JP5482367B2 - Sample structure for X-ray hologram imaging and manufacturing method thereof. - Google Patents

Description

  The present invention relates to a sample structure for imaging an X-ray hologram and a manufacturing method thereof.

  The holographic measurement that divides the coherent light into the reference light and the object light passing through the sample, creates a hologram by the interference of the diffracted light of the object light and the reference light, and obtains knowledge of the sample structure by inverse Fourier transform. It is widely used for analyzing the microstructure of samples. X-ray holography measurement using X-rays instead of long-wavelength light such as infrared light has excellent resolution because of the short wavelength of X-rays, and also has a large sample transmission power. It is expected to be useful for analyzing the fine structure of a semiconductor device or the magnetic domain structure of a magnetic film.

  However, since the coherence length of X-rays that can be easily used at present is shorter than that of infrared light, in order to split incident X-rays into coherent object light and reference light, the object light and reference light are divided into X It is necessary to divide within a small area within the coherence length of the line, for example, within an area within several μm.

  FIG. 11 is a cross-sectional view of a conventional sample structure for X-ray hologram imaging, showing the structure of a sample support on which a thin film sample is mounted.

  Referring to FIG. 11, in the conventional sample structure for X-ray hologram imaging, a thin film sample 4 is formed on the upper surface of a support substrate 3 that transmits X-rays, and a shielding layer 2 that shields X-rays is formed on the lower surface. Yes. The shielding layer 2 and the support substrate 3 function as a support base 1 that supports the thin film sample 4.

  The shielding layer 2 is provided with a transmission window 5 that transmits object light, and is further provided with a reference light hole 106 that vertically penetrates the thin film sample 4 and the support base 1 in the vicinity of the transmission window 5. Then, the structure (sample pattern 4 a) formed on the thin film sample 4 is formed on the transmission window 5. X-rays enter from the lower surface (side with the shielding layer 2), X-rays transmitted through the transmission window 5 become object light, and X-rays that have passed through the reference light hole become reference light.

JP 2009-210538 A

S. Eisebitt, J.M. Lunng, W.L. F. Schlotter, M.M. Lorgen, O .; Hellwig, W.M. Eberhardt, J. et al. Stohr, Nature, Vol. 432, p. 885,2004

  In the holographic measurement using the reference light described above, the resolution of the reproduced image increases as the cross-sectional area of the reference light, that is, the reference light hole 106 becomes smaller. Therefore, it is desirable to form a small reference beam 106. The reference light hole 106 is established by a focused ion beam processing method that allows fine processing.

  However, since the shielding layer 2 is thick, the aspect ratio of the reference light hole 106 penetrating the shielding layer 2 is large, and it is difficult to reduce the reference light hole 106 until the resolution is sufficiently satisfied. In particular, when using short-wavelength X-rays to improve resolution and transmission power, the shielding layer 2 must be thickened to sufficiently shield X-rays, and it is difficult to open a small reference light hole.

  The present invention relates to a sample structure used for holographic measurement using reference light and a method for manufacturing the same, and a sample structure capable of effectively opening a small reference light hole in a sample structure having a thick shielding layer, and the manufacture thereof. It aims to provide a method.

  According to the first aspect, the sample structure of the present invention for solving the above-described problem causes X-rays to interfere with the X-ray diffracted light of the reference light and the X-ray diffracted light transmitted through the thin film sample. In a sample structure for X-ray hologram imaging for imaging a hologram, an upper surface and a lower surface are main surfaces, a support substrate that transmits the X-rays, and the X-ray formed on the lower surface of the support substrate A shielding layer for shielding; a transmission window that penetrates the shielding layer and exposes the support substrate on a bottom surface; the thin film sample formed on an upper surface of the support substrate; and the X-ray incident on the transmission window A reference light hole that is opened in a region within the coherence length of the light source and obliquely penetrates the shielding layer, the support substrate, and the sample thin film with respect to the main surface, and allows the reference light to pass therethrough, When viewed from the vertical direction of the main surface of the support substrate, the upper and lower openings of the reference light hole Shape is provided as a sample structure for X-ray hologram imaging to partially superimposed.

