JP3537522B2 - Crucible measurement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the thickness of a transparent quartz layer from the inner surface of a crucible used for producing single-crystal silicon by dissolving polycrystalline silicon to bubbles disposed inside the crucible. The present invention relates to a crucible measurement method for measuring dimensions.

[0002]

2. Description of the Related Art In general, as a quartz crucible for producing single crystal silicon, a transparent glass layer having a low bubble content (hereinafter referred to as a transparent layer) is provided on the inner surface side, and an opaque glass layer having a high bubble content is provided on the outside. (Hereinafter, referred to as an opaque layer) is used. In such a two-layer crucible, the heat transfer coefficient of the crucible wall changes due to the balance between the thickness of the transparent layer and the thickness of the opaque layer, which affects the performance of the crucible. Therefore, it is extremely important to measure these dimension values and control them to appropriate values.

Conventionally, as a method of measuring the thickness of the transparent layer of a crucible, a method of inspecting the thickness of the transparent layer by notching a part of the crucible and observing a cross section of the crucible with the naked eye, an ultrasonic wave method, or the like. A method of measuring the thickness of a transparent layer by scanning a probe in contact with the inner surface of a crucible has been adopted.

[0004]

However, in the case of the former method, since the inspection cannot be performed over the entire crucible, the thickness dimension of the entire transparent layer can be quantitatively grasped. In addition to being difficult, the destructive inspection has the disadvantage that the soundness of the crucible is impaired.
In this regard, the latter method can inspect the entire crucible and is a non-destructive inspection, so that the above-described inconvenience does not occur. However, it has the following separate problems.

That is, since the measurement by the ultrasonic probe is a contact-type measurement method in which the probe is brought into contact with the inner surface of the crucible, the inner surface of the crucible may be contaminated or damaged. Another problem is that it is difficult to automate the inspection. In other words, the inner shape of the crucible is slightly different for each crucible,
Because the inner surface shape cannot be accurately grasped in advance, the ultrasonic probe is separated from the inner surface of the crucible or pressed against the inner surface of the crucible with an excessive force during measurement, and the measurement error increases, or the crucible itself or The soundness of the ultrasonic probe may be impaired. Further, in the measurement by the ultrasonic probe, the measurement may be inaccurate due to the generation of an echo.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is possible to accurately measure the thickness of a transparent layer without contacting the inner surface of a crucible, and to easily automate the measurement. An object of the present invention is to provide a crucible measurement method that can be used.

[0007]

In order to achieve the above object, the present invention is provided with a laser light source for emitting laser light and an image pickup means for picking up reflected light of laser light from bubbles inside a crucible. Insert the measuring head inside the crucible, and the inner surface of the crucible of the laser light emitted from the laser light source
The distance between the incident positions at
After moving the measuring head to position the imaging means of the measuring head at a position separated from the inner surface of the crucible by a predetermined distance so as to match the axis of the measuring head with the normal of the inner surface of the crucible, Laser light is emitted from the direction inclined at a predetermined angle toward the crucible surface and bubbles are emitted.
Measuring the thickness dimension of the transparent layer on the inner surface of the crucible based on the position of the reflected light reflected by the imaging means.

In the above measuring method, before inserting the measuring head inside the crucible, the contour of the outer surface of the crucible is measured, and the positioning of the measuring head which does not interfere with the inner surface of the crucible estimated based on the contour of the outer surface of the crucible is determined. Setting the position is effective because the soundness of the crucible and the measuring head can be reliably ensured.

A method for measuring the contour of the outer surface of the crucible is activated while moving the contour measuring image pickup means having an axis perpendicular to the center line of the crucible in parallel with the center line of the crucible. If the two-dimensional position of the crucible outer surface in a plane perpendicular to the axis of the contour measuring imaging means is to be measured, the crucible outer surface can be easily and accurately adjusted using the symmetry of the crucible as a rotating body. This is effective because the contour can be measured.

Further, the measurement by the contour measuring image pickup means is performed at a plurality of positions in a plane including the center line of the crucible perpendicular to the axis thereof, and the plurality of measured two or more are measured.
2 different in straight line and curvature based on dimensional position data
If the contour of the outer surface of the crucible is obtained by approximating the type of arc, it is effective in that the speed of measurement can be improved.

[0011]

According to the method for measuring a crucible according to the present invention, a measuring head is inserted into the inside of the crucible, and the measuring head is moved so that the axis of the imaging means coincides with the normal of the inner surface of the crucible and the predetermined distance from the inner surface of the crucible. The laser light is emitted from the laser light source in a state where the laser light is positioned at a position separated by a distance of, so that the laser light is incident on the inner surface of the crucible at a predetermined inclination angle. The laser light incident on the transparent layer from the inner surface of the crucible is refracted on the inner surface and then travels to the bubbles inside, is reflected by the bubbles, is emitted again from the inner surface of the crucible, and is imaged by the imaging means.

