JP2883667B2 - Single crystal ingot crystal orientation measurement system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a crystal orientation measuring device for measuring the crystal orientation of a cylindrical single crystal ingot by X-ray diffraction.

[Prior Art] When a Si single crystal ingot for manufacturing a Si wafer is pulled up from a crucible, it has a substantially cylindrical shape as shown in FIG. 8 (a), and both ends are sharp. I have. This raw ingot 10 is cut at both ends,
As shown in FIG. 8 (b), a two-end cut ingot 11 having an end face 13 and an unprocessed outer peripheral face 12 is obtained. Thereafter, as shown in FIG. 8 (c), the orientation flat surface 16 (hereinafter, abbreviated as the orientation flat surface) is cut and the outer peripheral surface 18 is ground to form the processed ingot 14.

Incidentally, the Si ingot is manufactured so as to have a predetermined crystal orientation. For example, the crystal orientation [100] is made to coincide with the axial direction of the ingot. Alternatively, the crystal orientation [11
1] and [511] may be matched. Here, the crystal orientation [100] is the direction of the normal to the lattice plane (100).

Also when processing the orientation flat surface 16, the normal line of the orientation flat surface is made to coincide with a specific crystal orientation. For this purpose, the outer peripheral surface of the ingot 11 at both ends shown in FIG.
The ingot 11 is rotated about an axis while irradiating X-rays 12 to search for a desired crystal orientation, and one end face 13 is marked for orientation flat processing.

The processed ingot 14 is inspected by X-ray diffraction measurement as to how much the orientation flat surface 16 and the outer peripheral surface 18 deviate from a predetermined crystal orientation. This will be described with reference to FIG.

To measure the angle δ1 between the normal direction 20 of the orientation flat surface 16 and a specific crystal orientation (for example, a crystal orientation [100]), an X-ray
22 is irradiated onto the orientation flat surface 16 at an incident angle θ, and its diffracted X-ray is measured by a detector at the angle θ (actually, the orientation flat surface 16 is placed on a reference surface and Often measured on the outer surface of the side). Angle θ is Si (10
0) Set the diffraction angle of the plane. Then, the relative position between the X-ray source and the X-ray detector is fixed, and the entire X-ray optical system is
The above-described shift angle δ1 can be found by searching for the angular position of the diffraction peak while rotating about 21.

In order to inspect the angle δ2 between the central axis 24 of the outer peripheral surface 18 and the crystal orientation [100], in a plane perpendicular to the end surface 13, X
A line 26 is irradiated on the end face 13 at an incident angle θ, and the diffracted X-ray is measured by a detector at the angle θ. Angle θ is Si (10
0) Set the diffraction angle of the plane. Then, the relative position between the X-ray source and the X-ray detector is fixed, and the entire X-ray optical system is
The above-described shift angle δ2 can be found by searching for the angular position of the diffraction peak while rotating about 25. Actually, since the grating plane (100) is not always inclined in the direction including the X-ray optical system, the center axis
The ingot is rotated around, for example, 90 degrees, and the shift angle δ2 is measured in the same manner, and the true shift angle δ2 and its inclination direction are obtained from the plurality of measurement results.

In this specification, a lattice plane equivalent to the (100) plane,
For example, (010) and (001) are all called (100) planes, and they are treated equally. Since the crystal structure of the Si single crystal has a diamond type structure belonging to a cubic system, if the orientation flat surface 16 is parallel to the (100) plane, the end face 13 is also parallel to the (100) plane.

[Problems to be Solved by the Invention] As described above, before measuring the crystal orientation of the processed ingot, (a) X-ray diffraction measurement for marking for processing the orientation flat surface, and (b) X-ray diffraction measurement for inspecting the crystal orientation with respect to the processed orientation flat surface; and (c) X for inspecting the crystal orientation with respect to the processed outer peripheral surface.
X-ray diffraction measurement is required. In the above-described measurements (a) and (b), it is necessary to arrange the axis of the ingot perpendicular to the plane including the X-ray optical system. In the above-described measurement (c),
It is necessary to arrange the axis of the ingot parallel to the plane including the X-ray optical system. Therefore, if the X-ray optical system is arranged, for example, in a horizontal plane, the above-mentioned (a)
In the measurement of (b), the ingot must be set upright. Conversely, if the X-ray optical system is arranged in a vertical plane, the ingot must be set upright in the above measurement (c). In any case, the work of measuring the ingot vertically is required.

