JP2012127685A - Metal grid manufacturing method, metal grid, and x-ray imaging apparatus using metal grid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal grid manufacturing method capable of more accurately forming metal parts of a grid by electroforming using a silicon (Si) substrate, and to provide the metal grid and an X-ray imaging apparatus using the metal grid.SOLUTION: A metal grid DG includes a first Si layer 11 and a grid 12 formed on the first Si layer 11 and configured by alternately arraying second Si parts 12a and metal parts 12b in parallel with each other. Each second Si part 12a has a first insulating layer 12c between itself and the first Si layer 11 and has a second insulating layer 12d between itself and the metal part 12b. The metal grid DG is manufactured by forming resist layers on second Si layers of a substrate including the second Si layers attached to the first Si layer 11 through the first insulating layers 12c, patterning and removing the resist layers by a lithographic method, etching the second Si layers corresponding to the removed portions until arrival at the first Si layer 11 by a dray etching method to form slit grooves, forming second insulating layers on the side faces of the slit grooves by an anodic oxidation method, and filling the slit grooves with a metal by the electroforming method.

Description

  The present invention relates to a method for manufacturing a metal grid for manufacturing a grid that can be suitably used for, for example, a Talbot interferometer or a Talbot-Lau interferometer, and the metal grid. The present invention relates to an X-ray imaging apparatus using this metal grid.

  Diffraction gratings are used in optical systems of various devices as spectroscopic elements having a large number of parallel periodic structures, and in recent years, application to X-ray imaging devices has also been attempted. The diffraction gratings are classified into transmission diffraction gratings and reflection diffraction gratings when classified by the diffraction method. Furthermore, the transmission diffraction gratings periodically arrange light absorbing portions on a substrate that transmits light. There are an amplitude type diffraction grating (absorption type diffraction grating) and a phase type diffraction grating in which portions for changing the phase of light are periodically arranged on a substrate that transmits light. Here, absorption means that more than 50% of light is absorbed by the diffraction grating, and transmission means that more than 50% of light passes through the diffraction grating.

  Near-infrared, visible or ultraviolet diffraction gratings can be manufactured relatively easily because near-infrared, visible and ultraviolet light is sufficiently absorbed by very thin metals. For example, a metal is deposited on a substrate such as glass to form a metal film on the substrate, and the metal film is patterned into a grating, whereby an amplitude diffraction grating using a metal grating is manufactured. In the amplitude type diffraction grating for visible light, when aluminum (Al) is used as the metal, the transmittance for visible light (about 400 nm to about 800 nm) in aluminum is 0.001% or less. A thickness of about 100 nm is sufficient.

  On the other hand, as is well known, X-rays generally have very little absorption by substances, and the phase change is not so great. Even when a diffraction grating for X-rays is manufactured with relatively good gold (Au), the thickness of the gold is required to be about 100 μm, and the transmission part and the absorption or phase change part have an equal width of several μ to When the periodic structure is formed with a pitch of several tens of microns, the ratio of the thickness to the width of the gold portion (aspect ratio = thickness / width) is a high aspect ratio of 5 or more. It is not easy to manufacture such a high aspect ratio structure. Thus, for example, Patent Document 1 proposes a method of manufacturing a diffraction grating having such a high aspect ratio structure.

  The method for manufacturing a diffraction grating disclosed in Patent Document 1 is a method for manufacturing a diffraction grating used in an X-ray Talbot interferometer, and is configured to include the following steps. First, a metal sheet layer is formed on one side surface of a glass substrate. Next, an ultraviolet photosensitive resin is applied onto the metal sheet layer, and the ultraviolet photosensitive resin is subjected to pattern exposure using an optical lithography mask for a phase type diffraction grating and developed to be patterned. Next, an X-ray absorbing metal portion is formed in the portion where the ultraviolet photosensitive resin has been removed by metal plating. Then, the patterned ultraviolet photosensitive resin and the portion of the metal sheet layer corresponding to the ultraviolet photosensitive resin are removed. Thereby, a phase type diffraction grating is manufactured. Then, an ultraviolet photosensitive resin is applied to the one side surface of the phase type diffraction grating, and the ultraviolet photosensitive resin is subjected to pattern exposure from the other side surface of the phase type diffraction grating using the phase type diffraction grating as an optical lithography mask, It is patterned by being developed. Next, a voltage is applied through the metal sheet layer to further remove X-ray absorption into the X-ray absorbing metal portion of the phase type diffraction grating where the ultraviolet photosensitive resin is removed by metal plating. A metal part is formed. Hereinafter, each of the above steps is repeated until the thickness of the X-ray absorbing metal portion becomes a required thickness, using the phase diffraction grating in which the X-ray absorbing metal portion is further formed as a new optical lithography mask. Thereby, an amplitude type diffraction grating is manufactured.

JP 2009-37023 A

  By the way, in the method for manufacturing a diffraction grating disclosed in Patent Document 1, each process is repeated until the X-ray absorbing metal portion has a required thickness, which is troublesome and complicated.

  Therefore, it is conceivable to manufacture a diffraction grating using a metal grating by utilizing the characteristics of silicon that can form a three-dimensional structure with a high aspect ratio. That is, a slit groove having a periodic structure with a high aspect ratio is formed on a silicon substrate, and the diffraction grating is formed by filling the metal by electroplating (electroforming) by utilizing the conductivity of silicon in the formed slit groove. A manufacturing method is conceivable.

  However, in this method, since the entire silicon is conductive, the metal grows not only from the bottom of the slit groove, but also from the side surface of the slit groove, and as a result, inside the metal portion. There is a possibility that a space (void, a portion not filled with metal) may be generated, and it is difficult to densely fill the slit groove with the metal by electroforming.

  The present invention has been made in view of the above-described circumstances, and the object thereof is to provide a method for manufacturing a metal lattice that can form a metal portion of the lattice more densely by electroforming using a silicon substrate, and It is to provide a metal grid. Another object of the present invention is to provide an X-ray imaging apparatus using this metal grating.

  As a result of various studies, the present inventor has found that the above object is achieved by the present invention described below. That is, the method for manufacturing a metal lattice according to one aspect of the present invention includes the first silicon layer and the second silicon in the substrate including the second silicon layer attached to the first silicon layer via the first insulating layer. A resist layer forming step of forming a resist layer on a main surface of the layer, a patterning step of patterning the resist layer by a lithography method to remove the resist layer in the patterned portion, and a step of forming the resist layer by a dry etching method. The second silicon layer corresponding to the removed portion is etched until it reaches at least the first silicon layer to form a slit groove, and a voltage is applied to the second silicon layer by an anodic oxidation method. An insulating layer forming step of forming a second insulating layer on the surface of the slit groove and an electroforming method, the first The slit groove by applying a voltage to the silicon layer, characterized in that it comprises a step electroforming filled with metal.

