Imaging apparatus and image generation method

Abstract

To provide an imaging apparatus and an image generation method, capable of acquiring a reconstructed image with high accuracy, while simplifying the manufacture of the apparatus.SOLUTION: The imaging apparatus includes an image detector 14 and a control analysis part 31. The image detector 14 includes a first pixel layer 140 in which a linear pixel 141 extending in a first direction is arranged, a second pixel layer 150 in which a linear pixel 151 extending in a second direction is arranged, and a third pixel layer 160 in which a plurality of linear pixels 161 extending in a third direction are arranged. The control analysis part 31 creates a set of deformation parts by extracting a first deformation part from a first detection strength profile output from the linear pixel 141, a second deformation part from a second detection strength profile output from the linear pixel 151, and a third deformation part from a third detection strength profile output from the linear pixels 161 respectively. A small area image is reconstructed and then superimposed on the basis of the set of deformation parts, to generate an image of a subject.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present embodiment relates to an imaging device and an image generating method. [Background technology]

[0002] A transmission X-ray microscope is known as a device for observing the structure of a specimen with high resolution and in a non-destructive manner. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6478433 [Patent Document 2] Patent No. 7062547 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present embodiment is to provide an imaging device and an image generating method that can acquire a highly accurate reconstructed image while simplifying the manufacturing of the device. [Means for solving the problem]

[0005] The imaging device of this embodiment includes a stage for holding a subject, a detector formed by stacking a first pixel layer, a second pixel layer, and a third pixel layer in that order with an insulating film interposed therebetween, an imaging optical element for focusing imaging light transmitted through the subject on a detector element of the detector, and an image processing unit for reconstructing an image of the subject from a detection intensity, which is the intensity of the imaging light detected by the detector.

[0006] The first pixel layer includes a plurality of first linear pixels having linear light receiving surfaces extending in a first direction, the plurality of first linear pixels being arranged at equal intervals in a plane parallel to the first pixel layer, and the second pixel layer includes a plurality of second linear pixels having linear light receiving surfaces extending in a second direction, the plurality of second linear pixels being arranged at equal intervals in a plane parallel to the second pixel layer.

[0007] The third pixel layer includes a plurality of third linear pixels having linear light receiving surfaces extending in a third direction, and the third linear pixels are arranged at equal intervals in a plane parallel to the third pixel layer. Furthermore, the first direction, the second direction, and the third direction are different from each other.

[0008] The detector outputs a first detection intensity profile, which is the detection intensity detected in the first pixel layer, a second detection intensity profile, which is the detection intensity detected in the second pixel layer, and a third detection intensity profile, which is the detection intensity detected in the third pixel layer.

[0009] The image processing unit extracts one or more first deformation units from the first detection intensity profile, one or more second deformation units from the second detection intensity profile, and one or more third deformation units from the third detection intensity profile. The image processing unit also creates one or more deformation unit sets each consisting of one of the first deformation units, one of the second deformation units, and one of the third deformation units. The image processing unit then reconstructs a small region image for each of the deformation unit sets based on the first to third deformation units included in the deformation unit set, and generates an image of the subject by overlaying all of the reconstructed small region images. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of the configuration of an imaging apparatus according to a first embodiment. [Figure 2] FIG. 1 is a schematic diagram illustrating an example of a subject. [Figure 3] FIG. 2 is a plan view illustrating an example of a memory cell array formed in a memory chip corresponding region. [Figure 4] FIG. 2 is a plan view illustrating an example of a detailed structure of a memory cell array. [Figure 5] FIG. 2 is a view for explaining an example of a cross section of an image detector in the first embodiment. [Figure 6A] FIG. 2 is a plan view of the first pixel layer as viewed from above in the Z direction. [Figure 6B] FIG. 10 is a plan view of the second pixel layer as viewed from above in the Z direction. [Figure 6C] FIG. 10 is a plan view of the third pixel layer viewed from above in the Z direction. [Figure 6D] FIG. 10 is a plan view of the fourth pixel layer as viewed from above in the Z direction. [Figure 7] The diagram shows the basic circuit configuration of an image detector. [Figure 8] A diagram explaining the principle of X-ray photon detection in a superconducting strip. [Figure 9] 4 is a flowchart illustrating an example of an image generating method according to the first embodiment. [Figure 10A] FIG. 3 is a diagram illustrating an example of an image formed on a detection object. [Figure 10B] 10B is a diagram illustrating an example of first and second detection intensity profiles of the image shown in FIG. 10A. FIG. [Figure 10C] 10B is a diagram illustrating an example of third and fourth detection intensity profiles of the image shown in FIG. 10A. [Figure 11A] FIG. 3 is a diagram illustrating the positional relationship between first line-shaped pixels and second line-shaped pixels. [Figure 11B] 5A and 5B are diagrams illustrating examples of first and second detection intensity profiles. [Figure 12A] FIG. 10 is a diagram illustrating another example of an image formed on a detection object. [Figure 12B] 12B is a diagram illustrating an example of first and second detection intensity profiles of the image shown in FIG. 12A. FIG. [Figure 12C] 12B is a diagram illustrating an example of third and fourth detection intensity profiles of the image shown in FIG. 12A. [Figure 13A] FIG. 10 is a diagram illustrating another example of an image formed on a detection object. [Figure 13B] 13B is a diagram illustrating an example of first and second detection intensity profiles of the image shown in FIG. 13A. FIG. [Figure 13C] 13B is a diagram illustrating an example of third and fourth detection intensity profiles of the image shown in FIG. 13A. [Figure 14A] FIG. 10 is a diagram illustrating an example of a reconstructed small-region image. [Figure 14B] FIG. 10 is a diagram illustrating an example of a reconstructed small-region image. [Figure 14C] FIG. 10 is a diagram illustrating an example of a reconstructed image. [Figure 15A] FIG. 10 is a diagram illustrating another example of an image formed on a detection object. [Figure 15B] 15B is a diagram illustrating an example of first and second detection intensity profiles of the image shown in FIG. 15A. FIG. [Figure 16] FIG. 3 is a diagram illustrating the positional relationship between first line-shaped pixels and second line-shaped pixels. [Figure 17] FIG. 2 is a diagram for explaining the arrangement of line-shaped pixels. [Figure 18A] 10 is a flowchart illustrating an example of an image generating method according to the second embodiment. [Figure 18B] 10 is a flowchart illustrating an example of a method for extracting a periodic structure pattern. [Figure 19A] FIG. 3 is a diagram illustrating an example of an image formed on a detection object. [Figure 19B] FIG. 19B is a diagram illustrating an example of a first detection intensity profile of the image shown in FIG. 19A. [Figure 19C] FIG. 19B is a diagram illustrating an example of a first average detected intensity profile of the image shown in FIG. 19A. [Figure 19D] FIG. 10 is a diagram illustrating the absolute value of the difference in detection intensity relative to the X coordinate. [Figure 19E] FIG. 4 is a diagram illustrating an example of a first detected intensity profile due to a non-periodic structure pattern. [Figure 20] 10 is a flowchart illustrating an example of an image generating method according to the third embodiment. [Figure 21] FIG. 10 is a view for explaining an example of a cross section of an image detector in the fourth embodiment. [Figure 22] FIG. 10 is a plan view of the fifth pixel layer and the sixth pixel layer as viewed from above in the Z direction. [Figure 23] 10 is a flowchart illustrating an example of an image generating method according to the fourth embodiment. [Figure 24A] FIG. 10 is a plan view of the fifth pixel layer and the sixth pixel layer as viewed from above in the Z direction, with the image detector rotated by a predetermined angle. [Figure 24B] FIG. 10 is a plan view of the fifth pixel layer and the sixth pixel layer as viewed from above in the Z direction, with the image detector rotated by a predetermined angle. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment will be described with reference to the drawings. (First embodiment) The imaging device of the embodiment is, for example, a transmission X-ray microscope. A transmission X-ray microscope is an imaging optical system that uses electromagnetic waves with short wavelengths and has a high resolution of approximately several tens of nanometers. Furthermore, because X-rays have high transmittance, it is possible to observe the surface structure and internal structure of a relatively thick specimen, such as a silicon wafer with semiconductor devices formed on its surface.

[0012] 1 is a schematic diagram illustrating an example of the configuration of an imaging device in the first embodiment. The imaging device includes a light source 11, an illumination mirror 12, an imaging mirror 13, and an image detector 14. The imaging device also includes a stage 22, a stage driver 23, and a control and analysis unit 31. The light source 11 is an X-ray source that generates X-rays by irradiating an electron beam onto a target made of molybdenum or the like. The illumination mirror 12 is used to focus the X-rays emitted from the light source 11 onto a specimen 41 placed on the stage 22. For example, a Monte Carlo mirror is used as the illumination mirror 12.