  According to the second aspect, the X-ray hologram imaging sample structure for imaging the X-ray hologram by causing the X-ray diffracted light of the reference light and the X-ray diffracted light transmitted through the thin film sample to interfere with each other. In the body, an upper surface and a lower surface are main surfaces, a support substrate that transmits the X-rays, a shielding layer that shields the X-rays formed on the lower surface of the support substrate, and formed through the shielding layer. A transmission window that exposes the support substrate on the bottom surface, the thin film sample formed on the top surface of the support substrate, and a region within the coherence length of the X-ray incident on the transmission window, A vertical through hole penetrating the shielding layer, the support substrate and the sample thin film perpendicularly to the main surface, and the vertical through hole so as to close an opening on the upper surface side of the support substrate of the vertical through hole. The shielding layer extending on the upper surface of the support substrate around the cover Thin and X-ray shielding film comprising a shielding material Ri, wherein the shielding film through the reference light and the hole for passing the reference beam, are provided as a sample structure of the X-ray hologram imaging with.

  According to the present invention, since the reference light hole is formed obliquely, X-rays that enter perpendicularly can be passed to obtain reference light having a small cross section. Therefore, a transmitted light hole having a small effective area can be easily formed in the hot shielding layer.

  According to another aspect, the transmitted light hole is formed in a thin shielding thin film that covers the large vertical through hole, so that a small transmitted light hole can be easily formed.

Sectional drawing of the sample structure of 1st Embodiment of this invention Partial enlarged plan view of the sample structure of the first embodiment of the present invention Sectional drawing of manufacturing process of sample structure of first embodiment of the present invention 1 is a configuration diagram of an X-ray hologram imaging apparatus according to a first embodiment of the present invention. Sectional drawing of the sample structure of 2nd Embodiment of this invention Sectional drawing of the manufacturing process of the sample structure of 2nd Embodiment of this invention Reconstructed image of the first embodiment of the present invention Reconstructed image of the second embodiment of the present invention Reconstructed image of conventional holographic measurement Reconstructed image of other conventional holographic measurements Sectional view of a conventional sample structure for X-ray hologram imaging

  1st Embodiment of this invention is related with the X-ray holography measurement using the sample structure which has the permeation | transmission light hole penetrated diagonally.

  FIG. 1 is a cross-sectional view of the sample structure according to the first embodiment of the present invention, showing the structure of a transmission window and a reference light hole. FIG. 2 is a partially enlarged plan view of the sample structure according to the first embodiment of the present invention, and shows a structure in which the reference light hole of the sample structure shown in FIG. 1 is viewed from above in FIG.

  Referring to FIG. 1, a sample structure 10 used in the first embodiment includes a support base 1 including a support substrate 3 provided on a shielding layer 2, and a thin film sample 4 formed on the support base 1. And have.

  The shielding layer 2 preferably has an X-ray transmittance that can be handled as X-ray shielded in X-ray holography measurement, for example, an X-ray transmittance of 1% or less. In addition, since the X-ray which permeate | transmits the shielding layer 2 becomes the noise of a holography measurement, and reduces a measurement precision, it is desirable that X-ray transmittance is low. On the other hand, in order to easily form the reference light hole 6 having a small cross section, it is preferable to reduce the aspect ratio of the reference light hole 6 by reducing the thickness of the shielding layer 2.

  In order to satisfy the requirements of both the small X-ray transmittance and the thin layer thickness required for such a shielding layer 2, the shielding layer 2 is a heavy metal having a large X-ray absorption coefficient, for example, tantalum, tungsten, iridium, platinum or gold. Is preferably used. The X-ray transmittance of the shielding layer 2 made of these heavy metals and having a thickness of 1 μm is shown below. Here, the photon energy of the X-ray is 700 eV. In addition, atomic number and density are written together in this order in parentheses.

The X-ray transmittance of the shielding layer is
In the case of tantalum (73, 16.7 g / cm ² ), 6.12 × 10 ⁻⁶ ,
4.87 × 10 ^{−7 for} tungsten (74, 19.3 g / cm ² )
In the case of iridium (77, 22.4 g / cm ² ), 9.35 × 10 ⁻⁹ ,
In the case of platinum (78, 21.5 g / cm ² ), 1.24 × 10 ⁻⁸ ,
2.35 × 10 ⁻⁸ in the case of gold (79, 19.3 g / cm ² )
It is. Therefore, by setting the shielding film 2 made of these heavy metals to a thickness of 1 to 2 μm, X-ray shielding sufficient for holographic measurement is performed. In the first embodiment, a gold layer having a thickness of 2 μm is used as the shielding layer 2.