  In the metal grating manufacturing method having such a configuration, since silicon is dry-etched, it is possible to form a slit groove having a high ratio of depth to width in the slit groove (aspect ratio of slit groove = depth / width). it can. As a result, the metal grating manufacturing method having such a configuration can manufacture a metal grating having a metal portion with a high aspect ratio by filling the slit groove with metal. Then, when the slit groove is filled with metal by electroforming in the electroforming step, first, a second insulating layer is formed on the surface of the slit groove by an anodic oxidation method in the insulating layer forming step. Therefore, in the electroforming process, the second insulating layer formed between the first insulating layer and the inner side surface of the slit groove between the first silicon layer and the second silicon layer, the second silicon layer is It is electrically insulated from one silicon layer. For this reason, metal does not precipitate and grow from the inner side surface (side surface of the second silicon layer) of the slit groove, and metal deposits and grows from the bottom of the slit groove (first silicon layer). Therefore, in the method for manufacturing a metal grid having such a configuration, since the metal is selectively grown from the bottom of the slit groove in this way, generation of voids can be effectively suppressed. As a result, the method for producing a metal grid having such a configuration can form the metal portion of the grid more densely by electroforming.

  In another aspect, in the above-described metal grating manufacturing method, the sum of the thickness of the first insulating layer and the thickness of the second silicon layer is a thickness corresponding to the depth of the slit groove. As described above, the method further includes an adjusting step of adjusting the thickness of the second silicon layer by a smart cut method.

  Since the thickness of the second silicon layer is adjusted by the smart cut method in the manufacturing method of the metal grid having such a configuration, the cut surface of the second silicon layer becomes flatter and the metal grid is formed with high accuracy. be able to.

  In another aspect, the dry etching method is RIE (Reactive Ion Etching) in the above-described metal lattice manufacturing method.

  In the method of manufacturing the metal grid having such a configuration, since the anisotropic etching can be performed by RIE, the second silicon layer can be etched along the depth direction (stacking direction), which is relatively easy. A slit groove can be formed.

  In another aspect, the dry etching method is a Bosch process in the above-described metal grating manufacturing method.

  In the manufacturing method of the metal grid having such a configuration, the second silicon layer is dry-etched by the Bosch process, so that the side surface of the slit groove becomes flat and the metal grid can be formed with high accuracy.

  According to another aspect, in the above-described method for manufacturing a metal lattice, the first silicon layer is the n-type silicon.

  In the manufacturing method of the metal grid having such a configuration, since the conductivity type of the first silicon layer is n-type, when the first silicon layer is used as a cathode by electroforming, the first silicon layer can be easily formed from the first silicon layer. Electrons can be given to the plating solution to deposit metal.

  According to another aspect, in the above-described method for manufacturing a metal lattice, the second silicon layer is p-type silicon.

  In the manufacturing method of the metal grid having such a structure, since the conductivity type of the second silicon layer is p-type, the slit groove can be easily formed when the second silicon layer is used as an anode by an anodic oxidation method. An oxide film can be formed on the side surface of the second silicon layer.

  In another aspect, the above-described metal grating manufacturing method is used when a metal grating used in an X-ray Talbot interferometer or an X-ray Talbot-low interferometer is manufactured.

  As described above, a high aspect ratio is required for X-rays, but an X-ray Talbot interferometer provided with a metal part having a high aspect ratio that is more densely formed by using these metal grating manufacturing methods described above. Alternatively, a diffraction grating used for an X-ray Talbot-Lau interferometer or a metal grating of a multi-slit plate can be manufactured.

  A metal lattice according to another aspect of the present invention includes a first silicon layer, a plurality of second silicon portions formed on the first silicon layer and extending linearly in one direction, and a line extending in the one direction. And a plurality of first insulating layers between the first silicon layer and the plurality of second silicon portions, respectively. A plurality of second insulating layers are further provided between the plurality of second silicon portions and the plurality of metal portions, respectively.

  By the above-described metal grid manufacturing method, a metal grid having such a configuration can be obtained, and the metal grid having such a configuration can include a metal portion having a high aspect ratio formed more densely. For this reason, the metal grating having such a configuration can be suitably used for, for example, X-rays, and can be particularly suitably used for an X-ray Talbot interferometer or an X-ray Talbot-Lau interferometer.

  An X-ray imaging apparatus according to another aspect of the present invention includes an X-ray source that emits X-rays, and a Talbot interferometer or a Talbot-low interferometer that is irradiated with X-rays emitted from the X-ray source. And an X-ray imaging device that captures an X-ray image by the Talbot interferometer or the Talbot-Lau interferometer, wherein the Talbot interferometer or Talbot-Lau interferometer includes the above-described metal grating, To do.

  In the X-ray imaging apparatus having such a configuration, the above-described metal grating having a denser metal portion is used for the metal grating constituting the Talbot interferometer or the Talbot-Lau interferometer. An X-ray image can be obtained.

  The method for producing a metal grid according to the present invention can form a metal portion of the grid more densely by electroforming using a silicon substrate. In the present invention, a metal grating manufactured by such a method of manufacturing a metal grating and an X-ray imaging apparatus using the metal grating are provided.

It is a perspective view which shows the structure of the metal lattice in embodiment. It is a figure (the 1) for demonstrating the manufacturing method of the metal grating | lattice in embodiment. It is FIG. (2) for demonstrating the manufacturing method of the metal grating | lattice in embodiment. It is FIG. (3) for demonstrating the manufacturing method of the metal grating | lattice in embodiment. It is a perspective view which shows the member in the manufacturing process of the metal grating | lattice in embodiment. It is a figure for demonstrating the manufacturing method of the silicon substrate used in order to manufacture the metal grating | lattice in embodiment. It is a perspective view which shows the structure of the Talbot interferometer for X-rays in embodiment. It is a top view which shows the structure of the Talbot low interferometer for X-rays in embodiment. It is explanatory drawing which shows the structure of the X-ray imaging device in embodiment.

  Hereinafter, an embodiment according to the present invention will be described with reference to the drawings. In addition, the structure which attached | subjected the same code | symbol in each figure shows that it is the same structure, The description is abbreviate | omitted suitably. Further, in this specification, when referring generically, it is indicated by a reference symbol without a suffix, and when referring to an individual configuration, it is indicated by a reference symbol with a suffix.

