JP7529195B2 - Method for manufacturing X-ray element - Google Patents

Description

Article 30, paragraph 2 of the Patent Act applies [1] Publication name: Abstract of the Graduation Research Presentation, 2019, Tokyo Metropolitan University, Faculty of Science and Technology, Physics Course Publication date: February 6, 2020 <References> Program and Abstract of the Graduation Research Presentation (excerpt) [2] Meeting name: Graduation Research Presentation, 2019, Tokyo Metropolitan University, Faculty of Science and Technology, Physics Course Date held (publication date): February 12, 2020 <References> Presentation slides for the Graduation Research Presentation (excerpt)

The present disclosure relates to a method for manufacturing an X- ray element.

Observing X-rays emitted from celestial bodies is important in the fields of X-ray astronomy and astrophysics, as it deepens our understanding of celestial bodies and phenomena occurring in space. Because X-rays are absorbed by the Earth's atmosphere, devices for observing X-rays are mounted on artificial satellites and transported to altitudes higher than the atmosphere. For this reason, lightweight, high-performance devices are required.

Instruments for observing X-rays are provided with an X-ray element for making X-rays incident on an X-ray detector. X-rays have approximately 1000 times more energy than visible light and have a penetrating power, so even if they are incident on a reflecting surface approximately perpendicularly, they will mostly pass through and the direction of the X-rays cannot be changed. For this reason, oblique incidence optical systems that align the direction of X-rays with the X-ray detector by total reflection at an incidence angle of 1° or less are widely used in devices for observing X-rays. For example, Patent Document 1 discloses an X-ray element for use in an oblique incidence optical system, in which a silicon wafer with multiple curved slits formed by dry etching is bent and deformed at a predetermined radius of curvature.

As described above, a Wolter I type element is known as an X-ray element that can be formed from a substrate such as a silicon wafer, in which multiple membrane-like substrates extending along the center of the X-ray propagation direction are arranged at intervals in the radial direction. However, the manufacture of a Wolter I type element requires multiple steps. A Lobster eye type element, which imitates the eye of a crustacean, has been proposed as an X-ray element that can be manufactured in a single step compared to the Wolter I type. By using a Lobster eye type element, a wide field of view that is symmetrical about the center of the X-ray propagation direction can be obtained.

JP 2010-085304 A

Among the Lobster eye type X-ray elements, those with an Angel configuration have rectangular holes formed when viewed from the direction of travel of the incident ray. Forming rectangular holes in a substrate such as a silicon wafer by dry etching has the advantage that it can be easily achieved using mature technology, but there is a risk that the corners of the hole will be rounded when viewed along the thickness direction. If the corners of the rectangular hole are rounded, there is a problem in that it is difficult to direct the X-rays reflected by the surrounding wall of the hole to the specified position. In other words, there was a demand for an X-ray element that can emit X-rays to a specified position with high precision and can be easily manufactured.

The present invention provides a method for manufacturing an X- ray element that can emit X-rays toward a predetermined position with high precision and can be easily manufactured.

A method for manufacturing an X-ray device according to the present invention includes a first through hole forming step of forming, by dry etching, a first through hole that penetrates a first substrate having a predetermined thickness in a first direction and is longer in a third direction intersecting the first direction and the second direction than in a second direction intersecting the first direction when viewed from the first direction; a second through hole forming step of forming, by dry etching, a second through hole that penetrates a second substrate having a predetermined thickness in the first direction and is longer in the second direction than in the third direction when viewed from the first direction; and a second through hole forming step of forming, by dry etching, a second through hole that penetrates a second substrate having a predetermined thickness in the first direction and is longer in the second direction than in the third direction when viewed from the first direction, such that the first through hole overlaps at least a part of a central portion of the second through hole relative to both ends in the second direction when viewed from the first direction, the second through hole is aligned so as to overlap at least a part of a central portion of the first through hole rather than both ends in the third direction, and the first substrate and the second substrate are overlapped in the first direction , and the first substrate and the second substrate are bent with a predetermined radius of curvature, so that peripheral wall surfaces of the first through hole and the second through hole extend along a fourth direction along a radial direction centered on a predetermined position, both ends of the first substrate in the fourth direction are curved along a fifth direction along a circumferential direction centered on the predetermined position, and both ends of the second substrate in the fourth direction are curved along a sixth direction along the circumferential direction centered on the predetermined position and intersecting the fifth direction.

The manufacturing method of the X-ray element described above may further include a peripheral wall surface processing step of processing the surfaces of the first substrate and the second substrate forming the side walls of the first through hole and the second through hole, respectively, so as to be capable of reflecting X-rays.

In the above-mentioned method for manufacturing an X-ray element, the first substrate and the second substrate are a first semiconductor substrate and a second semiconductor substrate, respectively, and in the peripheral wall surface processing step, a first metal film capable of reflecting X-rays may be formed on the surface of the first semiconductor substrate forming the side wall of the first through hole, and a second metal film capable of reflecting X-rays may be formed on the surface of the second semiconductor substrate forming the side wall of the second through hole.