  The shielding film 2 is provided with a transmission window 5 and a reference light hole 6. The transmission window 5 is formed of, for example, a 2.0 μm × 2.0 μm rectangular hole penetrating the shielding film 2, and the support substrate 3 is provided on the bottom surface (surface on the interface side between the support substrate 3 and the shielding layer 2 in FIG. 2). Is expressed. The reference light hole 6 will be described later.

  The support substrate 3 supports the thin film sample 4 provided thereon, and has mechanical strength necessary for support and high X-ray transmittance. As the support substrate 3, for example, a silicon substrate having a thickness of 0.5 μm to 5 μm, a silicon nitride membrane having a thickness of 0.1 μm to 1 μm, or a polymer resin film having a thickness of several μm to several tens μm can be used. Here, a silicon substrate having a thickness of 1 μm was used as the support substrate 3. The X-ray transmittance of the silicon substrate having a thickness of 1 μm is 0.378 with respect to X-rays having a photon energy of 700 eV, and is sufficiently transparent to X-rays as the support substrate 3 for X-ray holography measurement.

  The thin film sample 4 is an object to be measured for X-ray holography measurement, and can be composed of, for example, a metal thin film, a semiconductor thin film, or a magnetic film. Of course, any thin film that causes an absorption or phase change distribution to X-rays can be used as the thin film sample 4. Here, a metal film having a thickness of 50 nm, for example, a gold film, was used as the thin film sample 4, and the portion to be measured was patterned to form a metal pattern 4a. The metal pattern 4 a is formed immediately above the transmission window 5, that is, at a position included in the opening area of the transmission window 5. Further, the thin film sample 4 may be formed at least in the opening region of the transmission window 5, and does not need to cover the entire upper surface of the support substrate 3.

  The reference light hole 6 is opened through the sample structure 10 obliquely up and down. In other words, the reference light hole 6 is opened with the angles θx and θy inclined from the vertical direction of the upper surface of the sample structure 10 in the X-axis and Y-axis directions, respectively. Here, the Z-axis was in a direction perpendicular to the upper surface of the sample structure 10, the Y-axis was in the direction from the reference light hole 6 toward the transmission window 5, and the X-axis was perpendicular to the Z-axis and Y-axis.

  With reference to FIG. 2, the opening shape 6 a of the reference light hole 6 opening on the upper surface of the sample structure 10 and the opening shape 6 b of the reference light hole 6 opening on the lower surface of the sample structure 10 are the reference light hole 6. Since the central axes of these are inclined by the angles θx and θy from the Z axis, they are shifted from each other when viewed from the Z axis direction. In this structure, among the X-rays incident parallel to the Z axis, the X-rays incident on the overlapping region 6c where the upper and lower opening shapes overlap are transmitted in the vertical direction without being shielded. On the other hand, among the X-rays that enter the inner regions of the opening shapes 6a and 6b, the X-rays that enter the outside of the overlapping region 6c are shielded by the inclined wall surface of the reference light hole 6 and cannot be transmitted. That is, the reference light hole 6 of the first embodiment functions as a substantial reference light hole that allows only the region 6c where the upper and lower opening shapes 6a and 6b of the reference light hole 6 overlap to pass X-rays. The overlapping region 6c is smaller than the cross section of the reference light hole 6 (for example, the opening shapes 6a and 6b). For this reason, the effective reference light hole 6 can be made smaller than the reference light hole 6 actually formed. Therefore, the minute reference light hole 6 can be easily formed.

  In the first embodiment, the processing hole of the reference light hole 6 is a rectangle of 0.2 μm × 0.2 μm and the angles θx and θy are 4.5 degrees, so that the sample structure 10 having a thickness of approximately 2 μm. In addition, a rectangular overlapping region 6c of 0.04 μm × 0.04 μm could be formed.

