Semiconductor inspecting device, semiconductor inspecting system, and semiconductor inspecting method

Abstract

Provided are: a semiconductor inspecting device capable of inspecting, for every region, a microstructure of the inside of a semiconductor by obtaining an enlarged image with sufficient strength, with a size accommodatable in a laboratory; and a corresponding semiconductor inspecting system and semiconductor inspecting method. This semiconductor inspecting device uses an enlarged X-ray image. The semiconductor inspecting device comprises: an X-ray source 120 with fine focus and high output power; an X-ray irradiation unit including a condenser mirror 130 that condenses emitted X-rays and irradiates a semiconductor sample with same; a sample holding unit holding the sample; a reflective mirror-type X-ray lens unit 150 forming an image of X-rays passing through the sample; and an imaging unit 190 acquiring the formed X-ray image. Each of mirrors constituting the condenser mirror 130 and the reflective mirror-type X-ray lens unit 150 has a reflection plane in which a multi-layered film having high reflectance against an X-ray having a designated wavelength is formed.

Description

Semiconductor inspection device, semiconductor inspection system, and semiconductor inspection method

[0001] The present invention relates to a semiconductor inspection device, a semiconductor inspection system, and a semiconductor inspection method that use magnified X-ray images.

[0002] In recent years, semiconductor circuits have become increasingly highly integrated, resulting in the development of semiconductors with fine structures parallel to the surface and extending deeper in the thickness direction. The surface structures and internal structures processed by etching of such semiconductors have become difficult to inspect using conventional optical inspection methods or CD-SEM (Critical Dimension Scanning Electron Microscope). Therefore, when attempting to inspect the shape and dimensions of long holes in the thickness direction, destructive inspection methods such as cross-sectional SEM and TEM have become necessary. However, nondestructive inspection methods are strongly required for managing the semiconductor manufacturing process. One such method is transmission SAXS, which analyzes the average structure of an area approximately several hundred microns in diameter from the pattern of small-angle scattered X-rays. However, while such methods can inspect averaged structures, they cannot inspect defects in individual structures as can be done with a microscope.

[0003] On the other hand, in conventional imaging X-ray microscopes, Fresnel zone plate lenses (FZP) are often used in the imaging system (see, for example, Patent Document 1). However, when FZP is applied to high-energy X-rays, it is difficult to increase the aspect ratio, and the diffraction efficiency drops significantly. For example, when X-rays of 15 keV or more are imaged with an FZP, the efficiency is several percent or less. In addition, the numerical aperture (NA) in this case is also 1×10 －３ Therefore, it has been difficult to realize a high-resolution X-ray microscope using high-energy X-rays in a laboratory.

[0004] In response to this, an X-ray microscope that uses a Kirkpatrick-Baez mirror (KB mirror) has been developed as a size that can be carried indoors (see, for example, Patent Document 2). The X-ray microscope described in Patent Document 2 configures an imaging system using a KB mirror with a reflective concave surface and a KB mirror with a reflective convex surface. As a result, the back focal length of the optical system is shortened while maintaining the magnification.

[0005] U.S. Patent No. 7,394,890

[0006] In the field of semiconductor manufacturing, semiconductor devices are currently being developed that have structures of several tens of nanometers parallel to the surface and extending over several micrometers in the depth direction. However, conventional inspection equipment cannot nondestructively inspect the complex structures inside deep hole structures.

[0007] The X-ray microscope described in Patent Document 2 utilizes total internal reflection of X-rays, so the angle of incidence must be limited to a critical angle or less, and to realize a lens with a large numerical aperture, the size in the direction of the X-ray beam must be long. In particular, in the application fields of X-ray microscopes, there is a demand for microscopes that are small enough to be installed in laboratories and that can form images with high efficiency even with high-energy X-rays.

[0008] The present invention has been made in consideration of the above circumstances, and aims to provide a semiconductor inspection device, a semiconductor inspection system, and a semiconductor inspection method that are small enough to be stored in a laboratory and can obtain magnified images with sufficient strength to inspect the microstructure inside a semiconductor locally.

[0009] (1) In order to achieve the above object, the semiconductor inspection device of the present invention is a semiconductor inspection device that uses a magnified X-ray image, and comprises an X-ray irradiation unit consisting of a fine-focus, high-output X-ray source, a condenser mirror that focuses and irradiates the emitted X-rays toward a semiconductor sample, a sample holder that holds the sample, a reflective mirror-type X-ray lens unit that forms an image of the X-rays that have passed through the sample, and an imaging unit that acquires the formed X-ray image, and is characterized in that each of the mirrors that constitute the condenser mirror and the reflective mirror-type X-ray lens unit has a reflective surface on which a multilayer film that has high reflectivity for X-rays of a specific wavelength is formed.