The present invention provides an X-ray element that can emit X-rays toward a predetermined position with high precision and can be easily manufactured, as well as a method for manufacturing the X-ray element.

1 is a schematic diagram showing how an X-ray detector detects X-rays using an X-ray element according to an embodiment of the present invention; 1 is a front view of an X-ray element according to an embodiment of the present invention, seen from the rear to the front in the direction of X-ray propagation. 3 is a cross-sectional view of the X-ray element shown in FIG. 2 taken along line Z1-Z1. 3 is an enlarged perspective view of a main part of the X-ray element shown in FIG. 2. 1A to 1C are cross-sectional views for explaining a manufacturing method of an X-ray element according to an embodiment of the present invention. 1A to 1C are cross-sectional views for explaining a manufacturing method of an X-ray element according to an embodiment of the present invention. FIG. 7 is an enlarged cross-sectional view of a region M10 shown in FIG. 6. FIG. 7 is another enlarged cross-sectional view of region M10 shown in FIG. 6. FIG. 2 is a perspective view for explaining a manufacturing method of the X-ray element according to the embodiment of the present invention. 1A to 1C are cross-sectional views for explaining a manufacturing method of an X-ray element according to an embodiment of the present invention. 11 is an enlarged cross-sectional view of a region M11 shown in FIG. 10. FIG. 13 is an enlarged perspective view of a main part of a conventional X-ray element. FIG. 2 is a plan view of a photomask used in the examples. 14 is an enlarged view of a unit pattern (region M1) of the photomask shown in FIG. 13. FIG. 14 is an enlarged view of a region M2 of the photomask shown in FIG. 13. FIG. 14 is an enlarged view of a region M3 of the photomask shown in FIG. 13. 14 is an optical microscope photograph of a Si substrate viewed from the front side when a plurality of first through holes are formed in the Si substrate using the photomask shown in FIG. 13. 14 is an optical microscope photograph of a Si substrate viewed from the back side when a plurality of first through holes are formed in the Si substrate using the photomask shown in FIG. 13. 1 is an optical microscope photograph of a Si substrate in an example in which a plurality of rectangular through holes are formed in the Si substrate, as viewed from the front side. 1 is an optical microscope photograph of a Si substrate in an embodiment in which a plurality of rectangular through holes are formed, as viewed from the back side of the Si substrate. 11 is a graph showing the results of measuring the roughness of the peripheral wall surface of a first through hole in a first pattern in an example. 13 is a graph showing the results of measuring the roughness of the peripheral wall surface of a first through hole of a second pattern in an example. FIG. 2 is a plan view of a first Si substrate in the embodiment. FIG. 4 is a plan view of a second Si substrate in the embodiment. FIG. 2 is a plan view of a first Si substrate and a second Si substrate combined together in an embodiment.

As shown in FIG. 1, an X-ray element 10 according to an embodiment of the present invention collects X-rays 100 from a celestial body (not shown) on an X-ray detector 200, making them detectable by the X-ray detector 200.

The X-ray element 10 includes a first layer 21 and a second layer 22, and has a laminated structure of the first layer 21 and the second layer 22. As shown in FIG. 2, the first layer 21 includes a semiconductor substrate (first semiconductor substrate) 25 and a metal film (first metal film) 61. The second layer 22 includes a semiconductor substrate (second semiconductor substrate) 26 and a metal film (second metal film) 62. The semiconductor substrates 25 and 26 are formed of a semiconductor that can be processed and bent by photolithography and etching techniques, for example, silicon (Si). As shown in FIGS. 1 to 3, in the X-ray element 10, a first direction (fourth direction) R1 represents a radial direction centered on a predetermined position 50 where the X-rays 100 are concentrated in the X-ray detector 200. The diameter of the semiconductor substrates 25, 26 before bending as viewed from the first direction R1 is, for example, about 3 inches to 12 inches (i.e., 76.2 mm to 304.8 mm), but is set appropriately taking into consideration the conditions required for the X-ray element 10, etc.

As shown in FIG. 1 to FIG. 3, the second direction (sixth direction) S2 is included in the curved surface intersecting with the first direction R1, and is one of the circumferential directions centered on the position 50. The third direction (fifth direction) S3 is a direction along the circumferential direction centered on the position 50 and intersecting with the second direction S2, and is one of the circumferential directions centered on the position 50. The first layer 21 has a predetermined thickness T21 in the first direction R1, is formed in a circular shape when viewed from the first direction R1, is along the curved surface centered on the predetermined position 50, and has a predetermined size. The second layer 22 has a predetermined thickness T22 in the first direction R1, is formed in a circular shape when viewed from the first direction R1, is along the curved surface centered on the predetermined position 50, and has a predetermined size. Each of the thicknesses T21 and T22 is, for example, about 100 μm to 1000 μm, but is appropriately set in consideration of the conditions required for the X-ray element 10. The second layer 22 is disposed forward of the first layer 21 in the direction of travel of the X-rays 100, i.e., between the first layer 21 and the X-ray detector 200 in the first direction R1, and is adjacent to the first layer 21 in the first direction R1.

