WO2017110967A1

WO2017110967A1 - Crucible testing device, crucible testing method, silica glass crucible, method for manufacturing silica glass crucible, method for manufacturing silicon ingot, and method for manufacturing homoepitaxial wafer

Info

Publication number: WO2017110967A1
Application number: PCT/JP2016/088285
Authority: WO
Inventors: 俊明須藤; 忠広佐藤; 賢北原; 江梨子北原; 山崎　亨
Original assignee: 株式会社Sumco
Priority date: 2015-12-25
Filing date: 2016-12-22
Publication date: 2017-06-29
Also published as: JPWO2017110967A1; TW201730543A; JP6692526B2

Abstract

The purpose of the present invention is to solve the problem of not being able to test the presence of cracks that may initiate breakage. This crucible testing device that tests breakability of a silica glass crucible includes an acoustic emission (AE) wave detection means which is disposed on a surface of the silica glass crucible, and detects AE waves that are generated when a predetermined external force is applied to the silica glass crucible. The crucible testing device also evaluates the breakability of the silica glass crucible on the basis of the detection result from the AE wave detection means.

Description

Crucible inspection apparatus, crucible inspection method, silica glass crucible, silica glass crucible manufacturing method, silicon ingot manufacturing method, homoepitaxial wafer manufacturing method

The present invention relates to a crucible inspection apparatus, a crucible inspection method, a silica glass crucible, a silica glass crucible manufacturing method, and a silicon ingot manufacturing method, and more particularly to a crucible inspection apparatus, a crucible inspection method, and a silica glass crucible for inspecting crucible fragility. The present invention relates to a method for producing a silica glass crucible, a method for producing a silicon ingot, and a method for producing a homoepitaxial wafer.

<Manufacture of silicon single crystal>
A silicon single crystal (silicon ingot) is manufactured by the Czochralski method (CZochralski) using a silica glass crucible. In the CZ method, first, polycrystalline silicon is filled into a silica glass crucible. Subsequently, the polycrystalline silicon is melted into the silicon melt by heating with a carbon heater or the like disposed around the silica glass crucible. Then, a silicon single crystal seed crystal is brought into contact with the molten silicon melt and gradually pulled up while rotating. Thus, the silicon single crystal is grown by using the seed crystal of the silicon single crystal as a nucleus. The pulling of the silicon single crystal is performed at a temperature of about 1450 to 1500 ° C. This is a temperature exceeding 1200 to 1300 ° C. which is the softening point of the silica glass crucible.

<Silica glass crucible>
A silica glass crucible used in manufacturing the silicon single crystal includes a cylindrical side wall, a curved bottom, and a corner having a higher curvature than the bottom by connecting the side and the bottom. It is a shape and the upper end surface of the side wall part of the silica glass crucible is formed as an annular flat surface. Further, the silica glass crucible includes, for example, a transparent layer in which bubbles cannot be observed based on visual observation or image data, and a bubble-containing layer in which bubbles are observed, from the inner surface to the outer surface of the silica glass crucible. It is comprised with the layer of. Silica glass crucibles are manufactured in various sizes such as 28 inches (about 71 cm), 32 inches (about 81 cm), 36 inches (about 91 cm), and 40 inches (about 101 cm) in diameter.

As described above, the pulling of the silicon single crystal is performed at a temperature exceeding the softening point of silica glass. Therefore, when the silicon single crystal is pulled, the silica glass crucible is deformed. Therefore, generally, a silica glass crucible is used for every pulling of a silicon single crystal. That is, the silica glass crucible needs to be prepared separately for each pulling of the silicon single crystal.

<Method for producing silica glass crucible>
The silica glass crucible as described above is manufactured by using, for example, a rotational mold method. That is, the silica glass crucible is formed by depositing silica powder on the inner surface of a rotating mold (made of carbon) to form a silica powder layer, and arc melting the deposited silica powder layer while reducing the pressure. To manufacture. When performing arc melting, the silica glass crucible having a transparent layer and a bubble-containing layer can be produced by strongly reducing the pressure of the silica powder in the initial stage of arc melting and then reducing the pressure reduction.

<Prior literature>
The silica glass crucible is manufactured by the rotational mold method as described above. Due to such a manufacturing method, the silica glass crucible cannot be manufactured as designed. Therefore, the shape of the manufactured silica glass crucible and the characteristics of the inner surface may be deviated from the design drawing. In addition, as described above, it is necessary to prepare a silica glass crucible separately for each pulling of the silicon single crystal. However, if there is a defect in the manufactured silica glass crucible, the single crystal ratio is reduced when the silicon single crystal is pulled. May cause deterioration. Thus, the silica glass crucible cannot be manufactured as designed, and the manufactured silica glass crucible may have defects that cause deterioration of the single crystal ratio. Therefore, the manufactured silica glass crucible is inspected.

As a technique for inspecting a silica glass crucible, for example, there is Patent Document 1. In Patent Document 1, at least one of an infrared absorption spectrum and a Raman spectrum is measured at a measurement point on the inner surface of a silica glass crucible, and whether or not an abnormal site such as a brown ring is generated based on the obtained spectrum. A method for inspecting a silica glass crucible comprising a step of judging is described. According to Patent Document 1, with the above-described configuration, it is possible to grasp a silica glass crucible where an abnormal site is likely to occur before shipment.

Similarly, as a technique for inspecting a silica glass crucible, there is, for example, Patent Document 2. Patent Document 2 includes a step of measuring a three-dimensional shape of the inner surface of a silica glass crucible with an internal distance measuring unit, a step of (1) measuring a three-dimensional shape of a foreign object, and (2) a step of measuring a three-dimensional distribution of strain. A method for evaluating a silica glass crucible having any of the steps is described. Specifically, (1) in the three-dimensional shape measurement step of a foreign object, images are acquired at a plurality of measurement points, and when it is determined that a foreign object is present in the obtained image, at the position where the image is acquired A plurality of images are acquired by changing the focal position in the thickness direction of the silica glass crucible. Thereby, the three-dimensional position of the foreign material is specified. In the (3) distortion three-dimensional distribution measurement step, the distortion three-dimensional distribution is measured by acquiring distortion images at a plurality of measurement points on the inner surface three-dimensional shape. According to Patent Document 2, by having the above-described configuration, it is possible to specify the three-dimensional position of the foreign matter existing on the inner surface or inside of the crucible, or to determine the three-dimensional distribution of crucible distortion. A crucible evaluation method can be provided.

Similarly, as a technique for inspecting a silica glass crucible, there is, for example, Patent Document 3. Patent Document 3 discloses an inspection method for a silica glass crucible in which ultraviolet light having a wavelength of 365 nm is irradiated on a side surface of a silica glass crucible, and the number of fluorescent spots having a wavelength within a range of 420 nm to 600 nm generated on a silica glass crucible wall surface is measured. Is described. According to Patent Document 4, with the above configuration, impurities localized in the silica glass crucible can be easily detected.

Patent Document 4 discloses a method for manufacturing a glass substrate that can reduce breakage of the glass substrate while increasing the production efficiency of the glass substrate. The method for manufacturing a glass substrate includes a heat treatment step for the glass substrate formed by the downdraw method. In the heat treatment step, the glass substrate is suspended by holding the upper end portion of the glass substrate with a holding member, and the glass substrate is heat-treated while being transported along the transport direction. In the heat treatment step, the glass substrate has a main surface that is curved so as to protrude along the transport direction.

Patent Document 5 discloses a method for producing a glass substrate for a magnetic recording medium that can sufficiently reduce the surface waviness of a short wavelength and the surface waviness of a medium wavelength on the main surface of the glass substrate for a magnetic recording medium. In this manufacturing method, the surface roughness Ra at a measurement wavelength of 2.5 to 80 μm is 0.40 to 1.40 μm, and the surface roughness Ra at a measurement wavelength of 2.5 to 800 μm is 0.40 to 2.00 μm. And a polishing step of polishing the main surface of the glass substrate using a soft polishing pad having a polishing surface.

Patent Document 6 discloses a method for quantitatively evaluating the amount of corrosion of reinforcing steel in a reinforced concrete structure using acoustic emission. In this method, a piezoelectric element sensor is installed in a reinforced concrete structure, and acoustic emission generated due to an external load received by the concrete structure is detected. The peak frequency f obtained by processing the acoustic emission is a hit number Hlow satisfying f1 ≦ f <f2 with respect to an arbitrary frequency f1, f2, f3, f4 (f1 <f2 ≦ f3 <f4), Evaluation is performed in a ratio with the number of hits High that satisfies f3 ≦ f <f4.

Patent Document 7 discloses a defect site detection apparatus using an acoustic emission method that can clarify the position information of a defect site by removing a heat insulating material only at a sensor installation location of an inspection object such as a pipe. This apparatus includes a waveform analysis device having a time-frequency analysis unit, an analysis waveform storage unit, and a calculation unit. The time-frequency analysis unit extracts the highest frequency component that can be extracted from the original sound waveform detected by the sensor using time-frequency analysis in a certain frequency band, and then sequentially extracts the frequency component in a lower frequency band. To separate the waveforms. The analysis waveform storage unit stores the waveform of each frequency band component separated. The calculation unit reads the propagation time of the stored waveform in each frequency band, and calculates the distance between the defect site serving as the sound source and the sensor based on the difference and the propagation speed in each frequency band.

Patent Document 8 discloses a rotating machine bearing diagnostic apparatus using AE that can perform any bearing diagnosis regardless of the magnitude of the load and the rotating mode of the rotating machine. In this apparatus, the detection signal of the AE sensor is amplified and detected, an effective value is calculated by an effective value circuit, and a gate signal for determining a constant speed period of the elevator hoisting machine is output from the comparator to the gate circuit. The control unit calculates a threshold value based on the effective value calculated by the effective value circuit during a predetermined period in the gate signal period, and outputs the threshold value to the comparator via the D / A converter. The comparator outputs a signal when there is a signal equal to or greater than the threshold value among the signals that have passed through the gate circuit, and a pulse is output from the waveform shaping circuit by this signal. Whether or not the bearing is possible is diagnosed by the number of pulses.

