JPH03225266A - Method for inspecting cut face - Google Patents

Abstract

PURPOSE:To make it possible to inspect a cut face while fixing a sample on a cutting device by shielding a part of X rays made incident upon the cut face by an X-ray shield and moving the X-ray shield to change an incident angle. CONSTITUTION:The cut face 2 of the sample 1 makes an angle alpha with a crystal grating face 3. In this case, the divergent angle of X rays radiated from an X-ray source 4 is regulated by a regulation slit 41 and the sample 1 is irradiated with divergent X rays Xi having the devergent angle delta. When the X-ray shield 5 is moved by an X-ray shield moving means 51 and the shielding range is gradually reduced, diffracted X rays Xr due to the grating face 3 starts to be generated. The diffracted X rays Xr are detected by an X-ray detector 6 and its intensity is suddenly increased up to the maximum and then made constant. Thereby, the angle alpha can be found out from an equation alpha = thetaB - theta by finding out the incident angle theta obtained at the time of indicating 1/2 the fixed intensity of the diffracted X rays because the diffracting angle thetaB is known.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for inspecting a cut surface of a crystalline sample that can be used in inspecting a cut surface of a crystalline wafer or the like used in the field of semiconductor industry.

[Prior Art] Crystalline wafers are generally manufactured by cutting a single crystal block.

In this case, it is required that this cut surface (cut surface) and a specific crystal lattice plane have a specific angular relationship depending on the application. If this angular relationship is not within a predetermined tolerance range, the desired function cannot be achieved.

For this reason, conventionally, crystalline wafers manufactured by cutting crystal blocks are inspected by a cut surface inspection device, and the angle between the cut surface and a specific crystal lattice plane falls within a predetermined tolerance range. A check is made to see if it exists.

This cut surface inspection device applies the principle of X-ray diffraction to measure the diffraction angle of a specific crystal lattice plane of the crystalline wafer, thereby detecting the angle between the cut surface and the specific crystal lattice plane. This is what we seek. That is, as shown in FIG. 2, a cut surface 1 of a sample 101 such as a crystalline wafer
02 is irradiated with incident X-rays X1, and diffracted X-rays X generated by being diffracted by a specific crystal lattice plane 103 of the sample 101 satisfying Bragg's diffraction conditions are observed. Now, the angle between the cut plane 102 and the specific crystal lattice plane 103 is α, the angle between the incident X-ray X and the cut plane 102 is θ, and the specific crystal lattice plane 103 and the incident X-ray The angle between X and the diffracted X-ray Xr is θB (=diffraction angle; known)
shall be.

Then, as is clear from FIG. 2, the angle α between the cut plane 102 and the specific crystal lattice plane 103 can be determined by the following formula: α2θ−08 (1). Therefore, the above (
α can be found by actually measuring θ in equation 1).

Conventionally, as a method for determining this θ, for example, the well-known
Using a line goniometer or the like, the cut plane 102 is changed with respect to the direction of the irradiated X-rays, and the crystal lattice plane 10
The incident X when the diffracted X-ray X of 3 is detected
The angle of the line X+ with respect to the cut surface 102 was measured and determined as θ.

[Problems to be Solved by the Invention] Incidentally, in order to inspect a cut surface using the above-described conventional method, it is necessary to attach the sample 101 to an X-ray goniometer or the like for measurement. In this case, if the sample 101 is in the form of a slice, it can be easily attached to a goniometer for measurement.

However, when it is desired to inspect the cut surface of a crystal mass before it is formed into slices, it is extremely difficult to attach the crystal mass to the goniometer, making measurement extremely difficult using the conventional method described above. . In addition, in recent years, as the demand for automation of cutting crystal blocks has increased,
It has become necessary to inspect the cut surface while the crystal mass remains attached to the cutting device. Conventional methods have not been able to meet this request.

The present invention has been made against the above-mentioned background, and an object of the present invention is to provide a cut surface inspection method that allows a cut surface to be inspected while a sample is fixed to a cutting device or the like using a relatively simple method. This is what I did.

