Semiconductor inspection apparatus, semiconductor inspection system, and semiconductor inspection method

Abstract

Provided are a semiconductor inspection device, a semiconductor inspection system, and a semiconductor inspection method that can inspect a microstructure inside a semiconductor for each part by obtaining a magnified image with sufficient strength and a size that can be housed in a laboratory. A semiconductor inspection device using an amplified X-ray image is provided with: an X-ray irradiation unit comprising a micro-focus and high-output X-ray source (120) and a convergent mirror (130) that condenses and irradiates emitted X-rays toward a semiconductor sample; a sample holding unit that holds the sample; a mirror-type X-ray lens unit (150) that forms an image of the X-rays that have passed through the sample; and an imaging unit (190) for acquiring an X-ray image, in which each mirror constituting the convergent mirror (130) and the mirror-type X-ray lens unit (150) has a reflective surface on which a multilayer film having a high reflectance with respect to X-rays having a specific wavelength is formed.

Description

Technical Field

[0001] The present invention relates to a semiconductor inspection device, a semiconductor inspection system and a semiconductor inspection method using an enlarged X-ray image. Background Art

[0002] In recent years, the high degree of integration of semiconductor circuits has been promoted, and semiconductors have been developed in which fine structures in the direction parallel to the surface are further formed deeper in the thickness direction. The surface structure of such semiconductors and the internal structure processed by etching have become difficult to inspect using the optical inspection methods, CD-SEM (Critical Dimension Scanning Electron Microscope) and the like that have been performed in the past. Therefore, in the case of wanting to inspect the shape and size of a hole that is longer in the thickness direction, a destructive inspection such as a cross-sectional SEM or TEM is required. However, the management of semiconductor manufacturing processes strongly requires non-destructive inspection methods. As one of them, there is a method of structurally analyzing the pattern of X-rays scattered from small angles of an average structure of an area with a diameter of about several hundred μm by transmission SAXS (small-angle X-ray scattering). However, in such a method, even if the averaged structure can be inspected, it is impossible to inspect defects in each structure like a microscope.

[0003] On the other hand, in conventional imaging X-ray microscopes, the imaging system mostly uses a Fresnel zone plate lens (FZP) (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 is significantly reduced. For example, when using FZP to image X-rays above 15 keV, the efficiency is less than a few percent. In addition, the numerical aperture (NA) in this case is also around 1×10 -3 Therefore, it is difficult to realize high-resolution X-ray microscopy using high-energy X-rays in laboratories.

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

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: U.S. Patent No. 7394890

[0008] Patent Document 2: Japanese Patent No. 6478433 Summary of the invention

[0009] Problem that the invention aims to solve

[0010] In the field of semiconductor manufacturing, semiconductor devices have been developed in which structures of tens of nanometers in the direction parallel to the surface extend over several micrometers in the depth direction. However, conventional inspection devices cannot inspect complex structures inside deep hole structures in a non-destructive manner.

[0011] In the X-ray microscope described in Patent Document 2, since the total reflection of X-rays is used, the incident angle must be limited to below the critical angle, and in order to realize a lens with a large numerical aperture, the size of the X-ray beam direction needs to be lengthened. In the application field of X-ray microscopes, it is particularly desired to image high-energy X-rays with high efficiency in a size that can be installed in a laboratory.

[0012] The present invention is completed in view of such a situation, and its purpose is to provide a semiconductor inspection device, a semiconductor inspection system and a semiconductor inspection method, which can inspect the fine structure inside the semiconductor for each part by obtaining a magnified image with a size that can be accommodated in a laboratory and with sufficient intensity.

[0013] Solutions for solving problems

[0014] (1) In order to achieve the above-mentioned purpose, the semiconductor inspection device of the present invention is a semiconductor inspection device that uses a magnified X-ray image, characterized in that it comprises: an X-ray irradiation unit, which is composed of a micro-focus and high-output X-ray source and a converging mirror that focuses the emitted X-rays toward a semiconductor sample for irradiation; a sample holding unit, which holds the sample; a reflector-type X-ray lens unit, which images the X-rays transmitted through the sample; and an imaging unit, which obtains the imaged X-ray image, wherein each mirror constituting the converging mirror and the reflector-type X-ray lens unit has a reflecting surface formed with a multilayer film having a high reflectivity for X-rays of a specific wavelength.

[0015] (2) In the semiconductor inspection apparatus described in (1) above, the sample includes a substrate on which a semiconductor circuit is formed and a semiconductor device layer provided on the substrate.

[0016] (3) In the semiconductor inspection apparatus described in (1) or (2) above, the sample is a plate-like body having a thickness of 500 μm or more.

[0017] (4) In addition, 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.

