JP2905659B2 - X-ray apparatus and evaluation analysis method using the apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal utilizing X-rays,
The present invention relates to an X-ray apparatus for three-dimensional, non-destructive, non-contact evaluation analysis of various single crystal materials such as semiconductors and dielectrics, multilayer films, devices, and the like, and a method for evaluating and analyzing a sample using the apparatus.

[0002]

2. Description of the Related Art At present, there is a method using X-rays as a method for non-destructively and non-contactly evaluating and analyzing metals, semiconductors and the like in atomic order. For example, there are a bonding method as a method for precisely measuring the lattice constant, a two-crystal method and a four-crystal method as a method for evaluating crystal integrity, and a fluorescent X-ray analysis method as a composition analysis method.

The evaluation analysis information obtained by the above-mentioned method using X-rays is the average information of all the regions where X-rays have entered. That is, in the conventional X-ray analysis method, the penetration depth of the X-ray is 10 μm, reflecting the weak interaction between the X-ray and the substance.
Because of the above, only an average analysis result at a depth of 10 μm can be obtained. Therefore, in order to obtain information in the depth direction of the sample, measurement may be performed several times using several reflections at different penetration depths of the X-ray, or a synchro- nous which is a continuous wavelength light source may be used as the X-ray source. Take a method such as using tron radiation.

On the other hand, as a method other than X-rays, an evaluation and analysis method of observing a minute region in an atomic order by an electron microscope or the like is also frequently used. However, the preparation of the sample is complicated in the observation method, and in order to observe in the depth direction, the cross section of the sample must be cut to produce a flaky sample of 1,000 angstroms or less. The scanning tunneling microscope can observe the surface at the atomic level in a non-destructive manner, but cannot obtain any information in the depth direction of the sample.

A secondary ion mass evaluation analyzer (S) is widely used as a trace element evaluation analyzer.
IMS) and Auger electron spectroscopy (AES), both of which are methods for performing evaluation analysis in the depth direction while scraping the sample surface with ions.

[0006]

In the above-mentioned conventional evaluation analysis method, particularly, the method using X-rays, it is difficult to evaluate and analyze the distribution in the depth direction, and the problem is that it is complicated.

[0007] The penetration depth of X-rays is determined by the integrity of the crystal, the path length from when the X-rays are incident, diffracted and emitted, and the amount of X-rays absorbed by the substance. The absorption coefficient of a substance increases with low-energy X-rays, and also increases on the high energy side of the absorption edge of the element constituting the substance. The path length can be increased by reducing the incident angle of the X-rays on the sample surface or the exit angle from the crystal surface. Therefore, by selecting the optimal X-ray reflection and wavelength for the substance of the target sample for evaluation analysis, it is possible to obtain evaluation analysis information from the information on the outermost surface under the condition of total reflection to a deep region of 10 μm or more. It is.

However, for example, the semiconductor material G
To evaluate and analyze aAs in the depth direction (200), (4)
It was necessary to perform several reflection measurements with different X-ray penetration depths, such as (00), (600), and (800) reflections. However, according to this method, only the evaluation analysis results of the discrete penetration depth can be obtained, and the measurement conditions are slightly different, so that setting of the conditions is time-consuming and inefficient. It is.

At present, it is possible to select an appropriate wavelength for evaluation analysis only when synchrotron radiation, which is a white intense light source, is used as an X-ray source. This is not possible with a sealed or rotating anti-cathode X-ray source. In the method of selecting an appropriate wavelength using synchrotron radiation, a huge facility called synchrotron radiation must be used, which is not useful as an industrial evaluation method.

Further, a major problem of the conventional evaluation analysis method other than the use of X-rays is the destructive inspection. Therefore, when evaluating the crystallinity and chemical composition of the semiconductor device structure once manufactured, it is necessary to evaluate the structure other than the surface. Have all involved complicated operations such as etching and cross-sectional sample preparation. In other words, for actual material evaluation and device evaluation, destructive inspection not only may impair the original properties, but also incorporates rapid evaluation during various manufacturing processes and is extremely important for device fabrication. Inefficient and undesirable.