In this case, the emission angle of the laser beam from the inner surface of the crucible can be changed according to the position of the bubble.
By calculating the emission angle based on the position of the imaged laser beam, the thickness of the transparent layer is measured. Therefore, according to the crucible measuring method, it is possible to measure the thickness of the transparent layer while keeping the measuring head in a state of non-contact with the inner surface of the crucible.

In the above measuring method, the contour of the outer surface of the crucible is measured before inserting the measuring head inside the crucible,
If the positioning position of the measuring head that does not interfere with the crucible inner surface estimated based on the contour of the crucible outer surface is set, contact between the measuring head inserted inside the crucible and the crucible inner surface is avoided. The soundness of the crucible and measuring head is maintained. Moreover, when the measuring head is inserted inside the crucible, it can be moved directly to the set positioning position, so the positioning position is determined while searching for a position that can avoid interference between the measuring head and the inner surface of the crucible. It is possible to dramatically improve the speed of measurement as compared with the case where the measurement is performed.

In the above measuring method, the method for measuring the contour of the outer surface of the crucible is operated while moving the contour measuring imaging means having an axis perpendicular to the center line of the crucible in parallel with the center line of the crucible. If the two-dimensional position of the outer surface of the crucible is measured in a plane including the center line and perpendicular to the axis of the imager for contour measurement, the contour of the outer surface of the crucible projected on the plane can be accurately measured. Will be measured. Further, since the crucible is a substantially accurate rotating body, it is possible to grasp a substantially accurate three-dimensional shape of the entire crucible by measuring the contour on one plane.

Further, the measurement by the contour measuring image pickup means is performed at a plurality of positions in a plane including the center line of the crucible perpendicular to the axis thereof, and a straight line and a curvature are calculated based on the plurality of measured two-dimensional position data. If the contour of the outer surface of the crucible is obtained by approximating two types of arcs different from each other, it is possible to minimize the number of measurements and improve the speed of measurement.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the method for measuring a crucible according to the present invention will be described below with reference to FIGS. The method of measuring a crucible according to the present embodiment, as shown in FIG.
First step of measuring the outer contour of crucible 1 (STEP
1) and a second step (STEP 2) of setting a plurality of measurement points for arranging a measurement head to be described later from the shape of the inner surface of the crucible 1 estimated based on the measurement result,
And a third step (STEP 3) of measuring the thickness of the transparent layer while positioning the measuring head on the inner surface of the crucible 1.

In a first step (STEP 1), a deviation dx from a predetermined measurement origin and a boundary between the background of each portion of the crucible 1 and a predetermined origin obtained by appropriate processing are measured. Then, the actual contour shape of the crucible 1 is grasped from the position coordinates of the external measuring device 3 at that time. Also, the deviation dx
Is a standard crucible 1 previously stored in a suitable storage means.
May be a deviation from the standard size of each part of the crucible 1 when referring to the outline (standard size).

As shown in FIG. 2, the outline of the crucible 1 is grasped by the height H, the outer diameter D, and the radii of curvature R ₁ and R ₂ of the bottom surface of the crucible 1. That is, the crucible 1, since the shape of a substantially accurate rotary body, if carried out in one vertical plane C ₀ through the center line 1a of the above dimensions, to grasp the outline of the entire crucible 1 I can do it.

In the first step (STEP 1), specifically, a data set in which the deviation dx and the position data thereof are associated with each other by the external measuring device 3 among the measuring devices 2 shown in FIG. Then, the above-mentioned respective dimensions H.
The calculation is performed by calculating D · R ₁ · R ₂ .

The external measuring device 3 is a device for measuring data for grasping the contour of the outer surface of the crucible 1, that is, the deviation dx in each part of the crucible 1 in association with its position. Is disposed outside the crucible 1 supported in an upright state. The external measuring device 3 includes a CCD camera 6 (contour measurement imaging means) having an axis 6a arranged in a horizontal direction, a vertical movement mechanism 7 for moving the CCD camera 6 in a vertical direction, a vertical movement mechanism 7, A horizontal movement mechanism 8 for horizontally moving the CCD camera 6 in parallel.

The vertical moving mechanism 7 and the horizontal moving mechanism 8
Are, for example, motors 7a and 8a and motors 7a and 8a
A ball screw (not shown) rotated around the axis by a nut and a nut (not shown) screwed to the ball screw, and fixed in a vertical direction (Z direction) or a horizontal direction (X direction).
A general linear moving mechanism composed of the sliders 7b and 8b which are moved to the right and left may be used. The base 7c of the vertical movement mechanism 7 is fixed to the slider 8b of the horizontal movement mechanism 8,
The vertical movement mechanism 7 itself can be translated in the horizontal direction together with the slider 8b that is moved by the operation of the horizontal movement mechanism 8. The CCD camera 6 is mounted on a slider 7a of the vertical movement mechanism 7, and the vertical movement mechanism 7 allows the CCD camera 6 to be translated in the vertical direction.

The vertical moving mechanism 7 and the horizontal moving mechanism 8 are provided with position detecting means (not shown). As the position detection means, any detection method such as a method using a direct detection method such as a magnet scale or a method for detecting the rotation angles of the motors 7a and 8a such as an encoder can be adopted.

