Sample measuring device

Abstract

This invention provides a sample measuring device that can efficiently measure the fine structure and optical properties of a target sample's surface while changing the angle of incidence or reflection of light. [Solution] The sample measuring device A1 includes a light source unit 4, a non-polarizing beam splitter 5, an intensity conversion element 3, an objective lens 2, a target sample 1, and an image sensor 6. Furthermore, a Fourier plane 100 is located on the opposite side of the target sample 1 from the objective lens 2, at a distance of focal length f, and the intensity conversion element 3 is positioned on the Fourier plane 100. The intensity conversion element 3 is composed of a liquid crystal element having multiple compartments, and the transmittance of light passing through each compartment can be controlled by electrical control.

Description

Technical Field

[0001] The present invention relates to a sample measuring device.

Background Art

[0002] Conventionally, various sample measuring devices have been used to irradiate a target sample with light and detect the light reflected from the target sample with a detector to observe the target sample.

[0003] In such a sample measuring device, as a method for observing the three-dimensional shape or the like of the surface of a target sample, for example, dark-field observation using a metal microscope or the like is available.

[0004] This dark-field observation using a metal microscope or the like is a method of observing the surface shape by irradiating the target sample with incident light from outside the lens field of view and imaging using the light that has entered the lens field of view among the light scattered on the sample surface (see, for example, Non-Patent Document 1).

[0005] Also, in an optical microscope, an apodization filter having a high transmittance at the center and a decreasing transmittance toward the periphery is disposed at the pupil position of the objective lens, and the shape of the light intensity distribution is corrected and the resolution is improved by continuously changing the intensity distribution of the light passing through the filter (see, for example, Patent Document 1).

[0006] Furthermore, an ellipsometer, which is a sample measuring device that measures optical physical properties such as refractive index based on given film thickness information for a thin film on the surface of a target sample using light, is used.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Non-Patent Documents

[0008] [Non-Patent Document 1] Evident Scientific website, Learning Center, "What is reflected dark-field observation?", [Accessed July 23, 2025], Internet<URL:https: / / evidentscientific.com / ja / learn / microscope / terms / feature14> [Overview of the project] [Problems that the invention aims to solve]

[0009] In dark-field observation using the aforementioned metallurgical microscope, significant scattering is unlikely to occur in response to smooth changes or inclinations on the sample surface, and most of the scattered light cannot be captured within the lens's field of view. Therefore, smooth changes or inclinations on the sample surface cannot be detected, making it an insufficient method for observing the fine shape of the sample surface in order to observe its details.

[0010] Furthermore, while optical microscopes equipped with apodization filters can improve resolution, they do not possess the functionality to specifically impart sensitivity to fine textures such as minute steps or inclinations on the surface of the target sample. Therefore, they were unsuitable for acquiring information about the fine shape of the sample surface.

[0011] Furthermore, dark-field observation using a metallurgical microscope and observation using an optical microscope equipped with an apodization filter are methods for imaging the target sample, not methods for measuring the optical properties of the target sample.

[0012] On the other hand, an ellipsometer is a device that measures only the optical properties of a sample and is not a method for observing the shape of the sample surface.

[0013] Thus, among conventional sample measuring devices, there was no device that could perform both surface shape observation and optical property measurement with a single device. Furthermore, there was room for improvement in the technology for acquiring information on the fine shape of the surface during surface shape observation.

[0014] Furthermore, with the conventional sample measuring devices described above, it was difficult to observe the target sample while selecting an arbitrary angle for the angle of incidence of light incident on the sample surface (hereinafter referred to as "incident light") or the angle of reflection of light reflected from the sample surface (hereinafter referred to as "reflected light") without mechanical operation.

[0015] In other words, for example, even with the same sample, the reflection intensity of the reflected light from the sample surface changes depending on the angle of incidence of the light incident on the sample surface. Therefore, in order to observe the surface of the sample more accurately, it was necessary to mechanically manipulate and change the angle of incidence or reflection of the light and obtain observation information that reflects each angle.

[0016] Furthermore, when attempting to measure the optical anisotropy of a sample, it was necessary to mechanically manipulate the azimuth angle in addition to the angle of incidence or reflection of light to obtain observational information; otherwise, the optical properties could not be determined.

[0017] The present invention was conceived in view of the above points, and aims to provide a sample measuring device that can perform both shape observation of the sample surface, including information on the fine shape of the sample surface, and measurement of optical properties with a single device, and that can obtain observation information while selecting any angle for the angle of incidence, reflection, or azimuth of light. [Means for solving the problem]

[0018] To achieve the above objective, the sample measuring apparatus of the present invention comprises a light source, a detector that receives at least a portion of the light from the light source that has been reflected from the target sample and passed through the objective lens, and an intensity conversion element that is arranged on at least one of the Fourier plane of the objective lens or a plane optically equivalent to the Fourier plane, and has a plurality of compartments that can individually control the intensity of the transmitted light.

[0019] Here, the detector receives at least a portion of the light from the light source that has been reflected from the target sample and passed through the objective lens, thereby acquiring image information of the sample surface of the target sample.

[0020] Furthermore, by having an intensity conversion element positioned on at least one of the Fourier planes of the objective lens or a plane optically equivalent to the Fourier plane, and having multiple compartments whose transmitted light intensity can be individually controlled, the optical path of the light can be controlled in a manner that reflects the incident or reflection angle, by utilizing the characteristic that there is a correspondence between the position through which light is transmitted on the Fourier plane (or on an optically equivalent plane) and the incident or reflection angle of light onto the target sample. In other words, by controlling the intensity conversion element so that light with one incident angle (or reflection angle) is transmitted through a compartment among the multiple compartments, it becomes possible to incident light with a specific incident angle onto the target sample or to detect light with a specific reflection angle with the detector. As a result, it becomes possible to obtain image information of the sample surface for light with a specific incident or reflection angle, which could not be observed when multiple lights with different incident or reflection angles were mixed. In addition, it becomes possible to observe images of fine texture changes, including the tilt and steps of the sample surface. Furthermore, the phrase "a section through which light with a single incident angle (or reflection angle) passes" used here does not strictly limit itself to light at a specific angle, as each section has a certain range. It includes light at angles immediately before and after that specific angle, thus encompassing a certain degree of flexibility. The same definition applies to the same notation described later.

[0021] Furthermore, when a thin film structure exists on the sample surface, by changing the section through which the light of the intensity conversion element passes (selecting an arbitrary incident angle or reflection angle) and acquiring imaging images for each section, it is possible to obtain a light vibration pattern that reflects the detected light intensity (reflection intensity) corresponding to the change in the incident angle (or reflection angle) of the light. And this light vibration pattern, for example, for a single-layer thin film, for each angle, the detected light intensity resulting from the interference between the light reflected from the surface of the thin film and the light reflected from the deepest part of the thin film can be obtained. Therefore, by analyzing the light vibration pattern, the values of the film thickness and optical constants of the thin film structure can be determined. Also, on the same sample surface, when thin films with different film thicknesses exist, it is possible to determine the values of the film thickness and optical constants for each region of the film thickness.

[0022] Note that the property that the position where the light on the Fourier plane (or an optically equivalent plane) passes and the incident angle of the light to the target sample or the reflection angle of the light are in a corresponding relationship means that for light with the same incident angle (reflection angle) to the target sample, even if the light hitting the sample surface is different, the light passes through the same position on the Fourier plane. Also, the section through which the light having one incident angle (or reflection angle) passes in the intensity conversion element here includes not only the mode of providing one section but also the mode of providing a plurality of sections.

