JPH04121649A - Sample horizontal type two-crystal x-ray diffraction apparatus - Google Patents

Abstract

PURPOSE:To extremely accurately evaluate a sample over the whole thereof by parallel moving the sample within a horizontal plane using an XY table. CONSTITUTION:The point-like X-rays emitted from the X-ray focus P of an X-ray tube are made monochromatic by the first crystal 10 and incident to a sample 33 to be diffracted or scattered and the intensity of the diffracted X-rays is detected by an X-ray detector 15. An X-axis pulse motor 17 and/or a Y-axis pulse motor 19 is operated to minutely move the whole of a case 21 in parallel within a horizontal plane. The sample 33 placed on a sample stand 31 is parallel moved in the same way by said minute parallel movement. By this method, the incident position of the monochromatic X-rays sent from the first crystal 10 to the sample 33 can be moved to an arbitrary different position and the locking curve at the different position can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a two-crystal X-ray diffraction apparatus in which a sample is held horizontally.

[Prior Art] In recent years, semiconductors formed by growing an epitaxial layer on a single crystal substrate made of gallium arsenide (GaAs)-indium phosphide (InP), etc. have come into wide use. . In this semiconductor,
the integrity of epitaxial layers grown on single crystal substrates;
Controlling film thickness and composition is extremely important.

Conventionally, a so-called rocking curve measurement method has been widely used as a method for evaluating thin film layers on such single crystal substrates.

This rocking curve measurement method involves irradiating X-rays onto a single-crystal substrate sample on which a thin film has been formed, and then diffracting The purpose is to evaluate the integrity of the epitaxial layer by examining the intensity of X-rays or scattered X-rays.

The rocking curve measurement as described above is usually performed on the first
By irradiating a specific point on the sample with X-rays that have been made monochromatic (extracting only one specific wavelength of X-rays) by the crystal, and detecting the rocking curve for that one point, the entire sample can be detected. The conventional method was to estimate the state of the film.

[The problem that the invention tries to solve! ] However, recently, single-crystal substrates, so-called wafers, as samples to be measured have become larger, and simply detecting a rocking curve at one point, as in the past, cannot accurately evaluate the entire sample. The problem arose that it was not possible.

The present invention has been made in view of the above-mentioned problems with conventional X-ray diffraction devices, and it is possible to obtain rocking curves and other X-ray diffraction curves for many points on a sample with only extremely simple operations. The purpose of the present invention is to provide an X-ray diffraction apparatus that can perform

[Means for Solving the Problems] In order to achieve the above object, an X-ray diffraction apparatus according to the present invention irradiates a sample with X-rays made monochromatic by a first crystal, and generates X-rays diffracted by the sample. The Xi1 diffractometer measures the intensity of a sample, and includes a sample stage on which a sample is placed horizontally, and a sample micro-rotation drive means for rotating the sample stage over a predetermined angular range at microstep angles about a first horizontal axis. a rotation frame provided around the sample table at a distance from the sample table; a frame rotation means for rotating the rotation frame around the first horizontal axis; and a rotation frame provided on the rotation frame. a rotary table rotatable about a second horizontal axis parallel to the first horizontal axis; a first crystal provided on the rotary table and rotatable about the second horizontal axis; It has an X-ray tube that is fixedly placed on the rotary table and makes X-rays incident on the 11!1 crystal, and the sample micro-rotation drive means has an XY tube that can be moved in parallel in a horizontal plane. It is characterized by being fixed on the child table.

In this xm diffraction apparatus, it is preferable that the sample stage is tiltable so that parallelism with respect to the first crystal can be adjusted.

Moreover, it is preferable to have a lifting means for raising and lowering the sample mounting surface of the sample stage in the vertical direction.

[Function] The sample is placed horizontally on the sample stage. It is simply placed in place without being glued or clamped.

The sample on the sample stand is irradiated with X-rays while the sample stand is fixed in position. This X-ray is made monochromatic by being diffracted by the first crystal. During this X-ray irradiation, the sample is rotated by the sample fine rotation drive means over a minute angle range, for example, at intervals of several hundred seconds, every minute step angle, for example, 0.5 seconds.
It rotates intermittently every second. During this intermittent micro-rotation of the sample, the intensity of X-rays diffracted or scattered by the sample is measured by an X-ray detector to obtain a target rocking curve or other X-ray intensity curve.

Once the above measurements are completed for one location on the sample.

The sample micro-rotation driving means is translated in parallel on the same horizontal plane by the XY child table. As a result, the incident position of monochromatic X-rays on the sample on the sample stage supported by the sample micro-rotation driving means is changed, and rocking curves and the like at different positions can be obtained.

[Example] FIG. 1 shows an example of a sample horizontal double-crystal method X-ray diffraction apparatus according to the present invention.

