Single crystal manufacturing device and method for controlling a melt surface position

Abstract

A single-crystal manufacturing device for pulling a silicon single crystal from a molten material contained in a crucible by means of a Czochralski process, comprising: at least two different melt surface position measuring devices for measuring the melt surface position of the material melt; control devices for controlling the melt surface position based on the measured melt surface position; and a means of determining whether a measurement deviation has occurred in the melt surface position measuring devices. wherein the at least two different melt surface position measuring devices comprise: a first melt surface position measuring device with a CCD camera; and a second melt surface position measuring device with three CCD cameras that are different from the CCD camera of the first melt surface position measuring device, and wherein the melt surface position is measured simultaneously by the plurality of melt surface position measuring devices, a melt surface position measuring device trained to control the melt surface position is selected from the plurality of melt surface position measuring devices, and the melt surface position measuring device trained to control the melt surface position switches to another melt surface position measuring device when the determining device determines that a measurement deviation has occurred in the selected melt surface position measuring device.

Description

TECHNICAL FIELD

[0001] The present invention relates to a single crystal manufacturing apparatus and a method for controlling a melt surface position. STATE OF THE ART

[0002] In the production of silicon single crystals, the stable fabrication of silicon single crystals with the desired quality is essential to avoid production losses and improve product yield. In particular, due to the high integration of semiconductor devices and the associated advances in miniaturization in recent years, a challenge has arisen in reducing ingrown defects in a silicon single crystal and in stably producing a silicon single crystal with few defects.

[0003] According to the current art, the grown-in defect is determined based on a temperature gradient of a crystal at a growth interface and a growth rate of the silicon single crystal, and the temperature gradient of the crystal at the growth interface must be controlled very precisely.

[0004] To control the temperature gradient of the crystal at the growth interface, a cylindrical thermal insulation component is provided in prior art examples. This component surrounds the perimeter of a grown silicon single crystal above a melt surface and shields against radiant heat. Thus, the crystal temperature gradient can be increased when the crystal is at a high temperature, and a defect-free crystal can be produced quickly.

[0005] As described above, in the silicon single crystal manufacturing apparatus having the thermal insulation component disposed therein, in order to accurately control the crystal temperature gradient at the growth interface, a gap between the melt surface and a lower end of the thermal insulation component must be accurately controlled to a predetermined gap.

[0006] During the growth of a silicon single crystal, the amount of silicon melt contained in a crucible decreases as the crystal grows, and the melt surface position drops. Therefore, according to the prior art, a method for controlling the melt surface position was employed by estimating the amount of the drop corresponding to the growth of the silicon single crystal, issuing a rise instruction to a crucible support shaft according to this estimated value, and raising the crucible position to prevent the melt surface position from dropping, thus maintaining the melt surface position at a constant, predetermined level.

[0007] However, with an increase in the diameter of a crucible shape in conjunction with an increase in the crystal diameter, the melt surface position changes significantly due to variations in the crucible wall thickness and the deformation and expansion of the crucible that occur during a process. Thus, it is difficult to accurately control the melt surface position to maintain it at the predetermined position by solely performing such ramp control of a crucible position according to an estimated value as described above.

[0008] Therefore, a method such as that described in Patent Literature 1 or Patent Literature 2 has been adopted, wherein a CCD camera configured to measure a melt surface position from the outside of a furnace is arranged at an outer portion of a chamber, and the melt surface position is accurately controlled to a predetermined position based on a measurement result of an image supplied from the CCD camera.

[0009] Specifically, Patent Literature 1 discloses a method of imaging a reference reflector disposed at a lower end of a thermal insulation component located above a silicon melt and the reference reflector reflected on the melt surface, which is like a mirror surface, by using an optical device such as a CCD camera and measuring a melt surface portion from this video.