[0018] (5) In the semiconductor inspection device described in any one of (1) to (4) above, the aperture angle of the reflector type X-ray lens unit is 5 mrad or more.

[0019] (6) In addition, in any one of the semiconductor inspection devices described in (1) to (5) above, it is characterized in that it also has: a position adjustment mechanism that can accept automatic or operation-based control to adjust the relative position of the sample with respect to each part.

[0020] (7) In addition, the semiconductor inspection system of the present invention is characterized in that it comprises: a semiconductor inspection device as described in 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 in the semiconductor inspection device automatically or based on instructions from a user.

[0021] (8) In addition, the semiconductor inspection system of the present invention is characterized in that it comprises: a semiconductor inspection device as described in 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 the material at each position based on the absorption coefficient in the X-ray image obtained by the semiconductor inspection device.

[0022] (9) In addition, the semiconductor inspection system of the present invention is characterized in that it comprises: a semiconductor inspection device as described in (1) or (2) above; and an analysis device connected to the semiconductor inspection device, wherein the analysis device evaluates a structure related to a hole formed in the sample based on an absorption coefficient in an X-ray image obtained by the semiconductor inspection device.

[0023] (10) In addition, in the semiconductor inspection system described in (9) above, the X-ray image is measured by tilting the sample.

[0024] (11) In addition, the semiconductor inspection method of the present invention is a semiconductor inspection method performed in a non-destructive manner using the semiconductor inspection device described in any one of (1) to (6) above, and is characterized in that it includes: a step of setting the sample in the sample holding portion; a step of irradiating the sample with X-rays of 15 keV or more; and a step of evaluating the presence or absence of defects in the sample through the imaged X-ray image. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram showing an imaging type X-ray microscope.

[0026] Figure 2 (a) and (b) are respectively a top view and a front view showing the optical system of the imaging type X-ray microscope.

[0027] Figure 3 It is a schematic diagram showing the focusing angle and aperture angle.

[0028] Figure 4 is a cross-sectional view showing a multilayer film.

[0029] Figure 5 (a) and (b) are top views showing a mirror group for vertical reflection and a mirror group for horizontal reflection, respectively.

[0030] Figure 6 It is a graph showing the design value and measured value of the period length of the multilayer film with respect to the position of the first imaging mirror of vertical reflection.

[0031] Figure 7 It is a graph showing the design value and measured value of the period length of the multilayer film with respect to the position of the second imaging mirror for vertical reflection.

[0032] Figure 8 It is a graph showing the design value and measured value of the period length of the multilayer film with respect to the position of the first imaging mirror of horizontal reflection.

[0033] Fig. 9 It is a graph showing the design value and the measured value of the period length of the multilayer film with respect to the position of the second imaging mirror of horizontal reflection.

[0034] Fig.10 : is a graph showing the magnitude of the error in the surface shape with respect to the position of the second imaging mirror of the horizontal reflection.

[0035] Fig.11 (a) and (b) are diagrams showing X-ray images of a 50 nm line and space chart (L&S chart) and a 50 nm star chart (starchart), respectively.

[0036] Fig.12 (a) and (b) are diagrams showing an X-ray image of a 100 nm hole chart and intensity distribution of a part thereof, respectively.

[0037] Fig.13 This is a schematic diagram showing an application example in which the imaging X-ray microscope of the present invention is applied to a semiconductor inspection device.

[0038] Fig.14is a block diagram showing a semiconductor inspection system of the present invention. DETAILED DESCRIPTION

[0039] Next, embodiments of the present invention will be described with reference to the accompanying drawings. In order to facilitate understanding of the description, the same components are denoted by the same reference numerals in the drawings, and repeated descriptions are omitted.

[0040] The imaging type X-ray microscope described below can be used in the semiconductor inspection apparatus of the present invention. First, the imaging type X-ray microscope is described, and its application to semiconductor inspection will be described later.

[0041] [Imaging X-ray Microscope]

[0042] Figure 1 This is a schematic diagram of an imaging type X-ray microscope 100. The imaging type X-ray microscope 100 is composed of a high-brightness X-ray source 120, a condenser mirror 130, a sample holding portion 140, a mirror type X-ray lens portion 150, and a high-resolution X-ray detector 190 (camera portion). A multilayer film is formed on the X-ray reflector used in the condenser mirror 130 and the mirror type X-ray lens portion 150. The reflection surface formed by the multilayer film has a high reflectivity for X-rays of a specific wavelength, and the numerical aperture can be increased by keeping the X-ray incident angle high, so a high-resolution X-ray magnified image can be obtained in a short time. In addition, the resolution δ of the imaging type X-ray microscope 100 can be expressed as δ=kλ / NA using a constant k, the wavelength λ of the irradiated X-rays, and the numerical aperture NA.