The arithmetic means 4 uses the deviation dx from the measurement origin O measured by the external measuring device 3 and the position data Px and Pz in the vertical plane C to calculate the height H of the crucible 1 The radius D and the radius of curvature R ₁ · R ₂ of the bottom surface are calculated. For the radius of curvature R ₁ · R ₂ , an approximate calculation such as least square approximation is performed based on the obtained data set. calculate.

In this case, the measurement is performed by dividing the area so that the data sets on which the curvature radii R ₁ and R ₂ are calculated do not overlap, and each data area is determined based on the set of data sets for each area. The curvature radii R ₁ and R ₂ are measured.

When carrying out the first step (STEP 1), first, the CCD camera 6 should be arranged based on the standard outer diameter D of the crucible 1 stored in the storage means. A driving schedule of coordinates (Px, Pz) is created. The creation of the drive schedule may be performed by the calculating means 4 or may be stored in advance together with the standard dimensions.

Next, the vertical movement mechanism 7 and the horizontal movement mechanism 8 are operated based on the driving schedule. Thus, the CCD camera 6 is moved two-dimensionally in a vertical plane parallel to the center line 1a of the crucible 1, as shown in FIG. 3, while the axis 6a is kept horizontal. It will be accurately grasped by the detecting means. By operating the CCD camera 6 during the movement, the crucible 1 is imaged from one direction.

As a result, by repeating the imaging while moving the CCD camera 6 along the outer shape of the crucible 1, the contour shape of the crucible 1 projected on the vertical plane C is changed.
Is to be grasped. At this time, CCD
Measurement by the camera 6, several places in the height direction of the side wall portion of the crucible 1, several points for small curvature radius R ₂ moieties, several positions for large curvature radius R ₁ moiety, so as to be carried by each divided area ing.

Here, as shown in FIGS. 4 and 5, the deviation dx is used to move the position of the CCD camera 6 given by the coordinates (Px, Pz) on the contour of the crucible 1 so that the vertical movement mechanism 7 moves. And the boundary (surface) between the background of the crucible 1 imaged when the horizontal moving mechanism 8 is operated and the CCD camera 6
Is sampled as the amount of deviation from the measurement origin O.

Then, the deviation d thus measured is
x is transferred to the calculating means 4 together with the corresponding measurement position coordinate data (Px, Pz), and the height H, the outer diameter D, and the radii of curvature R ₁ and R ₂ that determine the contour of the crucible 1 are calculated. . Thereby, the contour shape of the cut surface when the crucible 1 is cut along one vertical plane C including the center line 1a is grasped, and the shape of the cut surface is rotated around the center line 1a to obtain a three-dimensional shape. The whole contour shape of the crucible 1 can be grasped.

In the second step (STEP 2), based on the outline shape of the crucible 1 grasped in this way, a rough measuring point is set by a measuring head in an internal measuring device described later. That is, when the contour of the outer surface of the crucible 1 is grasped, the crucible 1 is determined based on the standard thickness.
It is possible to estimate the shape of the inner surface, and further, considering the outer dimensions and the radius of gyration of the measuring head, a position where interference between the measuring head and the inner surface of the crucible 1 can be avoided,
That is, the movable region R of the measuring head can be estimated.

In the present embodiment, the movable region R satisfying the above condition is defined as an offset amount Δ from the contour of the outer surface of the crucible 1 as shown in FIG. A plurality of measurement points are set such that the measurement head is arranged in the movable area R offset inward. For example, a reference position for positioning is set at the tip of the measuring head, and a measuring point is appropriately set such that the tip is offset from the outer surface of the crucible 1 by an offset amount Δ inward. What should be done.

For the offset amount Δ, the crucible 1
What is necessary is just to store in a memory | storage means as what has a fixed value in each part. In addition, regarding the posture of the measuring head disposed at this measuring point, the crucible 1 at each measuring point estimated from the measured contour of the outer surface of the crucible 1 is also used.
What is necessary is just to set so that it may correspond to the normal line n direction of an inner surface.

The third step (STEP 3) is performed by the internal measuring device 9 of the measuring device 2 shown in FIG. The internal measuring device 9 is a device for measuring the thickness of the transparent layer 1 b on the inner surface of the crucible 1, and is disposed inside the crucible 1 and inserted into the crucible 1.
And a moving means 11 for moving the measuring head 10 with respect to the inner surface 1c of the crucible 1.

As shown in FIG. 6, the measuring head 10 has one CCD camera 13 (imaging means) and three laser light sources 14, 15, 16 fixedly mounted on a casing 12. ing. The CCD camera 13 and the laser light sources 14, 15, 16 are all fixed so as to have parallel axes.

One of the laser light sources 14, 15, 16 is a measuring laser light source 14 mainly used for measuring the transparent layer 1b on the inner surface of the crucible 1, and the other two are measuring heads. Positioning laser light sources 15 and 16 used when positioning the position 10 with respect to the inner surface of the crucible 1. As shown in FIG. 6, these laser light sources 14, 15
Mirror member 17, 18, 19 totally reflects the laser beam L ₁ · L ₂ · L ₃ emitted for the predetermined angle θ ₁ · θ ₂ · θ ₃ only in the direction which is tilted from - 16 are provided, respectively .

