JP2732311B2 - X-ray topography equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an X-ray topography apparatus for observing lattice defects and lattice distortion in a single crystal.

Lattice defects included in single crystal wafers such as silicon and GaAs used as materials for semiconductor devices, or lattice defects generated during the manufacturing process of forming semiconductor devices are one of the causes of a decrease in device yield. Yes, and therefore controlling lattice defects has become an important issue.

As a method for observing the lattice defect, there are an etching method, an electron microscopy method, an X-ray topography and the like. Among them, X-ray topography is widely used for inspecting materials and improving processes, particularly in the semiconductor industry, because it has an advantage that a sample can be observed nondestructively.

[Prior Art] The above-mentioned X-ray topography is for directly observing a lattice defect or the like inside a crystal of a single crystal material. When this X-ray topography is roughly classified, primary X-rays generated from an X-ray source are directly incident on a sample crystal, and an image is formed by X-rays diffracted by the sample, such as a Lang method and a Berg Barrett method.
In a so-called single crystal method, the primary X-ray is made incident on the first crystal, the X-ray beam diffracted by the first crystal is used as the incident X-ray to the sample crystal, and an image is formed again by the X-ray diffracted by the sample crystal. And a two-crystal method.

In the one-crystal method, the degree of satisfying the diffraction condition changes due to a partial shift of the crystal orientation, and a black-and-white contrast corresponding to the lattice defect occurs due to a diffraction effect such as an extinction effect and a Borman effect. On the other hand, in the two-crystal method, the X-ray is diffracted twice by the first crystal and the second crystal (sample), so that the angle range satisfying the diffraction condition is several tens of minutes compared to the above-mentioned one-crystal method. From one to several hundredths. Therefore, according to the two-crystal method, it is possible to detect minute lattice defects and minute strains that cannot be detected by the one-crystal method.

However, the two-crystal method is applied to the observation of a sample crystal that is closer to perfection, and is very sensitive to distortion in the crystal, and therefore, if this is used for a crystal with low perfection, The area of the obtained image is a very limited area, and cannot be observed.

In X-ray topography, the above-described one-crystal method and two-crystal method are selectively used depending on the completeness of the crystal with respect to the type of defect, the magnitude of strain, and the like. Further, each of the above methods has a transmission arrangement in which X-rays are incident from the front surface of the sample and diffracted X-rays are extracted from the back surface, and a front surface in which X-rays are incident from the front surface of the sample and the diffracted X-rays are extracted from the front surface. Divided into reflective arrangements.

The transmission configuration is applied when observing a lattice defect image inside the crystal, whereas the surface reflection configuration is used to observe lattice defects only in the surface layer of the crystal.

Conventional X-ray topography apparatuses are based on a single-crystal method with a transmission arrangement typified by the Lang method, a single-crystal method with a surface reflection typified by the Berg Barrett method, and based on a two-crystal method with a surface reflection arrangement. And four types, such as those based on the two-crystal method of the transmission arrangement, existed individually as dedicated machines.

[Problem to be Solved by the Invention] As described above, conventionally, as an X-ray topography apparatus,
Since four types, such as the one-crystal method of the transmission configuration, the one-crystal method of the surface reflection, the two-crystal method of the surface reflection configuration, and the two-crystal method of the transmission configuration, were prepared separately, the operator could use all types. In order to perform the measurement based on the methods described above, all the X-ray topography apparatuses based on each method must be prepared, which is extremely uneconomical.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the conventional apparatus, and requires only a simple operation to perform the one-crystal method of the transmission arrangement, the one-crystal method of the surface reflection, and the two-crystal method of the surface reflection arrangement.
It is an object of the present invention to provide an X-ray topography apparatus capable of performing X-ray topography imaging based on all methods of a crystal method and a two-crystal method of a transmission arrangement.

Means for Solving the Problems To achieve the above object, the X-ray topography apparatus according to claim 1 is rotatable about one axis.
A rotating plate, a scanning stage arranged on the ω rotating plate, a first crystal support fixedly arranged on the scanning stage, and a first crystal support arranged on the scanning stage and arranged on the scanning stage And a second crystal support table arranged on the rotation base.

