JP2016211916A - Apparatus and method for measuring x ray crystal orientation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for measuring X ray crystal orientation, capable of simply detecting a diffracted X ray to measure crystal orientation even when the surface to be measured of a single crystal sample has a large shift angle to a crystal plane other than a deviation angle.SOLUTION: An apparatus for measuring the crystal orientation of a surface to be measured of a single crystal sample using an X ray comprises: X ray irradiation means for irradiating the surface to be measured of the single crystal sample with the X ray; sample rotation means capable of passing through the center of the single crystal sample and rotating around a rotation axis parallel to the surface to be measured and having a rotation axis direction perpendicular to a flat surface including the optical axis of the X ray incident on the surface to be measured and the normal of the surface to be measured having the incident optical axis; X ray detection means for detecting the diffracted X ray of the X ray irradiated on the surface to be measured of the single crystal sample from the X ray irradiation means; and movable means for moving the X ray detection means in a direction perpendicular to the flat surface including the optical axis and the normal.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an X-ray crystal orientation measuring apparatus and an X-ray crystal orientation measuring method for measuring a crystal orientation of a semiconductor silicon wafer, a compound semiconductor wafer, or quartz crystal with X-rays.

  Single crystals, such as semiconductor silicon wafers and compound semiconductor wafers, have crystal orientations of cut planes (that is, crystal planes whose actual cut planes are (100), (111), (110), (511), etc.) It is measured how much it is tilted from (sometimes called a surface), and the cutting angle is adjusted to match this with the standard value. An outline of this crystal orientation measurement method will be described with reference to FIGS.

FIG. 8 shows a principle diagram of crystal orientation measurement by X-ray. The incident angle θ formed by the just crystal plane of the sample single crystal and the incident X-ray and the reflection angle θ formed by the just crystal plane and the reflected (diffracted) X-ray are both obtained from the Bragg reflection conditions expressed by the following equation (1). The incident X-rays emitted from the X-ray source (X-ray irradiating means 11) are reflected (diffracted) by the just crystal plane of the sample single crystal 13 and become the X-ray detector (X It is detected by the line detection means 12).
2d · sin θ ′ = nλ (1)
(Where d: spacing between just crystal planes, λ: wavelength of X-ray, n: natural number)
Further, the cut surface of the sample single crystal does not necessarily coincide with the just crystal surface, and the difference φ between the cut surface and the just crystal surface is called a deviation angle (see FIG. 8).

  As described above, the cut surface (surface to be measured) of the sample single crystal does not necessarily coincide with the just crystal plane. As shown in FIG. 9, it is common to have a deviation angle φ and a tilt angle ψ. In FIG. 9, when X-rays enter the sample single crystal within the XZ plane, the tilt around the Y axis of the just crystal plane is called the deviation angle, and the tilt around the X axis perpendicular to this is called the tilt angle.

  An outline of an X-ray crystal orientation measuring apparatus is shown in FIG. 10 and is illustrated in FIG. 11 as a three-view diagram ((a) top view, (b) front view, (c) side view). The X-ray crystal orientation measuring device is also called an X-ray goniometer. The sample single crystal 13 is rotated about the (vertical) rotation axis A by the sample rotating means 14 of FIG. 10, and the direction of the measured surface of the sample single crystal can be adjusted to an angle satisfying the Bragg reflection condition described above.

  When the sample single crystal has only the deviation angle φ 1, that is, as shown in the top view of FIG. 11A, the just crystal plane is inclined with respect to the cut surface of the sample single crystal when viewed from above (or below). 11C, when viewed from the side, when not tilted, the X-ray diffracted X-ray incident on the cut surface of the sample single crystal 13 from the horizontal direction is incident X-ray. And enters the X-ray detection means 12 provided in the horizontal plane. As shown in FIGS. 11B and 11C, the diffracted X-ray does not deviate in the vertical direction of the X-ray detection unit 12. FIG. 11B illustrates a case where a wafer having a notch 15 is used as a sample single crystal.

JP-A-5-312736 JP 2005-265502 A JP 2006-329821 A

  When the sample single crystal has a large tilt angle in addition to the deviation angle, as shown in FIG. 12, the diffraction angle causes the diffracted X-ray to deviate upward (or downward) from the X-ray detection means 12. Therefore, the crystal orientation in this direction cannot be measured (see the front view of FIG. 12B and the side view of FIG. 12C).

