JP2005055265A - X-ray analysis apparatus, X-ray analysis method, and surface inspection apparatus - Google Patents

Abstract

An X-ray analyzer capable of analyzing a wide range of elements is configured in a small size.
An X-ray tube 61 selectively generates three different types of X-rays. The spectroscopic element switching mechanism switches the positions of the double curved spectroscopic elements 80a, 80b, and 80c in accordance with the type of X-ray generated by the X-ray tube 61. The crystal surface of the double-curved spectroscopic element is concavely curved with a predetermined curvature R1 in the vertical direction, and X-rays incident at a Bragg angle with a predetermined spread are reflected on the crystal surface of the double-curved spectroscopic element. Bragg reflection results in monochromatic X-rays. The crystal surface of the double-curved spectroscopic element is curved in a concave shape with a predetermined curvature R2 in the lateral direction. Due to the curvature R 1 and the curvature R 2, X-rays that are monochromatic by Bragg reflection on the crystal surface of the double curved spectroscopic element are focused in a spot shape on the surface of the semiconductor wafer 1.
[Selection] Figure 3

Description

  The present invention relates to an X-ray analysis apparatus and an X-ray analysis method suitable for inspection of foreign matters attached to the surface of an inspection object such as a semiconductor wafer, a liquid crystal substrate, and a magnetic disk, and a surface inspection apparatus using them.

  In the manufacturing process of semiconductor devices, liquid crystal display devices, magnetic disks, etc., the surface of a semiconductor wafer, liquid crystal substrate, magnetic disk, or substrate (substrate), etc. is inspected for defects such as scratches and adhesion of foreign matter. Is called. In general, as a surface inspection apparatus for inspecting defects on the surface of an object to be inspected, a scattered light detection method or a reflection method for irradiating the surface of the object to be inspected and detecting scattered light or reflected light from the surface of the object to be inspected. A device using a light detection method is known (Patent Document 1). The scattered light detection method and the reflected light detection method are suitable for measuring the shape and size of defects on the surface of the inspection object. Also, using an interference phase detection method that divides the inspection light and irradiates the reference surface and the surface of the inspection object, and detects the interference between the reflected light from the reference surface and the reflected light from the surface of the inspection object (Patent Document 2). The interference phase detection method is suitable for measuring the height and depth of defects on the surface of the inspection object. Some surface inspection apparatuses employ a plurality of detection methods described above in consideration of differences in defect shape, size, optical properties, and the like.

In surface inspection, it is necessary to detect and discriminate various defects, but the above-mentioned optical detection method alone has a limit in defect discrimination accuracy. Further, when foreign matter adheres to the surface of a semiconductor wafer, a liquid crystal substrate, a magnetic disk or the like, it is necessary to clarify the identity of the foreign matter in order to manage the production process. However, the shape, size, height, etc. measured by the above optical detection method cannot elucidate the identity of the foreign matter, and a detailed analysis using a separate X-ray analyzer may be required. It was. As for X-ray analysis, Patent Document 3 describes an X-ray tube that generates a plurality of types of X-rays. Patent Document 4 describes an X-ray analyzer that can measure a wide range of elements in a small size using the combination of the X-ray tube and the spectroscopic element described in Patent Document 3.
JP 2001-66263 A JP 2000-121317 A JP 2001-351551 A JP 2002-148225 A

  The present invention adds an X-ray analysis function to a surface inspection apparatus, and can perform X-ray analysis as necessary for defects such as foreign matter detected by optical inspection (for example, Patent Document 1 and Patent Document 2). It is something to do. The first problem to realize this is to make an X-ray analyzer capable of analyzing a wide range of elements small in size so that it can be incorporated into a surface inspection apparatus. In the X-ray analyzer described in Patent Document 4, since X-rays are irradiated onto the surface of the object to be inspected with a predetermined spread, a surface that analyzes a minute object such as a foreign object detected by optical inspection Not suitable for inspection. Therefore, the second problem is to enable analysis of minute objects so as to be suitable for surface inspection.

  The X-ray analyzer of the present invention has an X-ray tube that selectively generates a plurality of types of X-rays and a double-curved crystal surface that is provided for each type of X-ray generated by the X-ray tube. And switching the positions of a plurality of double-curved spectroscopic elements and a plurality of double-curved spectroscopic elements that make X-rays incident at a Bragg angle with a predetermined spread are Bragg-reflected and monochromatic by the crystal surface. X-rays generated by the X-ray tube are incident at a Bragg angle with a predetermined spread on the crystal surface of the double-curved spectroscopic element corresponding to the type of X-ray, and the X-rays are Bragg-reflected on the crystal surface of the double-curved spectroscopic element. Spectroscopic element switching means for irradiating the surface of the inspection object with the line.

