap variable control step to change the vertical position of the preface diameter measurement line in the preface captured image. In this case, the method for manufacturing a single crystal according to the present invention may further include a gap fixing control step of controlling the gap described above to be fixed. Thereby, it is possible to stably pull from the top to the bottom of the single crystal, and it is possible to improve the manufacturing yield of the high-quality single crystal.

In addition, the single crystal manufacturing apparatus according to the present invention is characterized in that it includes: a crucible supporting the melt; a heater for heating the previously mentioned melt; a pulling shaft for pulling the single crystal from the previously mentioned melt; and a crucible for driving the former crucible up and down Lifting mechanism; crystal pulling mechanism that pulls a single crystal from the previous melt in the previous crucible; a camera that captures the junction of the previous crystal and the previous melt; an image processing unit that processes the images taken by the previous camera; control The control unit of the pre-heater, pre-roller shaft, and pre-crucible lifting mechanism; the pre-image processing unit sets at least one diameter measurement line in the horizontal direction in the captured image and the melting ring appearing at the boundary of the pre-heater. The diameter of the previous single crystal is obtained by the position of the two intersections and the center position of the previous melting ring. In accordance with the change of the liquid level position of the previous melt, the vertical position of the previous diameter measurement line in the previously recorded image is changed. The first and second diameter measurement values of the pre-single crystal obtained from the positions of the pre-diameter measurement line before and after the position change, respectively, are corrected for the pre-single crystal. Note the diameter of the second measured value.

According to the present invention, it is possible to suppress a change in a diameter measurement value generated when a position in a vertical direction of a diameter measurement line in a captured image is changed in accordance with a change in the position of the liquid surface. Therefore, the stability of the obtained crystal diameter can be improved, and the manufacturing yield of high-quality single crystal can be improved. [Inventive effect]

According to the present invention, there is provided a method and an apparatus for manufacturing a single crystal, and even if the position of a diameter measurement line in a captured image is changed in accordance with a change in the position of a liquid surface, variations in the diameter measurement value can be reduced.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a side sectional view schematically showing the configuration of a single crystal manufacturing apparatus according to an embodiment of the present invention.

As shown in FIG. 1, the single crystal manufacturing apparatus 1 includes a water-cooled reaction chamber 10, a quartz crucible 11 holding a silicon melt 2 in the reaction chamber 10, a graphite crucible 12 holding the quartz crucible 11, and a support for the graphite crucible 12. Rotating shaft 13, Crucible driving mechanism 14 for rotating and lifting quartz crucible 11 through rotary shaft 13 and graphite crucible 12, a heater 15 arranged around graphite crucible 12, and the inside of reaction chamber 10 outside heater 15 Heat-insulating material 16 arranged on the surface, heat shield 17 arranged above quartz crucible 11, wire 18 above crystal crucible 11 and serving as a crystal pulling shaft arranged on the coaxial axis of rotary shaft 13, arranged on the reaction A crystal pulling mechanism 19 above the chamber 10, a camera 20 in the reaction chamber 10, an image processing unit 21 that processes captured images of the camera 20, and a control unit 22 that controls each component in the single crystal manufacturing apparatus 1.

The reaction chamber 10 is composed of a main reaction chamber 10a and an elongated cylindrical pull-up reaction chamber 10b connected to the upper opening of the main reaction chamber 10a. A quartz crucible 11, a graphite crucible 12, a heater 15 and a heat shield 17 are provided. Inside the main reaction chamber 10a. A gas introduction port 10c for introducing an inert gas (purge gas) such as argon gas and a dopant gas into the reaction chamber 10 is provided in the pull-up reaction chamber 10b, and a lower part of the main reaction chamber 10a is provided for A gas discharge port 10d that discharges the ambient gas in the reaction chamber 10. In addition, an observation window 10e is provided on the upper portion of the main reaction chamber 10a, and the growth state of the silicon single crystal 3 can be observed from the observation window 10e.

The quartz crucible 11 is a container made of quartz glass having a cylindrical side wall portion and a curved bottom. In order to maintain the shape of the quartz crucible 11 softened by the heating, the graphite crucible 12 is kept in close contact with the outer surface of the quartz crucible 11 and surrounds the quartz crucible 11. The quartz crucible 11 and the graphite crucible 12 constitute a double-layered crucible that supports a silicon melt in the reaction chamber 10.

The graphite crucible 12 is fixed to the upper end portion of the rotary shaft 13, and the lower end portion of the rotary shaft 13 penetrates the bottom of the reaction chamber 10 and is connected to a crucible driving mechanism 14 provided on the outside of the reaction chamber 10. The graphite crucible 12, the rotating shaft 13, and the crucible driving mechanism 14 constitute a rotating mechanism and a lifting mechanism of the quartz crucible 11. The rotation and lifting operation of the quartz crucible 11 driven by the crucible driving mechanism 14 are controlled by the control unit 22.

The heater 15 is used to melt the silicon raw material filled in the quartz crucible 11 to generate a silicon melt 2 and maintain the molten state of the silicon melt 2. The heater 15 is a resistance heating heater made of carbon, and is provided to surround the quartz crucible 11 in the graphite crucible 12. In addition, a heat insulating material 16 surrounding the heater 15 is provided on the outside of the heater 15, thereby improving the heat insulation property in the reaction chamber 10. The output of the heater 15 is controlled by the control unit 22.