Patent Document 9 discloses a plate glass cutting method and apparatus capable of cutting plate glass at a high speed and preventing deterioration in plate glass quality. This method detects the pressing force of the cutter wheel without a time lag by detecting the pressing force of the cutter wheel by a detecting unit such as a piezoelectric element while processing the cutting line of the plate glass. Also, since the vertical movement of the cutter wheel is controlled so as to follow the unevenness of the plate glass by the operation of the pressing means such as a linear motor, the cutter wheel is moved up and down so as to respond at high speed to the control signal from the control unit. .

Patent Literature 10 discloses a composite container inspection method and inspection system. This composite container inspection method is a composite container inspection method including a liner forming a container and a reinforcing layer formed by winding fibers around the liner. This inspection method includes a signal acquisition step of acquiring an acoustic emission signal from an acoustic emission sensor attached to the composite container, and a first indication of a sign of fatigue failure of the liner based on the acoustic emission signal acquired by the signal acquisition step. And a first determination step for determining whether or not the above condition is satisfied. The first condition is a condition determined based on the energy of acoustic emission.
Here, there is a method for inspecting scratches by ultrasonic flaw detection. In ultrasonic flaw detection, a flaw of an object is found from ultrasonic waves that propagate by returning the ultrasonic wave to the object. However, it cannot be determined whether cracks will grow. For this reason, even if an ultrasonic flaw detection is applied to a silica glass crucible, it is impossible to find a growing crack accompanied by a crack in the silica glass crucible, which is unsuitable for inspection of a silica glass crucible.

JP 2013-139353 A JP 2014-91640 A JP-A-8-283092 JP 2016-169136 A JP 2014-154187 A JP 2011-133448 A Japanese Patent Laid-Open No. 2003-232728 JP 09-210859 A JP 08-225333 A International Publication No. 2014/057987 Special table 2014-528643 gazette JP 2008-219002 A

<Problems with cracks>
In a silica glass crucible, when stress is applied to a silica glass crucible having growing cracks, the cracks grow and eventually the silica glass crucible is broken. In particular, when pulling up a silicon single crystal, about 400 kg of polycrystalline silicon is filled in the silica glass crucible, and therefore, a force pushed by the polycrystalline silicon from the inside acts on the silica glass crucible. In the process of pulling up the silicon single crystal, the silica glass crucible may be cracked or cracked, and the silicon melt in the crucible may leak out. It is known that such glass breakage is caused by the presence of cracks as starting points of cracks.

If cracks grow during the pulling of the silicon single crystal and cracks or cracks occur in the silica glass crucible, it will cause leakage of molten polycrystalline silicon.
The crack as the starting point of the crack as described above may be formed at the stage of filling the silica glass crucible with polycrystalline silicon, but may also be formed in the process of manufacturing the silica glass crucible. Therefore, in order to prevent the situation where the silica glass crucible is broken, the silica glass crucible is inspected at the stage where the silica glass crucible is manufactured, and the crack formed in the silica glass crucible. It is necessary to inspect for the presence or absence of this.
In particular, it is very important to accurately find cracks (including microcracks) that lead to cracking of the silica glass crucible before the silicon single crystal is pulled (before use).

However, with the techniques described in Patent Documents 1 to 3, it was not possible to inspect the presence of minute cracks that could not be confirmed from visual observation or image data. As a result, a microcrack exists in the silica glass crucible for pulling up the silicon single crystal, and the microcrack may cause damage to the silica glass crucible.

Here, large cracks on the surface of the silica glass crucible can be found by visual inspection and image inspection, but microcracks and cracks existing inside the crucible wall cannot be detected by visual inspection and image inspection. As described above, there has been a problem that the existence of a crack that may be a starting point of a crack cannot be sufficiently inspected.

In addition, in the technique described in Patent Document 4, the planar glass substrate before the heat treatment has only a predetermined strength to be inspected by the AE method. Is not considered. In the technique described in Patent Document 5, an AE sensor is merely used for inspecting whether or not the manufactured glass substrate (plane) for a magnetic recording medium has a predetermined quality.

Moreover, in the technique described in Patent Document 6, the amount of corrosion of reinforcing bars in a simple rectangular parallelepiped reinforced concrete structure is only inspected by using AE. Not considered. Moreover, in the technique described in Patent Document 7, only AE is used for inspection of piping and the like.

In the technique described in Patent Document 8, only AE is used for inspection of elevator bearings. Moreover, in the technique described in patent document 9, only the AE sensor is used for the detection of the unevenness of the plate glass. Moreover, with the technique described in patent document 10, only the AE sensor is utilized for the inspection of the fatigue failure of the steel container.

As described above, the technologies described in Patent Documents 4 to 10 do not consider the shape and bubble layer peculiar to the crucible. Therefore, the AE occurs, for example, by changing the sensor position for the crucible and how to apply external pressure. The ease of crucible cracking cannot be evaluated taking into account the position.

Accordingly, an object of the present invention is to provide a crucible inspection apparatus, a crucible inspection method, a silica glass crucible, and a silica glass crucible that can solve the problem that it is impossible to inspect the presence of a crack that may become a starting point of a crack. It is providing the manufacturing method of this, the manufacturing method of a silicon ingot, and the manufacturing method of a homoepitaxial wafer.

For the purpose of inspecting microcracks that may be a starting point for cracking of a silica glass crucible, the crucible inspection apparatus according to one aspect of the present invention is
Inspecting the ease of cracking of a silica glass crucible comprising a cylindrical side wall, a curved bottom, and a corner provided between the side wall and the bottom and having a curvature higher than the curvature of the bottom. A silica glass crucible inspection device,
A configuration is adopted in which an AE wave detecting means is provided which is installed on the surface of the silica glass crucible and detects an AE (Acoustic Emission) wave generated when a predetermined external force is applied to the silica glass crucible.
Here, the inspection object using the conventional AE is used at room temperature, but the inspection object silicon single crystal pulling temperature of the present invention is high (the silicon melt is 1400 ° C. or higher, the temperature of the silica glass crucible). Is a silica glass crucible that can withstand a long time (100 hours or more).
This silica glass crucible is used in a state of being fitted into a carbon susceptor in a pulling device. Therefore, even if it is 1600 degreeC, it does not fall outside by the carbon susceptor outside the silica glass crucible, and can be used as a crucible. On the other hand, quartz glass alone is deformed at about 1200 ° C. That is, the silica glass crucible is used in a completely different environment from general quartz glass, and it is necessary to detect microcracks that are so small that they cannot be compared with an object used at room temperature.
Depending on the usage conditions for a long time at a high temperature, stress may be concentrated in the curved portion in the silica glass crucible, and it is necessary to detect minute microcracks in order to withstand the stress.
In addition, conventional inspection objects using AE waves are composed of simple materials such as blocks and pipes, but silica glass crucibles have side walls, corners, and bottoms, and are composed of curved surfaces. In addition, it has a layer structure of a transparent layer and a bubble layer. For this reason, the conventional method cannot be applied as it is.
In addition, by inspecting microcracks using AE waves, non-destructive silica glass crucibles that are actually used for pulling up silicon single crystals at high temperatures for a long time are inspected without cutting sample pieces from the silica glass crucible. Can be selected. Thereby, it is possible to prevent troubles such as high temperature silicon melt leaking into the silicon single crystal pulling furnace (CZ furnace) due to cracking or opening of the silicon single crystal.

In addition, the crucible inspection method according to another embodiment of the present invention,
AE wave inspection means for inspecting AE waves is installed on the surface of the silica glass crucible,
Apply a predetermined external force to the silica glass crucible,
AE (Acoustic Emission) wave generated when the predetermined external force is applied to the silica glass crucible is detected.
The structure is taken.

In addition, the silica glass crucible which is another embodiment of the present invention,
A configuration is adopted in which the number of defects that generate AE waves when an external force is applied is equal to or less than a predetermined threshold.

Moreover, the method for producing a silica glass crucible which is another embodiment of the present invention,
An AE wave inspection means for inspecting the AE wave is installed on the surface of the silica glass crucible, a predetermined external force is applied to the silica glass crucible, and an AE (Acoustic Emission) wave generated when the predetermined external force is applied to the silica glass crucible. It has a configuration of having a detecting step.

Moreover, the method for producing a silicon ingot according to another embodiment of the present invention,
A configuration is adopted in which the method includes the step of pulling up the silicon single crystal using the silica glass crucible manufactured by the silica glass crucible manufacturing method described above.

In addition, a homoepitaxial wafer according to another embodiment of the present invention includes a step of forming a substrate portion by a wafer formed by cutting out a silicon ingot manufactured by the above method, and a silicon single crystal homoepitaxial layer on the substrate portion Forming a step.

The present invention is configured as described above, and can solve the problem that the presence of a crack that may be a starting point of a crack cannot be inspected. By this, even if it is a microcrack that cannot be seen by visual inspection or image inspection, or a microcrack that exists inside the crucible wall, the inside surface and wall portion of these silica glass crucibles can be inspected using AE waves. Internal microcracks can be found.

It is a figure which shows an example of a structure of the silica glass crucible used as the test object in the 1st Embodiment of this invention. It is a figure which shows an example of a structure of the crucible inspection apparatus in the 1st Embodiment of this invention. It is a figure which shows an example of a structure of the AE sensor shown in FIG. It is a figure which shows an example of a mode at the time of installing the AE sensor shown in FIG. 2 in a silica glass crucible. It is a figure which shows an example of a structure of the AE wave analysis apparatus shown in FIG. It is a figure for demonstrating an example of the measurement by the AE wave intensity measurement part shown in FIG. It is a figure for demonstrating an example of the measurement of the AE wave by the AE wave generation frequency measurement part shown in FIG. It is a figure for demonstrating an example of calculation of the generation | occurrence | production position by the AE wave generation | occurrence | production position calculation part shown in FIG. It is a flowchart which shows an example of operation | movement of the crucible test | inspection apparatus in 1st Embodiment. (A)-(c) is a schematic diagram explaining the manufacturing method of the silicon single crystal using the silica glass crucible concerning this embodiment. It is a schematic diagram which illustrates the ingot of a silicon single crystal. (A)-(c) is a schematic diagram explaining pull-up control. It is a figure which shows the variation | change_quantity of the internal diameter of a crucible. It is a schematic diagram explaining the condition where various defects generate | occur | produce based on the Boronkov theory. It is a schematic diagram which shows the relationship between the pulling speed at the time of single crystal growth, and defect distribution. It is a schematic cross section which illustrates an epitaxial wafer. It is a flowchart which illustrates the process from crucible manufacture to wafer manufacture. It is a figure which shows the relationship between AE wave generation number and a maximum energy value.