[Means for Solving the Problems] The present invention solves the above problems by having the following configuration.

By detecting the diffraction X-rays generated by a specific crystal lattice plane of the sample when the cut surface of the crystalline sample is irradiated with X-rays, and determining the incident angle of the X-rays irradiating the cut surface at that time, In the cut surface inspection method for determining the angle between the cut surface of the sample and the specific crystal lattice plane, the incident angle of the X-rays irradiated onto the cut surface with respect to the cut surface has a predetermined angular range, and substantially Dotted X
Using divergent X-rays emitted from a radiation source, the direction of incidence of the divergent X-rays on the cut plane is set in advance so that one of the divergent X-rays satisfies the diffraction conditions according to the specific crystal lattice plane. Then, a portion of the X-rays incident on the cut surface of the divergent X-rays is blocked by an X-ray shield, and the X-ray shield is moved to block the cut surface of the divergent X-rays. changing the range or incident angle of the incident
the position of the X-ray shield when the rays are generated and reach a predetermined intensity, or the position of the X-ray shield when diffracted X-rays by the specific crystal lattice plane have been generated from the beginning of the movement of the X-ray shield; The positions of the X-ray shields are determined when the intensity of the diffracted X-rays starts to decrease and reaches a predetermined intensity, and the X-rays relative to the cut plane when the diffracted X-rays are generated by the specific crystal lattice plane from this position are determined. A configuration characterized by finding the angle of incidence of a line.

"Operation" In the above configuration, if no diffracted X-rays are generated by the specific crystal lattice plane at the beginning of the movement of the X-ray shield, when the diffracted X-rays are generated and reach a predetermined intensity, If diffracted X-rays are generated by the specific crystal lattice plane from the position of the X-ray shield or from the beginning of movement of the X-ray shield, the intensity of the diffracted X-rays begins to decrease and reaches a predetermined intensity. By determining the positions of the Xli shielding objects when the Xli shielding object becomes , it is possible to determine from these positions the incident angle of the X-rays with respect to the cut plane when the diffracted X-rays are generated by the specific crystal lattice plane.

That is, since any of the divergent X-rays is preset so as to satisfy the diffraction conditions of the specific crystal lattice plane, for example, most of the divergent X-rays can be blocked by the X-ray shield. When the cutoff range is gradually reduced, diffracted X-rays are generated by the specific crystal lattice plane at a certain position, and the intensity of the diffracted X-rays increases rapidly and then reaches a constant value. The position of the X-ray shield at this time depends on the angle of the incident X-ray when the diffracted X-ray is generated by the specific crystal lattice plane. Therefore, for example, when the intensity of the diffracted X-ray is 1/2 of the constant intensity,
The angle between the cut surface of the sample and the incident X-ray can be determined from the position of the radiation shield. Furthermore, for example, if the divergent X-rays are not initially blocked by the X-ray shield and the blocking range is gradually increased, the initially occurring diffracted X-rays by the specific crystal lattice plane may be It starts to decrease and disappears. Therefore, similarly to the above, the angle between the cut surface of the sample and the incident X-ray can be determined from the position of the X-ray shield when the intensity is 1/2 of the intensity of the diffracted X-ray. Further, for example, by using an X-ray shield having a slit-shaped X-ray passage hole and moving this X-ray shield, the incident angle of the X-rays incident on the cut surface is scanned, and the diffracted X-ray The angle between the cut surface of the sample and the incident X-ray can also be determined by determining the position of the X-ray shield when the ray shows the maximum intensity.

This makes it possible to determine the angle between the cut surface of the sample and a specific crystal lattice plane of the sample. Note that the diffracted X-rays can be easily detected by using an open-type X-ray detector that can detect X-rays over a relatively wide range.

According to this method, there is no need to attach the sample to an X-ray goniometer or the like, and the cut surface can be inspected while the sample is fixed to a cutting device or the like.

