JP2014122860A - Crystal orientation measurement jig for monocrystal wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crystal orientation measurement jig that is able to easily measure the crystal orientation of even a monocrystal wafer that has an off-angle.SOLUTION: A crystal orientation measurement jig for a monocrystal wafer 50 fitted in an X-ray diffraction device that measures the crystal orientation of the monocrystal wafer 50 comprises: a rotation mechanism that uses, as a center point 61, an X-ray incident part of a target measurement surface present on a flat surface including an incidence X-ray 51, which is incident on the target measurement surface of the monocrystal wafer 50, and a diffraction X ray 52, which is diffracted by the monocrystal wafer 50, and that rotates and displaces the monocrystal wafer 50 having, as a rotation axis, a straight line passing through the center point 61 and intersecting the flat surface in perpendicular; and an inclination mechanism (gonio stage 56) that uses the center point 61 as its fulcrum and inclines the target measurement surface of the monocrystal wafer 50 with respect to the flat surface, thereby displacing the target measurement surface so that a diffraction surface 60 of the monocrystal wafer 50 has a perpendicular position relation with the flat surface.

Description

  The present invention relates to a single crystal wafer crystal orientation measuring jig incorporated in an X-ray diffraction apparatus for measuring the crystal orientation of a single crystal wafer and fixing a single crystal wafer for measurement. The present invention relates to an improvement in a crystal orientation measuring jig that can easily measure the crystal orientation of a crystal wafer.

  Crystal orientations of semiconductor single crystals such as silicon, gallium arsenide, and gallium phosphide used in electronic devices such as integrated circuits, light emitting diodes, laser diodes, SAW filters, and oxide single crystals such as lithium tantalate, lithium niobate, and sapphire are Orientation measurement by an X-ray diffractometer is an important task because it greatly affects device characteristics.

  X-ray diffraction is widely used for measuring the orientation of a single crystal wafer, and is mainly divided into measuring the orientation of the principal plane and the orientation flat (hereinafter abbreviated as OF). The principal plane orientation indicates the direction of the crystal orientation in the single crystal wafer plane as the name suggests. Further, the OF orientation indicates the orientation of the crystal orientation in a flat portion formed by cutting the side surface of the single crystal wafer into a straight line, and is used as a positioning reference when the wafer is cut into a device piece.

  For example, a gallium arsenide single crystal wafer is famous for the (100) plane principal plane orientation, and the OF orientation is a {110} cleaved plane. For a lithium tantalate single crystal wafer, the major plane orientation is The 36 ° RY plane and the OF orientation are famous for the + X plane. In general, the standard of surface orientation is generally within ± 0.5 degrees, but in recent years, the surface orientation of sapphire and the like, which is in great demand for lighting white diode applications, is required to be less than ± 0.1 degrees. There is also.

  However, while the principal plane orientation represents an absolute plane, the OF orientation does not necessarily indicate an absolute plane. The principal plane orientation may have an angle with respect to the diffraction plane. This is generally called a wafer having an off angle. For example, in the case of a gallium arsenide single crystal wafer, when the principal plane orientation is turned off twice from (100) in an arbitrary direction, (100) and {110} are planes that intersect at 90 degrees, so that O.F. As a surface obtained by vertically viewing, is not a surface parallel to {110}. In this case, OF is often indicated as the {110} direction when the two-off surface (100), which is an absolute surface, is viewed vertically.

  By the way, when manufacturing a single crystal wafer, the following processes are common.

  As shown in FIG. 1, first, after a single crystal ingot 103 grown by the Czochralski method or the like is formed like an ingot 105, the ingot 105 is cut by a multi-wire saw 106, and a single crystal wafer 107 is formed at a time. obtain. Since the single crystal wafer 107 is easily chipped as it is, the outer periphery is chamfered using a chamfering machine to obtain a chamfered wafer 108. The chamfering is mechanically performed following the outer peripheral shape of the single crystal wafer 107. In FIG. 1, reference numeral 101 denotes a pulling shaft, reference numeral 102 denotes a seed crystal, and reference numeral 104 denotes a raw material.