  The reference beam hole 6 and the transmission window 5 described above are arranged in the range of the coherence length of X-rays used for creating a hologram. If the distance between the reference light hole 6 and the transmission window 5 exceeds the coherence length, a hologram is not created. If the distance is too short, images reproduced from the hologram overlap and analysis becomes difficult. The coherence length varies depending on the X-ray source and is preferably determined experimentally. In addition, the presence or absence of overlapping images can be confirmed by simulating image reproduction. Considering the coherence length and the overlap of the reconstructed image, for example, in the case of X-rays with a photon energy of 400 eV to 1200 eV that reduces the orbital radiation to X-rays, if the size of the transmission window 5 is 2 μm × 2 μm, reference When the distance between the light hole 6 and the transmission window 5 is about 5 μm and the size of the transmission window 5 is 0.2 μm × 0.2 μm, the distance between the reference light hole 6 and the transmission window 5 is preferably about 1 μm. . In the first embodiment, the distance between the reference light hole 6 and the transmission window 5 is 0.8 μm.

  Next, a method for manufacturing the sample structure 10 of the first embodiment will be described.

  FIG. 3 is a cross-sectional view of the manufacturing process of the sample structure according to the first embodiment of the present invention, and shows the manufacturing process of the sample structure 10 described above.

  With reference to FIG. 3A, in the manufacturing method of the sample structure 10 of the first embodiment, first, a gold layer having a thickness of 50 nm, for example, is formed on the upper surface of the support substrate 3 made of a silicon substrate by sputtering or vapor deposition. A thin film sample 4 is formed. Next, the thin film sample 4 was patterned to form a pattern 4 a on the region where the transmission window 5 was to be formed. The thin film sample 4 may be a thin film to be measured. For example, the thin film sample 4 may be a magnetic film, a semiconductor thin film, or a metal pattern.

  Next, referring to FIG. 3B, the entire thickness of the lower surface of the support substrate 3 was removed by etching, for example, by ion etching to reduce the film thickness, thereby forming the support substrate 3 having a thickness of 1 μm. In addition, the thickness of the support substrate 3 is usually set to 0.5 to 5 μm in consideration of the X-ray transmittance.

  Next, referring to FIG. 3C, the shielding layer 2 made of heavy metal, for example, gold and having a thickness of 2 μm was formed on the lower surface of the support substrate 3. The shielding layer 2 can be formed by, for example, a vacuum deposition method, a sputtering method, or a plating method.

  Next, referring to FIG. 3 (d), the lower surface of the shielding layer 2 is irradiated with, for example, a Ga focused ion beam 51 to open a transmission window 5 that penetrates the shielding layer 2. In addition, in order to completely remove the shielding layer 2 when the transmission window 5 is opened, the lower surface of the support substrate 3 exposed on the bottom surface of the transmission window 5 is also over-etched. On the other hand, the upper layer of the support substrate 3 is left. This prevents the thin film sample 4 formed on the upper surface of the support substrate 3 from being damaged by the focused ion beam etching. The completion of the opening of the transmission window 5 can be known from, for example, the ratio of gold constituting the shielding layer 2 and silicon atoms constituting the support substrate 3 observed in the secondary ions.

  Next, referring to FIG. 3E, a focused ion beam is irradiated from directions perpendicular to the lower surface perpendicular direction of the shielding layer 2 to the X and Y axis directions at angles θx and θy, respectively. 3 and the reference light hole 6 that obliquely penetrates the thin film sample 4 were formed.

  The sample structure 10 according to the first embodiment is manufactured through the above steps. Note that the cross section of the focused ion beam expands as it moves away from the focal point. For this reason, referring to FIG. 2, the opening 6b on the incident side of the focused ion beam is wide and the opening 6a on the opposite side tends to be narrow. Therefore, in order to form the precise reference beam hole 6, the characteristics of the focused ion beam etching apparatus are experimentally grasped in advance, and the size and angles θx and θy of the reference beam hole 6 are appropriately determined according to the characteristics. It is desirable.

  FIG. 4 is a configuration diagram of the X-ray hologram imaging apparatus according to the first embodiment of the present invention, and shows the main configuration of the X-ray hologram imaging apparatus.

  Referring to FIG. 4, in the X-ray hologram imaging apparatus of the first embodiment, the CCD imaging panel 11 and the sample structure 10 are arranged in parallel with the thin film sample 4 and the imaging surface of the imaging panel 11 facing each other. Has been.