The scanning stage moves parallel to the ω rotating plate.

The first crystal support is fixed on the scanning stage, and moves with the scanning stage in an unfavorable manner with respect to the ω-rotating plate. In this case, the first crystal support moves so as to cross the rotation axis of the ω-rotating plate.

On the scanning stage, a rotation base is provided in addition to the first crystal support. However, this rotating base
Instead of being fixed to the scanning stage, it can be rotated about the first crystal support.

Since the second crystal support is provided on the rotation base, the second crystal support is consequently rotated around the first crystal support.

The sample to be measured is mounted on either the first crystal support or the second crystal support. That is, when performing the measurement based on the two-crystal method of the reflection arrangement and the transmission arrangement, the sample is mounted on the second crystal support, and the first crystal is mounted on the first crystal support. On the other hand, when performing the measurement based on the single crystal method, the sample is mounted on the first crystal support, and nothing is mounted on the second crystal support.

According to a second aspect of the present invention, a slit (first slit) is provided between the first crystal and the second crystal. This slit is held by a rotating plate (slit rotating plate) that rotates coaxially with the rotation axis of the ω rotating plate.

According to a third aspect of the present invention, there is provided a 2θ rotating plate capable of rotating coaxially with the ω rotating plate, and further comprising a tangential direction moving on the ω rotating plate with respect to the rotation direction of the ω rotating plate. A movable table is provided, and the X-ray detector is held by the movable table.

As the X-ray detector, a means for detecting and observing an X-ray image by an X-ray television camera, an X-ray image intensifier, or the like can be used, or other X-ray intensity detecting means such as a scintillation counter can be used. .

[Operation] In the invention of claim 1, the moving direction (A-A direction) of the scanning stage (8) can be freely changed by rotating the ω rotating plate (3). The second crystal support (12) is arranged on a rotating base (10),
By rotating the rotation base (10) about the first crystal support (11), the position of the second crystal support (12) can be freely changed.

Scanning movement direction of scanning stage (8) (A-A direction)
By appropriately changing the position and combination of the second crystal support (12) with respect to the first crystal support (11), the conditions of the optical system of the X-ray topography apparatus can be changed by the one crystal method of the transmission arrangement, the surface reflection, and the like. The method can be freely changed between at least four types of measurement methods, namely, the one-crystal method, the two-crystal method in the surface reflection configuration, and the two-crystal method in the transmission configuration.

In the invention of claim 2, the first slit (22) allows only the X-ray diffracted by the first crystal (16) to pass therethrough and blocks the other X-rays. This prevents extra X-rays other than diffracted X-rays, for example, primary X-rays, from going to the second crystal (17). Since the first slit is held by the slit rotation plate (25) that can rotate coaxially with the ω rotation plate, the first slit has an integrity with the first crystal (16) supported on the first crystal support base (11). Is ensured and therefore the positioning of the first crystal is very simple.

According to the third aspect of the present invention, the 2θ rotating plate (20) can rotate coaxially with the ω rotating plate (3), and the moving table (27) is tangential to the rotation direction of the 2θ rotating plate. It can move in the direction (DD direction). The X-ray detector (28) is used when adjusting the angular position of each crystal, the position of each slit, and the like.
Since this X-ray detector is provided on the above-mentioned movable table, it is possible to freely combine 2θ rotation and tangential movement, thereby making the above adjustment in the above four types of X-ray topography. When performing, the X-ray detector can be easily matched with the direction of the diffracted X-ray.

FIG. 1 shows an embodiment of an X-ray topography apparatus according to the present invention. In FIG. 1, a main body base 2 is placed on a base frame 1. As shown in FIG. 2, the main body base 2 is provided with an ω-rotating plate 3 at an upper portion thereof. The ω rotating plate 3 is provided on the main body base 2 so as to be rotatable about one axis (perpendicular in the embodiment) ω 1, and is clamped at a predetermined position during normal measurement. I have. Also,
By loosening the clamp, it can be manually rotated by an appropriate angle, for example, 0 to 150 °.