[0010] (2) In the semiconductor inspection device described in (1) above, the sample comprises a substrate on which a semiconductor circuit is formed, and a semiconductor device layer provided on the substrate.

[0011] (3) In the semiconductor inspection device described in (1) or (2) above, the sample is a plate-like body having a thickness of 500 μm or more.

[0012] (4) In the semiconductor inspection device described in any one of (1) to (3) above, the distance on the optical axis from the sample to the light receiving surface of the imaging unit is 3 m or less.

[0013] (5) In the semiconductor inspection device described in any one of (1) to (4) above, the aperture angle of the reflection mirror type X-ray lens unit is 5 mrad or more.

[0014] (6) Furthermore, the semiconductor inspection device described in any one of (1) to (5) above is characterized by further comprising a position adjustment mechanism that can adjust the relative position of the sample with respect to each part under automatic or operator-based control.

[0015] (7) Furthermore, the semiconductor inspection system of the present invention comprises a semiconductor inspection device according to any one of (1) to (6) above, and a control device connected to the semiconductor inspection device, wherein the control device adjusts the relative position of the sample with respect to each part of the semiconductor inspection device automatically or based on instructions from a user.

[0016] (8) Furthermore, a semiconductor inspection system of the present invention comprises a semiconductor inspection device according to any one of (1) to (6) above, and an analysis device connected to the semiconductor inspection device, wherein the analysis device quantitatively evaluates the surface density of material at each position based on an absorption coefficient in an X-ray image acquired by the semiconductor inspection device.

[0017] (9) Furthermore, the semiconductor inspection system of the present invention comprises the semiconductor inspection device described in (1) or (2) above, and an analysis device connected to the semiconductor inspection device, and is characterized in that the analysis device evaluates the structure related to holes formed in the sample based on the absorption coefficient in the X-ray image acquired by the semiconductor inspection device.

[0018] (10) In the semiconductor inspection system described in (9) above, the X-ray image is measured with the sample tilted.

[0019] (11) Furthermore, a semiconductor inspection method of the present invention is a non-destructive semiconductor inspection method using the semiconductor inspection device described in any one of (1) to (6) above, characterized by including the steps of placing the sample on the sample holder, irradiating the sample with X-rays of 15 keV or more, and evaluating the presence or absence of defects in the sample based on the formed X-ray image.

[0020] 1 is a schematic diagram showing an imaging X-ray microscope. (a) and (b) are plan and front views, respectively, showing the optical system of an imaging X-ray microscope. (b) are schematic diagrams showing the collection angle and aperture angle. (c) are cross-sectional views showing a multilayer film. (a) and (b) are plan views showing a vertical reflection mirror set and a horizontal reflection mirror set, respectively. (c) are graphs showing the design and measured values ​​of the periodic length of the multilayer film relative to the position of the first vertical reflection imaging mirror. (d) are graphs showing the design and measured values ​​of the periodic length of the multilayer film relative to the position of the second vertical reflection imaging mirror. (e) are graphs showing the design and measured values ​​of the periodic length of the multilayer film relative to the position of the first horizontal reflection imaging mirror. (f) are graphs showing the design and measured values ​​of the periodic length of the multilayer film relative to the position of the second horizontal reflection imaging mirror. (g) are graphs showing the magnitude of the error in the surface shape relative to the position of the second horizontal reflection imaging mirror. (a) and (b) are X-ray images of a 50 nm L&S chart and a 50 nm star chart, respectively. (a) and (b) are X-ray images of a 100 nm hole chart and the intensity distribution of a portion thereof, respectively. 1 is a schematic diagram showing an example of application of an imaging X-ray microscope of the present invention to a semiconductor inspection device.

[0021] Next, an embodiment of the present invention will be described with reference to the drawings. To facilitate understanding of the description, the same reference numerals are used to designate the same components in the drawings, and duplicated descriptions will be omitted.

[0022] The imaging X-ray microscope described below can be used in the semiconductor inspection device of the present invention. First, the imaging X-ray microscope will be described, and its application to semiconductor inspection will be described later.

[0023] [Imaging X-ray Microscope] FIG. 1 is a schematic diagram of an imaging X-ray microscope 100. The imaging X-ray microscope 100 is composed of a high-intensity X-ray source 120, a condenser mirror 130, a sample holder 140, a reflective mirror-type X-ray lens unit 150, and a high-resolution X-ray detector 190 (image capture unit). The X-ray reflecting mirrors used in the condenser mirror 130 and the reflective mirror-type X-ray lens unit 150 are coated with multilayer films. The reflective surfaces formed with multilayer films have high reflectivity for X-rays of specific wavelengths, and by maintaining a high X-ray incidence angle, the numerical aperture can be increased, making it possible to acquire high-resolution X-ray magnified images in a short time. The resolution δ of the imaging X-ray microscope 100 can be expressed as δ = kλ / NA, where k is the constant, λ is the wavelength of the irradiated X-rays, and NA is the numerical aperture.

