WO2017158656A1

WO2017158656A1 - Silica glass crucible and method for producing silica glass crucible

Info

Publication number: WO2017158656A1
Application number: PCT/JP2016/001614
Authority: WO
Inventors: 俊明須藤; 忠広佐藤; 賢北原; 修司飛田; 江梨子北原
Original assignee: 株式会社Sumco
Priority date: 2016-03-18
Filing date: 2016-03-18
Publication date: 2017-09-21
Also published as: TW201738414A

Abstract

A method for producing a silica glass crucible to be produced using a rotational molding process, the method having a step for measuring the state of scattering at each location in the thickness direction of the silica glass crucible of a laser beam that is emitted into the silica glass crucible, which has a straight cylindrical body section having an opening at the upper end thereof, and also has a floor section formed at the lower end of the straight cylindrical body section. The silica glass crucible has a light-transmitting layer through which a laser beam emitted at the silica glass crucible is transmitted from the inner surface of the silica glass crucible to the outer surface thereof, and also has a light-scattering layer positioned on the outside of the light-transmitting layer. The thickness of the light-transmitting layer when measured on the basis of the state of scattering of the laser beam emitted at the silica glass crucible falls within a prescribed range around the entire circumference of the silica glass crucible at the edge thereof.

Description

Silica glass crucible and method for producing silica glass crucible

The present invention relates to a silica glass crucible and a method for producing a silica glass crucible.

Silica glass crucible used for silicon single crystal pulling, for example, by providing a transparent layer and a bubble-containing layer, etc., reduces the occurrence of brown ring during silicon single crystal pulling, and makes thermal control easier, The crystallinity of the silicon single crystal is improved.

During the pulling of the silicon single crystal, the silica glass crucible is exposed to a high temperature of about 1410 ° C. or higher, which is the melting temperature of silicon. When the bubble density in the bubble-containing layer is not uniform, for example, when the bubble-containing layer is composed of layers having a plurality of different bubble densities, the layers having different bubble densities have different coefficients of thermal expansion, so the silicon melting temperature is high. In the state, the forces experienced by the layers having different cell densities are different. Therefore, the silica glass crucible may be deformed or damaged depending on the shape of the silica glass crucible, the mass of the silicon solution, the time of exposure to high temperature, and the like.

On the other hand, for example, when the silica glass crucible is composed of a single layer in the thickness direction, the constituent atoms of the silica glass are connected to the thickness direction of the silica glass crucible in a network shape, and the same silica network is formed in the layer. It becomes a structure. Therefore, once a crack occurs in the silica glass crucible and the network-like bond is broken, the crack expands to a wide area of the crucible, and as a result, the silica glass crucible may break. On the other hand, when the silica glass crucible is composed of a plurality of transparent layers and bubble-containing layers in the thickness direction, or the silica glass crucible is composed of a plurality of transparent layers or bubble-containing layers in the thickness direction. In this case, since there are a plurality of interfaces in the thickness direction and the structure of the silica network is different from the boundary portion, the expansion of cracks stops at the interface portion.

As described above, since the layer structure in the thickness direction of the silica glass crucible has a great influence on the heat resistance and impact resistance, it is important to measure the layer structure. However, since silica glass is transparent, when the size of the bubbles is fine, these layer structures may not be sufficiently observed visually. Further, in the transparent layer, a defect such as a fine scratch may exist even if no abnormality is observed by visual inspection or the like.

These silica glass crucible layer structures and defects such as fine scratches may cause defects in the silicon ingot when exposed to silicon melt during the pulling of the silicon single crystal. It is important in the design and quality control of silica glass crucibles to measure defects such as fine scratches.

Since silica glass crucibles for pulling silicon single crystals are generally manufactured by a rotational mold method, it is difficult to control characteristics such as shape and interior. The manufactured silica glass crucible is subjected to the following measurement, but it is performed in a non-contact manner because it is necessary to keep the inner surface of the silica glass crucible clean.

The structure, defects, etc. of the layer in the thickness direction of the manufactured silica glass crucible have been confirmed by destructive inspection after extracting the manufactured silica glass crucible. In general, visual inspection uses transmitted light or the like as in the case of observing an object with an optical microscope or the like. For example, a silica glass crucible sliced on a line connecting a light source and an observation point is installed and irradiated with light, and the transmitted light of the silica glass crucible is visually or imaged to detect defects in the glass. .

Further, as a method for inspecting the silica glass crucible, an image is acquired in the depth direction of the silica glass crucible while changing the depth of focus of the optical camera described in Patent Document 1, and air bubbles in the silica glass crucible are inspected nondestructively. A technique for measuring the bubble content is known.

Furthermore, by obtaining the three-dimensional coordinates of the inner surface of the silica glass crucible described in Patent Document 2, and measuring the Raman spectrum of the inner surface of the silica glass crucible at a plurality of measurement points, the three-dimensional distribution of the Raman spectrum of the inner surface is obtained. Methods for determining are also known.

Furthermore, as disclosed in Patent Document 3, for example, ultraviolet light having a wavelength shorter than 365 nm is irradiated on the wall surface of the silica glass crucible, and the number of fluorescent spots of the generated light having a wavelength of 400 nm to 600 nm is measured. A method for detecting impurities localized in a silica glass crucible that causes generation of crystal defects or the like that occur during crystal pulling, and a laser beam described in Patent Document 4, and the impurity component from the wavelength and intensity of fluorescence generated by the incidence. And a method for detecting the impurity component contained in the extreme surface layer of the inner surface of the silica glass crucible by calculating the content of the impurity component.

However, in the visual inspection, when a layered structure is formed in the light transmission direction on the entire light transmission surface, the layer structure cannot be detected. Further, for example, when a defect or the like is very small, the intensity of diffracted light or the like by the defect is not sufficient, and the defect or the like may not be detected because it is hidden by transmitted light from a light source. Since the inspection methods described in Patent Documents 1 to 3 are methods for measuring the shape of the silica glass crucible and the state near the inner surface, the inside of the transparent layer or the bubble-containing layer in the thickness direction of the silica glass crucible that cannot be detected by visual inspection or the like A defect such as a further layer structure or a fine scratch in the transparent layer existing inside could not be detected.

JP 2012-116713 A JP 2013-133227 A Japanese Patent Laid-Open No. 3-146396 JP 2012-17243 A

An object of the present invention is to provide a technique for detecting a further layer structure or a defect or the like existing in a transparent layer or a bubble-containing layer that could not be detected conventionally, and the defect or the like is not detected. The object of the present invention is to provide a silica glass crucible having appropriate heat resistance characteristics and / or impact resistance characteristics.

The inventor enters laser light on the upper surface of the silica glass crucible or the inner surface near the upper end of the silica glass crucible, and observes scattered light at each position in the thickness direction inside the side wall of the silica glass crucible. The inventors have found that there are further layer structures, defects, etc. existing inside the transparent layer or bubble-containing layer that could not be detected by the conventional method, and invented a method that can be easily and non-destructively observed.

According to the present invention, the layer structure and defects inside the transparent layer or the bubble-containing layer can be observed by a nondestructive and simple method. In addition, in the production process of the silica glass crucible, by performing the inspection according to the present invention, the silica glass crucible having a certain type of defect can be identified, the defect or the like is not detected, and appropriate heat resistance characteristics or / Alternatively, a silica glass crucible having impact resistance characteristics can be obtained. Furthermore, by using the silica glass crucible that has undergone the manufacturing process, it is possible to reduce the occurrence of crystal defects in the silicon single crystal ingot due to the crucible defects.

It is a figure which shows an example of a structure of the crucible measuring apparatus concerning the 1st Embodiment of this invention. It is a figure which shows an example at the time of measuring the mode at the time of entering a laser beam into a silica glass crucible from an end surface direction. It is a figure which shows an example at the time of measuring the mode at the time of entering a laser beam into a silica glass crucible from an end surface direction. It is a figure which shows an example at the time of measuring the mode at the time of entering a laser beam into a silica glass crucible from an end surface direction. It is a flowchart which shows an example of the flow of the crucible measuring method concerning 1st Embodiment. It is a figure which shows an example of an actual measurement image. It is a figure which shows an example of an actual measurement image. It is a figure which shows an example of an actual measurement image. It is a figure which shows an example of an actual measurement image. It is a figure which shows the internal residual stress of the silica glass crucible shown in FIG. It is a figure which shows the internal residual stress of the silica glass crucible shown in FIG. It is a figure which shows an example of the scattering condition at the time of using a cross line laser. It is a figure which shows an example of the scattering condition at the time of using a cross line laser. It is a figure which shows an example of a structure of the crucible measuring apparatus concerning 2nd Embodiment. It is a flowchart which shows an example of the flow of the crucible measuring method concerning 2nd Embodiment. It is a figure which shows the influence which the distance of the inner surface of a crucible and an illumination part has on the measurement of a scattering condition. It is a figure which shows an example of a structure of the crucible measuring apparatus in 3rd Embodiment. It is a figure which shows an example of the position where the crucible measuring apparatus in 3rd Embodiment measures a Raman spectrum. It is a flowchart which shows an example of the flow of the crucible measuring method concerning 3rd Embodiment. It is an example of the Raman spectrum actually measured. It is an example of the Raman spectrum actually measured.

In this specification, the laser light scattering state refers to the state of spread and intensity of the laser scattered light. The light transmission layer is a transparent layer and refers to a region where no defect such as a scratch exists. A layer having defects such as scratches in the bubble-containing layer or the transparent layer is referred to as a light scattering layer.

The silica glass crucible in the present embodiment includes a cylindrical side wall portion (straight barrel portion) having an opening at the upper end, a curved bottom portion, a corner portion connecting the side wall portion and the bottom portion and having a larger curvature than the bottom portion. It has the shape provided with. Moreover, 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.

The silica glass crucible in the present embodiment is manufactured using, for example, a rotational mold method. The rotational mold method is a method for producing a silica glass crucible by depositing silica powder in a rotating mold (made of carbon) and arc melting the deposited silica powder layer. Since the shape in the vicinity of the opening end of the silica glass crucible is likely to be uneven, the opening end of the silica glass crucible by the rotational molding method is cut with a predetermined width to align the shape of the opening end.