(Metal grid)
FIG. 1 is a perspective view showing a configuration of a metal grid in the embodiment. As shown in FIG. 1, the metal lattice DG of this embodiment includes a first silicon layer 11 and a lattice 12 formed on the first silicon layer 11. The first silicon portion 11 has a plate shape or a layer shape along the DxDy plane when a DxDyDz orthogonal coordinate system is set as shown in FIG. The lattice 12 has a plurality of second silicon portions 12a having a predetermined thickness H (including a first insulating layer 12c described later) and extending linearly in one direction Dx, and the predetermined thickness H (lattice plane). A plurality of metal portions 12b having a Dz direction perpendicular to DxDy (a length in the normal direction of the lattice plane DxDy) and extending linearly in the one direction Dx, and the plurality of second silicon portions 12a, The plurality of metal portions 12b are alternately arranged in parallel. For this reason, the plurality of metal portions 12b are respectively disposed at predetermined intervals in a direction Dy orthogonal to the one direction Dx. In other words, the plurality of second silicon layers 12a are respectively arranged at predetermined intervals in a direction Dy orthogonal to the one direction Dx. The predetermined interval (pitch) P is constant in this embodiment. That is, the plurality of metal portions 12b (the plurality of second silicon portions 12a) are arranged at equal intervals P in the direction Dy orthogonal to the one direction Dx. The second silicon portion 12a has a plate shape or a layer shape along the DxDz surface orthogonal to the DxDy surface, and the metal portion 12b also has a plate shape or a layer shape along the DxDz surface.

A plurality of first insulating layers 12c are further provided between the first silicon layer 11 and the plurality of second silicon portions 12a, respectively. The first insulating layer 12c functions to electrically insulate the first silicon layer 11 and the second silicon portion 12a, and is formed of, for example, an oxide film. Examples of the oxide film include a silicon oxide film (SiO ₂ film, silicon oxide film).

Furthermore, a plurality of second insulating layers 12d are further provided between the plurality of second silicon portions 12a and the plurality of metal portions 12b, respectively. That is, the second insulating layer 12d is formed on both side surfaces of the second silicon portion 12a. In other words, the second insulating layer 12d is formed on both side surfaces of the metal portion 12b. The second insulating layer 12d functions to electrically insulate the second silicon layer 12a and the metal portion 12b, and is formed of, for example, an oxide film. Examples of the oxide film include a silicon oxide film (SiO ₂ film).

  The first silicon layer 11, the plurality of second silicon portions 12a, the plurality of first insulating layers 12c, and the plurality of second insulating films 12d function to transmit X-rays, and the plurality of metal portions 12b Functions to absorb lines. Therefore, as an aspect, the metal grating DG functions as a diffraction grating by appropriately setting the predetermined interval P according to the wavelength of the X-ray. The metal of the metal portion 12b is preferably selected to absorb X-rays. For example, a metal or a noble metal having a relatively heavy atomic weight, more specifically, for example, gold (Au), platinum (platinum, Pt ), Rhodium (Rh), ruthenium (Ru) and iridium (Ir). Further, the metal portion 12b has an appropriate thickness H so that, for example, X-rays can be sufficiently absorbed according to specifications. As a result, the ratio of the thickness H to the width W in the metal portion 12b (aspect ratio = thickness / width) is, for example, a high aspect ratio of 5 or more. The width W of the metal portion 12b is the length of the metal portion 12b in the direction (width direction) Dy orthogonal to the one direction (long direction) Dx, and the thickness H of the metal portion 12b is equal to the one direction Dx. This is the length of the metal portion 12b in the normal direction (depth direction) Dz of the plane DxDy constituted by the direction Dy perpendicular to this.

  An insulating layer may be present on the upper surface (on the surface, the top surface) of the second silicon portion 12a. In the example shown in FIG. 1, this insulating layer is obtained by extending the second insulating layer 12 d.

  The metal lattice DG including the high-aspect-ratio metal portion 12b includes the first silicon layer and the second silicon layer on the substrate including the second silicon layer attached to the first silicon layer via the first insulating layer. A resist layer forming step for forming a resist layer on the main surface of the silicon layer, and etching the second silicon layer corresponding to a portion where the resist layer has been removed by a dry etching method until at least the first silicon layer is reached. An etching process for forming slit grooves, an anodizing method, an insulating layer forming process for applying a voltage to the second silicon layer to form a second insulating layer on the surface of the slit grooves, and an electroforming method. And an electroforming process in which a voltage is applied to the first silicon layer to fill the slit groove with metal. Hereinafter, the manufacturing method of this metal lattice DG is explained in full detail.

  2 to 4 are views for explaining a method of manufacturing a metal grid in the embodiment. FIG. 5 is a perspective view showing members in the manufacturing process of the metal grid in the embodiment. FIG. 6 is a diagram for explaining a method of manufacturing a silicon substrate used for manufacturing the metal grid in the embodiment.

  In order to manufacture the metal lattice DG of the present embodiment, first, a silicon substrate 30 including a first silicon layer 31 and a second silicon layer 32 attached to the first silicon layer 31 via a first insulating layer 33 is provided. Prepared (FIG. 2A).

  Here, preferably, the first silicon layer 31 is n-type silicon in which majority carriers are electrons. Since n-type silicon has abundant conductor electrons, when negative polarity is applied by connecting silicon to the cathode and cathode polarization is performed, in the electroforming process described later, a so-called ohmic contact with the plating solution 49 occurs. It tends to flow and cause a reduction reaction, and as a result, the metal is more likely to precipitate.

  Preferably, the second silicon layer 32 is p-type silicon in which majority carriers are holes. Since the majority carriers of p-type silicon are holes, in the insulating layer forming process described later, so-called ohmic contact is made with the anode of the power supply 44, and it becomes easy to anodize easily.

  Such a silicon substrate 30 is manufactured by the following steps as shown in FIG. 6, for example. First, a first silicon wafer 21 to be the first silicon layer 31 and a second silicon wafer 22 to be the second silicon layer 32 are prepared, and one main surface of the first and second silicon wafers 21 and 22, for example, Then, an insulating layer 23 is formed on one main surface of the second silicon wafer 22 (FIG. 6A).

  The first and second silicon wafers 21 and 22 may have the same electrical characteristics or may be different. For example, the resistivity of the first and second silicon wafers 21 and 22 may be the same or different. Further, for example, the first and second silicon wafers 21 and 22 may have the same or different conductivity types. In the present embodiment, the first silicon wafer 21 is a relatively low-resistance n-type silicon substrate manufactured by, for example, the CZ (Czochralski) method, for example, doped with phosphorus or the like (for example, the resistivity is 10 Ωcm (ohm centimeter). ), 1 Ωcm (ohm centimeter), 0.1 Ωcm (ohm centimeter), etc.). The second silicon wafer 22 is also produced by the CZ method in the same manner as the first silicon wafer 21 and is a relatively high resistance p-type silicon substrate doped with, for example, boron (for example, a resistivity of 10 Ωcm,... 0.1Ωcm).

  The insulating layer 23 is a layer that becomes the first insulating layer 33, and is, for example, the silicon oxide film 23. The silicon oxide film 23 is formed by, for example, a thermal oxidation method in which the second silicon wafer 22 is heated at a high temperature in an oxygen atmosphere or a gas atmosphere containing water vapor. Note that the method for forming the oxide film is not limited to this, and other known methods can also be used. The silicon oxide film 23 may be formed by, for example, a gas phase reaction method in which monosilane reacts with oxygen or the like. Comparing the thermal oxidation method and the gas phase reaction method, the thermal oxidation method can control the thickness of the silicon oxide film 23 to be formed relatively accurately, and can be a stable silicon oxide film 23 with few impurities. This is superior to the gas phase reaction method.