[0024] Such an imaging X-ray microscope 100 is highly useful, for example, in inspecting miniaturized and highly dense semiconductor devices in which structures on the scale of several tens of nanometers are formed to a thickness of several micrometers. If product wafers could be nondestructively observed or inspected using the imaging X-ray microscope 100, productivity in device manufacturing could be greatly improved. Furthermore, the imaging X-ray microscope 100 enables observation of areas 50 nm to 1 μm in size, for example, in the field of life science research. Specific examples include the internal structures of organelles, cells, tissues, organs, and organ systems, the morphology of model cells and disease model cells, and the morphology of mutation sites in genetically modified animals. The X-ray microscope enables the observation of CT images 50 nm to 1 μm in size, allowing three-dimensional observation of thick cells without the need for thinning.

[0025] The X-ray irradiation unit 110 includes an X-ray source 120, a condenser mirror 130, and an aperture 135, and irradiates a sample with finely focused, high-power X-rays. The X-ray source 120 is preferably a rotating anode-type finely focused, high-power X-ray source. The irradiated X-rays preferably have an energy of 4 keV or greater. X-ray energy and wavelength are inversely proportional, with higher energy resulting in shorter wavelengths. Therefore, using such short-wavelength X-rays can increase the theoretical limit of resolution δ of the imaging X-ray microscope 100. Examples of targets for the X-ray source that determine the X-ray wavelength include Cr, Cu, Mo, and Ag.

[0026] The X-ray source 120 preferably generates X-rays with an output of 500 W or more, and even better, 1 kW or more. This increases the intensity of the irradiated X-rays. The condenser mirror 130 is optimized in design to focus the generated X-rays onto a small irradiation area at a collection angle optimal for the numerical aperture of the X-ray lens. A multilayer film with high reflectivity for X-rays of the required wavelength is formed on the mirror surface. The configuration of the multilayer film will be described in detail later. In this specification, "having high reflectivity" is synonymous with "when the intensity of the incident characteristic X-rays is 100%, the intensity of the characteristic X-rays reflected per reflection by the mirror is 70% or more."

[0027] The aperture 135 can control the opening in a first direction and a second direction perpendicular to the X-ray irradiation direction, and adjusts the size of the X-rays in each direction toward the sample S. In this embodiment, the first direction represents the vertical direction and the second direction represents the horizontal direction, but this is not necessarily limited to this.

[0028] The sample holder 140 has a rotation stage capable of highly accurate rotation control, and holds the sample S. By photographing the sample S while rotating it on the rotation stage, it is also possible to reconstruct a stereoscopic image from the obtained image.

[0029] The reflective mirror type X-ray lens unit 150 has a Wolter type mirror set that can reflect X-rays in a first direction perpendicular to the X-ray irradiation direction and in a second direction perpendicular to the first direction, and forms an image of the X-rays that have passed through the sample S on the light-receiving surface of the high-resolution X-ray detector 190. This allows a two-dimensional high-resolution magnified image to be obtained. The magnification of the X-ray image is the value obtained by dividing the distance L1 from the sample to the lens surface formed by the reflective mirror type X-ray lens unit 150 by the distance L2 from the lens surface to the light-receiving surface.

[0030] The term "Wolter type" refers to a mirror set that includes mirrors with hyperbolic and ellipsoidal reflecting surfaces. The "Wolter type" allows for a wide imaging area. Each mirror has a reflecting surface formed with a multilayer film. Details of the multilayer film will be described later.

[0031] The high-resolution X-ray detector 190 is, for example, a CCD camera having a light receiving surface, and acquires the formed X-ray image. The high-resolution X-ray detector 190 preferably has a spatial resolution of 1 μm or less, and even better, 0.5 μm or less. This allows data of an enlarged image to be acquired with a high resolution of a pixel size of 50 nm or less, preferably 25 nm or less. The light intensity, i.e., the brightness of the observed image, is determined by the NA ２ / magnification ２ is proportional to.

[0032] 2(a) and 2(b) are a plan view and a front view, respectively, showing an example of the optical system of the imaging X-ray microscope 100. As shown in FIGS. 2(a) and 2(b), the imaging X-ray microscope 100 includes a condenser mirror 130.

[0033] The X-ray source 120 preferably generates X-rays with a focal spot size of 100 μm or less, and the condenser mirror 130 preferably focuses the generated X-rays into an irradiation area of ​​100 μm or less (FWHM: Full Width at Half Maximum). Furthermore, if the focal spot size of the X-ray source and the focused size in the irradiation area can be narrowed to 50 μm (FWHM) or less, the X-ray output entering the target field of view can be increased. This makes it possible, for example, to irradiate an irradiation area of ​​φ50 μm with X-rays having a photon dose of 10 photons / s or more. The focal spot size refers to the size of the effective focal spot as viewed from the X-ray beam side.