  On the other hand, Patent Document 1 uses a curved X-ray detector and a half shutter to capture diffracted X-rays from a measured surface of a sample single crystal having a tilt angle. Even with this technique, it is possible to measure the crystal orientation of the surface to be measured with a tilt angle, but the curved X-ray detector itself is not necessarily a general one, and there is a hurdle when putting this technique to practical use. Is very expensive.

  Further, Patent Document 2 is characterized in that a two-dimensional detector is used for detecting diffracted X-rays, and has an advantage that a deviation angle and a tilt angle can be measured by one measurement. However, in order to detect an X-ray diffraction spot from a crystal having a large tilt angle, a large two-dimensional detector must be used, collimating incident X-rays to a small point (spot), and deviation In order to obtain the angle and tilt angle, it is essential to process and analyze the signal detected by the two-dimensional detector, and the hurdles for putting this technology to practical use are very high.

  Further, in Patent Document 3, a tilt angle (deviation angle) of a sample single crystal is obtained by sandwiching a wedge-shaped tilt correction jig between the sample single crystal and a sample holder (sample fixing base) or rotating the sample single crystal. It is shown that the influence of the tilt angle is removed and the X-ray diffraction pattern is accurately measured. However, preparing a wedge-shaped tilt correction jig having the same angle as the deviation angle of the sample single crystal in advance is not applicable when the deviation angle of the surface to be measured is not known in advance. Also, it is not easy and complicated to rotate the sample single crystal accurately so as to eliminate the influence of the deviation angle and tilt angle, and the operation itself does not determine the deviation angle.

  The present invention has been made in view of the above problems, and even when the surface to be measured of the sample single crystal has a large tilt angle in addition to the deviation angle with respect to the crystal plane, the present invention is simple. It is an object of the present invention to provide an X-ray crystal orientation measuring apparatus and an X-ray crystal orientation measuring method capable of detecting a diffraction X-ray and measuring a crystal orientation.

In order to achieve the above object, the present invention is an apparatus for measuring the crystal orientation of a measured surface of a sample single crystal using X-rays,
X-ray irradiation means for irradiating the measurement surface of the sample single crystal with X-rays;
The optical axis of the X-ray that passes through the center of the sample single crystal and is rotatable about a rotation axis parallel to the surface to be measured and the direction of the rotation axis is incident on the surface to be measured and the optical axis are incident. A sample rotating means that is perpendicular to a plane that includes a normal to the surface to be measured;
X-ray detection means for detecting diffracted X-rays of X-rays irradiated on the measurement target surface of the sample single crystal from the X-ray irradiation means;
There is provided an X-ray crystal orientation measuring apparatus characterized by comprising movable means that enables the X-ray detection means to move in a direction perpendicular to a plane including the optical axis and normal line.

  As described above, by providing the movable means capable of moving the X-ray detection means in the direction perpendicular to the plane including the optical axis and the normal line, the measured surface of the sample single crystal has a large tilt angle with respect to the crystal plane. Even if it is held, it is possible to detect the diffracted X-rays deviated in the vertical direction by moving the X-ray detection means in the direction perpendicular to the plane. Measurements can be made.

  Furthermore, in order to achieve the above object, the present invention uses an X-ray crystal orientation measuring apparatus capable of moving the X-ray detection means in a direction perpendicular to a plane including the optical axis and the normal line. X-rays are irradiated onto the surface to be measured of the sample single crystal, diffracted X-rays of the X-rays irradiated on the surface to be measured are detected, and the crystal orientation of the surface to be measured is measured An X-ray crystal orientation measurement method is provided.

  In this way, by using the X-ray crystal orientation measuring apparatus of the present invention to detect the diffracted X-rays of X-rays irradiated on the surface to be measured, the surface to be measured of the sample single crystal is relative to the crystal plane. Of course, the crystal orientation of the surface to be measured can be measured and the deviation angle between the crystal surface and the surface to be measured can be measured even if it has the tilt angle.

  As described above, according to the present invention, it is possible to easily measure the crystal orientation of the measurement surface regardless of whether the measurement surface of the sample single crystal has a tilt angle with respect to the crystal surface. It can be carried out.