  The X-ray analysis method of the present invention selectively generates a plurality of types of X-rays from one X-ray tube, and has a doubly curved crystal surface according to the type of X-rays generated. The X-rays incident at a Bragg angle with a predetermined spread are Bragg-reflected on the surface of the crystal to be monochromatized and switched, and the positions of a plurality of double-curved spectroscopic elements are switched, and the X-rays corresponding to the type are doubled. It is incident on the crystal surface of the curved spectroscopic element at a Bragg angle with a predetermined spread, and the surface of the object to be inspected is irradiated with X-rays reflected by the crystal surface of the double curved spectroscopic element.

  By switching the positions of a plurality of double-curved spectroscopic elements according to the type of X-rays generated by the X-ray tube, the X-rays generated from the X-ray tube are converted into crystals of the double-curved spectroscopic elements corresponding to the types. Incident to the surface with a predetermined spread at a Bragg angle. The crystal surface of the double-curved spectroscopic element is concavely curved with a first curvature, and X-rays incident at a Bragg angle with a predetermined spread are Bragg-reflected on the crystal surface of the double-curved spectroscopic element. Thus, it becomes a monochromatic X-ray. The crystal surface of the double curved spectroscopic element is curved in a concave shape with a second curvature in a direction orthogonal to the first curvature. Due to the first curvature and the second curvature, the X-rays monochromatic by Bragg reflection on the crystal surface of the double-curved spectroscopic element are focused in a spot shape on the surface of the object to be inspected.

  Furthermore, the X-ray analyzer of the present invention includes an angle adjustment plate to which the double curved spectroscopic element is attached, a support plate that supports the angle adjustment plate so as to be movable, and a plurality of adjustments that adjust the interval between the angle adjustment plate and the support plate. And an angle adjusting means for adjusting the angle of the double curved spectroscopic element.

  Furthermore, the X-ray analysis method of the present invention measures in advance the position on the surface of the object to be irradiated with X-rays for each type of generated X-ray, and each X-ray is covered based on the measurement result. The inspection object is moved so that the same position on the surface of the inspection object is irradiated.

  The surface inspection apparatus of the present invention detects the presence or absence of defects on the surface of the inspection object from the inspection result of the optical inspection apparatus that optically inspects the surface of the inspection object and the optical inspection apparatus, and detects the detected defects. The apparatus includes a processing device that detects a position and a feature on the surface of the inspection object and classifies the detected defect according to the feature, and any one of the X-ray analysis devices described above.

  According to the X-ray analyzer and the X-ray analysis method of the present invention, by using a double curved spectroscopic element, X-rays are monochromatized to eliminate X-rays other than the X-ray wavelength for elemental analysis, Wavelength X-rays can be irradiated. Therefore, it is possible to improve the detection sensitivity of fluorescent X-rays for specifying elements, improve the S / N ratio (reduce noise), and increase the intensity by focusing the X-rays in a spot shape. it can. An X-ray capable of analyzing a wide range of elements is provided by providing an X-ray tube that selectively generates a plurality of types of X-rays and a spectroscopic element switching unit that switches the positions of the plurality of double-curved spectroscopic elements. The analyzer can be configured in a small size. In addition, it is possible to analyze minute objects by focusing X-rays in a spot shape with a double curved spectroscopic element.

  Furthermore, according to the X-ray analyzer of the present invention, the angle of the double curved spectroscopic element can be adjusted with high accuracy by the angle adjusting means. Therefore, the X-rays can be efficiently monochromatic with the double curved spectroscopic element and can be focused at a desired position.

  Furthermore, according to the X-ray analysis method of the present invention, each X-ray can be irradiated to the same position on the surface of the object to be inspected even if the position where each X-ray is irradiated is somewhat different. Therefore, X-ray analysis using a plurality of X-rays can be performed with high accuracy.

  According to the surface inspection apparatus of the present invention, an optical inspection apparatus for optically inspecting the surface of an object to be inspected and an X-ray analysis apparatus are incorporated into one surface inspection apparatus, so that X-ray analysis of defects is performed in-line in real time. Can be done.

  FIG. 1 is a block diagram showing a schematic configuration of a surface inspection apparatus according to an embodiment of the present invention. FIG. 2 is an external view of the surface inspection apparatus according to the embodiment of the present invention. The present embodiment shows an example of a surface inspection apparatus that inspects defects on the surface of a semiconductor wafer. The surface inspection apparatus includes a processing apparatus 20, an optical inspection apparatus 30, an optical microscope 40, and an X-ray analysis apparatus 50.