Next, in order to adjust the sum H of the thickness of the insulating layer 23 as the first insulating layer 33 and the thickness of the second silicon wafer 22 by the Smart Cut method, the second silicon is interposed through the insulating layer 23. Hydrogen ions H ⁺ are implanted from one main surface of the wafer 22 (FIG. 6B).

The smart cut method is a method of cutting a silicon thin film by partially cutting a silicon crystal lattice by implanting hydrogen ions H ⁺ into a silicon single crystal. In this smart cut method, first, the second silicon wafer 22 including the insulating layer 23 can be cut to a desired thickness H so that a depth corresponding to the desired thickness H is set at a predetermined concentration. Hydrogen ions H ⁺ are implanted. The depth of the hydrogen ions H ⁺ are injected is controlled by adjusting the hydrogen ion H ⁺ implantation energy. Next, as will be described later, the second silicon wafer 22 is heat-treated at a predetermined temperature, whereby the second silicon wafer 22 is cut out at the depth position where the hydrogen ions H ⁺ are implanted.

Here, as described later, in the manufacturing method of the metal lattice DG in the present embodiment, the metal is filled in the slit groove SD formed by etching the second silicon wafer 22 by electroforming (electroplating). Since the metal portion 12b is formed, the thickness H of the second silicon wafer 22 including the insulating layer 23 becomes the thickness H of the metal portion 12b. For this reason, the thickness H of the second silicon wafer 22 including the insulating layer 23 is determined according to the thickness H of the metal portion 12b. Then, the smart cut method, since the second silicon wafer 22 is cut by the depth position implanting hydrogen ions H ^+, the depth of implanting hydrogen ions H ^+, the thickness of the insulating layer 23 and the second It is determined according to the sum H of the thickness of the silicon wafer 22, ie, the thickness H of the metal portion 12b.

  Next, the bonding surfaces of the first silicon wafer 21 and the insulating layer 23 are cleaned with a predetermined cleaning liquid 24 (FIG. 6C). Examples of the cleaning liquid 24 include RCA cleaning liquid, ultrapure water, deionized water, hydrofluoric acid, and the like. After cleaning, the two first silicon wafers 21 and the second silicon wafer 22 are dried.

  Next, the first silicon wafer 21 and the second silicon wafer 22 are brought into contact with each other through the insulating layer 23 and are brought into close contact with each other (FIG. 6D). These operations are performed in a clean room in order to prevent dust from adhering to the contact surfaces of the first silicon wafer 21 and the insulating layer 23.

Next, the first silicon wafer 21 and the second silicon wafer 22 combined with each other through the insulating layer 23 are heat-treated at a predetermined temperature. Thereby, the first silicon wafer 21 and the second silicon wafer 22 are bonded to each other by wafer bonding at the bonding surfaces of the first silicon wafer 21 and the insulating layer 23 and attached to each other, and the depth in which the hydrogen ions H ⁺ are implanted is described above. The second silicon wafer 22 is peeled from the position (FIG. 6E). The first silicon wafer 21 becomes the first silicon layer 31, the cut out portion of the second silicon wafer 22 becomes the second silicon layer 32, and the insulating layer 23 becomes the first insulating layer 33. The surface of the second silicon layer 32 formed by peeling off may be smoothed by polishing or the like.

  Thus, the silicon substrate 30 in which the second silicon layer 32 is attached to the first silicon layer 31 through the first insulating layer 33 is manufactured.

Here, in the above description, the thickness H of the second silicon wafer 22 including the insulating layer 23 (the second silicon layer 32 including the first insulating layer 33) is adjusted by the smart cut method, but the present invention is not limited thereto. It is not a thing and a well-known means can be used. For example, the second silicon wafer 22 may be polished to adjust the thickness H of the second silicon wafer 22 including the insulating layer 23 (second silicon layer 32 including the first insulating layer 33). In this case, it is not necessary to perform the aforementioned hydrogen ion H ⁺ implantation step.

  In the above description, the first silicon wafer 21 and the second silicon wafer 22 are bonded via the insulating layer 23 by wafer bonding. However, the present invention is not limited to this, and known means can be used. For example, the first silicon wafer 21 and the second silicon wafer 22 may be bonded via the insulating layer 23 by plasma bonding.

  And the manufacturing method which manufactures such a silicon substrate 30 is not limited to the above-mentioned method demonstrated using FIG. For example, oxygen ions may be implanted into a low resistance CZ substrate from one main surface thereof, and an insulating layer may be formed at a depth position separated from the main surface by a certain distance. Further, for example, an insulating layer (first insulating layer 33) is formed on the first low resistance CZ substrate (first silicon layer 31), and then the second silicon (second silicon layer 32) is formed to a desired thickness. Epitaxial growth may be performed by (the sum H of the thickness of the first insulating layer 33 and the thickness of the second silicon layer 32).

  Returning to FIG. 2, a photosensitive resin layer (resist layer) 41 is formed on the main surface of the second silicon layer 32 in the silicon substrate 30 by, for example, spin coating (resist formation step, FIG. 2B). Here, the resist layer is a material that is used in lithography and whose physical properties such as solubility are changed by light (including not only visible light but also ultraviolet rays), an electron beam, and the like. In this embodiment, the case where it is the photosensitive resin layer is demonstrated as the example, However It is not limited to this, For example, the resist layer may be a resist layer for electron beam exposure.

  Next, as a photolithography process, the photosensitive resin layer 41 is patterned by a lithography method (FIG. 2C), and the patterned photosensitive resin layer 41 is removed (patterning process, FIG. 3A). ). More specifically, the lithography mask 42 is pressed against the photosensitive resin layer 41, the ultraviolet ray 43 is irradiated to the photosensitive resin layer 41 through the lithography mask 42, and the photosensitive resin layer 41 is subjected to pattern exposure and development. (FIG. 2C). And the photosensitive resin layer 41 of the part which was not exposed (or exposed part) is removed (FIG. 3 (A)).

  Next, the second silicon layer 32 corresponding to the portion from which the photosensitive resin layer 41 has been removed by dry etching is etched until at least the first silicon layer 31 is reached in the normal direction Dz. That is, the first insulating layer 33 is also etched by this step. As a result, a slit groove SD is formed (etching process, FIGS. 3B and 5). More specifically, using the patterned photosensitive resin layer 41 as a mask, ICP is performed until at least the first silicon layer 31 is exposed through the first insulating layer 33 from the surface of the second silicon layer 32 in the silicon substrate 30. (Inductively Coupled Plasma) The second silicon layer 32 and the first insulating layer 33 are etched by dry etching. If the photosensitive resin layer 41 alone is not sufficient to carve out the second silicon layer 32 and the first insulating layer 33 having a desired thickness H, aluminum, for example, is formed on the silicon substrate 30. (Al), quartz (Si) or the like is formed, the photosensitive resin layer 41 is formed on the aluminum film or the quartz film, and after patterning the photosensitive resin layer 41 by lithography as described above, Using the patterned photosensitive resin layer 41 as a mask, an aluminum film or a quartz film is patterned, and using the patterned aluminum film or the quartz film as a mask, the second silicon layer 32 and the first insulating layer 33 are used as described above. ICP dry etching may be used.