[Embodiment 1]
A crucible inspection apparatus 2, a crucible inspection method, a silica glass crucible 1, a method for manufacturing a silica glass crucible, and a method for manufacturing a silicon ingot according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram illustrating an example of the configuration of the silica glass crucible 1. FIG. 2 is a diagram illustrating an example of the configuration of the crucible inspection apparatus 2. FIG. 3 is a diagram illustrating an example of the configuration of the AE sensor 21. FIG. 4 is a diagram illustrating an example of a state when the AE sensor 21 is installed in the silica glass crucible 1. FIG. 5 is a diagram illustrating an example of the configuration of the AE wave analyzer 23. FIG. 6 is a diagram for explaining an example of measurement by the AE wave intensity measurement unit 231. FIG. 7 is a diagram for explaining an example of AE wave measurement by the AE wave generation number measurement unit 232. FIG. 8 is a diagram for explaining an example of calculation of the AE wave generation position by the AE wave generation position calculation unit 233. FIG. 9 is a flowchart showing an example of the operation of the crucible inspection apparatus 2.

In the first embodiment of the present invention, a crucible inspection apparatus 2 that inspects and evaluates the fragility of the silica glass crucible 1 will be described. As will be described later, the crucible inspection apparatus 2 in the present embodiment has an AE (Acoustic Emission) sensor 21 and detects an AE wave generated when a predetermined external force is applied to the silica glass crucible 1. With this configuration, the crucible inspection apparatus 2 inspects and evaluates the ease of cracking of the silica glass crucible 1 based on the detection result of the AE wave by the AE sensor 21.

<1. Silica glass crucible 1>
As shown in FIG. 1, a silica glass crucible 1 to be inspected / evaluated by the crucible inspection apparatus 2 in this embodiment includes a cylindrical side wall portion 11, a curved bottom portion 12, a side wall portion 11 and a bottom portion 12. And a corner portion 13 having a higher curvature than the bottom portion 12. Moreover, the upper end surface of the side wall part 11 of the silica glass crucible 1 is formed as an annular flat surface.

The silica glass crucible 1 includes a transparent layer 111 in which bubbles are not observed and a bubble-containing layer 112 in which bubbles are observed from the inner surface toward the outer surface of the silica glass crucible 1 based on visual observation or image data. The silica glass crucible 1 has various sizes such as 28 inches (about 71 cm), 32 inches (about 81 cm), 36 inches (about 91 cm), and 40 inches (about 101 cm) in diameter.

Such a silica glass crucible 1 is manufactured using, for example, a rotational mold method. That is, the silica glass crucible 1 forms a silica powder layer by depositing silica powder on the inner surface of a rotating mold (made of carbon), and arc-melting the deposited silica powder layer while reducing the pressure. Manufactured by. When performing arc melting, silica powder is strongly depressurized in the initial stage of arc melting, and then the pressure is weakened, whereby the silica having the transparent layer 111 on the inner surface side and the bubble-containing layer 112 on the outer surface side. A glass crucible 1 can be manufactured. In addition, since the silica glass crucible 1 is manufactured by the method as described above, for example, unmelted silica powder is attached to the outer surface layer of the silica glass crucible 1. That is, the outer surface layer of the silica glass crucible 1 has a rough roughness.

Silica powder used for the production of the silica glass crucible 1 includes natural silica powder produced by pulverizing natural quartz and synthetic silica powder produced by chemical synthesis. Natural silica powder contains impurities, but synthetic silica powder has high purity. On the other hand, synthetic silica glass obtained by melting synthetic silica powder has a lower viscosity at high temperature than silica glass obtained by melting natural silica powder. Thus, natural silica powder and synthetic silica powder have a plurality of differences in their properties. When manufacturing the silica glass crucible 1, natural silica powder and synthetic silica powder can be used properly.

<2. Crucible inspection device 2>
As shown in FIG. 2, the crucible inspection apparatus 2 in the present embodiment includes an AE sensor 21 (AE wave detection means), an amplifier 22, and an AE wave analysis apparatus 23. The AE sensor 21 and the amplifier 22 are connected so that an electric signal can be transmitted. The amplifier 22 and the AE wave analyzer 23 are also connected so as to be able to transmit electrical signals. FIG. 2 shows a case where the crucible inspection apparatus 2 has one AE sensor 21 as an example of the configuration of the crucible inspection apparatus 2. However, the number of AE sensors 21 included in the crucible inspection apparatus 2 is not limited to one. The crucible inspection apparatus 2 may have an arbitrary number of AE sensors 21 of two or more.

<2-1. AE sensor 21>
The AE sensor 21 is installed on the surface of the silica glass crucible 1 and detects an AE wave generated when a predetermined external force is applied to the silica glass crucible 1. The AE sensor 21 can be configured to detect the AE wave so that the time when the AE wave is detected can be discriminated.

Referring to FIG. 3, the AE sensor 21 includes, for example, a piezoelectric element 211, a receiving plate 212, and a connector 213. As shown in FIG. 3, a piezoelectric element 211 is provided on one surface of the receiving plate 212, and the piezoelectric element 211 and the connector 213 are connected so that a current can flow. As shown in FIG. 4, the receiving plate 212 is in contact with the silica glass crucible 1 on the other surface (the surface opposite to the side on which the piezoelectric element 211 is provided).

Specifically, the AE sensor 21 in the present embodiment is installed on the inner surface of the silica glass crucible 1. That is, the receiving plate 212 of the AE sensor 21 is installed on the inner surface of the silica glass crucible 1 so as to be in contact with the transparent layer 111 of the silica glass crucible 1. As described above, the outer surface layer of the silica glass crucible 1 has a rough roughness. In order to increase the detection accuracy of the AE wave, it is desirable that the installation surface does not have roughness. Therefore, by installing the AE sensor 21 on the inner surface of the silica glass crucible 1 as described above, Compared with the case where it is installed on the outer surface of the silica glass crucible 1, it is possible to detect the AE wave with higher accuracy.

The piezoelectric element 211 converts a force applied to itself into a voltage. Specifically, the piezoelectric element 211 in the present embodiment detects distortion of the silica glass crucible 1 due to propagation of AE waves and converts the distortion into a voltage. That is, the piezoelectric element 211 detects an AE wave and generates an electric signal (AE signal) corresponding to the AE wave. The piezoelectric element 211 in the present embodiment is, for example, a piezoelectric ceramic, and is made of, for example, lead zirconate titanate (Pb (Zr, Ti) O3).

The receiving plate 212 is provided with a piezoelectric element 211 on one surface, and comes into contact with the silica glass crucible 1 on the other surface. The receiving plate 212 is distorted by AE waves propagating through the silica glass crucible 1. As the receiving plate 212 is distorted in this way, the AE wave generated in the silica glass crucible 1 is transmitted to the piezoelectric element 211. The receiving plate 212 is ceramics, for example.

Connector 213 connects piezoelectric element 211 and amplifier 22 which is an external device. As described above, the piezoelectric element 211 is connected to the connector 213, and the AE signal generated by the piezoelectric element 211 is transmitted to the amplifier 22 via the connector 213.

<2-1-1. Number of installed AE sensors 21>
In the present embodiment, at least three AE sensors 21 described above are installed in the silica glass crucible 1. As will be described later, by using at least three AE sensors 21, it is possible to specify the position of the AE occurrence position on the plane when the three-dimensional silica glass crucible 1 is developed on the plane.

In addition, at least three AE sensors 21 are installed on the side wall part 11, the bottom part 12, and the corner part 13, for example. By installing in this way, it becomes possible to specify the generation | occurrence | production position of AE more reliably.
For example, with respect to the cylindrical side wall portion 11, a plurality of AE sensors 21 are arranged at equal intervals in the circumferential direction of the cylinder. Further, the AE sensor 21 is applied to the corner portion 13 where internal residual stress is likely to be accumulated in the silica glass crucible 1 and the bottom portion 12 where pressure is easily applied when filling a material (polycrystalline silicon) for pulling up the silicon single crystal. Is preferably arranged.
In particular, if there are microcracks in the curved corner portion 13 and the bottom portion 12 of the silica glass crucible 1, the silica glass crucible 1 is likely to break when the silicon single crystal is pulled. Therefore, it is desirable to inspect the ease of cracking of the silica glass crucible 1 by installing the AE sensor 21 around the connection portion between the corner portion 13 and the bottom portion 12.

<2-2. Amplifier 22>
The amplifier 22 amplifies the AE signal received from the AE sensor 21. The AE signal amplified by the amplifier 22 is transmitted to the AE wave analyzer 23. In the present embodiment, the configuration of the amplifier 22 is not particularly limited.

<2-3. AE Wave Analyzer 23>
The AE wave analyzer 23 receives the AE signal amplified by the amplifier 22. Then, the AE wave analysis device 23 measures the strength of the AE wave based on the received AE signal, counts the number of times the AE wave is detected, and is easy to break the silica glass crucible 1 based on the detection result. Or evaluate.

The AE wave analysis device 23 includes, for example, a filter, an in-device amplifier, an envelope detection unit, and the like (not shown). The AE wave analyzer 23 removes a signal having a frequency unnecessary for the inspection from the AE signal received from the amplifier 22 using a filter. Then, the AE wave analyzing device 23 amplifies the removed AE signal with an in-device amplifier. Thereafter, the AE wave analyzer 23 performs processing such as measurement using the amplified AE signal. Further, the AE wave analysis device 23 extracts the envelope of the amplified AE signal by the envelope detection means (specifically, for example, after half-rectifying the negative portion of the AE signal, the envelope detection is performed). Do). The AE wave analyzer 23 can also perform processing such as measurement using the extracted envelope.