  As shown in FIG. 2, an X stage 11 is provided in the longitudinal direction inside the processing apparatus 20, a Z stage 12 is provided on the X stage 11, and a θ stage is provided on the Z stage 12. 13 is provided. A chuck 14 is mounted on the θ stage 13. The chuck 14 moves on the upper surface of the processing apparatus 20 in the X direction by the action of the X stage 11 and moves up and down in the Z direction by the action of the Z stage 12. Further, it is rotated by the action of the θ stage 13.

  Above the processing device 20, a centering position, an optical inspection device 30, an X-ray analysis device 50, and an optical microscope 40 are provided in order in the X direction. The semiconductor wafer 1 that is the object to be inspected is first mounted on the chuck 14 at the centering position after pre-alignment such as alignment of the orientation flat or V-notch is performed. At the centering position, the center of the semiconductor wafer 1 is aligned by the action of each stage.

  Subsequently, the semiconductor wafer 1 is carried below the optical inspection device 30 by the action of the X stage 11. Below the optical inspection apparatus 30, the θ stage 13 rotates the semiconductor wafer 1, and the X stage 13 moves the semiconductor wafer 1 in the X direction. By these rotation and movement, the inspection light spot irradiated from the optical inspection apparatus 30 scans the surface of the semiconductor wafer 1 in a spiral shape. The optical inspection device 30 is the same as a conventional surface inspection device, and includes, for example, an optical system of a scattered light detection method and a reflected light detection method described in Patent Document 1, or interference described in Patent Document 2. A phase detection type optical system is provided, or both of them are provided.

  As shown in FIG. 1, the processing device 20 includes drive circuits 15, 16, 17, MPU 21, memory 22, interfaces 23a, 23e, 23f, input device 24, display device 25, output device 26, position control circuit 27, PM. A control circuit 28 and a bus 29 are included. The MPU 21 controls the memory 22, the interfaces 23a, 23e, and 23f, the input device 24, the display device 25, the output device 26, the position control circuit 27, and the PM control circuit 28 via the bus 29.

  Below, the outline | summary of operation | movement of the processing apparatus 20 is demonstrated. First, the MPU 21 executes a defect detection program 22 a stored in the memory 22. The position control circuit 27 drives the X stage 11 and the θ stage 13 via the drive circuits 15 and 17 under the control of the MPU 21 to scan the surface of the semiconductor wafer 1 with the inspection light spot from the optical inspection apparatus 30. . The optical inspection device 30 optically inspects the surface of the semiconductor wafer 1 and outputs the inspection result to the interface 23a.

  The MPU 21 detects the presence / absence of defects on the surface of the semiconductor wafer 1 from the inspection result of the optical inspection apparatus 30 input via the interface 23a, and detects the position and features of the detected defects. The position of the defect is, for example, an X coordinate, and an r coordinate and a θ coordinate based on the center of the semiconductor wafer 1. The feature of the defect is, for example, the unevenness of the defect, the size of the defect, the height or depth of the defect, and the like.

  Next, the MPU 21 classifies the detected defect according to the feature by comparing the feature data of the detected defect with the data of the defect feature parameter table 22 b stored in the memory 22. The classification of defects is, for example, the types of defects such as convex portions (bumps), dust (particles), concave portions (pits), and scratches (scratches), and differences in their sizes. Under the control of the MPU 21, the memory 22 stores defect feature data and defect classification result data in association with defect position data.

  When the inspection by the optical inspection device 30 and the processing by the processing device 20 are completed for the entire surface of the semiconductor wafer 1, the MPU 21 is stored in the memory 22 automatically or in response to an instruction using the operator input device 24. The defect map display program 22c is executed. The MPU 21 creates a defect map from the defect position data and defect classification result data stored in the memory 22 and displays the defect map on the display device 25. The defect map is obtained by symbolizing detected defects according to the classification result, and representing the position of the defect on the semiconductor wafer by the position of the symbol on the map.

  The operator looks at the defect map displayed on the display device 25 and determines whether or not detailed analysis is necessary for each individual defect. In the present embodiment, shape analysis, observation with an optical microscope, and X-ray analysis can be performed as detailed analysis of defects. When the operator determines that these analyzes are necessary, the operator designates the target defect and the type of analysis using the input device 24.