[0010] Furthermore, Patent Literature 3 discloses a method of comparing a crystal diameter measured by a first diameter measuring means having a CCD camera installed at an arbitrary angle to a crystal with a crystal diameter measured by a second diameter measuring means having two CCD cameras arranged side by side at both ends of the crystal, and calculating a melt surface position from a difference between the first crystal diameter and the second crystal diameter.

[0011] As a method for setting a melt surface position detected by each of such measuring methods to a desired position, a method of calculating a deviation of an actual melt surface position from a measured melt surface position and a desired melt surface position and correcting a crucible rising speed is adopted so that the melt surface position can be controlled to a desired position.

[0012] Patent Literature 5 describes CZ devices in which the diameter of the pulled single crystal is determined by multiple CCD cameras. The position of the melt surface is calculated from the CCD camera data and adjusted according to the specifications.

[0013] Patent Literature 6 discloses an apparatus for producing single crystals by the CZ method, in which two CCD cameras are used to determine the diameter of the single crystal. LIST OF CITIONSPATENT LITERATURE Patent Literature 1: JP 2007-290906 A Patent Literature 2: JP 2010-100452 A Patent Literature 3: JP 2013-170097 A Patent Literature 4: JP S64-24089 A Patent literature 5: DE 11 2013 001 066 T5 Patent literature 6: DE 11 2009 002 559 T5 REVELATION OF THE INVENTION: A TASK SOLVED BY THE INVENTION

[0014] To ensure stable and accurate control of a melt surface position, a measurement of the melt surface position, as previously described, is normally always performed as a prerequisite. However, in state-of-the-art manufacturing, the problem frequently arises that a stable measurement cannot be performed due to various occurrences during the manufacturing process (hereinafter also referred to as measurement deviation). Examples include situations where a measurement cannot be performed due to a fault in the melt surface position measuring device, such as a CCD camera installed outside a furnace; faulty measurement of the melt surface position due to a defect in furnace components, such as a reference reflector for measuring the melt surface position; or adhesion of silicon melt to components within a furnace, etc.

[0015] When such a measurement deviation occurs, the melt surface position cannot be controlled to a predetermined position. Thus, silicon single crystals with the desired quality cannot be stably produced.

[0016] Due to this problem, an object of the present invention is to provide a single crystal manufacturing apparatus and a method for controlling a melt surface position that can detect deviations and control a melt surface position even when measurement deviations occur in the measurement of the melt surface position. MEANS FOR SOLVING THE TASK

[0017] To achieve the object, according to the present invention, there is provided a single crystal manufacturing apparatus which pulls a silicon single crystal from a molten material contained in a crucible by a Czochralski method, comprising: at least two different melt surface position measuring means for measuring a melt surface position of the material melt; control means for controlling the melt surface position based on the measured melt surface position; and a determination means for determining whether a measurement deviation has occurred in the melt surface position measuring means, wherein the at least two different melt surface position measuring means comprise: a first melt surface position measuring means with a CCD camera; and a second melt surface position measuring means with three CCD cameras different from the CCD camera of the first melt surface position measuring means, and wherein the melt surface position is measured simultaneously by the plurality of melt surface position measuring devices, a melt surface position measuring device trained to control the melt surface position is selected from the plurality of melt surface position measuring devices, and the melt surface position measuring device trained to control the melt surface position switches to another melt surface position measuring device when the determining device determines that a measurement deviation has occurred in the selected melt surface position measuring device.

[0018] In such an apparatus, when a measurement deviation has occurred in the measurement of the melt surface position, the melt surface position measuring means configured to control the melt surface position switches to another melt surface position measuring means upon detection of this deviation, and thus an apparatus capable of stably controlling the melt surface position can be provided.

[0019] Preferably, the determining means determines whether the measurement deviation has occurred from an amount of change of a value of the melt surface position per unit time, the value being measured by the melt surface position measuring means.

[0020] Furthermore, such a device can reliably determine whether the measurement deviation occurred in the melt surface position measuring instrument.