[0023] In addition, the intensity conversion element is arranged on the Fourier plane. When the light before entering the target sample and the light reflected from the target sample can pass through the intensity conversion element, it is possible to make the light with the set incident angle enter the sample, and at the same time, it is possible to detect the light with the set reflection angle with a detector. That is, on the Fourier plane of the objective lens, both the incident light to the sample and the reflected light from the sample pass through. Therefore, by arranging the intensity conversion element at that position and making the light pass through the section through which the light with a specific incident angle and the light with a specific reflection angle pass, the intensity of the transmitted light can be controlled. Here, a part of the reflected light that can pass through the section also passes through the section through which the light with a specific incident angle passes. Also, a part of the incident light that can pass through the section also passes through the section through which the light with a specific reflection angle passes.

[0024] Also, based on the optical axis of the objective lens, by controlling the intensity conversion element so that light can pass through the section where incident light and reflected light with an axially symmetric optical path pass through, for light at a specific angle where the incident angle and the reflection angle are the same, the light that is specularly reflected by the sample can be extracted, and imaging image information can be obtained. Also, it becomes possible to perform image observation of the optical physical properties of the sample and measurement of optical physical property values (for example, reflectance, optical constants).

[0025] Also, based on the optical axis of the objective lens, by controlling the intensity conversion element so that light can pass through the section where incident light and reflected light with a non-axially symmetric optical path pass through, for incident light at a certain incident angle, the light scattered on the surface of the target sample can be detected by the detector. That is, by detecting the light scattered due to minute inclinations, steps, etc. on the surface of the target sample, it becomes possible to perform image observation of fine texture changes.

[0026] Also, the intensity conversion element is arranged on an equivalent plane transferred to the light source side, and when light before entering the target sample passes through the intensity conversion element, light at the set incident angle can be made to enter the sample. That is, on the plane optically equivalent to the Fourier plane of the objective lens transferred to the light source side, since the incident light to the sample passes through, by arranging the intensity conversion element at that position, for the section where light at a specific incident angle passes through, the intensity of the transmitted light can be controlled so that light can pass through.

[0027] Also, when the surface of the target sample is an ideal flat plane, for incident light at a certain incident angle, the light specularly reflected by the sample can be detected by the detector, and imaging image information can be obtained. Also, it becomes possible to perform image observation of the optical physical properties of the sample and measurement of optical physical property values (for example, reflectance, optical constants).

[0028] Furthermore, when a thin film structure exists on the surface of the target sample, by changing the section through which light is transmitted by the intensity conversion element—that is, by arbitrarily selecting the incident angle of the incident light—and acquiring images in each section, it is possible to obtain a light vibration pattern that reflects the detected light intensity (reflected intensity) corresponding to the change in the incident angle of the light. By analyzing this light vibration pattern, the film thickness and optical constants of the thin film structure can be determined. Moreover, even when thin films with different thicknesses exist on the same sample surface, it is possible to determine the film thickness and optical constants for each region of film thickness.

[0029] Furthermore, the intensity conversion element is positioned on an equivalent surface transferred to the detector side, and when light reflected from the target sample passes through the intensity conversion element, the detector can detect light at a set reflection angle. In other words, since reflected light from the sample passes through the surface that is optically equivalent to the Fourier plane of the objective lens transferred to the detector side, the intensity conversion element can be positioned at that location to control the intensity of the transmitted light so that light at a specific reflection angle passes through the area.

[0030] Furthermore, when the surface of the target sample is an ideal plane, the reflected light has a constant reflection angle, and the light specularly reflected by the sample can be detected by the detector to obtain image information. In addition, it becomes possible to observe the optical properties of the sample visually and measure optical property values ​​(e.g., reflectance, optical constants).

[0031] Furthermore, when a thin film structure exists on the surface of the target sample, by changing the section through which the light transmitted by the intensity conversion element is altered—that is, by arbitrarily selecting the reflection angle of the reflected light—and acquiring images in each section, it is possible to obtain a light vibration pattern that reflects the detected light intensity (reflection intensity) corresponding to the change in the reflection angle of the light. By analyzing this light vibration pattern, the film thickness and optical constants of the thin film structure can be determined. Moreover, even when thin films with different thicknesses exist on the same sample surface, it is possible to determine the film thickness and optical constants for each region of film thickness.

[0032] Furthermore, if the intensity conversion element is positioned on an equivalent surface transferred to the light source side, and light before it enters the target sample passes through this intensity conversion element, and if the intensity conversion element is also positioned on an equivalent surface transferred to the detector side, and light reflected from the target sample passes through the intensity conversion element on the detector side, then by using two intensity conversion elements positioned at different locations, it is possible to cause light at a set incidence angle to enter the sample, and simultaneously, the detector can detect light at a set reflection angle. In other words, on the equivalent surface transferred to the light source side, the light incident on the sample passes through, and on the equivalent surface transferred to the detector side, both the incident light and the reflected light from the sample pass through. Therefore, by positioning intensity conversion elements at each location, the intensity of the transmitted light can be controlled so that light passes through sections where light at a specific incidence angle and light at a specific reflection angle are transmitted.

[0033] Furthermore, by controlling the intensity conversion element so that light passes through the sections where incident and reflected light, whose optical paths are axially symmetrical with respect to the optical axis of the objective lens, are transmitted, it is possible to extract the specularly reflected light from the sample for light at a specific angle where the incident angle and reflection angle are the same, and acquire image information. In addition, it becomes possible to observe the optical properties of the sample in images and measure optical property values ​​(e.g., reflectance, optical constants).

[0034] Furthermore, by controlling the intensity conversion element so that light passes through a region where incident and reflected light, whose optical paths are not axially symmetrical, are transmitted with respect to the optical axis of the objective lens, it is possible to detect light scattered at the surface of the target sample for incident light at a certain incident angle. In other words, by detecting light scattered due to minute inclinations or steps on the surface of the target sample, it becomes possible to observe images of minute texture changes.

[0035] Furthermore, by controlling the intensity conversion elements on both the light source side and the detector side to detect light at a specific incident angle or a specific reflection angle, dark-field observation can be performed using only diffracted light of a specific order. That is, for a sample on which diffracted light is generated at the surface of the target sample, observation using 0th-order diffracted light is possible by detecting light at the same incident and reflection angles. Also, when light with a strong reflection intensity is obtained at a reflection angle different from a certain incident angle, it is possible to detect the reflected light at that different reflection angle and perform dark-field observation using only diffracted light of a specific order, for example, 1st-order diffracted light. In addition, since diffracted light periodically produces light with a strong reflection intensity, it is possible to detect not only 1st-order diffracted light but also strong light at other reflection angles and perform dark-field observation using only diffracted light of a specific order, such as 2nd-order or 3rd-order diffracted light.

[0036] Furthermore, when the intensity conversion element is placed on the Fourier plane, and both light before it enters the target sample and light reflected from the target sample pass through it, and when the intensity conversion element is placed on an equivalent plane transferred to the light source side, and light before it enters the target sample passes through the intensity conversion element on the light source side, it is possible to use two intensity conversion elements placed at different positions to cause light at a set incidence angle to enter the sample, and at the same time, it is possible to detect light at a set reflection angle with a detector. In other words, on the equivalent plane transferred to the light source side, the incident light to the sample passes through, and on the Fourier plane, both the incident light to the sample and light reflected from the sample pass through. Therefore, by placing intensity conversion elements at each position, the intensity of the transmitted light can be controlled so that light passes through sections where light at a specific incidence angle and light at a specific reflection angle passes through.

[0037] Furthermore, by controlling the intensity conversion element so that only the sections through which incident and reflected light, whose optical paths are axially symmetrical with respect to the optical axis of the objective lens, are transmitted, it is possible to extract the specularly reflected light from the sample for light at a specific angle where the incident angle and reflection angle are the same, and acquire image information. In addition, it becomes possible to observe the optical properties of the sample in images and measure optical property values ​​(e.g., reflectance, optical constants).