  When shape analysis is designated, the MPU 21 executes a defect shape analysis program 22 d stored in the memory 22. The position control circuit 27 drives the X stage 11 and the θ stage 13 via the drive circuits 15 and 17 on the basis of the designated defect position data stored in the memory 22 under the control of the MPU 21, and performs optical inspection. The semiconductor wafer 1 is moved and rotated so that the inspection light spot from the apparatus 30 is irradiated to the designated defect. As a result, the optical inspection apparatus 30 performs a detailed reinspection of the designated defect on the surface of the semiconductor wafer 1, and outputs the reinspection result to the interface 23a. The MPU 21 performs shape analysis of the designated defect from the reinspection result by the optical inspection device 30 input via the interface 23a, and displays the analysis result on the display device 25. The analysis result may be displayed as long as the operator can visually determine the shape of the defect, such as a three-dimensional image, a contour map, and a cross-sectional shape.

  When the observation with the optical microscope is designated, the MPU 21 executes the defect observation program 22 e stored in the memory 22. The position control circuit 27 drives the X stage 11 via the drive circuit 15 under the control of the MPU 21 to move the semiconductor wafer 1 below the optical microscope 40. Next, the position control circuit 27 drives the X stage 11 and the θ stage 13 via the drive circuits 15 and 17 based on the designated defect position data stored in the memory 22 under the control of the MPU 21. The semiconductor wafer 1 is moved and rotated so that the optical microscope 40 detects an image of the designated defect. Then, the position control circuit 27 drives the Z stage 12 via the drive circuit 16 based on the designated defect height or depth data stored in the memory 22 under the control of the MPU 21, and the optical microscope. Autofocus is performed so that the focus of 40 matches the surface of the designated defect. Thereby, the optical microscope 40 detects an image of the designated defect on the surface of the semiconductor wafer 1 and outputs it to the interface 23e. The MPU 21 displays on the display device 25 an image of the defect by the optical microscope 40 input via the interface 23e.

  When X-ray analysis is designated, the MPU 21 executes an X-ray analysis program 22 f stored in the memory 22. The position control circuit 27 drives the X stage 11 through the drive circuit 15 under the control of the MPU 21 to move the semiconductor wafer 1 downward of the X-ray analyzer 50. Next, the position control circuit 27 drives the X stage 11 and the θ stage 13 via the drive circuits 15 and 17 based on the designated defect position data stored in the memory 22 under the control of the MPU 21. The semiconductor wafer 1 is moved and rotated so that X-rays from the X-ray analyzer 50 are irradiated to the designated defect. As a result, the X-ray analysis apparatus 50 performs X-ray analysis of the designated defect on the surface of the semiconductor wafer 1, and outputs the analysis result to the interface 23f. The X-ray analyzer 50 will be described later.

  The MPU 21 is designated by comparing and collating the data of the X-ray analysis result by the X-ray analyzer 50 inputted through the interface 23f with the spectrum data of the substance registered in the defective substance registration library 22g of the memory 22. Determine the defective material. The defective substance registration library 22g pre-registers spectrum data of substances that may be detected by X-ray analysis in consideration of foreign materials that may be mixed in the material constituting the inspection object and the manufacturing process. It is what. The determination result of the defect substance is, for example, an organic or inorganic type, a metal type, a magnetic type, a semiconductor type, an amorphous carbon type, or a water stain. Under the control of the MPU 21, the memory 22 stores the defect X-ray analysis result data and the defect substance determination result data in association with the defect position data.

  Next, the MPU 21 reclassifies the defect based on the data of the determination result of the defective substance. Under the control of the MPU 21, the memory 22 stores the defect reclassification result data in association with the defect position data. Finally, the MPU 21 stores defect position data, defect feature data, defect X-ray analysis result data, defect substance determination result data, and defect reclassification result data stored in the memory 22. Based on the above, the inspection result is displayed on the display device 25 or output to the output device 26.

  The operation of the processing apparatus 20 described above is that the operator of the surface inspection apparatus designates a defect for performing X-ray analysis, but the defect for performing X-ray analysis can also be automatically selected by the surface inspection apparatus. . In this case, a program for selecting a defect to be subjected to X-ray analysis is added to the memory 22. The MPU 21 executes the added program and selects a defect to be subjected to X-ray analysis. Then, the X-ray analysis is performed on the selected defect as in the case where the operator designates it.

  The program for selecting a defect to be subjected to X-ray analysis includes sampling conditions for defects for which X-ray analysis is performed, priority for performing X-ray analysis, and the like. As an example, the surface of the semiconductor wafer 1 is divided into regions of a predetermined area, and regions having a defect density (the number of defects detected for each divided region) are equal to or higher than a predetermined value in order of increasing defect density. It is assumed that the maximum or predetermined size of the defect is sampled. The sampling conditions of defects for performing X-ray analysis and the priority order for performing X-ray analysis are not limited to this. For defects of a predetermined size or larger, the order of defect sizes, or defects classified into specific types are determined. The order can be determined as appropriate, such as the order of classification.

