JP2013217825A - X-ray crystal azimuth measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly and efficiently achieve azimuth measurement related to a single crystal material.SOLUTION: It is assumed that rough azimuths of main lattice planes such as (100), (110) and (111) in a single crystal material to be a measurement object are recognized beforehand, and the azimuth of an azimuth mark of an orientation flat, a notch or the like is roughly recognized. Then, for two or more planes for which exponents are recognized, by calculating a diffraction vector utilizing energy analysis by EDXRD using a semiconductor X-ray detector 10, all three axial azimuths are determined on the basis of the calculation result. Also, as needed, a main surface azimuth of a cut surface and a formation azimuth of the azimuth mark are calculated.

Description

  The present invention relates to a measurement method for measuring the crystal orientation of a single crystal.

  In general, a single crystal is a substance in which atoms or molecules are regularly and periodically arranged. Therefore, in a single crystal, the crystal orientation is the same everywhere in the crystal. For example, Si (silicon) crystal used as a semiconductor substrate and sapphire crystal used as a substrate of a light emitting diode are known as single crystals in the industry.

  A single crystal is generally produced in the form of a large ingot, and when used as a product, the ingot is cut into, for example, a thin wafer-shaped wafer (Wafer). Then, various processes such as a film forming process, masking, etching, wiring process, and dicing are performed on the wafer.

  Single crystals usually have different mechanical, electrical, magnetic, optical, and thermal properties depending on the direction. Therefore, in order to effectively use the properties of crystals to obtain a desired product, it is necessary to examine the orientation of the crystal ingot and cut the crystal ingot in a predetermined direction with respect to that orientation to produce a wafer.

  In addition, it is necessary to attach a mark indicating the reference of the orientation (hereinafter referred to as an orientation mark) to the cut wafer so that various processes such as a film forming process can be accurately performed with respect to the crystal orientation. There is. This orientation mark is conventionally known as an orientation flat surface (orientation flat surface) that is a flat surface formed by cutting, polishing, or the like, or a notch that is a V-shaped groove formed by a cutting tool or the like. It has been.

  Furthermore, inspection whether the orientation of the created wafer is within an allowable angle range with respect to the cut surface, inspection whether an orientation mark such as a notch is formed at a desired position with respect to the crystal orientation, etc. Need to do.

  Conventionally, as a method for forming an orientation mark in a predetermined crystal orientation of a single crystal ingot and further cutting out the single crystal ingot along a predetermined crystal orientation, a method shown in the process diagram of FIG. 1 is known. In this conventional method, first, a both-ends cutting process is performed in process P101. Specifically, the conical portions at both ends of the raw single crystal ingot 101 shown in FIG. 2 are cut to form a cylindrical single crystal ingot 102. The outer peripheral surface of the single crystal ingot 102 is in a state having irregular irregularities as it is at the time of crystal growth.

Next, in step P102, the outer peripheral surface of the single crystal ingot 102 is ground using a cylindrical grinder to form a single crystal ingot 103 that has been subjected to outer peripheral processing. Next, in step P103, a position where an orientation mark, for example, a notch is to be processed is detected using the first crystal orientation measuring apparatus. For example, the first crystal orientation measuring apparatus irradiates the outer peripheral surface of the single crystal ingot 103 with X-rays and rotates the ingot 103 around its own central axis to detect the orientation in which the notch is to be processed. .

  The first crystal orientation measuring apparatus performs measurement based on diffracted X-rays obtained when a sample is irradiated with characteristic X-rays. For example, it is disclosed in Patent Document 1, Patent Document 2, and Patent Document 3. ing.

Next, notch processing is performed in step P104. Specifically, a notch which is a groove having a V-shaped cross section is formed on the outer peripheral surface of the ingot 103 at a position detected as a position where the notch is to be machined using a cutting tool having a triangular cross section. As shown by the reference numeral 104 in FIG. By this notch 104, the crystal orientation in the single crystal ingot 105 can be recognized, and various processes for the subsequent ingot 105 can be accurately performed on a desired crystal lattice plane.

Next, in step P105, carbon as an intermediate material is attached to a predetermined position of the ingot 105 to form a plate, and a reference metal fitting is attached to the plate. Next, in step P106, the surface orientation of one end face of the ingot 105 is measured by the second crystal orientation measuring device with the reference metal fitting of the ingot 105 as a reference.

The second crystal orientation measuring apparatus performs measurement based on diffracted X-rays obtained when a sample is irradiated with characteristic X-rays from four directions or two directions, and is disclosed in Patent Document 4, for example.
In addition, for example, Patent Document 5 shows the basis for measuring in four directions or two directions in detail.

  Next, a wafering process is performed in process P107. Specifically, the orientation of the reference metal fitting of the ingot 105 is corrected based on the measured plane orientation, and a plurality of wafers 106 are removed from the ingot 105 in one step by a multi-wire saw provided in the wafer ring apparatus. cut.

  Next, in step P108, the wafer surface orientation and the notch orientation are inspected by the third crystal orientation measuring device. The third crystal orientation measuring apparatus is performed, for example, by irradiating the wafer surface with X-rays in a state where the wafer is positioned by a positioning member having a V-shaped cross section fitted to the notch.