The semiconductor substrate 25 is formed with a plurality of first through holes 31 penetrating in the first direction R1. The plurality of first through holes 31 are formed at intervals from one another in the second direction S2 along the circumferential direction centered on the position 50. When viewed from the first direction R1, the size L33 of each of the first through holes 31 in the third direction S3 is larger than the size L32 of the same first through hole 31 in the second direction S2. FIG. 2 illustrates the sizes L32, L33 of one first through hole 31-1 among the plurality of first through holes 31. The sizes L32 of the plurality of first through holes 31 are substantially the same. On the other hand, the sizes L33 of the first through holes 31 adjacent to each other in the second direction S2 among the plurality of first through holes 31 are different from one another.

A plurality of second through holes 32 penetrating in the first direction R1 are formed in the semiconductor substrate 26. The plurality of second through holes 32 are formed at intervals from each other in the third direction S3. When viewed from the first direction R1, the size L35 of each second through hole 32 in the second direction S2 is larger than the size L36 of the same second through hole 32 in the third direction S3. FIG. 2 illustrates the sizes L35 and L36 of one second through hole 32-1 among the plurality of second through holes 32. The sizes L36 of the plurality of second through holes 32 are approximately the same. On the other hand, the sizes L35 of the second through holes 32 adjacent to each other in the third direction S3 among the plurality of second through holes 32 are different from each other. In FIG. 1, the thickness of the first layer 21 between the first through holes 31 adjacent to each other in the second direction S2 and the thickness of the second layer 22 between the second through holes 32 adjacent to each other in the third direction S3 are substantially omitted.

As an example, FIG. 4 is an enlarged view of the first through hole 31-1 and the first layer 21 constituting the peripheral wall thereof, and the second through hole 32-1 and the second layer 22 constituting the peripheral wall thereof. As shown in FIG. 2 and FIG. 4, when viewed from the first direction R1, the first through hole 31-1 overlaps with a part of the central portion 43 of the second through hole 32-1, which is closer to the center than the ends 41 and 42 in the second direction S2. The end 41 of the second through hole 32-1 (i.e., the end on the left side of the paper in FIG. 2) represents the region in the second direction S2 from one end of the second through hole 32-1 in the second direction S2 (i.e., the end on the left side of the paper in FIG. 2) to a position moved a predetermined dimension toward the other end. The predetermined dimension is approximately the same as the radius of curvature of the roundness generated at the corner when a rectangular through hole is formed in the semiconductor substrate 25 by etching technology, and is, for example, about 5 μm or about 1 μm. The end 42 of the second through hole 32-1 (i.e., the end on the right side of the paper in FIG. 2) refers to the region in the second direction S2 from the other end of the second through hole 32-1 in the second direction S2 (i.e., the end on the right side of the paper in FIG. 2) toward one end by the above-mentioned specified dimension.

When viewed from the first direction R1, the second through hole 32-1 overlaps with a part of the central portion 47 of the first through hole 31-1, which is closer to the center than the ends 45 and 46 in the third direction S3. The end 45 of the first through hole 31-1 (i.e., the end on the upper side of the paper in FIG. 2) represents the area in the third direction S3 from one end of the first through hole 31-1 in the third direction S3 (i.e., the end on the upper side of the paper in FIG. 2) to the other end by the above-mentioned predetermined dimension. The end 46 of the first through hole 31-1 (i.e., the end on the lower side of the paper in FIG. 2) represents the area in the third direction S3 from the other end of the first through hole 31-1 in the third direction S3 (i.e., the end on the lower side of the paper in FIG. 2) to the position moved by the above-mentioned predetermined dimension toward one end.

As shown in FIG. 4, when viewed from the first direction R1, the peripheral wall surface 71 of each first through hole 31 is configured to be able to reflect X-rays. Similarly, when viewed from the first direction R1, the peripheral wall surface 72 of each second through hole 32 is configured to be able to reflect X-rays. The roughness of each of the peripheral wall surfaces 71, 72 is at least 10 nm or less, preferably 5 nm or less, and more preferably 1 nm or less. The roughness of each of the peripheral wall surfaces 71, 72 means, for example, the root mean square (RMS) roughness. The above-mentioned roughness is a value that can be measured by an appropriate measurement method, for example, obtained by observation using an atomic force microscope.