[0013] The test object 41 is, for example, a silicon wafer on which semiconductor devices are formed. FIG. 2 is a schematic diagram illustrating an example of the test object. The silicon wafer 41, which is the test object, has a plurality of memory chip corresponding regions 200 arranged in a matrix in a D1 direction and a D2 direction perpendicular to the D1 direction. The silicon wafer 41 is diced (die-cut) at the boundaries of the memory chip corresponding regions 200 to extract a plurality of memory chips. Various processes, such as depositing various films on the silicon wafer 41 using CVD technology or the like, injecting impurities into the various films using ion implantation technology, and patterning the deposited films using lithography and etching technology, are repeated to form a non-volatile memory in each of the plurality of memory chip corresponding regions 200.

[0014] The memory chip corresponding region 200 is composed of, for example, a memory cell array and peripheral circuits. FIG. 3 is a plan view illustrating an example of a memory cell array formed in the memory chip corresponding region 200. FIG. 3 shows an enlarged partial region of the memory cell array. Each block BLK included in the memory cell array is formed as a strip-shaped region with a predetermined width in the D2 direction and a longitudinal direction in the D2 direction. Slits ST are formed between each block BLK. The slits ST are filled with an insulating material to electrically isolate adjacent blocks BLK. Each block BLK includes multiple string units SU. The string units SU are formed as strip-shaped regions divided by the X-direction sides of the block BLK. Slits SHE are formed between each string unit SU. In this way, the memory cell array has a periodic structure with blocks BLK as units.

[0015] FIG. 4 is a plan view illustrating an example of a detailed structure of a memory cell array. FIG. 4 shows the structure of one block BLK, in which five string units SU0 to SU4 are configured, each including five select gate lines SGD0 to SGD4 separated by slits SHE. The slits SHE are filled with an insulating material, electrically isolating the select gate lines SGD between adjacent string units SU. Each string unit SU includes multiple NAND strings. Each NAND string is formed in a cylindrical memory hole MH extending in the Z direction. Multiple memory holes MH, each constituting a NAND string NS, are arranged in one string unit SU. Since the number of NAND strings (memory holes) in one string unit is extremely large, the memory holes MH are arranged in a staggered pattern to reduce chip size. Each memory hole MH in one string unit SU is connected to a bit line BL by a contact plug CP. Each bit line BL is connected to one memory hole MH per string unit SU via the contact plug CP. In order to connect each bit line BL to one memory hole MH of each string, the positions of the contact plugs CP are shifted in a direction perpendicular to the extension direction of the bit lines BL. The imaging device of the embodiment is used, for example, to observe the internal structure of a region where memory holes MH are formed, as shown in FIG.

[0016] In this embodiment, the silicon wafer 41 is placed on the stage 22, and the stage 22 is moved to a desired position, and an image is acquired by the image detector 14.

[0017] Returning to FIG. 1, the detailed configuration of the imaging device of the embodiment will be described. FIG. 5 is a diagram illustrating an example of a cross section of the image detector 14 in the first embodiment. The imaging mirror 13, which serves as an imaging optical member, focuses X-rays transmitted through the subject 41 and forms an image of the subject 41 on the detector 100 of the image detector 14. The image of the subject 41, which is disposed parallel to the D1-D2 plane, is formed on the XY plane of the detector 100. The optical axis of the X-rays is incident on the subject 41 along the D3 direction and on the detector 100 of the image detector 14 along the Z direction. The D3 direction is perpendicular to the D1-D2 plane. That is, the X direction of the detector 100 corresponds to the D1 direction of the subject 41, the Y direction of the detector 100 corresponds to the D2 direction of the subject 41, and the Z direction of the detector 100 corresponds to the D3 direction of the subject 41.

[0018] As shown in FIG. 5 , in this embodiment, the image detector 14 includes a substrate 130 and a detection element 100 having four pixel layers (a first pixel layer 140, a second pixel layer 150, a third pixel layer 160, and a fourth pixel layer 170). The first pixel layer 140 is formed on the substrate 130 made of silicon or the like. The first pixel layer 140 includes a plurality of first linear pixels 141. The surface of each of the first linear pixels 141 is covered with an insulating film 180 made of silicon oxide or the like. The second pixel layer 150 is formed above the first pixel layer 140. The second pixel layer 150 includes a plurality of second linear pixels 151. The surface of each of the second linear pixels 151 is covered with the insulating film 180.

[0019] The third pixel layer 160 is formed above the second pixel layer 150. The third pixel layer 160 includes a plurality of third linear pixels 161. The surface of each of the third linear pixels 161 is covered with an insulating film 180. The fourth pixel layer 170 is formed above the third pixel layer 160. The fourth pixel layer 170 includes a plurality of fourth linear pixels 171.

[0020] Fig. 6A is a plan view of the first pixel layer 140 seen from above in the Z direction. Fig. 6B is a plan view of the second pixel layer 150 seen from above in the Z direction. Fig. 6C is a plan view of the third pixel layer 160 seen from above in the Z direction. Fig. 6D is a plan view of the fourth pixel layer 170 seen from above in the Z direction. Note that the insulating film 180 is not shown in each of Figs. 6A to 6D. As shown in FIG. 6A, the first pixel layer 140 includes a plurality of first linear pixels 141 that extend in a direction that forms an angle θ1 with the X axis and have a length H when projected onto the Y axis. θ1 is usually set to a value smaller than π / 2. The plurality of first linear pixels 141 are arranged at equal intervals in the X direction. The plurality of first linear pixels 141 are arranged within a detection region 181 that has a size W in the X direction and a size H in the Y direction.

[0021] As shown in FIG. 6B, the second pixel layer 150 includes a plurality of second linear pixels 151 that extend in a direction that forms an angle θ2 with the X axis and have a length H when projected onto the Y axis. θ2 is usually set to a value greater than π / 2. The second linear pixels 151 are arranged at equal intervals in the X direction. Similar to the first linear pixels 141, the second linear pixels 151 are also arranged within a detection region 181 that has a size W in the X direction and H in the Y direction.

[0022] As shown in FIG. 6C , the third pixel layer 160 includes a plurality of third linear pixels 161 that extend in the direction that forms an angle θ3 with the Y axis and have a length W when projected onto the X axis. Typically, θ3 is set to a value smaller than π / 2. The plurality of third linear pixels 161 are arranged at equal intervals in the Y direction. The plurality of third linear pixels 161 are arranged at equal intervals in the X direction. Similar to the first linear pixels 141, the plurality of third linear pixels 161 are also arranged within a detection region 181 that has a size W in the X direction and H in the Y direction.

[0023] As shown in FIG. 6D, the fourth pixel layer 170 includes a plurality of fourth line-shaped pixels 171 that extend in a direction that forms an angle θ4 with the Y axis and have a length W when projected onto the X axis. Typically, θ4 is set to a value greater than π / 2. The plurality of fourth line-shaped pixels 171 are arranged at equal intervals in the Y direction. The plurality of fourth line-shaped pixels 171 are arranged at equal intervals in the X direction. Similar to the first line-shaped pixels 141, the plurality of fourth line-shaped pixels 171 are arranged within a detection region 181 that has a size W in the X direction and H in the Y direction.

[0024] As shown in FIG. 5, in the first pixel layer 140, a plurality of first linear pixels 141 are physically and electrically separated by an insulating film 180. In the second pixel layer 150, a plurality of second linear pixels 151 are physically and electrically separated by the insulating film 180. As shown in FIGS. 5 and 6C, in the third pixel layer 160, a plurality of third linear pixels 161 are physically and electrically separated by the insulating film 180. As shown in FIGS. 5 and 6D, in the fourth pixel layer 170, a plurality of fourth linear pixels 171 are physically and electrically separated by being arranged parallel to each other. Furthermore, as shown in FIG. 5, linear pixels arranged in adjacent layers (the first linear pixel 141 and the second linear pixel 151, the second linear pixel 151 and the third linear pixel 161, and the third linear pixel 161 and the fourth linear pixel 171) are physically and electrically separated by the insulating film 180.

[0025] For example, a superconducting nanostrip detector (superconducting single-photon detector) is used for the first line pixel 141, the second line pixel 151, the third line pixel 161, and the fourth line pixel 171. In this case, the width and thickness (length in the Z direction in FIG. 5) of each line pixel is determined so that the cross-sectional area of ​​the first line pixel 141, the second line pixel 151, the third line pixel 161, and the fourth line pixel 171 is reduced to an extent that a division of the superconducting region occurs.