The silicon single crystal is produced, for example, by rotating the silica glass crucible, melting polycrystalline silicon inside, bringing the seed crystal into contact with the silicon melt, and pulling up the seed crystal after necking treatment. Is done. In general, the silica glass crucible is used every time the silicon single crystal is pulled. That is, the silica glass crucible needs to be prepared separately for each pulling of the silicon single crystal.

As an example of the silica glass crucible, the ratio of the thickness of the bubble-containing layer to the thickness of the transparent layer is 0.7 in the middle portion between the upper end and the lower end of the portion formed in the vertical direction of the silica glass crucible. With the configuration of ~ 1.4, volume expansion due to heating can be minimized, and deformation and melting of the silica glass crucible can be reduced (Japanese Patent Laid-Open No. 2012-116713).

Moreover, by making a synthetic silica glass layer, a natural silica glass layer, an impurity-containing silica glass layer and a natural silica glass layer in the thickness direction from the inner surface to the outer surface of the silica glass crucible, the deformation and melting of the silica glass crucible can be prevented. It can be reduced (Japanese Patent Laid-Open No. 2012-6804).

Furthermore, the roundness of the inner surface of the crucible and the roundness of the outer surface of the crucible are both 0.4 or less with respect to the maximum thickness M at the same measurement height as the roundness. A high crystallization rate can be realized during crystal pulling (Japanese Patent Laid-Open No. 2009-286651).

As in the above document, silica glass crucibles having various structures are known. The silica glass crucible is provided with a transparent layer and a bubble-containing layer for the purpose of reducing the cause of the occurrence of brown rings and facilitating thermal control when pulling up the silicon single crystal. In the transparent layer, there may be defects such as fine scratches that cannot be detected from visual observation or image data. Alternatively, the bubble-containing layer that appears to be composed of one layer when visually observed may actually be composed of a plurality of layer structures. Thus, in the layer structure in the thickness direction of the silica glass crucible, there may be a defect that is difficult to detect by visual inspection or the like.

Defects that cannot be detected by visual inspection, etc., may cause crystal defects such as transitions and damage to the silica glass crucible during ingot pulling of the silicon single crystal. It is desirable to determine in advance. However, as described above, visually, the silica glass crucible having defects and the silica glass crucible having no defects appear to be silica glass crucibles having a transparent layer and a bubble-containing layer in the same manner. Could not be determined.

A method for producing a silica glass crucible according to one embodiment of the present invention is a method for producing a silica glass crucible produced by a rotational mold method, and includes a cylindrical straight body having an opening at the upper end, a curved bottom, An upper end surface of a silica glass crucible or a silica glass crucible having a corner portion connecting the side wall portion and the bottom portion and having a curvature larger than that of the bottom portion, and wherein the upper end of the straight body portion is formed flat. A configuration is adopted in which there is a step of measuring the scattering state of each position in the thickness direction inside the side wall of the silica glass crucible of the laser light incident on the inner surface near the upper end.

According to the above invention, first, a laser beam such as a semiconductor laser or a solid laser is emitted in the thickness direction from the inside or outside of the silica glass crucible near the upper end of the silica glass crucible. The laser light incident on the silica glass crucible is transmitted or partially scattered depending on the structure of the layer in the thickness direction inside the side wall of the silica glass crucible.

Specifically, the laser light incident on the side wall of the silica glass crucible is transmitted through the light transmission layer without being scattered or reflected. On the other hand, the laser light is scattered in the light scattering layer.

The scattering state of the laser light entering the silica glass crucible is photographed using, for example, a camera, and the scattering state at each position in the thickness direction of the silica glass crucible is measured.

The laser light incident on the silica glass crucible causes various scattering situations such as transmission or partial scattering depending on the structure of the silica glass crucible (transparent layer, bubble-containing layer, presence or absence of defects, etc.). Therefore, image data corresponding to the layer structure in the thickness direction of the silica glass crucible can be acquired by photographing the end face of the silica glass crucible. By analyzing the image data, the layer structure in the thickness direction of the silica glass crucible can be continuously measured, and the layer structure in the thickness direction of the silica glass crucible can be measured easily and non-destructively. In addition, by manufacturing the silica glass crucible through the above process, the structure of the layer in the thickness direction of the silica glass crucible is continuously measured to determine the silica glass crucible having a problem in the layer structure in the thickness direction. A silica glass crucible having a desirable layer structure in the thickness direction can be produced.

Thus, according to the above invention, when producing a silica glass crucible, the laser light is emitted near the upper end of the silica glass crucible to be measured, and the laser light incident on the silica glass crucible is silica. It has the process of measuring the scattering condition of each position of the thickness direction inside a glass crucible side wall part. With the above configuration, when the silica glass crucible is manufactured, the scattering state at each position in the thickness direction of the silica glass crucible generated according to the structure of the layer in the thickness direction of the silica glass crucible can be measured. As a result, the layer structure in the thickness direction of the silica glass crucible can be measured easily and non-destructively, and the silica glass crucible having the desired layer structure in the thickness direction can be manufactured by discriminating the problematic silica glass crucible.

According to the above invention, the laser light incident into the silica glass crucible is scattered by any defects such as scratches even in the transparent layer, so by measuring the scattering of the laser light, Defects in the transparent layer that cannot be detected can be detected. It is also possible to measure whether or not a light transmission layer having a sufficient thickness necessary for pulling up the silicon single crystal is formed on the innermost surface side of the silica glass crucible. According to the said invention, the layer structure of the thickness direction of a silica glass crucible, such as the presence or absence of a light transmissive layer, and the thickness of a light transmissive layer, can be measured easily nondestructively. Therefore, a silica glass crucible having a desirable layer structure in the thickness direction, such as a silica glass crucible in which a sufficiently thick light transmission layer is formed, can be produced.

When a thin light transmission layer or light scattering layer is formed on the inner surface side of the silica glass crucible, when the silicon single crystal is produced, the light transmission layer is dissolved, etc. The light scattering layer containing defects is exposed to the silicon melt. Irregularities due to defects such as bubbles and scratches contained in the light scattering layer of the silica glass crucible appear on the contact surface between the silicon melt and the silica glass crucible, and so-called brown rings are concentrated on the contact surface. Therefore, there may be a problem such as a crystal defect of the pulled silicon single crystal. Therefore, it is desirable that a light transmission layer with a certain thickness is formed on the inner surface side of the silica glass crucible, and it is important to measure the layer structure in the thickness direction of the silica glass crucible.

Further, according to the above invention, if there is a layer structure in the light scattering layer, the incident laser light is scattered, and scattered light reflecting the layered structure is generated, so that the layer structure is known by measuring the scattered light. Can do. For example, if the scattered light intensity of the laser light is uniform within a certain range, it can be seen that the light scattering layer is composed of one layer in the thickness direction of the crucible.

When a plurality of layers are included in the bubble-containing layer, there may be a problem in the strength of the silica glass crucible due to the difference in the coefficient of thermal expansion of each layer. Therefore, by making the bubble-containing layer as a single layer, it is possible to reduce the risk of breakage of the silica glass crucible due to the difference in coefficient of thermal expansion. In order to reduce the breakage of the silica glass crucible due to the difference in thermal expansion coefficient or the like, it is desirable that the bubble-containing layer does not include a plurality of structures. That is, as described above, by measuring the layer structure of the light scattering layer or the bubble-containing layer, it is possible to determine a silica glass crucible with a low possibility of breakage due to a difference in coefficient of thermal expansion.

Furthermore, according to the above invention, for example, the thickness of the light scattering layer and the shape of the boundary between the light transmission layer and the light scattering layer can be measured, and a silica glass crucible or light transmission layer having a desirable light scattering layer thickness can be used. A silica glass crucible having a desirable shape at the boundary interface with the light scattering layer can be identified. And it becomes possible to manufacture a silica glass crucible having a desirable layer structure in the thickness direction.

In the crystal pulling step, the silicon melt interface is adjusted to be at the same position with respect to the heater of the silicon pulling device, and the crucible is controlled to move upward as the crystal pulling proceeds. In the pulling of the silicon single crystal, the temperature of the silicon single crystal growth part, that is, the boundary between the melt and the crystal where the silicon melt becomes the silicon single crystal is the melting point of silicon, and this boundary part is stabilized. In order to achieve this, very delicate temperature control is required.

If the silica glass crucible is composed of only a transparent layer, when the silicon melt in the silica glass crucible is heated with a heater, the radiant heat from the heater passes through the silica glass crucible and is directly transmitted to the silicon melt interface. Therefore, temperature control may be difficult. In order to perform appropriate temperature control when pulling up the silicon single crystal, it is desirable that a bubble-containing layer is provided outside the transparent layer, and the bubble-containing layer has an appropriate thickness. Therefore, by measuring the thickness of the light scattering layer, it is possible to discriminate a silica glass crucible that can easily perform appropriate temperature control. And it becomes possible to manufacture a silica glass crucible having a desirable layer structure in the thickness direction.

In addition, according to the invention, the laser light incident in the silica glass crucible is scattered at the interface formed in the thickness direction of the silica glass crucible. Can be measured. For example, when laser light is incident on a silica glass crucible, if scattered light of the laser light is observed in various places, it can be understood that a plurality of interfaces are formed in the silica glass crucible.

Generally, silica glass crucibles have the same silica network structure in the same layer. Therefore, once a crack occurs, the crack does not stop in the middle but expands in the layer, and the silica glass crucible may break. On the other hand, if there is an interface in the thickness direction, the structure of the silica network in each layer is different, so that the expansion of cracks stops at the interface portion, and cracking of the silica glass crucible due to the expansion of cracks can be prevented.

For example, the silica glass crucible can be annealed at a temperature equal to or higher than the fictive temperature to form an adjustment layer with a desired layer structure. Therefore, by selecting the silica glass crucible according to the above invention and performing an annealing treatment, a new layer can be formed in the thickness direction, and a crucible that is difficult to break can be manufactured.

Layer structure in the thickness direction of the silica glass crucible by emitting laser light from the end face direction of the silica glass crucible to each position in the thickness direction of the silica glass crucible and measuring Raman scattering generated according to the emitted laser light Can be grasped. That is, as an alternative to the above process, the Raman scattering generated according to the incident laser beam may be measured.

Further, in the method for producing the silica glass crucible, the step of measuring the scattering state of the laser light is a measurement target by emitting laser light from the inside of the silica glass crucible toward the thickness direction of the silica glass crucible. In the silica glass crucible, the scattering state of each position in the thickness direction inside the side wall of the silica glass crucible is measured from the annular end surface around the upper end opening of the portion where the laser light is incident. .