Specifically, a metal film 61 is provided on the side surfaces (surfaces) 25a, 25b of the semiconductor substrate 25 that form the peripheral walls of the first through hole 31. A surface 61a of the metal film 61 is exposed to the first through hole 31. A metal film 62 is provided on the side surfaces 26a, 26b of the semiconductor substrate 26 that form the peripheral walls of the second through hole 32. A surface 62a of the metal film 62 is exposed to the first through hole 31. The roughness of each of the surface 61a of the metal film 61 and the surface 62a of the metal film 62 is at least 10 nm or less, preferably 5 nm or less, and more preferably 1 nm or less. The metal films 61, 62 are formed of a metal capable of reflecting X-rays, and preferably contain a heavy metal. Examples of oxides of heavy metals forming the metal films 61 and 62 include hafnium oxide ( _HfO2 ), iridium oxide ( _IrO2 ), tantalum oxide ( _TaO2 , _Ta2O5 ), titanium oxide ( _TiO2 ), _lanthanum oxide ( _La2O3 ), _and zinc oxide (ZnO). Examples of nitrides include titanium nitride (TiN), tantalum _nitride ( _Ta3N5 ), and hafnium nitride (HfZn). Examples of metals forming the metal films 61 and 62 include rubidium (Rb), copper (Cu), tungsten (W), molybdenum (M), platinum (Pt), nickel (Ni), and cobalt (Co).

The X-ray element 10 having the above-mentioned configuration has a lattice-shaped through hole 80 formed when viewed from the first direction R1. The depth of the through hole 80 in the first direction R1 corresponds to the sum of the thickness T21 and the thickness T22. The range of the through hole 80 corresponding to the thickness T21 on the rear side of the traveling direction of the X-ray 100 is the center part 47 of the first through hole 31, and the range of the through hole 80 corresponding to the thickness T22 on the front side of the traveling direction of the X-ray 100 from the first through hole 31 is the center part 43 of the second through hole 32. In FIG. 3, the metal films 61 and 62 are omitted. As shown in FIG. 1 and FIG. 3, the first layer 21 and the second layer 22 are curved with a predetermined radius of curvature centered on the position 50 where the X-rays 100 gather, so that the incident X-rays 100 are incident on the surface 61a of the metal film 61 at an incident angle of about 1° and are totally reflected, and are incident on the surface 62a of the metal film 62 at an incident angle of about 1° and are totally reflected. The specified radius of curvature is, for example, about 10 cm to 10 m, and is set appropriately to accommodate the behavior of X-rays as described above.

As shown in FIG. 4, for example, X-rays 100 that enter through-hole 80 at an angle of several degrees with respect to first direction R1 are first totally reflected by metal film 61 along third direction S3, pass through first through-hole 31, are then totally reflected by metal film 62 along second direction S2, pass through second through-hole 32, are emitted from through-hole 80, and travel toward X-ray detector 200. That is, X-rays 100 travel toward position 50 by being reflected twice by through-hole 80.

Next, a method for manufacturing an X-ray element according to one embodiment of the present invention will be described. The method for manufacturing an X-ray element according to this embodiment is a method for manufacturing the above-mentioned X-ray element 10, and includes a first through-hole forming process, a second through-hole forming process, a positioning process, a curvature imparting process, and a peripheral wall surface processing process.

In the first through hole forming process, a plurality of first through holes 31 are formed in a semiconductor substrate (first substrate) 25 such as a Si substrate. To explain in detail, as shown in FIG. 5, for example, an aluminum (AL) film 110 is evaporated on a surface 25c of a semiconductor substrate 25 having a predetermined thickness T1 in a first direction D1, and a resist protective film 112 is formed on the AL film 110. A photomask 120 is placed on the resist protective film 112. A pattern is formed on the photomask 120 in accordance with the plurality of first through holes 31. In the example shown in FIG. 5, the portion where the first through holes 31 are formed is made of quartz or the like that transmits ultraviolet (UV), and the pattern 122 is drawn on the portion where the first through holes 31 are not formed with a non-transparent material that does not transmit UV such as chromium (Cr). That is, the portion of the quartz where the non-transparent member is not drawn is formed longer in a third direction D3 that is approximately perpendicular (intersecting) to the first direction D1 and the second direction D3 than in a second direction D2 that is approximately perpendicular (intersecting) to the first direction D1 when viewed from the first direction D1. As shown in FIG. 6, UV is irradiated from above the photomask 120, and the pattern 122 of the photomask 120 is transferred to the resist protective film 112 and the AL film by photolithography.

Next, as shown in Figures 7 and 8, the semiconductor substrate 25 is etched by dry etching at a portion where the AL film 110 is not provided and the surface 25c is exposed when viewed from the first direction D1, to form a plurality of first through holes 31 penetrating the semiconductor substrate 25 in the first direction D1. If the semiconductor substrate 25 is a silicon substrate, it can be etched using, for example, sulfur hexafluoride (SF ₆ ) gas as shown in Figure 7. As shown in Figure 8, a protective film 128 is formed on a wall surface (surface) 25w forming a sidewall of the first through hole 31 penetrating in the first direction D1. Note that n in Figure 8 represents any natural number equal to or greater than 2.