  According to the embodiment described above, X-ray analysis of defects can be performed in-line in real time by incorporating the optical inspection apparatus and the X-ray analysis apparatus into one surface inspection apparatus.

  Next, the X-ray analyzer 50 will be described. The X-ray analyzer of the present embodiment performs X-ray analysis using three different types of X-rays. FIG. 3 shows the first X-ray of the X-ray analyzer according to the embodiment of the present invention. 4 is a partial cross-sectional side view when using the second X-ray, FIG. 4 is a partial cross-sectional side view when using the second X-ray, and FIG. 5 is a partial cross-sectional side view when using the third X-ray. The X-ray analysis apparatus 50 includes an X-ray generation unit 60, an X-ray focusing unit 70, a PM (Pulse Motor) driving circuit 71, an X-ray detector 90, and a DSP (Digital Signal Processor) 91.

  The X-ray generator 60 includes an X-ray tube 61 in a sealed container, and an insulating oil is sealed in the sealed container to cool the X-ray tube 61. A window 62 made of beryllium (Be) is provided at the bottom of the sealed container to allow X-rays generated by the X-ray tube 61 to pass therethrough. The X-ray tube 61 has the same configuration as the X-ray tube described in Patent Document 3, and selectively generates three different types of X-rays using three types of targets. As an example, chromium (Cr), tungsten (W), and silver (Ag) are used for the target.

  As the X-ray tube 61, a sealed type whose inside is previously in a vacuum state may be used, or an open type whose inside is not in a vacuum state from the beginning may be used. In the case of using an open type, the inside of the X-ray tube 61 is brought into a necessary high vacuum state using a molecular pump (not shown) and then switched to an ion pump to maintain the high vacuum state. By using the molecular pump, the inside of the X-ray tube 61 can be brought into a high vacuum state in a short time, and after reaching the high vacuum state, vibration and noise are compared with the molecular pump by using the ion pump. Etc. are kept low.

  The X-ray focusing unit 70 includes three double-curved spectroscopic elements 80a, 80b, and 80c corresponding to three types of X-rays generated from the X-ray tube 61 in the sealed container, and positions of these double-curved spectroscopic elements. And a spectral element switching mechanism for switching between. A window 78 made of beryllium (Be) is provided at the bottom of the sealed container to irradiate the surface of the semiconductor wafer 1 with X-rays. X-rays generated from the X-ray tube 61 and passing through the window 62 are Bragg-reflected on the crystal surface of any of the double curved spectroscopic elements 80 a, 80 b, 80 c, and irradiated to the surface of the semiconductor wafer 1 through the window 78. Is done.

  FIG. 6 is a diagram illustrating the operation of the double curved spectroscopic element. As an example, the surfaces of the double curved spectroscopic elements 80a, 80b, and 80c are made of silicon (Si) crystal having a crystal orientation (1, 1, 1). In the case of the double curved spectroscopic element 80a shown in FIG. 6, the crystal surface of the double curved spectroscopic element 80a is curved in a concave shape with a predetermined curvature R1 in the vertical direction. The first X-ray 2a incident at a Bragg angle with a predetermined spread from the X-ray generator 60 is Bragg-reflected on the crystal surface of the double curved spectroscopic element 80a to become a monochromatic X-ray 3a. The crystal surface of the double curved spectroscopic element 80a is curved in a concave shape with a predetermined curvature R2 in the lateral direction. Due to the curvature R1 and the curvature R2, the X-rays 3a that are monochromatic by Bragg reflection on the crystal surface of the double curved spectroscopic element 80a are focused in a spot shape on the surface of the semiconductor wafer 1. The double curved spectroscopic element 80b is the same for the second X-ray, and the double curved spectroscopic element 80c is the same for the third X-ray.

  FIG. 7A is a side view of the spectroscopic element switching mechanism, and FIG. 7B is a top view thereof. The spectroscopic element switching mechanism includes a base 72, a pulse motor 73, a coupling 74, a ball screw 75, a guide 76, and a moving table 77. The base 72 supports the ball screw 75 in a rotatable manner. A pulse motor 73 is attached to one end of the base 72, and the rotation of the pulse motor 73 is transmitted to the ball screw 75 via the coupling 74. Double curved spectroscopic elements 80 a, 80 b, and 80 c are attached to the moving table 77, and the moving table 77 moves along the guide 76 by the rotation of the ball screw 75.