[0026] Fig. 7 is a diagram showing the principle circuit configuration of the image detector 14 in this embodiment. More specifically, Fig. 7 shows the circuit configuration when a superconducting nanostrip detector is used. Fig. 7 shows one of a plurality of superconducting strips (first linear pixels) 141, and a current source 143, an amplifier 144, and a measuring instrument 145 corresponding to that one superconducting strip 141. As shown in FIG. 7 , one end of each superconducting strip 141 is grounded. The other end of the superconducting strip 141 is connected to a current source 143 and an amplifier 144. The current source 143 supplies a bias current Ib to the superconducting strip 141. The amplifier 144 amplifies the electrical signal generated in the superconducting strip 141 and transmits an output signal (electrical signal) to a measuring instrument 145. The measuring instrument 145 counts the pulse-shaped output signal (electrical signal) transmitted from the amplifier 144 when an X-ray photon is detected by the superconducting strip 141. The current source 143, the amplifier 144, and the measuring instrument 145 can also be provided outside the image detector 14. For example, the current source 143, the amplifier 144, and the measuring instrument 145 can also be configured to be provided within the control and analysis unit 31.

[0027] 8 is a diagram illustrating the principle of X-ray photon detection in a superconducting strip. First, the superconducting strip 141 is cooled to below its transition temperature using a refrigerator (not shown) to put it into a superconducting state. Then, a bias current Ib slightly below the critical current that maintains the superconducting state of the superconducting strip 141 is supplied from the current source 143. In this state, X-ray photons are incident on the superconducting strip 141.

[0028] At this time, the width and thickness of the superconducting strip 141 are formed to be about 50 to 500 nm, and the cross-sectional area of ​​the superconducting strip 141 is small. Therefore, when an X-ray photon is absorbed by the superconducting strip 141, a region (hot spot region) 51, which transitions to normal conduction and is called a hot spot, is formed in the superconducting region of the superconducting strip 141, as shown in Fig. 8. Since the electrical resistance of the hot spot region 51 increases, the bias current Ib bypasses the hot spot region 51 and flows in another region, a bypass region 52, as shown in Fig. 8.

[0029] When a current equal to or greater than the critical current flows through the detour region 52, the detour region 52 transitions to normal conduction, increasing its electrical resistance, and ultimately splitting the superconducting region of the superconducting strip 141. That is, the above-described split state (split state) of the superconducting region of the superconducting strip 141 occurs. After this, the hot spot region 51 and the detour region 52 that transitioned to normal conduction quickly disappear due to cooling, and a pulsed electrical signal is generated by the temporary electrical resistance caused by the splitting of the superconducting region of the superconducting strip 141. This pulsed electrical signal is amplified by the amplifier 144 and counted by the measuring instrument 145, thereby detecting the number of X-ray photons. The circuit configurations of the superconducting strip (second linear pixel) 151, the superconducting strip (third linear pixel) 161, and the superconducting strip (fourth linear pixel) 171, as well as the principle of detecting X-ray photons, are the same as those of the superconducting strip (first linear pixel) 141 described above. The number of X-ray photons for each of the superconducting strips 141 , 151 , 161 , and 171 counted by the measuring instrument 145 , that is, the detection result of the image detector 14 is output to the control and analysis unit 31 .

[0030] Most of the X-rays that reach the fourth linear pixels 171 pass through the fourth linear pixels 171, and some of them are absorbed and detected by the fourth linear pixels 171. In the third linear pixels 161, some of the X-rays that pass through the fourth linear pixels 171 or the insulating film 180 and reach the third linear pixels are absorbed and detected by the third linear pixels 161. Similarly, in the second linear pixels 151, some of the X-rays that pass through the third linear pixels 161 or the insulating film 180 and reach the second linear pixels are absorbed and detected by the second linear pixels 151. Similarly, in the first linear pixels 141, some of the X-rays that pass through the second linear pixels 151 or the insulating film 180 and reach the first linear pixels are absorbed and detected by the first linear pixels 141. Therefore, the intensities of X-rays that are uniformly irradiated onto the upper surface of the detection body 100 and detected by the first to fourth linear pixels may differ depending on the pixel layer.

[0031] Here, when the sum of the intensities detected at all of the fourth line-shaped pixels 171 arranged in the fourth pixel layer 170 is set to 1, the sum of the intensities detected in each pixel layer is expressed by the following value: That is, the sum of the intensities detected at all of the first line-shaped pixels 141 arranged in the first pixel layer 140 is set to 1 / k1, the sum of the intensities detected at all of the second line-shaped pixels 151 arranged in the second pixel layer 150 is set to 1 / k2, and the sum of the intensities detected at all of the third line-shaped pixels 161 arranged in the third pixel layer 160 is set to 1 / k3. In this case, by multiplying the intensity output from the first line-shaped pixels 141 by k1, the intensity output from the second line-shaped pixels 151 by k2, and the intensity output from the third line-shaped pixels 161 by k3, the intensities detected at the first, second, and third line-shaped pixels 141, 151, and 161 can be corrected to correspond to the intensity detected at the fourth line-shaped pixel 171. In the following description, the intensities detected at the first, second, and third line-shaped pixels 141, 151, and 161 are corrected by multiplying them by k1, k2, and k3, respectively, and are referred to as the "intensity" of each line-shaped pixel.

[0032] The control and analysis unit 31, which serves as an image processing unit, analyzes the signal (detection result) output from the image detector 14 and reconstructs an image (two-dimensional image) of the subject 41. The control and analysis unit 31 may be, for example, a personal computer equipped with a central processing unit (CPU) and memory (RAM). The operation of reconstructing the image of the subject 41 is performed in software, for example, by storing the program in advance in the memory and executing it on the CPU. The operation of reconstructing the image of the subject 41 may also be performed by one or more processors configured as hardware. For example, the processor may be configured as an electronic circuit, or may be a processor configured as an integrated circuit such as an FPGA (Field Programmable Gate Array). The control and analysis unit 31 also outputs a control signal to a stage driver 23 that moves the stage 22 in the D1 direction or the D2 direction.

[0033] Next, an image generating method using the above-mentioned imaging device will be described. First, the subject 41 is placed on the stage 22, and the subject 41 is moved so that X-rays are irradiated onto a region (observation region) of the structure to be observed. When X-rays are irradiated from the light source 11, an image of the observation region of the subject 41 is formed on the detection element 100 of the image detector 14. Then, signals (respective detection intensities) detected by the first line-shaped pixels 141, the second line-shaped pixels 151, the third line-shaped pixels 161, and the fourth line-shaped pixels 171 are output to the control / analysis unit 31. The control / analysis unit 31 reconstructs an image of the observation region of the subject 41 using the detection intensities of the first line-shaped pixels 141, the second line-shaped pixels 151, the third line-shaped pixels 161, and the fourth line-shaped pixels 171, and outputs the reconstructed image.

[0034] Here, a method for reconstructing an image of the subject 41 from the detection intensities of the first line-shaped pixels 141, the second line-shaped pixels 151, the third line-shaped pixels 161, and the fourth line-shaped pixels 171 will be described. FIG. 9 is a flowchart illustrating an example of an image generation method in the first embodiment. In the following description, an XY coordinate system is assumed with the center of the detection area 181 as the origin, and the position of each line of the first line-shaped pixels 141 and the second line-shaped pixels 151 is indicated by the X coordinate at the intersection of each line with the X axis. Furthermore, the position of each line of the third line-shaped pixels 161 and the fourth line-shaped pixels 171 is indicated by the Y coordinate at the intersection of each line with the Y axis.

[0035] FIG. 10A is a diagram illustrating an example of an image formed on a detection object. When a displacement point such as a defect exists in the specimen 41, a small area image corresponding to the displacement point appears in the image formed on the detection object 100, as shown in FIG. 10A. FIG. 10A shows an example in which the image formed on the detection object has a background of uniform optical intensity and two small area images PA and PB. The image generation method of this embodiment will be explained using an example in which the image formed on the detection object has two small area images PA and PB. Note that, to simplify calculations, the optical intensity of the background portion is assumed to be zero.

[0036] First, first and second detection intensity profiles are obtained using the detection object shown in FIGS. 5 and 6 (FIG. 9, S301). FIG. 10B is a diagram illustrating an example of the first and second detection intensity profiles of the image shown in FIG. 10A. The upper part of FIG. 10B is an example of the first detection intensity profile, and the lower part of FIG. 10B is an example of the second detection intensity profile. The detection intensity is obtained for each of the multiple first line-shaped pixels 141 arranged in the first pixel layer 140. The first detection intensity profile shown in the upper part of FIG. 10B is obtained by plotting the detection intensity against the X coordinate at the intersection of the line and the X axis. The detection intensity is obtained for each of the multiple second line-shaped pixels 151 arranged in the second pixel layer 150. The second detection intensity profile shown in the lower part of FIG. 10B is obtained by plotting the detection intensity against the X coordinate at the intersection of the line and the X axis.