Next, in the above-mentioned first through hole forming step, the semiconductor substrate 25 is replaced with a semiconductor substrate (second substrate) 26, and the second through hole forming step is performed in the same manner as the procedure described with reference to FIG. 5 to FIG. 8. However, in the second through hole forming step, the quartz portion where the non-transparent member of the photomask pattern is not drawn is formed longer in the second direction D2 than in the third direction D3 when viewed from the first direction D1. In the second through hole forming step, a plurality of second through holes 32 are formed in the semiconductor substrate 26. Various conditions, such as the flow rate of SF 6 gas or other gases used in etching, are adjusted so that the roughness of each of the wall surface 25w of the semiconductor substrate 25 and the wall surface (surface) 26w forming the side wall of the second through hole ₃₂ in the semiconductor substrate 26 is at least 10 nm or less, preferably 5 nm or less, and more preferably 1 nm or less. After the etching is completed, the resist protective film 112 and the protective film 128 are removed by ashing at an appropriate time.

In order to overlap the semiconductor substrates 25, 26 in the first direction D1 in the alignment process described below, it is preferable that the pattern of the photomask 120 used in each of the first through hole forming process and the second through hole forming process has alignment marks or patterns (hereinafter simply referred to as alignment patterns) formed in positions different from the positions where the multiple first through holes 31 and the multiple second through holes 32 are formed. This allows the alignment pattern to be formed in the area on the surface 25c of the semiconductor substrate 25 where the multiple first through holes 31 are not formed, as shown in FIG. 9. Also, the alignment pattern can be formed in the area on the surface of the semiconductor substrate 26 where the multiple second through holes 32 are not formed.

Next, in the alignment process, the alignment pattern 151 of the semiconductor substrate 25 is aligned with the alignment pattern 152 formed on the semiconductor substrate 26 so that the first through hole 31 overlaps at least a part of the center of the second through hole 32 more than both ends in the second direction D2 when viewed from the first direction D1, and the second through hole 32 overlaps at least a part of the center of the first through hole 31 more than both ends in the third direction D3. The semiconductor substrates 25 and 26 are overlapped in the first direction D1 while being aligned with each other. Note that both ends of the first through hole 31 represent the region in the third direction S3 from both ends of the first through hole 31 in the third direction D3 toward the center by the above-mentioned predetermined dimension. Both ends of the second through hole 32 represent the region in the second direction S2 from both ends of the second through hole 32 in the second direction D2 toward the center by the above-mentioned predetermined dimension.

As described above, by aligning the alignment patterns 151, 152 to form a predetermined shape or by matching them with each other, the first through hole 31 can be overlapped with at least a portion of the center of the second through hole 32 in the second direction D2 when viewed from the first direction D1, and the second through hole 32 can be overlapped with at least a portion of the center of the first through hole 31 in the third direction D3.

Next, in the curvature imparting process, the stacked semiconductor substrates 25, 26 are bent with a predetermined radius of curvature as shown in FIG. 10. Note that each of the semiconductor substrates 25, 26 after the peripheral wall surface processing process may be individually bent with a predetermined radius of curvature, and the semiconductor substrates 25, 26 may be stacked in the first direction R1 (i.e., the first direction D1 before bending) taking into account the degree of overlap of the alignment patterns 151, 152.

Next, in the peripheral wall processing step, as shown in FIG. 11, the wall surface 25w of the semiconductor substrate 25 forming the peripheral wall surface of the first through hole 31 and the wall surface 26w of the semiconductor substrate 26 forming the peripheral wall surface of the second through hole 32 are processed to be able to reflect X-rays. To explain in detail, a metal film 61 is formed on the wall surface 25w of the semiconductor substrate 25 by, for example, atomic layer deposition. Similarly, a metal film 62 is formed on the wall surface 26w of the semiconductor substrate 26 by atomic layer deposition. The settings and conditions for forming the metal film are adjusted so that the roughness of each of the surface 61a of the metal film 61 and the surface 62a of the metal film 62 is at least 10 nm or less, preferably 5 nm or less, and more preferably 1 nm or less.

By carrying out each of the above steps, the X-ray element 10 can be manufactured.

The X-ray element 10 of the present embodiment described above includes a first layer 21 and a second layer 22. The first layer 21 has a thickness T21 in a first direction R1 along the radial direction of the position 50. The second layer 22 has a thickness T22 in the first direction R1 and is adjacent to the first layer in the first direction. The first layer 21 has a plurality of first through holes 31 penetrating in the first direction R1. When viewed from the first direction R1, the size of the first through hole 31 in the third direction S3 is larger than the size of the first through hole 31 in the second direction S2. The second layer 22 has a plurality of second through holes 32 penetrating in the first direction R1. When viewed from the first direction R1, the size of the second through hole 32 in the second direction S2 is larger than the size of the second through hole 32 in the third direction S3. When viewed from the first direction R1, the first through hole 31 overlaps with the center of the second through hole in the second direction S2. The second through hole 32 overlaps with the center of the first through hole in the third direction S3. In the first through hole 31 of the first layer 21, the peripheral wall surface 71 in the first direction R1 is configured to be able to totally reflect the X-rays 100. In addition, in the second through hole 32 of the second layer 22, the peripheral wall surface 72 in the first direction R1 is configured to be able to totally reflect the X-rays 100. The roughness of each of the peripheral wall surfaces 71, 72 is 10 nm or less.