  The third crystal orientation measuring apparatus performs measurement based on diffracted X-rays obtained when a sample is irradiated with characteristic X-rays from four or two directions, and is disclosed in, for example, Patent Document 5. . Further, although not based on X-ray irradiation from multiple directions, Patent Document 6 discloses a method for obtaining a deviation angle δ between a cut surface and a lattice plane by X-ray diffraction. An apparatus for measuring the notch orientation is disclosed in Patent Document 7, for example.

In the above-described conventional crystal orientation measuring apparatus, each of the first, second and third crystal orientation measuring apparatuses performs measurement based on diffracted X-rays obtained when the sample is irradiated with characteristic X-rays.
The first crystal orientation measuring device is a dedicated machine for detecting the notch orientation, and the second crystal orientation measuring device is a dedicated machine for detecting the orientation of the ingot cut surface. Furthermore, the third crystal orientation measuring apparatus individually measures the main surface orientation and the notch orientation of the wafer.

  As described above, the conventional azimuth measuring apparatus using characteristic X-rays individually measures the plane azimuth and the notch azimuth. Therefore, there is a problem that it takes a long time for the measurement. Further, since X-rays must be irradiated to the sample from four directions or two directions at the time of measurement, the X-ray optical system must be rotated or linearly moved. Therefore, the applied crystal orientation measuring apparatus has a structure. There was a complicated problem.

  In recent years, single crystal ingots have become large, and the diameter has become as large as 300 mm. In the future, it is predicted that a larger single crystal ingot having a diameter of 450 mm will be put to practical use. In the measuring apparatus disclosed in Patent Document 4, a large single crystal ingot is hindered by moving the X-ray optical system relative to the single crystal ingot while the single crystal ingot is held in a fixed position by a reference fitting. It can be measured without any problems.

  By the way, conventionally, a crystal orientation measuring apparatus using the Laue method is known. For example, Patent Documents 8 and 9 disclose such devices. In the Laue method, a sample is generally irradiated with continuous X-rays focused on a small-diameter parallel beam by a collimator, and diffraction lines generated at different angles according to the difference in wavelength are detected as Laue spots by a two-dimensional X-ray detector. Is the method.

Patent Document 8 and Patent Document 9 mainly measure the crystal orientation of a substance having a sub-grain structure or a lineage structure, rather than measuring the orientation of a single crystal substance (that is, a substance having a single domain structure). It is an object. The subgrain structure is a crystal composed of many crystal grains, which is difficult to obtain a single domain structure crystal, such as a meteorite crystal (CaF ₂ ; Fluorite), a magnesia (MgO) crystal, This subgrain structure is included in ferrite crystals and the like.

In addition, the lineage structure is a kind of defect structure. Therefore, the lineage structure may show a behavior in which the crystal orientation continuously changes depending on the location. For example, this lineage structure is included in oxide crystals such as sapphire, LN (lithium niobate; LiNbO ₂ ), LT (lithium tantalate; LiTaO ₂ ), and the like.

  Patent Document 8 discloses a technique for detecting a center spot of Laue spots by setting the camera length to be relatively long, such as 100 to 300 mm, and calculating a lattice plane normal from the center spot. In Patent Document 9, all three-axis orientation measurement is performed by setting the camera length to be relatively short, such as about 35 mm (that is, measurement for examining the direction in which the crystal axis is formed with respect to the outer shape of the crystal). ) And setting a long camera length to measure the plane orientation (that is, measurement for examining the normal direction of a specific lattice plane).

  Patent Document 8 and Patent Document 9 disclose that the Laue method is used to perform all three-axis orientation measurement and plane orientation measurement of a single crystal, but an orientation mark such as a notch is attached to the single crystal material. Is not mentioned at all in these publications.

The inventions disclosed in Patent Document 8 and Patent Document 9 have been previously proposed by the inventor (the inventor) according to the present application.
Furthermore, the present inventor has made it possible to quickly and efficiently measure the orientation of both the crystal orientation and the orientation in which orientation marks such as notches are formed with respect to the single crystal material using a crystal orientation measuring device having a simple configuration based on the Laue method. Based on the idea that it can be realized in an effort, the inventors have made extensive studies and have already proposed an invention of an X-ray crystal orientation measuring apparatus and an X-ray crystal orientation measuring method (Japanese Patent Application No. 2010-220088).

JP-A-3-255951, (pages 2 and 3, FIG. 1) JP-A-3-255948, (pages 3 to 4, FIGS. 2 to 4) Japanese Patent Laid-Open No. 11-014560 (pages 1 to 5, FIG. 1) JP-A-9-033456 (page 4, FIG. 3) Japanese Patent Application Laid-Open No. 57-136151 (pages 4-5, FIG. 4) JP-A-57-136150 (pages 2-5, FIG. 3) Japanese Patent Laid-Open No. 6-167463 (pages 3 to 4, FIGS. 2 and 3) Japanese Patent Laying-Open No. 2005-121372 (pages 5-9, FIG. 1) JP-A-2005-241578 (pages 5 to 12, FIGS. 2 and 4) DE19907453A1

INTERNATIONL TABLES FOR X-RAY CRYSTALLOGRAPHY / VOL.IV Section3 / WALTER C. HAMILTON / Section 3.4.2 Determination of U from two reflections

  The present invention has been made in view of the above findings by the present inventor, and is a new technique different from the previously proposed inventions of Patent Document 8 and Patent Document 9 and the invention according to Japanese Patent Application No. 2010-220088. The purpose is to quickly and efficiently realize orientation measurement for single crystal materials.