Incidentally, currently manufactured Si single crystal ingots have a nominal diameter of 4 to 8 inches and a length of 50 to 10 inches.
It is about 00mm, and one heavy object weighs several tens of kilograms. It is difficult for an operator to stand such a heavy ingot vertically, and there is a great risk of damaging the ingot. Also,
If a long ingot is set up vertically and X-ray diffraction measurement is to be performed on its end face, the X-ray optical system is arranged at a very high position from the floor surface, and workability is extremely deteriorated.

An object of the present invention is to provide a crystal orientation measuring apparatus capable of performing the above-described measuring operations (a) to (c) while holding an ingot horizontally.

[Means for Solving the Problems] In order to achieve the above object, a crystal orientation measuring apparatus according to the present invention comprises a first X-ray diffraction measuring section having an optical axis in a plane perpendicular to the axis of an ingot. A second X-ray diffraction measuring unit having an optical axis in a plane parallel to the axis of the ingot, a pair of rotatable support rollers for supporting the outer peripheral surface of the ingot horizontally disposed from below, A follow-up movement mechanism for moving the first X-ray diffraction measurement unit in the vertical direction by following irregularities on the outer peripheral surface of the ingot; and rotating the second X-ray diffraction measurement unit about a vertically extending axis. A rotation mechanism.

[Operation] In the above-described measurements (a) and (b), the first X-ray diffraction measurement unit is used, and in the above-described measurement (c), the second X-ray diffraction measurement unit is used. Thus, all the crystal orientation measurements can be performed with the ingot placed horizontally.

Embodiment Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a basic configuration diagram of an embodiment of the present invention. The ingot 28 (actually, either the both-end cut ingot 11 in FIG. 8B or the processed ingot 14 in FIG. 8C) is supported by rotatable support rollers 30 and 31. Are arranged horizontally. However, when measuring the crystal orientation with respect to the orientation flat surface of the processed ingot, the orientation flat surface is placed on the reference surface 32.

This apparatus has two systems of X-ray diffraction measurement units. The first X-ray diffraction measuring section 34 is arranged in a plane perpendicular to the axis of the ingot 28 (that is, in a vertical plane). X-rays from the X-ray source 38 are diffracted on the outer peripheral surface of the ingot 28 and are converted to an X-ray detector.
Detected at 40. The second X-ray diffraction measurement unit 36 is an ingot
It is located in a plane parallel to the 28 axes (ie in a horizontal plane). X-rays from the X-ray source 42 are diffracted at the end face of the ingot 28 and detected by the X-ray detector 44.

The marking guide 46 is used when a processing line of the orientation flat surface is drawn on the end surface of the ingot 28 with a marker pen or the like, and the guide surface 47 is parallel to the reference line 35 of the first X-ray diffraction measurement unit 34. Has become.

Hereinafter, the detailed structure of each part will be described together while explaining how to use this device. The description will be made in the following order.

I. Marking work for orientation flat processing on both ends cut and ingot b. Measurement of crystal orientation with respect to the orientation flat surface of the processed ingot c. Measurement of crystal orientation with respect to the outer peripheral surface of the processed ingot Marking operation for orientation flat surface processing on both ends cut and ingot The marking operation is performed by placing both ends cut and ingot 11 of FIG. 8B on the support rollers 30 and 31 of FIG. FIG. 2 is a front view of the apparatus of FIG. 1 when performing this operation. X-rays from the X-ray source 38 of the X-ray tube 48 have an incident angle θ
To hit the outer peripheral surface of the ingot 11 with an X-ray detector
40 is also arranged at an angle θ with respect to the reference line 35. Angle θ is determined by the type of lattice plane 51 that should be parallel to the orientation flat plane (for example, (100) plane, (111) plane, (511) plane, etc.). In this apparatus, when the type of the lattice plane 51 is designated, the X-ray tube 48 and the X-ray detector 40 are automatically rotated along the base 50 to automatically set the angle θ. When the angle θ is set, X-ray diffraction measurement is performed while rotating the ingot 11, and the ingot 11 is stopped when the detected intensity becomes maximum. Then, the marking guide 46 shown in FIG. 1 is pressed against the end surface of the ingot, and a processing line on the orientation flat surface is drawn with a marker pen or the like. The marking guide 46
The height can be adjusted according to the diameter of the ingot.