In the X-ray element 10 of this embodiment, the first through hole 31 of the first layer 21 does not overlap with the ends 41, 42 of the second through hole 32 in the first direction R1, but overlaps with the center 43. In addition, the second through hole 32 of the second layer 22 does not overlap with the ends 45, 46 of the first through hole 31 in the first direction R1, but overlaps with the center 47. When a rectangular through hole 231 is formed in the single layer 221 by dry etching as in the conventional X-ray element 250 called the Angel arrangement illustrated in FIG. 12, as viewed from the first direction R1, the corners of the through hole 231 are rounded. In the X-ray element 10 of this embodiment, when viewed from the first direction R1, the semiconductor substrate 25 at the ends 45, 46 of the first through hole 31 and the semiconductor substrate 26 at the ends 41, 42 of the second through hole 32 shown in FIG. 2, etc. are rounded. On the other hand, the semiconductor substrate 25 at the center 47 of the first through hole 31 and the semiconductor substrate 26 at the center 43 of the second through hole 32 extend linearly along the third direction S3 and the second direction S2, and are not rounded at all. Therefore, as shown in FIG. 4, according to the X-ray element 10 of this embodiment, a lattice-shaped plurality of through holes 80 with no rounded corners can be formed when viewed from the first direction S1. The X-ray 100 that enters the plurality of through holes 80 and is totally reflected twice is precisely focused at the position 50. In addition, regardless of the rounding of the semiconductor substrate 25 at the ends 45, 46 of the first through hole 31 and the semiconductor substrate 26 at the ends 41, 42 of the second through hole 32, the stacked structure of the first layer 21 and the second layer 22 realizes the through hole 80 with no rounded corners, and the X-ray element 10 can be easily manufactured.

In the X-ray element 10 of this embodiment, the roughness of each of the peripheral wall surfaces 71, 72 is 10 nm or less, so that diffuse reflection of the X-rays 100 during total reflection is suppressed, and the X-rays 100 can be emitted satisfactorily toward the position 50. As a result, the X-ray element 10 of this embodiment can emit the X-rays 100 toward the position 50 with high precision and can be easily manufactured.

In the X-ray element 10 of this embodiment, the first layer 21 includes a semiconductor substrate 25 and a metal film 61 capable of reflecting X-rays 100. The second layer 22 includes a semiconductor substrate 26 and a metal film 62 capable of reflecting X-rays 100. The first through-hole 31 is formed in the semiconductor substrate 25, and the second through-hole 32 is formed in the semiconductor substrate 26. The metal film 61 is provided on the side surfaces 25a and 25b of the semiconductor substrate 25 that form the side walls of the first through-hole 31. The metal film 62 is provided on the side surfaces 26a and 26b of the semiconductor substrate 26 that form the side walls of the second through-hole 32.

According to the X-ray element 10 of this embodiment, by providing a semiconductor substrate 25 as the base material of the first layer 21, the first through hole 31 and the second through hole 32 are formed with good shape accuracy and easy manufacturing using lithography technology and dry etching technology. In addition, the peripheral wall surface 71 of the first through hole 31 is formed as a surface 61a having a roughness of 10 nm or less in the metal film 61. The peripheral wall surface 72 of the second through hole 32 is formed as a surface 62a having a roughness of 10 nm or less in the metal film 62. Therefore, according to the X-ray element 10 of this embodiment, the X-ray 100 can be emitted toward the position 50 with high accuracy and can be easily manufactured.

The manufacturing method of the X-ray element of this embodiment includes the first through hole forming process, the second through hole forming process, the alignment process, the curvature imparting process, and the peripheral wall surface processing process described above. In the first through hole forming process, a plurality of first through holes 31 are formed in a first substrate (e.g., semiconductor substrate 25). In the second through hole forming process, a plurality of second through holes 32 are formed in a second substrate (e.g., semiconductor substrate 26). The surface roughness of the peripheral wall surface of at least the first through hole 31 and the second through hole 32 in the semiconductor substrates 25 and 26 is at least 10 nm or less, preferably 5 nm or less, and more preferably 1 nm or less. In the positioning step, the first through hole 31 is aligned so that it overlaps at least a part of the center of the second through hole 32 in the second direction D2 when viewed from the first direction D1, and the second through hole 32 is aligned so that it overlaps at least a part of the center of the first through hole 31 in the third direction D3, and the semiconductor substrates 25 and 26 are overlapped in the first direction D1. In the curvature imparting step, the semiconductor substrates 25 and 26 are bent with a predetermined radius of curvature to impart a curvature to each of the semiconductor substrates 25 and 26. In the peripheral wall surface processing step, the surfaces of the semiconductor substrates 25 and 26 that form the peripheral wall surfaces of each of the first through hole 31 and the second through hole 32 are processed so as to be able to reflect X-rays. In the peripheral wall surface processing step, the roughness of each peripheral wall surface is set to at least 10 nm or less, preferably 5 nm or less, and more preferably 1 nm or less. It is acceptable for the overall roughness of the semiconductor substrates 25 and 26 to be 10 nm or less.