The mirror member 17 disposed on the optical axis of the measuring laser light source 14 converts the laser light L ₁ emitted from the measuring laser light source 14 into a plane parallel to the axis 13 a of the CCD camera 13. and it is adapted to bend in the C _1. The mirror member 18 arranged on the optical axis of the one positioning laser light source 15 is located within a plane C ₂ orthogonal to the plane C ₁ containing the laser light L ₁ emitted from the measuring laser light source 14. and it is adapted to bend the laser beam L ₂ emitted from the positioning laser light source 15 at. Further, the other positioning laser light source 1
The mirror section 19 disposed on the optical axis 6 bends the laser beam L ₃ in a plane C ₃ parallel to the plane C ₁ containing the laser beam L ₁ emitted from the measuring laser light source 14. It is made to let.

As a result, as shown in FIG. 6, when the measuring head 10 is accurately positioned at a predetermined measuring point, the normal line n of the inner surface 1c of the crucible 1 to be measured is measured.
In conjunction with the axis 13a of the CCD camera 13 is matched, the laser beam L _1, L _2, L ₃ from the three laser light sources 14, 15, 16, the vertices of a right triangle at the inner surface 1c of the crucible 1 The light is incident on three places and part of the light is reflected, and the reflected light is imaged by the CCD camera 13.

The moving means 11 is, for example, as shown in FIG.
In the example shown in FIG. 1, the turning table 20 for supporting the crucible 1 in a state of being opened vertically downward and rotating the crucible 1 around a vertically disposed central axis 1a, and a CCD provided on the measuring head 10 Axis 13a of camera 13
Drive shaft 21 (drive shaft) for oscillating the entire measurement head 10 in a state where is disposed in a vertical plane;
Linear drive shafts 22 and 23 for translating the entire measuring head 10 in parallel in two horizontal and vertical directions perpendicular to each other.
24.

The turning table 20 has a vertical center axis 1
a ring-plate-shaped table 20a rotatably supported about c, on which the crucible 1 is placed;
, A motor 20b for generating power for rotating the table 20a about its central axis 1c, and a table 2 for powering the motor 20b.
0a.
As the transmission mechanism 20c, for example, a general mechanism such as a pulley or a timing belt can be adopted.

The rotation drive shaft 21 has a swing arm 21a for fixing the measuring head 10 at one end, and a swing arm 21a.
The motor 21b is connected to the other end of the motor a through a speed reducer or the like (not shown). The motor 21b can swing the CCD camera 13 of the measuring head 10 in a vertical plane by rotating the swing arm 21a around a horizontal axis 21c.

In this embodiment, the axis 21c of the rotary drive shaft 21 is emitted from the measuring laser light source 14 while the measuring head 10 is accurately positioned with respect to the inner surface 1c of the crucible 1. Crucible 1 of light L ₁ and laser light L ₂ emitted from one positioning laser light source 15
It is provided so as to be parallel to a straight line A passing through incident positions P ₁ and P ₃ described later on the inner surface 1c.

The linear drive shafts 22, 23, 24 are constituted by, for example, a combination of three linear movement mechanisms capable of independently moving the measuring head 10 in X, Z, and Y3 directions orthogonal to each other. . This linear drive shaft 22,23.
In the example shown in FIG. 3, reference numeral 24 denotes a horizontal X-axis 22 fixed to an external structure (not shown), a vertical Z-axis 23 which is moved in the horizontal direction by the X-axis 22, and a Z-axis 23. And a Y-axis 24 for moving the measuring head 10 in a horizontal direction orthogonal to the X-axis 22.

The X-axis 22, Z-axis 23 and Y-axis 24 are fixed to, for example, a ball screw (not shown) rotated by motors 22a, 23a and 24a and a nut (not shown) screwed to the screw. Sliders 22b and 23
A general linear moving mechanism including a linear guide (not shown) that supports the sliders 22b, 23b, and 24b so as to be linearly movable can be employed.

The third step (STEP 3) further includes a positioning step (STEP 3a) for accurately positioning the measuring head 10 with respect to the inner surface 1c of the crucible 1, and actual measurement by the positioned measuring head 10. (STEP 3b).

In the positioning step (STEP 3a), first,
By operating the moving means 11, the measuring head 10
Is inserted into the crucible 1 and the above-mentioned second step (STEP 2)
Place at the measurement point set in. here,
Since this measurement point is set so as not to cause interference between the inner surface 1c of the crucible 1 and the measurement head 10,
There is no need to search for the presence or absence of interference, and the measuring head 10 can be arranged immediately.

In this case, the measuring point is provisionally set based on the measured contour of the outer surface of the crucible 1, so that the measuring head 10 arranged at the measuring point can be used as the actual crucible. It is necessary to correct the posture and distance of the inner surface 1c.