FIG. 3 is a rear view of the apparatus shown in FIG. 1 showing a mechanism for rotating the ingot 11. Ingot 11 is a drive roller
It is rotationally driven by 52 and 54. The drive rollers 52, 54 are driven by a handle 58 via a toothed belt 56. The handle 58 and the drive rollers 52 and 54 are rotatably mounted on a plate 60 that can move up and down. When rotating the ingot 11, the plate 60 is lowered, and the drive rollers 52 and 54 are brought into contact with the ingot 11, and then the handle 58 is turned.

FIG. 4 is a front view of the apparatus shown in FIG. 1, showing a mechanism for following irregularities on the outer peripheral surface of the ingot 11. The actual cut at both ends of the ingot 11 has irregularities because the outer peripheral surface is unprocessed. In order for the X-ray irradiation point to follow the irregularities on the outer peripheral surface, it is necessary to move the base 50 up and down. The motor 62 rotates a screw 66 via a gear transmission 64 to move the upper and lower parts 68 up and down. The upper and lower parts 68 are fixed to the base 50. Therefore, the base 50 can be moved up and down by rotating the motor 62.

A light source 70 and an optical sensor 72 are fixed to the base 50. The optical axis of this optical sensor system passes through the X-ray irradiation point. The optical sensor 72 has a light receiving element 74, the output of the light receiving element 74 is compared with a predetermined reference value, and the difference is output. When the outer peripheral surface of the ingot 11 exactly matches the height of the optical axis of the optical sensor system, half of the light from the light source 70 is blocked by the ingot 11 and half reaches the light receiving element 74. At this time, the output of the light receiving element 74 becomes equal to the reference value. When the outer peripheral surface of the ingot 11 is higher than the X-ray irradiation point (that is, higher than the optical axis of the optical sensor system), the output of the light receiving element 74 decreases, and the difference from the reference value becomes a negative value. Based on this information, the motor 62 rotates and the base
Raise 50. The base 50 will rise until the X-ray irradiation point coincides with the outer peripheral surface of the ingot 11. By such feedback control, the X-ray irradiation point always follows so as to coincide with the outer peripheral surface of the ingot 11.

B. Measurement of the crystal orientation of the processed ingot with respect to the orientation flat surface The ingot on which the orientation flat surface is marked as described above is subjected to the cutting process of the orientation flat surface and the grinding process of the outer peripheral surface, and becomes a processed ingot. FIG. 5 is a front view of the apparatus of FIG. 1 when measuring the deviation of the crystal orientation from the orientation flat surface of the processed ingot.

To perform this measurement, first, the support rollers 30 and 31 are opened on both sides, and the orientation flat surface of the ingot 14 is placed on the reference surface 32. Then, the X-ray irradiation point of the first X-ray diffraction measurement unit 34 is adjusted to the outer peripheral surface of the ingot 14. X to reference line 35
The angle θ between the tube 48 and the X-ray detector 40 is fixed to be the same as the value set in the above-mentioned orientation flat surface marking operation. In order to measure the deviation angle between the processed orientation flat surface and the target grating surface 51, a position where the X-ray detection intensity is maximized is searched for while rotating the base 50 around the X-ray irradiation point. The rotation angle δ at the maximum is the normal of the orientation flat surface,
The deviation angle from the crystal orientation of the target lattice plane 51 is obtained.

C. Measurement of Crystal Orientation on Outer Peripheral Surface of Processed Ingot Next, the crystal orientation on the outer peripheral surface of the processed ingot is measured. To this end, as shown in FIG. 6, the ingot 14 is lifted from the reference surface 32 by moving the support rollers 30 and 31 inward. Then, as shown in FIG.
Rotate 14 so that the orientation flat 16 faces up. FIG. 7 is a perspective view showing in detail the second X-ray diffraction measuring section 36 of the apparatus shown in FIG.

