JPS61186900A - X ray microscope - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an X-ray microscope, and in particular to an XLf2 microscope that uses a phase contrast method in the X-ray region and can make the 21 contrast of a ×16 image suitable for observation. Regarding.

[Conventional technology]
It has been developed based on the strong demand for observation with VitrO. In conventional X-ray microscopes, a sample is irradiated with X-rays, the X-rays that have passed through the sample are printed onto a photoresist, and the image printed on the photoresist is observed using a scanning electron microscope. ing.

1. Problems to be Solved by the Invention" However, the contrast of the image obtained by this method is not sufficient, making it difficult to obtain an image suitable for observation.

The present invention has been made in view of the points mentioned above, and an object of the present invention is to provide an X-ray microscope that can obtain xim with sufficient contrast.

[Means for Solving the Problems] The X-ray microscope based on the present invention includes an X-ray source and an X-ray reflector that reflects X-rays from the X-ray source.
[an X-ray condensing system for forming an X-ray microspot;
an X-ray imaging system consisting of an X-ray reflecting mirror that reflects X-rays for imaging X-rays diffracted from the sample; A phase plate for controlling the phase and intensity of the next diffracted light, a moving means for moving the phase plate in a plane perpendicular to the optical axis of the microscope, and an intensity of X-rays transmitted through the phase plate and formed into an image. a means for detecting;
The present invention is characterized by comprising means for controlling the position of the phase plate in accordance with the detected X-ray intensity signal.

[Example code] An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

In FIG. 1, reference numeral 1 denotes, for example, a rotating anticathode type X-ray source, and among the X-rays generated from the X-ray source, X-rays traveling in a specific direction are completely absorbed by a first X-ray reflecting mirror 2. be reflected. The X-rays totally reflected by the first reflection mirror are totally reflected by the second X-ray reflection tIt3, and the optical axis 0
It is assumed that the X-rays are parallel to . The first and second X-ray reflections vt
2.3 are rotating bodies, which are integrally processed, for example,
The first reflecting mirror 2 is a hyperbolic mirror of revolution, and the second reflecting mirror 3 is a parabolic mirror of revolution. The X-rays parallel to the optical axis are
The light is focused onto the sample 6 by the fourth X-ray reflecting mirrors 4 and 5. In this embodiment, the third reflecting mirror vL4 is a paraboloid of revolution, and the fourth reflecting mirror 5 is a hyperboloid of revolution. Here, 7 is an X-ray shielding member for shielding X-rays other than the X-rays totally reflected by the first and second reflecting mirrors 2 and 3, and 8 is a member for shielding X-rays other than the X-rays totally reflected by the first to fourth reflecting mirrors. This is a diaphragm plate placed on the focal plane of the X-ray condensing system, and the diaphragm plate 8 has a second
As shown in the figure, a ring-shaped slit 9 is provided. When the sample 6 is irradiated with X-rays, the X-rays diffracted from the sample 6 are totally reflected by the fifth and sixth reflecting mirrors 10.11, but the fifth reflecting mirror 10 is a rotating mirror. The sixth reflecting mirror 11 is a spheroidal mirror, and the fifth and sixth reflecting mirrors 11 are curved mirrors. )It? 1 constitutes an imaging system for X-rays diffracted from the sample 6. Reference numeral 12 denotes a phase plate arranged at the focal plane of the imaging system consisting of the fifth and sixth reflecting mirrors 10° and 11, and 13 is arranged at the imaging position of the X-ray image by the imaging system. , is a fluorescent screen that generates light when X-rays are incident on it. The phase plate 12 is moved two-dimensionally in a direction perpendicular to the optical axis O of the microscope by the moving mechanism 30. The surface of the fluorescent screen emits light due to the diffracted X-rays imaged on the fluorescent screen 13, and this light emission is detected by the photodetector 31. The output signal of the detector 31 is supplied to a computer 33 via a signal processing circuit 32 consisting of an amplifier, an AD converter, etc. Incidentally, if a reflecting mirror whose surface is provided with a multilayer film is used as each reflecting mirror, the amount of condensed X[I can be increased.