[0037] Next, a combination of deformed portions of the first and second detection intensity profiles is determined (FIG. 9, S302). A deformed portion is a portion in the detection intensity profile where the detection intensity is higher than the intensity of the uniform background portion. In other words, it is a portion having a profile shape that is convex relative to the uniform background portion. As shown in FIG. 10A, two small area images PA and PB exist in the detection region 181. As a result, two deformed portions M11 and M12 exist in the first detection intensity profile shown in the upper part of FIG. 10B. Similarly, two deformed portions M21 and M22 exist in the second detection intensity profile shown in the lower part of FIG. 10B due to the small area images PA and PB. In S302, a combination of deformed portions M11 and M12 of the first detection intensity profile and deformed portions M21 and M22 of the second detection intensity profile that are due to the same small area image PA(PB) is determined.

[0038] Fig. 11A is a diagram illustrating the positional relationship between first line-shaped pixels and second line-shaped pixels. Fig. 11A shows several of the multiple first line-shaped pixels 141 arranged in the first pixel layer 140. Fig. 11A also shows second line-shaped pixels 151 whose X coordinates are the same as those of the first line-shaped pixels 141.

[0039] 11A, a point image QU is present at the top (top end in the Y direction) of one line of the multiple first linear pixels 141, and a point image QL is present at the bottom (bottom end in the Y direction) of the same first linear pixel 141a. That is, in the first pixel layer 140, both QU and QL are detected on the same line (first linear pixel 141a).

[0040] FIG. 11B is a diagram illustrating an example of the first and second detection intensity profiles. The upper part of FIG. 11B is an example of the first detection intensity profile, and the lower part of FIG. 11B is an example of the second detection intensity profile. The X coordinate of the deformation part of the first detection intensity profile due to the point image QU or QL is assumed to be xq (upper part of FIG. 11B). q includes the point image QU or the point image QL, and corresponds to the X coordinate at the intersection of the X axis and a straight line parallel to the line direction of the first linear pixel 141.

[0041] On the other hand, the point images QU and QL are detected on different lines in the second linear pixel 151. For example, the point image QU is detected by the second linear pixel 151a, and the point image QL is detected by the second linear pixel 151b. As shown in the lower part of FIG. 11B, the deformation portion of the second detection intensity profile due to the point image QU is x q +δ, the deformation part due to the point image QL is x q It appears at the X coordinate position of -δ, where δ is expressed by the following equation (1).

[0042] δ=H(1 / (2tanθ1)-1 / (2tanθ2)) …(1) formula In other words, if a point image is detected as a deformed portion at position x1 in the first detection intensity profile, the position (x2) where the same point image is detected as a deformed portion in the second detection intensity profile will be within the range of the following equation (2).

[0043] x1―δ<=x2<=x1+δ …Eq. (2) Returning to FIG. 10B, in the first detection intensity profile, the X coordinate of the center of gravity of the deformed portion M11 is x m11 Then, x m11can be calculated using the following equation (3).

[0044] x m11 =Σ(I1(x)x) / ΣI1(x) ... (3) In equation (3), I1(x) is the detected intensity of the first detected intensity profile, and the integration range is the X coordinate range of the deformation portion M11.

[0045] In the second detection intensity profile shown in the lower part of FIG. 10B, the X coordinate of the center of gravity of the deformed portion resulting from the same small area image as the deformed portion M11 is expressed as x1 in equation (2) plus x m11 is substituted. Furthermore, since the area of ​​the deformed portion of the detected intensity profile corresponds to the sum of the image intensities of the small region image, if the deformed portion of the first detected intensity profile and the deformed portion of the second detected intensity profile are caused by the same small region image, the area of ​​the deformed portion of the first detected intensity profile and the area of ​​the deformed portion of the second detected intensity profile will be the same. Here, there is variation in the intensities detected by the first line-shaped pixel 141 and the second line-shaped pixel 151, and there is also variation in the areas of the deformed portions of both. Whether they are the same or not is determined based on whether the areas of the deformed portions of both match within an error range estimated from the variation.

[0046] For example, the X coordinate x of the center of gravity of the deformed portion M11 in the first detection intensity profile m11 and the X coordinate x of the center of gravity of the deformed portion M21 in the second detection intensity profile. m21 satisfies the relationship of equation (2) and the areas of the deformed portions M11 and M21 can be considered to be the same, M11 and M21 are determined as a combination of deformed portions resulting from the same small region image. All combinations of deformed portions, such as the deformed portions M12 and M22, are determined to be identical, and combinations of deformed portions resulting from the same small region image are determined. In the case of the detection intensity profile shown in Figure 10B, by executing S302, two combinations are determined: a combination C121 of the deformed portions M11 and M21, and a combination C122 of the deformed portions M12 and M22.

[0047] FIG. 12A is a diagram illustrating another example of an image formed on a detection object. FIG. 12B is a diagram illustrating an example of first and second detection intensity profiles of the image shown in FIG. 12A. The upper part of FIG. 12B is an example of the first detection intensity profile, and the lower part of FIG. 12B is an example of the second detection intensity profile. FIG. 12C is a diagram illustrating an example of the third and fourth detection intensity profiles of the image shown in FIG. 12A. The left side of FIG. 12C is an example of the third detection intensity profile, and the right side of FIG. 12C is an example of the fourth detection intensity profile. As shown in FIG. 12A, when two small area images PC and PD exist within the detection area 181, as shown in the upper part of FIG. 12B, two deformation portions M1C and M1D are separated in the first detection intensity profile. In contrast, as shown in the lower part of FIG. 12B, they may overlap as in the deformation portion M2CD in the second detection intensity profile. In this case, the deformation portions M1C and M1D are regarded as a single deformation portion M1CD, and the deformation portions M1CD and M2CD are determined as a combination of deformation portions resulting from the same small area image.

[0048] Next, the center of gravity of the small region image is calculated (FIG. 9, S303). The X coordinate x of the center of gravity of the deformation part in the first detection intensity profile is calculated. 1p and the X coordinate x of the center of gravity of the deformation part in the second detection intensity profile. 2p From this, the coordinates of the center of gravity of the small area image (x 12p , y 12p That is, the coordinates of the center of gravity of the small area image are calculated using the following equations (4a) and (4b).

[0049] x 12p =(x 1p tanθ1-x 2p tanθ2) / (tanθ1-tanθ2) …(4a) formula y 12p =(x 1p -x 2p )tanθ1tanθ2 / (tanθ1-tanθ2) …(4b) formula In S303, for all combinations of the deformation portions of the first detection intensity profile and the second detection intensity profile determined in S302, the coordinates of the center of gravity of the small area image are calculated using equations (4a) and (4b). For example, for the combination C121 of the deformation portions M11 and M21, x 1p x m11 , x 2p x m21 By substituting these values ​​into equations (4a) and (4b), the center of gravity of the small area image (x m121 , y m121 ) is calculated. Similarly, for the other combination C122 determined in S302, the coordinates (x m122 , y m122 ) is calculated.

[0050] Next, third and fourth detection intensity profiles are obtained using the detection object shown in FIGS. 5 and 6 (FIG. 9, S304). FIG. 10C is a diagram illustrating an example of the third and fourth detection intensity profiles of the image shown in FIG. 10A. The left side of FIG. 10C is an example of the third detection intensity profile, and the right side of FIG. 10C is an example of the fourth detection intensity profile. The detection intensity is obtained for each of the multiple third line-shaped pixels 161 arranged in the third pixel layer 160. The third detection intensity profile shown on the left side of FIG. 10C is obtained by plotting the detection intensity against the Y coordinate at the intersection of the line and the Y axis. The detection intensity is obtained for each of the multiple fourth line-shaped pixels 171 arranged in the fourth pixel layer 170. The fourth detection intensity profile shown on the right side of FIG. 10C is obtained by plotting the detection intensity against the Y coordinate at the intersection of the line and the Y axis.

[0051] Next, a combination of the deformation portions of the third and fourth detection intensity profiles is determined (FIG. 9, S305). The combination determination method in S305 is the same as the combination determination method used in S302, but with the X coordinate replaced by the Y coordinate. For example, in the case of the detection intensity profile shown in FIG. 10C, by executing S305, two combinations are determined: a combination C341 of the deformation portion M31 and the deformation portion M41, and a combination C342 of the deformation portion M32 and the deformation portion M42.