  A part of the coherent X-ray 12 incident from the lower surface (left side in FIG. 4) of the sample structure 10 is transmitted through the transmission window 5 and the thin film sample 4 to become object light 12a ′, and the other part. Passes through the reference light hole 6 and becomes reference light 12b ′. The object beam 12a 'and the reference beam 12b' reach the point P on the imaging panel 11 as diffracted beams 12a and 12b and interfere with each other to create a hologram on the imaging panel 11.

As is well known, the X-ray electrolysis strength Ep at the point P on the imaging panel 11 is the X-ray (on the right surface of the thin film sample 4 shown in FIG. 4) of the sample structure 10 on which the thin film sample 4 is provided. The electrolytic intensity of the object light 12a ′ and the reference light 12b ′, if necessary, X-rays passing through the region shielded by the shielding layer 2) is defined as Em.
Ep (X, Y) = (1 / iλ) ∬ [Em (x, y) ×
× (1 / r) × exp (ikr) × cos α] dxdy (1)
And the Fourier transform of the electrolytic strength Em (x, y). Here, X, Y and x, y represent the position coordinates in the surface of the imaging panel 11 and the position coordinates in the surface of the sample structure 10, respectively, λ represents the X-ray wavelength, and k represents the wave number. Further, r represents the distance from the surface of the sample structure 10 to the point P, α represents the angle (diffraction angle) formed by the diffracted light 12a, 12b and the incident X-ray 12, and the integration range is the entire surface of the sample structure 10. It is.

Furthermore, the expression (1) is an approximate expression,
Ep (X, Y) ≈ (exp (ikZo) / iλZo) × ∬ [Em (x, y) ×
Xexp (ik ((X−x) ² + (Y−y) ² ) / 2Z)] dxdy (2)
It is represented by Here, Zo represents the distance from the surface of the sample structure 10 to the imaging panel surface.

  The hologram recorded by the imaging panel 11 is recorded according to the electric field intensity Em (x, y) displayed by the Fourier transform (1). Therefore, the electrolytic intensity Em (xy) is calculated as a reproduced image by inverse Fourier transform of this hologram. The reconstructed image calculated by this inverse transformation reproduces the X-ray intensity distribution, that is, the X-ray absorption distribution by the thin film sample 4, as well as the X-ray phase change, that is, the X-ray phase modulation by the thin film sample 4. ing. In the first embodiment, the inverse transformation is calculated by a computer using the approximate expression (2).

  The second embodiment of the present invention relates to an X-ray holographic measurement using a sample structure in which a transmitted light hole is formed in a thin shielding thin film covering a vertical through hole.

  FIG. 5 is a cross-sectional view of the sample structure according to the second embodiment of the present invention. FIG. 5A shows the structure of the transmission window and the reference light hole of the sample structure. FIG. 5B shows a partially enlarged view of the structure of the reference light hole of the sample structure shown in FIG.

  Referring to FIG. 5A, the sample structure 20 used in the second embodiment is formed on a support base 1 composed of a support substrate 3 provided on the shielding layer 2 and on the support base 1. A thin film sample 4. The shielding layer 2 has a transmission window 5 that penetrates the shielding layer 2 and exposes the support substrate 3 on the bottom surface. A metal pattern 4 a made of the thin film sample 4 is formed on the thin film sample 4 located immediately above the transmission window 5. The above-described configuration of the sample structure 20 is the same as that of the sample structure 10 of the first embodiment.

  The sample structure 20 of the second embodiment is different from the sample structure 10 of the first embodiment with respect to the reference light hole 9 and the vertical through-hole 7 opened therebelow.

  5A and 5B, in the sample structure 20 of the second embodiment, the shielding layer 2, the support substrate 3, and the thin film sample 4 are vertically penetrated through the upper and lower surfaces of the sample structure 20. A vertical through hole 7 is provided. The vertical through hole 7 is formed in a cross section having a size that can be formed by focused ion beam etching, for example, a square shape of 0.2 μm × 0.2 μm. The vertical through hole 7 is formed at the same position (positional relationship with the transmission window 5) as in the first embodiment, and the shape thereof can be the same as that of the reference light hole 106 of the conventional sample structure 110. .