[0038] Furthermore, by controlling the intensity conversion element so that light passes through a region where incident and reflected light, whose optical paths are not axially symmetrical, are transmitted with respect to the optical axis of the objective lens, it is possible to detect light scattered at the surface of the target sample for incident light at a certain incident angle. In other words, by detecting light scattered due to minute inclinations or steps on the surface of the target sample, it becomes possible to observe images of minute texture changes.

[0039] Furthermore, by controlling the intensity conversion elements on both the light source side and the detector side to detect light at a specific incident angle or a specific reflection angle, dark-field observation can be performed using only diffracted light of a specific order. That is, for a sample on which diffracted light is generated at the surface of the target sample, observation using 0th-order diffracted light is possible by detecting light at the same incident and reflection angles. Also, when light with a strong reflection intensity is obtained at a reflection angle different from a certain incident angle, it is possible to detect the reflected light at that different reflection angle and perform dark-field observation using only diffracted light of a specific order, for example, 1st-order diffracted light. In addition, since diffracted light periodically produces light with a strong reflection intensity, it is possible to detect not only 1st-order diffracted light but also strong light at other reflection angles and perform dark-field observation using only diffracted light of a specific order, such as 2nd-order or 3rd-order diffracted light.

[0040] Furthermore, if the detector is configured to measure polarization, it becomes possible to detect information about the polarization state of light. [Effects of the Invention]

[0041] The sample measuring device according to the present invention is capable of performing both shape observation of the sample surface, including information on the fine shape of the sample surface, and measurement of optical properties with a single device, and can provide a sample measuring device that can obtain observation information while selecting any angle for the angle of incidence, reflection, or azimuth of light. [Brief explanation of the drawing]

[0042] [Figure 1]This is a schematic diagram illustrating the properties of the Fourier surface. [Figure 2] This is a schematic diagram illustrating the properties of the Fourier surface. [Figure 3] This is a schematic diagram showing the overall configuration of the first embodiment of the present invention. [Figure 4] This is a schematic diagram showing the overall configuration of the first embodiment of the present invention. [Figure 5] This is a schematic diagram showing the overall configuration of a second embodiment of the present invention. [Figure 6] This is a schematic diagram showing the light interference that occurs in a target sample having a thin film structure on its surface. [Figure 7] This is a schematic diagram showing the overall configuration of the third embodiment of the present invention. [Figure 8] This is a schematic diagram showing the overall configuration of a fourth embodiment of the present invention. [Figure 9] This is a schematic diagram showing the overall configuration of a fourth embodiment of the present invention. [Figure 10] This is a schematic diagram showing the light interference that occurs in a target sample having a periodic structure on its surface. [Figure 11] This is a schematic diagram showing the overall configuration of the fifth embodiment of the present invention. [Figure 12] This is a schematic diagram showing the overall configuration of the fifth embodiment of the present invention. [Figure 13] This is a schematic diagram showing an example of the intensity distribution pattern of an intensity conversion element. [Figure 14] This is a schematic diagram showing an example of the intensity distribution pattern of an intensity conversion element. [Modes for carrying out the invention]

[0043] Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as "embodiments") will be described with reference to the drawings. The following description is an example of a sample measuring device to which the present invention is applied, and the present invention is not limited thereto; the design can be modified as appropriate.

[0044] First, the characteristics of the Fourier plane or a plane optically equivalent to the Fourier plane, which are related to the function of the present invention, will be explained with reference to the drawings.

[0045] Figures 1(a) and 1(b) show an objective lens 2 positioned in front of the target sample 1, and a Fourier plane 100 formed at a distance of focal length f on the opposite side of the target sample 1 from the objective lens 2. The Fourier plane 100 is an optical surface that forms an inverse space image of the target sample 1 relative to its real space image.

[0046] Figures 1(a) and 1(b) show a part of a configuration in which light from a light source (not shown) is shone onto the target sample 1 through the objective lens 2, the light reflected from the target sample 1 passes through the objective lens 2 again, and the light is detected by a detector (not shown).

[0047] Furthermore, the Fourier surface, or a surface optically equivalent to the Fourier surface described later, is a term that refers to an optical surface, and in the drawings illustrating each embodiment of the present invention, it is shown as a dotted line composed of multiple rectangles.

[0048] Here, the Fourier plane 100 is not necessarily limited to being formed at a distance of focal length f on the opposite side of the target sample 1 with respect to the objective lens 2, but may also be formed at a distance different from the focal length f depending on the conditions.

[0049] This Fourier plane 100 has the characteristic that if the angle of incidence of the incident light passing through the objective lens 2 and into the target sample 1 is different, the light passes through different positions on the Fourier plane 100, and if the angle of incidence of the incident light is the same, it passes through the same position on the Fourier plane 100 (see Figure 1(a)).

[0050] Furthermore, the Fourier plane 100 has the characteristic that when reflected light reflected from the target sample 1 passes through the objective lens 2 and then through the Fourier plane 100, if the reflection angles of the reflected light are different, it passes through different positions on the Fourier plane 100, and if the reflection angles of the reflected light are the same, it passes through the same position on the Fourier plane 100 (see Figure 1(a)).

[0051] For example, as shown in Figure 1(a), incident light with different incident angles θ1, θ2, and θ3 passes through different positions X1, X2, and X3 on the Fourier plane 100.

[0052] Furthermore, as shown in Figure 1(a), the reflected light with different reflection angles, -θ1, -θ2, and -θ3, passes through different positions on the Fourier surface 100, namely positions -X1, -X2, and -X3.

[0053] Furthermore, positions X1 and -X1 on the Fourier plane 100 through which light incident and reflected at the same angle, such as the incident angle θ1 and the reflection angle -θ1, are symmetrical with respect to the center of the objective lens 2 as the origin.

[0054] Furthermore, as shown in Figure 1(b), for example, multiple incident light beams incident on the target sample 1 at the same incident angle θ will pass through the same position X on the Fourier plane 100 before incident on the target sample 1, even if the irradiation positions of the light on the surface of the target sample 1 are different.

[0055] Furthermore, multiple reflected light beams from the target sample 1 at the same reflection angle -θ will, even if they are reflected at different positions on the surface of the target sample 1, pass through the objective lens 2 and then pass over the Fourier plane 100, all passing through the same position -X on the Fourier plane 100.

[0056] Furthermore, the characteristics of the Fourier plane 100 described in Figures 1(a) and 1(b) are the same for optically equivalent planes (hereinafter referred to as "equivalent planes" as needed) that are transmitted by optical elements such as relay lenses. That is, there is a one-to-one correspondence between the angle of incidence or reflection of light and the position through which the light passes on the equivalent plane.

[0057] Furthermore, the present invention is characterized by utilizing the properties of the Fourier surface 100 (or an equivalent surface) to arrange an intensity conversion element 3 on the Fourier surface 100 and controlling the path of light (optical path) that passes through a position on the Fourier surface 100 corresponding to the incident angle of the incident light or the reflection angle of the reflected light (see Figure 1).

[0058] Here, the intensity conversion element 3 is composed of, for example, a liquid crystal element having multiple compartments, and the transmittance of light passing through each compartment can be continuously controlled by electrical control. Furthermore, the multiple compartments have a shape that is, for example, planar and arranged in a grid.

[0059] Furthermore, as a mechanism for controlling the light transmittance in multiple sections of the intensity conversion element 3, a structure can be adopted that controls the absorption or scattering of light passing through each section to control the light transmittance. In this embodiment, it becomes possible to control the light transmittance regardless of the polarization state of the light.