To correct the attitude of the measuring head 10 with respect to the inner surface 1a of the crucible 1, that is, to make the axis 13a of the CCD camera 13 provided in the measuring head 10 coincide with the normal line n of the inner surface 1a of the crucible 1 First, measuring head 1
The CCD camera 13, the measurement laser light source 14, and the positioning laser light sources 15 and 16 are operated. At this time, the CCD camera 13 has three laser light sources 14 and 15
It is assumed that the laser light L ₁ , L ₂ , L ₃ emitted from 16 is adjusted to capture the reflected light on the inner surface 1 c of the crucible 1.

Next, the incident position P _{1 of} the laser light L ₁ emitted from the measuring laser light source 14 on the inner surface 1 c of the crucible ₁ and one of the positioning laser light sources 15.
The incident positions P ₂ and P _{3 on the} inner surface 1 c of the crucible 1 of the laser beams L ₂ and L ₃ emitted from 16 are arranged on an arbitrary straight line A parallel to the axis 21 c of the rotary drive shaft 21. The moving means 11 is operated. Specifically, the measuring head 10
Axis 22 / Z axis 23 / Y axis 24
Is carried out by slightly moving.

Thus, for example, two laser beams L ₁
The incident positions P ₁ and P _{3 of} L _{3 on} the inner surface 1 a of the crucible 1 are
As shown in FIG. 7, when arranged on the straight line A, another 1
The incident position P _{2 of the two} laser beams L ₂ is
The image is picked up by the CCD camera 13 at a position deviated from the straight line B passing through the incident position P ₁ of the laser beam L ₁ from FIG.

Here, the laser beam L ₂ is incident on the inner surface 1c of the crucible 1 from an inclined direction. Accordingly, if rotating the measuring head 10 by operating the rotary drive shaft 21 to the straight line A direction, as shown in FIG. 8, only the incident position P ₂ to the laser beam L ₂ of the crucible 1 in the surface 1a is rotated Displaced according to the angle. In this case, the plane C ₂ including the laser beam L ₂ is parallel to the straight line A and the CCD camera 1
3 is arranged parallel to the axis 13a of the
₂ is C so that it can be displaced in a direction parallel to the straight line A.
It will be recognized by the CD camera 13.

[0051] Then, as shown by the solid line in FIG. 9, when the incident position P ₂ has been matched to the straight line B, the inner surface 1c of the crucible 1 in a portion to be measured to the axis 13a of the CCD camera 13 The normal n will be matched exactly. At this time, three laser beams L ₁ · L ₂ · L
Numerals ₃ are respectively made incident on three positions forming the vertices of a right triangle on the inner surface 1c of the crucible 1.

In this state, in order to correct the distance of the measuring head 10 to the inner surface 1c of the crucible 1, the measuring head 10
Along the direction of the axis 13 a of the CCD camera 13.
Move toward the inner surface 1c. Three laser beams L
_{Since 1} · L ₂ · L ₃ is inclined with respect to the axis 13a of the CCD camera 13, the measuring head 10 and the crucible 1
Depending on the change in the distance from the inner surface 1c, the incident positions P ₁ , P _2.
Distance dimension P ₃ is changed. Then, when the interval dimension becomes a predetermined dimension, the distance between the measuring head 10 and the inner surface 1c of the crucible 1 is accurately set, and the measuring head 1
0 positioning step for the crucible 1 inner surface 1a (ST
EP 3a) will be completed.

Next, the measurement step (STEP 3b) will be described. This measurement step (STEP 3b) measures the thickness of the transparent layer 1b based on the following measurement principle, and the positioning laser light sources 15 and 16 used in the above-described positioning step (STEP 3a) It stops the operation, and is performed only by the laser beam L ₁ emitted from the measurement laser light source 14.

That is, in FIG. 10, the incident angle α of the reflected light of the laser beam L ₁ emitted from the measuring laser light source 14 and reflected by the bubble 25 and captured by the CCD camera 13 is measured. By doing so, the thickness of the transparent layer 1b is calculated.

The CCD camera 13 has its axis 13a exactly coincident with the normal line n of the inner surface 1c of the crucible 1 by the above-mentioned positioning step (STEP 3a), and the lens 13b and the inner surface of the crucible 1 of the imaging surface 13c. The distances w and w + v from 1c are accurately set. In this state, the laser beam L ₁ is emitted from the measuring laser light source 14, the laser beam L ₁ is made incident at an inclined angle theta ₁ defined with respect to the normal n of the crucible 1 in the surface 1c, At the inner surface 1c of the crucible 1, a part thereof is reflected, and the rest is refracted and advanced into the transparent layer 1b.

The laser light L advanced into the transparent layer 1b
₁ is made to travel straight at an inclination angle φ with respect to a normal line n of the inner surface 1a of the crucible 1, and is reflected when reaching the air bubbles 25 disposed inside the transparent layer 1b, and is reflected to the normal line n. The light is again directed toward the inner surface 1c of the crucible 1 at an inclination angle γ, and is emitted to the outside of the transparent layer 1b. At this time, the laser light L ₁ is refracted again, and is imaged by the CCD camera 13 at an inclination angle α with respect to the normal line n of the inner surface 1 c of the crucible 1.