In this configuration, as a step of measuring the silica glass crucible, a laser light source is installed inside the silica glass crucible naturally cooled so as to emit laser light from the inside of the crucible toward the thickness direction of the silica glass crucible.

The present invention may be configured such that the state of scattering of the laser light incident into the silica glass crucible is photographed by using a camera or the like from the annular end surface direction around the upper end opening of the silica glass crucible. Laser light is incident from the inside to the outside of the silica glass crucible, and various scattering situations occur in the silica glass crucible. Therefore, when the scattering state of the laser light incident on the silica glass crucible is photographed from the end face direction of the silica glass crucible, image data corresponding to the layer structure in the thickness direction of the silica glass crucible can be acquired. By analyzing the image data, the structure of the layer in the thickness direction of the silica glass crucible can be easily measured without destruction, and a silica glass crucible having a desired quality can be discriminated. And it becomes possible to manufacture a silica glass crucible having a desirable layer structure in the thickness direction.

Laser light is emitted from the inside of the silica glass crucible toward the thickness direction of the silica glass crucible, and the scattering state of the laser light inside the silica glass crucible side wall portion is measured from the end surface direction, whereby the layer in the thickness direction of the silica glass crucible In addition to the structure, it is possible to easily determine non-destructive defects that cannot be visually confirmed in the layer structure. Further, the thickness of the light transmission layer can be easily measured without breaking. Based on the measurement result, a silica glass crucible having a desirable layer structure in the thickness direction can be identified.

Further, in the method for producing the silica glass crucible, the step of measuring the scattering state of the laser light may be performed by irradiating the silica glass crucible with illumination light having a predetermined wavelength corresponding to the wavelength of the emitted laser light. A configuration is adopted in which the scattering state of the laser beam is measured under irradiation.

According to this configuration, for example, when emitting red laser light to a silica glass crucible, blue illumination light is irradiated. In this case, it is better to avoid orange illumination having a hue close to the color of the laser light because the scattering of the laser light becomes inconspicuous.

Thus, by measuring the scattering state of laser light under illumination light adjusted according to the wavelength of the laser light, the scattering state of the laser light can be made clearer. And the structure of the layer in the thickness direction of the silica glass crucible can be measured with high accuracy, and the silica glass crucible having a desirable layer structure in the thickness direction can be easily determined without destruction.

Further, in the method for producing the silica glass crucible, the step of measuring the state of scattering of the laser light is performed by emitting a horizontal laser to the silica glass crucible and entering the silica glass crucible of the horizontal laser incident on the silica glass crucible. A configuration is adopted in which a step of measuring a scattering state at each position in the thickness direction is included.

Generally speaking, a horizontal laser is a line laser that is horizontal to the ground. According to this configuration, a horizontal laser is incident on the silica glass crucible with the silica glass crucible, and various laser light scattering conditions corresponding to the structure of the silica glass crucible over a wide range are photographed using an optical camera or the like. The image data can be acquired.

By configuring in this way, the layer structure in the thickness direction of the silica glass crucible in a wide range where the laser beam in the horizontal direction as described above is incident can be efficiently formed at the same time. The silica glass crucible having a desirable layered structure in the thickness direction can be measured more easily.

The silica glass crucible is manufactured by depositing silica powder on a rotating carbon mold and arc melting the deposited silica powder layer. Therefore, the layer structure of the transparent layer or the bubble-containing layer is symmetric with respect to the central axis of the crucible. On the other hand, since silica powder accumulates, the symmetry of the layer structure is not seen in the height direction of the silica glass crucible. Therefore, in order to grasp the characteristics of the silica glass crucible, it is more important to know the distribution of the layer structure in the height direction.

Here, when a vertical laser is used as the incident laser beam, the layer structure in the crucible height direction and the layer structure in the bubble-containing layer can be known in detail. The vertical laser refers to a vertical line laser (for example, a horizontal laser tilted by 90 degrees). Furthermore, by using a cross-line laser, it is possible to combine the advantages of a horizontal laser and a vertical laser.

In addition, by emitting laser light in an oblique direction (oblique direction toward the depth direction of the silica glass crucible, the angle may be arbitrary), for example, it is possible to determine at which depth a defect exists. It will be possible.

Thus, the present invention can use various lasers.

Further, in the method for producing the silica glass crucible, in the step of measuring the scattering state of the laser light, the laser light is emitted from the end surface direction of the silica glass crucible to each position in the thickness direction of the silica glass crucible, and is emitted. A configuration is adopted in which Raman scattering generated in response to laser light is measured at each position as the scattering state of the laser light.

According to this configuration, for example, scattered light from a silica glass crucible is removed through a Rayleigh light removal filter, and then dispersed through a spectroscope such as a diffraction grating and detected using a detector or the like. Thereafter, the information is converted into a Raman shift using an information processing apparatus or the like and displayed.

Generally, when performing Raman measurement on silica glass, it is known that a plurality of peaks such as a peak attributed to a planar four-membered ring and a peak attributed to a planar three-membered ring are measured. However, when a plurality of layer structures are included in the thickness direction of the silica glass crucible, the structure of the silica network is different in each layer, and thus the wave number value of each peak of the Raman shift varies at each position in the thickness direction. . Therefore, the layer structure of each layer can be measured by measuring the Raman shift at each position in the thickness direction of the silica glass crucible.

According to the above configuration, even a portion that looks like a transparent layer can be detected if the layer structure is different. Further, even if the bubble-containing layer has a plurality of layer structures, this can be detected. As a result, a silica glass crucible or the like that is likely to be deformed when the silicon single crystal is pulled can be identified.

Further, in the method for producing a silica glass crucible, in the step of measuring the scattering state of the laser light, the laser light is emitted over the entire circumference of the silica glass crucible at predetermined intervals, and the emitted laser light is emitted. The laser light scattering state corresponding to each is measured.

For example, when laser light is emitted from the inside of the silica glass crucible in the thickness direction of the silica glass crucible, the laser light source is rotated in a state where the laser light is emitted, so that the entire circumference of the silica glass crucible is obtained. Laser light can be incident.

Then, by moving the camera that captures the scattering state in accordance with the rotation of the laser light source, it is possible to capture the scattering state of the laser light generated over the entire circumference of the silica glass crucible by the rotation of the laser light source.

With this configuration, the structure in the thickness direction of the entire circumference of the silica glass crucible can be easily measured, and it becomes possible to determine a silica glass crucible in which no defect is detected over the entire circumference of the silica glass crucible. A silica glass crucible having a desirable layer structure in the thickness direction over the entire circumference can be produced.

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

(Example)
[Embodiment 1]
A crucible measuring device, a crucible measuring method, a crucible manufacturing method, and a silica glass crucible according to a first embodiment of the present invention will be described with reference to FIGS. The figure shows an example of the configuration of the crucible measuring apparatus. 2 to 4 are diagrams illustrating an example of a state where laser light is incident on a silica glass crucible when measured from the end surface direction. FIG. 5 is a flowchart showing an example of the flow of the crucible measurement method. 6 to 9 are diagrams illustrating examples of actual measurement images. FIG. 10 is a diagram showing the internal residual stress of the silica glass crucible shown in FIG. FIG. 11 is a diagram showing the internal residual stress of the silica glass crucible shown in FIG. 12 and 13 are diagrams illustrating an example of a scattering situation when a crossline laser is used.

In this embodiment, a crucible measuring apparatus that measures the scattering state of laser light at each position in the thickness direction inside the side wall of the silica glass crucible 1 having a transparent layer and a bubble-containing layer will be described. In addition, a crucible measurement method performed using the crucible measurement apparatus will be described. Moreover, the manufacturing method of the silica glass crucible manufactured through the method of measuring the said crucible is demonstrated. Moreover, the silica glass crucible 1 manufactured through the said crucible measurement is demonstrated. The crucible measuring apparatus according to the present embodiment is configured to emit laser light from the inside of the silica glass crucible 1 toward the thickness direction near the upper end of the silica glass crucible 1 as described later. Then, the crucible measuring device measures the scattering state of the laser light at each position in the thickness direction inside the side wall of the silica glass crucible 1 by photographing the silica glass crucible 1 from the end surface direction. Thereby, as will be described later, the structure in the thickness direction of the silica glass crucible 1 can be grasped. That is, by using the crucible measuring apparatus and the crucible measuring method described in this embodiment, a light transmission layer (a transparent layer that is free from defects such as scratches, that is, a layer that transmits laser light without scattering). And a light scattering layer (a region containing a defect such as a flaw even in a bubble-containing layer or a transparent layer; a layer that scatters laser light). As a result, defects such as scratches existing in the transparent layer can be easily found. In addition, the thickness of the light transmission layer and the light scattering layer can be measured. Further, by measuring the layer structure in the thickness direction of the silica glass crucible as described above when producing the silica glass crucible, the silica glass crucible 1 that reduces the possibility of problems when pulling up the silicon single crystal, It becomes possible to manufacture the silica glass crucible 1 which is not easily broken.

If light does not enter the light detector such as eyes, photodiodes, photomultiplier tubes, etc., light cannot be sensed.For example, even if laser light having a wavelength in the visible region is viewed from a direction perpendicular to the light traveling direction, the light is not Cannot be seen. However, in this case, if the laser beam is scattered by reflection or refraction by dust or particles in the air, the laser beam is visually recognized because the light enters the eyes or the like due to the scattering.

Since laser light having a wavelength in the visible region hardly scatters in silica glass as in air, it cannot be seen from a direction perpendicular to the traveling direction of light. When the photon of the laser beam interacts with the atoms constituting the silica glass, the vibration of the electric dipole formed by the atom is excited, and then the photon is emitted. The emitted photon becomes the secondary wave.

When many atoms are sparsely and randomly distributed, when these secondary waves are observed in an arbitrary direction, the intensity is the sum of the secondary wave intensity from each atom, and generally does not become zero. This is the case of light scattering. On the other hand, when the atoms constituting the silica glass are dense and the density is uniform, the secondary waves from each atom interfere with each other, and the intensity becomes zero except in a specific direction. Secondary waves that do not disappear as a result of interference become reflected or refracted waves.