The heat shield 17 is provided to suppress the temperature fluctuation of the silicon melt 2 and to give an appropriate heat distribution near the crystal growth interface, and at the same time prevent the radiant heat from the heater 15 and the quartz crucible 11 from heating the silicon single crystal 3. The heat shield 17 is a member made of a substantially cylindrical graphite, and is provided so as to cover a region above the silicon melt 2 except for the pulling path of the silicon single crystal 3.

The diameter of the opening at the lower end of the heat shield 17 is larger than the diameter of the silicon single crystal 3, thereby ensuring the pulling path of the silicon single crystal 3. In addition, the outer diameter of the lower end of the heat shield 17 is smaller than the diameter of the quartz crucible 11, and the lower end of the heat shield 17 is located inside the quartz crucible 11. Therefore, even if the upper end of the edge of the quartz crucible 11 is raised to The lower end is still above, and the heat shield 17 does not interfere with the quartz crucible 11.

The amount of the molten metal in the quartz crucible 11 decreases as the silicon single crystal 3 grows. However, by increasing the quartz crucible 11 so that the distance (gap) between the molten surface and the heat shield 17 is constant, the molten silicon is suppressed. The temperature of 2 is changed, and the flow velocity of the gas flowing near the melt surface is constant to control the evaporation amount of the dopant from the silicon melt 2. By this gap control, the stability of the crystal defect distribution, the oxygen concentration distribution, and the resistivity distribution in the pulling axis direction of the silicon single crystal 3 can be improved.

Above the quartz crucible 11, a wire 18 serving as a pulling shaft of the silicon single crystal 3 and a crystal pulling mechanism 19 for pulling the silicon single crystal 3 by winding the wire 18 are provided. The crystal pulling mechanism 19 has a function of rotating the silicon single crystal 3 together with the wire 18. The crystal pulling mechanism 19 is controlled by the control unit 22. The crystal pulling mechanism 19 is arranged above the pulling reaction chamber 10b. The metal wire 18 extends from the crystal pulling mechanism 19 through the pulling reaction chamber 10b and extends downward, and the leading end of the wire 18 reaches the internal space of the main reaction chamber 10a. until. FIG. 1 shows the state of the silicon single crystal 3 in the middle of being grown by the wire 18. When the silicon single crystal 3 is pulled, the quartz crucible 11 and the silicon single crystal 3 are respectively rotated, and the metal wire 18 is slowly pulled at the same time, thereby growing the silicon single crystal 3. The crystal pulling speed is controlled by the control unit 22.

A camera 20 is provided outside the reaction chamber 10. The camera 20 is, for example, a CCD camera, and photographs the inside of the reaction chamber 10 through an observation window 10 e formed in the reaction chamber 10. The installation angle of the camera 20 is inclined at a specific angle with respect to the vertical direction, and the camera 20 has an optical axis inclined with respect to the pulling axis of the silicon single crystal 3. That is, the camera 20 photographs the upper region of the quartz crucible 11 including the circular opening of the heat shield 17 and the liquid surface of the silicon melt 2 from an obliquely upward direction.

The camera 20 is connected to the image processing unit 21, and the image processing unit 21 is connected to the control unit 22. The image processing unit 21 calculates the crystal diameter near the solid-liquid interface from the outline pattern of the single crystal appearing in the captured image of the camera 20 or the mirror position of the thermal shield 17 mapped on the molten surface in the captured image. A gap (Gap) is calculated as the distance from the heat shield 17 to the liquid surface position. In order to remove the influence of noise, it is better to use a moving average of the plural measurement values as the gap measurement value for actual gap control.

The method of calculating the gap from the mirror position of the heat shield 17 is not particularly limited, but a conversion formula obtained by approximating the relationship between the mirror position of the heat shield 17 and the gap in a straight line can be prepared in advance, and the heat is used in the crystal pulling process. The mirror position of the shield is substituted into this conversion formula to find the gap. In addition, the gap may be calculated geometrically from the positional relationship between the real image and the mirror image of the heat shield 17 appearing in the captured image.

The control unit 22 controls the crystal pulling speed based on the crystal diameter data obtained from the captured image of the camera 20 to control the crystal diameter. Specifically, when the measured value of the crystal diameter is larger than the target diameter, the crystal pulling speed is increased, and when it is smaller than the target diameter, the pulling speed is slowed. In addition, the control unit 22 controls the movement amount of the quartz crucible 11 (crucible) based on the crystal length data of the silicon single crystal 3 obtained from the sensor of the crystal pulling mechanism 19 and the crystal diameter data obtained from the image captured by the camera 20 Ascent rate).

FIG. 2 is a flowchart showing a manufacturing process of the silicon single crystal 3. FIG. 3 is a schematic cross-sectional view showing the shape of a silicon single crystal ingot.

As shown in FIG. 2, the manufacturing process of the silicon single crystal 3 according to this embodiment includes a raw material melting process S11 for heating the silicon raw material in the quartz crucible 11 with a heater 15 to generate a silicon melt 2, so as to be installed on the metal wire 18. The seed crystal at the tip of the lower part comes into contact with the molten silicon production process S12 of the silicon melt 2. While maintaining the contact state between the seed crystal and the silicon melt 2, it is slowly pulled up to produce a single crystal crystal pulling process (S13 ~ S16) .

In the crystal pulling process, the following steps are carried out in order: a necking process S13 for forming a neck 3a with a thinned crystal diameter for the purpose of non-displacement, and a shoulder 3b with a crystal diameter that gradually increases as the crystal grows. The incubation process S14, the main body incubation process S15 that forms the main body part 3c maintaining a constant crystal diameter, and the tail incubation process S16 that forms the tail part 3d whose crystal diameter gradually decreases as the crystal grows.