In such a case, the thickness T of the transparent layer 1b is expressed by the following equation. T = (X−w · tan α) / (tan φ + tan γ) (1) Here, X is the horizontal position between the incident position of the laser beam L ₁ on the inner surface 1 a of the crucible 1 and the axis 13 a of the CCD camera 13. Direction distance.

When the refractive index of air is n and the refractive index of the transparent layer 1b is n ′, the following relational expression holds. n · sin θ ₁ = n ′ · sin φ (2) n · sin α = n ′ · sin γ (3)

Therefore, the distance X, w, the refractive index n,
n ′ and the tilt angle θ ₁ are known, so that the CCD camera 1
By measuring the angle of incidence α of the reflected light of the laser beam L ₁ to 3, the thickness T of the transparent layer 1b would be calculated by the above equation (1) to (3). That is, these arithmetic expressions are stored in the arithmetic means 4, and the thickness T of the transparent layer 1b is calculated based on the incident angle α measured by the measuring head 10.

The incident angle α is calculated by α = tan ⁻¹ Δy, where Δy is the amount of deviation from the axis 13 a on the imaging surface 13 c of the CCD camera 13.

Such a positioning step (STEP 3a)
And the measurement step (STEP 3b) to the second step (STE
By performing the measurement at a plurality of measurement points set in P2), the thickness dimension of the transparent layer 1b is obtained for each portion of the inner surface 1c along a plane including the central axis 1a of the crucible 1. Each time the turning table 20 is rotated by a predetermined angle, the third step (STEP
By repeating 3), the inner peripheral surface 1 of the crucible 1
The thickness dimension of the transparent layer 1b is measured over the entire area c.

As described above, according to the method for measuring the crucible 1 according to the present embodiment, the contour of the outer surface of the crucible 1 is accurately measured in the first step (STEP 1), and the second step is performed based on the contour shape. Measurement head 10 by step (STEP 2)
Sets a plurality of measurement points that do not interfere with the inner surface 1c of the crucible 1, so that interference between the measuring head 10 inserted inside the crucible 1 and the inner surface 1c of the crucible 1 is reliably avoided. Therefore, the measurement head 10 can be quickly moved to the measurement point, and the time required for measurement can be reduced.

In the third step (STEP 3),
Since the measurement is performed in a state where the measuring head 10 is accurately positioned with respect to the inner surface 1c of the crucible 1, the transparent layer 1b
Is accurately measured. Moreover,
Since the measurement head 10 performs measurement without contacting the inner surface 1c of the crucible 1, the performance of the crucible 1 can be accurately grasped while maintaining the soundness of the crucible 1. further,
Since the measurement head 10 does not collide with the inner surface 1c of the crucible 1 and its operation is not limited, the measurement head 10 can be easily set to an optimal posture for measurement, and the measurement head 10 can be freely moved. Interference with the inner surface 1c of the crucible 1 hardly occurs even by the operation, so that the measurement can be easily automated.

In the first step (STEP 1), since only the contour shape projected on one vertical plane C including the center line 1a of the crucible 1 is measured, the symmetry of the crucible 1 is determined. By utilizing this, the contour shape of the entire crucible 1 can be quickly grasped. Further, since the cross-sectional shape of the bottom surface of the crucible 1 is approximated to an arc having two types of curvature radii R ₁ and R ₂ by an approximation method such as least squares approximation, the outline can be easily and quickly grasped with a small number of measurement points. Thus, the measurement time can be reduced.

In the third step (STEP 3), the laser beams L ₁ , L ₂ , L ₃ used for positioning the measuring head 10 on the inner surface 1c of the crucible 1 are moved with respect to the axis 13a of the CCD camera 13. Measuring head 1
In response to a change in the distance of 0 to the inner surface 1c of the crucible 1,
Is sensitively displaced the incident position P ₁ · P ₂ · P ₃ in the crucible 1 in the surface 1c of the laser beam _{L 1 · L 2 · L 3} , to quickly grasp the position of the measuring head 10 with respect to the crucible 1 in the surface 1c Can be. Therefore, the positioning of the measuring head 10 with respect to the inner surface 1c of the crucible 1 can be performed with high accuracy, and a collision state can be reliably avoided by quickly detecting the approaching state of the two.

Further, in this embodiment, the laser beam L _{2 of} one positioning laser light source 15 is referenced with respect to the plane C ₁ including the laser beam L ₁ emitted from the measurement laser light source 14.
In the plane C ₂ perpendicular to the reference plane C _1, the laser beam L ₃ reference plane C ₁ of the other positioning laser light source 16
Since the placing in the plane C ₃ parallel to, the incident position P ₁ to the laser beam L ₁ in the crucible 1 in the surface 1c of the measurement laser light source 14, one of the positioning laser light source 16 (15 )) The incident position P of the laser beam L ₃ (L ₂ )
₃ (P ₂ ) and a plane C ₂ (C ₃ ) parallel to a straight line A (B)
The laser light L ₂ (L ₃ ) of the other positioning laser light source 15 (16) is disposed in the measurement head 1.
The correction amount of the posture of 0 can be easily calculated.