[0043] Such an imaging X-ray microscope 100 is highly useful, for example, in the inspection of semiconductor devices that are miniaturized and highly densified by forming structures of tens of nm in scale into a thickness of several μm. If the product wafer can be observed or inspected in a non-destructive manner by the imaging X-ray microscope 100, the productivity in device manufacturing can be greatly improved. In addition, for example, in the field of life science research, the imaging X-ray microscope 100 can be used to observe parts of 50nm to 1μm in size. Specifically, the internal structures of cell organelles, cells, tissues, organs, and organ systems, the morphology of model cells, disease model cells, and the morphology of mutant parts of transgenic animals can be listed. Through the X-ray microscope, CT tomographic images of 50nm to 1μm in size can be observed, and three-dimensional observation can be performed directly without thinning thick cells.

[0044] The X-ray irradiation unit 110 has an X-ray source 120, a converging mirror 130, and an aperture 135, and irradiates micro-focus and high-output X-rays toward the sample. The X-ray source 120 is preferably a micro-focus high-output X-ray source of a rotating cathode type. The irradiated X-rays preferably have an energy of 4 keV or more. The energy of the X-rays is inversely proportional to the wavelength, and the higher the energy, the shorter the wavelength. Therefore, by using X-rays with short wavelengths in this way, the theoretical limit of the resolution δ of the imaging type X-ray microscope 100 can be increased. As targets of the X-ray source that specify the wavelength of the X-rays, for example, chromium (Cr), copper (Cu), molybdenum (Mo), and silver (Ag) can be listed.

[0045] The X-ray source 120 preferably generates X-rays with an output of 500W or more, and preferably 1kW or more. This can increase the intensity of the irradiated X-rays. The design of the converging mirror 130 is optimized so that the generated X-rays are focused onto a tiny irradiation area at an optimal focusing angle for the numerical aperture of the X-ray lens. In addition, a multilayer film having a high reflectivity for X-rays of the required wavelength is formed on the mirror surface. The details of the construction of the multilayer film will be described later. In addition, in this specification, "having a high reflectivity" means the same as "when the intensity of the incident characteristic X-ray is set to 100%, the intensity of the characteristic X-ray reflected by the mirror at each reflection is 70% or more."

[0046] The aperture 135 can control the aperture in the first direction and the second direction perpendicular to the X-ray irradiation direction, and adjust the size of the X-rays in each direction to the sample S. In this embodiment, the first direction indicates the vertical direction and the second direction indicates the horizontal direction, but the present invention is not necessarily limited thereto.

[0047] The sample holding section 140 includes a rotating stage that can be rotationally controlled with high precision, and holds the sample S. The sample S can also be reconstructed from the obtained stereoscopic image by photographing the sample S while rotating it on the rotating stage.

[0048] The reflector type X-ray lens unit 150 has a Wolter type mirror group that can reflect in a first direction perpendicular to the X-ray irradiation direction and a second direction perpendicular to the first direction, and forms an image of the X-rays transmitted through the sample S on the light receiving surface of the high-resolution X-ray detector 190. Thus, a two-dimensional high-resolution magnified image can be obtained. The value obtained by dividing the distance L1 from the sample to the lens surface formed by the reflector type X-ray lens unit 150 by the distance L2 from the lens surface to the light receiving surface is the magnification of the X-ray image.

[0049] The so-called "Wolter type" means that the mirror group includes a mirror having a hyperbolic surface and an elliptical surface. By being a "Wolter type", a wider area for imaging can be obtained. Each mirror has a reflecting surface formed by a multilayer film. The details of the multilayer film will be described later.

[0050] The high-resolution X-ray detector 190 is, for example, a CCD camera having a light-receiving surface, and acquires the imaged X-ray image. The high-resolution X-ray detector 190 preferably has a spatial resolution of 1 μm or less, and more preferably 0.5 μm or less. Thus, it is possible to acquire the data of the magnified image at a high resolution with a pixel size of 50 nm or less, preferably 25 nm or less. In addition, the light intensity, i.e., the brightness of the observed image, is related to the NA. 2 / magnification 2 Directly proportional.

[0051] [Light-gathering system and imaging system]

[0052] Figure 2 (a) and (b) are respectively a top view and a front view showing an example of the optical system of the imaging type X-ray microscope 100. Figure 2 As shown in (a) and (b) of FIG. 1 , the imaging type X-ray microscope 100 includes a converging lens 130 .