  Note that the base 72 is attached to the inner wall of the sealed container of the X-ray focusing unit 70 obliquely by a predetermined angle α with respect to the horizontal. Thereby, the X-ray generated from the X-ray generator 60 is shifted from the position directly below the X-ray generator 60 where the X-rays that are Bragg-reflected on the crystal surfaces of the double curved spectroscopic elements 80a, 80b, and 80c are irradiated. Direct irradiation onto the surface of the semiconductor wafer 1 can be prevented. In order to shift the position irradiated with the X-rays that are Bragg-reflected on the crystal surfaces of the double curved spectroscopic elements 80a, 80b, and 80c from directly below the X-ray generator 60, instead of attaching the base 72 diagonally, The curved spectroscopic elements 80 a, 80 b, and 80 c may be attached to the moving table 77 obliquely with a predetermined angle with respect to the vertical.

  In this embodiment, when X-ray analysis is designated by an operator or X-ray analysis is automatically selected by a program, X-ray analysis by one or more of three types of X-rays is designated or selected. . When the X-ray analysis by the first X-ray is designated or selected, the PM control circuit 28 drives the pulse motor 73 via the PM drive circuit 71 under the control of the MPU 21 as shown in FIG. The moving base 77 is moved so that the heavy curved spectroscopic element 80a comes to a predetermined position. As a result, the first X-ray 2a generated from the X-ray tube 61 and passing through the window 62 enters the crystal surface of the double curved spectroscopic element 80a with a predetermined spread at a Bragg angle. The X-rays 3a that are monochromatic by Bragg reflection on the crystal surface of the double curved spectroscopic element 80a are irradiated to the surface of the semiconductor wafer 1 through the window 78 in a spot shape.

  When the X-ray analysis by the second X-ray is designated or selected, the PM control circuit 28 drives the pulse motor 73 via the PM drive circuit 71 under the control of the MPU 21 as shown in FIG. The moving base 77 is moved so that the heavy curved spectroscopic element 80b comes to a predetermined position. Accordingly, the second X-ray 2b generated from the X-ray tube 61 and passing through the window 62 is incident on the crystal surface of the double curved spectroscopic element 80b with a predetermined spread at a Bragg angle. The X-rays 3b that are monochromatic by Bragg reflection on the crystal surface of the double curved spectroscopic element 80b are irradiated to the surface of the semiconductor wafer 1 through the window 78 in a spot shape.

  When the X-ray analysis by the third X-ray is designated or selected, the PM control circuit 28 drives the pulse motor 73 via the PM drive circuit 71 under the control of the MPU 21 as shown in FIG. The moving base 77 is moved so that the heavy curved spectroscopic element 80c comes to a predetermined position. Thus, the third X-ray 2c generated from the X-ray tube 61 and passing through the window 62 is incident on the crystal surface of the double curved spectroscopic element 80c with a predetermined spread at a Bragg angle. X-rays 3 c that are monochromatic by Bragg reflection on the crystal surface of the double curved spectroscopic element 80 c are irradiated to the surface of the semiconductor wafer 1 through the window 78 in a spot shape.

  When X-rays are irradiated, the atoms on the surface of the semiconductor wafer 1 are excited and fluorescent X-rays are generated. The X-ray detector 90 is made of, for example, a semiconductor element called SSD (Solid-State Detector), and detects fluorescent X-rays generated from the surface of the semiconductor wafer 1 and passing through the window 78. The detection signal of the X-ray detector 90 is A / D converted by the DSP 91 and then output to the interface 23f.

  An illumination 81 using an optical fiber and a condensing lens and a camera 84 including a magnifying optical system are attached to the side surface of the sealed container of the X-ray focusing unit 70, and mirrors 82 and 83 are provided above the window 78. It has been. The illumination light emitted from the illumination 81 is reflected by the mirror 82 and applied to the periphery of the position where the surface of the semiconductor wafer 1 is irradiated with X-rays, and the reflected light from the surface of the semiconductor wafer 1 is reflected by the mirror 83. Then, an image is formed on the light receiving surface of the camera 84. An image of the surface of the semiconductor wafer 1 detected by the light receiving surface of the camera 84 is displayed on a monitor (not shown). Thereby, the operator can observe the defect which is performing X-ray analysis. Further, the position of the semiconductor wafer 1 can be finely adjusted while viewing the monitor image.