Thereafter, the silicon single crystal 3 is cut from the melt surface, and a cooling process S17 for promoting cooling is performed. As described above, a silicon single crystal ingot 3I having a neck portion 3a, a shoulder portion 3b, a main body portion 3c, and a tail portion 3d as shown in FIG. 3 is completed.

Since the type and distribution of the crystal defects contained in the silicon single crystal 3 depend on the ratio V / G of the crystal pulling speed V and the temperature gradient G in the crystal, in order to control the crystal quality in the silicon single crystal 3, it is necessary to Control V / G.

FIG. 4 is a graph showing the general relationship between the types and distribution of V / G and crystal defects.

As shown in FIG. 4, when V / G is large, there are excessive voids, and void defects (COP) are generated as void aggregates. On the other hand, when the V / G is small, there are excess silicon atoms in the inter-lattice, resulting in the formation of a difference between the aggregates of the inter-lattice silicon. In addition, between the region where the COP is generated and the region where the differential clusters are generated, there are three regions of the OSF region, the Pv region, and the Pi region in order from the larger V / G. If a silicon single crystal can be called a defect-free crystal, the entire surface of the silicon single crystal perpendicular to the direction of the pulling axis must be a defect-free area. The "non-defective region" referred to herein is a region that does not contain a Grown-in defect such as a COP, a differential cluster, and the like and does not generate an OSF ring after the heat treatment, and is a Pv region or a Pi region.

In order to control the crystal pulling speed V and to produce defect-free crystals composed of Pv regions or Pi regions with a high yield, it is better that the allowable range of PvPi is as wide as possible. Here, the allowable range of PvPi is, in a broad sense, an allowable range of the crystal pulling speed V that can make any region in the silicon single crystal 3 a Pv region or a Pi region. In a narrow sense, it is orthogonal to the pulling axis direction. The minimum value of the PvPi allowable range in the cross section of the silicon single crystal (the allowable range in the PvPi plane). Generally, because the temperature gradient G in the crystal is constant, the allowable range of PvPi is the width of the V / G width from the Pv-OSF junction to the Pi-diffusion cluster junction in FIG. 4.

The diameter control of the silicon single crystal 3 is mainly performed by adjusting the crystal pulling speed V. In order to suppress the diameter variation, the crystal pulling speed V must be appropriately changed. Therefore, the fluctuation of the pulling speed V cannot be completely absent. Therefore, a PvPi allowable range that allows speed variation to a certain extent is necessary.

On the other hand, the types and distribution of V / G and crystal defects are strongly affected by the thermal environment (ie, hot zone) in the furnace surrounding the crystal. When the hot zone changes with the progress of the crystal pulling process, sometimes Even if the gap is maintained at a certain distance, the desired in-plane allowable range of PvPi cannot be secured. For example, in the middle stage of the main body growing process S15 shown in FIG. 1, there is a single crystal ingot of sufficient length in the space above the silicon melt, and there is no such single crystal ingot at the beginning of the main body growing process S15. Existence, therefore, even if the heat shield 17 is provided, the heat distribution in the space is somewhat different. In addition, in the final stage of the main body growing process S15, in order to prevent the increase in the output of the heater 15 due to the decrease in the silicon melt 2 caused by the decrease of the silicon melt 2 in the crucible, the heat distribution around the crystal also changes. When the hot zone changes like this, even if the gap is maintained at a certain distance, the thermal history in the crystal changes, so the in-plane distribution of crystal defects cannot be maintained constant.

Therefore, in this embodiment, the gap from the top to the bottom of the silicon single crystal ingot is not always maintained at a certain distance, but the gap is changed in accordance with the crystal growth stage. By changing the gap in this way, it is possible to control the in-plane distribution of crystal defects from the top to the bottom of the ingot as desired, suppress the reduction of the allowable range in the PvPi plane, and increase the production yield of defect-free crystals. How to change the gap to suppress the reduction of the permissible range in the PvPi varies depending on the hot zone. Therefore, in order to make the in-plane distribution of crystal defects from the top to the bottom of the crystal constant, it is necessary to consider how to change the hot zone with the progress of the crystal pulling process, and set the gap profile appropriately in accordance with the crystal growth stage. .

5 and 6 are schematic diagrams for explaining a relationship between a gap profile and a crystal defect distribution in a crystal pulling process. FIG. 5 shows a conventional gap fixing control, and FIG. 6 shows a gap variable control according to the present invention. .

As shown in FIG. 5, in the gap fixing control in which the gap is always maintained at a certain distance during the crystal pulling process, the thermal history in the crystal changes due to the change in the hot zone, so the in-plane distribution of crystal defects cannot be maintained as for sure. That is, in the top, middle, and bottom of the silicon single crystal ingot 3I, the in-plane distribution of crystal defects is different. Therefore, the desired PvPi can be ensured in the center of the ingot 3I. In-plane allowable range, but the desired in-plane allowable range of PvPi cannot be ensured at the top and bottom of the ingot 3I.

On the other hand, in the present invention, as shown in FIG. 6, the gap profile is set so that the gap narrows stepwise in accordance with the progress of the crystal pulling process. In particular, the gap contour according to this embodiment is sequentially set: the gap is maintained at a constant first gap fixed control interval S1 from the beginning of the crystal pulling process, and is set in the first half of the main body growing process to make the gap slowly Reduced first gap variable control section S2, second gap fixed control section S3 which maintains the gap constant, second gap variable control section S4 which is provided in the second half of the main body growing process to gradually reduce the gap, until Before the end of the crystal pulling process, the gap is maintained at a constant third gap fixed control section S5. This gap profile is set in accordance with the change in the hot zone, whereby the in-plane distribution of crystal defects from the top to the bottom of the ingot 3I can be maintained as shown in the figure, and the manufacturing yield of defect-free crystals can be improved.