Light scattering is generally caused by non-uniform substances. When laser light is scattered due to the presence of voids, bubbles, defects, etc. in non-uniform silica glass, the light becomes visible. Therefore, the presence of voids, bubbles, defects, layer boundaries, and the like can be known by scattering the laser light.

A silica glass crucible 1 that is a measurement target in the present embodiment connects a cylindrical side wall (straight barrel) having an opening at the upper end, a curved bottom, a side wall and a bottom, and has a curvature that is greater than that of the bottom. Has a large corner portion. Moreover, the upper end surface of the side wall part of the silica glass crucible 1 is formed as an annular flat surface. The silica glass crucible 1 in the present embodiment is a method for producing a silica glass crucible by, for example, depositing silica powder in a rotating mold (made of carbon) and arc melting the deposited silica powder layer. It is manufactured by the rotational mold method. Moreover, since the shape near the opening end part of the silica glass crucible 1 is likely to be uneven, the opening end part of the silica glass crucible 1 by a rotational molding method is cut with a predetermined width to align the shape of the opening end part.

FIG. 1 is an example of the configuration of the crucible measuring apparatus according to the first embodiment of the present invention. The crucible measuring apparatus photographs a laser light source 2 (light emitting portion) that emits laser light to the silica glass crucible 1 and a scattering state of the incident laser light in the silica glass crucible 1 from the end face direction of the silica glass crucible 1. A camera unit 3 (scattering state measuring unit).

The laser light source 2 is, for example, a solid laser source or a semiconductor laser source, and is arranged so that laser light is incident in the thickness direction of the silica glass crucible 1. Examples of the laser light source 2 include an AlGaInP (aluminum gallium indium phosphorus) based portable laser light source (output wavelength around 630 nm). In addition to the laser light source, a reflecting mirror or an optical fiber for laser transmission can be used for the light irradiation unit.

As shown in FIG. 1, the laser light source 2 in the present embodiment is installed inside the silica glass crucible 1 so as to emit laser light from the inside of the silica glass crucible 1 toward the thickness direction of the silica glass crucible 1. The By installing the laser light source 2 in this manner, laser light is incident on the silica glass crucible 1 from the inside to the outside of the silica glass crucible 1.

If the laser light source 2 emits laser light in the thickness direction of the silica glass crucible 1, the laser light source 2 is not only perpendicular to the normal direction of the side wall of the silica glass crucible 1 but also in an oblique direction. You may install so that light may be radiate | emitted. The laser light source 2 is preferably installed so that the laser light is incident and transmitted near the end face of the silica glass crucible 1 (for example, near the upper end of the silica glass crucible such as up to a depth of 2 cm from the end face). .

The laser light emitted from the laser light source 2 enters the silica glass crucible 1 after passing through the air, for example, and transmits or partially scatters depending on the structure of the silica glass crucible 1. Various scattering situations are shown at each position.

Since silica glass is amorphous, there is basically no crystal grain boundary that causes light scattering. Silica glass appears transparent to the human eye in the visible wavelength range of about 400 to 800 nm. Being transparent in the visible wavelength region of silica glass means that light in this wavelength region is not absorbed or scattered. Light absorption occurs with light having a wavelength of about 400 nm or less due to the energy gap of silica glass, but light with a wavelength exceeding that wavelength is not absorbed, and light oscillation due to plasma oscillation of free electrons in silica glass. Since scattering occurs with light having a wavelength of about 780 nm or more, light having a wavelength shorter than that wavelength is not scattered. In general, the wavelength range in which the light transmittance of silica glass is relatively high varies depending on the production method, raw materials, and the like, but is about 200 nm to 4000 nm.

Therefore, in the transparent layer of the silica glass crucible 1 where there are no defects such as scratches, the laser light emitted by the laser light source 2 (emits 630 nm laser light) is transmitted without being absorbed or scattered (straightly traveling). To do).

On the other hand, in the bubble-containing layer of the silica glass crucible 1, the laser light is scattered at the boundary between the bubbles and the silica glass. Therefore, when the laser beam emitted from the laser light source 2 enters the bubble-containing layer, a part of the laser beam is scattered. Further, even in a region that is visually determined to be transparent (a transparent layer), if a defect such as a scratch exists in the region, a part of the laser light is scattered by the defect.

Since silica glass has the property of interacting with ultraviolet rays and infrared rays, it is desirable that the laser light source 2 emit a visible light laser (in the range of about 400 to 800 nm). Examples of the laser light source 2 used in this embodiment include a red wavelength laser (for example, about 635 nm and about 650 nm), a green wavelength laser (for example, about 532 nm), and a blue wavelength laser (for example, about 410 nm). ) Etc. are used. In the present embodiment, a laser other than visible light such as a deep ultraviolet laser (for example, 230 to 350 nm) may be used as the laser light source 2.

The above-mentioned interaction between silica glass and light in the infrared region is caused by excitation of vibration between ions constituting the glass. Since ions constituting the glass are derived from impurities in the silica glass, the smaller the impurities, the less light is absorbed. Moreover, the light absorption characteristics also change depending on the structure of the silica network depending on the state during glass production. On the other hand, the interaction between silica glass and light in the ultraviolet region is caused by electronic excitation, so that it is different from the interaction with light in the infrared region. Electron excitation depends on the band gap between the valence band and the conduction band of silica glass. By introducing impurities such as alkali metal, the band gap is reduced, and the absorption edge may extend to the visible region.

In the present embodiment, for example, the laser light source 2 having a laser diameter of about 5 to 20 mm measured at a distance of 3 m and an output of about 0.2 mw to 500 mw is used. The exit diameter of the laser light source 2 is, for example, about 0.8 to 5.5 mm. The laser diameter, output, and exit aperture of the laser light source 2 may be other than those exemplified above.

The camera unit 3 is a general camera having an imaging element (not shown) such as a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal Oxide Semiconductor) image sensor, a lens unit, and the like. The camera unit 3 in the present embodiment is installed at a position where the end face of the silica glass crucible 1 to be measured can be photographed (that is, in the end face direction), and the laser light incident on the silica glass crucible 1 by the laser light source 2. The scattering state of the light in the thickness direction inside the side wall of the silica glass crucible 1 is configured to be measured from the direction of the annular end face around the upper end opening of the portion where the laser light is incident. Specifically, for example, referring to FIG. 1, when the silica glass crucible 1 is installed downward, the camera unit 3 is installed on the lower side of the silica glass crucible 1 so that the lens unit faces upward. Is done.

As described above, the laser light incident on the silica glass crucible 1 shows various scattering states according to the structure of the silica glass crucible 1 at each position in the thickness direction of the silica glass crucible 1. Therefore, the camera unit 3 acquires image data indicating the scattering state of laser light at each position in the thickness direction inside the side wall of the silica glass crucible 1 by photographing the end surface of the silica glass crucible 1. Thereafter, the camera unit 3 displays the acquired image data on a display unit (not shown), for example.

For example, when observing an object with an optical microscope or a metal microscope, transmitted light or reflected light is used. When observing an object using laser light or the like, it is common to observe the object using transmitted light or reflected light. Therefore, the observation device such as the camera unit 3 generally has a silica glass crucible 1 at a position where the reflected light or the transmitted light can be observed, that is, in the vicinity of the laser light source 2 that is the light emitting unit. It is installed in the position on the opposite side across the side wall portion.

On the other hand, in the present invention, as described above, the camera unit 3 is installed at a position in the vertical direction (that is, the end surface direction) as viewed from the incident direction of the laser beam, where the end surface of the silica glass crucible 1 can be photographed. As described above, in the present invention, by arranging the camera unit 3 at a position different from a general position, image data indicating the scattering state at each position in the thickness direction of the silica glass crucible 1 can be simply and nondestructively. Can be obtained, and the structure of the layer in the thickness direction can be measured.

2 to 4 are schematic diagrams of image data acquired by the camera unit 3 as a scattering state of laser light incident on the silica glass crucible 1. The state of laser light scattering is indicated by two lines, and the intensity of laser light scattering is expressed by the interval between the two lines. In FIGS. 2 to 4, the region where the laser light scattering is large is expressed with a wide interval between the two lines, and the region where the laser light scattering is small is expressed with a small interval between the two lines. . Further, the region other than between the two lines indicates that the laser beam is not incident or transmitted, that is, the laser beam is not scattered. If the frequency of scattering increases, the intensity of the scattered light increases. Conversely, if the frequency of scattering decreases, the intensity of the scattered light decreases.

FIG. 2 shows that laser light is incident from the inner surface of the silica glass crucible 1, and the incident laser light is transmitted without being scattered in the transparent layer on the inner surface side, but is scattered in the bubble-containing layer.

FIG. 3 shows that there is a transparent layer on the inner surface side of the silica glass crucible 1 as in FIG. 2, and there are regions where the intensity of the scattered laser light is different in the bubble-containing layer. The intensity of the scattered laser light is strong in the bubble-containing layer near the transparent layer and near the outside, and the scattering intensity is weak in the region between them. This is because the bubble-containing layer, which is a light scattering layer, is composed of a plurality of layers.

FIG. 4 shows that the incident laser light is scattered by the bubble-containing layer and further scattered by the transparent layer region as in FIG. This indicates that there are defects such as scratches that become scattering centers that cannot be visually confirmed in the transparent layer region. By measuring the laser scattered light, defects in the transparent layer that cannot be detected visually are discovered. I can do it.

As described above, the camera unit 3 shows the state of the laser light incident on the silica glass crucible 1 that shows various scattering states such as transmission or partial scattering according to the layer structure in the thickness direction of the silica glass crucible 1. The image data indicating is acquired. By referring to the image data acquired by the camera unit 3, the layer structure in the thickness direction of the silica glass crucible 1 can be easily discriminated without destruction.

FIG. 5 is a flowchart showing an example of the flow of the crucible measurement method according to the first embodiment.

As shown in FIG. 5, laser light is emitted from the inside of the silica glass crucible 1 toward the thickness direction of the silica glass crucible 1 using the laser light source 2 (step S101). Thereby, the laser light is incident on the silica glass crucible 1. Thereafter, the laser light incident on the silica glass crucible 1 exhibits various scattering states such as transmission or partial scattering depending on the structure of the silica glass crucible 1.

Subsequently, the end surface inside the side wall portion of the silica glass crucible 1 is photographed by the camera unit 3 to obtain image data indicating the scattering state of the laser light at each position in the thickness direction of the silica glass crucible 1 (step S102). . Thereafter, the camera unit 3 displays the acquired image data on the display device, for example.