This ICP dry etching is preferably an ASE process using an ICP apparatus because it enables vertical etching with a high aspect ratio. This ASE (Advanced Silicon Etch) process is a process of etching a silicon substrate by RIE (reactive ion etching) using F radicals and F ions in SF ₆ plasma, CF _x radicals in C ₄ F ₈ plasma, and A process of depositing a polymer film having a composition close to Teflon (registered trademark) on the wall surface and acting as a protective film by a polymerization reaction of these ions is repeatedly performed. In addition, since more vertical etching can be performed at a high aspect ratio, it is more preferable to repeat a state in which the SF ₆ plasma is rich and a state in which the C ₄ F ₈ plasma is rich as in the Bosch process. Thus, the side wall protection and the bottom surface etching may be alternately performed. The dry etching method is not limited to ICP dry etching, and other methods may be used. For example, so-called parallel plate type reactive ion etching (RIE), magnetic neutral line plasma (NLD) dry etching, chemical assisted ion beam (CAIB) etching, electron cyclotron resonance type reactive ion beam (ECRIB) etching, etc. It may be technology.

  The plate-like body of the second silicon layer 32 left after the etching becomes the second silicon portion 12a, and the first insulating layer 33 left after the etching becomes the first insulating layer 12c in the metal lattice DG.

  FIG. 5 shows an example of the structure of the member after the etching process, and FIG. 3B shows the member in the manufacturing process as an example, taken along the line AA ′ shown in FIG. A cross section of this member is shown.

  Next, the second insulating layer 34 is formed on at least the inner surface of the slit groove SD (insulating layer forming step, FIG. 3C). For example, a voltage is applied to the second silicon layer 32 by an anodic oxidation method to form an oxide film as the second insulating layer 34 on at least the inner surface of the slit groove SD. More specifically, as shown in FIG. 4A, the anode of the power source 44 is connected to the second silicon layer 32 as the plurality of silicon portions 12a, and the cathode electrode 45 and silicon connected to the cathode of the power source 44 The substrate 30 is immersed in the electrolytic solution 46. In FIG. 4A, although it seems that a voltage is applied only to the leftmost second silicon layer 32 in the drawing, each second silicon layer 32 shown in FIG. As shown in the drawing, at least one end (both ends in the example shown in FIG. 5) is connected to each other, so that a voltage is applied to the entire second silicon layer 32 shown in FIG. 4 (A). Note that the example shown in FIG. 5 is an example of one structure, and may have another structure. The electrolytic solution 46 is preferably an acidic solution that has a strong oxidizing power and does not dissolve the oxide film produced by anodic oxidation, such as a solution of nitric acid, hydrochloric acid, sulfuric acid, oxalic acid, phosphoric acid, and the like. The cathode electrode 45 is preferably formed of a metal that does not dissolve in the electrolytic solution 46, such as gold (Au) and platinum (Pt). With such a configuration, the surface of the second silicon layer 32 in contact with the electrolytic solution 46 is oxidized by anodic oxidation. In this example, the bottom surface of the slit groove SD (the portion where the first silicon layer 31 faces the slit groove) is not oxidized, and both side surfaces (inner side surfaces of the slit groove SD) and the upper surface of the second silicon layer 32 are oxidized. The second silicon layer 32 is covered with a silicon oxide film. The thickness of the silicon oxide film is generally proportional to the voltage and energization time. The silicon oxide film functions to cut off the voltage applied to the second silicon layer 32 in the next electroforming process (function to electrically insulate the second silicon layer 32), so that the silicon oxide film is thick enough to perform the function. For example, it may be about 10 nm or more. For example, when anodization is performed by immersing silicon in nitric acid having a concentration of 68% and applying a voltage of 20 V for 10 minutes, an oxide film of about 10 nm is formed.

  Next, a voltage is applied to the first silicon layer 31 by electroforming (electroplating) to fill the slit groove SD with metal (electroforming process, FIG. 4B). More specifically, the cathode of the power supply 47 is connected to the first silicon layer 31, and the anode electrode 48 and the silicon substrate 30 connected to the anode of the power supply 47 are immersed in the plating solution 49. As a result, metal is deposited and grown from the first silicon layer 31 side at the bottom of the slit groove SD by electroforming. When this metal fills the slit groove SD, the electroforming is finished. As a result, the metal grows by the same thickness H as the second silicon layer 32 including the first insulating layer 33. In this way, the slit groove SD is filled with metal, and the metal portion 12b is formed. This metal is preferably selected to absorb X-rays. For example, a metal or a noble metal having a relatively heavy atomic weight, more specifically, for example, gold (Au), platinum (platinum, Pt), rhodium. (Rh), ruthenium (Ru), iridium (Ir), indium (In), nickel (Ni) and the like.

  Through such manufacturing steps, the metal grid DG having the configuration shown in FIG. 1 is manufactured.

  In such a method of manufacturing the metal lattice DG, since the silicon substrate 30 is dry-etched, a slit having a high ratio of the depth H to the width W in the slit groove SD (aspect ratio of the slit groove SD = depth H / width W) is high. Grooves can be formed. As a result, such a method of manufacturing the metal lattice DG can manufacture the metal lattice DG having the high aspect ratio metal portion 12b by filling the slit groove SD with the high aspect ratio with metal. Then, when the slit groove SD is filled with metal by electroforming in the electroforming process, first, the second surface is measured on the surface of the slit groove SD without being formed on the bottom of the slit groove SD by the anodic oxidation method in the insulating layer forming process. An insulating layer 34 is formed. Therefore, in the electroforming process, the second insulating layer 34 formed between the first insulating layer 33 and the slit groove SD between the first silicon layer 31 and the second silicon layer 32 has the second effect. The silicon layer 32 is electrically insulated from the first silicon layer 31. For this reason, the metal does not precipitate and grow from the inner side surface (side surface of the second silicon layer 32) of the slit groove SD, and the metal precipitates and grows from the bottom (first silicon layer 31) of the slit groove SD. Therefore, in the manufacturing method of the metal lattice DG having such a configuration, since the metal is selectively grown from the bottom of the slit groove SD in this way, generation of voids can be effectively suppressed. As a result, the manufacturing method of the metal lattice DG having such a configuration can form the metal portions of the lattice more densely by electroforming. In particular, the diffraction grating used in the X-ray Talbot interferometer and the X-ray Talbot-low interferometer requires a high aspect ratio of the metal portion 12b, but the manufacturing method of the metal grating DG in this embodiment is as described above. It is possible to cope with such a high aspect ratio, for example, 5 times or more, preferably 10 times or more, more preferably 20 times or more, and can form a denser metal portion 12b, and X-ray Talbot interference It is suitable as a method for manufacturing a diffraction grating used in a X-ray Talbot-Lau interferometer.