[0034] The condenser mirror 130 preferably has vertical and horizontal reflecting surfaces formed of a multilayer film, and irradiates monochromatic X-rays toward the sample S. The multilayer film allows the X-rays to be incident at a large angle on the mirror, and the large collection angle allows the formation of a fine focus of strong X-ray intensity.

[0035] 2(a) and 2(b), the reflective mirror type X-ray lens unit 150 includes imaging elements 160, 170, and 180, in this order from the sample S side. The imaging element 160 has a mirror set consisting of a first imaging mirror and a second imaging mirror that reflect vertically. The imaging element 170 has a first imaging mirror that reflects horizontally, and the imaging element 180 has a second imaging mirror that reflects horizontally. The imaging elements 170 and 180 form a horizontally reflecting mirror set. The distance D1 between the second imaging mirror that reflects horizontally and the sample S will be described later.

[0036] The first and second imaging mirrors for vertical reflection are both concave mirrors. These mirror sets form lens surfaces at positions where they overlap with the mirror sets. On the other hand, the first imaging mirror for horizontal reflection is a concave mirror, and the second imaging mirror for horizontal reflection is a convex mirror. These mirror sets form lens surfaces at positions upstream of the mirror sets. Then, by precisely machining the reflective surface of each mirror, the lens surfaces for vertical reflection and horizontal reflection can be made to coincide. Note that in the above example, a combination of concave-concave-convex mirrors is used from the perspective of compactness and aligning the lens surfaces, but other mirror arrangements and combinations may also be used.

[0037] 2(a) and 2(b), the distances D2, D3, D4, D5, and D6 on the optical axis from the sample S to the light-receiving surface are divided by the reflection positions of the imaging mirrors, and can be set to, for example, 30 to 60 mm, 30 to 60 mm, 50 to 100 mm, 50 to 100 mm, and 1 to 2.5 m. Note that the distance D2 is called the working distance and corresponds to the distance from the sample S to the first imaging mirror for vertical reflection. When placing the sample S and performing measurements, the user wants to maximize the working distance, but as will be described later, there are limitations in obtaining the required magnification and numerical aperture.

[0038] 2(a) and 2(b), a multilayer film is formed on the reflecting surfaces of the condenser mirror 130 and the imaging mirrors of each of the imaging elements 160 to 180. As a result, even with high-energy X-rays, not only can strong X-rays be irradiated onto the sample position with a large focusing angle, but the numerical aperture can also be increased, making it possible to obtain a magnified image of sufficient intensity even in a laboratory.

[0039] FIG. 3 is a schematic diagram showing the collection angle and aperture angle. The collection angle ψ is the maximum angle of the X-rays incident on the sample S from the condenser mirror relative to the optical axis. The aperture angle α is the maximum angle of the X-rays incident on the reflective mirror-type X-ray lens unit 150 from the sample S relative to the optical axis, and the numerical aperture NA is sin(α / 2). The collection angle ψ of the condenser mirror 130 and the numerical aperture NA of the reflective mirror-type X-ray lens unit 150 are determined depending on the radiation source. For example, for CuKα, the collection angle ψ is 10 mrad and the aperture angle α is 9.4 mrad, and for MoKα, the collection angle ψ is 5 mrad and the aperture angle α is 5 mrad. These determine the position of the sample S and the relationship between the distances D1 and D2. The intensity obtained on the high-resolution X-ray detector 190 as an X-ray microscope is approximately proportional to the square of the collection angle and aperture angle. Therefore, in laboratory equipment where it is difficult to obtain a strong X-ray source, it is desirable to make these as large as possible, and the effect of increasing the angle of incidence on the reflecting surface by using a multilayer film is extremely significant.

[0040] [Multilayer Film] Fig. 4 is a cross-sectional view showing a multilayer film. As shown in Fig. 4, the multilayer film is formed by alternately stacking layers formed of heavy elements and layers formed of light elements. In each multilayer film, a heavy element layer and a light element layer are repeatedly stacked as a pair of layers. The number of stacking may be set for each mirror constituting a mirror set.

[0041] The multilayer film selectively reflects X-rays with wavelengths corresponding to the characteristic X-rays from the incident X-rays. The periodic formation of heavy and light elements creates regular variations in electron density, resulting in the diffraction phenomenon. When the incident X-rays include continuous X-rays or multiple types of characteristic X-rays, the X-rays reflected by the multilayer film mirror become some or all of the characteristic X-rays diffracted by the multilayer film.

[0042] The multilayer spacing d is determined depending on the wavelength of the characteristic X-rays and the shape of the mirror (the shape of the curved reflecting surface, such as a parabolic shape or an elliptical shape). Therefore, the multilayer spacing is designed to be optimal depending on the type of target of the X-ray source 120 and the surface shape of the mirror.