[0021] Further, according to the present invention, there is provided a method for controlling a melt surface position of a material melt when pulling a silicon single crystal from the material melt contained in a crucible by a Czochralski method, comprising: simultaneously measuring the melt surface position by at least two different melt surface position measuring means; selecting a melt surface position measuring means configured to control the melt surface position from the plurality of melt surface position measuring means; determining whether a measurement deviation has occurred in the selected melt surface position measuring means; and switching the melt surface position measuring means configured to control the melt surface position to another melt surface position measuring means when it is determined that the measurement deviation has occurred.

[0022] In such a method, when a measurement deviation has occurred in the measurement of the melt surface position, the melt surface position measuring means configured to control the melt surface position switches to another melt surface position measuring means upon detecting this deviation, and the melt surface position can thus be stably controlled.

[0023] It is preferable that, when determining whether the measurement deviation has occurred, from an amount of change in a value of the melt surface position per unit time, it is determined whether the measurement deviation has occurred, the value being measured by the melt surface position measuring device.

[0024] Furthermore, such a method can reliably determine whether the measurement deviation occurred in the melt surface position measuring device. EFFECT OF THE INVENTION

[0025] According to the single crystal manufacturing apparatus and the method for controlling a melt surface position of the present invention, when a measurement deviation has occurred in the measurement of a melt surface position, the melt surface position measuring means configured to control the melt surface position switches to another melt surface position measuring means upon detecting this deviation, and thus the melt surface position can be stably controlled. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing an example of a single crystal manufacturing apparatus according to the present invention. Fig. 2 is a schematic view showing an example of the first melt surface position measuring means. Fig. Figure 3 shows a schematic view illustrating an example of the second melt surface position measuring device. Fig. Figure 4 shows an explanatory drawing of the second melt surface position measuring device. Fig. Figure 5 shows a process drawing illustrating an example of a method for controlling a melt surface position according to the present invention. Fig. Figure 6 shows a flowchart illustrating an example of the processing to determine whether a measurement deviation has occurred, when determining whether a measurement deviation has occurred. Fig. Figure 7 shows a graph illustrating the rate of increase of the crucible in the example. Fig. Figure 8 shows a graph illustrating the rate of increase of the crucible in a comparative example. BEST MODE(S) FOR CARRYING OUT THE INVENTION

[0026] An embodiment of the present invention is described below; however, the present invention is not limited to this.

[0027] As described above, when a measurement error has occurred in the measurement of a melt surface position, a problem arises that the melt surface position cannot be controlled to a predetermined position and thus silicon single crystals with a desired quality cannot be stably produced.

[0028] Therefore, the present inventors have repeatedly conducted extensive investigations to solve such a problem. They have thus devised a solution in which the measurement of a melt surface position of a material melt is carried out simultaneously by at least two different melt surface position measuring devices, and the melt surface position measuring device used to control the melt surface position switches to another melt surface position measuring device when it is determined that a measurement deviation has occurred in the melt surface position measuring device used to control the melt surface position.They have thus found that when a measurement deviation occurs in the melt surface position measurement, the melt surface position measuring means configured to control the melt surface position switches to another melt surface position measuring means upon detecting this deviation, thus allowing the melt surface position to be stably controlled. Furthermore, they have extensively investigated the best way to implement such arrangements to implement the present invention.

[0029] A single-crystal manufacturing device according to the present invention is described below. As in Fig. Figure 1 shows a single-crystal manufacturing device 1 consisting of a chamber 2, a crucible 5 with a double structure comprising an inner quartz crucible 3 and an outer graphite crucible 4, a crucible holding shaft 6 holding the crucible 5, a heater 7 arranged on an outer circumference of the crucible 5, a thermal insulation material 8 arranged on an outer circumference of the heater 7, a seed crystal holder 10 for holding a seed crystal 9, and a wire 11 for drawing the seed crystal holder 10, which are arranged coaxially with the crucible holding shaft 6. Furthermore, a cylindrical thermal insulation component 14 for shielding radiant heat is arranged above the molten material 12 contained in the crucible 5 to surround a circumference of a grown silicon single crystal 13.