FIG. 5 shows an example of the main configuration of the AE wave analyzer 23. Referring to FIG. 5, the AE wave analysis device 23 includes, for example, an AE wave intensity measurement unit 231, an AE wave generation frequency measurement unit 232, an AE wave generation position calculation unit 233 (position specifying unit), and a crucible evaluation unit. 234 (crucible evaluation means) and a measurement result storage unit 235. Note that the AE wave analysis device 23 includes a central processing unit (CPU: Central Processing Unit) (not shown) and a storage device, and the CPU executes a program stored in the storage device, thereby realizing the above-described units. The AE wave analysis device 23 may have a configuration other than the above-exemplified examples, or may be configured by a part of the above-exemplified examples (for example, the AE wave analysis device 23 has an AE wave strength). And a measuring unit 231 and a crucible evaluating unit 234.

<2-3-1. AE Wave Strength Measurement Unit 231>
The AE wave intensity measurement unit 231 measures the intensity of the AE wave detected by the AE sensor 21. For example, the AE wave intensity measurement unit 231 measures the intensity of the AE wave based on the AE signal waveform amplified by the in-device amplifier. FIG. 6 is an example of an AE signal waveform after amplification by the in-device amplifier. As shown in FIG. 6, for example, the AE wave intensity measurement unit 231 measures the maximum amplitude, which is the largest amplitude among the AE signal waveforms, as the intensity of the AE wave. The maximum amplitude represents the energy level (dB) of the AE wave. When the distance between the AE sensor 21 and the AE generation position is equal, the larger the maximum amplitude, the larger the energy released by the AE generation source.

Note that the AE wave intensity measurement unit 231 may be configured to measure the AE average value as the AE wave intensity instead of the maximum amplitude. The AE average value can be calculated by, for example, averaging the envelope waveform extracted by envelope detection. Further, the AE wave intensity measuring unit 231 may be configured to measure the AE effective value (effective value, root mean square value, RMS) as the AE wave intensity.

<2-3-2. AE wave generation frequency measurement unit 232>
The AE wave generation number measurement unit 232 measures the number of detections of the AE wave detected by the AE sensor 21. For example, the AE wave generation frequency measurement unit 232 measures the number of detections of the AE wave based on the envelope waveform extracted by envelope detection and a predetermined threshold value (a value larger than the noise signal). . FIG. 7 is an example of an envelope waveform extracted by envelope detection. As illustrated in FIG. 7, for example, the AE wave generation number measurement unit 232 measures the number of detections of the AE wave by counting the number of times exceeding the threshold value in the envelope waveform. For example, in the case of FIG. 7, the AE wave generation number measurement unit 232 measures that the AE wave has been detected twice.

Note that the AE wave generation frequency measurement unit 232 may be configured to calculate, for example, the AE wave generation frequency per unit time obtained by dividing the measured frequency by the measurement time.

<2-3-3. AE wave generation position calculation unit 233>
The AE wave generation position calculation unit 233 calculates the generation position of the AE wave. For example, the AE wave generation position calculation unit 233 calculates the generation position of the AE wave based on the difference in detection time when the plurality of AE sensors 21 installed in the silica glass crucible 1 detect the AE wave. Specifically, the AE wave generation position calculation unit 233 determines the generation position of the AE wave based on the difference in detection time when each AE sensor 21 detects the AE wave and the sound velocity V in the silica glass crucible 1. Is calculated.

FIG. 8 is a diagram for explaining an example of the calculation of the AE wave by the AE wave generation position calculation unit 233. FIG. 8 shows one example when calculating the generation position of the AE wave in one dimension as an example for explaining the calculation method of the generation position of the AE wave. The AE sensor 21-1 and the AE sensor 21- 2 is set at a known coordinate, and an AE wave generated from a crack 3 existing on an unknown coordinate x is detected. As shown in FIG. 8, for example, it is assumed that the AE sensor 21-1 is installed at the coordinate k1, and the AE sensor 21-2 is installed at the coordinate k2. Also, assume that the AE sensor 21-1 detects an AE wave generated from the crack 3 at time t1, and the AE sensor 21-2 detects an AE wave generated from the crack 3 at time t2. In this case, the time difference t1-t2 between the detection time t1 by the AE sensor 21-1 and the detection time t2 by the AE sensor 21-2 is the distance between the AE sensor 21-1 and the crack 3 xx1 and AE. This is caused by the difference between xx2 which is the distance between the sensor 21-1 and the crack 3. Therefore, the AE wave generation position calculation unit 233 can determine the position of the crack 3 by solving the expression V (t1−t2) = | x−x1 | − | x−x2 |. The speed of sound waves in the silica glass crucible 1 is about 5700-5900 m / s for longitudinal waves and about 3700 m / s for transverse waves.

For the same reason as described above, the AE wave generation position calculation unit 233 uses the three AE sensors 21 to calculate the two-dimensional position of the crack 3 based on the positional relationship between the three AE sensors and the difference in detection time. I can do it. Here, the two-dimensional position is a coordinate on a plane when the three-dimensional silica glass crucible 1 is developed on the plane. On the other hand, the actual silica glass crucible 1 has a three-dimensional shape (a cylindrical side wall portion 11, a curved bottom portion 12, a corner portion 13 provided between the side wall portion 11 and the bottom portion 12 and having a higher curvature than the bottom portion 12). It is. Therefore, the AE wave generation position calculation unit 233 returns (reversely converts) the calculated two-dimensional position of the crack 3 to the actual three-dimensional shape of the silica glass crucible 1 to calculate the three-dimensional position of the crack 3. Also good. Thereby, the three-dimensional shape of the silica glass crucible 1 and the position of the crack 3 can be accurately grasped.

<2-3-4. Crucible evaluation unit 234>
The crucible evaluation unit 234 evaluates the ease of cracking of the silica glass crucible 1 based on the measurement, measurement, and calculation results by the AE wave intensity measurement unit 231, the AE wave generation frequency measurement unit 232, and the AE wave generation position calculation unit 233. To do.

For example, the crucible evaluation unit 234 compares the value of the measurement result obtained by the AE wave intensity measurement unit 231 with a strength threshold value (arbitrarily adjusted value) stored in advance. And when the value of a measurement result exceeds the strength threshold, crucible evaluation part 234 evaluates that silica glass crucible 1 is easy to break. Thus, the crucible evaluation unit 234 evaluates the ease of cracking of the silica glass crucible 1 based on the strength of the AE wave generated when a predetermined external force is applied to the silica glass crucible 1, for example.

When the result of measurement by the AE wave intensity measurement unit 231 is equal to or greater than a preset threshold, if the silicon single crystal is actually pulled up using the silica glass crucible 1, the silica glass crucible 1 may be broken in the middle. Becomes stronger.

Also, for example, the crucible evaluation unit 234 compares the value of the measurement result obtained by the AE wave generation frequency measurement unit 232 with a frequency threshold value (arbitrarily adjusted value) stored in advance. And when the value of a measurement result exceeds the frequency threshold, crucible evaluation part 234 evaluates that silica glass crucible 1 is easy to break. Thus, the crucible evaluation part 234 evaluates the ease of cracking of the silica glass crucible 1 based on the number of AE waves generated when a predetermined external force is applied to the silica glass crucible 1, for example.

As a result of measurement by the AE wave generation frequency measuring unit 232, when AE waves of a preset number of times or more are measured, when the silicon single crystal is actually pulled up using the silica glass crucible 1, the silica glass crucible 1 breaks along the way. The risk of getting stronger.

Further, for example, the crucible evaluation unit 234 can evaluate the ease of cracking of the silica glass crucible 1 based on the calculation result by the AE wave generation position calculation unit 233. For example, it is conceivable that the ease of cracking of the silica glass crucible 1 changes depending on the position of a crack generated in the silica glass crucible 1. Therefore, the crucible evaluation unit 234 evaluates the ease of cracking of the silica glass crucible 1 based on the calculation result by the AE wave generation position calculation unit 233.

For example, when there are microcracks in the curved corner portion 13 and the bottom portion 12 of the silica glass crucible 1, when the silicon single crystal is actually pulled up using the silica glass crucible 1, the silica glass crucible 1 is broken in the middle. There is a strong fear. Therefore, the crucible evaluation unit 234 evaluates the easiness of cracking of the silica glass crucible 1 based on whether or not there is a curved corner portion 13 or bottom portion 12 or a connection portion microcrack between the corner portion 13 and the bottom portion 12. It is desirable to do.

The crucible evaluation unit 234 can be configured to evaluate the ease of cracking of the silica glass crucible 1 by combining a plurality of the above-exemplified methods. For example, the crucible evaluation unit 234 determines the target when the result of the measurement by the AE wave intensity measurement unit 231 is equal to or greater than a predetermined threshold value and more than a predetermined number of AE waves are measured. It can be evaluated that the silica glass crucible 1 is easily broken. Also, the crucible evaluation unit 234 may change the threshold value to be compared with the value of the measurement result obtained by the AE wave intensity measurement unit 231 according to the generation position of the AE wave, for example. Also, the crucible evaluation unit 234 may change the number of AE waves that are allowable for each location of the silica glass crucible 1. The crucible evaluating unit 234 may evaluate the ease of cracking of the silica glass crucible 1 by a combination other than those exemplified above.

<2-3-5. Measurement result storage unit 235>
The measurement result storage unit 235 is a storage device such as a semiconductor memory or a hard disk. The measurement result storage unit 235 stores the measurement, measurement, and calculation results obtained by the AE wave intensity measurement unit 231, the AE wave generation frequency measurement unit 232, and the AE wave generation position calculation unit 233. Further, the measurement result storage unit 235 stores the evaluation result obtained by the crucible evaluation unit 234. In the measurement result storage unit 235, for example, measurement, measurement, calculation result, and evaluation result for each silica glass crucible 1 are stored.