[0060] This allows for the control of not only concentric intensity distributions that function similarly to conventional aperture mechanisms and ring illumination, but also, for example, asymmetrical intensity distributions and intensity distributions with multiple transmission regions.

[0061] For example, in areas where light is to be transmitted, the light absorption rate in those areas can be lowered to allow light to pass through, while in areas where light is not to be transmitted, the light absorption rate in those areas can be increased to block light. Alternatively, instead of controlling the light absorption rate, a method of controlling the light scattering intensity can also be employed.

[0062] Furthermore, as another mechanism for controlling the light transmittance in multiple sections of the intensity conversion element 3, a structure can be used that controls the light transmittance by allowing only light with a specific polarization direction to pass through.

[0063] In this embodiment, for example, by combining a polarizer having a certain linear direction with an optical element capable of selecting the polarization direction of light, the polarization direction of light passing through a section can be adjusted to a specific direction, thereby controlling the transmission of light.

[0064] Furthermore, as another example of the elements constituting the intensity conversion element 3, it is also possible to use reflective elements that control the reflection intensity of light for each section, or reflective elements that reflect light of a specific polarization. The fact that reflective elements can be used in the intensity conversion element 3 is also true in each embodiment of the present invention described below.

[0065] Such intensity conversion elements 3, which can control the transmittance of light in multiple sections, are arranged on the Fourier plane 100. By aligning the individual sections of the intensity conversion elements 3 with positions on the Fourier plane 100 corresponding to the incident angle of the incident light or the reflection angle of the reflected light, it becomes possible to control the light for each optical path by allowing only light at a specific angle to pass through or blocking only light at a specific angle for each incident angle or reflection angle.

[0066] According to this, it becomes possible to control the optical path for each incident angle or reflection angle of light passing through the Fourier plane 100, so that light with a specific incident angle is incident on the target sample, or light with a specific reflection angle is extracted and guided to the detector.

[0067] Furthermore, by placing the intensity conversion element 3 on an equivalent plane instead of the Fourier plane 100, it becomes possible to control the optical path for each incident angle or reflection angle, just as when it is placed on the Fourier plane 100.

[0068] For example, as shown in Figure 1(a), if the light is controlled to be passable only in the section 320 at position X2 where incident light with incident angle θ2 passes through the Fourier plane 100, and in the section 321 at position -X2 where reflected light with reflection angle θ2 passes through the Fourier plane 100, the intensity conversion element 3 can transmit only the incident light with incident angle θ2 and the reflected light with reflection angle -θ2, while blocking the optical paths of incident or reflected light at other angles.

[0069] Furthermore, as shown in Figure 2(a), if the light is controlled to be passable only in the section 320 at position X2 where incident light with incident angle θ2 passes through the Fourier plane 100, and in the section 311 at position -X1 where reflected light with reflection angle -θ1 passes through the Fourier plane 100, the intensity conversion element 3 can transmit only the incident light with incident angle θ2 and the reflected light with reflection angle -θ1, while blocking the optical paths of incident or reflected light at other angles.

[0070] In other words, by using the intensity conversion element 3, the optical path can be controlled to extract reflected light with a reflection angle that is different from the incident angle of the incident light.

[0071] Furthermore, in the case of extracting reflected light with a different reflection angle than the incident angle (θ), the reflection angle is not limited to the aforementioned reflection angle -θ2, but any reflection angle -(θ+Δθ) can be set, and the reflected light can be transmitted through the section at position -(X+ΔX) corresponding to that reflection angle and detected by the detector (see Figure 2(b)).

[0072] Next, a specific embodiment of the present invention using the Fourier surface 100 (or equivalent surface) and the intensity conversion element 3 described above will be explained.

[0073] [First Embodiment of the Present Invention] Figure 3 shows a sample measuring device A1, which is a first embodiment of the present invention.

[0074] This sample measuring device A1 is characterized in that, similar to the structure shown in Figures 1 and 2 above, it has an objective lens 2 positioned in front of the target sample 1, and a Fourier plane 100 located on the opposite side of the target sample 1 from the objective lens 2, at a distance of focal length f, with an intensity conversion element 3 positioned on the Fourier plane 100.

[0075] In the sample measuring device A1, the intensity conversion element 3, positioned on the Fourier plane 100, allows for the simultaneous control of the optical paths of both the incident light incident on the target sample 1 and the reflected light reflected from the surface of the target sample 1 using a single intensity conversion element 3.

[0076] Here, the focal length f in the sample measuring device A1 is not particularly limited and can be set as appropriate. Furthermore, as mentioned above, the Fourier plane 100 is not necessarily limited to being formed at a distance of focal length f on the opposite side of the target sample 1 with respect to the objective lens 2, and under certain conditions, it may also be formed at a distance different from the focal length f. These details are also true in other embodiments of the present invention described later.

[0077] Furthermore, Figure 3 shows an example of controlling light where the angle of incidence and the angle of reflection are the same, and the optical paths of the incident and reflected light are axially symmetric with respect to the optical axis of objective lens 2 (combinations of incident ray L1 and reflected ray L2, and incident ray L3 and reflected ray L4). In addition, the combination of incident ray L1 and incident ray L3, and the combination of reflected ray L2 and reflected ray L4, are also examples of light whose optical paths are axially symmetric with respect to the optical axis of objective lens 2.

[0078] Furthermore, in Figure 3, for the sake of clarity, the indicative representation of the incident ray L3 and reflected ray L4 in the range between objective lens 2 and target sample 1 has been omitted. Also, in Figure 3, the luminous beam irradiated onto a single point on the target sample 1 is schematically shown with the symbol LF.

[0079] As shown in Figure 3, the sample measuring device A1 includes a light source unit 4, a non-polarizing beam splitter 5, an intensity conversion element 3, an objective lens 2, a target sample 1, and an image sensor 6.

[0080] Here, the light source unit 4 is a component that emits light to irradiate the target sample 1, and is composed of a single light-emitting element or a combination of a light-emitting element and an optical element (such as a polarizer) that selects the polarization direction of the light. Furthermore, an LED light source can be used as the light-emitting element.

[0081] Furthermore, the non-polarized beam splitter 5 is an optical element that guides a portion of the light emitted from the light source unit 4 to the target sample 1. The non-polarized beam splitter 5 is also a component that guides a portion of the reflected light reflected from the surface of the target sample 1 to the image sensor 6.

[0082] Furthermore, the unpolarized beam splitter 5 is an optical element that splits the incident light at a constant rate while maintaining the polarization state of the incident light. That is, for example, when light incident on the unpolarized beam splitter 5, a portion is reflected toward the target sample 1, and the remaining portion passes through the unpolarized beam splitter 5 and is split at a constant rate.

[0083] Furthermore, as described above, the intensity conversion element 3 is composed of a liquid crystal element having multiple compartments, and the transmittance of light passing through each compartment can be controlled by electrical control.

[0084] Furthermore, the intensity conversion element 3 can control the transmittance of light passing through each of the multiple sections in a manner corresponding to the incident angle of light incident on the target sample 1 or the reflection angle of light reflected from the surface of the target sample 1.

[0085] Furthermore, the objective lens 2 is a lens component that focuses the light that passes through the intensity conversion element 3 and is directed toward the target sample 1. The objective lens 2 is also a lens component that focuses the reflected light reflected by the target sample 1 and directs it toward the image sensor 6.

[0086] Furthermore, objective lens 2 also forms the Fourier plane 100, which forms the inverse spatial image of the target sample 1 relative to the real spatial image. The Fourier plane 100 is formed at a distance of focal length f on the opposite side of the target sample 1 from objective lens 2 (see Figure 3).