[Example] FIG. 1 is an explanatory diagram of a cut surface inspection method according to an embodiment of the present invention, and FIG. 3 is a partially enlarged view of FIG. 1. Hereinafter, one embodiment will be described in detail with reference to these drawings.

In the figure, code 1 is the sample, code 2 is the cut surface of sample 1 (
(cut plane), code 3 is a specific crystal lattice plane of sample 1, code 4
5 is an X-ray source, 5 is an X-ray shield, and 6 is an X-ray detector.

The sample 1 is a crystal block made of a single crystal of silicon or the like. This sample 1 has a crystal lattice plane 3 making an angle α with respect to the cut plane 2 of the sample 1. The method of this embodiment is to find this α.

Said X-ray source 4 is essentially a point X-ray source;
The divergent X-rays emitted from the slit 41 have their divergence angles regulated by the divergence angle regulating slit 41, and become divergent X-rays Xi having an appropriate divergence angle δ. The angle of incidence of this divergent X-ray Xi on the cut surface 2 of the sample 1 has an angular range H from the maximum θ 2 to the minimum θ 3 .

Further, the specific crystal lattice plane 3 of the sample 1 has the divergence
Of the rays Xi, only the X-rays having an incident angle θ that satisfies the diffraction conditions are diffracted to generate diffracted X-rays X.

The X-ray shield 5 can be moved by an X-ray shield driving means 51 in a direction parallel to the cut surface 2 of the sample 1, as shown by an arrow p in the figure. The X-ray shield driving means 51 incorporates a mechanism for moving the X-ray shield 5 and a means for measuring the distance X of the movement. Here, the distance tip 5
The distance is up to 2. Although not shown, a control device including a microprocessor or the like is connected to the X-ray shield driving means 51, and this control device controls the X-ray shield driving means 51 and performs calculations to be described later. It has become.

The X-ray detector 6 is equipped with a detection section having a relatively large area, and even if any of the divergent X-rays X satisfies the diffraction conditions, the diffraction X! !
X, can be detected.

Now, when the above-mentioned relationship exists, the X-ray shield 5 is moved by the X-ray shield driving means 51 to change the blocking range of the divergent X-rays Xi. That is, for example, first, the X-ray shield 5 is moved to the right in the figure to block most of the divergent X-rays X. Next, this is gradually moved to the left to reduce its blocking range.

Then, diffracted X-rays X by the specific crystal lattice plane 3 begin to occur from a certain position and are detected by the X-ray detector 6. The intensity of this diffracted X-ray increases rapidly, reaches a maximum, and then becomes constant. Therefore, the diffraction X which became constant
The position of the X-ray shield when the intensity is 1/2 of the intensity of the ray, that is, from the point O to the tip 52 of the X-ray shield 5.
Let the distance to

The incident angle of the X-ray at this time is the incident angle that satisfies the diffraction conditions. If this angle is θ and the distance from the X-ray source 4 to the point O is a, then tanθ=a/x (2) holds from a simple geometrical relationship. In formula (2), a is a known constant uniquely determined by the positional relationship between the X-ray source 4 and the X-ray shield driving means 51, and
It can be measured by 1. Thereby, θ can be immediately determined by causing the control means to perform a predetermined calculation. As described above, once this θ is determined, α can be determined by calculating α−6!8−θ from the known diffraction angle θB. Note that this calculation can be easily performed by storing the value θ in the control device (not shown) and performing calculations as appropriate.

In addition, contrary to the above, if the divergent X-rays are not initially blocked by the X-ray shield 5 and the blocking range is gradually increased, the initially occurring diffracted X-rays due to the specific crystal lattice plane 3 The line Xr begins to decrease at a certain position and suddenly disappears. In this case, α can also be determined by determining X at this time and performing the same calculation in the same manner as described above.

Note that if the increase or decrease in diffracted X-rays is extremely rapid, the position of the X-ray shield may be set to X immediately at the start of the increase or decrease.