The above is an explanation of an example of the configuration of the crucible inspection apparatus 2.

<3. About external force ＞
The AE wave is generated by the generation or growth of cracks in the silica glass crucible 1 due to external force applied to the silica glass crucible 1 or internal force fluctuations. Therefore, in order to detect the AE wave by the crucible inspection apparatus 2, it is necessary to apply an external force to the silica glass crucible 1 or cause an internal force fluctuation.

In this embodiment, generation of AE waves is induced by applying an external force to the silica glass crucible 1 using air or water pressure. Specifically, for example, the compressed air is hit against the silica glass crucible 1 and the AE wave generated when the compressed air is hit is detected by the crucible inspection device 2. Further, for example, the crucible inspection apparatus 2 detects an AE wave generated using water pressure. By using air or water pressure in this way, AE waves can be induced non-destructively without destroying the silica glass crucible 1, and the ease of cracking of the silica glass crucible 1 can be inspected and evaluated.

In particular, the silica glass crucible 1 includes a cylindrical side wall part 11, a curved bottom part 12, and a container part that connects the side wall part 11 and the bottom part 12 and has a corner part 13 having a higher curvature than the bottom part 12. It has the shape of For this reason, the inside of the silica glass crucible 1 can be filled with water (liquid). By filling with water, an external force (force directed outward from the center inside the crucible) can be uniformly applied to the inner surfaces of the cylindrical side wall portion 11, the curved bottom portion 12, and the corner portion 13 having a predetermined curvature. it can.

Also, the position where the external force on the inner surface of the crucible is to be applied can be easily selected depending on the amount of water to be filled. For example, if only the bottom portion 12 is filled with water, an external force can be applied only to the bottom portion 12, and if water is filled up to the corner portion 13, an external force can be applied from the bottom portion 12 to the corner portion 13. Moreover, if water is filled to the predetermined height of the side wall part 11, external force can be given to the height with which the water of the bottom part 12, the corner part 13, and the side wall part 11 was filled.

Furthermore, if the AE wave is detected while filling with water, the AE wave can be inspected while continuously changing the position where the external force is applied to the inner surface of the crucible.

In general, when water is used as an external force application method in AE wave detection, an object is submerged in water. However, when the vessel-shaped silica glass crucible 1 is submerged in water, the pressure from the water is applied to the entire inner surface and outer surface of the silica glass crucible 1.
On the other hand, if the water is stored inside the silica glass crucible 1 so as to accumulate water, a uniform force can be applied only to the inner surface of the silica glass crucible 1. Thereby, variation in external pressure application can be suppressed, and highly accurate AE wave detection can be performed.
Moreover, by filling with water to a desired height or inspecting while filling, it is possible to select a method of applying external pressure suitable for inspection, and to improve the stability of AE wave detection.

In this way, by using the unique shape of the silica glass crucible 1 and filling the inside with water, it is necessary to apply an external force to the AE wave inspection. Can be performed stably.

In addition, the use of the crucible inspection apparatus 2 is not limited to the case of inspecting the silica glass crucible 1 nondestructively. For example, the crucible inspection apparatus 2 may be configured to detect an AE wave generated by a destructive inspection of the silica glass crucible 1.

<4. Operation of crucible inspection apparatus 2>
Next, an example of a crucible inspection method using the crucible inspection apparatus 2 will be described with reference to FIG. The AE sensor 21 of the crucible inspection apparatus 2 in the present embodiment is installed on the surface of the silica glass crucible 1. Specifically, the AE sensor 21 is installed on the inner surface of the silica glass crucible 1, for example. Then, an AE wave is generated in the silica glass crucible 1 by applying a predetermined external force to the silica glass crucible 1.

Referring to FIG. 9, the AE sensor 21 of the crucible inspection apparatus 2 detects an AE wave generated when a predetermined external force is applied to the silica glass crucible 1 (step S001). Specifically, the AE sensor 21 detects an AE wave and generates an AE signal according to the AE wave. The AE signal generated by the AE sensor 21 is amplified by the amplifier 22, and the amplified AE signal is received by the AE wave analyzer 23.

The AE wave analyzer 23 evaluates the ease of cracking of the silica glass crucible 1 based on the received AE signal (step S002). Specifically, the AE wave intensity measurement unit 231 of the AE wave analyzer 23 measures the intensity of the AE wave based on the received AE signal. In addition, the AE wave generation frequency measurement unit 232 of the AE wave analyzer 23 measures the number of AE wave generations based on the received AE signal. Further, the AE wave generation position calculation unit 233 of the AE wave analysis device 23 calculates the generation position of the AE wave. Then, the crucible evaluation unit 234 of the AE wave analysis device 23 uses the silica glass based on the measurement, measurement, and calculation results of the AE wave intensity measurement unit 231, the AE wave generation frequency measurement unit 232, and the AE wave generation position calculation unit 233. The ease of cracking of the crucible 1 is evaluated.

The above is an explanation of an example of the operation of the crucible inspection apparatus 2.

<5. Configuration / Function / Effect>
As described above, the crucible inspection apparatus 2 in the present embodiment includes the AE sensor 21 and the AE wave analysis apparatus 23. With such a configuration, the crucible inspection apparatus 2 can detect an AE wave generated when an external force is applied to the silica glass crucible 1. As a result, the crucible inspection apparatus 2 can evaluate the ease of cracking of the silica glass crucible 1 based on the detection result.
Further, the ease of extension of microcracks can be evaluated from the number of times the AE wave is detected. It is possible to evaluate whether or not it affects the cracking and deformation of the crucible from the ease of extension of microcracks.
The size of the microcrack can be estimated from the strength of the AE wave. It can be evaluated whether the size of the microcrack affects the cracking and deformation of the crucible.
The position of the microcrack can be estimated from the generation position of the AE wave. Considering the position where the pressure is applied by filling the raw material in the crucible and the position of the liquid surface during the pulling of the silicon single crystal, it can be evaluated whether the position where the microcracks are present affects the cracking and deformation of the crucible.
Further, by evaluating these in combination, it is possible to grasp the ease of extension, size, and position of the microcracks in the crucible. Thereby, it is possible to evaluate whether the microcrack affects the crucible crack and the deformation during the pulling in consideration of the pulling condition of the silicon single crystal (the length of pulling time, the raw material filling amount, etc.).

<6. Other configurations>
In the present embodiment, the AE sensor 21 includes the piezoelectric element 211, the receiving plate 212, and the connector 213. However, the configuration of the AE sensor 21 is not limited to the above case. For example, the AE sensor 21 may have a damper material.

In the present embodiment, the AE sensor 21 is installed on the inner surface of the silica glass crucible 1. However, the AE sensor 21 may be installed on a surface other than the inner surface such as the outer surface of the silica glass crucible 1.

In addition, as a process for manufacturing the silica glass crucible 1 (a method for manufacturing the silica glass crucible 1), a crucible inspection method using the crucible inspection apparatus 2 described in the present embodiment can be performed. By producing the silica glass crucible 1 in this way, it is possible to inspect whether or not an AE wave generation source such as a crack exists in the produced silica glass crucible 1. As a result, for example, the silica glass crucible 1 in which the number of defects such as cracks that generate AE waves when an external force is applied is equal to or less than a predetermined threshold value can be realized. Further, it is possible to realize the silica glass crucible 1 in which the strength of the AE wave generated when an external force is applied is equal to or less than a predetermined threshold value. Further, by using the silica glass crucible 1 manufactured by the method for manufacturing the silica glass crucible 1 described above, for example, by pulling up the silicon ingot by the Czochralski method, cracks are not generated during the pulling. Can raise the silicon ingot.

<Method for producing silicon single crystal>
FIGS. 10A to 10C are schematic views for explaining a method for producing a silicon single crystal using the silica glass crucible according to the present embodiment.
As shown in FIG. 10A, when pulling up the silicon single crystal, the silica glass crucible 1 is filled with polycrystalline silicon, and in this state, the polycrystalline silicon is heated by a heater disposed around the silica glass crucible 1. And melt. Thereby, the silicon melt 230 is obtained. At this time, by using the silica glass crucible of the present invention, the crucible during filling can be prevented from being damaged.

The volume of the silicon melt 230 is determined by the mass of polycrystalline silicon. Therefore, the initial height position H 0 of the liquid surface 23 a of the silicon melt 230 is determined by the mass of the polycrystalline silicon and the three-dimensional shape of the inner surface of the silica glass crucible 1. That is, when the three-dimensional shape of the inner surface of the silica glass crucible 1 is determined, the volume up to an arbitrary height position of the silica glass crucible 1 is specified, whereby the initial height of the liquid surface 23a of the silicon melt 230 is determined. The position H0 is determined.

After the initial height position H0 of the liquid surface 23a of the silicon melt 230 is determined, the tip of the seed crystal 24 is lowered to the height position H0 and brought into contact with the silicon melt 230. Then, the silicon single crystal 25 is grown by slowly pulling up the wire cable 561 while rotating it. At this time, the silica glass crucible 1 is rotated opposite to the rotation of the wire cable 561.

As shown in FIG. 10B, when the liquid surface 23 a is located on the side wall portion 11 of the silica glass crucible 1 when the straight body portion (the portion having a constant diameter) of the silicon single crystal 25 is pulled up. In this case, if the liquid surface 23a is pulled up at a constant speed, the descending speed Vm of the liquid surface 23a becomes almost constant, so that the pulling up is easily controlled.

However, as shown in FIG. 10 (c), when the liquid level 23a reaches the corner 13 of the silica glass crucible 1, the area rapidly decreases as the liquid level 23a descends. The speed Vm increases rapidly. The descending speed Vm depends on the inner surface shape of the corner portion 13.