[0053] The X-ray source 120 generates X-rays with a focal spot size of less than 100 μm, and the converging lens 130 preferably focuses the generated X-rays to an irradiation area of ​​less than 100 μm (FWHM). Furthermore, if the focal spot size of the X-ray source and the focusing size in the irradiation area can be narrowed to less than 50 μm (FWHM), the X-ray output entering the target field of view can be increased. Thus, for example, a photon quantity of 10 9 Photons / s or more X-rays. In addition, the focal spot size refers to the size of the effective focal spot as viewed from the X-ray beam side.

[0054] The converging mirror 130 preferably has vertical and horizontal reflection surfaces formed of a multilayer film, and irradiates monochromated X-rays toward the sample S. The multilayer film can increase the incident angle of X-rays to the mirror, and a micro focus with strong X-ray intensity can be formed by a large focusing angle.

[0055] exist Figure 2In the examples shown in (a) and (b), as a reflector type X-ray lens unit 150, imaging elements 160, 170 and 180 are provided in order from the sample S side. The imaging element 160 has a mirror group consisting of a first imaging mirror for vertical reflection and a second imaging mirror. The imaging element 170 has a first imaging mirror for horizontal reflection, and the imaging element 180 has a second imaging mirror for horizontal reflection. The imaging elements 170 and 180 constitute a mirror group for horizontal reflection. The distance D1 between the second imaging mirror for horizontal reflection and the sample S will be described later.

[0056] The first imaging mirror and the second imaging mirror for vertical reflection are both concave mirrors. Their mirror groups form lens surfaces at positions overlapping with the mirror groups. 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. Their mirror groups form lens surfaces at positions preceding the mirror groups. Furthermore, by precisely machining the reflection surfaces of each mirror, the lens surface for vertical reflection can be made consistent with the lens surface for horizontal reflection. In addition, in the above example, a combination of concave-concave-convex mirrors is adopted from the viewpoint of compactness and making the lens surfaces consistent, but a combination of other mirror configurations may also be adopted.

[0057] exist Figure 2 In the examples shown in (a) and (b), the distances D2, D3, D4, D5, and D6 obtained by dividing the distance on the optical axis from the sample S to the light-receiving surface according to the reflection position of each imaging mirror 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. In addition, the distance D2 is called the working distance, which is equivalent to the distance from the sample S to the first imaging mirror of the vertical reflection. Although the user hopes to make the working distance as large as possible when configuring the sample S and performing the measurement, there are limitations in obtaining the required magnification and numerical aperture as described later.

[0058] exist Figure 2 In the examples shown in (a) and (b), a multilayer film is formed on the reflecting surface of any imaging mirror of the condensing mirror 130 and each imaging element 160 to 180. As a result, even with high-energy X-rays, not only can strong X-rays be irradiated to the sample position at a large focusing angle, but also the numerical aperture can be increased, and a magnified image of sufficient intensity can be obtained in the laboratory.

[0059] Figure 3: is a schematic diagram showing the focusing angle and the aperture angle. The focusing angle ψ is the maximum angle of the X-ray incident on the sample S from the converging mirror relative to the optical axis. The aperture angle α is the maximum angle of the X-ray incident on the reflector 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 focusing angle ψ of the converging mirror 130 and the numerical aperture NA to the reflector type X-ray lens unit 150 are determined according to each ray source. For example, for CuKα, the focusing angle ψ is 10mrad and the aperture angle α is 9.4mrad, and for MoKα, the focusing angle ψ is 5mrad and the aperture angle α is 5mrad. Thus, the position of the sample S is determined, and the relationship between the distances D1 and D2 is determined. As an X-ray microscope, the intensity that can be obtained on the high-resolution X-ray detector 190 is approximately proportional to the square of the focusing angle and the aperture angle. Therefore, in laboratory devices where it is difficult to obtain a strong X-ray source, it is desirable to make them as large as possible, and a multilayer film is extremely effective in increasing the incident angle to the reflection surface.

[0060] [Multilayer film]

[0061] Figure 4 is a cross-sectional view showing a multilayer film. Figure 4 As shown in FIG. 1 , a multilayer film is formed by alternately stacking layers formed by heavy elements and layers formed by light elements. In each multilayer film, the heavy element layer and the light element layer are repeatedly stacked as a pair of layers. The number of stacking times can be set for each mirror constituting the mirror group.

[0062] The multilayer film selectively reflects the X-rays of the corresponding characteristic X-ray wavelength from the incident X-rays. The periodic formation of heavy elements and light elements produces regular density of electrons, resulting in diffraction. When the incident X-rays contain continuous X-rays or multiple types of characteristic X-rays, the X-rays reflected by the multilayer film mirror become part or all of the characteristic X-rays diffracted by the multilayer film.