[0087] Furthermore, the image sensor 6 is a camera component that receives reflected light from the light source unit 4, which is reflected by the target sample 1, and acquires image information of the surface of the target sample.

[0088] Based on the light information received by the image sensor 6, it becomes possible to observe the optical properties of the sample as images and measure optical property values ​​(e.g., reflectance, optical constants). Furthermore, if a thin film structure exists on the sample surface, the thickness of that thin film can also be measured.

[0089] Furthermore, in another configuration of the sample measuring device A1, a polarizing camera can be used as the detector instead of the image sensor 6. Detection using a polarizing camera will be described later.

[0090] Furthermore, the sample measuring device A1 is provided with lenses 70 and 71 that guide the light from the light source unit 4 to the unpolarized beam splitter 5. In addition, lenses 72, 73, and 74 are provided that guide the light that has passed through the unpolarized beam splitter 5 to the image sensor 6.

[0091] Furthermore, the combination of lens 70 and lens 71, or the combination of lens 72 and lens 73, functions as a relay lens that transfers an optically equivalent surface to the Fourier plane 100 to another location in other embodiments of the present invention described later.

[0092] Here, it is not necessarily required that the unpolarized beam splitter 5 be used in the sample measurement device A1; any optical element capable of splitting light at a certain ratio can be used.

[0093] Next, we will explain the measurement using the sample measuring device A1. The intensity conversion element 3 of the sample measuring device A1 shown in Figure 3 controls the transmittance so that light is transmitted to a section corresponding to the angle of incidence of the incident light ray L1 onto the target sample 1, and to a section corresponding to the angle of reflection of the reflected light ray L2 from the target sample 1.

[0094] In other words, the intensity conversion element 3 transmits an incident light ray L1 at a specific incident angle and irradiates the target sample 1 with it, and transmits a reflected light ray L2 at the same angle of reflection that can be detected by the image sensor 6.

[0095] Furthermore, since incident light rays L1 and L3 are axially symmetrical in their optical paths around the optical axis of objective lens 2, incident light ray L3 passes through the same section as reflected light ray L2 of intensity conversion element 3, and reflected light ray L4 passes through the same section as incident light ray L1.

[0096] As a result, the image sensor 6 can detect the reflected light L2 (or reflected light L4) that is specularly reflected by the incident light ray L1 (or incident light ray L3) at the surface of the target sample 1, and detect the light that is specularly reflected at a given angle of incidence. It can also determine the reflectance of the specularly reflected light.

[0097] Furthermore, the reflected light ray L5 (or L6) that is scattered by the surface of the target sample 1 from the incident light ray L1 (or L3) attempts to pass through a different position on the Fourier plane 100 than the position through which the reflected light ray L2 passes. As a result, it is blocked by a section of the intensity conversion element 3 that cannot transmit light, and is not detected by the image sensor 6.

[0098] Furthermore, by changing the section of the intensity conversion element 3 that transmits light according to the incident light at different incident angles, it is possible to detect light that is specularly reflected at different incident angles.

[0099] According to this, by changing the light-transmitting section within each section of the intensity conversion element 3, it becomes possible to select any angle for the incident angle of light on the surface of the target sample, and to acquire and observe images of the sample surface when light with each incident angle is specularly reflected at the sample surface. In other words, it is possible to observe images with different reflectances (different light intensities) for each incident angle.

[0100] Here, by using a polarization camera instead of the image sensor 6 as a detector, it becomes possible to detect changes in the polarization state of light occurring on the surface of the target sample 1.

[0101] In other words, when interaction with light occurs on the surface of the target sample 1 and the polarization state of the light changes, the polarization state of the light that has changed on the sample surface can be detected by the polarization camera for both the polarization horizontal to the incident surface and the polarization perpendicular to the incident surface of the incident light from the light source unit 4.

[0102] Furthermore, regarding the reflectivity of light in sample 1, the reflectivity of polarized light horizontal to the incident surface and polarized light perpendicular to the incident surface changes depending on the angle of incidence.

[0103] Therefore, by detecting light with a polarizing camera, it is possible to detect the reflectance for different incident angles (reflectance of polarization horizontal to the incident surface and reflectance of polarization perpendicular to the incident surface) by separating the polarization horizontal to the incident surface and the polarization perpendicular to the incident surface.

[0104] In this invention, a polarization camera is not necessarily required as the detector; any measuring means capable of measuring polarization can be used as appropriate. For example, a conventional visible light camera (such as an image sensor) may be combined with a polarizer that controls the polarization direction to a specific direction to measure polarization.

[0105] Furthermore, the polarization measured by the polarization camera may not only detect polarization components in two directions (linear polarization component horizontal to the plane of incidence and linear polarization component perpendicular to the plane of incidence), but may also be configured to detect polarization components in four directions (linear polarization component horizontal to the plane of incidence, linear polarization component perpendicular to the plane of incidence, 45° linear polarization component, and 135° linear polarization component) by combining the polarization camera and polarizer.

[0106] Furthermore, if the polarization components in four directions are detected, it is possible to calculate the Stokes parameter, which is a physical quantity representing the physical properties of polarization, by obtaining information on the change in the linear polarization components in four directions with and without the polarizer.

[0107] Furthermore, in each embodiment of the present invention described later, the same effect can be obtained by employing a polarizing camera or a measuring means capable of measuring polarization as the detector.

[0108] Next, a measurement using sample measuring device A2, in which the intensity conversion element 3 is arranged on the Fourier plane 100, similar to sample measuring device A1, will be described with reference to Figure 4. The measurement using sample measuring device A2 is a modification of the first embodiment of the present invention.

[0109] In the following explanation, components having the same function as those described for the sample measuring device A1 will be given the same reference numerals, and detailed explanations will be omitted.

[0110] Figure 4 shows the sample measuring device A2. The intensity conversion element 3 of the sample measuring device A2 controls the transmittance so that light is transmitted in a section corresponding to the angle of incidence of the incident light ray L1 onto the target sample 1, and in a section corresponding to the reflection angle of the reflected light ray L5 scattered from the surface of the target sample 1 by the incident light ray L1.

[0111] In other words, the difference from the sample measuring device A1 described above is that, among the multiple compartments of the intensity conversion element 3, light is transmitted to the compartment through which light scattered at the sample surface (reflected light L5) passes, rather than light specularly reflected by the target sample 1 (reflected light L2) with respect to the incident light L1.

[0112] The intensity conversion element 3 of this sample measuring device A2 transmits an incident light ray L1 at a specific incident angle and irradiates the target sample 1 with it. This then transmits the reflected light ray L5 of the diffuse reflection scattered from the surface of the target sample 1, which can then be detected by the image sensor 6.

[0113] Furthermore, as shown in Figure 4, the incident light ray L7, which passes through the section of the intensity conversion element 3 through which the reflected light ray L5 is transmitted, is incident on the target sample 1. This incident light ray L7 has an incident angle that is the same as the reflection angle of the reflected light ray L5.

[0114] Furthermore, as shown in Figure 4, among the multiple compartments of the intensity conversion element 3, the reflected light ray L8 that passes through the compartment through which the incident light ray L1 is transmitted is detected by the image sensor 6. This reflected light ray L8 has a reflection angle that is the same as the incident angle of the incident light ray L1. Also, the reflected light ray L8 is the light that was scattered from the sample surface by the incident light ray L7.

[0115] In this way, the sample measuring device A2 extracts the reflected light L5, which is scattered from the sample surface by the incident light L1, and the reflected light L8, which is scattered from the sample surface by the incident light L7, using the intensity conversion element 3, and detects them with the image sensor 6 to acquire image information.

[0116] The light scattered from the surface of this sample is caused by minute inclines or steps on the sample surface, and the sample measurement device A2 makes it possible to observe these minute texture changes with images.