[0030] Furthermore, the apparatus comprises at least two different melt surface position measuring means 15 that measure a melt surface position of the material melt 12, a control means 16 that controls the melt surface position based on a measured melt surface position, and a determination means 17 that determines whether a measurement deviation has occurred in the melt surface position measuring means 15.

[0031] The following describes an example in which two means, that is, a first melt surface position measuring means 15a and a second melt surface position measuring means 15b, are used as the at least two different melt surface position measuring means 15. However, the present invention is not limited to this, and the at least two different melt surface position measuring means 15 may be, for example, three or more.

[0032] Specifically, as the first and second melt surface position measuring means 15a and 15b, for example, the means described below can be used. However, the present invention is not limited to this, and the at least two different melt surface position measuring means 15 can use the same measuring method or different measuring methods. The case where different measuring methods are used is preferable because the two means do not interfere with each other even if a measurement error occurs in one of them; however, a defect in a device such as a CCD camera can be absorbed even if the same measuring method is used.

[0033] As in Fig. As shown in FIG. 2, in the melt surface position measurement performed by the first melt surface position measuring means 15a, a reference reflector 18 disposed at a lower end of the thermal insulation component 14 and made using a quartz material or the like is used. When the silicon single crystal 13 is manufactured in this state, a reflected image 19 of the reference reflector 18 is displayed on a surface of the melt material 12, which is like a mirror surface.

[0034] At this time, an image of the reference reflector 18 and the reflected image 19 is captured by a CCD camera 20a installed outside a chamber. Additionally, the control means 16 performs image processing of this image result, and a current melt surface position is measured from the distances between the reference reflector 18 and the reflected image 19 provided by the image processing.

[0035] As in Fig. 3, in the melt surface position measurement performed by the second melt surface position measuring means 15b, a CCD camera 20b configured to form an arbitrary angle θ to the silicon single crystal 13 and CCD cameras 20c and 20d configured to be arranged side by side at both ends of the silicon single crystal 13 are used.

[0036] At this point, as in Fig. As shown in Figure 4, when the melt surface position increases from (x) to (x') or decreases to (x''), a first crystal diameter value (a crystal radius A×2) obtained from an image captured by the CCD camera 20b is affected by a change in the melt surface position, and the first crystal diameter value changes to (a crystal radius A'×2) or (a crystal radius A''×2). On the other hand, with respect to a second crystal diameter (B) obtained from images captured by each of two CCD cameras 20c and 20d, a field of view moves up or down solely with respect to a change in the melt surface position, and the second crystal diameter value (B) does not change (Patent Literature 3).

[0037] The amount of change in the melt surface position during crystal production is calculated by the control means 16 from a difference between the two types of generated crystal diameter values ​​due to such a change in the melt surface position and the installation angle θ of the CCD camera 20b. An actual melt surface position can be determined by combining this amount of change with such a melt surface position measurement result before producing the silicon single crystal as described in Patent Literature 4.

[0038] According to the first and second melt surface position measuring instruments 15a and 15b, their melt surface position measuring methods differ from each other and therefore do not affect each other, even if a measurement deviation has occurred in one of them.

[0039] At the time of pulling the silicon single crystal, the melt surface position is measured simultaneously by first and second melt surface position measuring means 15a and 15b. Furthermore, a melt surface measuring means configured to control the melt surface position is selected from the first and second melt surface position measuring means 15a and 15b.

[0040] Regarding the selection at this time, the melt surface position measuring means is determined, for example, on the basis of an application priority of each melt surface position measuring means preset in the control means 16, the stability of the measurement against occurrences occurring during the production of single crystals, among others.

[0041] At this time, a process of a difference between a value of the melt surface position detected by the selected melt surface position measuring means and the predetermined melt surface position setting data is performed, and the difference is thus calculated by the control means 16. A value of the difference detected at this time is a deviation amount of the melt surface position detected by the measurement from a predetermined melt surface position, and this becomes an amount of melt surface position correction performed to adjust the melt surface position to the predetermined position.