In the same figure, a frame stand 2 is placed on the gonio base 1.
is fixed and protrudes vertically upward.

Inside the frame stand 2, a rotating frame 4 having a large-diameter circular ring O formed therein is rotatably provided. At the upper end of the frame stand 2, there is a power transmission means for transmitting the rotational motion of the pulse motor 5 to the rotating frame 4 to rotate the rotating frame 4 by an appropriate angle;
A power transmission means 6, for example comprising a worm and a worm wheel, is fixedly mounted.

An arm 7 is provided at the left end of the rotating frame 4 integrally with the rotating frame 4, a second slit member 11 is provided at the right end of the arm 7, and a second slit member 11 is provided at the left end of the arm 7. , xsg rotating plate 8 and crystal holder 9 are attached.

The Xllll rotary plate 8 and the crystal holder 9 are both
It can be rotated independently around the horizontal axis ω2, and can be rotated to an appropriate angular position by a rotational drive means (not shown), such as a pulse motor or manually, and a clamp is placed at the rotated position. In other words, the position can be fixed.

A first crystal 10 is fixedly attached to the tip of the crystal holder 9.

Mounting flange 8a provided at the lower end of the XB source rotary plate 8
An X-ray tube 12 is fixedly attached to the. This X-ray tube 12 is an X-ray tube of a well-known structure having a filament (not shown) that emits thermionic electrons and a target (anticathode 2, not shown) that generates X-rays by colliding with the filament. It is. A first slit member 13 is provided in the X-ray extraction window of the X-ray tube 12. X-ray tube 1
2, the point-shaped X&I is taken out from the point focus P.

A 2θ setting rail 14, which is an arcuate rail member, is fixedly provided on the right end of the rotating frame 4, which is integral with the arm 7, and an X-ray detector 15 is fixed on the rail.

In FIG. 1, an X
A Y child table 6 is fixedly arranged. As shown in FIG. 2, this XY child table 6 includes an X stage 18 that is moved in parallel in the X direction (parallel to the rotating frame 4) by an The Y-stage 20 is provided with a Y-axis pulse motor 19 and moves in parallel in the Y direction (direction perpendicular to the rotating frame).

A rectangular cylindrical case 21 is fixed on the Y stage 20, and a cylindrical sample stage support shaft 22 is supported by a bearing 36 fixed to the front surface of the case 21.

This sample stage support shaft 22 has its central axis, that is, the first
It is rotatably supported around a horizontal axis ωI.

Inside the case 21, a sign par 23, which is a plate-shaped bar, is fixedly attached to the rear end of the sample stage support shaft 22, and extends in one direction.

At one end of the case 21 is a pulse motor 24 for fine rotation drive.
is fixed downward. The worm 25 fixed to the output shaft of the pulse motor 24 has a worm gear 27 which is a component of a minute linear movement mechanism (so-called micrometer mechanism) 26 fixed to the right panel of the case 21.
are interlocking.

The minute linear movement mechanism 26 converts the rotational motion of the worm gear 27 into minute reciprocating linear motion of the actuator rod 28. The upper end of the signer 23 is in contact with the tip (left end) of the actuator rod 28 under constant pressure by a biasing means such as a spring (not shown).

When the fine rotation driving pulse motor 24 rotates, the actuator rond 28 moves straight due to the action of the fine linear movement mechanism 26, and the sign par 23 moves in the first horizontal axis ω accordingly.
It rotates slightly around 1. In accordance with this slight rotation of the signer 23, the sample stage support shaft 22 is also slightly moved up and down together with it.

A holding plate 29 is fixedly attached to the front end of the sample stand support shaft 22, and the sample stand 31 is swingably supported by support pieces 30, 30 provided on both sides of the holding plate 29. ing. A sample, for example 3 to 4 in diameter, is placed on the sample stage 31.
A single-crystal wafer 33 having a size of about an inch is simply placed thereon without being subjected to any fixing process such as adhesion or clamping. A sample tilting pulse motor 32 is provided on the bottom surface of the holding plate 29. This pulse motor 32
When rotates by an appropriate angle, the sample stage 31° and therefore the sample 33
tilts by a small angle.

As shown in FIG. 1, the sample stand support shaft 22 protruding from the case 21 and the sample stand 31 supported by it pass through the circular space 0 formed in the rotating frame 4 and are attached to the front side of the rotating frame 4. protrudes to.

With this configuration, point-shaped X-rays emitted from the X-ray focal point P of the X-ray tube 12 are irradiated to the first crystal 10 via the first slit member 13. At this time
The line is made monochromatic by being diffracted by the first crystal 10, and only a specific wavelength component 1, for example, the Ka line, is extracted.