  Since the ingot 105 is provided with a surface 105a and an OF 105b serving as a reference for the multi-wire saw 106 in advance, the main surface orientation 107a and the OF orientation 107b of the single crystal wafer 107 are 1 Next, it is determined when the ingot 105 is formed. The orientation of the surface 105a and the orientation of the OF 105b in the ingot 105 provided in advance are also determined by measurement with an X-ray diffractometer.

  However, the main surface orientation 107a of the single crystal wafer 107 may be displaced due to a mechanical accuracy problem in the wire saw 106, and the OF orientation 107b may be displaced due to a mechanical accuracy problem in chamfering. Therefore, the main surface orientation 107a must be measured and confirmed again with an X-ray diffractometer after wire saw cutting and the OF orientation 107b after chamfering.

  Hereinafter, the measurement of the principal plane orientation by the X-ray diffractometer will be specifically described with reference to FIG.

  2A and 2B are explanatory views showing the measurement state of the principal plane orientation (100) in the single crystal wafer 20. FIG. As shown in FIGS. 2 (A) and 2 (B), the single crystal wafer 20 is loaded on the sample stage 23, and a method of fixing the single crystal wafer 20 by vacuum suction that is simple and easy to use is common. Then, incident X-rays 21 are incident on the surface to be measured of the single crystal wafer 20 as shown in FIGS. 2A and 2B, and the diffracted X-rays 22 diffracted by the single crystal wafer 20 enter the detector 24. Observed. Further, the sample stage 23 is rotated, and the position of the sample stage 23 where the peak of the X-ray dose is counted by the detector 24 is searched. Since the θ angle when the position of the detector 24 is set to 2θ is determined from the interplanar spacing of the crystal, the desired diffraction surface, and the Bragg equation, the diffraction surface can be determined by reading how much the sample stage 23 has shifted. Measured as deviation from.

  3 (A) and 3 (B) are explanatory views showing the measurement state of the OF orientation in the single crystal wafer 30, except that the stacking direction of the single crystal wafer 30 is changed. ) And (B). In FIGS. 3A and 3B, reference numeral 31 denotes incident X-rays, reference numeral 32 denotes diffracted X-rays, reference numeral 33 denotes a sample stage, and reference numeral 34 denotes a detector.

  By the way, the sample stage shown in FIG. 2 and FIG. 3 has a single crystal wafer with respect to a plane including incident X-rays incident on the surface to be measured of the single crystal wafer and diffracted X-rays diffracted by the single crystal wafer. This is based on the premise that the diffractive surfaces are perpendicular to each other. However, the diffractive surface of the single crystal wafer to be measured may have an oblique angle with respect to the above plane, and as a result, the diffracted X-ray is angled and deviated from the detector, making it impossible to measure. is there. This is because the X-ray diffractometer is arranged on the assumption that the incident X-ray and the detector for detecting the diffracted X-ray exist on the same plane. This phenomenon occurs when the principal plane orientation of the single crystal wafer is greatly deviated from the diffraction plane. That is, it occurs when the single crystal wafer having the off-angle is set as a measurement target.

  The above phenomenon will be specifically described with reference to FIGS.

  The single crystal wafer 40 is made of gallium arsenide, has a main surface orientation with an off angle of (100) to 15 °, and the OF direction is {110}. When the OF orientation is measured with this wafer, the diffractive surface {110} of the single crystal wafer 40 corresponds to the diffractive surface 43 shown in FIG. This is because (100) and {110} intersect at right angles as shown in FIG. In this state, the incident X-ray 41 is irradiated obliquely to the {110} diffraction surface 43 (the diffraction surface 43 with respect to a plane including the incident X-ray 41 and the diffraction X-ray 42 diffracted by the single crystal wafer 40). Therefore, the diffracted X-ray 42 diffracted by the single crystal wafer 40 jumps up apparently and deviates from the detector 44.