That is, for example, as shown in FIGS. 8 and 9, the distance between a straight line A and a plane C ₂ parallel thereto is represented by L,
The deviation of the incident position P ₂ of the laser beam L ₂ from the straight line B in the direction parallel to the straight line A is Δx, the inclination angle of the laser beam L ₂ with respect to the axis 13 a of the CCD camera 13 is θ ₂ , and the measurement head 10 is corrected. If the amount (correction angle) is β ₁ , the correction amount β ₁
Is expressed as β ₁ = tan ^-1 (Δx / Ltan θ ₂ ). Further, the correction amount can be easily calculated for the other positioning laser light source 16 in the same manner.

Further, in this embodiment, the rotary drive shaft 21 is moved to the CC including the laser beam L ₃ from the positioning laser light source 16.
Since the measuring head 10 is provided so as to rotate about an axis 21 a orthogonal to a plane C ₃ parallel to the axis 13 a of the D camera 13, when correcting the attitude of the measuring head 10, The correction can be implemented directly by operation. Therefore, the correction can be performed quickly and accurately, and the thickness dimension of the transparent layer 1b on the inner surface of the crucible 1 can be measured accurately.

In the present embodiment, the moving means 11 for moving the measuring head 10 with respect to the crucible 1 in the internal measuring device 9 is replaced with a turning table 20 for rotating the crucible 1.
And three linear moving mechanisms 22, 23, and 24 and one rotary drive shaft 21, but the moving means 11 having an arbitrary shaft configuration can be employed instead. That is, as long as the moving means 11 has an axis configuration having at least five degrees of freedom with respect to the fixed crucible 1, various types of axis configurations such as an articulated type and a cylindrical coordinate type may be applied. .

In the above embodiment, the two positioning laser light sources 15 and.
Although 16 were arranged in directions orthogonal to each other, instead of this,
For example, the crucible 1 by dispersing the laser light L ₂ emitted from one positioning laser light source 15 into two from a predetermined direction
The light may be incident on the inner surface 1a.

Further, three laser beams L ₁ , L ₂ , L ₃ are emitted from the measurement laser light source 14 and the two positioning laser light sources 15, 16. Laser light L ₁ emitted from one laser light source 14
May be divided into three and irradiated. In this case, all the laser light L ₁ · L ₂ · L ₃ is irradiated at the time of positioning, when measurement, so as to irradiate only one of the laser beams L _1, for example, may be used shutter or the like.

Each of the positioning laser light sources 15 and 16
The incident direction of the laser light L ₂ · L ₃ from the other two laser light L ₁ · L ₃ or the incident position P ₁ · L ₂ of the laser light L ₁ · L _2.
A plane C ₂ · C ₃ parallel to a straight line AB connecting P ₃ and P ₁ · P ₂
Although it is set so that it is disposed inside, the positioning of the measurement head 10 can be performed even if the light is incident from a different direction. However, it is preferable to set as in the above embodiment in that the calculation of the correction amount can be made easy.

Further, the two positioning laser light sources 15 and 16 are arranged in a direction orthogonal to each other with reference to the measuring laser light source 14, but the present invention is not limited to this. One positioning laser light source 15 (16) The other laser light sources 14 and 16 (15) may be arranged on the basis of. Also, as the incident positions P ₁ , P _2, and P ₃ of the _three laser light sources L ₁ , L _2, and L _{3 on} the inner surface 1 c of the crucible 1, the light is incident on three different points that are the vertices of a right triangle. In addition, the light may be incident on any three different places, except when the light is arranged on a straight line.

Further, by adding a driving mechanism for rotating and moving the laser light source and the mirror member in the fixed state, highly accurate positioning and measurement can be performed step by step. In particular, by applying the present invention to a measurement laser light source, it is possible to detect rare bubbles existing in the transparent layer 2b and accurately measure the bubble content and the like.

[0075]

As described above in detail, in the method for measuring a crucible according to the present invention, the measuring head is inserted inside the crucible,
After positioning the imaging means at a position separated by a predetermined distance from the inner surface of the crucible in such a manner that its axis coincides with the normal of the inner surface of the crucible, the inner surface of the crucible is inclined at a predetermined angle with respect to the axis of the imaging means. Since the thickness of the transparent layer on the inner surface of the crucible is measured based on the position of the reflected light imaged by the imaging means, the thickness of the transparent layer on the inner surface of the crucible is measured without contact. It has the effect of being able to.

Therefore, the measuring head can be freely moved to secure optimum measuring conditions, and highly accurate measurement can be performed. Further, the soundness of the inner surface of the measuring head and the crucible is not impaired.

Before inserting the measuring head inside the crucible, the contour of the crucible outer surface is measured, and the positioning position of the measuring head which does not interfere with the crucible inner surface estimated based on the crucible outer surface is set. So that
In addition to the above effects, there is an effect that the measurement head can be quickly disposed at the measurement point where the thickness measurement of the transparent layer on the inner surface of the crucible is to be performed, and the time required for measurement can be reduced.