In addition, the crucible measuring apparatus in this embodiment analyzes the image data acquired by the camera unit 3, and the structure of the silica glass crucible 1 in the thickness direction such as a light transmission layer or a light scattering layer (light transmission layer, light An image analysis unit (not shown) for determining the thickness of the scattering layer and the light transmission layer can be provided. The crucible measurement method can be configured to analyze the image data and determine the structure of the layer in the thickness direction of the silica glass crucible 1 (light transmission layer, light scattering layer, light transmission layer thickness, etc.).

The image analysis unit is a general information processing device including, for example, an arithmetic device and a storage device, and a function of analyzing image data acquired by the camera unit 3 when the arithmetic device executes a program stored in the storage device. Will be realized. That is, the image analysis unit determines the layer structure in the thickness direction of the silica glass crucible 1 based on the image data. This makes it possible to automatically determine the layer structure in the thickness direction of the silica glass crucible 1.

In the present embodiment, when the laser beam is incident on the silica glass crucible 1, the laser beam may be incident so that the incident angle becomes a Brewster angle. In this case, the laser light source 2 may be configured to emit a p-polarized laser. Note that p-polarized light refers to polarized light whose direction of vibration of the electric field is parallel to the incident surface.

With this configuration, the laser light emitted from the laser light source 2 can be incident without being reflected at the interface between the air and the silica glass crucible 1, so that all can be used for observation of the layer structure and the like. The state of the silica glass crucible 1 can be observed. In addition, when observing the scattering state of laser light, reflection does not occur at the interface between air and the silica glass crucible 1, and therefore, for example, the detection of the structure and defects of layers near the interface is affected by the reflected light. Can be done without.

Note that the incident angle does not necessarily have to be exactly the Brewster angle. By emitting laser light so as to approach the Brewster angle, a certain degree of effect can be obtained even if the angle is not accurate.

Since the vicinity of the upper end portion of the silica glass crucible 1 where the laser light is incident from the laser light source 2 is a side wall portion having a cylindrical shape, the laser light is incident on the curved surface, and the position of the laser light source 2 is shifted. In some cases, the incident angle changes and the Brewster angle is not reached. Furthermore, as described above, since the silica glass crucible 1 is made by, for example, the rotational molding method, the shape of the manufactured silica glass crucible 1 may be deviated from the design drawing. Therefore, it is necessary to accurately determine the emission position and the incident angle of the laser beam so that the incident angle becomes the Brewster angle at the determined position, and to make the laser beam incident.

For example, a 32 inch silica glass crucible has an inner diameter of about 81.3 cm and a mass of 50 kg to 60 kg, and a 40 inch silica glass crucible has an inner diameter of about 101.6 cm and a mass of 90 kg to 100 kg. Is a large heavy object. In order to observe the scattered light by irradiating laser light at the required measurement position with such a silica glass crucible and observing the scattered light, the installation position and the installation angle are accurately adjusted by moving the silica glass crucible 1 itself. It is difficult to do.

Therefore, for example, using a robot arm or the like, the three-dimensional shape (three-dimensional coordinates) of the inner surface of the silica glass crucible 1 is measured in advance, and the position and angle at which the laser beam is emitted with respect to the measurement position are calculated. Since it can measure for every measurement point, changing the position and angle of a laser light source, the installation position adjustment of the silica glass crucible 1 itself becomes unnecessary.

The three-dimensional shape measurement of the inner surface of the silica glass crucible 1 is performed, for example, by providing an internal distance measuring unit such as a laser displacement meter at the tip of the robot arm and contacting the inner distance measuring unit along the inner surface of the crucible. Measure by moving with. Specifically, silica glass is emitted by emitting laser light obliquely with respect to the inner surface of the silica glass crucible 1 at a plurality of measurement points on the movement path of the internal distance measuring unit, and detecting the reflected light. The three-dimensional shape of the inner surface of the crucible 1 can be measured. Then, by utilizing the measurement result, laser light can be easily emitted so that the incident angle becomes the Brewster angle with respect to the silica glass crucible 1.

As described above, according to the crucible measuring apparatus and the measuring method in the present embodiment, the thickness of the light transmission layer and the light scattering layer can be measured. When measuring the thickness of the light transmission layer or the light scattering layer, the incident angle is deviated from the normal direction of the incident surface (that is, the laser light is incident on the silica glass crucible 1 in an oblique direction rather than a vertical direction. ) And the error becomes large, and accurate measurement cannot be performed. Therefore, it is desirable that the incident angle θ (angle from the normal direction of the incident surface) of the laser light emitted from the laser light source 2 is emitted so as to satisfy the following formula. In the following equation, the thickness of the silica glass crucible 1 (the thickness of the light transmission layer and the light scattering layer) is represented by T, and the allowable error is represented by ΔT.

From the above formula, the relationship among the thickness T, the tolerance ΔT, and the incident angle θ of the silica glass crucible 1 is shown in Table 1. For example, when the thickness of the crucible is 10 mm, the allowable incident angle of the laser beam when the tolerance is 0.1 mm is within 8.0 °. Thus, by controlling the laser light source 2 so that the incident angle θ according to the thickness T of the silica glass crucible 1 and the allowable deviation ΔT, the thickness of the silica glass crucible 1 is within an allowable error range. (For example, the thickness of the light transmission layer or the light scattering layer) can be measured. When controlling the angle θ, it is desirable to use the measurement result of the three-dimensional shape of the inner surface of the silica glass crucible 1 by the internal distance measuring unit described above, and accurate control of the angle θ without deviation at each point. It can be performed.

Further, in order to reduce the error when measuring the thickness of the light transmission layer or the light scattering layer, the laser diameter B of the laser light (the laser diameter of the portion that is in contact with the silica glass crucible 1) satisfies the following formula. It is desirable to be controlled. In the following equation, an allowable error is represented by ΔT, a thickness of the silica glass crucible 1 is represented by T, and a laser diameter is represented by B.

From the above formula, the relationship among the thickness T, tolerance ΔT, and laser diameter B of the silica glass crucible 1 is shown in Table 2. For example, when the thickness of the crucible is 10 mm, the allowable laser diameter when the tolerance is 0.1 mm is 1.4 mm. By controlling the laser light source 2 so that the laser diameter B corresponds to the wall thickness T and the allowable deviation ΔT of the silica glass crucible 1 as shown in Table 2, the silica glass crucible 1 is within the allowable error range. Can be measured (for example, the thickness of the light transmission layer or the light scattering layer).

The place where the laser beam is incident is not limited to the inside of the silica glass crucible 1. Laser light may be incident from the outside toward the inside in the thickness direction of the silica glass crucible 1. Further, laser light may be incident from the end face direction of the silica glass crucible 1 and the scattering state of the laser light may be measured from the inside of the silica glass crucible 1. In this case, the scattering state is measured while moving the position of the emitted laser light in the thickness direction of the silica glass crucible 1. By doing in this way, it can grasp | ascertain that the unevenness | corrugation is formed in the transparent layer or the bubble containing layer inside the silica glass crucible 1.

Further, for example, the laser light source 2 is set at a predetermined interval (for example, every 2 to 3 degrees, 5 degrees, and 10 degrees, any angle) with the laser light emitted from the inside of the silica glass crucible. It is possible to make the laser light incident on the entire circumference of the silica glass crucible 1. At this time, by moving the camera unit 3 in accordance with the rotation of the laser light source 2, it is possible to measure the scattering state of the laser light at each position over the entire circumference of the silica glass crucible 1. As a result, it is possible to measure the structure in the thickness direction of the silica glass crucible 1 over the entire circumference of the silica glass crucible 1 by an easy method.

In addition, by measuring over the entire circumference of the silica glass crucible 1 in this way, the thickness distribution and roundness of each layer when there are a plurality of concentric layers at the upper end of the silica glass crucible can be measured. Moreover, the roundness of the boundary between the transparent layer and the bubble-containing layer can also be measured. Since the roundness of the inner surface of the silica glass crucible 1 can also be measured, the silicon single crystal is pulled by using the roundness of the inner surface of the silica glass crucible 1 and the roundness of the boundary between the transparent layer and the bubble-containing layer. It is possible to calculate whether a transparent layer having a necessary thickness is formed. Furthermore, if the distribution of the layer thickness of the silica glass crucible is uneven when pulling up the silicon single crystal, the heat transfer is not uniform and the temperature distribution of the silicon melt can be uneven. As a result, it becomes difficult to keep the position of the contact interface between the silicon single crystal and the silicon melt constant, and inconveniences such as dislocation may occur. By measuring the silica glass crucible 1 using the crucible measuring apparatus and the crucible measuring method of the present embodiment, it is possible to determine the silica glass crucible in which a problem such as the occurrence of dislocation occurs. In addition, when measuring over the perimeter of the silica glass crucible 1, it is more desirable to carry out by the combination with the horizontal laser mentioned later.

In the present embodiment, the case where the laser light source 2 that is a unidirectional laser such as a laser pointer is used as the light emitting portion has been described. For example, the laser light source 2 can be configured to emit at a wide angle (for example, the laser beam 2 is emitted with a predetermined angle (eg, 2 to 4 times) larger than the incident angle of the incident laser light. Realized by passing the lens through). Alternatively, a line laser (horizontal laser, vertical laser) or a cross line laser may be used as the light emitting portion. The cross line laser emits laser light in the horizontal direction and the vertical direction by transmitting the emitted laser light through a collimating lens and then through a cylindrical rod lens.

Thus, by using a line laser or a cross line laser as the light emitting part, a wide range of scattering conditions can be measured at once. For example, by using a surface laser and a horizontal line laser (horizontal laser), the layer structure inside the side wall of the silica glass crucible 1 can be measured at once over a wide range. Thereby, the measurement of the layer structure can be performed without omission over the entire range. In addition, by using a vertical line laser (vertical laser: for example, a horizontal laser tilted by 90 degrees) or a cross line laser, it is possible to more clearly determine the layer structure in the bubble-containing layer and the layer structure in the depth direction. It becomes possible to make a judgment. Further, the oblique direction is oblique to the depth direction of the silica glass crucible 1. The depth at which the defect is located can be determined by emitting the laser at any angle.