In view of the above, the present invention provides an X-ray apparatus capable of rapidly obtaining a non-destructive inspection, a non-contact inspection, and an evaluation analysis profile in the depth direction, and an evaluation analysis method using the X-ray apparatus. The purpose is to provide.

[0012]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has an X-ray generator, at least one X-ray collector made of a single crystal material, and
A sample stage having an orthogonal tilting mechanism in two directions, a horizontal moving mechanism in three directions connected to the tilting mechanism, and an in-plane rotation mechanism connected to the horizontal shifting mechanism and at least a sample outside the tilting mechanism; Further, a goniometer provided with a three-way scanning rotation mechanism to which the sample stage arm is attached, a counting system provided with at least a detector and a counter for detecting X-rays, and a control system for performing control, measurement, and analysis. An X-ray apparatus including a computer is characterized.

According to a second aspect of the present invention, in the above-described X-ray apparatus, the counting system includes a storage phosphor sheet and a device for reading a signal from the storage phosphor sheet to measure the diffraction X-ray. It is characterized by an X-ray diffractometer for performing.

According to a third aspect of the present invention, in the X-ray apparatus as described above, the counting system includes an ultra-sensitive X-ray camera and an image processing apparatus for analyzing a topographic image from the X-ray camera, It is characterized by an X-ray device that measures the temperature.

According to a fourth aspect of the present invention, there is provided the X-ray apparatus as described above, wherein the counting system includes a semiconductor detector and an energy analyzer and measures a fluorescent X-ray. In particular, preferably in the apparatus of the present invention 10 ^- it is characterized by using in ^{1 0} Torr in the vacuum ^{- 2-10.}

According to a further aspect of the present invention, there is provided an evaluation and analysis method using the X-ray apparatus according to any one of the first to fourth aspects of the present invention. Using a three-way horizontal movement mechanism connected to the tilt mechanism, the sample is set so that the normal vector of the crystal lattice plane and the rotation axis direction of the in-plane rotation mechanism coincide with each other. Using a sample in-plane rotation mechanism connected to the outside of the tilt mechanism, the sample in-plane rotation table is continuously rotated in-plane while satisfying the diffraction condition for the sample, and the obtained diffracted X-rays or fluorescent X-rays are obtained. A feature is also an evaluation and analysis method for diffracted X-rays or fluorescent X-rays, which is characterized by continuously measuring a line with a counting system.

[0017]

According to the present invention, the diffraction analysis sample which is not parallel to the crystal surface, that is, the asymmetric reflection surface is positively used to rotate the evaluation analysis sample in plane while satisfying the diffraction conditions, thereby obtaining the X-ray incidence angle and emission angle. By continuously changing the angle, the penetration depth of the X-ray is continuously changed.

That is, according to the X-ray apparatus of the present invention, a tilting mechanism is first provided in the two axial directions orthogonal to the evaluation analysis sample, and the lattice plane is adjusted. That is, by making the normal vector of the lattice plane coincide with the rotation axis of the in-plane rotation mechanism (table), even if the sample body is subsequently rotated in-plane,
The sample can be rotated in the plane while satisfying the asymmetric reflection diffraction condition, and the incident angle (or the outgoing angle) with the crystal surface can be continuously changed. In other words, by setting the tilting mechanism in the two orthogonal directions perpendicular to the evaluation analysis sample, the penetration depth of the X-ray can be continuously changed with extremely high accuracy by setting the tilting mechanism in a direction closer to the rotary table in the sample plane. It is.

Incidentally, in the configuration of the X-ray apparatus according to the present invention,
In a sample stage having a tilting mechanism, a horizontal moving mechanism, and a sample table rotating table, at least two axes of the three-axis horizontal moving mechanism are installed at any position before and after the tilt mechanism and the sample table rotating table. There is no effect on the mechanism.

The detection signals according to the present invention include diffraction X-rays and fluorescent X-rays. Usually, a scintillation counter is often used as a signal detector for diffracted X-rays.
Detection up to about 0 ⁵ cps (count per second) can be performed extremely accurately. Therefore, by measuring the diffraction intensity two-dimensionally while continuously changing the penetration depth of the X-rays by the above method, and performing differential measurement with a computer, the depth direction can be measured with a resolution of about 100 °. . That is, it is possible to observe the distribution of the crystallinity of any substance, multilayer film, device, or the like at substantially the above resolution in a three-dimensional, nondestructive, noncontact manner.