As shown in FIG. 3, a sine bar 4 is attached to the rotating shaft 3a of the ω rotating plate 3, and a clamp knob 31 is provided at the left end of the sine bar 4. On the other hand, at the right end of the sine bar 4, the pulse motor 5, the gear 32
a, 32b, a micrometer head 33 and a pressing spring 34 are arranged. When the pulse motor 5 is rotated with the clamp knob 31 tightened, the rotation is transmitted to the micrometer head 33 via the gears 32a and 32b, and the micrometer head is rotated. At this time, the end face of the micrometer spindle is rotated. The sign bar 4 is pressed to rotate the ω-rotating plate 3. Thereby, the ω rotating plate 3 can be slightly rotated. The pressing spring 34 functions to press the sign bar 4 against the micrometer head 33.

Returning to FIG. 1, a stage block 6 is provided on the ω rotating plate 3. The stage block 6 has a base 7 fixed on the ω-rotating plate 3 and a scanning stage 8 disposed on the base 7. The scanning stage 8 is driven by a motor 9 fixed to the base 7 and moves while sliding on the base 7. As a result, as shown by an arrow AA in FIG.
Can move in parallel with the ω-rotating plate 3.

On the scanning stage 8, a rotation base 10 and a first crystal support 11 are provided. In this case, the first crystal support 11 is fixed to the scanning stage 8, while the rotation base 10 can be rotated around the first crystal support 11. The center of the first crystal support 11 is aligned with the axis ω1, which is the center of rotation of the ω rotating plate 3, and when the scanning stage 8 moves in the direction of arrow AA, the first crystal support 11 11 moves so as to cross the axis ω1.

The rotation base 10 can be manually and rotationally moved around the first crystal support 11 in an appropriate range, for example, within a range of ± 30 °. Further, it can be clamped, that is, fixedly held at an appropriate position described later.

As shown in FIG. 4, the rotation base 10 has a substantially triangular shape, and the first crystal support 11 is provided at the left end thereof. A second crystal support 12 is provided at the right end of the rotary base 10, and a motor 13 is provided at the upper end thereof.

The second crystal support 12 has an axis ω 2 with respect to the rotation base 10.
(See FIG. 2). In this case, the second crystal support 12 has a so-called two-stage coaxial structure, and a sine bar 14 is connected to the first stage, and a worm and a worm wheel are mounted to the other first stage. The pulse motor 15 is connected via the power supply. The sign bar 14 is moved by the motor 13 via a worm and a worm wheel. With the above configuration, the second crystal support base is driven by the pulse motor 15.
12 can be roughly rotated about the axis ω2.
Further, the second crystal support base 12 can be slightly rotated by the sine bar 14 driven by the motor 13.

In the apparatus according to this embodiment, as will be described later, at least four types of one crystal method of the transmission arrangement, one crystal method of the surface reflection, two crystal methods of the surface reflection arrangement, and two crystal methods of the transmission arrangement are used in one apparatus. You can shoot. When imaging by the two-crystal method, the first crystal 16 is placed on the first crystal support 11.
Is set, while the sample 17 is set on the second crystal support 12. On the other hand, when performing the measurement by the one-crystal method, the sample 17 is set on the first crystal support 11 and nothing is set on the second crystal support 12.

In FIG. 4, a film holder 18 is mounted on the right side of both the first crystal support 11 and the second crystal support 12, and an image is selectively recorded on one of these film holders. A photographic dry plate as a body, that is, a film 19 is set. These film holders 18
Are the first crystal support 11 and the second crystal support, respectively.
The angle position with respect to 12 can be freely changed.

Returning to FIG. 1, a slit rotary plate 25 which is a rotary plate capable of rotating coaxially with the ω rotary plate is provided below the ω rotary plate 3. As shown in FIG. 5, a bracket 29 is formed on the slit rotating plate 25, and a column 23 and a beam 21 are disposed on the bracket. A first slit 22 is rotatably supported at the tip of the beam 21 and is suspended below. The support 23 can move in the direction of arrow CC along the guide protrusion 30 provided on the bracket 29, while the beam 21 moves in the direction of arrow BB with respect to the support 23. You can do it.