When a cross-line laser or the like is used as the laser light source 2 in the present embodiment, for example, when the line width is about 2 mm within a distance of 5 m and the light is incident on a flat incident object with a distance from the laser light source 2 to the incident object. Although there is no limitation on the ratio to the line length of the laser beam, it is preferable to use, for example, a ratio of about 1: 0.3 to 2.

The manufacturing method of the silica glass crucible of this embodiment discriminate | determines the silica glass crucible 1 which has each advantageous point mentioned above through the process of measuring the scattering condition of each position of the thickness direction of the silica glass crucible 1 mentioned above. Can be manufactured.

The silica glass crucible forming step is performed by (1) rotating a mold having a bowl-shaped inner surface that defines the outer shape of the silica glass crucible, and crystalline or amorphous silica on the inner surface (bottom and side surfaces) of the mold. By depositing the powder to a predetermined thickness, a silica powder layer for the silica glass layer is formed. (2) The silica powder layer is heated to 2000 to 2600 ° C. by arc discharge to melt and solidify to form glass. And (3) cutting the opening end with a predetermined width and aligning the shape of the opening end.

The silica glass crucible inspection step includes the step of measuring the scattering state of each position in the thickness direction of the silica glass crucible described above, and is performed on the silica glass crucible that has undergone the silica glass crucible formation step. By selecting a good silica glass crucible in this inspection step, a silica glass crucible having the above-mentioned advantages can be manufactured.

As described above, when the silica glass crucible 1 is manufactured, by measuring the scattering state of each position in the thickness direction of the silica glass crucible 1, the structure in the thickness direction of the manufactured silica glass crucible 1 (transmission layer, Light scattering layer). Therefore, it is possible to easily determine whether the layer structure in the thickness direction of the manufactured silica glass crucible 1 is desirable by performing the above-described steps when manufacturing the silica glass crucible 1. . As a result, the silica glass crucible 1 having a desirable layer structure in the thickness direction can be identified and manufactured. Specifically, for example, a silica glass crucible 1 in which a light transmission layer is formed on the innermost surface side, and the light transmission layer has a sufficient thickness necessary for pulling up a silicon single crystal. The silica glass crucible 1, the silica glass crucible 1 in which a light scattering layer is formed outside the light transmission layer, and the light scattering layer are composed of one layer (that is, in the region where the laser light is scattered, Silica glass that is uniform according to preset criteria such as no difference in intensity of scattering, or slight difference in intensity (for example, a light transmission layer is not formed in the light scattering layer). Crucible 1) Silica glass crucible 1, silica glass crucible 1 having a single bubble-containing layer, silica glass crucible 1 having a desired light scattering layer thickness, interface at the boundary between the light transmission layer and the light scattering layer But Silica glass crucible 1 is preferable shape (so that, for example, silica glass crucible 1 has no unevenness in the distribution of the light transmitting layer) can be manufactured like. Further, the silica glass crucible 1 in which the light transmission layer is formed over the entire inner surface of the opening end of the silica glass crucible 1, or the light transmission layer has a thickness within a predetermined range over the entire circumference of the silica glass crucible 1. A value obtained by dividing the roundness of the shape of the boundary between the light transmission layer and the light scattering layer by the diameter of the crucible is predetermined. A silica glass crucible 1 configured to be smaller than a numerical value (for example, 0.01, 0.005, or 0.002) can be manufactured.

シリカ Silica glass crucibles are used to manufacture silicon single crystals by the Czochralski method. A silica glass crucible is filled with polysilicon and heated to melt high-purity polysilicon to obtain a silicon melt. A silicon single crystal is produced by rotating the susceptor holding the silica glass crucible while immersing the end of the seed crystal in the silicon melt and rotating the susceptor. At that time, by using the silica glass crucible according to the present embodiment and the like, it is possible to reduce the occurrence of crystal defects in the silicon single crystal ingot caused by the crucible defects.

FIGS. 6 to 9 are images taken using the camera unit 3 of the scattering state of the laser light when the laser light is actually incident on the silica glass crucible 1 from the inside.

FIG. 6 shows a state in which the laser light incident on the silica glass crucible 1 is partially scattered after being transmitted from the inside of the silica glass crucible 1 to a predetermined position. The silica glass crucible 1 includes a light transmission layer (transparent layer having no defects) that is a region through which laser light is transmitted, and light scattering that is located outside the light transmission layer and is a region in which laser light is scattered. It has a layer (such as a bubble-containing layer), and it can be seen that the light scattering layer has a single structure.

FIG. 7 shows a state where the incident laser light is strongly scattered once after being transmitted from the inside of the silica glass crucible 1 to a predetermined position, and then the scattering is weakened and then strongly scattered again. It can be seen that the silica glass crucible 1 has a light transmission layer and a light scattering layer outside the light transmission layer, and the light scattering layer is composed of a plurality of layers.

FIG. 8 shows that after the incident laser light is transmitted from the inside of the silica glass crucible 1 to a predetermined position, it is strongly scattered once, and once the scattering is interrupted, the laser light is scattered again. The silica glass crucible 1 has a light-transmitting layer and a light-scattering layer outside the light-transmitting layer, and it can be seen that the light-scattering layer is composed of a plurality of layers.

FIG. 9 shows that the incident laser light is scattered from the beginning, then once transmitted, and then scattered again. The silica glass crucible 1 has a light transmissive layer and a light scattering layer outside the light transmissive layer, and has a defect in an inner portion of the silica glass crucible 1 that is considered to be in the transparent layer (light It can be seen that a scattering layer is formed).

FIGS. 10 and 11 show the strain (internal residual stress) of the silica glass crucible 1 of FIGS. As shown in FIG. 10, in the silica glass crucible 1 of FIG. 6 (silica glass crucible having a light transmission layer and a light scattering layer, and it is determined that the light scattering layer has a single structure) Although there is a boundary of internal residual stress between the light transmission layer and the light scattering layer, it can be seen that the internal residual stress changes gently in the other portions. In addition, since silica glass has birefringence, if there is an abrupt change in internal residual stress, the refractive index changes abruptly and contrast is seen.

As shown in FIG. 11, in the silica glass crucible 1 of FIG. 7 (silica glass crucible having a light transmission layer and a light scattering layer, and it is determined that the light scattering layer includes a plurality of layers). It can also be seen that there is a boundary (rapid change) of internal residual stress even inside the light scattering layer.

Thus, there is a correspondence between the laser light scattering state of the silica glass crucible 1 and the distortion. The strain is the same as the silica glass is compressed or pulled at the atomic level and the Si—O—Si bond distance (atomic density) is non-uniform. It is thought that has caused.

The strain inspection is generally a destructive inspection and is performed by breaking the silica glass crucible 1. Therefore, the non-destructive and simple measurement of the laser light scattering state according to the present invention is performed instead of the distortion inspection, whereby the distortion inspection can be easily performed. Further, the scattering state of the laser light can be measured, and annealing treatment or the like can be performed according to the result of the measurement (if necessary).

When the polycrystalline silicon is incorporated into the silica glass crucible 1 in order to produce a silicon single crystal, there is a case where an indentation is formed inside the silica glass crucible 1 due to the polycrystalline silicon. In such a case, if the strain in the silica glass crucible 1 is large, the silica glass crucible 1 may be cracked due to the indentation. However, the crack may not be generated immediately after the indentation is formed. Accordingly, the single crystal silicon pulling process may break, and in particular, when the silica glass crucible 1 is broken during the melting of the silicon, the pulling apparatus is damaged and the silicon raw material is discarded, which is economical. Loss. According to the measuring method of the present invention, it becomes possible to substitute for the strain measurement of the silica glass crucible 1 by a non-destructive and easy method, and it is possible to prevent the above damage from occurring in advance.

12 and 13 are diagrams showing a scattering state when a cross-line laser is used. FIG. 12 is a photograph of the scattering state in the thickness direction of the silica glass crucible 1 when laser light is emitted using a cross-line laser. All images photographed by the camera unit 3 are obtained using a cross-line laser. It can be seen that the light transmission layer and the light scattering layer can be discriminated in the range.

When a cross-line laser is used, it is possible to measure a wide range of scattering conditions, and it may be possible to determine, for example, a rim end processing trace other than the structure of the light transmission layer and the light scattering layer. FIG. 13 shows that the incident crossline laser light is also scattered in the transparent layer region.

[Embodiment 2]
A second embodiment of the present invention will be described with reference to FIGS. FIG. 14 shows an example of the configuration of the crucible measuring apparatus according to this embodiment. FIG. 15 is a flowchart illustrating an example of the flow of the crucible measurement method according to the second embodiment. FIG. 16 is a diagram illustrating the influence of the distance between the inner surface of the crucible and the illumination unit on the measurement of the scattering state.

In the present embodiment, a crucible measuring device that measures the scattering state of laser light incident on the silica glass crucible 1 under irradiation with light of a predetermined wavelength will be described. In addition, a crucible measurement method performed using the crucible measurement apparatus will be described. Moreover, the manufacturing method of the silica glass crucible manufactured through the measurement of a crucible is demonstrated. Moreover, the silica glass crucible 1 manufactured through the measurement of the crucible will be described.

As shown in FIG. 14, the crucible measuring apparatus according to this embodiment includes a laser light source 2, a camera unit 3, and an illumination unit 4. The configurations of the laser light source 2 and the camera unit 3 are the same as those described in the first embodiment. Therefore, the overlapping description is omitted.

The illumination unit 4 is configured by, for example, an LED (Light emitting diode), and is configured to irradiate light having a wavelength corresponding to the wavelength of the laser light emitted from the laser light source 2. Specifically, for example, when the laser light source 2 emits red laser light, the illumination unit 4 is configured to emit light having a blue wavelength.

The light (illumination) emitted by the illumination unit 4 is desirably avoided because illumination with a hue close to that of the laser light makes the laser light scattering inconspicuous. That is, it is desirable that the illumination unit 4 irradiates light that does not include a wavelength near the wavelength of the laser light emitted from the laser light source 2. As an example, when the wavelength of light emitted from the laser light source 2 is 630 nm, it is desirable to use illumination of light having a blue wavelength that does not include a wavelength near 630 nm. When white light is applied to an object and the reflected light looks red, it is because the object reflects light having a wavelength in a region where the human eye looks red and absorbs light of other wavelengths. Therefore, even if the light of only the wavelength of the region that looks blue with human eyes is applied, the object does not look red.