  A shielding thin film 8 made of a metal film that covers the upper surface of the opening of the vertical through-hole 7 and extends on the thin film sample 4 around the opening is provided. The shielding thin film 8 is made of, for example, heavy metal like the shielding layer 2 and is thinner than the shielding layer 2, for example, a thin film having a thickness of about 1/10 of the shielding layer 2. Therefore, the shielding thin film 8 cannot shield the incident X-rays as much as the shielding layer 2 and transmits the X-rays to some extent.

  Further, the shielding thin film 8 is provided with a reference light hole 9 penetrating the shielding thin film 8 having a square cross-sectional shape of, for example, 0.04 μm × 0.04 μm smaller than the vertical through hole 7. Since the reference light hole 9 is formed in the shielding thin film 8 thinner than the shielding layer 2, the aspect ratio of the reference light hole 9 is smaller than the direct opening in the shielding layer 2 because the thickness is smaller. Therefore, it is possible to easily form the small reference light hole 9 as compared with the conventional reference light hole 106 provided in the shielding layer 2. For example, conventionally, when a 0.2 μm × 0.2 μm reference beam hole 106 can be opened in the shielding layer 2, the same shielding layer 2 material is used to form the shielding thin film 8 having a thickness of 1/10. The reference light hole 106 of 0.02 μm × 0.02 μm can be opened in the shielding thin film 8.

  In the sample structure 20 of the second embodiment, the shielding thin film around the reference light hole 9 transmits X-rays to some extent. However, the area of the shielding thin film 8 that transmits X-rays is limited by the vertical through-hole 7. Further, the thickness of the shielding thin film 8 is also set to about 1/10 of the shielding layer 2. Even if the X-rays passing through the shielding thin film 8 having such a thickness and area are ignored, the accuracy does not deteriorate so much as is problematic for holographic measurement. Of course, in the inverse Fourier transform, the accuracy can be improved by taking the X-ray passing through the shielding thin film 8 as a calculation target.

  Next, a method for manufacturing the sample structure 20 of the second embodiment described above will be described.

  FIG. 6 is a cross-sectional view of the manufacturing process of the sample structure according to the second embodiment of the present invention, and shows the manufacturing process of the sample structure 20.

  With reference to FIG. 6A, in the manufacturing process of the sample structure 20 of the second embodiment, first, the thin film sample 4 having the metal pattern 4a formed on the upper surface of the support substrate 3 is formed, and then the support is performed. The shielding layer 2 is formed on the lower surface of the substrate 3 and a transmission window 5 penetrating the shielding layer 2 is opened. The structure and material of the sample structure 20 at the end of this step are the same as those of the sample structure 10 of the first embodiment shown in FIG.

  Next, referring to FIG. 6 (b), a vertical through hole 7 is formed in the vicinity of the transmission window 5 so as to vertically penetrate the shielding layer 2, the support substrate 3, and the thin film sample 4. The vertical through hole 7 was formed at the same position as the reference light hole 6 of the sample structure 10 of the first embodiment. Further, the vertical through-hole 7 can be formed by irradiating the focused ion beam 51 perpendicularly from the lower surface of the shielding layer 2 to the lower surface of the shielding layer 2. In addition, it is preferable that the vertical through-hole 7 has a cross section as small as possible from the viewpoint of accuracy of holographic measurement.

  Next, referring to FIG. 6 (c), the source gas of CVD (Chemical Vapor Deposition) is supplied to the upper surface of the thin film sample 4 in the vicinity where the vertical through hole 7 is opened, and the vicinity of the vertical through hole 7. Then, the electron beam or ion beam 52 was irradiated from above the thin film sample 4. The electron beam or ion beam 52 excites the source gas and deposits a metal (for example, Au) in the vicinity of the upper end opening of the vertical through hole 7. The deposited metal is deposited so as to close the upper end opening of the vertical through hole 7 from the periphery of the upper end opening of the vertical through hole 7, thereby forming a shielding thin film 8 having a thickness of, for example, 0.1 μm. .

  Next, referring to FIG. 6 (d), using the focused ion beam 51 again, for example, a 0.04 μm square reference light hole 9 penetrating the shielding thin film 8 was formed. As described above, since the thickness of the shielding thin film 8 is thin, the fine reference light hole 9 can be easily opened. Through the above steps, the sample structure 20 of the second embodiment was manufactured.