[0043] 4, when θ1>θ2, the periodic length d1 at the position of the incident angle θ1 and the periodic length d2 at the position of the incident angle θ2 must satisfy the relationship d1<d2. The thickness (periodic length) of each layer is designed to vary with position, and accurate film formation according to the design is required during manufacturing.

[0044] By forming a multilayer film on the mirror surface, it is possible to increase the X-ray incidence angle, resulting in the realization of a compact focusing lens with a large collection angle and a compact imaging lens with a high numerical aperture.

[0045] Multilayer films can be formed, for example, by generating plasma, directing it at a target, and depositing the resulting particles on a substrate. A slit is installed to narrow the resulting particles, and the amount of particles reaching the substrate, i.e., the film thickness, can be adjusted by changing the shape of the opening. Alternatively, by changing the speed of the substrate passing near the slit, the layer thickness can be made thinner where the substrate moves quickly and thicker where it moves slowly. By combining these methods, thin films with different thicknesses in different locations can be deposited with high precision. Note that heavy elements such as tungsten and molybdenum can be used, while light elements such as silicon, carbon, and boron can be used.

[0046] The multilayer film is preferably formed with an error of 0.5 Å or less from the designed periodicity, and even better, an error of 0.2 Å or less. Nonuniformity in the shape and periodic structure of the optical element causes disturbances in the wavefront of X-rays. When forming a multilayer film, by forming it so that the positional periodicity error and surface shape error are small from the design value, it is possible to reduce the disturbance in the wavefront of X-rays reflected by the formed reflecting surface. This makes it possible to obtain X-ray images with sufficiently high resolution without phase shift over the entire lens surface when imaging using hard X-rays.

[0047] For example, by adopting a reflective imaging lens coated with such a multilayer film, it is possible to achieve an angular aperture of more than 8 mrad even when using 8 keV X-rays, which are commonly used in laboratories, and even when using 17.5 keV X-rays, it is possible to achieve an angular aperture of more than 5 mrad and a lens with an efficiency of over 40%.

[0048] [Multilayer Film Accuracy Test] Multilayer films were prepared for each imaging mirror used in the imaging X-ray microscope 100. The multilayer films were manufactured by RIT (Rigaku Innovative Technologies, Inc.). The film-forming equipment used to manufacture the multilayer films was one that had achieved high film-forming stability, reproducibility, and film thickness controllability through multiple calibrations. The periodic length versus position of each obtained multilayer film was measured with high precision using X-ray reflectivity.

[0049] 5(a) and (b) are plan views showing a vertical reflection mirror set and a horizontal reflection mirror set, respectively. As shown in Fig. 5(a), the first imaging mirror 161 and the second imaging mirror 162 in the vertical reflection imaging element 160 are formed with a hyperbolic and an ellipsoidal multilayer film, respectively. Also, as shown in Fig. 5(b), the first imaging mirror 171 and the second imaging mirror 181 in the horizontal reflection imaging element 170 and the imaging element 180 are formed with an ellipsoidal and a hyperbolic multilayer film, respectively.

[0050] Figure 6 is a graph showing the design and measured values ​​of the periodic length of the multilayer film versus the position of the first imaging mirror for vertical reflection. Figure 7 is a graph showing the design and measured values ​​of the periodic length of the multilayer film versus the position of the second imaging mirror for vertical reflection. Figure 8 is a graph showing the design and measured values ​​of the periodic length of the multilayer film versus the position of the first imaging mirror for horizontal reflection. Figure 9 is a graph showing the design and measured values ​​of the periodic length of the multilayer film versus the position of the second imaging mirror for horizontal reflection.

[0051] In each figure, the straight lines represent the design values ​​of the periodic length according to position, and the circles represent the measured values ​​of the periodic length for each position. The error in the periodic length of the multilayer film of each imaging mirror was within 0.2 Å.

[0052] Figure 10 is a graph showing the magnitude of the error in the surface shape of the horizontally reflective second imaging mirror versus its position. As shown in Figure 10, the error in the surface shape of the horizontally reflective second imaging mirror was within 1.5 nm. Similar results were obtained for the surface shapes of the other mirrors as well.

[0053] [Evaluation of X-ray image resolution] An imaging X-ray microscope 100 was assembled using mirrors manufactured with the above-mentioned multilayer film precision. A CuKα X-ray source was used. The detailed specifications of the mirror set constituting the reflective mirror type X-ray lens unit 150 are as shown in the table below.