[0052] Next, for all the combinations determined in S305, the coordinates of the center of gravity of the small region image are calculated (FIG. 9, S306). The Y coordinate y of the center of gravity of the deformed part in the third detection intensity profile is calculated. 3p and the Y coordinate y of the center of gravity of the deformation part in the fourth detection intensity profile. 4p From this, the coordinates of the center of gravity of the small area image (x 34p , y 34p ) can be obtained. The calculation of coordinates in S306 can be performed by using the formulas (4a) and (4b) obtained by replacing the X coordinate with the Y coordinate, the Y coordinate with the X coordinate, and θ1 with θ3 and θ2 with θ4. By executing S306, for example, for the combination C341 of the deformation portion M31 and the deformation portion M41, the barycentric coordinates (x m341 , y m341 ) is calculated. For the combination C342 of the deformation part M32 and the deformation part M42, the coordinates of the center of gravity of the small area image (x m342 , y m342 ) is calculated.

[0053] Next, a set of combinations of deformation portions of the detection intensity profiles is determined (FIG. 9, S307). That is, from the combination of the deformation portion of the first detection intensity profile and the deformation portion of the second detection intensity profile, and the combination of the deformation portion of the third detection intensity profile and the fourth detection intensity profile, a set of combinations in which the coordinates of the center of gravity position of the small area image and the area of ​​the deformation portion are the same is determined. S307 is a procedure for identifying deformation portions of the detection intensity profiles caused by the same small area image and linking them as a set.

[0054] Assume that in S302, two combinations, combination C121 (deformation portion M11 and deformation portion M21) and combination C122 (deformation portion M12 and deformation portion M22), are determined as combinations of the deformation portion of the first detection intensity profile and the deformation portion of the second detection intensity profile. Also, in S305, two combinations, combination C341 (deformation portion M31 and deformation portion M41) and combination C342 (deformation portion M32 and deformation portion M42), are determined as combinations of the deformation portion of the third detection intensity profile and the deformation portion of the fourth detection intensity profile. For example, if the coordinates (x m121 , y m121 ) and the coordinates of the center of gravity of combination C341 (x m341 , y m341 At this time, if the coordinates of the center of gravity positions of both images match within the range estimated from the position error and the error of the detection intensity, they are determined to be the same.

[0055] It is also determined whether the area of ​​the deformation portion included in combination C121 matches the area of ​​the deformation portion included in combination C341. If they match within the range of variation, they are determined to be identical. If it is determined that the coordinates of the center of gravity positions are identical and the areas of the deformation portions are also identical, combination C121 and combination C341 are determined to be set S1. In this case, the four deformation portions M11, M21, M31, and M41 are linked as being caused by the same small area image. Similarly, determination is made for other pairs of combinations, and sets are determined. For example, combination C122 and combination C342 are determined to be set S2.

[0056] FIG. 13A is a diagram illustrating another example of an image formed on a detection object. FIG. 13B is a diagram illustrating examples of first and second detection intensity profiles of the image shown in FIG. 13A. The upper part of FIG. 13B is an example of the first detection intensity profile, and the lower part of FIG. 13B is an example of the second detection intensity profile. FIG. 13C is a diagram illustrating examples of third and fourth detection intensity profiles of the image shown in FIG. 13A. The left side of FIG. 13C is an example of the third detection intensity profile, and the right side of FIG. 13C is a diagram illustrating an example of the fourth detection intensity profile. As shown in FIG. 13A, when two small area images PE and PF are arranged side by side in the X direction within the detection area 181, as shown in the upper part of FIG. 12B, two deformation portions M1E and M1F are separated in the first detection intensity profile. Furthermore, as shown in the lower part of FIG. 13B, two deformation portions M2E and M2F are also separated in the second detection intensity profile. 13C, in the third and fourth detection intensity profiles, deformations resulting from two small-area images may overlap and appear as a single deformation, such as deformations M3EF and M4EF. In this case, deformations M1E and M1F are considered together as a single deformation, and deformations M2E and M2F are considered together as a single deformation M2EF. Then, deformations M1EF, M2EF, M3EF, and M4EF are linked as a set of deformations resulting from the same small-area image.

[0057] Next, a small-area image is reconstructed (FIG. 9, S308). The four deformation sections associated with one set (deformation section for the first detection intensity profile, deformation section for the second detection intensity profile, deformation section for the third detection intensity profile, and deformation section for the fourth detection intensity profile) are used to reconstruct the small-area image using an existing method such as filtered back projection (FBP). If multiple sets are determined in S307, a small-area image is reconstructed for each set. FIGS. 14A and 14B are diagrams illustrating an example of a reconstructed small-area image. FIG. 14A shows a small-area image R1 reconstructed using the above-mentioned set S1. FIG. 14B shows a small-area image R2 reconstructed using the above-mentioned set S2. In this case, the area of ​​the small area image R1 or the small area image R2 is determined as the smallest X or Y coordinate area that includes the deformed portion of the first detected intensity profile, the deformed portion of the second detected intensity profile, the deformed portion of the third detected intensity profile, and the deformed portion of the fourth detected intensity profile that belong to the set S1 or S2.

[0058] Finally, an image obtained by superimposing all the small region images reconstructed in S308 is output as an image formed on the detection object 100 (FIG. 9, S309). This completes the series of procedures related to the image generation method of the first embodiment. FIG. 14C is a diagram illustrating an example of a reconstructed image. Since the first to fourth detection intensity profiles described above are all discrete data on the X coordinate or Y coordinate, the reconstructed image is a detection intensity distribution at points arranged at equal intervals in the X and Y directions.

[0059] In the above description, the background intensity is assumed to be zero, but if there is background intensity, the same processing is performed using a detection intensity profile from which the background intensity has been subtracted, and the image is calculated by adding the background intensity to the small region image obtained in S309. In this case, the intensity of the deformed part of the detection intensity profile may be lower than the intensity of the background part, and the detection intensity profile of the deformed part may become concave.

[0060] In image reconstruction using FBP or the like, the larger the area of ​​the image to be reconstructed and the fewer the number of line directions, the higher the possibility that an image different from the actual image, called architecture, will be included. Therefore, for example, in order to obtain an image faithful to the actual image using the method shown in Patent Document 2, it is necessary to increase the number of line directions. In other words, the angle θ between the line-shaped pixels and the X axis (Y axis) m This may increase the number of pixel layers with different angles (m is an integer of 1 or more), which may make it extremely difficult to manufacture the image detector. For example, if linear pixels with angles to the X-axis that vary in 15-degree increments are used, linear pixels parallel to 12 different directions, θ = 0, 15, 30, 45, 60, 75, 90, 105, 120, 135, 150, and 165, are required. In this case, the number of line directions is 12, and the detection body 100 requires 12 pixel layers.

[0061] In contrast, in the imaging device of this embodiment, a set of deformation portions of the first to fourth detection intensity profiles is determined, and a small area image is reconstructed in each of the smallest XY coordinate areas including the deformation portions of the obtained set. The small area images reconstructed in each area are superimposed to obtain an image formed on the detection object 100 (an image of the entire detection area 181). Because the reconstruction is performed in an area smaller than the detection area 181, it is possible to output an image that is faithful to the actual image even with a small number of line directions. In other words, it is possible to obtain a highly accurate reconstructed image while simplifying the manufacture of the image detector.

[0062] Finally, we will explain how to determine the line directions of the first to fourth linear pixels 141, 151, 161, and 171. If θ1=π-θ2, θ3=π-θ4, and θ1=θ3, θ2=θ4, an image that is uniformly resolved in the X and Y directions is reconstructed. Below, we will explain how to determine θ1 to θ4 for this case.

[0063] FIG. 15A is a diagram illustrating another example of an image formed on a detection object. FIG. 15B is a diagram illustrating an example of the first and second detection intensity profiles of the image shown in FIG. 15A. The upper part of FIG. 15B is an example of the first detection intensity profile, and the lower part of FIG. 15B is an example of the second detection intensity profile. As shown in FIG. 15A, two circular small area images PG and PH having the same diameter and image intensity are arranged in the X direction. The distance between the small area images PG and PH is defined as L. GH Let's say.

[0064] As shown in FIG. 15B, two deformation portions M13 and M14 appear in the first detection intensity profile. Two deformation portions M23 and M24 also appear in the second detection intensity profile. The range r201 of the center of gravity of the deformation portion on the second detection profile that is caused by the same small area image as the deformation portion M13 in the first detection intensity profile can be obtained by equation (2). As shown in the lower part of FIG. 15B, the center of gravity x m23 Also, the center of gravity position x of the deformed part M24 m24 When both are included in the range r201, it is not possible to determine whether the deformation part M23 or M24 is caused by the same small area image as the deformation part M13. GH In the above cases, it is impossible to determine the combination of deformation parts. <L GH Using the relationship θ1=π-θ2 and equation (1), the following relationship (5) holds.