  In order to avoid this problem, the diffraction plane of the single crystal wafer is perpendicular to the plane containing the incident X-rays incident on the measured surface of the single crystal wafer and the diffracted X-rays diffracted by the single crystal wafer. For example, in the invention described in Patent Document 1, a method of preparing a plurality of types of sample tables having various angles in advance and replacing the plurality of types of sample tables at any time is introduced. ing. Although the work is simplified by a mechanism that partially replaces the sample stage, it is necessary to prepare a plurality of types of sample stages with various angles in advance, and it is not possible to deal with those not prepared in advance. In addition, there is still a problem that the work for partially exchanging the sample stage may cause backlash due to wear and an error may occur.

JP 2001-324457 A

  The present invention has been made paying attention to such problems, and the object of the present invention is to provide a crystal orientation measuring jig capable of easily measuring the crystal orientation of a single crystal wafer having an off angle. It is to provide.

That is, the invention according to claim 1
In a jig for measuring crystal orientation of a single crystal wafer, which is incorporated in an X-ray diffractometer that measures the crystal orientation of a single crystal wafer and fixes the single crystal wafer for measurement,
With the X-ray incident part of the measurement surface existing on the plane including the incident X-ray incident on the measurement surface of the fixed single crystal wafer and the diffraction X-ray diffracted by the single crystal wafer as a center point, A rotation mechanism that rotates and displaces the single crystal wafer around a straight line passing through the center point and perpendicular to the plane as a rotation axis, and tilting the measurement surface of the single crystal wafer with the center point as a fulcrum and the plane. And a tilt mechanism that displaces the diffraction plane of the single crystal wafer so as to be in a positional relationship perpendicular to the plane.

The invention according to claim 2
In the jig for measuring a crystal orientation of a single crystal wafer according to claim 1,
A sample stage having a rotation surface that rotates about the rotation axis, a concave member that is placed on the rotation surface of the sample stage and has a concave surface with a circular arc cross section on the surface side, and a cross-sectional circle that fits the concave surface A goniometer comprising a convex member having an arc-shaped convex surface on the back surface side, and a wafer fixing member mounted on the surface side of the convex member on the goniometer and fixing a single crystal wafer for measurement. To do.

A jig for measuring crystal orientation of a single crystal wafer according to the present invention,
With the X-ray incident part of the measurement surface existing on the plane including the incident X-ray incident on the measurement surface of the fixed single crystal wafer and the diffraction X-ray diffracted by the single crystal wafer as a center point, A rotation mechanism that rotates and displaces the single crystal wafer around a straight line passing through the center point and perpendicular to the plane as a rotation axis, and tilting the measurement surface of the single crystal wafer with the center point as a fulcrum and the plane. And a tilt mechanism for displacing the diffractive surface of the single crystal wafer so as to be in a positional relationship perpendicular to the plane.

  For this reason, compared with the invention described in Patent Document 1, it is not necessary to prepare a plurality of types of sample stands in advance. Further, since the work for exchanging the sample stage itself is not necessary, it is only necessary to actuate the rotation mechanism and the tilt mechanism of the crystal orientation measuring jig, so that the plane orientation can be measured more quickly.

  Furthermore, the crystal orientation measurement jig according to the present invention is overwhelming in comparison with the prior art in situations where the orientation measurement is performed while searching for the off angle when measuring the orientation of a single crystal wafer with an unknown off angle. In addition, the operation is easy and efficient.