[0063] The multilayer spacing d is determined by the wavelength of characteristic X-rays and the shape of the mirror (curved reflection surface such as parabola or ellipse). Therefore, the optimal multilayer spacing is designed according to the type of target of the X-ray source 120 and the surface shape of the mirror.

[0064] exist Figure 4 In the example shown, the period length d1 at the position of the incident angle θ1 and the period length d2 at the position of the incident angle θ2 need to have a relationship of d1<d2 when θ1>θ2. The thickness (period length) of each layer is designed to vary depending on the position, and accurate film formation as designed is required during manufacturing.

[0065] By forming a multilayer film on the mirror surface, the X-ray incident angle can be increased. As a result, a compact condenser lens with a large condensing angle and a compact imaging lens with a high numerical aperture can be realized.

[0066] For example, a multilayer film can be formed by generating plasma and stacking particles generated by causing the plasma to hit a target on a substrate. In this case, a slit can be provided to narrow the generated particles, and the amount of particles reaching the substrate, i.e., the film thickness, can be adjusted according to the shape of its aperture. Alternatively, by changing the speed of the substrate passing near the slit, the layer thickness can be made thinner when the substrate moves quickly, and the layer thickness can be made thicker when the substrate moves slowly. These methods can be combined to form a thin film with different film thicknesses in each location with high precision. In addition, tungsten and molybdenum can be used as heavy elements, and silicon, carbon, boron, etc. can be used as light elements.

[0067] The multilayer film is preferably designed with a periodicity of The following error is formed, if The following errors are better. The shape of the optical element and the non-uniformity of the periodic structure will cause disturbance in the wavefront of the X-ray. In the case of forming a multilayer film, by forming it so that the periodic error caused by the position and the error of the surface shape are reduced relative to the design value, the disturbance of the wavefront of the X-ray reflected on the formed reflection surface can be reduced. As a result, in the shooting using hard X-rays, an X-ray image with no phase deviation and sufficiently high resolution can be obtained on the entire surface of the lens.

[0068] For example, by using a reflective imaging lens coated with such a multilayer film, the aperture angle can be made larger than 8 mrad even when using 8 keV X-rays commonly used in laboratories. In addition, even when using 17.5 keV X-rays, the aperture angle can be made larger than 5 mrad, and a lens with an efficiency exceeding 40% can be realized.

[0069] [Precision test of multilayer film]

[0070] A multilayer film of each imaging mirror used in the imaging type X-ray microscope 100 was prepared. The multilayer film was manufactured by RIT (Rigaku Innovative Technologies, Inc.). As a film forming device used in the manufacture of the multilayer film, a device that achieves high film forming stability, reproducibility, and film thickness controllability by repeated calibration was used. The period length relative to the position of each obtained multilayer film was measured with high precision using X-ray reflectivity.

[0071] Figure 5 (a) and (b) are top views showing a mirror group for vertical reflection and a mirror group for horizontal reflection, respectively. Figure 5As shown in (a), the first imaging mirror 161 and the second imaging mirror 162 in the vertically reflecting imaging element 160 are formed with a multilayer film of a hyperbolic surface and an elliptical surface, respectively. Figure 5 As shown in (b), the first imaging mirror 171 and the second imaging mirror 181 in the horizontally reflecting imaging element 170 and the imaging element 180 are respectively formed with a multilayer film of an elliptical surface and a hyperbolic surface.

[0072] Figure 6 It is a graph showing the design value and the measured value of the period length of the multilayer film with respect to the position of the first imaging mirror of the vertical reflection. Figure 7 It is a graph showing the design value and measured value of the period length of the multilayer film with respect to the position of the second imaging mirror for vertical reflection. Figure 8 It is a graph showing the design value and measured value of the period length of the multilayer film with respect to the position of the first imaging mirror of horizontal reflection. Fig. 9 It is a graph showing the design value and the measured value of the period length of the multilayer film with respect to the position of the second imaging mirror of horizontal reflection.

[0073] In any figure, the straight line represents the design value of the period length corresponding to the position, and the circle represents the measured value of the period length relative to each position. The error of the period length of the multilayer film of any imaging mirror is within Within.

[0074] Fig.10 : is a graph showing the magnitude of the error in the surface shape of the second imaging mirror relative to the horizontal reflection. Fig.10 As shown, the error of the surface shape of the second imaging mirror of horizontal reflection is within 1.5nm. In addition, the surface shape of other mirrors also obtained the same result as the second imaging mirror of horizontal reflection.

[0075] [Evaluation of X-ray Image Resolution]

[0076] The imaging type X-ray microscope 100 was assembled using the mirror manufactured with the precision of the above multi-layer film. A CuKα X-ray source was used. The detailed specifications of the mirror group constituting the reflector type X-ray lens unit 150 are shown in the table below.