  Hereinafter, evaluation results of holographic measurement using the above-described sample structures 10 and 20 of the present invention will be described.

  This holographic measurement is evaluated by imaging a hologram using the sample structures 10 and 20 of the present invention, creating a reproduced image by Fourier transform of the hologram, and comparing the reproduced image with the sample pattern 4a. went. The hologram was imaged using a CCD imager, and the Fourier transform was calculated using a personal computer.

  FIG. 7 is a reconstructed image of the first embodiment of the present invention, and represents a reconstructed image created by Fourier transform of a hologram imaged using the sample structure 10 of the first embodiment. FIG. 8 is a reconstructed image of the second embodiment of the present invention, and represents a reconstructed image created by Fourier transform of a hologram imaged using the sample structure 20 of the second embodiment. 7A and 8A show the sample pattern 4a, and FIGS. 7B and 8B show the reproduced image. The rectangular figure (outline figure) at the center of the reproduced image is a 0th-order diffraction image, and the white figure in the same arrangement as the sample pattern 4a on the left side is a real image, and is arranged in the upside down direction on the left side. The white figure is a virtual image.

  In the evaluation of this holographic measurement, as the sample pattern 4a, referring to FIGS. 7A and 8A, a slit-shaped opening provided in the thin film sample 4 made of Au was used. This sample pattern 4a has lengths in the Y-axis and X-axis directions from six rectangular openings of 200 nm × 200 nm, 100 nm × 200 nm, 80 nm × 200 nm, 60 nm × 200 nm, 40 nm × 200 nm, 20 nm × 200 nm, respectively. Become.

  With reference to FIG. 7A and FIG. 8B, the hologram reproduction image using the sample structure 10 of the first embodiment has six short sides formed in the sample pattern 4a from 200 nm to 20 nm. All the openings are reproduced. That is, it has a resolution of 20 nm or less.

  The sample structure 10 of the first embodiment evaluated here has a rectangular (square) reference light hole 6 of 0.2 μm × 0.2 μm opened at a position 0.8 μm away from the transmission window 5. The effective size of the reference light hole 6 (the size through which X-rays perpendicularly incident on the sample structure 10 are transmitted) is a rectangle (square) of 0.04 μm × 0.04 μm. In addition, the sample structure 20 of the second embodiment has a 0.04 μm × 0.04 μm rectangular (square) reference light hole 9 opened at a position 0.8 μm away from the transmission window 5.

  FIG. 9 is a reproduction image of a conventional holographic measurement, using a conventional sample structure 110 having a rectangular reference light hole 106 of 0.2 μm × 0.2 μm opened at a position 50 μm away from the transmission window 5. The reproduced image of the captured hologram is shown. FIG. 10 is a reproduction image of another conventional holographic measurement, and the other conventional image having a 0.2 μm × 0.2 μm rectangular reference light hole 106 opened at a position 0.8 μm away from the transmission window 5. The reproduced image of the hologram imaged using the sample structure 110 is shown. 9A and 10A show the sample pattern 4a, and FIGS. 9B and 10B show the reproduced image.

  Referring to FIG. 9, when the distance between transmission window 5 and reference light hole 106 is 50 μm, the reproduced image is not reproduced. This is because the transmission window 5 and the reference light hole 106 are too far apart, and the coherence between the object light 12 a ′ passing through the transmission window 5 and the reference light 12 b ′ passing through the reference light hole 106 is small.

  On the other hand, referring to FIG. 10, when another conventional sample structure 106 in which the distance between the transmission window 5 and the reference light hole 6 is 0.8 μm as in the first and second embodiments is used, it is unclear. A reconstructed image was created. This is because the transmission window 5 and the reference light hole 6 are within the coherence length and the effective cross-sectional shape of the reference light hole 106 is as large as 0.2 μm × 0.2 μm, so that the accuracy of the holographic measurement is deteriorated. It is shown that.

  As described above, since the sample structures 10 and 20 of the first and second embodiments have the reference light holes 6 and 9 that are effectively smaller than the conventional sample structure 110, holographic measurement using them. Then, it is possible to create a precise reproduction image.