According to the above configuration, the first slit 22 can be set at an arbitrary desired position. This first slit 22
Usually, as shown in FIG. 1, the right side of a first crystal 16 (a sample 17 in some cases) supported by a first crystal support 11
That is, the film holder 18 is arranged on the side where the film holder 18 is located.

In FIG. 1, below the slit rotary plate 25, there is another rotary plate 2 which can rotate coaxially with the ω rotary plate 3.
θ rotating plate 20 is provided. The 2θ rotating plate 20 includes:
As shown in FIG. 6, a moving table 27 is provided which moves linearly in a tangential direction (DD direction) with respect to the rotation direction of the 2θ rotating plate 20. An X-ray detector 28 is fixed to the movable table, and a beam 26 is attached to an upper end thereof.
The beam 26 can move in the direction of arrow EE with respect to the moving table 27, that is, in the direction toward or away from the center of the ω-rotating plate 3. At the tip of the beam 26, a second slit 24 is rotatably suspended.

This second slit 24 is usually provided as shown in FIG.
The second crystal (sample) 17 is arranged on the right side of the set position. As will be described later, the second slit 24 is necessary only in the case of the two-crystal method in the transmissive arrangement, and is not necessary for the other three types of imaging. Has become.

In FIG. 1, X-rays generated from an X-ray generation source (not shown) are guided to a generation unit slit 36 through an X-ray introduction tube 35. The width and height of the X-ray are limited by the slit 36, and the first crystal 16 or the sample 17 on the ω1 axis is restricted.
And diffracted here.

The X-ray diffracted by the first crystal 16 or the like then passes through the first slit 22. At this time, primary X-rays other than diffracted X-rays are blocked. As described above, the first slit 22 is supported by the slit rotary plate 25 that can rotate coaxially with the ω rotary plate 3 and, as shown in FIG. 5, in two directions orthogonal to each other (the BB direction and the CC direction). Direction), it can be easily placed at the desired position.

As will be described later in detail, the X-ray diffracted by the first crystal 16 or the like is thereafter incident on the film 19 attached to the first crystal support 11 in the case of the one-crystal method, while it is in the case of the two-crystal method. It is led to the second crystal (sample) 17. In this case, the X-rays are diffracted again by the second crystal (sample) 17 and thereafter, the second crystal support 12
Is incident on the film 19 attached to. At this time, the second slit 24 arranged between the second crystal (sample) 17 and the film 19 allows only the X-ray diffracted by the second crystal (sample) 17 to pass toward the film 19.

The second slit 24 is supported by the 2θ rotating plate 20 which can rotate coaxially with the ω rotating plate 3 and has two directions orthogonal to each other (the DD direction and the DD direction), as already described with reference to FIG. (E-E direction), so that it can be easily arranged at the target position.

The X-ray detector 28 mounted on the moving table 27 is adjusted so as to coincide with the direction of the diffracted X-ray at the stage of adjusting the angular position and the like of each crystal.
By the rotation of 20 and the movement in the tangential direction (DD direction), the position can be easily adjusted.

As the X-ray detector 28, one that can detect diffracted X-rays as an X-ray image, such as an X-ray television camera or an X-ray image intensifier, or an X-ray intensity detecting means, such as a scintillation counter, is used. be able to.

Since the X-ray topography apparatus according to the present embodiment has the above-described configuration, a simple operation as described below is performed, and if desired, a two-crystal method of a reflection arrangement can be used.
At least four types of measurement can be performed: a two-crystal method of transmission arrangement and a one-crystal method of transmission and surface reflection.

This method is a method called rung, and the optical system is arranged as shown in FIG.

First, the sample 17 is mounted on the first crystal support 11 in parallel with the scanning direction (A-A direction) of the scanning stage 8. The ω rotating plate 3 is roughly set at a predetermined angle and fixed (clamped). The X-ray detector 28 sets the diffraction angle (2θ) corresponding to the lattice plane of interest. This is 2θ
This is realized by setting the rotating plate 20 to the diffraction angle and not performing the movement in the tangential direction (DD direction).

Next, the X-ray detector 28 is activated to generate X-rays. Then, the sample is displayed by the sign bar 4 (FIG. 3).
17 is slightly rotated about the ω1 axis, and the ω angle is set at a position where the X-ray detector 28 shows the highest intensity. Actually, in addition to the adjustment of the ω angle, the orientation adjustment by in-plane rotation and excessive rotation of the crystal is required.