[0077] [Table 1]

[0078]

[0079] The high-resolution X-ray detector 190 uses a high-resolution X-ray camera Xsight XRM manufactured by Rigaku. An X-ray image of a test chart for resolution evaluation was taken as a sample. As a test chart for resolution evaluation, a thick film high-resolution type X-ray chart (XRESO-50HC, minimum size 50nm, pattern height 500nm) manufactured by NTT-AT was used. The pixel resolution of the calculated X-ray image is 12nm. In addition, the relationship between the magnification of the reflector 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.

[0080] [Table 2]

[0081]

[0082] Fig.11 (a) is a diagram showing an X-ray image of a test chart having a line width of 50 nm for evaluating resolution. Fig.11 (b) is an X-ray image showing a star pattern with a central line width of 50 nm for resolution evaluation. In any X-ray image, patterns up to 50 nm can be distinguished, and sufficient resolution is obtained for inspecting the fine structure of semiconductor devices.

[0083] Fig.12 (a) and (b) are diagrams showing an X-ray image of a 100 nm hole pattern and a portion of its 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 can be confirmed that each hole has slight differences from each other.

[0084] [Semiconductor inspection equipment]

[0085] A semiconductor inspection apparatus to which the imaging X-ray microscope 100 described above is applied will be described. Fig.13 This is a schematic diagram showing an application example in which the imaging X-ray microscope 100 is applied to a semiconductor inspection device. Fig.13 The basic structure of the imaging type X-ray microscope 100 is similar to Figure 1 The structure shown is the same. However, according to the structure corresponding to the characteristics of sample S1 or the situation unique to the inspection process, a more suitable structure can be adopted as a semiconductor inspection device. In addition, the semiconductor inspection device can be used not only for the purpose of quality inspection in the inspection process of the manufactured semiconductor, but also for the purpose of inspection in the laboratory during research and development.

[0086] The imaging X-ray microscope 100 has a high resolution of less than 100 nm, preferably less than 50 nm, and can be applied to the process of inspecting whether the fine structure of the semiconductor has defects. The imaging X-ray microscope 100 can irradiate X-rays of 15 keV or more through the X-ray source 120, so that the X-rays can be transmitted through the silicon substrate to obtain an X-ray image. In particular, from the perspective of ease of construction, it is preferred to use 17.5 keV MoKα. Thus, it is possible to observe structures buried at a depth of more than 10 μm from the surface of the semiconductor sample. In addition, since the absorption coefficient of each position can be measured by the transmittance of the X-ray, it is possible to measure the amount of material introduced into each hole by, for example, the CVD method, and quantitatively evaluate the effect of the CVD method. In addition, it is possible to directly observe structures such as the shape of the deep holes and grooves that are not visible from the surface, or the deviation of their configuration.

[0087] The sample S1 in the semiconductor inspection process is a silicon wafer formed into a flat plate (for example, 300 mm in diameter). Therefore, when performing CT scanning, it is assumed that it may be difficult to rotate 360°. In this case, it is necessary to rotate the sample S1 at a limited angle. For example, the sample S1 can be rotated within a range of ±5° or more, and the wafer sample can be tilted for measurement. In this way, structural changes that depend on depth can be observed.

[0088] It is known from experience that the size of the entire device installed at the semiconductor manufacturing and inspection site is no problem as long as it is less than 4 meters. When the imaging type X-ray microscope 100 is applied to a semiconductor inspection device, the distance on the optical axis from the sample S1 to the light receiving surface of the high-resolution X-ray detector 190 is preferably less than 3 meters. In this way, a compact semiconductor inspection device can be constructed. In addition, it can be stored in the limited storage space of the inspection room and can be easily assembled into the existing inspection process.

[0089] In addition, the aperture angle of the mirror type X-ray lens unit 150 is preferably 5 mrad or more. This can shorten the light receiving surface from the sample S1 to the high-resolution X-ray detector 190, and realize a compact semiconductor inspection device.

[0090] [Semiconductor inspection system]

[0091] Fig.14 1 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 for controlling the operation of the semiconductor inspection device 200 or as an analysis device for measuring data obtained from the semiconductor inspection device 200. Fig.14In the example shown, the semiconductor inspection system 10 is composed of a plurality of devices, but the functions of the respective devices may be integrated and configured as a single device.

[0092] (Semiconductor inspection equipment)

[0093] The semiconductor inspection device 200 includes an imaging type X-ray microscope 100, a control unit 250, and a position adjustment mechanism 270. The imaging type X-ray microscope 100 is configured as described above, and each mirror constituting the converging mirror 130 and the reflector type X-ray lens unit 150 has a reflective surface formed with a multilayer film having a high reflectivity for X-rays of a specific wavelength. Thus, even with high-energy X-rays, the numerical aperture can be increased by keeping the X-ray incident angle high, and a magnified image of sufficient intensity can be obtained in a size that can be accommodated in a laboratory. As a result, it is possible to inspect the local microstructure inside the semiconductor in a non-destructive manner.