The present invention is premised on crystal orientation measurement using the Laue method, as in the inventions disclosed in Patent Documents 8 and 9, and the invention according to Japanese Patent Application No. 2010-220088.
[Principle of conventional orientation measurement method using Laue method]
FIG. 3 shows a principle diagram of the plane orientation measuring method disclosed in Patent Document 8 and Patent Document 9. In this principle diagram, the xy plane of the (x, y, z) orthogonal coordinate system matches the sample surface. In the surface orientation measuring methods disclosed in Patent Document 8 and Patent Document 9, the incident X-ray is in the yz plane, is incident on the sample surface at an angle ω, and is irradiated to the origin. X-rays are diffracted by a grating plane substantially parallel to the sample surface.

  A Laue image, which is a diffraction image, is captured by a light receiving surface of a two-dimensional X-ray detector, for example, a CCD (Charge Coupled Device) camera, which is also on the yz plane and arranged in the X-ray emission direction at an angle ω. The diffraction line vector k is obtained from the position of the diffraction image on the CCD light receiving surface, and the lattice plane normal vector V can be calculated by the simple vector calculation shown in FIG.

  The plane orientation can be expressed by components Vx, Vy, Vz and the azimuth angle α and azimuth angle β shown in FIG. 4 after the lattice plane normal vector V is converted into a unit vector. The azimuth angle α is an angle formed by the sample surface normal (z axis) and the lattice surface normal. The azimuth angle α is the maximum inclination angle of the lattice plane. The azimuth angle β is an angle formed by the projection line of the lattice plane normal line onto the xy plane (sample surface) and the x axis. The azimuth angle β is the direction of inclination of the lattice plane. Instead of expressing the plane orientation by azimuth angles α and β, it is also possible to decompose and output the tilt angles δxz and δyz in two directions of the x-axis and y-axis orthogonal to each other.

[Outline of X-ray crystal orientation measurement method according to the present invention]
The X-ray crystal orientation measuring method according to the present invention also has the basic principle that the plane orientation is expressed by the components Vx, Vy, Vz, the azimuth angle α, and the azimuth angle β after converting the lattice plane normal vector V into a unit vector. The surface orientation measurement method disclosed in Patent Document 8 and Patent Document 9 is the same.

In the X-ray crystal orientation measuring method according to the present invention, X-rays are incident perpendicularly to the sample surface.
Then, diffracted X-rays diffracted from the grating surface are detected based on the principle of EDXRD (Energy Dispersive XRD) using a semiconductor X-ray detector such as an SDD (silicon drift detector). The method is adopted.

In the present invention, the approximate orientation of major lattice planes such as (100), (110), (111) in the single crystal material to be measured is known in advance, and orientation marks such as orientation flats and notches are attached. It is assumed that the general direction should be known.
Then, for two or more surfaces with known indices, the inclination is obtained by using energy analysis by EDXRD using a semiconductor X-ray detector, a diffraction vector is calculated from the inclination, and all three axes are calculated based on the calculation result. Determine the bearing. Moreover, the main surface orientation of a cut surface and the formation orientation of an orientation mark are calculated as needed.

Ｘ線波長λとエネルギＥの関係は次のとおりであり、これにＢｒａｇｇの式を適用すると、

の関係を得る。
ここで、ｈはプランク定数、ｃは光速度である。
格子面１の面間隔ｄはÅ単位、エネルギＥはｋｅＶ単位での計算となる。これが、ＥＤＸＲＤの基本式である。 [Basic principle of crystal orientation measurement by EDXRD]
Next, the basic principle of crystal orientation by EDXRD adopted by the present invention will be described.
FIG. 5 shows the basic principle of crystal orientation measurement using EDXRD. When continuous X-rays (continuous wavelength X-rays) parallelized and directed by a collimator or the like are incident at an incident angle θ on the grating surface 1 having a surface interval d, the wavelength given by the Bragg equation shown in (1) λ is selected, producing diffracted X-rays.

The relationship between the X-ray wavelength λ and the energy E is as follows, and applying the Bragg equation to this,

Get a relationship.
Here, h is Planck's constant and c is the speed of light.
The spacing d of the lattice plane 1 is calculated in units of Å, and the energy E is calculated in units of keV. This is the basic formula of EDXRD.

A calculation example using this basic formula is shown below.
If Si (004), d = 1.35763 mm, and θ = 20 °, E = 13.352 keV.
When the inclination of the lattice plane changes by Δθ as indicated by reference numeral 1a, the reflection direction of the diffracted X-rays changes and the energy E changes accordingly. For example, when the inclination of the lattice plane 1 changes by Δθ = −0.1 ° and θ = 19.9 °, the energy changes to E = 13.417 keV. The amount of change is ΔE = + 65.

  Furthermore, in order to capture this 1/5 angle change Δθ = 0.02 °, the performance of an X-ray detector capable of capturing ΔE = 13 eV by the amount of energy change is required. If the performance of the SDD commercially available in recent years is taken, this energy change can be sufficiently captured.

又は、

The amount of change in energy can also be calculated by differentiating equation (2) according to the following equation (3) or (4).

Or

  In addition, the direction of the diffraction line changes by twice the inclination of the grating surface 1. Therefore, the measurable Δθ range is determined by the sensitive area on the sensitive surface (detection surface) of the X-ray detector.