According to the manufacturing method of the X-ray element of this embodiment, even if the semiconductor substrate 25 at the ends 45, 46 of the first through hole 31 and the semiconductor substrate 26 at the ends 41, 42 of the second through hole 32 are rounded, the central portion 47 of the first through hole 31 in the third direction D3 and the central portion 43 of the second through hole 32 in the second direction D2 can be overlapped when viewed from the first direction D1. Therefore, the laminated structure of the first layer 21 and the second layer 22 realizes a lattice-shaped through hole 80 with no rounded corners, and the X-ray element 10 can be easily manufactured. In addition, in the X-ray element 10 of this embodiment, the roughness of each of the peripheral wall surfaces 71, 72 is set to 10 nm or less, so that the diffuse reflection of the X-ray 100 when totally reflected by each of the peripheral wall surfaces 71, 72 is suppressed, and the X-ray 100 can be emitted favorably toward the position 50. As a result, according to the manufacturing method of the X-ray element of this embodiment, the X-ray element 10 capable of emitting the X-ray 100 toward the position 50 with high accuracy can be easily manufactured.

In the manufacturing method of the X-ray element of this embodiment, the first substrate is a semiconductor substrate 25, and the second substrate is a semiconductor substrate 26. In the peripheral wall surface processing step, a metal film 61 capable of reflecting X-rays is formed on the side surfaces 25a and 25b of the semiconductor substrate 25 that form the side walls of the first through hole 31. In the same step, a metal film 62 capable of reflecting X-rays is formed on the surface of the semiconductor substrate 26 that forms the side walls of the second through hole 32. The roughness of the surface 61a of the metal film 61 is at least 10 nm or less, preferably 5 nm or less, and more preferably 1 nm or less. According to the manufacturing method of the X-ray element of this embodiment, the first through hole 31 and the second through hole 32 can be easily formed with good shape accuracy using lithography technology and dry etching technology. In addition, a surface 61a having a roughness of 10 nm or less is formed in the metal film 61 as the peripheral wall surface 71 of the first through hole 31. A surface 62a having a roughness of 10 nm or less is formed in the metal film 62 as the peripheral wall surface 72 of the second through hole 32. Therefore, according to the manufacturing method of the X-ray element of this embodiment, it is possible to easily manufacture the X-ray element 10 that emits X-rays 100 toward the position 50 with high precision.

The above describes in detail preferred embodiments of the present invention. The present invention is not limited to the above-described embodiments. The present invention can be modified within the scope of the gist of the present invention described in the claims.

For example, when the first layer 21 and the second layer 22 are formed of a substrate capable of reflecting X-rays, such as the aforementioned heavy metal or a substrate containing a metal, and lithography and dry etching techniques can be applied to them, it is not necessary to provide metal films 61, 62 on the wall surfaces forming the side walls of the first through hole 31 and the second through hole 32, and it is sufficient to process the wall surfaces forming the side walls of the first through hole 31 and the second through hole 32 so that the roughness of the wall surfaces is 10 nm or less.

For example, the above-mentioned X-ray element 10 has a plurality of first through holes 31 and a plurality of second through holes 32 formed therein, but the number of each of the first through holes 31 and the second through holes 32 is not particularly limited. Furthermore, as long as the first through hole 31 overlaps at least a portion of the center of the second through hole 32 in the second direction D2 when viewed from the first direction D1, and the second through hole 32 overlaps at least a portion of the center of the first through hole 31 in the third direction D3, the sizes L32, L33 of the plurality of first through holes 31 and the sizes L35, L36 of the plurality of second through holes 32 can be changed as appropriate.

For example, in the above-mentioned manufacturing method of the X-ray element 10, an example has been described in which the peripheral wall surface processing step is performed after the curvature imparting step, but if the metal films 61, 62 have a predetermined shape after the curvature is imparted to the semiconductor substrates 25, 26 in the curvature imparting step, the peripheral wall surface processing step may be performed after the alignment step and before the curvature imparting step, or may be performed before the alignment step.

In addition, in the manufacturing method of the X-ray element according to the present invention, the first and second substrates are not limited to the semiconductor substrates 25 and 26, so long as they are substrates to which lithography and dry etching techniques can be applied. If the first and second substrates are base materials to which lithography and dry etching techniques can be applied and which can reflect X-rays, the peripheral wall surface processing step does not need to be performed, and the X-ray element can be manufactured, for example, by performing each step up to the curvature imparting step in the manufacturing method of the X-ray element described above.

Next, examples of the present invention will be described. Note that the present invention is not limited to the following examples.