Next, the position of the first slit 22 is adjusted. That is, while monitoring the X-ray intensity with the X-ray detector 28, only the diffracted X-rays are passed and unnecessary X-rays such as direct X-rays are shielded.

Then, the X-ray detection film 19 is placed on the first crystal support 11.
And exposes X-rays there. During this exposure, the X-ray topograph having a large area can be obtained by reciprocating the scanning stage 8 in the AA direction at a constant speed.

Single Crystal Method of Surface Reflection Arrangement In this method, the optical system is arranged at the position shown in FIG.

The big difference from the case of the transmission arrangement of FIG.
This means that the X-ray incidence angle with respect to 17 is small. This is because in the case of surface reflection, X-rays are often diffracted on a lattice plane appropriately inclined with respect to the sample surface. In order to achieve such a small incident angle of X-rays, the rotation angle of the ω-rotating plate 3 is largely changed as compared with the case of FIG. Also, accordingly, the position of the X-ray detector 28,
Therefore, the rotation angle of the 2θ rotating plate 20 is also changed.

In this method, the sample 17 is mounted on the first crystal support 11 in parallel with the scanning direction (A-A direction) of the scanning stage 8, fine adjustment of the ω angle of the sample 17 by the X-ray detector 28, The adjustment of the position of the slit 22 and the like, and the fact that a wide area X-ray topograph is obtained by the scanning movement of the scanning stage 8 in the AA direction are the same as those in the case of the transmissive arrangement in FIG.

In the case of the two single crystal methods described above, since no special crystal is arranged on the second crystal support table 12, the illustration of the portion is omitted in FIGS. 7 and 8.

Two-crystal method of transmission arrangement The arrangement of the optical system in this method is shown in FIG.

First, the first crystal 16 is a single crystal method in a transmission arrangement (FIG. 7).
It is mounted on the first crystal support 11 in the same procedure as in the above case. Next, the rotating base 10 is rotated in the direction of the X-ray diffracted by the first crystal 16, and the second crystal (sample) 17 is mounted on the second crystal support 12. Next, the 2θ rotating plate 20 is returned to the position of the angular position 0 ° (reference position), and the X-ray detector 28 is moved in the tangential direction (DD direction) to make it coincide with the direction of the diffracted X-ray.

Next, the second crystal (sample) 17 is roughly and finely rotated about the ω2 axis to adjust the ω angle of the second crystal (sample) 17. The orientation is also adjusted, and the second crystal (sample) 17 is set at an optimum position with respect to the diffracted X-ray. After that, the second slit 24 is arranged at a predetermined position, the film 19 is attached to the second crystal support 12, and the X-ray is exposed to the film 19. Also in this case, the scanning stage 8
, A wide area X-ray topograph can be obtained.

Surface Reflection Two Crystal Method The arrangement of the optics in this method is shown in FIG.

In this method, the first crystal 16 is mounted on the first crystal support 11 in the same procedure as in the single crystal method of surface reflection (FIG. 8). Further, rotation of the rotation base 10, movement of the X-ray detector 28 in the tangential direction (DD direction), adjustment of the ω angle of the second crystal (sample) 17, and the like are performed, and these are placed at the positions shown in the figure. . Although the arrangement position is different, the rotating base 10
The operation procedure itself is the same as in the case of the two-crystal method of the transmission arrangement in FIG.

In the case of the two-crystal method of surface reflection, as shown, the second slit 24 is not used.

As described above, according to the present embodiment, measurement based on at least four different methods can be performed by one device, and it is not necessary to prepare dedicated devices for each method.

Although the present invention has been described with reference to one embodiment, the present invention is not limited to the embodiment and can be variously modified.

For example, the scanning stage 8 shown in FIGS. 7 to 10,
The arrangement positions of the rotation base 10 and the like are merely examples, and other appropriate arrangement positions may be used as necessary.

The shape and structure of the scanning stage 8, the rotating base 10, and the like can be arbitrary other than those in the embodiment.