  If the inside of the sealed container of the X-ray focusing unit 70 is set to a low vacuum of about several Torr, the influence of air inside the X-ray passing through the X-ray focusing unit 70 is reduced, and the accuracy of the X-ray analysis is reduced. Will improve. Further, when the sealed container is made of a material made of a light element such as duralumin, the fluorescent X-ray generated from the sealed container itself is reduced, and the accuracy of X-ray analysis is improved.

  According to the embodiment described above, by using the double curved spectroscopic element, X-rays are monochromatized, X-rays other than the X-ray wavelength for elemental analysis are eliminated, and single wavelength X-rays for analysis are irradiated. be able to. Therefore, it is possible to improve the detection sensitivity of fluorescent X-rays for specifying elements, improve the S / N ratio (reduce noise), and increase the intensity by focusing the X-rays in a spot shape. it can. An X-ray capable of analyzing a wide range of elements by providing an X-ray tube that selectively generates a plurality of types of X-rays and a spectroscopic element switching mechanism that switches the positions of the plurality of double-curved spectroscopic elements. The analyzer can be configured in a small size. In addition, it is possible to analyze minute objects by focusing X-rays in a spot shape with a double curved spectroscopic element.

  In the X-ray analyzer of the type that switches a plurality of double curved spectroscopic elements as described above, in order to efficiently make each X-ray monochromatic with each double curved spectroscopic element and focus it on a desired position, It is necessary to adjust the angle of each double curved spectroscopic element with high accuracy. Hereinafter, the angle adjustment mechanism of the double curved spectroscopic element will be described. 8A is a side view of an angle adjusting mechanism according to an embodiment of the present invention, FIG. 8B is a rear view thereof, FIG. 8C is a top view thereof, and FIG. 8D is FIG. It is a figure which shows the attachment position of the tension spring in a). The angle adjustment mechanism includes an angle adjustment plate 85, a support plate 86, tension springs 87a, 87b, 87c, and adjustment screws 88a, 88b, 88c.

  The double curved spectroscopic element 80 a is attached to the angle adjustment plate 85. The support plate 86 is attached to the moving table 77, and supports the angle adjustment plate 85 movably by three tension springs 87a, 87b, 87c. Three adjustment screws 88a, 88b, 88c are attached to the support plate 86 in order to adjust the distance between the angle adjustment plate 85 and the support plate 86. The tips of the adjustment screws 88a, 88b, 88c are angle adjustment plates. 85 is in contact. By tightening or loosening the adjusting screws 88a, 88b, 88c, the angle between the angle adjusting plate 85 and the support plate 86 can be adjusted at three locations, and the angle of the double curved spectroscopic element 80a can be adjusted with high accuracy. . Therefore, the first X-ray can be efficiently monochromatic by the double curved spectroscopic element 80a and can be focused at a desired position. The same applies to the double curved spectroscopic elements 80b and 80c.

  As shown in FIG. 8D, the tension springs 87a and 87c and the tension spring 87b have different attachment positions in the horizontal direction of the drawing. As a result, even if the tension of the tension springs 87a, 87b, 87c fluctuates, they can be canceled. In addition, the number and arrangement | positioning of a tension spring and an adjustment screw are not restricted to the example shown in FIG.

  9A is a side view of an angle adjusting mechanism according to another embodiment of the present invention, FIG. 9B is a rear view thereof, FIG. 9C is a top view thereof, and FIG. 9D is FIG. It is a figure which shows the attachment position of the tension spring in (a). As shown in FIG. 9, a steel ball 89 may be provided at substantially the center between the angle adjusting plate 85 and the support plate 86, and the angle adjusting plate 85 may be moved with the steel ball 89 as a fulcrum. .

  Adjustment of the angle of each double-curved spectroscopic element using the angle adjusting mechanism is performed when the X-ray analyzer is first installed, when the X-ray tube is replaced due to the life of the X-ray source, or when the double-curved spectroscopic element is used. This is done when the is replaced. Even if the angle of each double-curved spectroscopic element is adjusted with high accuracy using the angle adjusting mechanism, each X-ray is irradiated due to a shift in the movement position of each double-curved spectroscopic element by the spectroscopic element switching mechanism. The positions on the surface of the semiconductor wafer 1 are not necessarily completely coincident. Therefore, in the present embodiment, the position where each X-ray is irradiated is measured in advance, and the semiconductor wafer 1 is positioned for each X-ray based on the result.