It is a sketch which shows the plane containing the X-ray crystal orientation measuring apparatus of this invention, the optical axis of incident X-rays, and the normal line of the to-be-measured surface into which this optical axis enters. It is a sketch which shows an example of the X-ray crystal orientation measuring apparatus of this invention. It is a three-view figure ((a) top view, (b) front view, (c) side view) which shows the detection of the diffraction X-ray from the cut surface with a tilt angle. It is the schematic ((a) whole figure, (b) sectional drawing) which shows an example of the movable means which can move an X-ray detection means to an up-down direction. It is a figure which shows the geometric relationship of a (551) surface and a (110) surface. It is a trihedral figure ((a) top view, (b) front view, (c) side view) which shows the crystal orientation measurement of the (551) plane of the [1/10 1/10 -1] direction. It is a trihedral figure ((a) top view, (b) front view, (c) side view) which shows the crystal orientation measurement of a (551) plane in the [-1 1 0] direction. It is a schematic diagram which shows the principle of a X-ray crystal orientation measurement. It is a schematic diagram which shows the cut surface, deviation angle, and tilt angle of a sample single crystal. It is a sketch which shows the conventional X-ray crystal orientation measuring apparatus. It is a three-view figure ((a) top view, (b) front view, (c) side view) which shows that the diffraction X-ray from the cut surface which does not have a tilt angle can be detected. It is a three-view figure ((a) top view, (b) front view, (c) side view) which shows that the diffraction X-ray from the cut surface with a tilt angle cannot be detected.

Hereinafter, the present invention will be described in more detail.
As described above, in the apparatus for measuring the crystal orientation of the measurement surface of the sample single crystal using X-rays, the measurement surface (cut surface) of the sample single crystal is larger than the deviation angle with respect to the crystal plane. There is a need for an X-ray crystal orientation measuring apparatus that can detect a diffracted X-ray and measure the crystal orientation even when it has an angle.

As a result of intensive studies to achieve the above object, the present inventors are an apparatus for measuring the crystal orientation of the measurement surface of a sample single crystal using X-rays,
X-ray irradiation means for irradiating the measurement surface of the sample single crystal with X-rays;
The optical axis of the X-ray that passes through the center of the sample single crystal and is rotatable about a rotation axis parallel to the surface to be measured and the direction of the rotation axis is incident on the surface to be measured and the optical axis are incident. A sample rotating means that is perpendicular to a plane that includes a normal to the surface to be measured;
X-ray detection means for detecting diffracted X-rays of X-rays irradiated on the measurement target surface of the sample single crystal from the X-ray irradiation means;
An X-ray crystal orientation measuring apparatus characterized by comprising a movable means that enables the X-ray detection means to move in a direction perpendicular to a plane including the optical axis and normal line. The present invention was completed.

  Hereinafter, the present invention will be described in detail as an example of an embodiment with reference to the drawings, but the present invention is not limited thereto.

First, the X-ray crystal orientation measuring apparatus of the present invention will be described with reference to FIG.
FIG. 1 is a sketch showing a plane including an X-ray crystal orientation measuring apparatus of the present invention, an optical axis of incident X-rays, and a normal line of a surface to be measured on which the optical axis is incident. The X-ray crystal orientation measuring apparatus 100 includes an X-ray irradiation unit 11, a sample rotation unit 14, an X-ray detection unit 12, and a movable unit 17. The sample single crystal 13 is placed on the sample rotating means 14 so that the X-ray is incident on the surface to be measured.

  X-rays radiated from the X-ray irradiating means 11 are incident on the surface to be measured of the sample single crystal 13 and are detected by the X-ray detecting means 12 when the Bragg reflection condition is satisfied. The sample rotating means 14 has a structure that can rotate around the rotation axis A with the sample single crystal 13 placed thereon. At this time, the rotation axis A passes through the center of the sample single crystal 13 and is parallel to the surface to be measured (the surface on the side where X-rays enter the sample single crystal). Further, the direction of the rotation axis A is perpendicular to the plane 16 including the optical axis of the X-ray incident on the surface to be measured and the normal 18 of the surface to be measured on which the optical axis is incident. The X-ray detection means 12 can be moved in a direction perpendicular to the plane 16 by the movable means 17. When the plane 16 is a horizontal plane, the movable unit 17 moves the X-ray detection unit 12 in the vertical (vertical) direction.

  In the sample single crystal having a tilt angle between the measured surface of the sample single crystal and the crystal plane, the diffracted X-rays are shifted to the upper side (or the lower side) of the X-ray detection unit. When it is within 16, it does not enter the X-ray detection means. Therefore, in the X-ray crystal orientation measuring apparatus 100 of the present invention, the X-ray detection means is configured to be movable in the vertical direction from the plane 16 (that is, the XZ plane in the figure) as shown in FIG. That is, as illustrated in the plan view of the X-ray crystal orientation measuring apparatus of the present invention in FIG. 2 and the three views of the method for detecting diffracted X-rays from the cut surface having the tilt angle in FIG. By moving the line detection means 12 from the original position in parallel in the Y-axis direction (vertical direction), the crystal orientation can be measured even for sample single crystals having various tilt angles.