[0065] θ1>tan -1 (H / L GH ) …(5) formula On the other hand, since the detection intensity profile is not continuous data but discrete data, there are errors due to grid errors. FIG. 16 is a diagram illustrating the positional relationship between the first line-shaped pixels and the second line-shaped pixels. FIG. 16 shows several of the multiple first line-shaped pixels 141 arranged in the first pixel layer 140. FIG. 16 also shows second line-shaped pixels 151 whose X coordinates are equal to those of these first line-shaped pixels 141. As shown in FIG. 16, assuming that a point image QA exists, in the first detection intensity profile, x=x 1QA, and in the second detection intensity profile, x=x 2QA A deformed part corresponding to the point image QA is detected at the position. The range of the point image QA detected as the same x coordinate in the first and second detection intensity profiles is shown in the region (R202) surrounded by a thick dashed line. This region R202 is the area where the grid error (G x , G y ) is shown. G x is the length of the diagonal line in the X direction of the diamond-shaped region R202. y is the length of the diagonal line in the Y direction of the region R202. The line pitch of the first line-shaped pixels 141 and the line pitch of the second line-shaped pixels 151 are the same (=L P ), the grid error can be calculated using the following equations (6a) and (6b).

[0066] G x =L P / sinθ1…(6a) G y =L P / cosθ1…(6b) formula θ1 is usually set to around π / 2, so G x From G y G y In order to reduce θ1, it is desirable to make it as small as possible (in the direction approaching 0 from π / 2). The minimum pattern size that can be observed with the imaging device shown in Figure 1 is L min Then, normally L min <L GH Therefore, the equation (5) is satisfied and θ1 is smallest when θ1=tan -1 (H / L min ) The resolution of the detector (the smallest detectable unit) is usually determined by the smallest observable pattern size (L min The resolution of the image detector in the X direction is determined to be 1 / 2 to 1 / 10 of G x and L min G x 2 to 10 times, and θ1=tan -1 (H / L min), it is desirable that the angle (π-2θ1) formed by the first linear pixel 141 and the second linear pixel 151 is within a range that satisfies the following formula (7).

[0067] 2sin -1 (2L p / H)<=π-2θ1<=2sin -1 (10L p / H) …(7) formula As described above, according to the imaging device of this embodiment, the detection body 100 of the image detector 14 has four pixel layers (first to fourth pixel layers 140, 150, 160, and 170). A plurality of linear pixels (first to fourth linear pixels 141, 151, 161, and 171) are arranged in each of the first to fourth pixel layers 140, 150, 160, and 170, and the linear directions of the linear pixels in each layer are different from each other. A set of deformations resulting from the same small region image is determined for a first detection intensity profile obtained from the first linear pixels 141, a second detection intensity profile obtained from the second linear pixels 151, a third detection intensity profile obtained from the third linear pixels 161, and a fourth detection intensity profile obtained from the fourth linear pixels 171. For each set, a small region image is reconstructed using the associated multiple deformations. A reconstructed image of the entire detection region 181 is generated by superimposing all the obtained small region images.

[0068] Since the reconstruction is performed in an area smaller than the detection area 181, the angle θ between the line-shaped pixels and the X axis (Y axis) m It is possible to obtain a highly accurate reconstructed image with a small number of pixel layers without using many pixel layers with different characteristics. That is, it is possible to obtain a highly accurate reconstructed image while simplifying the manufacture of the image detector. Furthermore, since it is not necessary to rotate the subject 41 when obtaining the intensity distribution, no positional deviation (deviation of the rotation axis) occurs when the subject 41 is rotated, and therefore a more accurate reconstructed image can be generated.

[0069] It is also possible to omit the fourth linear pixel 171. In this case, the line direction θ3 of the third linear pixel 161 becomes π / 2. Although only the Y coordinate can be identified for the deformed portion of the third detection profile, in the case of a sparse pattern in which at least one small area image exists on the third linear pixel 161, a reconstructed image can be acquired with sufficient accuracy. With such a configuration, the number of pixel layers can be reduced to three, further simplifying the manufacture of the image detector 14 and reducing manufacturing costs.

[0070] In addition to the line pixels in the four directions described above, it is also possible to add line pixels numbered 5, 6, ..., 2n-1, and 2n (where n is an integer equal to or greater than 3). Here, the first and second line pixels 141 and 151 are defined as the first pair, the third and fourth line pixels 161 and 171 as the second pair, the fifth and sixth line pixels as the third pair, ..., 2n-1, and 2n line pixels as the nth pair. In this case, when viewed from above in the Z direction, it is desirable to arrange each pair evenly in the rotational direction around the center of the detection area 181 as the axis. FIG. 17 is a diagram illustrating the arrangement of line pixels. As shown in FIG. 17, where i is an integer equal to or less than n, it is desirable that the angle between the 2(i-1) line pixel 203 and the 2i line pixel 204 and the angle between the 2i-1 line pixel 205 and the 2i+1 line pixel 206 are each π / n.

[0071] For example, when n=3, that is, when two line pixels in different directions are added and the first to sixth line pixels are arranged on the detector 100, it is desirable to determine the line direction of the six line pixels so that the angle between the first line pixel and the third line pixel, the angle between the second line pixel and the fourth line pixel, the angle between the third line pixel and the fifth line pixel, and the angle between the fourth line pixel and the sixth line pixel are each π / 3=60 degrees. By adding line pixels in this way, it is possible to obtain a reconstructed image with even higher accuracy.

[0072] The above embodiment is based on the assumption of a transmission X-ray microscope, but anything that can acquire an image of the subject 41 may be used. (Second embodiment) Next, a second embodiment will be described. The structure of the imaging device of the second embodiment is the same as that of the first embodiment described above. The second embodiment differs from the first embodiment described above in the method of reconstructing an image of the subject 41 from the first to fourth detection intensity profiles (image generation method). The same components as those in the first embodiment are denoted by the same reference numerals and description thereof will be omitted. Below, differences from the first embodiment will be described.

[0073] Fig. 18A is a flowchart illustrating an example of an image generating method in the second embodiment. Fig. 19A is a diagram illustrating an example of an image formed on a detection object. As shown in Fig. 19A, the case where a portion of the image of the periodic structure pattern is deformed and a small area image PJ exists as an image formed on the detection object 100 will be described below. First, a first detection intensity profile, a second detection intensity profile, a third detection intensity profile, and a fourth detection intensity profile are obtained (S401).

[0074] FIG. 19B is a diagram illustrating an example of a first detected intensity profile of the image shown in FIG. 19A. Next, a detected intensity profile (periodic structure profile) included in the first detected intensity profile and the second detected intensity profile and attributed to a periodic structure pattern is extracted. FIG. 18B is a flowchart illustrating an example of a method for extracting a periodic structure pattern. The period TX in the X direction of the observation area of ​​the object 41 is obtained from design data. Alternatively, Fourier analysis of the first and second detected intensity profiles may be performed to obtain the period TX using a period corresponding to a Fourier component that is present in both the first and second detected intensity profiles and exhibits maximum intensity, etc. (S451). The X coordinate of the first detected intensity profile (DR1) is divided into N blocks, each with a period TX, and N average profiles (DB1A) of the detected intensity profiles (DB11, DB12, . . . , DB1N) of each block are arranged in the X direction to create a first average detected intensity profile (DA1) (S452). FIG. 19C is a diagram illustrating an example of a first average detected intensity profile of the image shown in FIG. 19A. Next, the difference between the first average detected intensity profile (DA1) and the first detected intensity profile (DR1) is calculated. Figure 19D shows the absolute value of the detected intensity difference with respect to the X coordinate. It is determined whether any absolute value of the difference exceeds a predetermined tolerance (TH). If the result is Yes, proceed to S455 (S453). If the result is No, the block (DB1X) whose absolute value of the difference exceeds the tolerance is excluded, and the average profile of the detected intensity profiles of the remaining blocks is calculated. N of the obtained average profiles are arranged in the X direction to create a first average detected intensity profile, and then the process returns to S453 (S454). The finally obtained first average intensity profile is determined as the first periodic structure profile (S455). Similarly, a second periodic structure profile is extracted from the second detected intensity profile. If the sum of the areas and the center of gravity of the deformed portions of the obtained second periodic structure profile match within the range of variation and the sum of the areas and the center of gravity of the deformed portions of the first periodic structure profile, the two are considered to be periodic structure profiles resulting from the same periodic structure pattern.Then, the first periodic structure profile is subtracted from the first detected intensity profile to obtain a first detected intensity profile due to the aperiodic structure pattern (first aperiodic structure profile), and the second periodic structure profile due to the same periodic structure pattern as the first periodic structure profile is subtracted from the second detected intensity profile to obtain a second aperiodic structure profile (S402).