The extracted monochromatic X-rays then enter the sample 33 via the slit member 11 in Figure ff12, where they are diffracted or scattered, and the intensity of these diffracted or scattered X-rays is detected by the Xi detector 15. Ru.

At that time, Signer 23. The sample 33 is rotated in an extremely small angular range around the first horizontal axis ωl, for example, for tens of seconds to hundreds of seconds, by the sample micro-rotation drive means constituted by the micro-linear movement mechanism 26 and the micro-rotation drive pulse motor 24. Extremely small step angles over the angular range,
For example, it rotates intermittently every 0.5 seconds. As a result, intensity information of the diffracted X-rays or scattered X-rays from the sample 33 at each angular position is obtained, and a so-called rocking curve as shown in FIG. 4 is obtained. From the X-ray intensity information for each incident XM angular position appearing on this rocking curve, 'fi!' for sample 33! The integrity, composition, etc. of the I membrane layer are evaluated. In Figure 4, the peak PI of the substrate crystal
This shows the state in which the beak P2 of the thin film was measured.

The rocking curve as described above is for one specific point on the sample 33. After completing the measurement for this particular point, in FIG.

The X-axis pulse motor 17 and/or the Y-axis pulse motor 19 are operated, and the entire case 21 is slightly translated in a horizontal plane. Due to this slight parallel movement, the sample 33 placed on the sample stage 31 is also moved in parallel.

In this way, the monochromatic X-ray sample 3 sent from the first crystal 10
3 can be moved to an arbitrary position different from the previous position, and a rocking curve (FIG. 4) for the different position can be obtained.

By changing the position of the sample 33 in the horizontal plane several times as described above, rocking curves at several different positions of the sample 33 can be obtained in an extremely short period of time.

This makes it possible to evaluate the sample 33, which has a particularly large area, with great accuracy.

The above rocking curve measurement is performed using X-ray source P, crystal I
This is done after the initial conditions of each device, such as 0, sample 33, and X-ray detection #; t15, are accurately set. Below, we will briefly touch on the initial setting operations.

Figure 3 is a plan view of the X-ray diffraction device viewed from the front side according to arrow III in Figure 1! IA is abbreviated. In the figure, first, the X-ray detector 15 is set at a diffraction angle 2θ=
Set the zero digit W (A). In addition, there is still a sample 33 on the sample stand 31 at the tip of the sample stand support shaft 22 (Fig. 1).
Do not leave it there.

In this state, the crystal holder 9 is rotated around the second horizontal axis ω2, and the X-ray detection @ 15 is set at the A position.
The crystal holder 9 is clamped to the X-ray source rotary plate 8 at the point where the X-ray intensity measured by is the maximum. As a result, the first crystal 10 is set at the optimum position, that is, the position where α-rays are diffracted.

Next, the X-ray source rotary plate 8 with the crystal holder 9 clamped thereon is slightly rotated together with the crystal holder 9 about the second horizontal axis ω2, and the diffracted X-rays from the first crystal 10 are transmitted to the sample 33.
Adjust precisely so that it passes through the center of the After that, sample stage 3
Sample 33 is placed on 1. At this time, it is preferable to provide a mechanism for raising and lowering the sample 33 in the vertical direction so that the measurement surface, ie, the upper surface, of the sample 33 is always kept at a constant position even when the thickness of the sample 33 varies. The elevating mechanism for this purpose may be a mechanism that raises and lowers the sample 33 with respect to the sample stage 31, or a mechanism that raises and lowers the entire sample stage 31 on which the sample 33 is placed.

Next, in FIG. 1, the frame rotation pulse motor 5
is started to rotate the rotating frame 4, and the position where the X-ray diffraction intensity in the sample 33 reaches its peak (θe in Fig. 4) is determined.
The angular position of the first crystal 10 is adjusted accordingly. At the same time,
Move the ray detector 15 along the 20 setting rail 14 and place it at a 2θ position where it can receive the diffracted X-rays from the sample 33.
Clamp the detector 15. The above completes the adjustment for finding the maximum peak (position 08) in the rocking curve (FIG. 4).

After the above operations have been performed, or at an appropriate timing while these operations are being performed, the tilting pulse motor 32 is operated to tilt the sample 33 by a small amount around the χ axis. This is to adjust the X-ray diffraction plane of the sample 33 to be parallel to the X-ray diffraction plane of the first crystal 10.

This is usually called "tilt adjustment."

With the above steps, the initial adjustment between the optical systems of the X-ray diffraction apparatus is completed, and a state is reached in which the above-described rocking curve measurement can be performed.