When the laser light source 2 is incident on the silica glass crucible 1, the illumination unit 4 emits light adjusted according to the wavelength of the laser light, and the camera unit 3 is the end surface of the silica glass crucible 1. Can be used to measure the state of laser light scattering. As a result, the layer structure in the thickness direction of the silica glass crucible 1 can be measured with higher accuracy.

Next, an example of the crucible measurement method performed using the crucible measurement apparatus will be described with reference to FIG.

Referring to FIG. 15, first, laser light is emitted from the inside of the silica glass crucible 1 toward the thickness direction using the laser light source 2 (step S101). As a result, the laser light is incident on the silica glass crucible 1. Thereafter, the laser light incident on the silica glass crucible 1 shows various scattering states such as transmission or partial scattering depending on the structure of the silica glass crucible 1.

Subsequently, or before and after the emission of the laser beam, the illumination unit 4 is used to irradiate illumination light corresponding to the laser beam (S201). Thereby, the laser light is incident on the silica glass crucible 1 under illumination by the illumination unit 4.

Then, the end face of the silica glass crucible 1 is photographed by the camera unit 3. Thereby, the camera part 3 measures the scattering state of the laser beam at each position in the thickness direction of the silica glass crucible 1 under illumination by the illumination part 4. That is, image data indicating the scattering state of the laser light is acquired by photographing the end face of the silica glass crucible 1 with the camera unit 3 (step S102). Thereafter, the camera unit 3 displays the acquired image data on the display device, for example.

Thus, the crucible measurement method in this embodiment measures the scattering state of each position in the thickness direction of the silica glass crucible 1 under irradiation with illumination light. As a result, the structure of the layer in the thickness direction of the silica glass crucible 1 can be grasped based on the measurement result.

FIG. 16 shows the relationship of ease of measurement of the scattering state of the laser light depending on the distance between the inner surface (or end face) of the silica glass crucible 1 and the illumination unit 4. Specifically, FIG. 16A shows a case where the distance between the inner surface of the silica glass crucible 1 and the illumination unit 4 is 100 mm, and FIG. 16B shows the inner surface of the silica glass crucible 1. The case where the distance with the illumination part 4 is 300 mm is shown. FIG. 16C shows a case where the distance between the inner surface of the silica glass crucible 1 and the illumination unit 4 is 500 mm.

As shown in FIG. 16, in the used laser light source 2 and the illuminating unit 4, when the distance between the inner surface of the silica glass crucible 1 and the illuminating unit 4 is about 500 mm, the laser light scattering state is the most. It can be seen that it can be measured clearly. Thus, by adjusting the distance between the inner surface of the silica glass crucible 1 and the illumination unit 4, the scattering state of incident laser light can be measured more clearly. In other words, the illumination unit 4 is preferably adjusted so that the distance from the inner surface of the silica glass crucible 1 is a predetermined distance (for example, 500 mm). In addition, it is possible that the suitable distance between the silica glass crucible 1 and the illumination part 4 changes according to the intensity of the irradiation light which the illumination part 4 irradiates, etc., for example. Therefore, it is assumed that the predetermined distance is a distance that can be adjusted as necessary.

The crucible measuring apparatus and measuring method in the present embodiment can employ various other configurations as in the case described in the first embodiment. For example, it is also effective to combine the illumination unit 4 with the above-described line laser or cross line laser (light emitting unit). In particular, for example, by emitting red laser light under illumination of blue illumination light by the illumination unit 4, the scattered portion can be measured as purple, and the scattering state can be measured more clearly. Become.

When manufacturing the silica glass crucible 1 using the rotating mold method, it is more easily desirable through the step of measuring the scattering state of each position in the thickness direction of the silica glass crucible 1 under illumination with the illumination light described above. The silica glass crucible 1 can be manufactured and realized.

[Embodiment 3]
Next, a third embodiment of the present invention will be described with reference to FIGS. FIG. 17 is an example of the configuration of the crucible measuring apparatus according to the present embodiment. FIG. 18 is a diagram illustrating an example of a position where the crucible measurement apparatus according to the present embodiment measures a Raman spectrum. FIG. 19 is a flowchart illustrating an example of the flow of the crucible measurement method according to the third embodiment. 20 and 21 are examples of Raman spectra actually measured.

In this embodiment, a crucible measuring apparatus that measures the scattering state of laser light in the thickness direction of the silica glass crucible 1 by measuring a Raman spectrum (measuring Raman scattering) will be described. Moreover, the crucible measuring method performed using the said apparatus is demonstrated. Moreover, the silica glass crucible 1 manufactured through the measurement of the crucible will be described.

Referring to FIG. 17, the crucible measuring apparatus according to this embodiment includes, for example, a laser unit 21 (light emitting unit) and a Raman spectroscopic measuring unit 31 (scattering state measuring unit). The Raman spectroscopic measurement unit 31 includes, for example, a Rayleigh light removal filter 311, a spectroscope 312, and a detector 313.

The laser unit 21 is, for example, a semiconductor laser or a solid-state laser, and is monochromatic laser light at each position in the thickness direction of the silica glass crucible 1 from the end surface direction of the silica glass crucible 1 toward the end surface of the silica glass crucible 1. (For example, 520 nm green laser light) is emitted. That is, as shown in FIG. 17, the laser unit 21 emits laser light to the end surface of the silica glass crucible 1 while moving the emission position in the thickness direction of the silica glass crucible 1. Thereby, as will be described later, the Raman spectrum at each position in the thickness direction of the silica glass crucible 1 is measured.

As described above, the Raman spectroscopic measurement unit 31 includes the Rayleigh light removal filter 311, the spectroscope 312, and the detector 313.

The Rayleigh light removal filter 311 is a filter for removing Rayleigh scattering that is included in the scattered light and has the same wavelength as the emitted laser light. The laser light emitted from the laser unit 21 enters the end surface of the silica glass crucible 1 and then generates scattered light. This scattered light includes Rayleigh scattered light in addition to Raman scattered light to be measured (Stokes, anti-Stokes, or either). Therefore, the Rayleigh light removal filter 311 is used to remove Rayleigh scattered light.

Subsequently, the light that has passed through the Rayleigh light removal filter 311 enters the spectroscope 312. Then, the spectroscope 312 separates the scattered light from which the Rayleigh scattered light has been removed. After that, using the detector 313, the dispersed light is detected for each wavelength. With such a configuration, the crucible measuring apparatus in the present embodiment measures the scattering state at each position in the thickness direction of the silica glass crucible 1. Further, the detector 313 is connected to, for example, an information processing device (not shown), and the information processing device can calculate a Raman shift value corresponding to the detected light. Thereby, the Raman spectrum is measured. That is, Raman scattering is measured.

The configuration for measuring the Raman spectrum is merely an example. You may comprise so that the Raman spectrum of each position of the thickness direction of the silica glass crucible 1 may be measured using things other than the said structure.

As described above, the crucible measuring apparatus according to the present embodiment includes the laser unit 21 and the Raman spectroscopic measuring unit 31. With such a configuration, the Raman spectrum of each position in the thickness direction of the silica glass crucible 1 on the end surface of the silica glass crucible 1 is acquired. That is, as shown in FIG. 18, the position of the laser unit 21 is adjusted so as to hit each position in the thickness direction of the silica glass crucible 1, and a Raman spectrum at each position in the thickness direction of the silica glass crucible 1 is acquired.

Here, it is known that in the Raman spectrum of silica glass, a plurality of peaks represented by a peak attributed to a planar four-membered ring and a peak attributed to a planar three-membered ring are measured. . Therefore, the Raman spectrum at each position in the thickness direction of the end surface of the silica glass crucible 1 similarly includes a plurality of peaks including a peak attributed to a planar four-membered ring and a peak attributed to a planar three-membered ring. have. On the other hand, when the measurement is actually performed, there may be a deviation in the Raman shift value of each peak at each position in the thickness direction of the silica glass crucible 1. That is, a plurality of structures may be included in the thickness direction of the silica glass crucible 1, and the plurality of structures are obtained by performing Raman measurement at each position in the thickness direction of the silica glass crucible 1 as described above. Can be measured.

When the Raman shift is different at each position in the thickness direction of the silica glass crucible 1 when the Raman spectrum is measured, the structure in the thickness direction of the silica glass crucible 1 is different. Deformation is likely to occur when pulling up the silicon single crystal using. Conversely, a Raman spectrum is measured at each position in the thickness direction of the silica glass crucible 1, and the silica glass crucible 1 having the same Raman shift (small difference) at each position in the thickness direction of the silica glass crucible 1 is obtained. By determining, it is possible to determine the silica glass crucible 1 that is not easily broken (not broken). Thus, the measurement of the Raman spectrum can also be used as one of methods for discriminating the silica glass crucible 1 that is difficult to break. When determining the silica glass crucible 1 that is difficult to break by measuring the Raman spectrum, for example, the Raman shift is the same in the light transmission layer or the light scattering layer (may be in the transparent layer or the bubble-containing layer). It is confirmed whether or not there is, or whether or not the Raman shift in the entire thickness direction is the same.

The measurement of the laser light scattering state described in the first and second embodiments and the measurement of the Raman spectrum described in this embodiment are performed simultaneously (or based on the measurement result of the laser light scattering state). It may be configured to perform measurement of a Raman spectrum (Raman scattering). Specifically, for example, the scattering state of laser light emitted from the inside of the silica glass crucible 1 is measured, and laser light is applied to each layer determined to have a different structure based on the measurement of the scattering state of the laser light. A laser beam for Raman excitation is applied under the measurement of the scattering state of the laser beam. Thereafter, after the laser beam for scattering measurement is stopped (when illumination light is irradiated by the illumination unit 4, the irradiation of illumination light is also stopped), and Raman measurement is performed. In other words, the light transmission layer and the light scattering layer are grasped based on the measurement result of the scattering state of the laser light, and the boundary between the light transmission layer, the light scattering layer, and the light transmission layer and the light scattering layer is determined based on the grasp result. Measure the Raman spectrum in the vicinity. Thus, by performing measurement by combining both methods, the structure of the layer in the thickness direction of the silica glass crucible 1 can be grasped easily and with higher accuracy. In addition, it is desirable to use lasers of different wavelengths for the laser for scattering measurement (laser light emitted from the laser light source 2) and the laser for Raman measurement (laser light emitted by the laser unit 21).