[Configuration of the present invention]
The X-ray crystal orientation measuring method according to the present invention includes the following procedures (a) to (e).
(A) irradiate X-rays perpendicular to the sample surface of a single crystal sample in which the approximate orientation of the main lattice plane and the approximate direction to which the orientation mark should be attached are known;
Two or more lattice planes with known indices other than the main lattice plane in the single crystal sample are used as measurement target lattice planes.
Set the reference position in the theoretical direction that the diffracted X-rays will be reflected from the measurement target lattice plane,
The semiconductor X-ray detector is disposed at the reference position, and the energy of the diffracted X-ray reflected from the measurement target lattice plane is detected by the semiconductor X-ray detector.
(B) Based on the energy of the diffracted X-ray detected by the semiconductor X-ray detector, the Bragg angle of the diffracted X-ray reflected from the measurement target lattice plane is obtained, and the sample surface of the single crystal sample including the diffracted X-ray trajectory The inclination angle α of the measurement target lattice plane in the plane perpendicular to is calculated from the obtained Bragg angle.
(C) A partial area of the sensitive surface of the semiconductor X-ray detector disposed at the reference position is covered with a shielding plate, and the shielding plate, the sample, and the semiconductor X-ray detector are rotated within the sample surface of the single crystal sample. The tilt angle φ in the in-sample rotation direction of the measurement target lattice plane is calculated based on a change in the intensity of the diffracted X-ray detected by the semiconductor X-ray detector at that time.
(D) A diffraction vector for the measurement target lattice plane is calculated based on the obtained inclination angles α and φ.
(E) An orientation of an arbitrary lattice plane in a single crystal sample is obtained based on diffraction vectors calculated for two or more measurement target lattice planes.

As described above, the single crystal sample to be measured by the X-ray crystal orientation measurement method according to the present invention has the approximate orientation of the main lattice plane and the approximate direction to which the orientation mark should be attached previously known. It is necessary. Here, the “approximate direction, approximate orientation” means the orientation of the semiconductor X-ray detector to such an extent that the diffracted X-ray reflected from the measurement target lattice plane can be incident on the sensitive surface in advance. Or the direction must be known.
These known “approximate orientations of major grid planes and approximate directions to which orientation marks should be attached” are determined from the exact orientations of the major grid planes and the precise directions to which the orientation marks are attached. It is the X-ray crystal orientation measuring method according to the present invention that detects the deviation on the premise of the deviation.

[Differences from the invention disclosed in Patent Document 10]
In the German patent application of Patent Document 10, a single crystal sample is irradiated with X-rays, and the energy of the diffracted X-ray reflected from the lattice surface of the single crystal sample is detected, thereby determining the orientation of the lattice surface of the same material. A method of determining is disclosed.
The main differences between the invention disclosed in Patent Document 10 and the invention (present invention) according to the present application are as follows.
First, the incident angle of the X-ray with respect to the sample surface of the single crystal sample is set to be vertical in the present invention, whereas in the invention of Patent Document 10, it is incident from an oblique direction.
In the present invention, the inclination angle α is obtained based on the energy of the diffracted X-ray, and the inclination angle φ is obtained by measuring the reflection angle position of the diffracted X-ray using a shielding plate. Is calculated to obtain the orientation of an arbitrary lattice plane in the single crystal sample.
With this technique, the present invention can determine the plane orientation of a single crystal sample and the orientations of all three axes of the orientations to which the orientation mark should be attached by a series of techniques.
On the other hand, in the invention disclosed in Patent Document 10, only the energy of diffracted X-rays is used, and scanning is not performed only by fixing the X-ray detector. For this reason, it seems that the measurement is simplified at first glance, but only the plane orientation of the single crystal sample can be obtained, and another measurement operation is required to obtain the orientation to which the orientation mark should be attached. Therefore, when measuring the orientation of all three axes, the present invention is quicker and more efficient.

  ADVANTAGE OF THE INVENTION According to this invention, the orientation measurement regarding a single crystal substance can be implement | achieved rapidly and efficiently.

It is process drawing which shows the processing method of the conventional single crystal ingot. It is a figure which shows the manufacturing process of the single crystal ingot corresponding to the process drawing of FIG. It is a figure which shows the principle of the surface orientation measurement using the Laue method. It is a figure which shows the definition of azimuth angle (alpha) and (beta). It is a figure which shows the basic principle of the crystal orientation measurement using EDXRD. It is process drawing which shows the general processing method of Si single crystal ingot used as the measuring object of the X-ray crystal orientation measuring method which concerns on embodiment of this invention. It is a figure which shows the manufacturing process of the single crystal ingot corresponding to the process drawing of FIG. It is a schematic diagram which shows the outline | summary of the apparatus structure for enforcing the X-ray crystal orientation measuring method which concerns on embodiment of this invention. It is a figure for demonstrating attachment of the sample to the measuring apparatus in embodiment of this invention, and utilization of 115 reflection. It is a figure for demonstrating determination of the diffraction line direction by the half shutter in embodiment of this invention. It is a figure for demonstrating the setting of ROI performed at the time of determination of the diffraction line direction by the half shutter in embodiment of this invention. It is a figure for demonstrating calculation of the diffraction vector in embodiment of this invention. It is a figure for demonstrating the determination of the orientation matrix U in embodiment of this invention. It is a figure for demonstrating calculation of an angle required for the crystal orientation inspection and correction process in embodiment of this invention. It is a figure for demonstrating the parallel processing by mounting two X-ray detectors in other embodiment of this invention. It is a figure for demonstrating the determination of the diffraction line direction by the half shutter in other embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In the present embodiment, a method of simultaneously measuring both the plane orientation and the orientation in which an orientation mark such as a notch is formed, using a Si single crystal ingot or a wafer cut out from the ingot as a measurement object will be described. However, the measurement object of the present invention is not limited to this, and it is needless to say that it can be applied to the measurement of various single crystal orientations.