According to this embodiment, there is no need to attach the sample 1 to an X-ray goniometer or the like as in the conventional case, and the cut surface can be inspected while the sample 1 is fixed to a cutting device or the like. Moreover, according to this method, complicated equipment such as X-ray goniometers, etc.
It is flexible to perform cut surface inspection with a relatively simple device without requiring a horizontal device.

Note that the present invention is not limited to the above-mentioned example,
For example, by using an X-ray shield with a slit-shaped X-ray passing hole and moving this X-ray shield, the incident angle of the X-rays incident on the cut surface is scanned, and the diffracted X-rays are The angle between the cut surface of the sample and the incident X-ray can also be determined by determining the position of the X-ray shield when the maximum intensity is exhibited.

[Effects of the Invention] As detailed above, the present invention has an incident angle with respect to the cut surface or a predetermined angle range as the X-rays irradiated to the cut surface, and is substantially a point-shaped X-ray source. The direction of incidence of the divergent X-rays on the cut plane is set in advance so that one of the divergent X-rays satisfies the diffraction conditions by the specific crystal lattice plane. , Blocking a part of the X-rays incident on the cut surface of the divergent X-rays with an X-ray shield, and moving this X-ray shield so that some of the divergent X-rays are incident on the cut surface. changing the incident angle range or incident angle of the X-rays, and if no diffracted X-rays are occurring due to the specific crystal lattice plane at the beginning of the movement of the X-ray shield, the diffracted X-rays are changed;
the position of the X-ray shield when the rays are generated and reach a predetermined intensity, or the position of the X-ray shield when diffracted X-rays by the specific crystal lattice plane have been generated from the beginning of the movement of the X-ray shield; The positions of the X-ray shields when the intensity of the diffracted X-rays begins to decrease and reach a predetermined intensity are determined, and the X-rays relative to the cut plane when the diffracted X-rays are generated by the specific crystal lattice plane from this position are determined. It has a configuration characterized by determining the angle of incidence of a line, and as a result, a cut I/surface inspection method that can inspect the cut surface while the sample is fixed to a cutting device etc. is obtained using a relatively simple method. It is something.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a cut surface inspection method according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of the principle of cut surface inspection, and FIG. 3 is a partially enlarged view of FIG. 1. DESCRIPTION OF SYMBOLS 1... Sample, 2... Cut surface, 3... Specific crystal lattice plane of sample 1, 4... X-ray source, 5... X-ray shield, 6... X-ray detection vessel.

Claims (1)

[Claims] When a cut surface of a crystalline sample is irradiated with X-rays, diffraction X-rays generated by a specific crystal lattice plane of the sample are detected, and the X-rays irradiated onto the cut surface at that time are incident. In the cut surface inspection method for determining the angle between the cut surface of the sample and the specific crystal lattice plane by determining the angle, the incident angle of the X-rays irradiated onto the cut surface with respect to the cut surface falls within a predetermined angular range. using divergent X-rays emitted from a substantially point-like X-ray source, the direction of incidence of the divergent X-rays on the cut surface is such that any of the divergent X-rays is diffracted by the specific crystal lattice plane. The conditions are set in advance to satisfy the conditions, and the X-ray shield partially blocks the X-rays incident on the cut surface of the divergent X-rays, and the X-ray shield is moved. and changing the incident angle range or incidence angle of the X-rays incident on the cut surface among the divergent X-rays, so that diffracted X-rays are generated by the specific crystal lattice plane at the beginning of movement of the X-ray shield. If not, its diffraction
the position of the X-ray shield when the rays are generated and reach a predetermined intensity, or the position of the X-ray shield when diffracted X-rays by the specific crystal lattice plane have been generated from the beginning of the movement of the X-ray shield; The positions of the X-ray shields when the intensity of the diffracted X-rays begins to decrease and reach a predetermined intensity are determined, and the X-rays relative to the cut plane when the diffracted X-rays are generated by the specific crystal lattice plane from this position are determined. A cut surface inspection method characterized by determining the angle of incidence of a line.