FIG. 2 is a sketch showing an example of the X-ray crystal orientation measuring apparatus of the present invention. The plane 16 is removed from FIG. 1 to show the overall configuration of the apparatus in an easy-to-understand manner.
FIG. 3 is a three-view diagram ((a) top view, (b) front view, (c) side view) showing detection of diffracted X-rays from a cut surface having a tilt angle. The sample single crystal shown in FIG. 3 has a deviation angle φ and a tilt angle ψ between the cut surface (surface to be measured) and the just crystal surface. When X-rays are incident on the sample single crystal 13 from the direction shown in FIG. 3, the diffracted X-rays deviate upward as shown in FIGS. 3B and 3C. Therefore, the X-ray detection means 12 is moved upward by the movable means 17 and measurement is performed at a height (position) at which diffracted X-rays are detected. Thus, by using the X-ray crystal orientation measuring apparatus of the present invention, the crystal orientation of the measurement surface can be measured even when the measurement surface of the sample single crystal has a tilt angle.

For example, a rack and pinion (gear) mechanism as shown in FIG. 4 can be considered as the movable means that enables the X-ray detection means to move in the vertical direction. 4A is an overall schematic view of the movable means 17, and FIG. 4B is a cross-sectional view on a horizontal plane including the pinion. The movable means 17 is composed of a rack 21 that is cut into a rod, a pinion 22 that is a gear, an X-ray detection means support (inner pillar) 23, an X-ray detection means support (outer cylinder) 24, and a knob 25. The rack 21 may be formed by directly processing the X-ray detection means column (inner column) 23. The X-ray detection means support column (inner column) 23 is provided with a concave portion, and the X-ray detection means support column (outer cylinder) 24 is provided with a convex portion in the vertical direction, and an inner column detent portion 26 is formed. By rotating the knob 25, the pinion 22 rotates and the X-ray detection means support (inner column) 23 moves up and down through the rack 21. Thereby, the X-ray detection means can be moved in the vertical direction.
Here, the mechanism of the rack and pinion is exemplified as the movable means, but the mechanism is not limited to this as long as the mechanism can translate the X-ray detector in the vertical direction. As another example, a moving mechanism using a pulse motor may be used.

Next, the X-ray crystal orientation measuring method of the present invention will be described with reference to FIGS.
First, in the X-ray crystal orientation measuring apparatus 100 of the present invention illustrated in FIG. 2, the sample rotating means 14 so that X-rays radiated from the X-ray irradiating means 11 are incident on the measurement target surface of the sample single crystal 13. Placed on. Here, the sample single crystal 13 in FIG. 2 is a wafer, but it is not necessarily in the shape of a wafer, and may be in the shape of a cylinder or a rectangular parallelepiped. Next, the sample single crystal 13 is rotated about the rotation axis A, and the X-ray detection means 12 detects the diffracted X-rays at a position that satisfies the Bragg diffraction condition.

  At this time, as shown in FIG. 3C, when there is a tilt angle ψ between the measured surface of the sample single crystal and the just crystal plane, the diffracted X-ray is incident on the optical axis of the incident X-ray and the optical axis. It proceeds in a direction deviating upward from a plane including the normal line of the surface to be measured (in FIG. 3, a horizontal plane including the optical axis of the incident X-ray). For this reason, the movable means 17 moves the X-ray detection means 12 upward in parallel to detect diffracted X-rays. Thereby, even if there is a tilt angle between the measured surface of the sample single crystal and the just crystal surface, the crystal orientation of the measured surface can be measured. That is, even if there is a tilt angle between the cut surface of the wafer cut from the ingot and the just crystal surface, the deviation angle between the cut surface and the just crystal surface can be measured, and the adjustment and management of the cutting angle can be performed. It can be carried out.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited to these.

  The distance (d) between the (551) planes of the (551) single crystal of silicon is 0.076 nm, and the characteristic X-ray wavelength λ = 0.154 nm of a Cu target usually used in an X-ray crystal orientation measuring apparatus (goniometer). The diffraction X-ray cannot be obtained because it is smaller than ½ of. On the other hand, the diffracted X-rays from the (110) just crystal plane that is 8 ° 03 ′ (8 ° 03 minutes) away from the (551) plane in the [0 0 −1] direction are X It can be measured with a linear crystal orientation measuring device.