What should be detected in this measurement is the outer peripheral surface of ingot 14.
This is the difference between the central axis of 18 and the crystal orientation of the target lattice plane.
First, the X-ray tube 76 and the X-ray detector 44 are moved with respect to the base 78, and both are set at a predetermined angle with respect to the reference line 77. Is naturally adjusted to the diffraction angle of the grating surface to be measured. After the X-ray tube 76 and the X-ray detector 44 are fixed to the base 78 in this way, the entire base 78 is rotated around the axis 79 to search for a position where the diffraction intensity is maximized. To explain the specific work, turn the handle 84,
The base 78 rotates via the worm 80 and the worm gear 82. The rotation angle of the worm 80 is detected by the encoder 86,
This is converted into a rotation angle of the base 78 and displayed on the display 88. The X-ray detection intensity is displayed on a rate meter 90 connected to the X-ray detector 40. The worker uses the rate meter 90
The operator turns the handle 84 while watching the display, stops the handle 84 at the position where the X-ray detection intensity is maximum, and reads the rotation angle of the base 78 at that time on the display 88. This value is the shift angle of the lattice plane.

Next, the ingot 14 is rotated 90 degrees clockwise about the axis, and the orientation flat surface 16 is disposed on the right side, and the deviation angle is measured in the same manner. Further, the misalignment angle when the orientation flat surface 16 is arranged on the left side is also measured. Based on these deviation angles, the true deviation angle between the direction of the central axis of the outer peripheral surface 18 and the crystal orientation of the lattice plane is determined.

Although the above embodiment has been described with reference to a Si single crystal ingot as an example, the present invention can be applied to other single crystal ingots.

[Effects of the Invention] As described above, the present invention has a first X-ray diffraction measurement unit having an optical axis in a plane perpendicular to the axis of the ingot, and an optical axis in a plane parallel to the axis of the ingot. Since it has the second X-ray diffraction measurement unit, all of the marking work for processing the orientation flat surface, the measurement of the crystal orientation on the processed orientation flat surface, and the measurement of the crystal orientation on the processed outer peripheral surface, It can be carried out with the ingot placed horizontally, and the workability is extremely good.

[Brief description of the drawings]

FIG. 1 is a perspective view of a basic configuration of an embodiment of the present invention, FIG. 2 is a front view showing a marking work for processing an orientation flat surface, FIG. 3 is a rear view showing a rotating mechanism of an ingot, and FIG. FIG. 5 is a front view showing a mechanism for causing the X-ray diffraction measurement section to follow the outer peripheral surface of the ingot. FIG. 5 is a front view showing an operation for measuring the crystal orientation with respect to the orientation flat surface. FIG. FIG. 7 is a front view, FIG. 7 is a perspective view showing an operation of measuring a crystal orientation with respect to an outer peripheral surface, FIG. 8 is an explanatory view showing a processing procedure of an ingot, and FIG. 9 is a perspective view explaining a crystal orientation measurement of the ingot. . 11, 14, 28 ... ingot 34 ... first X-ray diffraction measurement unit 36 ... second X-ray diffraction measurement unit

Claims (1)

(57) [Claims] 1. The crystal orientation of a cylindrical single crystal ingot is X
In a crystal orientation measuring apparatus for measuring by X-ray diffraction, a first X-ray diffraction measuring section having an optical axis in a plane perpendicular to the axis of the ingot; and a second X-ray diffraction measuring section having an optical axis in a plane parallel to the axis of the ingot. 2, an X-ray diffraction measurement unit, a pair of rotatable support rollers for supporting the outer peripheral surface of the ingot horizontally disposed from below, and the first X by following irregularities on the outer peripheral surface of the ingot. A crystal orientation measuring device, comprising: a follow-up moving mechanism that moves a X-ray diffraction measurement unit in a vertical direction; and a rotation mechanism that rotates the second X-ray diffraction measurement unit about an axis extending in a vertical direction.