In the configuration described above, among the X-rays generated from the X-ray source 1, Xm emitted in a specific direction is totally reflected by the first and second X-ray reflecting mirrors 2 and 3, and is reflected parallel to the optical axis. NaX
Furthermore, since other X-rays are blocked by the X-ray shielding plate 7, the aperture plate 8 is irradiated with ring-shaped X-rays. The ring-shaped X-rays are transmitted through the aperture plate 8
The X-rays are shaped by passing through the slit 9, and only the shaped X-rays are focused on a minute point on the sample 6 by the third and fourth reflecting mirrors 4.5.

The X-rays irradiated to the sample 6 depend on the thickness of the sample, or
It is diffracted according to the difference in its constituent components. The diffracted light is imaged onto the phosphor plate 13 by the fifth and sixth reflecting mirrors io and 1i, but the X-rays directed toward the phosphor plate are restricted by the phase plate 12.

According to Abbe's theory of a microscope, its resolution is determined by whether or not the grooves are visible when a diffraction grating is placed as a sample. The diffracted light that is irradiated onto the diffraction grating serving as the sample forms a diffraction image on the normal plane of the objective mirror. Figure 3 shows the 0th order, ±1, formed on this normal plane.
The next diffraction image 14°15.16 is shown, and this diffraction image is collected and formed into an image at the image plane of the objective mirror. Here, when the sample is a phase grating, the phase of the first-order diffracted light is shifted by 90 degrees from the zero-order light. The phase plate 12 shown in FIG. 1 weakens the intensity of this O-order diffracted light and changes its phase by 90°.
The objective is to increase the contrast of the diffraction image by changing the diffraction light so that it has the same phase as the first-order diffraction light, and causing these diffraction lights to interfere on the image plane. The shape of the phase plate 12 is
In the figure, reference numeral 17 denotes a ring-shaped aperture, and the aperture 111 is arranged so that the X-rays totally reflected from the reflection 1210.11 constituting the imaging system can pass therethrough.

FIG. 5 shows the diffraction image formed on the phase plate 12, where 18 indicates the 0th-order diffracted light, 19 indicates the +1st-order diffracted light, and 20 indicates the 11th-order diffracted light. As is clear from this figure, the optical axis of the imaging system, that is, the center of the ring-shaped aperture 17 provided in the phase plate 12, and the central axis of the O-order diffracted light from the sample 6 are offset. , ring-shaped 0th order diffracted light 1
8 are all prevented from passing through the ring-shaped opening 17. The ring-shaped aperture 17 is provided with a shielding portion 22 for restricting X-rays passing through a region 21 where the aperture 17 and the O-order diffracted light intersect. The shielding portion 22 has a plurality of microcircular X-ray passing portions 23, and each of the X-ray passing portions 23 has a function of reducing the intensity of the transmitted X-rays and changing the phase thereof by 90°. A thin non-metallic film is attached with a thickness that allows The size of this X-ray passage section 23.

The number etc. are determined according to the intensity of the +1st order and -1st order diffracted light. In FIG. 5, the diffracted light passing through the region 24 intersecting with the first and second order diffracted lights of the ring-shaped aperture 17 reaches the fluorescent screen 13 shown in FIG. 1, and its intensity and phase are adjusted by the phase plate 12. Since the light interferes with the O-order diffracted light and increases its intensity, an image with good contrast is displayed on the fluorescent screen 13.