  A slit groove having a high aspect ratio is formed on a silicon wafer by dry etching, a metal layer is formed on the bottom of the slit groove by sputtering or vacuum deposition, and the slit is formed by electroforming using the metal layer as an electrode. A method of manufacturing a metal grid that fills the groove with metal is also conceivable. However, in this manufacturing method, when the metal layer is formed by sputtering or vacuum deposition, the metal layer is not necessarily formed only at the bottom of the slit groove, and a good metal layer is formed at the bottom of the slit groove. Is not necessarily formed. It is very difficult to form a metal layer only at the bottom of the slit groove having a high aspect ratio. Such a point can also be eliminated in the method of manufacturing the metal grid DG in the present embodiment.

  Moreover, since the thickness H of the second silicon layer 32 is adjusted by the smart cut method in the manufacturing method of the metal lattice DG in the present embodiment, the cut surface of the second silicon layer 32 becomes flatter. A highly accurate metal lattice DG can be formed. In particular, when the metal grating DG functions as a diffraction grating, the entrance surface or the exit surface is more flat, which is preferable.

  Further, since the manufacturing method of the metal lattice DG in the present embodiment uses RIE (Reactive Ion Etching) in the etching process, so-called anisotropic etching can be performed. ), The second silicon layer 32 can be etched, and the slit groove SD can be formed relatively easily.

  Further, in the manufacturing method of the metal lattice DG in the present embodiment, since the second silicon layer 32 is dry etched by the Bosch process, the side surface of the slit groove SD becomes flat, and as a result, a highly accurate metal lattice DG is formed. can do. In particular, when the metal grating DG functions as a diffraction grating, the entrance surface or the exit surface is more flat, which is preferable.

  Here, although the oxide film 34 is also formed on the upper surface portion of the second silicon layer 32, even when the oxide film 34 is not formed on the upper surface portion of the second silicon layer 32, the second silicon layer 32 Since it is insulated by the first insulating layer 33, no metal is deposited on the upper surface portion of the second silicon layer 32 in the electroforming process.

  In the above-described embodiment, the diffraction grating DG has a one-dimensional periodic structure, but is not limited to this. The diffraction grating DG may be, for example, a two-dimensional periodic structure diffraction grating. For example, the diffraction grating DG having a two-dimensional periodic structure is configured such that dots serving as diffraction members are arranged at equal intervals with a predetermined interval in two linearly independent directions. A diffraction grating having such a two-dimensional periodic structure has a high-aspect-ratio hole formed in a plane with a two-dimensional period, and the hole is filled with a metal as described above, or a high-aspect-ratio cylinder is formed in a plane in two dimensions. It can be formed by standing up with a period and filling the periphery with metal in the same manner as described above.

(Talbot interferometer and Talbot low interferometer)
Since the metal grating DG of the above embodiment can form a metal portion with a high aspect ratio, it can be suitably used for an X-ray Talbot interferometer and a Talbot-low interferometer. An X-ray Talbot interferometer and an X-ray Talbot-low interferometer using the metal grating DG will be described.

  FIG. 7 is a perspective view showing a configuration of an X-ray Talbot interferometer in the embodiment. FIG. 8 is a top view showing the configuration of the X-ray Talbot-Lau interferometer in the embodiment.

  As shown in FIG. 7, an X-ray Talbot interferometer 100A according to the embodiment includes an X-ray source 101 that emits X-rays having a predetermined wavelength, and a phase type that diffracts X-rays emitted from the X-ray source 101. The first and second diffraction gratings 102 and 103 include a first diffraction grating 102 and an amplitude-type second diffraction grating 103 that forms an image contrast by diffracting the X-rays diffracted by the first diffraction grating 102. Are set to the conditions constituting the X-ray Talbot interferometer. Then, the X-ray with the image contrast generated by the second diffraction grating 103 is detected by, for example, an X-ray image detector 105 that detects the X-ray. In the X-ray Talbot interferometer 100A, at least one of the first diffraction grating 102 and the second diffraction grating 103 is the metal grating DG.

The conditions constituting the Talbot interferometer 100A are expressed by the following equations 1 and 2. Equation 2 assumes that the first diffraction grating 102 is a phase type diffraction grating.
l = λ / (a / (L + Z1 + Z2)) (Formula 1)
Z1 = (m + 1/2) × (d ² / λ) (Formula 2)
Here, l is the coherence distance, λ is the wavelength of X-rays (usually the center wavelength), and a is the aperture diameter of the X-ray source 101 in the direction substantially perpendicular to the diffraction member of the diffraction grating. Yes, L is the distance from the X-ray source 101 to the first diffraction grating 102, Z 1 is the distance from the first diffraction grating 102 to the second diffraction grating 103, and Z 2 is from the second diffraction grating 103. The distance to the X-ray image detector 105, m is an integer, and d is the period of the diffraction member (the period of the diffraction grating, the grating constant, the distance between the centers of adjacent diffraction members, the pitch P). .

  In the X-ray Talbot interferometer 100A having such a configuration, X-rays are irradiated from the X-ray source 101 toward the first diffraction grating 102. This irradiated X-ray produces a Talbot effect at the first diffraction grating 102 to form a Talbot image. This Talbot image is acted on by the second diffraction grating 103 to form an image contrast of moire fringes. Then, this image contrast is detected by the X-ray image detector 105.

  The Talbot effect means that when light enters the diffraction grating, the same image as the diffraction grating (self-image of the diffraction grating) is formed at a certain distance. Good, this self-image is called the Talbot image. When the diffraction grating is a phase type diffraction grating, the Talbot distance L is Z1 represented by the above formula 2 (L = Z1). In the Talbot image, an inverted image appears at an odd multiple of L (= (2m + 1) L, m is an integer), and a normal image appears at an even multiple of L (= 2 mL).

  Here, when the subject S is arranged between the X-ray source 101 and the first diffraction grating 102, the moire fringes are modulated by the subject S, and the modulation amount is caused by the refraction effect by the subject S. It is proportional to the angle at which the X-ray is bent. For this reason, the subject S and its internal structure are detected by analyzing the moire fringes.

  In the Talbot interferometer 100A configured as shown in FIG. 7, the X-ray source 101 is a single point light source, and such a single point light source forms a single slit (single slit). The X-ray radiated from the X-ray source 101 passes through the single slit of the single slit plate and is directed toward the first diffraction grating 102 via the subject S. Is emitted. The slit is an elongated rectangular opening extending in one direction.

  On the other hand, the Talbot-Lau interferometer 100B includes an X-ray source 101, a multi-slit plate 104, a first diffraction grating 102, and a second diffraction grating 103, as shown in FIG. That is, the Talbot-Lau interferometer 100B further includes a multi-slit plate 104 having a plurality of slits formed in parallel on the X-ray emission side of the X-ray source 101 in addition to the Talbot interferometer 100A shown in FIG. Is done.