[0054] The high-resolution X-ray detector 190 used was a high-resolution X-ray camera XsightXRM manufactured by Rigaku. An X-ray image of a test chart for resolution evaluation was taken as a sample. A thick-film, high-resolution X-ray chart (XRESO-50HC, minimum dimension 50 nm, pattern height 500 nm) manufactured by NTT-AT was used as the test chart for resolution evaluation. The calculated pixel resolution of the X-ray image was 12 nm. The relationship between the magnification of the reflective mirror-type X-ray lens unit 150, the spatial resolution of the high-resolution X-ray detector 190, and the pixel resolution of the X-ray image is shown in Table 2 below.

[0055] 11(a) is a diagram showing an X-ray image of a test chart with a line width of 50 nm for resolution evaluation. Fig. 11(b) is a diagram showing an X-ray image of a star chart with a center line width of 50 nm for resolution evaluation. In both X-ray images, it is possible to distinguish charts down to 50 nm in size, providing sufficient resolution for inspecting the microstructure of semiconductor devices.

[0056] 12(a) and (b) show an X-ray image of the 100-nm hole chart and its partial intensity distribution (line profile), respectively. As shown in the figure, holes with a diameter of 100 nm are regularly arranged at intervals of 200 nm, and it was confirmed that there are subtle differences between each hole.

[0057] [Semiconductor Inspection Apparatus] A semiconductor inspection apparatus that applies the imaging X-ray microscope 100 described above will now be described. FIG. 13 is a schematic diagram showing an example of application of the imaging X-ray microscope 100 to a semiconductor inspection apparatus. The basic configuration of the imaging X-ray microscope 100 shown in FIG. 13 is the same as that shown in FIG. 1. However, a configuration that is more suitable for a semiconductor inspection apparatus may be adopted depending on the characteristics of the sample S1 and circumstances specific to the inspection process. Note that the semiconductor inspection apparatus can be used not only for the purpose of quality inspection in the inspection process of manufactured semiconductors, but also for inspection in laboratories during research and development.

[0058] The imaging X-ray microscope 100 has a high resolution of 100 nm or less, preferably 50 nm or less, and can be applied to processes for inspecting semiconductor microstructures for defects. The imaging X-ray microscope 100 can emit X-rays of 15 keV or more from the X-ray source 120, allowing X-ray images to be acquired by transmitting them through a silicon substrate. In particular, from the perspective of ease of configuration, it is preferable to use MoKα of 17.5 keV. This allows for the observation of structures buried at a depth of 10 μm or more from the surface of a semiconductor sample. Furthermore, since the absorption coefficient at each position can be measured using the X-ray transmittance, the amount of material introduced into each hole, for example, by a CVD method, can be measured, allowing for quantitative evaluation of the effectiveness of the CVD method. Furthermore, structures such as the size and shape of deep holes and grooves in areas not visible from the surface, as well as variations in their placement, can be directly observed.

[0059] The sample S1 used in the semiconductor inspection process is a silicon wafer formed in a flat plate shape (e.g., 300 mm in diameter). Therefore, when performing CT imaging, it is expected that 360° rotation may be difficult. In such cases, it is necessary to rotate the sample S1 within a limited angle. For example, the sample S1 can be rotated within a range of ±5° or more, allowing the wafer sample to be tilted for measurement. This allows for observation of depth-dependent structural changes.

[0060] It is empirically known that the overall size of the equipment installed at semiconductor manufacturing and inspection sites is no problem if it is 4 m or less. When applying the imaging X-ray microscope 100 to a semiconductor inspection device, it is preferable that the distance on the optical axis from the sample S1 to the light-receiving surface of the high-resolution X-ray detector 190 be 3 m or less. This allows for the construction of a compact semiconductor inspection device. Furthermore, it can be stored in the limited storage space of an inspection room, making it easy to incorporate into existing inspection processes.

[0061] Furthermore, it is preferable that the aperture angle of the reflective mirror type X-ray lens unit 150 is 5 mrad or more, which makes it possible to shorten the distance from the sample S1 to the light receiving surface of the high-resolution X-ray detector 190, thereby realizing a compact semiconductor inspection device.

[0062] [Semiconductor Inspection System] Fig. 14 is a block diagram showing a semiconductor inspection system 10. The semiconductor inspection system 10 includes a semiconductor inspection device 200 and a processing device 300. The processing device 300 functions as a control device that controls the operation of the semiconductor inspection device 200 or as an analyzer for measurement data obtained from the semiconductor inspection device 200. In the example shown in Fig. 14, the semiconductor inspection system 10 is made up of multiple devices, but the functions of each device may be integrated into a single device.

[0063] (Semiconductor Inspection Apparatus) The semiconductor inspection apparatus 200 includes an imaging X-ray microscope 100, a control unit 250, and a position adjustment mechanism 270. The imaging X-ray microscope 100 is configured as described above, and each mirror constituting the condenser mirror 130 and the reflective mirror-type X-ray lens unit 150 has a reflective surface coated with a multilayer film that has high reflectivity for X-rays of a specific wavelength. This allows the numerical aperture to be increased even for high-energy X-rays by maintaining a high X-ray incidence angle, thereby enabling the acquisition of a magnified image of sufficient intensity within a size that can be stored in a laboratory. As a result, localized microstructures inside semiconductors can be inspected nondestructively.