[0075] 19E is a diagram illustrating an example of a first detection intensity profile due to a non-periodic structure pattern. By the procedure of S402, it is possible to obtain a detection intensity profile in which only the deformation portion due to the non-periodic structure pattern present in the observation region of the subject 41 is extracted, as shown in FIG.

[0076] Next, in S402, the first detected intensity profile, first average detected intensity profile, and first periodic structure profile are replaced with the third detected intensity profile, third average detected intensity profile, and third periodic structure profile, and the second detected intensity profile, second average detected intensity profile, and second periodic structure profile are replaced with the fourth detected intensity profile, fourth average detected intensity profile, and fourth periodic structure profile, thereby extracting the third detected intensity profile (third periodic structure profile) and fourth detected intensity profile (fourth periodic structure profile) contained in the third detected intensity profile and the fourth detected intensity profile that are caused by the periodic structure pattern. If the sum of the areas and the center of gravity of the deformed portions of the obtained third or fourth periodic structure profile match the sum of the areas and the center of gravity of the deformed portions of the first or second periodic structure pattern within the range of variation, the third and fourth periodic structure profiles are considered to be caused by the same periodic structure pattern as the first and second periodic structure profiles. A third detected intensity profile due to the non-periodic structure pattern is obtained by subtracting a third periodic structure profile resulting from the same periodic structure pattern as the first and second periodic structure patterns from the third detected intensity profile, and a fourth detected intensity profile (fourth non-periodic structure profile) is obtained by subtracting a fourth periodic structure profile resulting from the same periodic structure pattern as the first and second periodic structure patterns from the fourth detected intensity profile (S403).

[0077] Next, an image of the periodic structure pattern is reconstructed by the FBP method or the like using the first to fourth periodic structure profiles resulting from the same periodic structure pattern (S404). Furthermore, a small area image of the non-periodic structure pattern is reconstructed using the first to fourth non-periodic structure profiles (S405). S405 is performed using the series of steps shown in Fig. 9. However, the first to fourth detection intensity profiles in the steps of Fig. 9 are replaced with the first to fourth non-periodic structure profiles, respectively.

[0078] Finally, the image of the periodic structure pattern reconstructed in S404 is superimposed on the small region image reconstructed in S405. The superimposed image is output as an image formed on the detection object 100 (S406). This completes the series of steps related to the image generation method of the second embodiment.

[0079] In the first embodiment, when the object 41 has a dense periodic structure pattern as shown in FIG. 4, the deformed portions often overlap each other. This makes it impossible to distinguish the deformed portions, and there is a possibility that a reconstructed image different from the actual image will be output. In contrast, in the second embodiment, the detected intensity profile due to the periodic structure pattern is excluded, so that the detected intensity profile due to the sparse non-periodic structure pattern can be extracted. Therefore, even when a dense periodic structure pattern is formed on the object 41, a reconstructed image can be obtained with high accuracy. (Third embodiment) Next, a third embodiment will be described. The structure of the imaging device of the third embodiment is the same as that of the second embodiment described above. The third embodiment differs from the second embodiment described above in the method of reconstructing an image of the subject 41 from the first to fourth detection intensity profiles (image generation method). The same components as those in the second embodiment are denoted by the same reference numerals and will not be described again. Below, differences from the second embodiment will be described.

[0080] FIG. 20 is a flowchart illustrating an example of an image generating method according to the third embodiment. First, a first detection intensity profile, a second detection intensity profile, a third detection intensity profile, and a fourth detection intensity profile are obtained (S501). Next, an image formed on the detection object 100 is calculated using design data of the observation area of ​​the subject 41 by an imaging simulator or the like. As a result, first to fourth simulated detection intensity profiles corresponding to the first to fourth detection intensity profiles are created (S502). Next, the first simulated detection intensity profile is subtracted from the first detection intensity profile, the second simulated detection intensity profile is subtracted from the second detection intensity profile, the third simulated detection intensity profile is subtracted from the third detection intensity profile, and the fourth simulated detection intensity profile is subtracted from the fourth detection intensity profile (S503). The profiles generated by S503 are referred to as first to fourth differential detection intensity profiles.

[0081] Next, an image based on the design data is reconstructed by the FBP method or the like using the first to fourth simulated detection intensity profiles (S504). Note that if an image calculated by the simulation in S501 is used, S504 can be omitted.

[0082] Furthermore, the first to fourth difference detection intensity profiles are used to reconstruct a small area image that is a difference portion from the design data (S505). S505 is performed using the series of steps shown in Fig. 9. However, the first to fourth detection intensity profiles in the steps of Fig. 9 are replaced with the first to fourth difference detection intensity profiles, respectively.

[0083] Finally, the image based on the reconstructed design data in S504 (or the image calculated by simulation based on the design data in S501) is superimposed on the small region image representing the difference from the reconstructed design data in S505. The superimposed image is output as an image formed on the detection object 100 (S506). This completes the series of steps related to the image generation method of the third embodiment.

[0084] According to this embodiment, by subtracting the simulated detection intensity profile from the detection intensity profile, only the difference between the actual image and the image predicted by the simulation is extracted. This makes it possible to reconstruct a sparse image with fewer overlapping deformations in the difference detection intensity profile. Therefore, a highly accurate reconstructed image can be obtained. (Fourth embodiment) Next, a fourth embodiment will be described. While the image detector of the first embodiment has a structure consisting of four layers, namely, a first pixel layer, a second pixel layer, a third pixel layer, and a fourth pixel layer, the structure of this embodiment has a structure consisting of two layers, namely, a fifth pixel layer 210 and a sixth pixel layer 220, as shown in FIG. 21. FIG. 21 is a diagram illustrating an example of a cross section of the image detector of the fourth embodiment. FIG. 22 is a plan view of the fifth pixel and the sixth pixel layer as viewed from above in the Z direction. FIG. 22 shows the sixth pixel layer on the upper side and the fifth pixel layer on the lower side. As shown in the lower side of FIG. 22, the fifth pixel layer 210 has fifth linear pixels 211 extending in the Y direction, arranged at equal intervals in the X direction. As shown in the upper side of FIG. 22, the sixth pixel layer 220 has sixth linear pixels 221 extending in the X direction, arranged at equal intervals in the Y direction. The sixth pixel layer 220 is further provided with a rotation mechanism 24 that rotates around an axis in the Z direction, centered on the center 183 of the detection region 182. Note that while the detection area 181 of the image detector 14 in the first embodiment is rectangular, the detection area 182 of the image detector 15 in the fourth embodiment is circular so that the same image can be detected even when rotated. The same components as in the first embodiment are given the same reference numerals and their description will be omitted. Below, differences from the first embodiment will be described.

[0085] FIG. 23 is a flowchart illustrating an example of an image generating method according to the fourth embodiment. Also, FIGS. 24A and 24B are plan views of the fifth and sixth pixel layers viewed from above in the Z direction with the image detector rotated by a predetermined angle. First, as shown in FIG. 24A, the image detector 15 is rotated around the Z direction as an axis 183 using the rotation mechanism 24 so that the angle between the fifth linear pixel 211 and the X axis and the angle between the sixth linear pixel 221 and the Y axis are θ5 (S601). In this state, detected intensity profiles are obtained at the fifth linear pixel 211 and the sixth linear pixel 221 (S602). At this time, the detected intensity profile obtained at the fifth linear pixel 211 corresponds to the first detected intensity profile, and the detected intensity profile obtained at the sixth linear pixel 221 corresponds to the third detected intensity profile. Next, as shown in FIG. 24B, the image detector 15 is rotated so that the angle between the fifth line pixel 211 and the X axis and the angle between the sixth line pixel 221 and the Y axis become θ6 (S603). In this state, detection intensity profiles are acquired at the fifth line pixel 211 and the sixth line pixel 221 (S604). At this time, the detection intensity profile acquired at the fifth line pixel 211 corresponds to the second detection intensity profile, and the detection intensity profile acquired at the sixth line pixel 221 corresponds to the fourth detection intensity profile. Using the obtained detection intensity profiles corresponding to the first, second, third, and fourth detection intensity profiles, an image is output in which all small region images reconstructed in the same manner as in the first embodiment are synthesized (S605). This completes the series of procedures related to the image generation method of the fourth embodiment. In the above description, detection intensity profiles corresponding to the first, second, third, and fourth detection intensity profiles are obtained by rotating the image detector 15, but this can also be achieved by rotating the subject 41 around the axis in the D3 direction, with the position corresponding to the center of the detection area 182 as the center.