For example, the X (r) coordinate, the θ coordinate, and the Z coordinate of the position where each X-ray is irradiated onto the surface of the semiconductor wafer 1 are measured using the image of the camera 84 described above. Then, the measurement result is stored in the memory 22 of FIG. The position control circuit 27 is controlled by the MPU 21 based on the specified defect position data and defect height or depth data stored in the memory 22 and the measurement result data. The X stage 11, the Z stage 12 and the θ stage 13 are driven via 16, 17, and the semiconductor wafer 1 is moved up and down and up and down so that the position of the designated defect coincides with the position where each X-ray is irradiated. Rotate. Thereby, even if the position where each X-ray is irradiated is somewhat different, each X-ray can be irradiated to the designated defect. Therefore, X-ray analysis using a plurality of X-rays can be performed with high accuracy.
In the embodiment described above, three types of X-rays are used. However, the X-ray analyzer of the present invention is not limited to this, and uses a plurality of types of X-rays. The present invention is not limited to semiconductor wafers and can be applied to inspection of defects on the surface of various objects such as liquid crystal substrates and magnetic disks.

It is a block diagram which shows schematic structure of the surface inspection apparatus by one embodiment of this invention. 1 is an external view of a surface inspection apparatus according to an embodiment of the present invention. It is a partial cross section side view when the X-ray analyzer by one embodiment of this invention uses a 1st X-ray. It is a partial cross section side view when the X-ray analyzer by one embodiment of this invention uses a 2nd X-ray. It is a partial cross section side view when the X-ray analyzer by one embodiment of this invention uses a 3rd X-ray. It is a figure which shows operation | movement of a double curve spectroscopic element. FIG. 7A is a side view of the spectroscopic element switching mechanism, and FIG. 7B is a top view thereof. 8A is a side view of an angle adjusting mechanism according to an embodiment of the present invention, FIG. 8B is a rear view thereof, FIG. 8C is a top view thereof, and FIG. 8D is FIG. It is a figure which shows the attachment position of the tension spring in a). 9A is a side view of an angle adjusting mechanism according to another embodiment of the present invention, FIG. 9B is a rear view thereof, FIG. 9C is a top view thereof, and FIG. 9D is FIG. It is a figure which shows the attachment position of the tension spring in (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor wafer 11 X stage 12 Z stage 13 (theta) stage 20 Processing apparatus 30 Optical inspection apparatus 40 Optical microscope 50 X-ray analyzer 60 X-ray generation part 70 X-ray focusing part 80a, 80b, 80c Double curve spectroscopic element 90 X-ray Detector

Claims (5)

An X-ray tube that selectively generates a plurality of types of X-rays;
It is provided for each type of X-ray generated by the X-ray tube, has a double-curved crystal surface, and is monochromatic by Bragg-reflecting X-rays incident at a Bragg angle with a predetermined spread. A plurality of double curved spectroscopic elements for focusing and focusing;
By switching the positions of the plurality of double-curved spectroscopic elements, the X-rays generated by the X-ray tube are incident at a Bragg angle with a predetermined spread on the crystal surface of the double-curved spectroscopic element corresponding to the type. An X-ray analysis apparatus comprising: a spectroscopic element switching unit that irradiates the surface of an object to be inspected with X-rays that are Bragg-reflected on a crystal surface of a double curved spectroscopic element.   An angle adjusting plate to which the double curved spectroscopic element is attached; a support plate for movably supporting the angle adjusting plate; and a plurality of adjusting screws for adjusting the interval between the angle adjusting plate and the support plate. 2. The X-ray analyzer according to claim 1, further comprising angle adjusting means for adjusting an angle of the double curved spectroscopic element. A plurality of types of X-rays are selectively generated from one X-ray tube,
Depending on the type of X-rays to be generated, a plurality of crystal surfaces having a double curved crystal surface, X-rays having a predetermined spread and incident at a Bragg angle are Bragg-reflected on the crystal surface to be monochromatic and focused. The position of the double-curved spectroscopic element is switched, and X-rays are incident on the crystal surface of the double-curved spectroscopic element corresponding to the type with a predetermined spread at a Bragg angle, and Bragg is made on the crystal surface of the double-curved spectroscopic element. An X-ray analysis method comprising irradiating the surface of an inspection object with reflected X-rays. For each type of X-ray generated, the position on the surface of the inspection object irradiated with the X-ray is measured in advance,
The X-ray analysis method according to claim 3, wherein the inspection object is moved so that each X-ray is irradiated to the same position on the surface of the inspection object based on the measurement result. An optical inspection device for optically inspecting the surface of the object to be inspected;
From the inspection result of the optical inspection device, the presence or absence of a defect on the surface of the inspection object is detected, the position and feature of the detected defect on the surface of the inspection object are detected, and the detected defect according to the feature. A processing device for classification,
A surface inspection apparatus comprising the X-ray analysis apparatus according to claim 1.

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