[0064] Accurate alignment is possible by providing the control unit 250 and the position adjustment mechanism 270. The control unit 250 controls the operation of the imaging X-ray microscope 100 in response to control instructions from the processing device 300.

[0065] For example, the control unit 250 adjusts the relative position of the sample S1 with respect to each part of the imaging X-ray microscope 100 using the position adjustment mechanism 270. These parts include the X-ray irradiation part 110, the X-ray source 120, the condenser mirror 130, the aperture 135, the reflective mirror-type X-ray lens part 150, the imaging elements 160 to 180, and the high-resolution X-ray detector 190, which enable focal position adjustment and sample position adjustment. The control unit 250 can also change the voltage supplied to the X-ray irradiation part 110 to change the X-ray intensity.

[0066] The position adjustment mechanism 270 is a mechanism that adjusts the relative position of the sample S1 with respect to each part of the imaging X-ray microscope 100 under automatic or operator-controlled control. Specifically, it includes a sample adjustment mechanism using a sample stage, measurement position movement (alignment), and focal position adjustment. This mechanism can, for example, move the sample position on the optical axis closer to or farther away from the high-resolution X-ray detector 190. The position adjustment mechanism 270 can also rotate the rotation stage. Note that the configuration shown in FIG. 14 is merely an example, and a configuration in which the operation of the imaging X-ray microscope 100 is manually adjusted without the control unit 250 or position adjustment mechanism 270 may also be employed.

[0067] (Processing Device) The processing device 300 functions as a control device to control the operation of the imaging X-ray microscope 100, acquires X-ray images, and analyzes the acquired X-ray images as an analyzing device. The functions of the processing device 300 are mainly realized by a computer 310.

[0068] The computer 310 is, for example, a PC, and is configured with a processor that executes processing, and a memory or a hard disk that stores programs and data, etc. The computer 310 is connected to an input device 380 such as a keyboard or a mouse, and an output device 390 such as a display, and receives input from the user through the input device 380, and outputs an input screen, an X-ray image, a graph, analysis results, etc. to the output device 390.

[0069] The computer 310 may be a server device located on the cloud. In addition, from the viewpoint of processing load, the function of controlling the operation of the imaging X-ray microscope 100 and the function of analyzing the measurement data may be separated, with the control being performed by a PC installed on-site and the analysis being performed by a server device.

[0070] The computer 310 includes an input / output control unit 311, a measurement control unit 315, a measurement data storage unit 317, and an analysis unit 319. Each unit can send and receive information via a control bus L.

[0071] The input / output control unit 311 receives input from the input device 380 and controls output to the output device 390. The input / output control unit 311 can receive, for example, input of measurement conditions. Examples of measurement conditions include the intensity of the generated X-rays, the X-ray irradiation position, the position of the sample, the arrangement of the detector, and the measurement time when acquiring the X-ray image. The input / output control unit 311 can also output the obtained X-ray images and analysis results.

[0072] The measurement control unit 315 controls the operations for measurement by the imaging X-ray microscope 100. The controlled operations include the arrangement of each part, adjustment of the relative position of the sample, and generation of X-rays. Control instructions are sent to the control unit 250 in the semiconductor inspection equipment 200, which controls each part of the imaging X-ray microscope 100.

[0073] The measurement data storage unit 317 stores, as measurement data, the X-ray image acquired by the imaging X-ray microscope 100. The stored measurement data can be used for displaying the X-ray image on a screen for observation and for analyzing the data.

[0074] The analysis unit 319 analyzes the obtained measurement data. For example, the analysis unit 319 quantitatively evaluates the surface density of the material based on the absorption coefficient at each position. Based on this quantitative evaluation, the presence or absence of defects in the sample can be determined. The analysis unit 319 can also evaluate the depth of holes inside the semiconductor and the state of materials deposited by the CVD method.

[0075] (Sample) The sample S1 has a substrate on which a semiconductor circuit is formed. The semiconductor inspection device 200 is particularly effective for inspecting semiconductors in which structures of several tens of nanometers parallel to the surface are formed over a depth of several micrometers. It is also effective in cases in which the sample S1 has a semiconductor device layer provided on a substrate, in that it can measure the internal microstructure nondestructively. The semiconductor device layer can be formed of, for example, various metals or silicon compounds.

[0076] The semiconductor inspection device 200 is also effective when the sample S1 is a plate-like body having a thickness of 500 μm or more. By using the semiconductor inspection device 200, a magnified image with sufficient intensity can be obtained, making inspection possible.