By accurately measuring the three-dimensional shape of the inner surface of the silica glass crucible 1, the inner surface shape of the corner portion 13 can be known, and therefore how the descent speed Vm changes can be accurately predicted. it can. Based on this prediction, pulling conditions such as the pulling speed of the silicon single crystal 25 are determined. At this time, by using the silica glass crucible 1 of the present embodiment, since the deformation from the predicted shape is less, the prediction accuracy of the descent speed Vm is further improved. As a result, it is possible to prevent transition from occurring in the corner portion 13 and to automate the lifting.

In the method for producing a silicon single crystal according to the present embodiment, since the silica glass crucible 1 is prevented from being deformed by the heating of the silica glass crucible 1 when the silicon single crystal 25 is pulled up (such as falling of the side wall 11, distortion, rising of the bottom 12). The deviation of the descending speed Vm of the liquid surface 23a obtained from the three-dimensional shape of the inner surface of the glass crucible 1 is suppressed, and the silicon single crystal 25 having a high crystallization rate can be manufactured with a high yield. The silicon single crystal is pulled up in an argon atmosphere and under reduced pressure (about 660 Pa to 13 kPa).

<Silicon single crystal ingot>
A silicon ingot may be manufactured by setting the silica glass crucible 1 manufactured in the present embodiment to a pulling device and pulling up the silicon single crystal.
FIG. 11 is a schematic view illustrating a silicon single crystal silicon ingot.
The silicon single crystal ingot 600 is manufactured by setting the silica glass crucible 1 of the present invention in a pulling apparatus and pulling it up by the above-described silicon single crystal manufacturing method.

The ingot 600 has a shoulder 610 on the seed crystal 24 side, a straight body 620 continuous from the shoulder 610, and a tail 630 continuous from the straight body 620. Note that the seed crystal 24 is removed from the ingot 600. The diameter of the shoulder portion 610 gradually increases from the seed crystal 24 side to the straight body portion 620. The diameter of the straight body 620 is substantially constant. The diameter of the tail 630 gradually decreases as the distance from the straight body 620 increases.

The quality of the ingot 600 is closely related to the quality of the silica glass crucible 1 to be pulled up. For example, contamination of the silica glass crucible 1 (for example, an impurity metal element in the glass) or foreign matters leads to dislocation of the silicon single crystal in the ingot 600. Further, depending on the smoothness of the inner surface of the silica glass crucible 1 (unevenness that can be seen visually), the amount and size of bubbles in the vicinity of the surface, there is a minute amount into the silicon due to chipping of the crucible surface, cracking of the bubbles, or crushing. When debris (particles peeled off from the crucible) falls into the silicon melt, this mixes in the ingot and leads to dislocation.

In addition, the quality of the ingot 600 greatly depends on the pulling control in manufacturing the ingot 600. Below, the specific example of the relationship between the quality of the ingot 600 and raising control is demonstrated.
FIGS. 12A to 12C are schematic diagrams for explaining the pull-up control.
As shown in FIG. 12A, when the growth rate of the silicon single crystal is Vg, the pulling rate of the silicon single crystal is V, the lowering rate of the silicon melt is Vm, and the rising rate of the crucible is C. The following relationship holds.
Vg = V + Vm-C

Among these, the liquid level lowering speed Vm is determined by a function f of the crucible inner volume and the silicon single crystal growth speed Vg (see FIG. 12B). In the conventional technique, the liquid level lowering speed Vm is obtained by calculation using this function f. Further, since the pulling speed V and the crucible rising speed C are known as the conditions of the pulling apparatus, the silicon single crystal growth speed Vg = V + Vm−C is obtained therefrom.

However, in actual pulling, the inner shape of the crucible is deformed and the internal volume is changed due to exposure to high temperature (see FIG. 12C). In the pulling device, the silica glass crucible is inserted into the carbon susceptor. Therefore, the outer peripheral surface of the silica glass crucible is in a state of being fitted to the carbon susceptor. For this reason, the silica glass crucible is not deformed outward but deformed only inward. If the internal volume of the crucible changes, the calculation of the liquid level lowering speed Vm becomes inaccurate, and the silicon single crystal growth speed Vg cannot be determined accurately. This growth rate Vg is an important factor in the generation of crystal defects. Therefore, if the growth rate Vg cannot be accurately controlled, the quality of the ingot 600 is greatly affected.

If the inner radius of the crucible at the position of the silicon melt liquid surface is R, the diameter of the silicon single crystal (ingot) is r, the density of the silicon melt is ρL, and the density of the silicon single crystal is ρs, the liquid surface is in the crucible straight body. In some cases, the following equation holds:
Vg = ρL / ρs · (R / r) ² · Vm
Vg / Vm = ρL / ρs · (R / r) ² = k

When the variation rate of the inner radius of the crucible is α, the following equation is established.
Vg = ρL / ρs · (αR / r) ² · Vm
Vg = α ² · {ρL / ρs · (αR / r) ² · Vm}

Therefore, the square of α contributes to the deviation of Vg. Therefore, if R varies by 1%, Vg varies by about 2%.

Assuming that R = 0.797 m, r = 0.3 m, ρL = 2570 kg / m ³ , and ρs = 2300 kg / m ³ , k = 7.95 and 1 / k = 0.126.
For example, when a silicon single crystal (ingot) corresponding to a thickness of 1 mm of a silicon wafer is manufactured, the drop in the silicon melt level is 0.126 mm. Considering the cutting width (width of a blade or the like) when cutting a silicon wafer from an ingot and polishing after cutting, the thickness of the silicon wafer is about 700 μm to 800 μm. In order to make the COP substantially zero no matter where the ingot is cut, it is necessary to make the COP substantially zero in the entire area of the straight body portion of the ingot. In addition, when the structure portion falls within the range of 1/10 to 1/100 or less of the thickness of the silicon wafer, such as a semiconductor device having a three-dimensional structure to be described later, the thickness of the silicon wafer is 1 A pulling control of / 10 to 1/100 or less (pulling control for making COP substantially zero) is necessary. In this case, in order to control the decrease in the liquid level of the silicon melt, it is necessary to control the accuracy of 0.01 mm or less.

Thus, when the inner diameter of the silica glass crucible 1 fluctuates 1%, the growth rate Vg of the silicon single crystal fluctuates 2%. Further, the rate of decrease Vm of the silicon melt at the corner 13 of the silica glass crucible 1 is higher than the rate of decrease of the level of the silicon melt at the straight body of the silica glass crucible 1. Therefore, the influence of the variation in the inner diameter of the crucible on the variation in the liquid level is larger in the corner portion 13 than in the straight body portion of the crucible.

In this embodiment, since the internal residual stress in the thickness direction of the silica glass crucible 1 actually used for pulling can be measured accurately, the relationship between the internal residual stress and the change in the inner diameter of the crucible after use (in terms of operation results) Based on the simulation of the fluctuation amount of the inner diameter of the crucible based on this, the inner diameter fluctuation amount of the crucible in use can be estimated at the stage of the silica glass crucible 1 before use (before the silicon single crystal is pulled up). This makes it possible to reduce the deviation from the target value of the growth rate Vg of the silicon single crystal compared to the case where the deformation of the crucible is not considered at all as in the conventional technique, and the entire length of the straight body portion 620 of the ingot 600 can be reduced. Defects can be suppressed (substantially zero).

FIG. 13 is a diagram showing a variation amount of the inner diameter of the crucible.
In FIG. 13, the horizontal axis indicates the amount of variation in the inner diameter of the crucible, and the vertical axis indicates the height from the bottom of the crucible.
The plot of FIG. 13 is a measured value. Moreover, the line L connects the average of the measured value in each height.
As shown by line L, it can be seen that fluctuations in the inner diameter of the crucible (that is, fluctuations in the crucible internal volume) occur on average. As in this embodiment, if the rising speed A of the silicon single crystal is changed based on the shape of the inner surface of the crucible, it is possible to control the growth rate Vg of the silicon single crystal so that the entire length of the silicon single crystal is within a defect-free range. become.
On the other hand, in the prior art, feedback control during CZ single crystal growth is performed only by a combination of ADC (automatic diameter control) and liquid level control. That is, in the prior art, the shape of the crucible in actual use is not taken into consideration at all, and the shape change of the crucible cannot be accurately grasped, so that the growth rate Vg is accurately controlled in pulling up the silicon single crystal. I can't. In other words, the conventional technology does not correspond to the Vg control corresponding to the accuracy of the liquid level lowering velocity Vm of 0.01 mm or less as described above, and the performance of the semiconductor device, particularly the device of the three-dimensional structure is sufficient. It is not a silica glass crucible that can produce a silicon single crystal (ingot) to be drawn out.

Here, it is possible to estimate the behavior of the crucible from the production history, inspection results, and use results of the crucible so far by simulation technology (example of crucible behavior). From this, the following can be understood about the deformation of the crucible.
(1) The amount of fluctuation is large in the thin part.
(2) The amount of deformation increases as the weight of the crucible increases.
(3) The amount of deformation of the inner surface increases as the crucible has a smaller outer diameter.
(4) The amount of deformation in the eccentric part is large.
(5) The crucible is likely to be deformed at a non-symmetrical portion of the carbon susceptor.
(6) The silica glass crucible is also ceramic, and the inner peripheral surface of the crucible is not a perfect circle.

As described above, in order to control the growth rate Vg of the silicon single crystal by Vg = V + Vm−C, it is necessary to accurately grasp the crucible information. Therefore, it is desirable to record all crucible information from the past in association with each other so that they can be searched.

It is also important to regulate the relationship between the growth rate (Vg) of the silicon single crystal and the temperature gradient (G) in the pulling axis direction near the solid-liquid interface in order to suppress the occurrence of crystal defects in the ingot 600. Become. Here, the temperature gradient (G) in the pulling axis direction is higher on the melt side than on the solid side (in other words, lower on the solid side than on the melt side). In addition, the temperature gradient in the plane (in the radial direction) perpendicular to the pulling axis (in the radial plane) is constant.