Explanatory drawing which shows the process of manufacturing a single crystal wafer. FIG. 2A shows a measurement state of the principal plane orientation (100) in the single crystal wafer 20 according to the prior art, FIG. 2A is a side view from the arrow A in FIG. 2B, and FIG. The top view which shows the measurement state of direction (100). FIG. 3A shows a state of measurement of the OF orientation in the single crystal wafer 30 according to the prior art, FIG. 3A is a side view from an arrow A in FIG. 3B, and FIG. FIG. 6 is a plan view showing a measurement state of an orientation. FIG. 4 shows a method for measuring the OF orientation according to the prior art of a single crystal wafer 40 in which the principal plane orientation has an off angle of (100) to 15 ° and the OF direction is {110}. A) is a plan view of the single crystal wafer 40, FIG. 4B is an explanatory view of the diffractive surface 43 of the single crystal wafer 40, and FIG. 4C is an adverse effect of the above-described measuring method of the OF orientation according to the prior art. FIG. FIG. 5A shows a method for measuring the OF orientation using a crystal orientation measuring jig for a single crystal wafer according to the present invention, and FIG. 5A is a side view from the arrow A in FIG. (B) is a side view from arrow B of FIG. 5 (C), and FIG. 5 (C) is a measurement state of the OF orientation using the crystal orientation measuring jig of the single crystal wafer according to the present invention. FIG.

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

  First, as shown in FIGS. 5A and 5B, the jig for measuring crystal orientation of a single crystal wafer according to the present invention includes a sample stage 55 having a rotating surface (not shown), and the above-described sample stage 55. A goniometer 56 comprising a concave member 57a having a concave surface with an arcuate cross section on the surface side and a convex member 57b having a convex surface with an arcuate cross section that fits the concave surface on the back surface side; 56 is mounted on the surface side of the convex member 57b, and a main part is constituted by a wafer fixing member 59 for fixing the measurement single crystal wafer 50 by vacuum suction. The wafer fixing member 59 includes an angle meter. 58 is provided, and the goniometer 56 is provided with a fixing screw 56a.

  In addition, as shown in FIGS. 5A and 5C, this crystal orientation measuring jig has incident X-rays 51 incident on the surface to be measured of the single crystal wafer 50 and diffraction diffracted by the single crystal wafer 50. The X-ray incident part of the surface to be measured existing on the plane including the X-ray 52 is set as a center point 61 (see FIG. 5B), and a straight line passing through the center point 61 and perpendicular to the plane is used as a rotation axis. A rotation mechanism for rotating and displacing the single crystal wafer 50 (consisting of a rotation surface of the sample stage 55 rotating around the rotation axis), and the single crystal wafer 50 with the center point 61 as a fulcrum and with respect to the plane. The diffracting surface 60 of the single crystal wafer 50 is tilted with respect to the measured surface of the single crystal wafer 50, and the incident X-ray 51 incident on the measured surface of the single crystal wafer 50 and the diffracted X-ray diffracted by the single crystal wafer 50. Perpendicular to the plane containing 52) The goniometer 56 is composed of a tilting mechanism (a concave member 57a having a concave surface having a circular arc section on the front surface side and a convex member 57b having a convex surface having a circular arc shape to be fitted to the concave surface on the back surface side. Comprising).

  The single crystal wafer 50 is made of gallium arsenide, has a main surface orientation with an off angle of (100) to 15 °, and the OF direction is {110}.

  The single crystal wafer 50 is sucked and fixed by the wafer fixing member 59 and loaded on the gonio table 56. Moreover, the gonio stand 56 is comprised by the concave surface member 57a which has a concave surface of circular arc shape on the surface side as mentioned above, and the convex surface member 57b which has the convex surface of circular arc shape which fits the said concave surface on the back surface side. In addition, by sliding the convex member 57b on the concave surface of the concave member 57a, the incident X-ray 51 incident on the surface to be measured of the single crystal wafer 50 and the diffracted X-ray 52 diffracted by the single crystal wafer 50 are obtained. It is possible to tilt the surface to be measured of the single crystal wafer 50 with the X-ray incident part (center point 61) of the surface to be measured as a fulcrum with respect to a plane including The inclination angle of the single crystal wafer 50 with respect to the plane can be easily determined by an angle meter 58 attached to the wafer fixing member 59, and can be arbitrarily determined by a fixing screw 56a attached to the gonio table 56. Can be fixed at an angle. At this time, it is important that the X-ray incident part of the surface to be measured existing on the plane is the central point 61 and the central point 61 is inclined as a fulcrum. The center point 61 is on a plane including the incident X-ray 51 incident on the surface to be measured and the diffracted X-ray 52 diffracted by the single crystal wafer 50, and even when the goniometer 56 is angled, It is possible to reliably irradiate the surface to be measured of the single crystal wafer 50 with X-rays.