[Processing method of single crystal ingot]
First, with reference to FIG.6 and FIG.7, the general manufacturing process of the Si single crystal ingot used as the measuring object of the X-ray crystal orientation measuring method which concerns on this embodiment is demonstrated.
It is assumed that a wafer having a Si single crystal ingot with a rod axis of <001>, a plane orientation of (100) and a notch (110) is manufactured.

  In step P1, a both-end cutting step is performed. Specifically, the conical portions at both ends of the raw single crystal ingot 211 shown in FIG. 7 are cut to form a cylindrical single crystal ingot 212. The Si single crystal ingot 211 has four crystal habit lines 203 on the outer peripheral surface corresponding to (110). The outer peripheral surface of the single crystal ingot 212 is in a state having irregular irregularities as it is during crystal growth.

  Next, in step P2, a marking line 204 as a mark is attached to the end face position of the ingot 212 corresponding to the crystal habit line 203. In step P3, the outer peripheral surface of the single crystal ingot 212 is ground using a cylindrical grinder to form a single crystal ingot 213 that has been subjected to outer peripheral processing.

  Subsequently, in step P4, both the surface orientation and notch orientation of the ingot 213 are obtained simultaneously. In this process P4, the X-ray crystal orientation measuring method according to this embodiment described later can be used.

  Next, based on the obtained plane orientation and notch orientation, in step P5, a notch 214 is formed in the outer periphery (110) of the ground ingot 213 by machining. Then, a plurality of wafers 216 are cut out from the ingot 215 by a multi-wire saw provided in the wafer ring apparatus in one step.

  Thereafter, in step P6, the wafer surface 216 and the notch direction are inspected for the cut wafer 216. The X-ray crystal orientation measuring method according to this embodiment, which will be described later, can also be used for this inspection.

[Apparatus configuration for carrying out the measurement method according to this embodiment]
FIG. 8 is a schematic diagram showing an outline of an apparatus configuration for carrying out the X-ray crystal orientation measuring method according to the present embodiment.
In the apparatus, orthogonal coordinates (x, y, z) are set in advance. As will be described later, a sample surface 10a of the Si single crystal sample 10 to be measured is arranged on the xy plane. That is, the sample surface normal is positioned according to the z axis.
X-rays are emitted from the X-ray source 11, collimated by the collimator 12, and then enter the sample surface 10 a of the sample 10 perpendicularly from the z-axis direction.
The sample 10 can perform in-plane rotation (φ rotation). In-plane rotation is rotation around the z-axis. Note that the sample 10 may be fixed and the equator plane (yz plane) including the X-ray detector 13 may be rotated around the z axis.

  The X-ray detector 13 can be rotated around the x-axis (2θ rotation) in the equator plane. By this 2θ rotation, the sensitive surface (X-ray detection surface) of the X-ray detector 13 can be positioned in the direction in which the diffracted X-rays are reflected from the target grating surface. The angle 2θ is an angle formed by the reflection direction of the diffracted X-rays with respect to the incident direction of the X-rays to the sample 10. In this embodiment, X-rays are incident in the z-axis direction, and thus diffracted along the xy plane. When X-rays are reflected, 2θ = 90 °. The angle of 2θ is set in a range of 110 to 160 ° in which the X-ray detector 13 does not interfere with the sample 10 and the collimator 12.

  The present invention employs a semiconductor X-ray detector with high energy resolution in order to detect the energy of diffracted X-rays reflected from the lattice plane of the sample 10. In the present embodiment, an SDD (silicon drift detector) that is particularly small and does not require liquid nitrogen as a cooling medium is employed as the X-ray detector 13.

  On the front surface of the X-ray detector 13, a half shutter 14 (shielding plate) for shielding X-rays is disposed so as to be freely opened and closed. The half shutter 14 does not shield the sensitive surface of the X-ray detector 13 when opened. On the other hand, when the half shutter is in the closed state, the end face coincides with the equator plane and is set so as to cover half of the sensitive surface of the X-ray detector.

[Specific example of X-ray crystal orientation measurement method]
Next, an orientation measurement method using a Si single crystal with a plane orientation (001) as a measurement object will be described.
In this embodiment, the crystal orientation is measured by paying attention to diffracted X-rays reflected from two (115) lattice planes. However, as long as the diffraction X-rays can be detected by the X-ray detector, it is possible to focus on the diffraction X-rays from other than (115) lattice plane. However, as a diffracted X-ray that avoids interference between the X-ray detector and surrounding components and has a sufficiently large energy, the (115) diffracted X-ray reflected from the grating plane is preferable.