The silica glass crucible 1 of the present invention can stabilize the height H between the liquid surface of the silicon melt and the tip of the heat shielding member because the deformation and collapse of the silicon single crystal are suppressed. In the ingot 600 obtained by pulling up the silicon single crystal using such a silica glass crucible 1, the crystal defects in the straight body portion 620 are substantially zero. For example, COP (Crystal Originated Particle) in the straight body 620 is substantially zero. COP is one of crystal defects and is a fine defect in which silicon atoms are not present at lattice points of a single crystal (holes are collected). The presence of the COP causes deterioration of electrical characteristics (leakage current, resistance value distribution, carrier mobility, etc.) of the semiconductor device.

Here, generation of COP will be described.
FIG. 14 is a schematic diagram for explaining a situation in which various defects occur based on the Boronkov theory.
As shown in FIG. 14, in the Boronkov theory, when the pulling speed is V (mm / min) and the temperature gradient in the pulling axis direction in the vicinity of the solid-liquid interface of the ingot (silicon single crystal) is G (° C./mm), The relationship between V / G and point defect concentration is schematically shown with the ratio V / G being the horizontal axis and the concentration of vacancy type point defects and the concentration of interstitial silicon type point defects being the same vertical axis. expressing. It is shown that there is a critical point that becomes a boundary between a region where a vacancy type point defect occurs and a region where an interstitial silicon type point defect occurs.

When V / G falls below the critical point, a single crystal having a dominant interstitial silicon type point defect concentration is grown. In a range where V / G is less than the critical point (V / G) I, the interstitial silicon type point defects are dominant in the single crystal, and the region where the aggregate of interstitial silicon point defects exists [I ] Appears.

On the other hand, when V / G exceeds the critical point, a single crystal having a dominant vacancy point defect concentration is grown. In a range where V / G is greater than the critical point (V / G) v, a region where vacancy type point defects are dominant in the single crystal and agglomerates of vacancy type point defects exist [V] Appears and COP occurs.

FIG. 15 is a schematic diagram showing the relationship between the pulling rate and the defect distribution during single crystal growth.
The defect distribution shown in FIG. 15 is obtained by growing a silicon single crystal while gradually lowering the pulling speed V, cutting the grown single crystal along the central axis (pickup axis) to form a plate-like specimen, It shows the occurrence of defects. The defect distribution is a result of evaluating the occurrence of defects by decorating Cu on the surface of the plate-shaped specimen and performing heat treatment, then observing the plate-shaped specimen by the X-ray topograph method.

As shown in FIG. 15, when the growth is performed at a high pulling speed, the region [VOP] where vacancy-type point defect aggregates (COP) exist over the entire in-plane region perpendicular to the pulling axis direction of the single crystal [V ] Occurs. When the pulling speed is decreased, the OSF region appears in a ring shape from the outer peripheral portion of the single crystal. The diameter of the OSF region gradually decreases as the pulling speed decreases, and disappears when the pulling speed becomes V1. Accordingly, a defect-free region [P] (region [PV]) appears instead of the OSF region, and the entire in-plane area of the single crystal is occupied by the defect-free region [P]. When the pulling rate is reduced to V ₂ , a region [I] where interstitial silicon-type point defect aggregates (LD) are present appears, and finally appears in a defect-free region [P] (region [PI]). Instead, the entire in-plane area of the single crystal is occupied by the region [I].

In the present embodiment, the fact that the COP shown above is substantially zero means that the number of detected COPs is substantially zero. COP is detected by a particle counter. In the particle counter, when the number of particles of 0.020 μm or more is detected only 30 or less on the wafer surface (semiconductor device forming surface), the number is substantially zero. In this specification, “0.020 μm COP” means, for example, 0.020 μm when measured with the SP series manufactured by Tencor or the particle counter device for semiconductors and silicon wafers having the same performance as this device. A COP detected as a particle size.

As described above, the ingot 600 in which the COP of the straight body 620 is substantially zero is sliced into, for example, a diameter of 300 mm and a thickness of about 1 mm to become a silicon wafer. In a semiconductor device manufactured using a silicon wafer cut out from the ingot 600, electrical characteristics can be stabilized and deterioration can be suppressed.

Note that the method of detecting COP may be other than the particle counter. For example, a method using a surface defect inspection apparatus, after forming an oxide film of a predetermined thickness on the surface of a wafer, applying an external voltage to destroy the oxide film at the defective portion of the wafer surface and deposit copper, Examples include a method of detecting defects (COP) by observing the deposited copper with the naked eye, a transmission electron microscope (TEM), a scanning electron microscope (SEM), and the like. In the straight body 620 of the ingot 600, COP is not detected by such a detection method (substantially becomes zero).

A more preferable form of the ingot 600 according to the present invention is that all the straight body portions 620 do not have a region where point defects (voids) called vacancy are aggregated (V-Rich region where COP exists), and OSF (Oxidation Induced Stacking). Fault) is not detected, and there is no region (I-Rich region) where interstitial point defects called interstitials exist, that is, all of the straight body portion 620 is a neutral region. Here, the neutral region includes not only a region having no defects, but also a region that does not exist as an agglomerated defect or is so small that it cannot be detected even if a slight vacancy or interstitial is included.

Thus, since the crystal defects in the straight body portion 620 are zero, the electrical characteristics of the semiconductor device manufactured using the wafer cut out from the ingot 600 can be stabilized and the deterioration can be suppressed.

<Homoepitaxial wafer>
Further, a homoepitaxial wafer (hereinafter, also simply referred to as “epitaxial wafer”) may be configured by using a wafer cut out from the ingot 600 as a substrate portion. FIG. 16 is a schematic cross-sectional view illustrating an epitaxial wafer. The epitaxial wafer 700 includes a wafer substrate portion 710 cut out from the ingot 600, and a silicon single crystal epitaxial layer 720 provided on the substrate portion 710. In this embodiment, the epitaxial layer 720 is a silicon homoepitaxial layer. The thickness of the epitaxial layer 720 is about 0.5 μm to 20 μm.

An example of the manufacturing method of the epitaxial wafer 700 is shown. First, the substrate unit 710 is heated to about 1200 ° C. in an epitaxial furnace. Next, vaporized silicon tetrachloride (SiCl ₄ ) and trichlorosilane (trichlorosilane, SiHCl ₃ ) are flowed into the furnace. Thus, a silicon single crystal film is vapor-phase grown (epitaxial growth) on the surface of the substrate portion 710, and an epitaxial layer 720 is formed.

By forming the epitaxial wafer 700 using a wafer cut out from the ingot 600 having substantially zero crystal defects, the epitaxial layer 720 having substantially zero crystal defects can be formed.

In recent years, miniaturization of semiconductor integrated circuits has progressed, and the limits of conventional planar transistors are approaching. Therefore, a transistor called a Fin-type FET (fin-type field effect transistor) structure has been proposed (see, for example, Patent Documents 11 and 12).
In the conventional planar type, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) structure is formed inside the silicon wafer surface.
In the planar type, the source and drain are two-dimensionally configured. However, the Fin-type FET has a channel region called FIN in the upper layer of the silicon surface and is in contact with the silicon wafer to form a three-dimensional MOSFET.
The planar type has been miniaturized by the gate length, but in the Fin type FET, the fin width is managed as the minimum dimension. There is also a Fin type FET having a fin width of about 20 nm, that is, about the same as COP.
Therefore, it is required to reduce the size of the COP to the limit as the surface quality of the silicon wafer directly under the fin.
Such a three-dimensional structure is adopted not only in a Fin type FET but also in a three-dimensional NAND type flash memory.
In order to manufacture such a semiconductor device, a homoepitaxial wafer with improved quality is desired.
When forming a homoepitaxial layer using a silicon wafer, the size of the COP of the silicon wafer needs to be smaller and smaller. Although there is a heat treatment method to suppress COP on the silicon wafer, it is important to control the silicon melt at the time of pulling in order to make COP substantially zero at the ingot stage of the silicon single crystal. is there. The inventors of the present application have found that the silicon melt can be controlled by paying attention to the relationship between the liquid level fluctuation of the silicon melt and the silica glass crucible.

In the present embodiment, the silica glass crucible can be evaluated based on the detection result of the AE wave, and a crucible in which there is no microcrack that affects cracking or deformation during pulling can be selected. When microcracks exist in the silica glass crucible, the crucible is likely to be deformed at a high temperature for a long time during the pulling of the silicon single crystal. If the silica glass crucible is deformed during the pulling of the silicon single crystal, the surface of the silicon melt is disturbed, and various pulling conditions such as the pulling speed cannot be controlled. By pulling up a silicon single crystal using a crucible that does not have microcracks that affect cracking and deformation during pulling, it becomes possible to control conditions such as the pulling speed during pulling with high precision, thereby eliminating crystal defects. It becomes possible to produce an ingot that is substantially zero. Moreover, a high quality epitaxial wafer can be provided by forming an epitaxial layer on the substrate portion of the wafer using the ingot.

The epitaxial layer 720 may be formed on the entire surface of the substrate portion 710 or may be partially formed. As a result, it is possible to provide a high-quality epitaxial wafer 700 that can be used when crystal integrity is required or when a multilayer structure with different resistivity is required.

<Process from crucible manufacturing to silicon single crystal product manufacturing>
FIG. 17 is a flowchart illustrating the steps from crucible manufacturing to wafer manufacturing.
Steps S201 to S206 shown in FIG. 17 are crucible manufacturing processes, steps S207 to S214 are ingot manufacturing processes, steps S215 to S221 are silicon wafer manufacturing processes, and steps S222 to S227 are the same. It is a manufacturing process of an epitaxial wafer.

A series of processes from crucible production to ingot production shown in steps S201 to S214 is referred to as a crucible-ingot production process.
A series of processes from crucible manufacturing to silicon wafer manufacturing shown in steps S201 to S221 is referred to as a crucible-silicon wafer manufacturing process.
A series of processes from crucible manufacturing to epitaxial wafer manufacturing shown in steps S201 to S227 is referred to as a crucible-epiwafer manufacturing process.

In order to perform consistent manufacturing condition control and quality control in each of the crucible-ingot manufacturing process, the crucible-silicon wafer manufacturing process, and the crucible-epi wafer manufacturing process, in this embodiment, there is an integrated control system that collectively manages each process. Used.