In this embodiment, the precursors of the first layer 21 and the second layer of the X-ray element 10, i.e., the first layer and the second layer before bending with a predetermined radius of curvature, were formed according to the manufacturing method of the X-ray element described above. A photomask with a radius of 5 cm and two Si substrates were prepared. As shown in FIG. 13, the surface of the photomask is partitioned at 90° intervals in the circumferential direction from the center. In the partitions facing each other from the center, patterns are drawn point-symmetrically with respect to the center. That is, two types of patterns are formed on the photomask used. The unit pattern common to the two types of patterns includes multiple slits, as shown in FIG. 14. The vertical size of the slit is 1980 μm, and the horizontal size of the slit is 16 μm. The horizontal interval between the slits is 24 μm.

As shown in FIG. 15, the first pattern has a plurality of unit patterns arranged at intervals of 300 μm in both the vertical and horizontal directions. As shown in FIG. 16, the second pattern has a plurality of unit patterns arranged at intervals of 300 μm in both the vertical and horizontal directions. Using this photomask, two types of patterns of the photomask were transferred to two Si substrates by lithography and dry etching techniques, forming first and second through holes having the same shape as the multiple slits.

17 and 18 are optical microscope photographs of the lateral end of the first through-hole of the first pattern taken from the front and back sides of the Si substrate. As shown in FIG. 17 and FIG. 18, it can be seen that the corners of the end of the first through-hole are rounded. It can also be seen that the radius of curvature of the roundness is larger on the back side of the Si substrate than on the front side. As a reference example, FIG. 19 and FIG. 20 show optical microscope photographs taken from the front and back sides of the Si substrate when through-holes are formed in a rectangular pattern of X-ray elements called Angel arrangement. As shown in FIG. 19 and FIG. 20, it can be seen that even rectangular through-holes have rounded corners, making it difficult to secure a center that is not rounded. In the reference example, the radius of curvature of the roundness is larger on the back side of the Si substrate than on the front side.

The roughness of the Si substrate on the sidewalls of the first and second through-holes was measured using a stylus-type roughness tester (Dektak 6M; manufactured by BRUKER) and the results are shown in Figures 21 and 22. As shown in Figures 21 and 22, the surface roughness of the metal film was 10 nm or less, and it can be seen that it was smooth. Next, a metal film made of Pt was formed on the sidewalls of the first through-holes in the Si substrate.

As shown in FIG. 23, a first Si substrate having a plurality of first through holes formed therein and as shown in FIG. 24, a second Si substrate having a plurality of second through holes formed therein are overlapped when rotated 90° from each other's center. As shown in FIG. 25, a lattice-shaped through hole can be formed by matching the alignment patterns of the first Si substrate and the second Si substrate and overlapping the first Si substrate on the second Si substrate.

From the results obtained in the examples described above, it was confirmed that the manufacturing method of the X-ray element described in the above embodiment can provide an X-ray element that can emit X-rays toward a predetermined position with high precision and can be easily manufactured.

10...X-ray element, 21...first layer, 22...second layer, 25...semiconductor substrate (first semiconductor substrate), 26...semiconductor substrate (second semiconductor substrate), 31...first through hole, 32...second through hole, 61...metal film (first metal film), 62...metal film (second metal film)

Claims (3)

a first through hole forming step of forming, by dry etching, a first through hole which penetrates a first substrate having a predetermined thickness in a first direction and is longer in a third direction intersecting the first direction and the second direction than in a second direction intersecting the first direction when viewed from the first direction;
a second through hole forming step of forming, by dry etching, a second substrate having a predetermined thickness in a first direction, a second through hole penetrating the second substrate in the first direction and being longer in the second direction than in the third direction when viewed from the first direction;
an alignment process of overlapping the first substrate and the second substrate in the first direction such that, when viewed from the first direction, the first through hole overlaps with at least a part of a central portion of the second through hole relative to both ends in the second direction and the second through hole overlaps with at least a part of a central portion of the first through hole relative to both ends in the third direction;
a curvature imparting step of bending the first substrate and the second substrate with a predetermined radius of curvature, extending peripheral wall surfaces of each of the first through hole and the second through hole along a fourth direction along a radial direction centered on a predetermined position, curving both ends of the first substrate in the fourth direction along a fifth direction along a circumferential direction centered on the predetermined position, and curving both ends of the second substrate in the fourth direction along a sixth direction that is circumferential about the predetermined position and intersects with the fifth direction;
Equipped with
the surface roughness of the side wall of the first through hole and the surface roughness of the side wall of the second through hole are each set to 10 nm or less;
A method for manufacturing an X-ray element. a peripheral wall surface processing step of processing surfaces of the first substrate and the second substrate forming side walls of the first through hole and the second through hole so as to be capable of reflecting X-rays,
The method for manufacturing the X-ray device according to claim 1 . the first substrate and the second substrate are a first semiconductor substrate and a second semiconductor substrate, respectively;
In the peripheral wall surface processing step,
forming a first metal film capable of reflecting X-rays on a surface of the first semiconductor substrate that forms a side wall of the first through hole;
forming a second metal film capable of reflecting X-rays on a surface of the second semiconductor substrate that forms a side wall of the second through hole;
The method for manufacturing an X-ray device according to claim 2 .

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