<1. Attaching the sample to the measuring device and using 115 reflection>
First, as shown in FIGS. 9A and 9B, orthogonal coordinates (X, Y, Z) representing the sample 10 are determined on the sample surface 10a. That is, the z axis is aligned with the normal direction of the sample surface. In the case of a wafer, the direction in which the orientation mark 10b such as a notch or orientation flat is formed is taken as the y-axis (FIG. 9A). Further, in the case of an ingot-shaped sample, the planned formation direction 10c of the orientation mark that can be known from the crystal habit line before cylindrical grinding is taken as the y-axis (FIG. 9B).
Thus, by defining the orthogonal coordinates (X, Y, Z) representing the sample 10, the orthogonal coordinates (X, Y, Z) and the crystal axes on the lattice plane (115) of the sample shown in FIG. Regarding the relationship with the coordinates (a, b, c), the z-axis and the c-axis are substantially the same, and the a-axis, the b-axis, the x-axis, and the y-axis are rotated by approximately 45 °.
Note that the crystal axis coordinates (a, b, c) of the sample shown in FIG. 9C are [100] for the a axis, [010] for the b axis, and [001] for the c axis.

In this embodiment, the lattice plane of the sample aimed to be used for diffraction is (115). V ₁₁₅ is the lattice plane normal vector. X-ray diffraction by the grating surface (115) is called "115 reflection".
The lattice plane normal vector V ₁₁₅ is inclined 15.79 ° with respect to the c-axis [001].
The lattice plane equivalent to (115) is arranged in four-fold rotational symmetry around the c-axis or z-axis. The inclination direction of the lattice plane normal vector is almost in the x-axis and y-axis directions. The arrangement of each axis is as shown in the simplified stereo projection diagram shown in FIG.

  The sample 10 is placed on the reference plane of the measuring apparatus shown in FIG. 8 (the xy plane of orthogonal coordinates set in the measuring apparatus), and the X and Y axes of the sample coordinates are parallel to the x and y axes of the apparatus coordinates. By setting to, 115 reflection can be captured by the X-ray detector 13. X-rays from the X-ray source 11 are irradiated perpendicularly to the sample surface 10 a of the sample 10 through the collimator 12.

As shown in Table 1, the 115 reflection in the Si single crystal has a Bragg angle θ calculated in an ideal orientation of 74.20 ° when perpendicularly incident on the crystal surface (sample surface), and an X-ray detector is disposed. The 2θ angle is 148.41 °, and the energy of X-rays selected by diffraction is 6.05 keV.

なお、（２）式における数値１２．４は、より正確には１２．３９８４３であり、上記（５）式にはこの数値を代入してある。 <2. Energy analysis by X-ray detector (SDD)>
Therefore, the 2θ angle at which the X-ray detector 13 is disposed is set to 148.41 °, and the sample measurement is started.
First, the half shutter 14 is opened, X-rays are irradiated perpendicularly to the sample surface 10a of the sample 10, and 115 reflected diffraction lines are counted for a predetermined time by the X-ray detector (SDD) 13. The spectrum of the diffracted X-ray detected in this way is analyzed to determine the peak center energy E. The Bragg angle θ corresponding to the energy E can be obtained from the following equation obtained by converting the equation (2).

The numerical value 12.4 in the expression (2) is more precisely 12.39843, and this numerical value is substituted into the above expression (5).

<3. Calculation of lattice plane inclination>
From the measured energy value E, the Bragg angle θ of the sample can be obtained using equation (5). The Bragg angle (theoretical value) when there is no inclination between the Z axis and the lattice plane (115) is θ = 74.207 ° as shown in Table 1. Therefore, the difference Δθ _Y between the Bragg angle θ (measured value) obtained from the measured energy value E and the black angle (theoretical value) can be calculated as follows.
Δθ _Y = θ-74.207 °
This value is a change in the inclination of the lattice plane (115) in the Y-axis direction.

The tilt angle of the diffracted X-ray from the Z axis (the tilt angle in the ideal orientation) when there is no tilt between the Z axis and the lattice plane (115) is α ₁₁₅ = 15.793 ° as shown in Table 1. It is. The tilt angle α ₁₁₅ from the Z axis of the actually detected diffraction X-ray diffraction can be calculated as follows using this Δθ _Y and the tilt angle in the ideal orientation.
α ₁₁₅ = Δθ _Y +15.793

<4. Determination of diffraction line direction by half shutter>
Next, ROI (region of interest) is set to the channel near the analyzed energy, and the diffraction intensity of the set region is monitored.

  As shown in FIG. 10A, the half shutter 14 is fixed in a closed state, and the sample 10 is rotated in-plane (rotated about the z-axis) to perform φ angle scanning. A 115-reflection diffracted X-ray diffraction spot P (diffracted X-ray incident center spot) incident on the sensitive surface 13 a of the X-ray detector 13 with the in-plane rotation of the sample 10 is illustrated with respect to the half shutter 14. 10 (a) relative movement to the left. When the sample 10 rotates in-plane by Δφ, the half shutter 14 covers the diffraction spot P.

By this φ angle scanning operation, an intensity profile having a step function shape as shown in FIG. Then, the scan angle Δφ moved from the reference angle φ before scanning until the X-ray intensity level is halved becomes the deviation angle from the tilt angle of the diffracted X-rays in the ideal direction. By taking this deviation angle Δφ into consideration, the direction of the diffraction X-ray φ ₁₁₅ can be obtained.
The position of the diffraction spot can also be obtained from a peak value obtained by differentiating a step function intensity profile as shown in FIG.