In this case, the positioning position of the positioning head is set by measuring the outer surface of the crucible, because measurement can be performed more easily and with higher precision than measuring the shape of the inner surface of the crucible. For example, the contour measurement imaging means having an axis arranged so as to be orthogonal to the center line of the crucible is operated while moving in parallel to the center line of the crucible, and includes the center line and is perpendicular to the axis of the contour measurement imaging means. By measuring the two-dimensional position of the contour of the crucible outer surface in the plane, the contour can be grasped very easily.

Furthermore, if the symmetry of the crucible, which is an almost accurate rotating body, is used, the above-described measurement is performed on one plane, so that the three-dimensional outline can be easily grasped, and the measurement can be performed efficiently. There is an advantage that can be performed. Furthermore, the measurement by the contour measurement imaging means is performed at a plurality of locations in a plane including the center line of the crucible perpendicular to the axis, and based on a plurality of measured two-dimensional position data, two lines having different straight lines and different curvatures are measured. If the outline of the crucible outer surface is obtained by approximating the type of arc, there is an effect that the outline of the crucible outer surface can be more efficiently grasped based on the minimum number of measurement points.

[Brief description of the drawings]

FIG. 1 is a view showing a flowchart according to an embodiment of a crucible measuring method according to the present invention.

FIG. 2 is a longitudinal sectional view showing a sectional shape of the crucible measured according to FIG.

FIG. 3 is a perspective view showing an example of a measuring device that performs the measuring method of FIG.

FIG. 4 is a schematic diagram for explaining measurement of an outline of a crucible outer surface by an external measurement device of the measurement device of FIG. 1;

FIG. 5 is a diagram showing an example of an image based on the measurement in FIG. 3;

6 is a perspective view showing a measuring head of an internal measuring device of the measuring device of FIG. 2;

FIG. 7 is a view for explaining a case where the measuring head of FIG. 6 is positioned on the inner surface of the crucible.

8 is an explanatory diagram for deriving a correction amount of a posture of the measuring head of FIG. 6 with respect to an inner surface of a crucible.

9 is a diagram illustrating the incident positions of the respective laser beams in a state where the posture of the measuring head of FIG. 6 with respect to the inner surface of the crucible is corrected.

10 is a diagram for explaining the principle of measuring the thickness dimension of the transparent layer on the inner surface of the crucible by the measuring head of FIG.

[Explanation of symbols]

1 crucible 1a centerline 1b transparent layer 1c in the surface 6 CCD camera (contour measuring image pickup means) 6a axis 10 measuring head 13 CCD camera (imaging means) 13a axis 14, 15, and 16 a laser light source 25 bubbles L _1, L _2, L ₃ laser light n normal

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshiaki Kasai 5-14-3 Ibarjima, Akita City, Akita Mitsubishi Materials Real Quartz Co., Ltd. Akita Plant (56) References JP-A-3-86249 (JP, A) JP-A-63-314403 (JP, A) JP-A-4-34305 (JP, A) JP-A-1-148782 (JP, A) JP-A-4-119986 (JP, A) JP-A-6-191986 ( JP, A) JP-A-8-278117 (JP, A) JP-A-9-49710 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C30B 1/00-35/00 C03B 20/00 G01B 11/06

Claims (4)

(57) [Claims] 1. A measuring head having a laser light source for emitting laser light and an imaging means for imaging reflected light of laser light in bubbles inside a crucible is inserted inside the crucible, and the measuring head is emitted from the laser light source. Laser light on the inner surface of the crucible
Measurement so that the distance between the incident positions
By moving the head, the imaging means of the measuring head is positioned at a position separated from the inner surface of the crucible by a predetermined distance so that its axis coincides with the normal of the inner surface of the crucible, and thereafter, with respect to the axis of the imaging means. a laser beam is emitted toward the crucible surface in the direction which is inclined at a predetermined angle, bubbles odor
Measuring the thickness of the transparent layer on the inner surface of the crucible based on the position of the reflected light reflected by the imaging means and imaged by the imaging means. 2. Before inserting the measuring head inside the crucible, the contour of the outer surface of the crucible is measured, and a positioning position of the measuring head which does not interfere with the inner surface of the crucible estimated based on the contour of the outer surface of the crucible is set. 2. The method according to claim 1, wherein
The crucible measurement method described. 3. A method for measuring the contour of an outer surface of a crucible comprises operating a contour measuring imaging means having an axis perpendicular to the center line of the crucible while moving the imaging means in parallel with the center line of the crucible. The method for measuring a crucible according to claim 2, wherein the two-dimensional position of the outer surface of the crucible is measured in a plane perpendicular to the axis of the contour measurement imaging means. 4. The method according to claim 1, wherein the measurement by the contour measurement imaging means is performed at a plurality of locations in a plane including the center line of the crucible perpendicular to the axis thereof, and a straight line and a straight line are determined based on the plurality of measured two-dimensional position data. 4. The crucible measuring method according to claim 3, wherein an outline of the crucible outer surface is obtained by approximating two types of arcs having different curvatures.