In this embodiment, an integrated control system is used for production management that assumes the quality of silicon single crystal products (ingots, silicon wafers, epitaxial wafers) due to crucible manufacturing.

Conventionally, for example, when an ingot is manufactured by pulling up a silicon single crystal, the diameter of the straight body portion is controlled to be constant by ADC (automatic diameter control). The time required for pulling up the straight body having a diameter of about 300 mm to a total length of 2000 mm is about 4000 minutes as 0.5 mm / min. In addition, as a whole in the production of silicon ingots, (1) an operation of carefully loading the silica glass crucible so that the silica glass crucible does not break when filling the silica glass crucible, (2) melting of the polycrystalline silicon, (3) Dash necking (dislocation removal) process, (4) forming the shoulder of the silicon ingot, (5) lifting the total length of the straight body part to 2000 mm, (6) tail tailing to prevent dislocation from entering the silicon ingot, (7) The furnace is cooled and the silicon ingot is recovered. In order to manufacture a single silicon ingot having a diameter of 300 mm and a total length of 2000 mm by performing such a series of processes, it takes about 7 days.

The control during this period is mainly based on the relationship between the lifting speed and the weight, and the aim is to raise the COP free over the entire length of the straight body with a constant diameter. The height H between the surface of the silicon melt important for pulling and the cone portion 571 is high when the pulling speed is high, and is low when the pulling speed is slow. Conventionally, the height H is controlled based on the individual difference for each lifting device and the experience of the operator.

In the present embodiment, the height H at the time of pulling up can be controlled more uniformly by predicting the amount of inner surface deformation of the crucible. That is, in the pulling device, the crucible is housed in the carbon susceptor 520, and becomes a weight of, for example, 500 kg due to the filling of polycrystalline silicon. In addition, the crucible being pulled becomes a high temperature of about 1600 ° C. and is pushed outward by the silicon melt, and the gap with the carbon susceptor 520 disappears. Since the carbon susceptor 520 is not deformed, as a result, the crucible is easily deformed inward by a reaction force from the carbon susceptor 520.

The integrated control system of the present embodiment accumulates information such as the manufacturing history of the crucible used so far, the measurement result of the internal residual stress before use, the shape change after use, etc. Calculate the behavior and deformation of the crucible when it is pulled up before use. Thereby, the deformation | transformation of the crucible internal volume can be known from the deformation | transformation of the crucible during raising to be estimated, and the height H during raising can be strictly controlled. Therefore, it is possible to perform consistent control to manufacture an ingot in which crystal defects are substantially zero, manufacture a silicon wafer from the ingot, and manufacture an epitaxial wafer using the silicon wafer.

[Example]
(Production example)
A silica glass crucible was manufactured based on the rotational molding method. Specifically, silica powder having an average thickness of 15 mm was deposited on the inner surface of a 32-inch rotating mold to form a silica powder layer, and arc discharge was performed with three electrodes of three-phase alternating current. In the arc melting step, the energization time was 90 minutes, the output was 2500 kVA, and the silica powder layer was evacuated for 10 minutes from the start of energization. Eight silica glass crucibles were produced by the method as described above.

(Inspection example 1)
Of the inner surface of the manufactured silica glass crucible, three AE sensors 21 are applied to the respective predetermined portions of the side wall portion, corner portion, and bottom portion, and the manufactured silica glass crucible is filled with water to fill the inner surface of the crucible. The external force was given toward. The resulting AE wave was measured by each AE sensor 21.

Test conditions and measurement conditions are shown below.
(A) Measurement conditions (a-1) Test machine crosshead speed: 3 mm / sec (a-2) Target load: 500 Newton (N)
(B) Measurement conditions (b-1) Preamplifier gain: 40 dB (dB)
(B-2) Filter: 20 to 400 kHz bandpass filter (b-3) Load analog signal: 500 N / V

FIG. 18 is a diagram showing the relationship between the number of AE wave generations and the maximum energy value.
FIG. 18 shows the result of detecting AE waves for the eight manufactured silica glass crucibles according to the test conditions and measurement conditions. The horizontal axis represents the number of AE waves generated (pieces / cm ² ), and the vertical axis represents the maximum energy value (dBs) of the AE waves.

Moreover, after measuring with the AE sensor 21, the silicon single crystal was pulled up using the silica glass crucible, and the presence or absence of cracking of the silica glass crucible was inspected.
The silica glass crucible shown by the circled plots in FIG. 18 is not cracked. On the other hand, cracks occurred in the silica glass crucible indicated by the triangular plot in FIG.
For this reason, the threshold for the number of AE waves generated was set to 6 / cm ^2, and the threshold for the maximum energy value of the AE waves was set to 10 dBs.

Next, five other silica glass crucibles were manufactured by the same manufacturing method as the above eight silica glass crucibles. About these five silica glass crucibles, AE waves at the side wall, corner and bottom are measured, and the silica glass crucible after pulling up the above-mentioned threshold of the number of AE waves generated, the threshold of the maximum energy value, and the silicon single crystal. The relationship between the presence or absence of cracks was investigated. Hereinafter, the relationship between the measurement results and the cracking of the silica glass crucible was as follows.

From the above, it can be seen from the result of AE wave measurement that the silica glass crucible is easily broken when the number of AE waves generated and the threshold value of the maximum energy value are exceeded at any of the side wall, corner and bottom. . Further, from the result of AE wave measurement, it is understood that the silica glass crucible is not broken when the number of AE waves generated and the threshold value of the maximum energy value are not exceeded in any of the side wall part, the corner part and the bottom part.

Although the present invention has been described with reference to the above embodiment, the present invention is not limited to the above-described embodiment. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

Note that the present invention enjoys the benefit of the priority claim based on the patent application of Japanese Patent Application No. 2015-254651 filed on December 25, 2015 in Japan, and is described in the patent application. The contents are all included in this specification.

DESCRIPTION OF SYMBOLS 1 Silica glass crucible 11 Side wall part 12 Bottom part 13 Corner part 111 Transparent layer 112 Bubble containing layer 2 Crucible inspection apparatus 21 AE sensor 211 Piezoelectric element 212 Receiver plate 213 Connector 22 Amplifier 23 AE wave analysis apparatus 231 AE wave intensity measurement part 232 AE Wave generation frequency measurement unit 233 AE wave generation position calculation unit 234 Crucible evaluation unit 235 Measurement result storage unit 3 Crack 600 Ingot 700 Epitaxial wafer

Claims

Inspecting the ease of cracking of a silica glass crucible comprising a cylindrical side wall, a curved bottom, and a corner provided between the side wall and the bottom and having a curvature higher than the curvature of the bottom. A crucible inspection device,
A crucible inspection apparatus having an AE wave detecting means installed on the surface of a silica glass crucible and detecting an AE (Acoustic Emission) wave generated when a predetermined external force is applied to the silica glass crucible.
The crucible inspection device according to claim 1,
The AE wave detecting means is a crucible inspection device installed on the inner surface of a silica glass crucible.
The crucible inspection device according to claim 1 or 2,
Having at least three AE wave detection means;
A crucible inspection apparatus comprising position specifying means for specifying an AE wave generation position based on detection results from a plurality of the AE wave detecting means.
A crucible inspection apparatus according to any one of claims 1 to 3,
A crucible inspection apparatus having a crucible evaluation means for evaluating the ease of cracking of a silica glass crucible based on the detection result of the AE wave detection means.
The crucible inspection device according to claim 4,
The crucible evaluation unit is a crucible inspection device that evaluates the fragility of the silica glass crucible based on the number of times the AE wave detection unit detects the AE wave.
The crucible inspection device according to claim 4 or 5,
The crucible evaluation unit is a crucible inspection device that evaluates the fragility of the silica glass crucible based on the intensity of the AE wave detected by the AE wave detection unit.
The crucible inspection apparatus according to any one of claims 4 to 6,
The crucible evaluation unit is a crucible inspection device that evaluates the fragility of the silica glass crucible based on the AE wave generation position specified by the position specifying unit.
The crucible evaluation means is a crucible inspection apparatus that evaluates the ease of cracking of a silica glass crucible by combining at least two of the methods described in any one of claims 5 to 7.
A crucible inspection apparatus according to any one of claims 1 to 8,
The said AE wave detection means is a crucible inspection apparatus which detects the AE wave which arises when compressed air is collided with a silica glass crucible.
The crucible inspection apparatus according to any one of claims 1 to 9,
The said AE wave detection means is a crucible inspection apparatus which detects the AE wave produced using the water pressure to the crucible inner surface by the water with which the said silica glass crucible was filled.
Inspecting the ease of cracking of a silica glass crucible comprising a cylindrical side wall, a curved bottom, and a corner provided between the side wall and the bottom and having a curvature higher than the curvature of the bottom. A crucible inspection method,
A crucible inspection method for detecting an AE (Acoustic Emission) wave that is set on the surface of a silica glass crucible and is generated when a predetermined external force is applied to the silica glass crucible.
A cylindrical side wall portion, a curved bottom portion, and a corner portion provided between the side wall portion and the bottom portion and having a curvature higher than the curvature of the bottom portion, and when an external force is applied, an AE wave A silica glass crucible in which the number of defects that yields is less than or equal to a predetermined threshold.
A method for producing a silica glass crucible comprising a cylindrical side wall part, a curved bottom part, and a corner part provided between the side wall part and the bottom part and having a curvature higher than the curvature of the bottom part,
An AE wave inspection means for inspecting the AE wave is installed on the surface of the silica glass crucible, a predetermined external force is applied to the silica glass crucible, and an AE (Acoustic Emission) wave generated when the predetermined external force is applied to the silica glass crucible. The manufacturing method of the silica glass crucible which has the process to detect.
A method for producing a silicon ingot, comprising the step of pulling up a silicon single crystal using the silica glass crucible produced by the method for producing a silica glass crucible according to claim 13.
Forming a substrate portion by a wafer formed by cutting out a silicon ingot produced by the method according to claim 14;
Forming a silicon single crystal homoepitaxial layer on the substrate part.