In addition, the above-mentioned gap profile is only an example, and it is not limited to a profile that narrows the gap stepwise in accordance with the progress of the crystal pulling process. Therefore, for example, the gap may be gradually decreased in the first gap variable control section S2, and the gap may be gradually increased in the second gap variable control section S4.

Next, a method for measuring the diameter of the silicon single crystal 3 will be described. In order to control the diameter of the silicon single crystal 3 during the pulling process, the CCD camera 20 is used to capture the interface between the single crystal 3 and the melt surface. From the center of the molten ring and the two luminance peaks of the molten ring generated at the interface The inter-distance distance is used to determine the diameter of the single crystal 3. In addition, in order to control the liquid surface position of the melt 2, the liquid surface position is obtained from the center position of the melting ring. The control unit 22 controls the pulling conditions such as the pulling speed of the wire 18, the power of the heater 15, and the rotation speed of the quartz crucible 11 so that the diameter of the single crystal 3 becomes the target diameter. In addition, the control unit 22 controls the vertical position of the quartz crucible 11 so that the liquid surface position is a desired position.

FIG. 7 is a perspective view schematically showing an image of a boundary between the single crystal 3 and the melt 2 captured by the camera 20.

As shown in FIG. 7, the image processing unit 21 calculates the molten ring 4 from the coordinate position of the center C ₀ of the molten ring 4 generated at the boundary between the single crystal 3 and the melt 2 and the coordinate position at any point on the molten ring 4. Radius r and diameter R = 2r. That is, the image processing unit 21 calculates the diameter R of the single crystal 3 at the solid-liquid interface. The position of the center C ₀ of the melting ring 4 is the intersection of the extension line 5 of the pulling axis of the single crystal 3 and the melt surface.

Since the CCD camera 20 photographs the interface between the single crystal 3 and the melt surface from an obliquely upward direction, the molten ring 4 cannot be photographed as a perfect circle. However, if the CCD camera 20 is set at a predetermined angle accurately at a predetermined position in the design, the slightly elliptical fusion ring 4 can be corrected to a perfect circle based on the visual recognition angle with respect to the melt surface, and The diameter of the molten ring 4 can be calculated geometrically from the correction.

The molten ring 4 is a ring-shaped high-luminance region formed by light reflected by the meniscus, and is generated over the entire circumference of the single crystal 3, but the molten ring 4 on the back side of the single crystal 3 cannot be seen through the observation window 10e. In addition, when the molten ring 4 is viewed from the gap between the opening 17a of the heat shield 17 and the single crystal 3, when the diameter of the single crystal 3 is large, the molten ring is located on the nearest side (lower side in FIG. 7) of the visual recognition direction. A part of 4 cannot be seen because it is hidden behind the heat shield 17. Therefore, the visually recognizable part of the fusion ring 4 is only a part 4L on the left side and a part 4R on the right side when viewed from the visual recognition direction. In the present invention, even when only a part of the molten ring 4 is observed as described above, the diameter can be calculated from this part.

FIG. 8 is a schematic diagram for explaining a method of calculating the diameter R of the molten ring 4.

As shown in FIG. 8, in the calculation of the diameter R of the fusion ring 4, a diameter measurement line L ₁ is set in a two-dimensional image captured by the CCD camera 20. The diameter measurement line L ₁ is a straight line that intersects the melting ring 4 twice and is perpendicular to the extension line 5 of the pulling shaft. The diameter measurement line L _{1 is} set to be lower than the center C _{0 of the} melting ring 4. The Y-axis of the captured image is set in a direction parallel to the extension line 5 of the pull-up axis, and the X-axis is set in a direction orthogonal to the extension line 5 of the pull-up axis. The molten ring 4 shown in FIG. 5 has an ideal shape that matches the outer periphery of the single crystal.

When the coordinates of the center C ₀ of the fusion ring 4 with respect to the origin O (0,0) of the XY coordinates of the captured image are (x ₀ , y ₀ ), the distance from the center C ₀ to the diameter measurement line L ₁ The distance Y = (y ₁ -y ₀ ). In addition, the position of the center C ₀ of the fusion ring 4 may be, for example, the position of the intersection of the horizontal scanning line and the pull-up axis where the distance between the two luminance peaks of the fusion ring is maximum.

Then, two intersection points P ₁ and P ₁ ′ of the diameter measurement line L ₁ and the fusion ring 4 were detected. Assume that the coordinate of the intersection point P ₁ of one of the fusion ring 4 and the diameter measurement line L ₁ is (x ₁ , y ₁ ), and the coordinate of the other intersection point P ₁ ′ is (x ₁ ′, y ₁ ). The approximate positions of the intersection points P ₁ and P ₁ ′ of the fusion ring 4 and the diameter measurement line L ₁ are the positions of the luminance peaks on the diameter measurement line L ₁ . The detailed positions of the intersections P ₁ and P ₁ ′ of the fusion ring 4 and the diameter measurement line L ₁ will be described later.

Then, suppose the distance X between the two intersections P ₁ and P ₁ ′ on the diameter measurement line L ₁ = (x ₁ ′ -x ₁ ). When the diameter of the molten ring 4 is R and the radius is r = R / 2 , We can get the formula (1).

r ² = (R / 2) ² = (X / 2) ² + Y ² ‧‧‧ (1)

Therefore, from the formula (1), the diameter R of the molten ring 4 is as shown in the formula (2).