[0117] [Second embodiment of the present invention] Figure 5 shows a sample measuring device A3, which is a second embodiment of the present invention.

[0118] Unlike the sample measuring devices A1 and A2 described above, this sample measuring device A3 is characterized by having an equivalent surface 101 that is optically equivalent to the Fourier plane 100 of the objective lens 2, and the intensity conversion element 3 is arranged on this equivalent surface 101 that is transferred to the light source unit 4 side.

[0119] Furthermore, in the sample measuring device A3, the combination of lenses 70 and 71 transfers a surface 101 that is optically equivalent to the Fourier plane 100 to a position on the light source unit 4 side. When viewed from the light source unit 4 side, lens 70 converts the inverse space image to a real space image, and lens 71 converts the real space image to an inverse space image.

[0120] In the sample measuring device A3, the optical path of the incident light incident on the target sample 1 can be controlled by the intensity conversion element 3 arranged on the equivalent surface 101.

[0121] The intensity conversion element 3 of the sample measuring device A3 shown in Figure 5 controls the transmittance so that light is transmitted to the section corresponding to the angle of incidence of the incident light ray L9 onto the target sample 1.

[0122] In Figure 5, the light source unit 4 is shown positioned near the equivalent surface 101, but it is not necessarily required that the light source unit 4 be positioned near the equivalent surface 101. For example, it is possible to install the light source unit 4 at a location away from the equivalent surface 101.

[0123] In this sample measurement device A3, if the surface of the target sample 1 can be treated as an ideal plane without minute inclines or steps, the incident light ray L9 is not scattered at the sample surface, but is reflected by a reflected light ray L10 having a reflection angle equal to the angle of incidence, and this reflected light ray L10 can be detected by the image sensor 6.

[0124] Furthermore, the image sensor 6 can determine the reflectance of the reflected light L10, which is the result of specular reflection of the incident light L9 by the surface of the target sample 1.

[0125] Furthermore, if the surface of the target sample 1 cannot be treated as an ideal surface (for example, if there are slight inclines or steps), the sample measurement device A3 will also detect the light (reflected light L11) scattered from the surface of the target sample 1 by the image sensor 6.

[0126] Furthermore, if the surface of the target sample 1 can be treated as an ideal plane without minute inclines or steps, it is possible to detect light that is specularly reflected at different incident angles by changing the section that transmits light among the multiple sections of the intensity conversion element 3 according to the incident light at different incident angles.

[0127] According to this, by changing the light-transmitting section within each section of the intensity conversion element 3, it becomes possible to select any angle for the incident angle of light on the surface of the target sample, and to acquire and observe an image of the sample surface using light with each incident angle. In other words, it is possible to observe images with different reflectances (different light intensities) for each incident angle.

[0128] Furthermore, with the sample measurement device A3, if a thin film structure is present on the surface of the target sample, it is possible to observe the thickness of the thin film using imagery.

[0129] For example, as shown in the left diagram of Figure 6(a), a thin film T1 exists in a certain first range 10 on the surface of the target sample.

[0130] When light is shone into this first range 10 at a constant incident angle, two light paths are created: a light ray L12 that reflects off the surface of the thin film T1, and a light ray L13 that reflects off the surface of the substrate on the inner side (lower side in the figure) of the thin film T1. In addition, because the light ray L13 travels a longer distance by passing through the interior of the thin film T1, there is a difference in the optical path length between the light rays L12 and L13.

[0131] Depending on the thickness of this thin film T1, the difference in the optical path lengths of light rays L12 and L13 changes, causing the two rays to interfere. For example, if the difference in optical path lengths is an integer multiple of one wavelength, the two rays reinforce each other, resulting in a stronger reflected light intensity. If the difference in optical path lengths is an integer multiple of one wavelength and half a wavelength, the two rays weaken each other, resulting in zero reflected light intensity. Different reflected light intensities can be obtained depending on this difference in optical path lengths.

[0132] Here, by changing the light-transmitting section using the intensity conversion element 3 arranged on the equivalent surface 101, the incident angle of the irradiated light changes, and it becomes possible to irradiate the same first range 10 (thickness of the thin film T1) with light rays L14 and L15 at different incident angles. Changing the incident angle changes the interference effect of the two rays, and the resulting reflected light intensity also changes.

[0133] Then, by detecting the reflected light intensity using the intensity conversion element 3 while changing the position of the light-transmitting section (arbitrarily selecting the angle of incidence of light), a light vibration pattern (see Figure 6(b)) is obtained. In Figure 6(b), the horizontal axis corresponds to the angle of incidence, and the vertical axis corresponds to the reflected light intensity.

[0134] For example, the graph indicated by the symbol B1 in Figure 6(b) is the vibration pattern obtained from the thin film T1 in the first range 10. By analyzing this vibration pattern B1, the optical properties of the target sample can be determined. The optical properties are the film thickness and optical constants of the thin film T1. The optical constants are the refractive index (n) and extinction coefficient (k) in the first range 10.

[0135] In this way, by using the intensity conversion elements 3 arranged on the equivalent surface 101 to irradiate the target sample with light at different incident angles and analyzing the resulting light vibration patterns, parameters such as the film thickness, refractive index (n), and extinction coefficient (k) of the thin film can be obtained for each region of the sample surface.

[0136] Furthermore, even among target samples that contain thin films, the thickness of the thin film may vary depending on the differences in surface shape. In the second range 11 of the target sample shown in the center of Figure 6(a), the thickness of the thin film T1 in the second range 11 differs from the thickness of the thin film T1 in the first range 10 shown in the left of Figure 6(a) due to a step in the substrate.

[0137] In this second range 11, when light is shone while changing the angle of incidence, for example, the reflection intensity of each light can be obtained through the interference of light rays L16 and L17, and the interference of light rays L18 and L19 (see the center diagram in Figure 6(a)).

[0138] Furthermore, as the thickness of the thin film T1 changes, the vibration pattern in the second range 11 (graph labeled B2 in Figure 6(b)) shows a different shape from the vibration pattern B1 in the first range 10.

[0139] By analyzing the vibration pattern B2 in this second range 11, parameters such as the film thickness, refractive index (n), and extinction coefficient (k) of the thin film can be obtained for the second range 11.

[0140] Furthermore, with the sample measurement device A3, even for structures where multiple thin films are stacked on the surface of the target sample, if there is a difference in refractive index between the thin films and reflection occurs at the interface, it is possible to perform image observation including information about the thickness of each thin film.

[0141] For example, in the case of a structure in which multiple thin films (thin film T1 and thin film T2) are stacked, as shown in the third range 12 of the target sample in the right figure of Figure 6(a), the thickness and optical constants of each film can be determined by irradiating the third range 12 with light (for example, light rays L20 to L22) and analyzing the resulting vibration pattern.

[0142] In this sample measuring device A3, the optical path of the incident light is controlled for each section corresponding to the incident angle of the incident light by the intensity conversion element 3 arranged on the equivalent surface 101, thereby enabling efficient determination of optical physical properties in each section (incident angle).

[0143] Furthermore, as mentioned above, even when the substrate shape or thin film thickness varies from region to region on the surface of the same sample, optical properties can be determined for each minute region by performing measurements while changing the angle of incidence of the incident light.

[0144] Furthermore, the optical properties of each minute region can be acquired collectively through image processing of the image information detected by the image sensor 6.

[0145] Furthermore, in the sample measurement device A3, by controlling the incident angle of light to be constant using the intensity conversion element 3, and irradiating target samples with different surface shapes and thin film thicknesses with light, differences in the degree of light interference occur depending on the position on the sample surface, allowing for the observation of different light intensities at each position. In other words, the uniformity of the thin film thickness can be confirmed in the captured image.