As already mentioned, the X-rays diffracted by the first crystal 10 are X-rays of a specific wavelength, for example, alpha rays.If we observe the alpha rays in detail, we can see the difference as shown in Figure 5. It is already known that the rays include α, rays, and α2 rays. When measuring rocking curves with a two-crystal X-ray diffraction device like this device, it is necessary to detect very precise changes in the diffraction X-ray intensity, and for this purpose it is necessary to
It is required that the X-rays incident on the first crystal 1 be precisely limited to those of a specific wavelength, and therefore it is preferable to remove the low-intensity α2 rays.
The following method is adopted regarding the position of the X-ray tube 12, particularly the point focus P, relative to zero.

As already explained, inside the X-ray tube 12, as shown in FIG. 6, thermionic electrons emitted from the filament 34 collide with the target 35, and X-rays are generated therefrom. Then, as shown in Figure 1, point-shaped X-cotton R is taken out, and the first crystal 10 (Figure 1) is irradiated with this. In this case, in a normal X-ray tube, target 3
The X-ray extraction angle θ from 5 is set to about θ = 6°, so the point-shaped X-ray R is not an exact square, but a 111
The surface becomes rectangular.

In this example, X$111111L when viewed from the direction shown in FIG. 3 is the short side (0.4#11 in the above case
1) so that the X-rays are incident on the first crystal 10.
The wire tube 12 is attached by setting its position. in this way,
Line l of X-rays incident on the first crystal 10 in the state shown in FIG.
The smaller the 1% IL, the narrower the line width of the Kα1 line and the line width of the α2 line in the α line after being diffracted by the first crystal 10. As a result, from the first crystal 10 to the second
Even if the distance Le to the slit member 11 is short, the progression of the α2 line is blocked by the second slit member 11 and α,
It is possible to ensure that only cotton passes through, that is, to separate and extract α1 rays. The above distance Ll! Being able to make it smaller means that the overall shape of the X-ray diffraction device can be made smaller.

Although the present invention has been described below with reference to one embodiment, the present invention is not limited to that embodiment.

For example, the specific structure of the sample micro-rotation driving means and other components may be any other structure.

The XY child table for parallelly moving the specimen micro-rotation driving means, as in the structure shown in Fig. 2, does not necessarily have to be
The structure is not limited to one that moves parallel to the Y axis direction, but a structure that moves in either one direction can also be used.

[Effects of the Invention] According to the present invention, by moving the sample in parallel in a horizontal plane using an XY child table, many positions within the sample can be selected as measurement positions, and rocking curves and other
It became possible to obtain line intensity curves. Therefore, compared to the conventional case where measurements were only made at one point, it has become possible to perform extremely accurate evaluations over the entire sample.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the whole of an embodiment of a sample horizontal double-crystal X-ray diffraction device according to the present invention, FIG. 2 is an IR view showing the main parts of the X-ray diffraction device, and FIG. A schematic diagram of the X-ray diffraction apparatus when viewed according to the arrow ■ in Figure 1,
Figure 4 is a graph showing an example of a rocking curve, which is the measurement result obtained using the above-mentioned X-ray diffraction device, and Figure 5 is
FIG. 6 is a spectrum diagram showing some of the wavelength components of X-rays generated from the ray tube, and is a diagram schematically showing how X-rays are generated within the X-ray tube. 4... Single rotation frame, 5... Pulse motor for rotating frame, 6... Power transmission means, 8... X-ray source rotating plate, 10... First crystal, 12... X-ray tube , 15... X-ray detector, 16... XY child table 18... X stage, 20... Y stage, 23... Sine bar, 24... Pulse motor for fine rotation drive, 25 ...Worm, 26
...Slight linear movement mechanism, 27...Worm gear.

Claims (3)

[Claims] (1) In an X-ray diffraction device that irradiates a sample with X-rays made monochromatic by the first crystal and measures the intensity of the X-rays diffracted by the sample, there is a sample stage on which the sample is placed horizontally; , a sample micro-rotation driving means for rotationally driving the sample stage over a predetermined angular range at minute step angles about a first horizontal axis; and a rotating frame provided around the sample stage at a distance from the sample stage. , frame rotation means for rotating the rotating frame around the first horizontal axis; and a rotating table provided on the rotating frame and rotatable about a second horizontal axis parallel to the first horizontal axis. , a first crystal that is provided on the rotary table and is rotatable about the second horizontal axis; an X-ray tube that is fixedly arranged on the rotary table and makes X-rays incident on the first crystal; The sample micro-rotation drive means has an X
An X-ray diffraction device characterized in that it is fixed on a Y table. (2) The X-ray diffraction apparatus according to claim 1, wherein the sample stage is tiltable so that parallelism with respect to the first crystal can be adjusted. (3) The X-ray diffraction apparatus according to claim 1, further comprising an elevating means for vertically elevating the sample mounting surface of the sample stage.