FIG. 5 shows the geometric relationship between the (551) plane and the (110) plane. In FIG. 5, when X-rays are incident in the [1/10 1/10 -1] direction, as shown in FIG. 6, (551) diffracted X-rays from the silicon single crystal 31 move the X-ray detection means up and down. It can be detected without moving to. As shown in FIG. 6A, (8 ° 03 ′ + deviation angle φ) corresponds to the deviation angle described so far, but there is no angle corresponding to the tilt angle as shown in FIG. 6C. (Ie, 0 °). At this time, the difference between the actually measured crystal orientation and the aforementioned angle 8 ° 03 ′ is the deviation angle of the (551) crystal in the [1/10 1/10 −1] direction.
In the Miller index, a negative number is originally written with a bar on top, but in this specification, it is shown as a negative number for convenience.

  A (551) single crystal of silicon is placed on the sample rotating means of the X-ray crystal orientation measuring apparatus of the present invention, and X-rays [1] are applied to the cut surface so as to obtain diffracted X-rays from the (110) plane. / 10 1/10 −1] direction, and the angle formed by the cut surface and the (110) plane was measured. The measured angle was 8 ° 30 ′, and the deviation angle in the [1/10 1/10 −1] direction of this (551) crystal was 27 ′.

  Next, when the X-ray is incident on the same silicon (551) single crystal in the [-1 1 0] direction orthogonal to the [1/10 1/10 -1] direction shown in FIG. Thus, the diffracted X-rays cannot be detected by the X-ray detection means. As shown in FIGS. 7B and 7C, the X-ray incident on the (110) plane has an angle of 8 ° 03 ′ corresponding to the tilt angle between the cut plane and the (110) plane. This is due to the fact that the X-ray detection means moves upward (or downward).

  Therefore, when the X-ray detection means is moved 60 mm upward from the original position by the movable means illustrated in FIG. 4, the diffracted X-rays enter the X-ray detection means, and [1/10 1/10 -1] direction, the X-ray diffracted from the X-ray incident in the [-1 1 0] direction perpendicular to the direction can also be measured accurately, and the deviation angle of the (551) crystal in the [-1 1 0] direction can be easily and easily determined. I was able to ask.

  As described above, according to the X-ray crystal orientation measuring apparatus and the X-ray crystal orientation measuring method of the present invention, the target electrode of the X-ray crystal orientation measuring apparatus is replaced to change the wavelength of the characteristic X-ray (Bragg Without changing the reflection condition of the crystal, the crystal orientation of the crystal having a large tilt angle can be obtained by providing the X-ray crystal orientation measuring device with a minimum mechanism for adjusting the height of the X-ray detection means. Can be measured accurately.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

11 ... X-ray irradiation means, 12 ... X-ray detection means, 13 ... Sample single crystal,
14 ... Sample rotating means, 15 ... Notch,
16: a plane including the optical axis of incident X-rays and the normal of the surface to be measured on which the optical axis is incident,
17 ... movable means, 18 ... normal, 21 ... rack, 22 ... pinion,
23 ... X-ray detection means support (inner pillar), 24 ... X-ray detection means support (outer cylinder),
25 ... Knob, 26 ... Detent of inner pillar, 31 ... (551) Silicon single crystal,
100: X-ray crystal orientation measuring apparatus.

Claims (2)

An apparatus for measuring the crystal orientation of a measured surface of a sample single crystal using X-rays,
X-ray irradiation means for irradiating the measurement surface of the sample single crystal with X-rays;
The optical axis of the X-ray that passes through the center of the sample single crystal and is rotatable about a rotation axis parallel to the surface to be measured and the direction of the rotation axis is incident on the surface to be measured and the optical axis are incident. A sample rotating means that is perpendicular to a plane that includes a normal to the surface to be measured;
X-ray detection means for detecting diffracted X-rays of X-rays irradiated on the measurement target surface of the sample single crystal from the X-ray irradiation means;
An X-ray crystal orientation measuring apparatus characterized by comprising a moving means that allows the X-ray detection means to move in a direction perpendicular to a plane including the optical axis and normal line. The X-ray crystal orientation measuring apparatus according to claim 1, wherein the X-ray crystal orientation measuring device is capable of moving the X-ray detection means in a direction perpendicular to a plane including the optical axis and the normal line. An X-ray crystal orientation measuring method comprising: irradiating X-rays, detecting X-ray diffraction X-rays irradiated on the surface to be measured, and measuring the crystal orientation of the surface to be measured.

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