  The multi slit plate 104 may be a grating manufactured by the method for manufacturing the metal grating DG in the above-described embodiment. By manufacturing the multi-slit plate 104 by the method for manufacturing the metal lattice DG in the above-described embodiment, X-rays are transmitted through the slits (the plurality of second silicon portions 12a) and more reliably the plurality of metal portions 12b. Therefore, transmission and non-transmission of X-rays can be more clearly distinguished, so that a multi-light source can be obtained more reliably.

  By using the Talbot-Lau interferometer 100B, the X-ray dose radiated toward the first diffraction grating 102 via the subject S is increased compared to the Talbot interferometer 100A, so that a better moire fringe can be obtained. It is done.

  An example of the first diffraction grating 102, the second diffraction grating 103, and the multi-slit plate 104 used in the Talbot interferometer 100A or the Talbot-low interferometer 100B is as follows. In these examples, the second silicon portion 12a and the metal portion 12b are formed to have the same width, and the metal portion 12b is formed of gold.

  As an example, the distance R1 from the X-ray source 101 or the multi-slit plate 104 to the first diffraction grating 102 is 2 m, and the distance R2 from the X-ray source 101 or the multi-slit plate 104 to the first diffraction grating 102 is 2. In the case of 5 m, the first diffraction grating 102 has a pitch P of 5 μm, the metal portion 12 b has a thickness of 3 μm, the second diffraction grating 103 has a pitch P of 6 μm, and the metal The thickness of the portion 12b is 100 μm (aspect ratio = 100/3), and the multi-slit plate 104 has a pitch P of 30 μm and a thickness of the metal portion 12b of 100 μm.

  As another example, the distance R1 from the X-ray source 101 or the multi-slit plate 104 to the first diffraction grating 102 is 1.8 m, and the X-ray source 101 or the multi-slit plate 104 to the first diffraction grating 102 When the distance R2 is 2.5 m, the pitch P of the first diffraction grating 102 is 7 μm, the thickness of the metal portion 12b is 3 μm, and the pitch P of the second diffraction grating 103 is 10 μm, the thickness of the metal portion 12 b is 100 μm (aspect ratio = 100/5), and the multi-slit plate 104 has a pitch P of 20 μm and a thickness of the metal portion 12 b of 100 μm. is there.

(X-ray imaging device)
The metal grating DG can be used in various optical devices. However, since the metal portion 12b can be formed with a high aspect ratio, the metal grating DG can be suitably used for an X-ray imaging device, for example. In particular, an X-ray imaging apparatus using an X-ray Talbot interferometer treats X-rays as waves and detects a phase shift of the X-rays caused by passing through the subject to obtain a phase contrast method for obtaining a transmission image of the subject. Compared with the absorption contrast method that obtains an image in which the magnitude of X-ray absorption by the subject is a contrast, an improvement in sensitivity of about 1000 times is expected, so that the X-ray irradiation dose is, for example, 1/100 to 1 / 1000 has the advantage that it can be reduced. In the present embodiment, an X-ray imaging apparatus provided with an X-ray Talbot interferometer using the diffraction grating DG will be described.

  FIG. 9 is an explanatory diagram illustrating a configuration of the X-ray imaging apparatus according to the embodiment. In FIG. 9, an X-ray imaging apparatus 200 includes an X-ray imaging unit 201, a second diffraction grating 202, a first diffraction grating 203, and an X-ray source 204, and in this embodiment, an X-ray source. An X-ray power supply unit 205 that supplies power to 204, a camera control unit 206 that controls the imaging operation of the X-ray imaging unit 201, a processing unit 207 that controls the overall operation of the X-ray imaging apparatus 200, and an X-ray power supply And an X-ray control unit 208 that controls the X-ray emission operation in the X-ray source 204 by controlling the power supply operation of the unit 205.

  The X-ray source 204 is a device that emits X-rays by being supplied with power from the X-ray power supply unit 205 and emits X-rays toward the first diffraction grating 203. The X-ray source 204 emits X-rays when, for example, a high voltage supplied from the X-ray power supply unit 205 is applied between the cathode and the anode, and electrons emitted from the cathode filament collide with the anode. Device.

  The first diffraction grating 203 is a transmission type diffraction grating that generates a Talbot effect by X-rays emitted from the X-ray source 204. The first diffraction grating 203 is, for example, a diffraction grating manufactured by the method for manufacturing the metal grating DG in the above-described embodiment. The first diffraction grating 203 is configured so as to satisfy the conditions for causing the Talbot effect, and is a grating sufficiently coarser than the wavelength of X-rays emitted from the X-ray source 204, for example, a grating constant (period of the diffraction grating). d is a phase type diffraction grating in which the wavelength of the X-ray is about 20 or more. The first diffraction grating 203 may be such an amplitude type diffraction grating.

  The second diffraction grating 202 is a transmission-type amplitude diffraction grating that is disposed at a position that is approximately a Talbot distance L away from the first diffraction grating 203 and that diffracts the X-rays diffracted by the first diffraction grating 203. Similarly to the first diffraction grating 203, the second diffraction grating 202 is also a diffraction grating manufactured by the method for manufacturing the metal grating DG in the above-described embodiment, for example.

  These first and second diffraction gratings 203 and 202 are set to conditions that constitute the Talbot interferometer represented by the above-described Expression 1 and Expression 2.

  The X-ray imaging unit 201 is an apparatus that captures an X-ray image diffracted by the second diffraction grating 202. The X-ray imaging unit 201 includes, for example, a flat panel detector (FPD) including a two-dimensional image sensor in which a thin film layer including a scintillator that absorbs X-ray energy and emits fluorescence is formed on a light receiving surface, and incident photons. An image intensifier unit that converts the electrons into electrons on the photocathode, doubles the electrons on the microchannel plate, and causes the doubled electrons to collide with phosphors to emit light, and the output light of the image intensifier unit An image intensifier camera including a two-dimensional image sensor.

  The processing unit 207 is a device that controls the overall operation of the X-ray imaging apparatus 200 by controlling each unit of the X-ray imaging apparatus 200. For example, the processing unit 207 includes a microprocessor and its peripheral circuits. An image processing unit 271 and a system control unit 272 are provided.

  The system control unit 272 controls the X-ray emission operation in the X-ray source 204 via the X-ray power source unit 205 by transmitting and receiving control signals to and from the X-ray control unit 208, and the camera control unit 206 The imaging operation of the X-ray imaging unit 201 is controlled by transmitting and receiving control signals between the two. Under the control of the system control unit 272, X-rays are emitted toward the subject S, an image generated thereby is captured by the X-ray imaging unit 201, and an image signal is input to the processing unit 207 via the camera control unit 206. The

  The image processing unit 271 processes the image signal generated by the X-ray imaging unit 201 and generates an image of the subject S.