  The 15 ° off-angle of the single crystal wafer 50 is corrected by the action of the goniometer 56 and the goniometer 58, and the diffraction surface 60 in the OF direction {110} A condition that is perpendicular to the incident X-ray 51 incident on the measurement surface and the plane containing the diffracted X-ray 52 diffracted by the single crystal wafer 50 is satisfied. As a result, the incident X-rays 51 existing on the plane are irradiated under the condition satisfying the positional relationship perpendicular to the diffraction surface 60 in the OF direction {110}, as shown in FIG. As a result, the diffracted X-rays do not jump up and are reliably captured by the detector 54, and the azimuth can be measured.

  Note that FIG. 5 illustrates the measurement of the OF orientation, but the effect is the same when the principal plane orientation of a single crystal wafer is measured, except that the orientation of the single crystal wafer is different.

  Examples of the present invention will be described below.

  The crystal orientation measurement jig shown in FIG. 5 was applied to perform the orientation measurement operation of the single crystal wafer having an off angle. The time required for adjusting the off angle was 10 seconds.

  On the other hand, when the jig described in Patent Document 1 was used, it took 30 seconds to adjust the off angle, and the superiority of the crystal orientation measuring jig according to the example was clear.

  Unlike the prior art, the crystal orientation measuring jig of the present invention having a rotation mechanism and an inclination mechanism does not need to prepare a plurality of types of sample tables in advance, so that the orientation measurement of a single crystal wafer with an unknown off angle is performed. It has industrial applicability to be used in such cases.

20 single crystal wafer 21 incident X-ray 22 diffracted X-ray 23 sample stage 30 single crystal wafer 31 incident X-ray 32 diffracted X-ray 33 sample stage 34 detector 40 single crystal wafer 41 incident X-ray 42 diffracted X-ray 43 diffraction surface 44 detection Instrument 50 Single crystal wafer 51 Incident X-ray 52 Diffraction X-ray 54 Detector 55 Sample stage 56 Goniometer 56a Fixing screw 57a Concave member 57b Convex member 58 Angle meter 59 Wafer fixing member 60 Diffraction surface 61 Center point 101 Pulling shaft 102 Seed crystal 103 Single Crystal Ingot 104 Raw Material 105 Ingot 105a Reference Surface 105b Orientation Flat (O.F.)
106 Wire saw 107 Single crystal wafer 107a Main surface orientation 107b OF orientation 108 Chamfered wafer

Claims (2)

In a jig for measuring crystal orientation of a single crystal wafer, which is incorporated in an X-ray diffractometer that measures the crystal orientation of a single crystal wafer and fixes the single crystal wafer for measurement,
With the X-ray incident part of the measurement surface existing on the plane including the incident X-ray incident on the measurement surface of the fixed single crystal wafer and the diffraction X-ray diffracted by the single crystal wafer as a center point, A rotation mechanism that rotates and displaces the single crystal wafer around a straight line passing through the center point and perpendicular to the plane as a rotation axis, and tilting the measurement surface of the single crystal wafer with the center point as a fulcrum and the plane. A jig for measuring a crystal orientation of a single crystal wafer, comprising a tilt mechanism for displacing the diffraction plane of the single crystal wafer so as to be in a positional relationship perpendicular to the plane.   A sample stage having a rotation surface that rotates about the rotation axis, a concave member that is placed on the rotation surface of the sample stage and has a concave surface with a circular arc cross section on the surface side, and a cross-sectional circle that fits the concave surface A goniometer comprising a convex member having an arc-shaped convex surface on the back surface side, and a wafer fixing member mounted on the surface side of the convex member on the goniometer and fixing a single crystal wafer for measurement. The jig for measuring a crystal orientation of a single crystal wafer according to claim 1.

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