With the above operation and measurement, α ₁₁₅ and φ ₁₁₅ can be obtained. The 115 reflection diffraction vector (that is, the surface normal vector V ₁₁₅ ) can be determined by α ₁₁₅ and φ ₁₁₅ . The diffraction vector can be calculated by substituting α ₁₁₅ and φ ₁₁₅ obtained as described above into α and φ in equation (6) described later.

Similarly, the operation and measurement shown in the above items 2 to 4 are performed with the X-axis of the sample directed in the y-axis direction of the measuring apparatus, and by examining α _1-15 and φ _1-15 , V _1-15 Can be determined.
As a reference for the φ angle, the Z-axis direction is set to zero. Then, φ _1-15 is a value near zero degrees, and φ ₁₁₅ is a value near 90 °.

  Here, the above-described setting of the ROI will be described. When the X-ray detected by the X-ray detector (SDD) 13 is converted into an electric pulse and then analyzed by a multi-channel pulse height analyzer, it is shown with an energy peak profile as shown in FIG. “Setting an ROI for a channel in the vicinity of the analyzed energy” means setting an upper limit and a lower limit of an energy peak and measuring an integrated value of the count number of X-ray pulses sandwiched therebetween. If step movement of the φ angle and counting of X-ray pulses are repeated, the φ angle versus X-ray intensity profile shown in FIG. 10B is obtained. Even if another reflection is mixed into the sensitive surface (X-ray detection surface) of the X-ray detector (SDD) 13, the energy is different, so by setting the ROI and detecting only the X-rays in that region The φ adjustment is not confusing.

なお、図１２において、符号ｍの破線は、Ｖ_ｈｋｌのＸＹ平面への投影線であり、また回折Ｘ線ｋのＸＹ平面への投影線でもある。 <5. Calculation of diffraction vector>
As shown in FIG. 12, the diffraction vector V can be calculated by the following unit vector using coordinates (x, y, z) representing the sample.

In FIG. 12, a broken line with a symbol m is a projection line of V _hkl onto the XY plane, and is also a projection line of the diffracted X-ray k onto the XY plane.

測定した指数は既知なので、計算するだけである。
ここで、Ｖとｈの間には、次の関係がある。

<6. Determination of orientation matrix U>
On the other hand, the surface normal vector (exponential vector) of the corresponding lattice plane (hkl) expressed by crystal axis coordinates (a, b, c) is a unit vector and is expressed as follows.

Since the measured index is known, it is only calculated.
Here, there is the following relationship between V and h.

The transformation matrix U connecting both V and h is a 3 × 3 orthonormal matrix called an orientation matrix.
The determination of U requires a set of three linearly independent vectors. Therefore, a set of three vectors is generated by the following procedure based on the measured two sets V ₁ , h ₁ and V ₂ , h ₂ .
This method is called a two-reflection method. A method of determining U by the two-reflection method is already known, and is disclosed in Non-Patent Document 1, for example.

In this case, V ₁ = V _1-15 , h ₁ = h _1-15 , V ₁ = V ₁₁₅ , h ₁ = h ₁₁₅ and the following calculation may be executed.
First, as shown in FIG. 13A, a vector product of V ₃ and h ₃ is generated from a vector product of V ₁ and V _{2 and} a vector product of h ₁ and h ₂ . Convert this into a unit vector,
V ₃ = V ₁ × V ₂ / | V ₁ × V ₂ |
h ₃ = h ₁ × h ₂ / | h ₁ × h ₂ |
Get.

Further, since the measurement value has an error, in order to avoid confusion in the subsequent calculation, as shown in FIG. 13B, h ₄ corresponding to V ₄ orthogonal to V ₁ and V ₃ is set. Is generated as follows.
V ₄ = V ₃ × V ₁
h ₄ = h ₃ × h ₁
The order of vector products is as shown by arrows in FIGS. 13 (a) and 13 (b).

を得る。
Ｖ＝（Ｖ_１，Ｖ_３，Ｖ_４）
Ｈ＝（ｈ_１，ｈ_３，ｈ_４）
とすると、（９）式は次のようになる。

これを次のように解いてＵを決定する。

このようにしてＵが決定できれば、あらゆる指数の格子面に対してその格子面法線ベクトルが、（８）式を用いて試料を代表する座標(Ｘ，Ｙ，Ｚ)で計算できる。 Using V ₁ , V ₃ , V ₄ and h ₁ , h ₃ , h ₄ obtained in this manner and orthogonal to each other,

Get.
V = (V ₁ , V ₃ , V ₄ )
H = (h ₁ , h ₃ , h ₄ )
Then, the equation (9) becomes as follows.

This is solved as follows to determine U.

If U can be determined in this way, the lattice plane normal vector can be calculated with respect to the lattice plane of any index using the coordinates (X, Y, Z) representing the sample using the equation (8).

<7. Calculation of angle required for crystal orientation inspection and correction processing>
Using the orientation matrix U determined in the above item 6, the surface method of an arbitrary lattice plane in the sample coordinates (x, y, z) by the exponent vector calculated by the expression (7) and the expression (8) Line vectors can be calculated.

Since the main surface of the wafer or ingot is (001) and the direction of attaching an orientation mark such as a notch or orientation flat is <110>, when calculating h ₀₀₁ and h ₁₁₀ using equation (7), V ₀₀₁ and V ₁₁₀ are It can be calculated as follows using equation (8).