  Further, the sample structure 10 of the first embodiment easily forms the reference light hole 6 that effectively functions as the small reference light hole 6 by forming the relatively large reference light hole 6 that can be easily formed obliquely. Can be formed. Furthermore, in the sample structure 20 of the second embodiment, since the reference light hole 9 is formed in the thin shielding thin film 8, the small reference light hole 9 can be easily formed.

  By applying the present invention to a sample support structure used for holographic measurement of a thin film magnetic body, a semiconductor thin film, or wiring of a semiconductor device, highly accurate holographic measurement can be realized.

DESCRIPTION OF SYMBOLS 1 Support stand 2 Shielding layer 3 Support substrate 4 Thin film sample 4a Pattern 5 Transmission window 6, 9, 106 Reference light hole 6a, 6b Open shape 6c Overlapping area 7 Vertical through-hole 8 Shielding thin film 10, 20, 110 Sample structure 11 Imaging panel 12 Incident X-rays 12a, 12b Diffracted light 12a 'Object light 12b' Reference light 51 Focused ion beam 52 Ion beam 53 Reactive gas

Claims (5)

A support substrate having an upper surface and a lower surface as main surfaces and transmitting X-rays;
A shielding layer for shielding the X-rays formed on the lower surface of the support substrate;
. A transmission window that penetrates the shielding layer and exposes the support substrate on the bottom surface;
A thin film sample formed on the upper surface of the support substrate;
Reference light, which is established in a region within the coherence length of the X-rays incident on the transmission window, penetrates the shielding layer, the support substrate, and the thin film sample obliquely with respect to the main surface and allows reference light to pass therethrough. A hole, and
A sample structure for imaging an X-ray hologram in which openings above and below the reference light hole partially overlap when viewed from the direction perpendicular to the main surface of the support substrate. A support substrate having an upper surface and a lower surface as main surfaces and transmitting X-rays;
A shielding layer for shielding the X-rays formed on the lower surface of the support substrate;
. A transmission window formed through the shielding layer and exposing the support substrate on the bottom surface;
A thin film sample formed on the upper surface of the support substrate;
A vertical through hole that is established in a region within the coherence length of the X-rays incident on the transmission window and penetrates the shielding layer and the support substrate perpendicularly to the main surface;
A shielding thin film made of an X-ray shielding material that is thinner than the shielding layer covering the vertical through-hole and extending on the supporting substrate or the shielding layer in the vicinity thereof so as to close the opening of the vertical through-hole,
A reference light hole that passes through the shielding thin film and allows the reference light to pass through;
A sample structure for imaging an X-ray hologram. The thin film sample is formed on the upper surface of the support substrate, directly above the transmission window,
The reference light hole is formed through the shielding layer and the support substrate.
The sample structure for imaging an X-ray hologram according to claim 1. The thin film sample is formed on the upper surface of the support substrate, directly above the transmission window,
The vertical through hole is formed through the shielding layer and the support substrate.
The sample structure for imaging an X-ray hologram according to claim 2. Forming a thin film sample for measurement on an upper surface of a support substrate having an upper surface and a lower surface as main surfaces;
Next, removing the lower surface of the support substrate and reducing the thickness of the support substrate to a thickness that allows X-rays to pass through;
Next, forming a shielding layer that shields the X-rays on the lower surface of the support substrate;
A process of opening a transmission window that penetrates the shielding layer and exposes the support substrate on the bottom surface;
Vertical penetration that penetrates the shielding layer, the support substrate, and the thin film sample into a region within the coherence length of the X-ray incident on the lower surface of the shielding layer by vertically irradiating a focused ion beam to the transmission window. Opening a hole;
Next, a material gas is supplied onto the thin film sample or the shielding layer, and the opening of the vertical through hole is covered using a chemical vapor deposition method in which an electron beam or an ion beam is irradiated in the vicinity of the vertical through hole. Forming a shielding thin film made of an X-ray shielding material thinner than the shielding layer extending around the thin film sample or the shielding layer in the vicinity thereof;
Next, irradiating a focused ion beam perpendicularly to the shielding thin film to form a reference light hole that penetrates the shielding thin film and allows a reference light to pass through;
A method for manufacturing a sample structure for imaging an X-ray hologram.