[0077] [Semiconductor Inspection Method] Semiconductor inspection can be performed nondestructively using the semiconductor inspection system 10 described above. In this case, a sample is first placed in the sample holder 140. While sample placement is preferably performed using an automated transport device such as a robot arm or a belt conveyor for efficiency reasons, it can also be performed manually. Furthermore, sample placement refers to either or both of fixing the semiconductor sample to the sample stage and aligning the semiconductor sample on the sample stage to the X-ray irradiation position. Next, X-rays of 15 keV or higher are irradiated onto the sample S1. The resulting X-ray image is then used to evaluate the presence or absence of defects within the sample. In this way, a magnified image with sufficient intensity and a size that can be stored in a laboratory can be obtained, enabling the microstructure inside the semiconductor to be inspected locally. Note that evaluation also includes visual evaluation of the X-ray image by a user.

[0078] [Example] The scale parallel to the surface of a semiconductor device with deep holes is approximately several tens of nanometers to a hundred nanometers. From the X-ray chart images shown in Figures 11 and 12, it was demonstrated that the X-ray microscope of the present invention can clearly separate a 50-nm linewidth structure and individual 100-nm holes. Furthermore, as shown by the intensity chart results in Figure 12(b), it was confirmed that there are subtle differences between each hole.

[0079] Note that this application claims priority based on Japanese Patent Application No. 2022-071044 filed on April 22, 2022, and the entire contents of Japanese Patent Application No. 2022-071044 are incorporated by reference into this application.

[0080] 10 Semiconductor inspection system 100 Imaging type X-ray microscope 110 X-ray irradiation unit 120 X-ray source 130 Condenser mirror 135 Aperture 140 Sample holder 150 Reflecting mirror type X-ray lens unit 160 to 180 Imaging element 190 High resolution X-ray detector (imaging unit) 200 Semiconductor inspection device 250 Control unit 270 Position adjustment mechanism 300 Processing device 310 Computer 311 Input / output control unit 315 Measurement control unit 317 Measurement data storage unit 319 Analysis unit 380 Input device 390 Output device L Control bus D1 to D6 Distance L1, L2 Distance S, S1 Sample d1, d2 Periodic length

Claims

1. A semiconductor inspection device using a magnified X-ray image, an X-ray irradiation unit including a fine-focus, high-output X-ray source and a condenser mirror for focusing and irradiating the emitted X-rays toward a semiconductor sample; A sample holder for holding the sample; a reflection mirror type X-ray lens unit that forms an image of the X-rays transmitted through the sample; an imaging unit for acquiring the formed X-ray image, A semiconductor inspection device, wherein each of the mirrors constituting the condenser mirror and the reflective mirror type X-ray lens unit has a reflective surface on which a multilayer film having a high reflectance for X-rays of a specific wavelength is formed.

2. 2. The semiconductor inspection apparatus according to claim 1, wherein the sample comprises a substrate on which a semiconductor circuit is formed, and a semiconductor device layer provided on the substrate.

3. 3. A semiconductor inspection device according to claim 1, wherein the sample is a plate-like body having a thickness of 500 [mu]m or more.

4. 3. The semiconductor inspection device according to claim 1, wherein a distance on the optical axis from the sample to the light receiving surface of the imaging section is 3 m or less.

5. 3. The semiconductor inspection device according to claim 1, wherein the aperture angle of said reflecting mirror type X-ray lens portion is 5 mrad or more.

6. 3. The semiconductor inspection device according to claim 1, further comprising a position adjustment mechanism capable of adjusting the relative position of the sample with respect to each part under automatic or manual control.

7. A semiconductor inspection device according to claim 1 or 2, A control device connected to the semiconductor inspection device, The semiconductor inspection system according to the present invention, wherein the control device adjusts the relative position of the sample with respect to each part in the semiconductor inspection device automatically or based on an instruction from a user.

8. A semiconductor inspection device according to claim 1 or 2, an analysis device connected to the semiconductor inspection device, A semiconductor inspection system, wherein the analysis device quantitatively evaluates the surface density of a substance at each position based on an absorption coefficient in an X-ray image acquired by the semiconductor inspection device.

9. A semiconductor inspection device according to claim 1 or 2, an analysis device connected to the semiconductor inspection device, The semiconductor inspection system is characterized in that the analysis device evaluates a structure relating to a hole formed in the sample based on an absorption coefficient in an X-ray image acquired by the semiconductor inspection device.

10. 10. The semiconductor inspection system of claim 9, wherein the X-ray image is measured with the sample tilted.

11. A semiconductor inspection method performed non-destructively using the semiconductor inspection apparatus according to claim 1 or 2, comprising: placing the sample on the sample holder; irradiating the sample with X-rays of 15 keV or more; and evaluating the presence or absence of defects in the sample based on the formed X-ray image.

Images