[0094] The control unit 250 and the position adjustment mechanism 270 enable accurate alignment. The control unit 250 controls the operation of the imaging type X-ray microscope 100 according to a control instruction from the processing device 300 .

[0095] For example, the control unit 250 adjusts the relative position of the sample S1 with respect to each part in the imaging type X-ray microscope 100 through the position adjustment mechanism 270. The various parts include the X-ray irradiation unit 110, the X-ray source 120, the converging mirror 130, the aperture 135, the reflector type X-ray lens unit 150, the imaging elements 160 to 180, and the high-resolution X-ray detector 190, thereby enabling focus alignment and sample alignment. In addition, the control unit 250 can also change the voltage supplied to the X-ray irradiation unit 110 to change the X-ray intensity.

[0096] The position adjustment mechanism 270 is a mechanism that can accept automatic or operation-based control to adjust the relative position of the sample S1 with respect to the various parts of the imaging type X-ray microscope 100. Specifically, the sample adjustment mechanism, the measurement position movement (alignment), and the focus position adjustment axis implemented by the sample stage can be listed. Through this mechanism, for example, the sample position can be made close to the high-resolution X-ray detector 190 or away from the high-resolution X-ray detector 190 on the optical axis. In addition, the position adjustment mechanism 270 can rotate the rotating stage. In addition, Fig.14 The illustrated configuration is an example, and a configuration in which the operation of the imaging type X-ray microscope 100 is manually adjusted without the control unit 250 or the position adjustment mechanism 270 may be adopted.

[0097] (Processing device)

[0098] The processing device 300 controls the operation of the imaging type X-ray microscope 100 as a control device, acquires an X-ray image, and analyzes the acquired X-ray image as an analysis device. The functions of the processing device 300 are mainly realized by a computer 310 .

[0099] The computer 310 is, for example, a PC, and is composed of a processor for executing processing and a memory or hard disk for storing programs or data. The computer 310 is connected to an input device 380 such as a keyboard and a mouse and an output device 390 such as a display, receives user input from the input device 380, and outputs input screens, X-ray images, charts, and analysis results to the output device 390.

[0100] The computer 310 may also be a server device located in the cloud. In addition, from the perspective of processing load, the function of controlling the operation of the imaging type X-ray microscope 100 and the function of analyzing the measurement data may be separated, and the control may be performed by a PC installed on site, and the analysis may be performed by the server device.

[0101] 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.

[0102] 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 input of measurement conditions, for example. Examples of measurement conditions include the intensity of generated X-rays, the irradiation position of X-rays, the position of the sample, the arrangement of the detector, and the measurement time when the X-ray image is obtained. In addition, the input / output control unit 311 can output the obtained X-ray image and analysis results.

[0103] The measurement control unit 315 controls the actions for measurement by the imaging type X-ray microscope 100. The actions to be controlled include the configuration of each part, the adjustment of the relative position of the sample, and the generation of X-rays. The control instructions are sent to the control unit 250 in the semiconductor inspection device 200, thereby controlling each part of the imaging type X-ray microscope 100.

[0104] The measurement data storage unit 317 stores, as measurement data, the X-ray image acquired by the imaging type X-ray microscope 100. The stored measurement data can be used for screen display for observation of the X-ray image and analysis of the data.

[0105] The analysis unit 319 analyzes the obtained measurement data. For example, the analysis unit 319 quantitatively evaluates the surface density of the substance based on the absorption coefficient at each position. In addition, it is possible to determine whether the sample has defects based on this quantitative evaluation. In addition, the analysis unit 319 can also evaluate the depth of the hole inside the semiconductor and the state of the substance deposited by the CVD method.

[0106] (Sample)

[0107] Sample S1 has a substrate on which a semiconductor circuit is formed. In particular, the semiconductor inspection apparatus 200 is extremely effective in inspecting a semiconductor formed by extending a structure of several tens of nanometers in a direction parallel to the surface to a depth of several micrometers. In addition, when sample S1 has a semiconductor device layer provided on a substrate, the semiconductor inspection apparatus 200 is also effective in being able to measure the internal fine structure in a non-destructive manner. The semiconductor device layer can be formed of, for example, various metals or silicon compounds.

[0108] In addition, when the sample S1 is a plate-like body having a thickness of 500 μm or more, the semiconductor inspection apparatus 200 is also effective. By using the semiconductor inspection apparatus 200, a magnified image with sufficient intensity can be obtained, and inspection can be performed.