R = {X ² + 4Y ² } ^1/2 ‧‧‧ (2)

Since the fusion ring is a band-shaped high-luminance region having a certain width, in order to accurately obtain the coordinates of the intersection point with the diameter measurement line L ₁ , the fusion ring 4 must be a line pattern. Therefore, when the intersection of the fusion ring 4 and the diameter measurement line L ₁ is detected, the edge pattern of the fusion ring 4 is detected from the captured image using the reference value of the luminance, and the intersection of the edge pattern and the diameter measurement line is used as the fusion ring. Intersection of 4. The edge pattern of the fusion ring 4 is a pattern composed of pixels having a luminance that matches the reference value of the luminance. The reference value used to define the brightness of the edge pattern may be a value obtained by multiplying the highest brightness in the captured image by a specific coefficient (for example, 0.8).

In the variable gap control for changing the liquid surface position, the position in the captured image of the melting ring generated at the solid-liquid interface also changes in the vertical direction. Therefore, when the vertical position of the diameter measurement line is fixed The position of the melting ring relative to the diameter measurement line changes relatively, and the position of the intersection of the two also changes. However, as described above, if the position of the intersection of the diameter measurement line and the melting ring is changed in accordance with the change in the liquid level position, a diameter measurement error is liable to occur. Therefore, in this embodiment, the diameter measurement line is made to follow the change of the liquid surface position, and at the same time, the distance change amount from the camera to the measurement object is reflected on the diameter measurement result to control the diameter measurement error to a minimum.

FIG. 9 is a graph showing the relationship between the change in the position of the diameter measurement line and the measured value of the crystal diameter. The horizontal axis and the vertical axis respectively show the crystal length and the crystal diameter with relative values based on the reference value.

As shown in FIG. 9, when the crystal pulling condition is controlled so that the crystal diameter is constant, the crystal diameter slightly changes up and down while maintaining a constant value, but at the moment when the diameter measurement line changes, a large change to the negative value side can be seen Propensity. That is, after the position of the diameter measurement line is changed in accordance with the change in the position of the liquid surface, the change in the diameter measurement value immediately becomes large, and it can be known that it is affected by the position change of the diameter measurement line. In addition, the vertical position of the diameter measurement line becomes smaller together with the increase in crystal length, but because the origin of the captured image is set at the upper end, it means that the diameter measurement line moves to the top of the captured image in conjunction with the rise of the liquid level position.

The reason why the diameter measurement value fluctuates as described above is that the control of the diameter measurement line is a non-linear control (step control) for selecting a specific row in the captured image. The change in the position of the liquid level is continuous (linear). In contrast, the change in the diameter measurement line is a discontinuous (non-linear) change in pixel units. Therefore, the position of the diameter measurement line is changed by 1 pixel. The measurement result of the crystal diameter will change. Therefore, in the present embodiment, the crystal diameter measurement value is corrected at a time point when the diameter measurement line has been changed, thereby suppressing the variation in the diameter measurement value.

FIG. 10 is a schematic diagram for explaining a method of correcting a measured value of a crystal diameter obtained immediately after a position of a diameter measuring line is changed.

As shown in FIG. 10 (a), the diameter measurement line L ₁ extends in the horizontal direction and intersects two points of the melting ring 4. This diameter measurement line L ₁ is a pixel row of 1 pixel. When the liquid surface position rises (or falls) by 1 pixel, the vertical position is moved upward (or downward) by 1 pixel. . Here, the position of the liquid level changes continuously, while the change of the diameter measurement line is discontinuous (discrete) and can only be moved in pixel units.

As shown in FIG. 10 (b), when the liquid surface position moves upward and the melting ring 4 also moves 1 pixel from the position of the dotted line to the position of the solid line, the position of the diameter measurement line L ₁ also changes from the position of the dotted line The position of the solid line. The lower diameter dotted line L _1a is a diameter measurement line before the position change, and the upper solid diameter diameter measurement line L _1b is a diameter measurement line after the position change. Based on the measured value of the crystal diameter of the diameter measurement line L _1a below the diameter measurement line before changing the position in the vertical direction, and based on the diameter measurement line after changing the vertical position by 1 pixel The measurement value of the crystal diameter of the upper diameter measurement line L _1b should be the same value because the crystal diameter of the molten ring 4 is measured at almost the same position.

However, in reality, there is a deviation between the diameter measurement values of the two, and the deviation of the measurement values affects the diameter variation after the position of the diameter measurement line L ₁ is changed. For example, when the liquid level position has been raised, even if the actual crystal diameter is the same before and after the liquid level position is raised, the crystal diameter after the liquid level position is raised is measured to be shorter than before the rising. Conversely, the crystal diameter after the liquid level was lowered was measured to be longer than before. Therefore, in this embodiment, a correction coefficient for correcting the deviation of the measured value of the diameter is calculated to correct the measured value of the crystal diameter.