If a high-sensitivity X-ray camera and a high-resolution film are used as detectors, three-dimensional observation of microstructure such as defects by X-ray topographic evaluation analysis can be performed in the same manner.

Furthermore, light elements at normal pressure is difficult to measure the atmospheric scattering even 10 ^{- 2} ~10 ^{- 1 0} Tor
By using a semiconductor detector as a detector and measuring fluorescent X-rays in a device having a high vacuum of r, it is possible to accurately evaluate and analyze the two-dimensional composition distribution and the like for the evaluation analysis of a trace amount of light elements. .

[0023]

【Example】

<Embodiment 1> FIG. 1 is a schematic view of an X-ray apparatus for carrying out the present invention, and FIG. 2 is a view for explaining a mechanism of a special goniometer capable of rotating a sample in a plane while satisfying a diffraction condition of asymmetric reflection. FIG. The mechanism of the X-ray apparatus of the present invention and the first embodiment will be described below with reference to FIGS. X-rays emitted from the X-ray generator 1 are converted into an X-ray collector 2
After narrowing down to an X-ray beam with good parallelism and a small wavelength width using (for example, composed of 1 to 4 germanium single crystals), the X-ray beam is incident on the surface of the sample 3 to be measured.
The X-ray collector here is composed of Si, GaAs, LiF,
Any material can be used as long as a high-quality single crystal such as PC (pyrolytic carbon) can be obtained.

As shown in FIG. 2, the measurement sample 3 has independent horizontal movement mechanisms in three axis directions, that is, an X axis, a Y axis, and a Z axis.
Shaft horizontal movement mechanism (numbers 4, 5, and 6 in the figure), first and second
Is mounted on a goniometer having a two-way tilt mechanism (numbers 7 and 8 in the figure), and the goniometer is mounted on a Ψ-sample in-plane rotary table 9 having a horizontal axis. Here, the tilting mechanism 7 and the tilting mechanism 8 are respectively installed in orthogonal directions, and are installed at a position closer to the measurement sample than the Ψ-sample in-plane rotation table 9. By setting the positional relationship between the tilt mechanism and the in-plane rotation table as in the apparatus of the present invention, it is possible to rotate the sample in-plane while satisfying the asymmetric reflection diffraction condition. Here, one of the two-way tilt mechanism and the three-axis horizontal movement mechanism is a tilt mechanism in the XZ plane, and the other is a tilt mechanism in the YZ plane.

Here, the X-axis, Y-axis, and Z-axis horizontal movement mechanisms 4, 5, and 6 are mechanisms for setting the sample position with respect to the incident X-ray flux, and particularly the X-axis 4 and Y-axis horizontal movement mechanisms. Mechanism 5
It may be mounted at any position before or after the lifting mechanisms 7 and 8 or the rotary table 9 in the sample plane. However, it is preferable that the Z-axis horizontal moving mechanism 6 is mounted on the rear side of the rotary table 9 with respect to the sample.

The arm of the goniometer is mounted on three independent ω-scanning rotation axes 10, θ-scanning rotation axes 11, and 2θ-scanning rotation axes 12, each of which has a vertical axis as a whole. The θ-scanning rotation axis 11 is an axis for rotating the sample horizontally with respect to the X-ray generator, and the ω-scanning rotation axis 10 is an axis for performing fine adjustment of the θ-scanning rotation axis 11. Yes, the 2θ-scanning rotation axis 12
Is an axis for setting the detector 13.

The goniometer can be automatically set to the plane orientation and arrangement given by the computer control. At this time, even if the Ψ-in-plane rotary table 9 is rotated, the diffraction condition of the asymmetric reflection is not changed. Can be filled. The three ω, θ, 2θ-scanning rotation axes can be scanned in any combination when measuring the diffraction intensity profile.