[0146] [Third Embodiment of the Present Invention] Figure 7 shows a sample measuring device A4, which is a third embodiment of the present invention.

[0147] Unlike the sample measuring devices A1, A2, and A3 described above, this sample measuring device A4 is characterized by having an equivalent surface 102 that is optically equivalent to the Fourier plane 100 of the objective lens 2, and the intensity conversion element 3 is arranged on the equivalent surface 102 that is transferred to the image sensor 6 side.

[0148] Furthermore, in the sample measuring device A4, the combination of lenses 72 and 73 transfers a plane 102 that is optically equivalent to the Fourier plane 100 to the position on the image sensor 6 side. When viewed from the target sample 1 side, lens 72 converts the inverse space image to a real space image, and lens 73 converts the real space image to an inverse space image.

[0149] In the sample measuring device A4, the intensity conversion element 3, which is arranged on the equivalent surface 102, can control the optical path of the reflected light reflected from the sample surface of the target sample 1.

[0150] As shown in Figure 7, the intensity conversion element 3 of the sample measuring device A4 controls the transmittance so that light is transmitted through a section corresponding to the reflection angle from the target sample 1 of the reflected light L24.

[0151] In this sample measurement device A4, if the surface of the target sample 1 can be treated as an ideal plane without minute inclines or steps, the incident light ray L23 is not scattered at the sample surface, but is reflected by a reflected light ray L24 having a reflection angle equal to the angle of incidence, and this reflected light ray L24 can be detected by the image sensor 6.

[0152] Furthermore, the image sensor 6 can determine the reflectance of the reflected light L24 obtained by specular reflection of the incident light L23 at the surface of the target sample 1.

[0153] Furthermore, in the sample measuring device A4, the incident light L23, when scattered by the sample surface of the target sample 1 (reflected light L25), attempts to pass through a different position on the equivalent surface 102 than the position through which the reflected light L24 passes. As a result, it is blocked by a section that the light from the intensity conversion element 3 cannot penetrate, and is not detected by the image sensor 6.

[0154] Furthermore, if the surface of the target sample 1 cannot be treated as an ideal surface, the sample measuring device A4 may detect the incident light ray L230, which has a different incident angle from the incident light ray L23, as scattered at the sample surface of the target sample 1 and reflected at the reflection angle of the reflected light ray L24, which is then detected by the image sensor 6. In other words, the reflected light ray L24 may contain both the light that was specularly reflected from the incident light ray L23 and the light that was scattered from the incident light ray L230.

[0155] Furthermore, by changing the light-transmitting section among the multiple sections of the intensity conversion element 3 to match the reflected light at different reflection angles, it is possible to detect light that has been specularly reflected at different reflection angles.

[0156] According to this, by changing the light-transmitting section within each section of the intensity conversion element 3, it becomes possible to select any angle for the reflection angle of the reflected light from the surface of the target sample, and to acquire and observe an image of the sample surface using light with each reflection angle.

[0157] Furthermore, similar to the sample measuring device A3 described above, sample measuring device A4 can perform image observation of the thin film thickness if a thin film structure is present on the surface of the target sample.

[0158] Here, unlike sample measuring device A3, sample measuring device A4 irradiates the surface of the target sample 1 with incident light at various incident angles. However, the intensity conversion element 3, which is arranged on the equivalent surface 102, can control the optical path so that reflected light at a constant reflection angle is transmitted.

[0159] In this sample measuring device A4, for example, as shown in the left diagram of Figure 6(a), if the target sample is within a first range 10, multiple light rays at different incident angles (rays L12 and L13) will be irradiated simultaneously. However, since the intensity conversion element 3 extracts reflected light at a specific reflection angle, the image sensor 6 can detect the reflected intensity of light at a constant reflection angle (incident angle).

[0160] Therefore, by detecting the reflected light intensity while changing the position of the light-transmitting section in the intensity conversion element 3 (while arbitrarily selecting the light reflection angle), a light vibration pattern can be obtained, similar to the sample measurement device A3. Furthermore, by analyzing this vibration pattern, the optical properties of the target sample (thickness of the thin film T1 and optical constants) can be determined.

[0161] Specifically, by using the sample measurement device A4 and the intensity conversion elements 3 arranged on the equivalent surface 102 to extract light at different reflection angles from the target sample, and by analyzing the vibration patterns of the obtained light, parameters such as the film thickness, refractive index (n), and extinction coefficient (k) of the thin film can be obtained for each region of the sample surface.

[0162] [Fourth Embodiment of the Present Invention] Figure 8 shows a sample measuring device A5, which is a fourth embodiment of the present invention.

[0163] Unlike the various sample measuring devices (A1 to A4) described so far, this sample measuring device A5 is characterized in that the intensity conversion element 3 is arranged at two positions: an equivalent surface 101 which is optically equivalent to the Fourier surface 100 of the objective lens 2 and is transferred to the light source unit 4 side, and an equivalent surface 102 which is optically equivalent to the Fourier surface 100 and is transferred to the image sensor 6 side.

[0164] Furthermore, in the sample measuring device A5, the combination of lens 70 and lens 71 transfers the equivalent surface 101 to the position on the light source unit 4 side, and the combination of lens 72 and lens 73 transfers the equivalent surface 102 to the position on the image sensor 6 side.

[0165] In the sample measurement device A5, the intensity conversion element 3 located on the equivalent surface 101 on the light source unit 4 side controls the optical path of incident light incident on the target sample 1, and the intensity conversion element 3 located on the equivalent surface 102 on the image sensor 6 side controls the optical path of reflected light reflected from the surface of the target sample 1.

[0166] Furthermore, Figure 8 shows an example of controlling light (a combination of incident ray L1 and reflected ray L2) where the angle of incidence and the angle of reflection are the same, and the optical paths of the incident and reflected light are axially symmetric with respect to the optical axis of objective lens 2.

[0167] As shown in Figure 8, in the sample measuring device A5, the intensity conversion element 3, which is located on the equivalent surface 101 on the light source unit 4 side, controls the transmittance so that light is transmitted to the section corresponding to the angle of incidence of the incident light ray L1 to the target sample 1.

[0168] Furthermore, in the sample measurement device A5, the intensity conversion element 3, positioned on the equivalent surface 102 on the image sensor 6 side, controls the transmittance so that the reflected light L2, which is formed by the specular reflection of the incident light ray L1 by the target sample 1, is transmitted to a section of the target sample 1 at a position corresponding to the reflection angle.

[0169] In other words, the sample measuring device A5 uses two intensity conversion elements 3 to transmit an incident light ray L1 at a specific incident angle and irradiate the target sample 1, and transmits a reflected light ray L2 at the same angle of reflection and detects it with the image sensor 6.

[0170] As a result, the image sensor 6 can detect the reflected light L2 that is specularly reflected by the incident light L1 at the surface of the target sample 1, and detect the light that specularly reflects at a given angle of incidence. It can also determine the reflectance of the specularly reflected light.

[0171] Furthermore, the reflected light L5, which is scattered from the surface of the target sample 1 by the incident light L1, attempts to pass through a different position on the Fourier plane 100 than the position through which the reflected light L2 passes. As a result, it is blocked by a section of the intensity conversion element 3 that cannot transmit light, and is therefore not detected by the image sensor 6.

[0172] Furthermore, by changing the light-transmitting section among multiple sections in each of the two intensity conversion elements 3 to match the incident light at different incident angles, it is possible to detect light that is specularly reflected at different incident angles.