Assuming that the measured value of the crystal diameter before changing the position in the vertical direction is D _Sb and the measured value of the crystal diameter after changing the position of the diameter measurement line by one pixel is D _Sa , the correction coefficient D _{Pi of} the crystal diameter is as follows. D _Pi = D _Sb ÷ D _Sa ‧‧‧ (3)

The corrected crystal diameter D _Sc is a value obtained by multiplying the current crystal diameter D _S by the correction coefficient D _Pi and is as follows. D _Sc = D _S × D _Pi ‧‧‧ (4)

As described above, according to the method for manufacturing a silicon single crystal according to this embodiment, a molten ring appearing at a solid-liquid interface in a single crystal pulling process is photographed, and two intersections of a diameter measurement line and a molten ring set in a captured image are taken. When the crystal diameter is obtained from the position, the position of the diameter measurement line in the vertical direction is changed in accordance with the change in the liquid level position of the melt, and the measured value of the crystal diameter obtained after the position change of the diameter measurement line is corrected. Changes in the diameter measurement value after the position of the diameter measurement line changes. In particular, in the correction of the diameter measurement value, the ratio of the measurement value of the crystal diameter obtained after changing the position of the diameter measurement line to the measurement value of the crystal diameter obtained before changing the position of the diameter measurement line is used as the correction factor. Use this correction factor to correct the measured value of the crystal diameter after the position change. Therefore, you can modify the measured value of the crystal diameter with a simple calculation. Therefore, the stability of the crystal diameter obtained in the variable gap control can be improved, the crystal pulling speed can be stably controlled, and the production yield of high-quality single crystals can be improved.

11 is a schematic diagram for explaining a method of correcting a measured value of a crystal diameter according to a second embodiment of the present invention.

As shown in FIG. 11, the method for correcting the measured value of the crystal diameter according to the present embodiment is characterized in that a plurality of (here, three) diameter measurement lines are used to simultaneously obtain a plurality of diameter measurement values. In addition, the average value of the measured values of the plural diameters was used as the final measured value of the crystal diameter.

In this embodiment, the three diameter measurement lines L ₁ , L ₂ , and L ₃ are continuous in the vertical direction, and there is no space left but adjacent to each other. It is assumed here that the three diameter measurement lines L ₁ , L ₂ , and L ₃ are respectively set on pixel rows PL ₁ , PL ₂ , and PL ₃ that are continuous in the vertical direction in the captured image. When the diameter measurement lines L ₁ , L ₂ , and L _{3 are} moved upward by 1 pixel in accordance with the change of the liquid level position, the three diameter measurement lines L ₁ , L ₂ , and L _{3 are} maintained together in a positional relationship. The diameter measurement lines L ₁ , L ₂ , and L ₃ move to the pixel columns PL ₂ , PL ₃ , and PL ₄ respectively. That is, the diameter of the column from the measurement line L ₁ is moved to the pixel PL ₁ PL _2, the diameter of the measuring line PL ₂ L ₂ moves from pixel column to PL _3, the diameter L ₂ pixels measurement line PL ₃ is moved from column to PL ₄ .

When the correction factor of the crystal diameter is calculated using only one diameter measurement line (refer to FIG. 10), the correction factor must be calculated using the diameter measurement values obtained before and after the position of the diameter measurement line is changed. However, when using adjacent plural diameter measurement lines, you can move other diameter measurement lines to the position before a certain diameter measurement line moves, and use two adjacent diameter measurement lines after the position change to find it. The correction coefficient is calculated from the two diameter measurement values. That is, the correction factor for correcting the measurement value of the crystal diameter is based on the diameter measurement value obtained from the diameter measurement line after changing the vertical position by one pixel, and moving from the new position to the diameter measurement line before moving. The diameter measurement value obtained by the diameter measurement line adjacent to the position is calculated.

For example, since the diameter measurement line L _{1 is} newly moved to the pixel row PL ₂ that had the diameter measurement line L ₂ before the position change, the correction coefficient is obtained based on the diameter measurement lines L ₂ and L ₁ after the position change. In addition, since the diameter measurement line L _{2 is} newly moved to the pixel row PL ₃ that had the diameter measurement line L ₃ before the position change, the correction coefficient is obtained based on the diameter measurement lines L ₃ and L ₂ after the position change. If it is the central diameter measurement line L ₂ , when the diameter measurement lines L ₁ to L ₃ move upward, the correction coefficient can be calculated together with the lower diameter measurement line L ₁ , and the diameter measurement lines L ₁ to L ₃ move downward. In the case of movement, the correction coefficient can be calculated together with the diameter measurement line L ₃ above.

In this way, when the crystal diameter is measured using three adjacent diameter measurement lines L ₁ , L ₂ , and L ₃ , the correction factor can be calculated using the measured values of the crystal diameters simultaneously measured from the molten rings 4 at the same position. There is a diameter measurement error due to time lag, which can improve the accuracy of crystal diameter correction. In addition, the number of diameter measurement lines is not limited to three, and it may be three or more. In addition, in the single crystal pulling process, when the position of the diameter measurement line in the vertical direction can only be moved in one of the upward direction and the downward direction, it may be two.

As mentioned above, although the preferred embodiment of this invention was described, this invention is not limited to the said embodiment, Various changes are possible in the range which does not deviate from the meaning of this invention, Of course, it is also included in the scope of this invention.

For example, in the above-mentioned embodiment, the production of silicon single crystals is taken as an example, but the present invention is not limited to this, but can be applied to the production of various single crystals that are bred by the CZ method.

In the above embodiment, the diameter measurement value is corrected when the liquid level position is changed in the variable gap control. However, the liquid level position is also changed in the fixed gap control. Therefore, the diameter according to the present invention can also be applied. Correction of measured value. [Example]

The single crystal manufacturing apparatus 1 shown in FIG. 1 was used to pull up a silicon single crystal having a diameter of about 300 mm. In the crystal pulling process, switching from gap-fixed control to gap-variable control is performed to slowly increase the liquid level position. In the diameter measurement of a single crystal, as shown in FIG. 8, a diameter measurement line is used to appropriately measure the crystal diameter, and the position of the diameter measurement line is changed in accordance with a change in the position of the liquid surface.