Then, the diffracted X-ray or fluorescent X-ray signal is measured by the detector 13 selected by a detection method of a type corresponding to the purpose of evaluation and analysis. Furthermore, a counting system including a wave height analyzer, a counter, and the like, and a lock-in amplifier, an energy analyzer, and the like for performing high-precision evaluation analysis are used to perform signal processing to obtain an evaluation analysis result.

In the first embodiment, GaAs was used as a measurement sample.
Using a ZnSe film formed on a substrate, using a scintillation detector usually used as the detector,
The diffraction X-ray signal was measured, and evaluation analysis was performed. The results are shown in FIGS. 3 (a) and 3 (b). In FIG. 3, the horizontal axis represents the distance in the depth direction from the sample crystal surface, the vertical axis represents the crystal mixture ratio in FIG. 3 (a), and X in FIG. 3 (b).
The line half width is shown. The results show that the sample has no difference in the mixed crystal ratio in the depth direction, and has good and uniform crystallinity.

That is, according to the conventional X-ray apparatus, it was impossible to continuously evaluate and analyze the mixed crystal ratio and crystallinity in the depth direction of the sample, or a large apparatus such as synchrotron radiation was used. It took a lot of effort to use it,
ADVANTAGE OF THE INVENTION According to the X-ray apparatus and evaluation analysis method of this invention, it became possible to perform evaluation analysis in the depth direction precisely and easily.

<Embodiment 2> A second embodiment using an X-ray apparatus having substantially the same configuration as that of Embodiment 1 except that a storage phosphor sheet is used as a detector and a reading device is provided will be described.

The storage phosphor sheet is also rotated in synchronization with the Ψ rotation of the in-plane rotation table 9 and the ω rotation of the scanning rotation shaft 10. The diffraction X-ray intensity data recorded on the sheet is measured by a reading device using a laser beam. With the storage phosphor sheet, information can be obtained with a plane resolution of 100 × 100 μm ² , so three-dimensional measurement is possible by combining this with depth measurement by Ψ rotation of the in-plane rotation table. Becomes

In the present example, a sample of a ZnCdSSe film formed on a GaAs substrate was used as a measurement sample, and diffraction X-ray signals were measured by the above-mentioned apparatus, and evaluation analysis was performed. The results are shown in FIG. Show. In this embodiment, the diffraction X-rays are measured while continuously slicing the crystal plane in the depth direction from the crystal surface of the sample toward the substrate, and FIG. 4 shows the X-rays of the crystal plane at three places. The half-value width distribution is shown by a five-step black and white color tone display. As can be seen from FIG. 4, ZnCdS
In the Se / GaAs sample, the crystallinity changes in the depth direction, and it can be seen that the crystallinity particularly decreases at the interface.

In the present apparatus, since the accuracy of the X-ray intensity becomes about 0.1% by the correction of the counting process, the resolution in the depth direction is 10 ° for a thin film having a thickness of 1 μm. That is, 100 × 1
Non-destructive, non-contact three-dimensional measurement of a semiconductor element was enabled with a mesh of 00 × 0.001 μm ³ . In this embodiment, a two-dimensional position-sensitive proportional counter can be used as the detector.

<Third Embodiment> A third embodiment of an X-ray apparatus having substantially the same configuration as that of the first embodiment except that an ultra-sensitive X-ray television camera is used as a detector and an image processing apparatus is provided.
An example will be described. In this embodiment, a change in the depth of the topographic image can be observed.

In this example, a ZnS _0.3 Se _0.7 film sample formed on a GaAs substrate was used as a measurement sample, and diffraction X-ray signals were measured by the above-mentioned apparatus, and evaluation analysis was performed. It is shown in FIG. FIG. 5A shows G before the episode.
FIG. 5 shows a topographic image of an aAs2 inch wafer, and FIG.
(B) shows a topographic image of the surface of ZnS _0.3 Se _0.7 after the end of the epitaxy, and FIG. 5 (c) shows ZnS _0.3 after the end of the epitaxy.
Information between the interface of Se _0.7 surface and GaAs and ZnS _0.3 Se _0.7 indicates topographic image of the mixed measurement results.