[0086] According to this embodiment, by rotating the image detector having two pixel layers, it is possible to reduce the number of layers of the image detector and simplify the manufacture of the image detector. In addition, since the rotation angle is small, it is possible to reduce misalignment due to rotation.

[0087] Although several embodiments of the present invention have been described, these embodiments are presented by way of example only and are not intended to limit the scope of the invention. These novel embodiments may be embodied in various other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0088] 11...light source, 12...illumination mirror, 13...imaging mirror, 14...image detector, 22...stage, 23...stage drive unit, 31...control analysis unit, 41...object to be inspected, 100...detected body, 140...first pixel layer, 141...first line-shaped pixel (superconducting strip), 150...second pixel layer, 151...second line-shaped pixel, 160...third pixel layer, 161...third line-shaped pixel, 170...fourth pixel layer, 171...fourth line-shaped pixel

Claims

1. a stage for holding a subject; a detector including a first pixel layer, a second pixel layer, and a third pixel layer stacked in this order with an insulating film interposed therebetween; an imaging optical member that forms an image of the imaging light transmitted through the subject on a detector of the detector; an image processing unit that reconstructs an image of the subject from a detection intensity that is the intensity of the imaging light detected by the detector, the first pixel layer includes a plurality of first linear pixels having linear light receiving surfaces extending in a first direction, the plurality of first linear pixels being arranged at equal intervals in a plane parallel to the first pixel layer; the second pixel layer includes a plurality of second linear pixels having linear light receiving surfaces extending in a second direction, the plurality of second linear pixels being arranged at equal intervals in a plane parallel to the second pixel layer; the third pixel layer includes a plurality of third linear pixels having linear light receiving surfaces extending in a third direction, the plurality of third linear pixels being arranged at equal intervals in a plane parallel to the third pixel layer; the first direction, the second direction, and the third direction are different from each other, the detector outputs a first detected intensity profile, which is the detected intensities detected in the first pixel layer, a second detected intensity profile, which is the detected intensities detected in the second pixel layer, and a third detected intensity profile, which is the detected intensities detected in the third pixel layer; The image processing unit extracting one or more first deformation portions from the first detected intensity profile, extracting one or more second deformation portions from the second detected intensity profile, and extracting one or more third deformation portions from the third detected intensity profile; creating one or more sets of deformation sections each including one of the first deformation sections, one of the second deformation sections, and one of the third deformation sections; reconstructing a small region image for each of the sets of deformation units based on the first to third deformation units included in each of the sets of deformation units; an imaging device that generates an image of the subject by superimposing all of the reconstructed small area images;

2. the detector further includes a fourth pixel layer, and outputs a fourth detected intensity profile, which is the detected intensity detected in the fourth pixel layer; the fourth pixel layer includes a plurality of fourth linear pixels having linear light receiving surfaces extending in a fourth direction, the plurality of fourth linear pixels being arranged at equal intervals in a plane parallel to the fourth pixel layer; the fourth direction is different from any of the first direction, the second direction, and the third direction, The image processing unit extracting one or more fourth deformations from the fourth detected intensity profile; generating one or more first deformation unit pairs each consisting of one of the first deformation units and one of the second deformation units, and generating one or more second deformation unit pairs each consisting of one of the third deformation units and one of the fourth deformation units; For each of the first deformation portion pairs, first barycentric coordinates of the original first small region image are calculated; For each of the second deformation portion pairs, second barycentric coordinates of the second small region image serving as an origin are calculated; the deformation unit set is created by the first deformation unit, the second deformation unit, the third deformation unit, and the fourth deformation unit, which are included in the first deformation unit pair and the second deformation unit pair, and whose first and second barycentric coordinates are substantially equal to each other; The imaging device according to claim 1 .

3. 3. The imaging device according to claim 2, wherein the fourth direction is set so that a first included angle formed between the first direction and the second direction is equal to a second included angle formed between the third direction and the fourth direction.

4. The image processing unit extracting a first periodic structure profile common to the first detected intensity profile and the second detected intensity profile; subtracting the first periodic structure profile from the first detected intensity profile and the second detected intensity profile to generate a first subtraction profile and a second subtraction profile; extracting a second periodic structure profile common to the third detected intensity profile and the fourth detected intensity profile; subtracting the second periodic structure profile from the third detected intensity profile and the fourth detected intensity profile to generate a third subtraction profile and a fourth subtraction profile; reconstructing the small-area image using the first to fourth subtraction profiles; reconstructing a periodic image using the first periodic structure profile and the second periodic structure profile; The imaging apparatus according to claim 2 , wherein an image of the subject is generated by superimposing all of the reconstructed small-area images and the periodic image.

5. a first pixel layer, a second pixel layer, and a third pixel layer are stacked in this order with an insulating film interposed therebetween, the first pixel layer including a plurality of first linear pixels having linear light receiving surfaces extending in a first direction and arranged at equal intervals in a plane parallel to the first pixel layer, the second pixel layer including a plurality of second linear pixels having linear light receiving surfaces extending in a second direction and arranged at equal intervals in a plane parallel to the second pixel layer, and the third pixel layer including a plurality of third linear pixels having linear light receiving surfaces extending in a third direction and arranged at equal intervals in a plane parallel to the third pixel layer, extracting one or more first deformation portions from the first detected intensity profile, extracting one or more second deformation portions from the second detected intensity profile, and extracting one or more third deformation portions from the third detected intensity profile; creating one or more sets of deformation sections each including one of the first deformation sections, one of the second deformation sections, and one of the third deformation sections; reconstructing a small region image for each of the sets of deformation units based on the first to third deformation units included in each of the sets of deformation units; an image generating method for generating an image of the object by superimposing all of the reconstructed small area images;

6. An imaging device for detecting an arbitrary image, A linear pixel array is provided within a detection area, the line directions of the linear pixel array are at least three directions, namely, a first line direction, a second line direction, and a third line direction, the first line direction and the second line direction are not more than the number of the line directions minus one, and are arranged on either side of a first equal division direction, which is one of the directions (equal division directions) that equally divide a rotation direction about an axis of the center by two or more straight lines passing through the center of the detection area, and the angle of the third line direction with respect to a second equal division direction that is different from the first equal division direction is not more than the angle formed by the first equal division direction and the first line direction; a function of acquiring a first detected intensity profile by the linear pixel array in the first line direction, a second detected intensity profile by the linear pixel array in the second line direction, and a third detected intensity profile by the linear pixel array in the third line direction; extracting a first deformation portion present in a part of the first detected intensity profile, extracting a second deformation portion of the second detected intensity profile and a third deformation portion of the third detected intensity profile from a small area image in the detection area corresponding to the first deformation portion of the first detected intensity profile, and reconstructing the small area image from a combination of the first deformation portion of the first detected intensity profile, the second deformation portion of the second detected intensity profile, and the third deformation portion of the third detected intensity profile, An imaging device having a mechanism for outputting an image in which all of the reconstructed small area images are superimposed.

7. The imaging device of claim 6, wherein the angle between the first line direction and the second line direction is greater than or equal to twice the arc sine of the value obtained by dividing twice the line pitch of the line-shaped pixels by the width of the detection area in an angular direction that is half the angle between the first line direction and the second line direction, and is less than or equal to twice the arc sine of the value obtained by dividing ten times the line pitch of the line-shaped pixels by the width of the detection area in a straight line direction that is half the angle between the line direction and the second line direction.

8. a function of acquiring a fourth detection intensity profile by the linear pixel array in a fourth line direction that is different from the first line direction, the second line direction, and the third line direction; 7. The imaging device according to claim 6, further comprising a function of extracting the first deformed portion present in a portion of the first detected intensity profile, extracting the second deformed portion of the second detected intensity profile, the third deformed portion of the third detected intensity profile, and the fourth deformed portion of the fourth detected intensity profile from the small area image in the detection area corresponding to the first deformed portion of the first detected intensity profile, and reconstructing the small area image from a combination of the first deformed portion of the first detected intensity profile, the second deformed portion of the second detected intensity profile, the third deformed portion of the third detected intensity profile, and the fourth detected intensity profile.

9. 7. The imaging device according to claim 6, further comprising a function of extracting a periodic structure common to the first detected intensity profile and the second detected intensity profile, subtracting the periodic structure from the first detected intensity profile and the second detected intensity profile, reconstructing the small region image using the first and second detected intensity profiles from which the periodic structure has been subtracted, and outputting an image superimposed on the reconstructed image of the periodic structure.

Images