Here, in the comparative example, the measurement value of the crystal diameter was not corrected immediately after the position of the diameter measurement line was changed. However, in the embodiment, the position of the diameter measurement line was immediately changed based on the above-mentioned calculation formula (3). (4) Correct the measured value of crystal diameter. The measurement results of the final crystal diameters in the comparative examples and the examples are shown in Figs. 12 (a) and (b). Note that the vertical axis of FIGS. 12 (a) and (b) indicates the measured value of the crystal diameter as a relative value based on the reference value.

As shown in FIG. 12 (a), in the comparative example in which the measurement value of the crystal diameter was not corrected immediately after the position of the diameter measurement line was changed, the pattern of the diameter fluctuation periodically dropped sharply. It is known that this rapid descent is shifted to the negative value side at the moment when the diameter measurement line moves in accordance with the liquid level position, and is affected by the slow rise of the liquid level position (reduction of the gap) to change the position of the diameter measurement line. The standard deviation σ of the diameter measurement value is 0.1033, the maximum value on the positive side of the diameter fluctuation is 0.248, the maximum value on the negative side is -0.410, and the fluctuation range is 0.658.

As shown in FIG. 12 (b), it can be seen that in the embodiment in which the measurement value of the crystal diameter is corrected immediately after the position of the diameter measurement line is changed, no sharp and periodic decrease is generated in the graph of the diameter change. . That is, the diameter variation at the time point when the position of the diameter measurement line has changed has been removed. The standard deviation σ of the diameter measurement value is 0.0780, the maximum value on the positive value side of the diameter variation is 0.208, the maximum value on the negative value side is -0.197, and the fluctuation range is 0.405.

1‧‧‧Single crystal manufacturing equipment

2‧‧‧ silicon melt

3‧‧‧ silicon single crystal

3a‧‧‧ neck

3b‧‧‧Shoulder

3c‧‧‧Main body

3d‧‧‧ tail

3I‧‧‧Si single crystal ingot

4‧‧‧ molten ring

4L‧‧‧ part of the left side of the melting ring

4R‧‧‧ part of the right side of the melting ring

5‧‧‧Extension line for lifting shaft

10‧‧‧ Reaction Room

10a‧‧‧Main reaction room

10b‧‧‧Tiara reaction chamber

10c‧‧‧Gas inlet

10d‧‧‧Gas exhaust port

10e‧‧‧observation window

11‧‧‧Quartz Crucible

12‧‧‧graphite crucible

13‧‧‧Rotary shaft

14‧‧‧ Crucible drive mechanism

15‧‧‧ heater

16‧‧‧Insulation

17‧‧‧heat shield

17a‧‧‧ opening

18‧‧‧ metal wire

19‧‧‧ Agency

20‧‧‧Camera

21‧‧‧Image Processing Department

22‧‧‧Control Department

L ₁ , L ₂ , L ₃ ‧‧‧ diameter measuring line

L _1a ‧‧‧ Diameter measuring line before position change

L _1b ‧‧‧ Diameter measuring line before position change

PL ₁ ‧‧‧ Pixel

PL ₂ ‧‧‧ Pixel

PL ₃ ‧‧‧ Pixel

R‧‧‧ diameter

S1, S3, S5‧‧‧Gap fixed control interval

S2, S4‧‧‧‧ Gap variable control interval

S11‧‧‧ Raw material melting process

S12‧‧‧Equipping process

S13‧‧‧Neck forming process

S14‧‧‧Shoulder Breeding Process

S15‧‧‧Main body breeding process

S16‧‧‧Tail rearing process

S17‧‧‧Cooling process

[FIG. 1] FIG. 1 is a side cross-sectional view schematically showing a configuration of a single crystal manufacturing apparatus according to an embodiment of the present invention. [Fig. 2] Fig. 2 is a flowchart showing a manufacturing process of the silicon single crystal 3. [Fig. [Fig. 3] Fig. 3 is a schematic sectional view showing the shape of a silicon single crystal ingot. [Fig. 4] Fig. 4 is a diagram showing a general relationship between the types and distribution of V / G and crystal defects. [Fig. 5] Fig. 5 is a schematic diagram for explaining a relationship between a gap profile and a crystal defect distribution in a crystal pulling process, and shows a situation of a conventional gap fixing control. 6] FIG. 6 is a schematic diagram for explaining a relationship between a gap profile and a crystal defect distribution in a crystal pulling process, and shows a state of variable gap control in the present invention. [FIG. 7] FIG. 7 is a perspective view schematically showing an image of a boundary between the single crystal 3 and the melt 2 taken by the camera 20. [FIG. 8 is a schematic diagram for explaining a method of calculating a diameter R of the molten ring 4. [Fig. 9] Fig. 9 is a graph showing a relationship between a change in the position of a diameter measurement line and a measured value of a crystal diameter. [Fig. 10] Fig. 10 is a schematic diagram for explaining a method of correcting a measured value of a crystal diameter obtained immediately after a position of a diameter measuring line is changed. [FIG. 11] FIG. 11 is a schematic diagram for explaining a method of correcting a measured value of a crystal diameter according to a second embodiment of the present invention. [Fig. 12] Fig. 12 is a graph showing the diameter measurement results of silicon single crystals according to Comparative Examples and Examples. (A) shows a comparative example, and (b) shows an example.