[0109] [Semiconductor inspection method]

[0110] Semiconductor inspection can be performed in a non-destructive manner using a semiconductor inspection system 10 such as that described above. In this case, the sample is first set in the sample holding portion 140. From the viewpoint of efficiency, the sample is preferably set using an automatic handling device such as a robot arm or a conveyor belt, but it can also be performed manually. In addition, the sample setting refers to fixing the semiconductor sample to the sample table, and aligning the semiconductor sample on the sample table with the X-ray irradiation, either or both. Next, the sample S1 is irradiated with X-rays of 15 keV or more. Then, the presence or absence of defects in the sample is evaluated by the resulting X-ray image. In this way, by obtaining an enlarged image of a size that can be accommodated in a laboratory and with sufficient intensity, the fine structure inside the semiconductor can be inspected for each part. In addition, the evaluation also includes the user visually evaluating the X-ray image.

[0111] [Example]

[0112] The scale of semiconductor devices with deep holes parallel to the surface is about tens to hundreds of nanometers. Fig.11 , Fig.12 The X-ray images shown in the figure actually prove that the X-ray microscope of the present invention can clearly separate structures with a line width of 50nm and 100nm holes one by one. Fig.12As shown in the result of the intensity map of (b), it can be confirmed that the individual holes have slight differences.

[0113] In addition, the present application claims priority based on Japanese Patent Application No. 2022-071044 filed on April 22, 2022, the entire contents of which are incorporated herein by reference.

[0114] Description of Reference Numerals

[0115] 10Semiconductor inspection system

[0116] 100 Imaging X-ray Microscope

[0117] 110X-ray irradiation department

[0118] 120X-ray source

[0119] 130 Converging lens

[0120] 135 aperture

[0121] 140 Sample holding unit

[0122] 150 reflector type X-ray lens unit

[0123] 160~180 imaging elements

[0124] 190 High-resolution X-ray detector (camera unit)

[0125] 200 Semiconductor inspection equipment

[0126] 250 control unit

[0127] 270 position adjustment mechanism

[0128] 300 processing devices

[0129] 310 Computer

[0130] 311 Input and output control unit

[0131] 315 Measurement Control Unit

[0132] 317 Measurement data storage unit

[0133] 319 Analysis Department

[0134] 380 Input Device

[0135] 390 Output Device

[0136] L control bus

[0137] D1~D6 distance

[0138] L1, L2 distance

[0139] S, S1 specimen

[0140] d1, d2 cycle length.

Claims

1. A semiconductor inspection device using an enlarged X-ray image, characterized in that: have: An X-ray irradiation unit is composed of a micro-focus high-output X-ray source and a focusing mirror for focusing the emitted X-rays toward a semiconductor sample for irradiation; A sample holding portion, which holds the sample; a reflector type X-ray lens section that images the X-rays transmitted through the sample; and an imaging unit for acquiring the imaged X-ray image, Each mirror constituting the condensing mirror and the reflector type X-ray lens unit has a reflective surface formed with a multilayer film having a high reflectivity for X-rays of a specific wavelength.

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

3. The semiconductor inspection device according to claim 1 or claim 2, characterized in that: The sample is a plate-like body having a thickness of 500 μm or more.

4. The semiconductor inspection device according to claim 1 or claim 2, characterized in that: The distance on the optical axis from the sample to the light receiving surface of the imaging unit is 3 m or less.

5. The semiconductor inspection device according to claim 1 or claim 2, characterized in that: The aperture angle of the reflector type X-ray lens unit is 5 mrad or more.

6. The semiconductor inspection device according to claim 1 or claim 2, characterized in that: Also available: The position adjustment mechanism can be automatically or operationally controlled to adjust the relative position of the sample with respect to each part.

7. A semiconductor inspection system, characterized in that: have: The semiconductor inspection device according to claim 1 or claim 2; and a control device connected to the semiconductor inspection device, 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 system, characterized in that: have: The semiconductor inspection device according to claim 1 or claim 2; and an analysis device connected to the semiconductor inspection device, The analyzing device quantitatively estimates the surface density of a substance at each position based on the absorption coefficient in the X-ray image acquired by the semiconductor inspection device.

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

10. The semiconductor inspection system according to claim 9, characterized in that The X-ray image is measured by tilting the sample.

11. A semiconductor inspection method, which is a semiconductor inspection method performed in a non-destructive manner using the semiconductor inspection apparatus according to claim 1 or claim 2, characterized in that: Include: The step of placing the sample in the sample holding portion; irradiating the sample with X-rays of 15 keV or more; and The step of evaluating the presence or absence of defects in the sample by using the imaged X-ray image.

Images