As an image recording body for recording an X-ray diffracted by the sample 17 as an image, a so-called stimulable phosphor can be used in addition to the film 19 in the embodiment. In this case, an energy latent image corresponding to the diffracted X-ray is formed inside the stimulable phosphor.

In the above-described embodiment, the rough rotation of the ω-rotating plate 3 has been described as being manually performed. Alternatively, the coarse rotation may be automatically performed using a driving unit such as a motor.

According to the first aspect of the present invention, the first crystal support (11) and the second crystal support (1) are provided directly on the scanning stage (8).
Instead of mounting 2), a rotating base (10) is interposed on the scanning stage (8), and the rotating base (1
0), the first crystal support (11) and the second crystal support (12) are arranged, so that the relative positions of the first crystal (16) and the second crystal (sample: 17) can be adjusted. As a result, a single crystal method of the transmission arrangement, a single crystal method of the surface reflection, a two crystal method of the surface reflection device, which had to be conventionally performed by an individual dedicated machine, In addition, topography can be photographed by one apparatus by at least four kinds of two crystal methods in a transmission arrangement.

According to the second aspect of the present invention, the first slit (22) with respect to the first crystal (16) can be obtained even when the arrangement positions of the scanning stage (8), the rotating base (10) and the like are changed between the above methods. Can be set very easily.

According to the third aspect of the present invention, even when the arrangement positions of the scanning stage (8), the rotating base (10), and the like are changed between the above methods, the X-ray detector (28) can very easily diffract X-rays. Can be matched to the direction of the line, and the second slit (2
The position 4) with respect to the X-ray detector (28) can also be easily set.

[Brief description of the drawings]

FIG. 1 is a side view of an embodiment of the X-ray topography apparatus according to the present invention, FIG. 2 is a perspective view showing a main part of FIG. 1, and FIG. 3 is along the line III-III in FIG. FIG. 4 is a plan view showing an embodiment of the rotating base, FIG. 5 is a perspective view showing another main part of FIG. 1, and FIG. 6 shows still another main part of FIG. 7 to 10 are plan views showing examples of the arrangement of the optical system in different X-ray imaging methods. 17 ... sample, 19 ... film, ω1 ... axis, 3 ... ω rotating plate, 8 ... scanning stage, 16 ... first crystal, 11 ... first crystal support base, 10 ... rotating base, 17 second crystal (sample), 12 second crystal support 25 25 slit rotating plate, 22 first slit, 20 2θ rotating plate, 27 movable stage, 28 X-ray Detector, 24 ... Second slit

Claims (3)

(57) [Claims] An X-ray topography apparatus for irradiating a single-crystal sample with X-rays and recording an X-ray image diffracted by the sample on an image recording body to create an X-ray topograph, wherein one axis is centered. A ω-rotating plate that is rotatable as, a scanning stage disposed on the ω-rotating plate and moving in parallel to the ω-rotating plate, and fixedly disposed on the scanning stage, A first crystal support on which the first crystal is mounted, the first crystal support being mounted on the scan stage, wherein the first crystal is mounted on the first crystal support when the scanning stage moves; A rotation base that can rotate as a first crystal support, and a second crystal support that is disposed on the rotation base at a distance from the first crystal support and on which a second crystal is mounted. The first crystal support or the second crystal An X-ray topography apparatus characterized in that a sample is placed on a support and X-ray topography of the sample is performed. 2. A slit rotating plate capable of rotating coaxially with a rotation axis of the ω rotating plate, and a slit rotating plate held by the slit rotating plate and disposed between the first crystal and the second crystal. The first to pass the X-ray beam diffracted by the crystal and block other X-rays
The X-ray topography apparatus according to claim 1, further comprising: a slit. 3. A 2θ rotating plate capable of rotating coaxially with the ω rotating plate, a movable table disposed on the 2θ rotating plate and movable in a tangential direction to the rotation of the 2θ rotating plate, and An X-ray detector disposed on the moving table, disposed between the second crystal and the image recording medium, and passing an X-ray beam diffracted by the second crystal to allow other X-rays to pass therethrough. The X-ray topography apparatus according to claim 1, further comprising a second slit that blocks a line.