Claims (9)

A method for producing a single crystal, which is a method for producing a single crystal based on the Chuklasky method of pulling a single crystal from a melt in a crucible, which is characterized in that it includes: photographing a boundary between the single crystal and the previous melt Step: Find the diameter of the pre-single crystal from the position of at least one diameter measurement line in the horizontal direction set in the captured image and the position of the two intersections of the melting ring appearing at the junction of the previous note and the center position of the previous melting ring Steps; Steps to change the vertical position of the preface diameter measurement line in the preamble captured image in accordance with the change in the liquid level position of the preface melt; preface sheets based on the positions before and after the position change of the preamble diameter measurement line The first and second diameter measurement values of the crystal, and the step of correcting the second diameter measurement value of the previous single crystal; the step of correcting the second diameter measurement value of the former includes calculating the second diameter measurement value of the previous and the first diameter measurement value of the previous diameter. The ratio is used as a step of correction factor; and the step of multiplying the previous correction factor by the second measured diameter value. According to the method for manufacturing a single crystal as described in the first patent application, the step of obtaining the diameter of the previous single crystal is to simultaneously calculate the measured value of the multiple diameter of the previous single crystal using a plurality of diameter measurement lines set in the previous recorded image. ; The step of moving the position of the vertical diameter measurement line in the vertical direction is to move the multiple diameter measurement line in parallel in the vertical direction. As in the method for manufacturing a single crystal as described in the first patent application scope, the step of obtaining the diameter of the pre-single crystal is to use the plural diameter set in the pre-shooting image. The measurement line simultaneously calculates the measured diameter of the complex diameter of the previous single crystal. The step of moving the vertical position of the previously measured diameter measurement line is to move the previously measured plural diameter measurement line in parallel in the vertical direction. According to the method for manufacturing a single crystal according to any one of claims 1 to 3 of the scope of patent application, the first diameter measurement value described above is the value obtained from the diameter measurement line before the position of the previous diameter measurement line changes; The second diameter measurement value is a value obtained from the diameter measurement line after the position of the previous diameter measurement line is changed. As in the method for manufacturing a single crystal as described in the second item of the scope of the patent application, the preamble photographed image includes first to third pixel rows that are continuous in the vertical direction; the preamble plural diameter measurement line includes the first pixel row set in the preamble. The first diameter measurement line and the second diameter measurement line set in the second pixel row of the preamble adjacent to the first pixel row of the preamble; in the step of changing the vertical position of the preamble diameter measurement line, the first in the preamble And the second diameter measurement line are moved to the second pixel row of the preamble and the third pixel row of the preamble adjacent to the second pixel row of the preamble; the first diameter measurement value is the position of the previous plural diameter measurement line. The value obtained from the first diameter measurement line in the previous description; the value measured in the second diameter measurement is the value obtained from the second diameter measurement line after the position change of the plurality of diameter measurement lines in the previous description. According to the method for manufacturing a single crystal described in item 3 of the scope of patent application, the pre-captured image includes the first to third pixel rows that are continuous in the vertical direction; the pre-multiple diameter measurement line includes the first pixel row set in the pre-roll. A first diameter measurement line and a second diameter measurement line set in the second pixel row of the preamble adjacent to the first pixel row of the preamble; In the step of changing the vertical position of the preamble diameter measurement line, the preamble first and second diameter measurement lines are respectively moved to the preamble second pixel row and the preamble third pixel row adjacent to the preamble second pixel row; The first diameter measurement value is the value obtained from the first diameter measurement line after the position change of the previous plural diameter measurement line. The second diameter measurement value is the position change from the previous number after the position change of the previous plural diameter measurement line. The value obtained from the second diameter measuring line. The method for producing a single crystal according to any one of claims 1 to 3, 5, and 6 of the patent application scope, which includes gradually expanding the gap between the heat shield and the former melt disposed above the former melt. Or a narrow gap variable control step; a step of changing the vertical position of the previous diameter measuring line, which cooperates with the previous liquid level position caused by the previous gap variable control step to change the previous diameter measurement line in the previous captured image Vertical position. The method for manufacturing a single crystal according to item 4 of the scope of patent application, which includes a variable gap control step for gradually increasing or decreasing the gap between the heat shield and the aforementioned melt disposed above the aforementioned melt; changing The step of the vertical diameter position of the preamble diameter measurement line is to change the vertical position of the prediameter diameter measurement line in the prerecorded image in accordance with the change of the preface liquid level position caused by the preamble gap variable control step. A single crystal manufacturing device, comprising: a crucible supporting a melt; a heater for heating the melt before recording; The pulling shaft for pulling the single crystal from the previous melt; the crucible lifting mechanism for driving the previous crucible up and down; the crystal pulling mechanism for pulling the single crystal from the previous melt in the previous crucible; the filming of the previous single crystal and the previous melt A camera at the junction; an image processing unit that processes the images captured by the pre-camera; a control unit that controls the pre-heater, pre-roller shaft, and pre-crucible elevator; In the horizontal direction, at least one diameter measurement line and the position of the two intersections of the melting ring appearing at the junction of the previous note and the center position of the previous melting ring are used to obtain the diameter of the previous single crystal; The vertical position of the pre-diameter diameter measurement line in the pre-shooting image; the first and second diameter measurement values of the pre-single crystal obtained based on the position before and after the position change of the pre-diameter measurement line, respectively, to calculate the pre-second diameter The ratio of the measured value to the previous measured diameter of the first diameter as a correction factor is a step of multiplying the previously calculated correction factor by the previously measured second diameter. Before the second note in mind before diameter of the single crystal measured value.