Using this apparatus, the in-plane rotating table 9
As a result of performing topographic observations while continuously changing the Ψ-rotation, misfit dislocations and stacking faults were observed near the interface, and dislocation loops presumably introduced from the surface were observed near the surface. Plane resolution is about 10 × 10μm
^{Was 2} .

[0038] <Example 4> the space of the measuring sample installation 10 ^{-
2-10 -} keeping the ³ Torr high vacuum, the detector except for the use of semiconductor detectors is described a fourth embodiment according to the X-ray apparatus having substantially the same configuration as in Example 1. In this embodiment, fluorescent X-rays can be measured.

By using the goniometer according to the present invention and performing the Ψ-rotation of the in-plane rotating table 9 in the same manner as in the embodiment, the penetration depth of X-rays is 10 μm from the total reflection.
Vary to the extent. That is, the excited fluorescent X-rays also change, and the depth-resolved analysis of the constituent elements can be performed.

When the impurity evaluation analysis of the Si substrate was performed using this apparatus, it was found that only the outermost surface was 10 ⁹ atoms / s.
Fe, Ni, Cu, Zn, etc. in cm ² were detected.

[0041]

According to the present invention, various materials such as metals, semiconductors, and insulators, and elements having a minute and complicated structure composed of them can be non-destructively, non-contacted, and tertiary including the depth direction. It has become possible to make an original evaluation.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an X-ray apparatus for implementing the present invention.

FIG. 2 is a schematic view of a special goniometer capable of rotating a sample in a plane while satisfying a diffraction condition of asymmetric reflection.

FIG. 3 is an evaluation analysis result of an X-ray diffractometer using a scintillation detector as a detector.

FIG. 4 is an evaluation analysis result of an X-ray diffractometer using a storage phosphor sheet as a detector.

FIG. 5 is a topographic image of an evaluation analysis result of an X-ray apparatus using a television camera as a detector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 X-ray generator 2 X-ray collector 3 Sample to be measured 4 X-axis horizontal movement mechanism 5 Y-axis horizontal movement mechanism 6 Z-axis horizontal movement mechanism 7 First tilt mechanism 8 Second tilt mechanism 9 Ψ-sample surface Inner rotation table 10 ω-scanning rotation axis 11 θ-scanning rotation axis 12 2θ-scanning rotation axis 13 Signal detector

Claims (5)

(57) [Claims] An X-ray generator, an X-ray collector made of at least one single crystal material, an orthogonal tilt mechanism in two directions, a horizontal moving mechanism in three directions connected to the tilt mechanism, and an X-ray collector. A sample stage having a horizontal movement mechanism and at least a sample in-plane rotation mechanism connected to the sample outside the tilting mechanism, and an arm of the sample stage attached to the sample stage.
A goniometer with a scanning rotation mechanism in the direction, a detector for detecting at least X-rays, a counting system with a counter,
An X-ray apparatus including a computer for performing control, measurement, and analysis. 2. The X-ray apparatus according to claim 1, wherein the counting system includes a storage phosphor sheet and a device for reading a signal from the storage phosphor sheet, and measures the diffracted X-ray. Characteristic X-ray diffraction device. 3. The X-ray apparatus according to claim 1, wherein the counting system includes an ultra-sensitive X-ray camera and an image processing apparatus for analyzing a topographic image from the X-ray camera,
An X-ray apparatus for measuring diffracted X-rays. 4. The X-ray fluorescence apparatus according to claim 1, wherein the counting system includes a semiconductor detector and an energy analyzer, and measures the fluorescence X-ray. 5. An evaluation analysis method using the X-ray apparatus according to claim 1, wherein the X-ray apparatus is connected to the tilt mechanism in two orthogonal directions of the apparatus. Using a three-way horizontal movement mechanism, the sample is set so that the normal vector of the crystal lattice plane and the rotation axis direction of the in-plane rotation mechanism coincide with each other. Using the in-plane rotation mechanism connected to the outside, the sample in-plane rotation mechanism is continuously rotated in-plane while satisfying the diffraction condition for the sample, and the obtained diffracted X-rays or fluorescent X-rays are counted by a counting system. A method for evaluating and analyzing diffracted X-rays or fluorescent X-rays, characterized by continuously measuring.