Assuming that the calculated X component of V ₀₀₁ is V _X , the Y component is V _Y , and the Z component is V _Z , the inclination angle δ _X of the (001) XZ section and the inclination angle δ _{Y of the} YZ section of the principal surface are , (14) and (15). Furthermore, the maximum inclination angle α and the direction angle β on the XY plane can be calculated by the equations (16) and (17) (see FIG. 14).
In FIG. 14, the Y axis is the direction of an orientation mark such as a notch or orientation flat, and the broken line n is a projection line of V ₀₀₁ onto the XY plane.

Further, regarding the orientation direction of the orientation flat or notch, assuming that the calculated X component of V ₁₁₀ is N _X , the Y component is N _Y , and the Z component is N _Z , the angle ε of FIG. 14 is calculated by Equation (18). be able to.

  If there are other required angles, any angle can be calculated using these components.

[Other Embodiments]
In addition, this invention is not limited to embodiment mentioned above, A various deformation | transformation implementation and application implementation are possible in the range which does not change the summary of invention.
For example, it can also be implemented by the following method.

<Parallel processing with two X-ray detectors>
As shown in FIG. 15, two X-ray detectors 13 are mounted on the measurement apparatus, one X-ray detector 13 detects 115 reflection, and the other X-ray detector 13 detects 1-15 reflection. . As a result, the operation for _obtaining α ₁₁₅ , φ ₁₁₅ and α _1-15 , φ _1-15 and the measurement can be performed simultaneously, and the time required for the measurement process can be further reduced.

この検出系を、１−１５反射の位置にも配置して２チャンネルで運用すれば、測定時間をいっそう短縮することが可能となる。 <Determination of diffraction line direction by half shutter>
In the item 4 above, the diffraction line direction φ ₁₁₅ is detected by rotating the sample 10 in-plane (rotating around the z-axis) and scanning the φ angle, but as shown in FIG. the sensible surface 13a of the sample 10 and the X-ray detector fixed, the half-shutter 14 as shown in FIG. (b) instead be to moved parallel to the x-axis, a direction phi ₁₁₅ of the diffracted X-rays You may ask for it. That is, as the half shutter 14 is moved in parallel with the x-axis, the half shutter 14 eventually covers the diffraction spot P of 115 reflected diffraction X-rays, and a step function-like intensity profile as shown in FIG. can get. The position s of the diffraction line can be examined by processing the intensity profile.
If the distance from the X-ray incident point O on the sample surface 10a to the half shutter is L, Δφ can be calculated by the following equation.

If this detection system is also arranged at the position of 1-15 reflection and operated with two channels, the measurement time can be further shortened.

10: Sample, 10a: Sample surface, 11: X-ray source, 12: Collimator, 13: X-ray detector, 13a: Sensitive surface (X-ray detection surface), 14: Half shutter,
203: crystal habit line, 204: marking line, 214: notch

Claims (3)

An X-ray crystal orientation measuring method comprising the following steps (a) to (e):
(A) irradiate X-rays perpendicular to the sample surface of a single crystal sample in which the approximate orientation of the main lattice plane and the approximate direction to which the orientation mark should be attached are known;
Two or more lattice planes with known indices other than the main lattice plane in the single crystal sample are used as measurement target lattice planes.
Set the reference position in the theoretical direction that the diffracted X-rays will be reflected from the measurement target lattice plane,
A semiconductor X-ray detector is arranged at the reference position, and the energy of the diffracted X-ray reflected from the measurement target lattice plane is detected by the semiconductor X-ray detector.
(B) Based on the energy of the diffracted X-ray detected by the semiconductor X-ray detector, the Bragg angle of the diffracted X-ray reflected from the lattice surface to be measured is obtained, and the single crystal sample includes the orbit of the diffracted X-ray An inclination angle α of the measurement target lattice plane in a plane perpendicular to the sample surface is calculated from the obtained Bragg angle.
(C) A partial area of the sensitive surface of the semiconductor X-ray detector disposed at the reference position is covered with a shielding plate, and the shielding plate, the sample, and the semiconductor X-ray detector are arranged as a sample of the single crystal sample. Relative movement in the direction of rotation in the plane, and based on the change in the intensity of the diffracted X-ray detected by the semiconductor X-ray detector at that time, the tilt angle φ in the sample plane rotation direction of the measurement target lattice plane is calculated To do.
(D) A diffraction vector for the measurement target lattice plane is calculated based on the obtained inclination angles α and φ.
(E) An orientation of an arbitrary lattice plane in the single crystal sample is obtained based on diffraction vectors calculated for the two or more measurement target lattice planes. The single crystal sample is a Si single crystal sample with a plane orientation (001), and the lattice plane to be measured is at a position 90 ° symmetrical to the lattice plane (115) and the lattice plane (115) in the in-plane rotation direction. The procedure (a) to (d) above is performed for the diffracted X-ray reflected from the lattice planes (115) and (1-15) by selecting the lattice plane (1-15) to be arranged. The X-ray crystal orientation measuring method according to claim 1, wherein the orientation of an arbitrary lattice plane is obtained in accordance with the procedure (e). The shielding plate is a half shutter that shields a half region in the direction of rotation in the sample plane of the single crystal sample with respect to the sensitive surface in the semiconductor X-ray detector arranged at the reference position. The X-ray crystal orientation measuring method according to claim 2.

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