Subsequently, a crucible measuring method performed using the crucible measuring apparatus will be described.

Referring to FIG. 19, first, the laser unit 21 emits laser light from the end surface direction of the silica glass crucible 1 toward the end surface of the silica glass crucible 1 (S301). The laser light emitted from the laser unit 21 enters the end surface of the silica glass crucible 1 and then generates scattered light. Therefore, after the Rayleigh light is removed, the light is split and the split light is detected for each wavelength. For example, Raman scattering is measured by such a method (S302).

Thereafter, it is confirmed whether or not the laser light emission point is shifted in the thickness direction of the silica glass crucible 1 (S303). In the case of shifting, the laser light emission point is shifted in the thickness direction of the silica glass crucible 1 and then Raman scattering is measured again (Yes in S303). On the other hand, when it is not shifted (when the measurement in the thickness direction is finished), the Raman scattering measurement is finished (S303, No).

Thus, the crucible measurement method in the present embodiment performs Raman scattering measurement for each position in the thickness direction of the silica glass crucible 1. As a result, the structure of the layer in the thickness direction of the silica glass crucible 1 can be grasped based on the measurement result.

In addition, when manufacturing a silica glass crucible using a rotation mold method, a desirable silica glass crucible can be manufactured and realized also through the process of performing the Raman measurement mentioned above. Further, a silica glass crucible manufactured through a manufacturing process of a silica glass crucible having a configuration in which measurement of laser light in the thickness direction and Raman measurement is performed can have the same advantageous effects.

20 and 21 show the results of actually measuring the Raman spectrum at each position in the thickness direction of the silica glass crucible 1. FIG. 20 shows the result of measuring the Raman spectrum of each position in the thickness direction of the silica glass crucible 1 on the same end face of the silica glass crucible 1 as in FIGS. 6 and 10. FIG. 21 shows the result of measuring the Raman spectrum of each position in the thickness direction of the silica glass crucible 1 on the same end face of the silica glass crucible 1 as in FIGS. 7 and 11.

20 and FIG. 21, in order from the bottom, the Raman spectra of the inner surface side (transparent layer), the boundary between the inner surface and the middle, the middle, the boundary between the middle and the outer surface side, and the position of the outer surface side are measured. Show. For easy viewing, the results of the Raman spectra of FIGS. 20 and 21 are corrected so that the results do not overlap. Therefore, in the following, it is assumed that only the value of the Raman shift is a problem and the intensity is not seen.

Referring to FIG. 20, in the peak attributed to the plane four-membered ring (peak near 488 cm ⁻¹ ), the measurement results of the inner surface side and the boundary between the inner surface and the middle, the boundary between the middle, the middle and the outer surface side, the outer surface It can be seen that there is a large gap between the measurement results on the side. As shown in FIGS. 6 and 10, the silica glass crucible 1 measured in FIG. 20 has a light transmission layer and a light scattering layer, and the light scattering layer is determined to have a single structure. Layer. From the above, it can be considered that the result of Raman measurement and the measurement result of the scattering state in the thickness direction of the silica glass crucible 1 have a certain correlation. That is, the measurement result of the inner surface side and the boundary between the inner surface and the middle indicates the light transmission layer, and the measurement result of the middle, the boundary between the middle and the outer surface, and the measurement result on the outer surface side indicates the light scattering layer. Thus, it can be seen that the structure of the layer in the thickness direction of the silica glass crucible 1 can be grasped based on the result of Raman measurement.

Similarly, in FIG. 21, each boundary (inner surface) of a peak attributed to a plane four-membered ring (peak near 488 cm ⁻¹ ) and a peak attributed to a plane three-membered ring (peak near 602 cm ⁻¹ ) are shown. It can be seen that there is a shift in the value of the Raman shift at the boundary between the center and the middle, the boundary between the middle and the outer surface). As shown in FIGS. 7 and 11, the silica glass crucible 1 measured in FIG. 21 has a light transmission layer and a light scattering layer, and the light scattering layer is determined to be composed of a plurality of layers. Yes. This also shows that there is a certain correlation between the Raman measurement result and the measurement result of the scattering state in the thickness direction of the silica glass crucible 1.

In addition, the Raman spectrum of each point of the silica glass crucible 1 having a plurality of interfaces described above (inner surface side, interface 1, intermediate located on the outer surface side from the interface 1, interface 2, outer surface side) was measured. An example of the results is shown in Table 2. Table 2 shows an example of a peak attributed to a planar 4-membered ring at each point (peak near 488 cm ⁻¹ ) and a peak attributed to a planar 3-membered ring (peak near 602 cm ⁻¹ ).

In the case of the silica glass crucible 1 described above, as shown in Table 3, it can be seen that the respective structures are different on the inner surface side, the intermediate surface, and the outer surface side with the interfaces (interface 1 and interface 2) as boundaries. That is, it can be seen that the silica glass crucible 1 described above has a plurality of layer structures in the thickness direction with each interface as a boundary, and it is understood that the silica glass crucible 1 does not easily crack and does not break.

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.

DESCRIPTION OF SYMBOLS 1 Silica glass crucible 2 Laser light source 3 Camera part 4 Illumination part 21 Laser part 31 Raman spectroscopic measurement part 311 Rayleigh light removal filter 312 Spectrometer 313 Detector

Claims

A method for producing a silica glass crucible produced by a rotational mold method,
A cylindrical straight body having an opening at the upper end; a curved bottom; a corner that connects the side wall and the bottom and has a larger curvature than the bottom; and A method for producing a silica glass crucible, comprising a step of measuring a scattering state of each position in a thickness direction inside the side wall of the silica glass crucible of laser light incident in a silica glass crucible having a flat upper end.
The step of measuring the scattering state of the laser light is performed by emitting laser light from the inside of the silica glass crucible toward the thickness direction of the silica glass crucible, and entering the laser light of the silica glass crucible to be measured. The method for producing a silica glass crucible according to claim 1, wherein the scattering state of each position in the thickness direction inside the silica glass crucible side wall portion of the laser light is measured from the annular end face direction around the upper end opening of the portion.
The step of measuring the scattering state of the laser light is performed by irradiating a silica glass crucible with illumination light having a predetermined wavelength corresponding to the wavelength of the emitted laser light, and measuring the scattering state of the laser light under the illumination light irradiation. The method for producing a silica glass crucible according to claim 1 or 2.
The step of measuring the scattering state of the laser light,
A horizontal laser is emitted to the silica glass crucible,
The method for producing a silica glass crucible according to any one of claims 1 to 3, wherein a scattering state of each position in the thickness direction of the silica glass crucible of the horizontal laser incident on the silica glass crucible is measured.
The step of measuring the scattering state of the laser light,
A vertical laser is emitted to a silica glass crucible,
The method for producing a silica glass crucible according to any one of claims 1 to 4, wherein a scattering state at each position in the thickness direction of the silica glass crucible of a vertical laser incident on the silica glass crucible is measured.
The step of measuring the scattering state of the laser light,
The method for producing a silica glass crucible according to any one of claims 1 to 5, wherein the silica glass crucible is configured to emit laser light obliquely toward a depth direction of the silica glass crucible.
The step of measuring the scattering state of the laser light, the laser light is emitted over the entire circumference of the silica glass crucible at a predetermined predetermined interval,
The method for producing a silica glass crucible according to any one of claims 1 to 6, wherein each of the scattering states of the laser light corresponding to the emitted laser light is measured.
The step of measuring the scattering state includes:
The method for producing a silica glass crucible according to any one of claims 1 to 7, wherein laser light is incident on the silica glass crucible by emitting visible laser light.
The step of measuring the scattering state includes:
P-polarized light, which is polarized light whose direction of vibration of the electric field is parallel to the incident surface, is emitted to the silica glass crucible so that the incident angle is a Brewster angle.
The method for producing a silica glass crucible according to any one of claims 1 to 8, wherein the scattering state of each position of the p-polarized light incident on the silica glass crucible in the thickness direction of the silica glass crucible is measured.
The step of measuring the scattering state includes:
Measure the three-dimensional shape of the inner surface of the silica glass crucible,
The method for producing a silica glass crucible according to claim 9, wherein laser light is emitted to the silica glass crucible so that the incident angle becomes a Brewster angle based on the measurement result.
The step of measuring the scattering state of the laser light,
A laser beam is emitted from the end face direction of the silica glass crucible to each position in the thickness direction of the silica glass crucible,
The method for producing a silica glass crucible according to claim 1, wherein Raman scattering generated according to the emitted laser light is measured at each position as a scattering state of the laser light.
The step of measuring the scattering state of the laser light,
The laser light is emitted from the inside of the silica glass crucible toward the thickness direction of the silica glass crucible,
While measuring the scattering situation inside the silica glass crucible side wall of the silica glass crucible from the annular end surface direction around the upper end opening of the portion of the silica glass crucible to be measured is incident,
The method for producing a silica glass crucible according to claim 11, wherein the Raman scattering is measured based on the measurement result of the scattering state.
A cylindrical straight body portion having an opening at the upper end, a curved bottom portion, and a corner portion that connects the side wall portion and the bottom portion and has a larger curvature than the bottom portion, which are used for pulling a silicon single crystal. And a silica glass crucible in which the upper end of the straight body is formed flat,
The silica glass crucible has a light transmission layer that transmits laser light emitted to the silica glass crucible on the inner surface of the silica glass crucible.
The silica glass crucible according to claim 13, further comprising a light scattering layer that scatters laser light outside the light transmission layer.
The silica glass crucible according to claim 13 or 14, wherein the light transmission layer is a layer that transmits laser light without scattering.
The silica glass crucible according to any one of claims 13 to 15, wherein the light transmission layer is formed over the entire inner surface of the open end of the silica glass crucible.
The silica glass crucible according to any one of claims 13 to 16, wherein the light scattering layer is uniform in accordance with a reference in which scattered light of laser light is set in advance.
A value obtained by dividing the roundness of the shape of the boundary between the light transmission layer and the light scattering layer by the diameter of the silica glass crucible, which was measured based on the scattering state of the laser light emitted to the silica glass crucible, was determined in advance. It is comprised so that it may become smaller than a value. The silica glass crucible in any one of Claims 13 thru | or 17.
The silica glass crucible according to any one of claims 13 to 18, which has a plurality of interfaces in the thickness direction of the silica glass crucible.