By the way, if the phase plate 12 is not placed at an appropriate position, an image with good contrast will not be formed. Therefore, in this embodiment, the phase plate 12 is connected to the computer 33.
The drive mechanism 30 moves the lens two-dimensionally within a plane perpendicular to the optical axis 0 based on a command from the drive mechanism 30 . At this time, when the ring-shaped space]]17 of the phase plate 12 coincides with the O-order diffracted light,
Most of the O-order diffracted light with high intensity passes through the aperture 17 and enters the fluorescent screen 13, and the maximum intensity light is generated from the fluorescent screen. Furthermore, when the apertures 17 are arranged at optimal positions with respect to each diffraction ring, the contrast of the formed X-ray image becomes stronger and the amount of light from the fluorescent screen 13 increases. On the other hand, when the phase plate 12 is misaligned and there is insufficient interference between the 0th-order diffracted light and other diffracted lights, only a small amount of light is generated. 6th
The figure shows an example of the detection signal of the detector 31, where the peak Δ is when the ring-shaped aperture 17 and the O-order diffracted light match, and the peak B is when the phase plate 12 is optimally arranged for each diffracted light. It is from when it was done. The computer 33 can know the optimum position of the phase plate 12 from this detection signal,
Instructs the drive mechanism 30 to change the position of the phase plate 12 to peak B.
Set to the position when detected. After that, the fluorescent screen 13
If the X-ray film is placed at this position, an XrA image with extremely high contrast can be obtained.

Note that the present invention is not limited to the embodiments described above, and can be modified in many ways. For example, although a diaphragm plate with a ring-shaped slit is placed in the normal plane of the X-ray condensing system, the light generated from the optical system consisting of the X-ray reflecting mirror 2, 3° and the X-ray shielding plate 7 shown in FIG. If there are few stray X-ray peaks, this aperture plate is not necessarily necessary. Also, diffracted X-rays are focused on a fluorescent screen. However, instead of a fluorescent screen, a diffraction
An arrangement may also be made in which an Xa image pickup tube is placed at the line junction position and the X-ray intensity is determined by a signal from the image pickup tube. Furthermore, the shape of the zero-order analysis passage section 23 provided in the opening of the phase plate is not limited to a circle, but may be square, diamond, or the like. Furthermore, although the phase of the 0th-order diffracted light is shifted so that the diffraction image is strengthened by interference, the phase of the 0th-order diffracted light may be changed so that the diffracted light is weakened by interference.

[Effect Song 1 As described in detail below, in the present invention, a phase plate is placed in the focal plane of the X-ray imaging system, and the intensity and phase of the O-order diffracted light from 1 are adjusted by the phase plate. As a result, 1:7 X-ray images with good contrast can be obtained.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the optical system of an X-ray microscope based on the present invention;
Figure 2 shows the shape of the aperture plate, Figure 3 shows the diffracted light, Figure 4 shows an enlarged view of the phase plate without showing its shape, and Figure 5 shows each diffracted light on the phase plate. 6 are diagrams showing signal waveforms corresponding to X-ray intensity. 1...X-ray source

Claims (5)

[Claims] (1) An X-ray condensing system consisting of an X-ray source and an X-ray reflecting mirror that reflects X-rays from the X-ray source to form a minute X-ray spot on the sample, and a diffraction system from the sample. An X-ray imaging system consisting of an X-ray reflecting mirror that reflects the X-rays to image the X-rays, and an a phase plate for controlling the phase plate and the intensity; a moving means for moving the phase plate in a plane perpendicular to the optical axis of the microscope;
An X-ray microscope comprising means for detecting the intensity of rays and means for controlling the position of the phase plate in response to the detected X-ray intensity signal. (2) The X-ray microscope according to claim 1, wherein the X-ray reflecting mirror is a rotating body, and the sample is irradiated with ring-shaped X-rays. (3) The X-ray microscope according to Claims 1 and 2, further comprising an aperture plate having a slit to limit the X-rays irradiated onto the sample. (4) The X-ray microscope according to any one of claims 1 to 3, wherein the X-ray imaging system is arranged so that its optical axis does not coincide with the central axis of the zero-order diffracted light from the sample. (5) The phase plate has a ring-shaped aperture through which the X-rays emitted from the X-ray imaging system pass, and the phase plate has a phase in the portion through which the 0th-order diffracted light passes through the ring-shaped aperture. The X-ray microscope according to claim 4, further comprising a controlling thin film.