[0042] Furthermore, a speed correction amount supplied to the crucible holding shaft 6 for correcting the melt surface position is calculated by an operation of the control means 16. The speed correction amount is added to a crucible position rising speed such that the crucible position rising speed is increased when the melt surface position is lower than the predetermined position and decreased when the melt surface position is higher than the predetermined position. Thus, the melt surface position is maintained at the predetermined position by performing melt surface position correction processing to change the crucible position rising speed according to the amount of deviation of the melt surface position.

[0043] The detection device 17 sequentially checks the measurement data of the appropriately configured device to determine whether a measurement deviation has occurred in the melt surface position measuring device used to control the melt surface position. This allows the measurement deviation to be detected quickly. As a result of the detection, if a measurement deviation is detected, the melt surface position measuring device switches to the other melt surface position measuring device. For example, if the application priority of each melt surface position measuring device is preset in the control device 16, the melt surface position measuring device switches to the one with the second priority, and the control of the melt surface position continues. If no measurement deviation is detected, the control of the melt surface position continues unchanged without changing the melt surface position measuring device.

[0044] Furthermore, it is preferable that the means of determination 17, to ascertain whether a measurement deviation has occurred, is derived from a quantity of the change in a value of the melt surface position per unit time, wherein the value is measured by the melt surface position measuring instrument 15. With such a configuration, it can also be reliably determined whether a measurement deviation has occurred in the melt surface position measuring instrument 15.

[0045] According to such a single-crystal manufacturing device of the present invention, if a measurement deviation has occurred in the measurement of the melt surface position, the melt surface position measuring device designed to control the melt surface position quickly switches to the other melt surface position measuring device and thus the melt surface position can be controlled stably.

[0046] The following describes a method for controlling the position of a melt surface according to the present invention. It is an example using the single-crystal manufacturing device 1 of the present invention as shown in Fig. 1 shown here described, but the present invention is not limited to this.

[0047] First, a high-purity silicon polycrystal is placed in the crucible 5, heated by the heater 7 to about 1420 °C, which is the melting point of silicon, and melted to produce the material melt 12.

[0048] Subsequently, the wire 11 is lowered to bring a tip of the seed crystal 9 held by the seed crystal holder 10 into contact with a surface of the molten material 12. Subsequently, the wire 11 is raised at a predetermined speed while rotating the crucible holding shaft 6 and the wire 11 in a predetermined rotation direction at a rotational speed, and the seed crystal 9 is thereby pulled to grow the silicon single crystal 13 below the seed crystal 9.

[0049] At this time, the melt surface position is measured by the at least two different melt surface position measuring means 15 (first and second melt surface position measuring means 15a and 15b) simultaneously (SP1 in Fig. 5).

[0050] Furthermore, a melt surface measuring means configured to control the melt surface position is selected from the plurality of melt surface position measuring means (SP2 in Fig. 5).

[0051] Any method can be used as a procedure for applying one or more of each melt surface position measuring device, and it is desirable to define a priority of application for each melt surface position measuring device in advance, taking into account, for example, the measurement accuracy of each melt surface position measuring device, the stability of the measurement against occurrences that occur during the production of single crystals, etc., and to determine the mean on the basis of this.

[0052] It is determined whether a measurement deviation has occurred in the selected melt surface position measuring instrument (SP 3 in Fig. 5).

[0053] It is preferable to sequentially determine whether a measurement deviation has occurred in the melt surface position measuring device selected for controlling the melt surface position based on the measurement result data. For example, it is preferable to determine whether a measurement deviation has occurred from the amount of change in a melt surface position value per unit time, where the value is measured by the melt surface position measuring device. With such an arrangement, it is possible to quickly and reliably determine whether a measurement deviation has occurred in the melt surface position measuring device.