  Next, the operation of the X-ray imaging apparatus of this embodiment will be described. For example, the subject S is placed between the X-ray source 204 and the first diffraction grating 203 by placing the subject S on an imaging table including the X-ray source 204 inside (rear surface), and the X-ray imaging apparatus 200. When the user (operator) instructs the subject S to capture an image of the subject S from the operation unit (not shown), the system control unit 272 of the processing unit 207 controls the X-ray control unit 208 to irradiate X toward the subject S. Is output. In response to this control signal, the X-ray control unit 208 causes the X-ray power source unit 205 to supply power to the X-ray source 204, and the X-ray source 204 emits X-rays and irradiates the subject S with X-rays.

  The irradiated X-ray passes through the first diffraction grating 203 through the subject S, is diffracted by the first diffraction grating 203, and is a self-image of the first diffraction grating 203 at a position away from the Talbot distance L (= Z1). A Talbot image T is formed.

  The formed X-ray Talbot image T is diffracted by the second diffraction grating 202 to generate moire and form an image of moire fringes. This moire fringe image is captured by the X-ray imaging unit 201 whose exposure time is controlled by the system control unit 272, for example.

  The X-ray imaging unit 201 outputs an image signal of the moire fringe image to the processing unit 207 via the camera control unit 206. This image signal is processed by the image processing unit 271 of the processing unit 207.

  Here, since the subject S is disposed between the X-ray source 204 and the first diffraction grating 203, the phase of the X-ray that has passed through the subject S is shifted with respect to the X-ray that does not pass through the subject S. For this reason, the X-rays incident on the first diffraction grating 203 include distortion in the wavefront, and the Talbot image T is deformed accordingly. For this reason, the moire fringes of the image generated by the superposition of the Talbot image T and the second diffraction grating 202 are modulated by the subject S, and the X-rays are bent by the refraction effect by the subject S. Proportional to angle. Therefore, the subject S and its internal structure can be detected by analyzing the moire fringes. Further, by imaging the subject S from a plurality of angles, a tomographic image of the subject S can be formed by X-ray phase CT (computed tomography).

  Since the second diffraction grating 202 of the present embodiment is the metal grating DG in the above-described embodiment having the high-aspect-ratio metal portion 12b, good moire fringes can be obtained and a highly accurate image of the subject S can be obtained. can get.

  Further, since the thickness of the second silicon layer 32 is adjusted by the smart cut method in the metal grating DG, the cut surface of the second silicon layer 32 becomes flatter and the second diffraction grating 202 can be formed with high accuracy. Can do. For this reason, better moire fringes can be obtained, and a more accurate image of the subject S can be obtained.

  Further, since the second silicon layer 32 is dry etched by the Bosch process, the side surface of the slit groove SD becomes flatter and the second diffraction grating 202 can be formed with high accuracy. For this reason, better moire fringes can be obtained, and a more accurate image of the subject S can be obtained.

  In the X-ray imaging apparatus 200 described above, a Talbot interferometer is configured by the X-ray source 204, the first diffraction grating 203, and the second diffraction grating 202, but the X-ray source 204 has a multi-slit as a multi-slit. The Talbot-Lau interferometer may be configured by further arranging the metal grating DG in the above-described embodiment. By using such a Talbot-Lau interferometer, the X-ray dose irradiated to the subject S can be increased as compared with the case of a single slit, a better moire fringe can be obtained, and the subject S with higher accuracy can be obtained. An image is obtained.

  In the X-ray imaging apparatus 200 described above, the subject S is disposed between the X-ray source 204 and the first diffraction grating 203, but the subject S is disposed between the first diffraction grating 203 and the second diffraction grating 202. May be arranged.

  Further, in the above-described X-ray imaging apparatus 200, an X-ray image is captured by the X-ray imaging unit 201 and electronic data of the image is obtained, but may be captured by an X-ray film.

  In order to express the present invention, the present invention has been properly and fully described through the embodiments with reference to the drawings. However, those skilled in the art can easily change and / or improve the above-described embodiments. It should be recognized that this is possible. Therefore, unless the modifications or improvements implemented by those skilled in the art are at a level that departs from the scope of the claims recited in the claims, the modifications or improvements are not covered by the claims. To be construed as inclusive.

DG metal lattice SD slit groove 11 first silicon layer 12 lattice 12a second silicon portion 12b metal portion 12c first insulating layer 12d second insulating layer 30 silicon substrate 31 first silicon layer 32 second silicon layer 33 first insulating layer 34 Second insulating layer 100A X-ray Talbot interferometer 100B X-ray Talbot-low interferometer 102, 203 First diffraction grating 103, 202 Second diffraction grating 104 Multi-slit plate 200 X-ray imaging device

Claims (9)

A resist layer forming step of forming a resist layer on a main surface of the second silicon layer in a substrate including a first silicon layer and a second silicon layer attached to the first silicon layer via a first insulating layer; ,
Patterning the resist layer by lithography to remove the resist layer in the patterned portion; and
An etching step of forming a slit groove by etching the second silicon layer corresponding to the portion from which the resist layer has been removed by dry etching until at least the first silicon layer is reached;
An insulating layer forming step of applying a voltage to the second silicon layer by an anodic oxidation method to form a second insulating layer on the surface of the slit groove;
A method for producing a metal grid, comprising: an electroforming step of applying a voltage to the first silicon layer by electroforming to fill the slit groove with metal. The thickness of the second insulating layer is adjusted by a smart cut method so that the sum of the thickness of the first insulating layer and the thickness of the second silicon layer corresponds to the depth of the slit groove. The method for producing a metal grid according to claim 1, further comprising an adjusting step. The method for manufacturing a metal grid according to claim 1, wherein the dry etching method is RIE. The method for manufacturing a metal grid according to claim 1, wherein the dry etching method is a Bosch process. The method for manufacturing a metal lattice according to claim 1, wherein the first silicon layer is n-type silicon. The method for manufacturing a metal lattice according to claim 1, wherein the second silicon layer is p-type silicon.   The manufacturing method of the metal grating of any one of Claim 1 thru | or 6 which manufactures the diffraction grating used for a X-ray Talbot interferometer or a X-ray Talbot low interferometer. A first silicon layer;
A plurality of second silicon portions formed on the first silicon layer and extending linearly in one direction and a lattice in which a plurality of metal portions extending linearly in the one direction are alternately arranged in parallel are provided. ,
A plurality of first insulating layers between each of the first silicon layer and the plurality of second silicon portions;
A metal grid, further comprising a plurality of second insulating layers between each of the plurality of second silicon portions and the plurality of metal portions. An X-ray source emitting X-rays;
A Talbot interferometer or a Talbot-low interferometer irradiated with X-rays emitted from the X-ray source;
An X-ray imaging device that captures an X-ray image by the Talbot interferometer or the Talbot-Lau interferometer,
An X-ray imaging apparatus, wherein the Talbot interferometer or the Talbot-Lau interferometer includes the metal grating according to claim 8.

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