[0054] Specifically, in SP3, the determination processing for determining whether the measurement deviation has occurred in the melt surface position measuring means can be carried out according to such a flow chart as in Fig. 6 shown.

[0055] As in Fig. As shown in Figure 6, the detection processing is performed at specified periods corresponding to each predetermined unit time. Regarding the setting of this unit time, it is desirable to set a time as short as possible, approximately one minute or less, with respect to a time required for manufacturing the single crystal, so that the detection of the measurement deviation by the detection processing and the switching processing are performed immediately after the measurement deviation occurs.

[0056] In the detection processing, a difference between a melt surface position measurement result obtained immediately before the detection processing is executed (hereinafter also referred to as the current value) and a previous melt surface position measurement result stored at the time the detection processing was executed in a previous cycle (hereinafter also referred to as the previous value) is calculated. The calculated difference represents the amount of change in the melt surface position during the elapse of the set unit time in the crystal production process (also referred to as the amount of change in the melt surface position).

[0057] If this amount of change in the melt surface position exceeds a detection threshold specified with respect to measurement result data when the measurement and control of the melt surface position are properly performed, that is, within the range of a normal amount of change in the melt surface position, it can be determined that the measurement deviation has occurred.

[0058] Furthermore, when the occurrence of the measurement deviation has been detected, the melt surface position measuring means designed to control the melt surface position changes to the other melt surface position measuring means (SP4 in Fig. 5).

[0059] As described above, if the application priority of the melt surface position measuring means has been defined in advance, the melt surface position measuring means configured to control the melt surface position can switch to one with the second priority upon detecting the occurrence of the measurement deviation in this way. Furthermore, the melt surface position measuring means to which it has been switched is used to continue controlling the melt surface position. If no occurrence of the measurement deviation is detected, the melt surface position control continues unchanged without switching the melt surface position measuring means.

[0060] In this way, according to the melt surface position control method of the present invention, when a measurement deviation has occurred in the measurement of the melt surface position, it is quickly detected, the melt surface position measuring means configured to control the melt surface position switches to the other melt surface position measuring means, and thus the melt surface position can be stably controlled. EXAMPLES

[0061] The present invention will be described in more detail below with reference to an example and a comparative example; however, the present invention is not limited thereto. (Example)

[0062] A silicon single crystal was produced by using such a single crystal manufacturing apparatus of the present invention as in Fig. 1 while controlling a melt surface position according to such a method for controlling a melt surface position of the present invention as shown in Fig. 5 shown.

[0063] As melt surface position measuring means 15 measuring a melt surface position in a crystal growth process, two means with different measuring methods, i.e., first and second melt surface position measuring means 15a and 15b, were respectively installed in the single crystal manufacturing apparatus 1. To control the melt surface position, a measurement result of the first melt surface position measuring means 15a was set for use on a priority basis.

[0064] The first melt surface position measuring means 15a was to use a method as in Fig. 2, the image of such a reference reflector 18 arranged at a lower end of a thermal insulation component 14 and an image 19 of the reference reflector 18 reflected on a melt surface, which is like a mirror surface, was formed by using a CCD camera 20a and measuring a melt surface portion from this video. Furthermore, the second melt surface position measuring means 15b was configured using a method as in Fig. 3 and Fig. 4 is designed to compare a first crystal diameter measured by the first diameter measuring means having a CCD camera 20b installed at 45° to a silicon single crystal 13 with a crystal diameter measured by the second diameter measuring means having two CCD cameras 20c and 20d arranged side by side at both ends of the single crystal 13 and to calculate the melt surface position from this difference.

[0065] Furthermore, 360 kg of a silicon multicrystal was placed in a crucible 5 with a diameter of 812 mm, and the silicon multicrystal was heated and melted by a heater 7 to produce a silicon melt (a material melt 12). The diameter of the silicon single crystal 13 to be produced was set to 300 mm.

[0066] In this example, melt surface position measurements were taken every minute, and a threshold was set to 1 mm, representing the change in melt surface position. Furthermore, the melt surface position correction process during crystal growth was configured so that the correction applied during the 50 mm growth of a straight body length was performed twice: once during the growth of the crystal from 50 mm to 100 mm and again from 100 mm to 150 mm. The crucible ascent rate was set to 0.1 mm / min, and the crucible rate correction was set to -0.01 mm / min based on the melt surface position measurement.

[0067] Furthermore, in a state where the melt surface position correction processing was performed, a measurement deviation was intentionally induced on the first melt surface position measuring means after the completion of the first correction, and changes in the crucible rising speed before and after the occurrence of the measurement deviation were observed, which were Fig. 7 are shown. (Comparison example)

[0068] A silicon single crystal was produced using a conventional method. This means that a single melt surface position measuring device was used, and unlike the example, it was not determined whether measurement errors occurred in the melt surface position measuring device. In addition, as in the example, a measurement error was intentionally induced. Changes in the crucible rise rate before and after the occurrence of the measurement error in the comparative example were observed, and these are shown in Fig. 8 shown.

[0069] Thus, in the comparative example, as in Fig. 8 shown in the second correction processing in which the measurement deviation was intentionally induced, since a measurement result lower than a current melt surface position due to the measurement deviation was applied to the correction processing, the crucible rising speed correction of +0.015 mm / min was performed although a correction amount of -0.01 mm / min should have been applied.

[0070] In contrast, in the example as in Fig.7 shown in the second correction processing in which the first melt surface position measuring means had the measurement deviation, since the control switched to the melt surface position control processing with a measurement result of the second melt surface position measuring means, the correction of -0.01 mm / min was stably applied, and it can be considered that the melt surface position correction processing was performed without being affected by the occurrence of the measurement deviation.

[0071] As previously described with respect to the method for controlling a melt surface position, the use of the present invention enabled the melt surface position to be controlled without being affected by the measurement error that occurs when measuring the melt surface position. Thus, a high-quality silicon single crystal containing a defect-free region could be stably and efficiently provided.

Claims

[1] A single crystal manufacturing apparatus that pulls a silicon single crystal from a molten material contained in a crucible by a Czochralski method, comprising: at least two different melt surface position measuring means for measuring a melt surface position of the material melt; control means for controlling the melt surface position based on the measured melt surface position; and a determination means for determining whether a measurement deviation has occurred in the melt surface position measuring means, wherein the at least two different melt surface position measuring means comprise: a first melt surface position measuring means with a CCD camera; and a second melt surface position measuring means with three CCD cameras different from the CCD camera of the first melt surface position measuring means, and wherein the melt surface position is measured simultaneously by the plurality of melt surface position measuring means, a melt surface position measuring means configured to control the melt surface position is selected from the plurality of melt surface position measuring means, and the melt surface position measuring means configured to control the melt surface position changes to another melt surface position measuring means when the determining means determines that a measurement deviation has occurred in the selected melt surface position measuring means. [2] The single crystal manufacturing apparatus according to claim 1, wherein the determining means determines whether the measurement deviation has occurred from an amount of change of a value of the melt surface position per unit time, the value being measured by the melt surface position measuring means. [3] A method for controlling a melt surface position of a molten material when pulling a silicon single crystal from the molten material contained in a crucible by a Czochralski method, comprising: simultaneously measuring the melt surface position by at least two different melt surface position measuring means; selecting a melt surface position measuring means configured to control the melt surface position from the plurality of melt surface position measuring means; determining whether a measurement deviation has occurred in the selected melt surface position measuring means; and switching the melt surface position measuring means configured to control the melt surface position to another melt surface position measuring means when it is determined that the measurement deviation has occurred. [4] A method for controlling a melt surface position according to claim 3, wherein in determining whether the measurement deviation has occurred, it is determined from an amount of change of a value of the melt surface position per unit time whether the measurement deviation has occurred, the value being measured by the melt surface position measuring means.

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