[0173] According to this, by changing the light-transmitting section within each of the two intensity conversion elements 3, it becomes possible to select any angle for both the incident angle of light on the surface of the target sample and the reflection angle of light reflected from the sample surface, and then acquire and observe an image of the sample surface using the light corresponding to the selected angle.

[0174] Next, using Figure 9, we will describe the measurement using sample measuring device A6 in which the intensity conversion element 3 is arranged on the equivalent surface 101 on the light source unit 4 side and the equivalent surface 102 on the image sensor 6 side, similar to sample measuring device A5. The measurement using sample measuring device A6 is a modified example of the fourth embodiment of the present invention.

[0175] Figure 9 shows the sample measuring device A6. In the sample measuring device A6, the intensity conversion element 3, located on the equivalent surface 101 on the light source unit 4 side, controls the transmittance so that light passes through a section corresponding to the angle of incidence of the incident light ray L1 onto the target sample 1.

[0176] Furthermore, the intensity conversion element 3, positioned on the equivalent surface 102 of the image sensor 6, controls the transmittance so that the light from the incident light ray L1 passes through a section corresponding to the reflection angle of the reflected light ray L5 scattered from the surface of the target sample 1.

[0177] In other words, the difference from the sample measuring device A5 described above is that, among the multiple compartments of the intensity conversion element 3 arranged on the equivalent surface 102 on the image sensor 6 side, light is transmitted to the compartment through which light scattered at the sample surface (reflected light L5) passes, rather than light specularly reflected by the target sample 1 (reflected light L2) with respect to the incident light L1.

[0178] The two intensity conversion elements 3 of this sample measuring device A6 transmit incident light rays L1 at a specific incident angle and irradiate the target sample 1. These elements then transmit the reflected light rays L5 of the diffuse reflection scattered from the surface of the target sample 1, which can then be detected by the image sensor 6.

[0179] In this way, the sample measuring device A6 transmits the incident light ray L1 through the intensity conversion element 3 located on the equivalent surface 101 on the light source unit 4 side, and extracts the reflected light ray L5 scattered from the sample surface by the intensity conversion element 3 located on the equivalent surface 102 on the image sensor 6 side. This reflected light ray L5 is then detected by the image sensor 6, and image information can be acquired.

[0180] The light scattered from the surface of this sample is caused by minute inclinations or steps on the sample surface, and the sample measurement device A6 makes it possible to observe these minute texture changes with images.

[0181] Furthermore, if light diffraction occurs on the surface of the sample when light is irradiated onto the target sample 1, dark-field observation using only diffracted light of a specific order can be performed using the configuration of sample measuring device A5 or sample measuring device A6.

[0182] Here, if a periodic structure with a scale roughly equivalent to the wavelength of the incident light exists on the surface of the target sample 1, then diffraction of light occurs. In this target sample 1, for incident light at a certain incident angle, not only is the reflected light (zero-order diffracted light) that is specularly reflected strongly detected, but among the reflected light at reflection angles different from the specularly reflected light, there are reflection angles in which the reflected light periodically interferes with each other, resulting in constructive interference.

[0183] For example, as shown in Figure 10, if a periodic structure with a scale roughly equivalent to the wavelength of incident light exists in a region 13 on the surface of the target sample 1, when light is incident on that region 13, interference of reflected light occurs, reflecting the periodic structure.

[0184] Here, the incident light L26 in Figure 10 generates not only specularly reflected light L27, but also reflected light L28 and L29 with altered reflection angles, in accordance with the fine shape of the periodic structure.

[0185] In Figure 10, the incident angle of the incident light L26 is θ. 1、 Let the reflection angle of reflected light L27 be -θ1. Also, let the reflection angle of reflected light L28 be -θ2, and the reflection angle of reflected light L29 be -θ3. Furthermore, in terms of angular quantities, θ2 deviates less from θ1 than θ3.

[0186] Furthermore, the reflected light L27 at a reflection angle of -θ1, which is specularly reflected from the incident light L26 at an incident angle of θ1, is defined as the "zero-order diffracted light." Similarly, the reflected light L28 at a reflection angle of -θ2 is defined as the "first-order diffracted light," and the reflected light L29 at a reflection angle of -θ3 is defined as the "second-order diffracted light."

[0187] When such "first-order diffracted light" or "second-order diffracted light" is obtained, by using two intensity conversion elements 3 to transmit incident light L26 at incident angle θ1 and extract reflected light L28 at reflection angle -θ2, dark-field observation using only "first-order diffracted light" can be performed with the image sensor 6.

[0188] Similarly, by using two intensity conversion elements 3 to transmit incident light L26 at an incident angle θ1 and extracting reflected light L29 at a reflection angle -θ3, dark-field observation using only "second-order diffracted light" can be performed with the image sensor 6.

[0189] Furthermore, it is possible to use diffracted light of different orders, not just first-order or second-order diffracted light, if such diffracted light of different orders can be obtained.

[0190] In dark-field observation using only diffracted light of a specific order, the image sensor 6 can acquire a dark-field image by controlling the optical paths of the incident and reflected light using two intensity conversion elements 3 in the sample measuring device A5 or A6.

[0191] Furthermore, when the intensity conversion element 3 on the image sensor 6 detects the reflected light while arbitrarily selecting the reflection angle, a light vibration pattern P1 with different detected light intensities is obtained depending on the difference in reflection angle (see Figure 10). In Figure 10, the light vibration pattern P1 has the horizontal axis corresponding to the reflection angle and the vertical axis corresponding to the detected light intensity.

[0192] Furthermore, in the light vibration pattern P1 of Figure 10, waveforms are obtained that reflect the intensity of detected light, such as zero-order diffracted light resulting from the interference of incident light and specularly reflected light, first-order diffracted light resulting from the interference of incident light and reflected light at a different reflection angle, or second-order diffracted light.

[0193] Furthermore, if there is another periodic structure in region 14 on the surface of the target sample 1, located at a different position from region 13, and having a different periodicity from region 13, then a light vibration pattern P2 reflecting the periodic structure of region 14 can be obtained (see Figure 10).

[0194] In this way, using the sample measuring device A5 or A6, by controlling the incident angle of the incident light to a constant value using two intensity conversion elements 3, and detecting the reflected light while arbitrarily selecting the reflection angle of the reflected light, it is possible to observe an image that reflects a fine periodic structure.

[0195] [Fifth Embodiment of the Present Invention] Figure 11 shows a sample measuring device A7, which is a fifth embodiment of the present invention.

[0196] Unlike the various sample measuring devices (A1 to A5) described so far, this sample measuring device A7 is characterized in that the intensity conversion element 3 is arranged at two positions: the Fourier plane 100 of the objective lens 2, and the equivalent plane 101 which is optically equivalent to the Fourier plane 100 and is transferred to the light source unit 4 side.

[0197] Furthermore, in the sample measuring device A7, the combination of lens 70 and lens 71 transfers a surface 101 that is optically equivalent to the Fourier plane 100 to a position on the light source unit 4 side.

[0198] In the sample measuring device A7, the intensity conversion element 3 arranged on the equivalent surface 101 controls the optical path of incident light incident on the target sample 1, and the intensity conversion element 3 arranged on the Fourier surface 100 controls the optical paths of both the incident light incident on the target sample 1 and the reflected light reflected from the surface of the target sample 1.

[0199] Furthermore, Figure 11 shows an example of controlling light (a combination of incident ray L1 and reflected ray L2) where the angle of incidence and the angle of reflection are the same, and the optical paths of the incident and reflected light are axially symmetric with respect to the optical axis of objective lens 2.

[0200] In the sample measuring device A7 shown in Figure 11, the intensity conversion element 3, positioned on the equivalent surface 101, controls the transmittance so that light passes through the section corresponding to the angle of incidence of the incident light ray L1 onto the target sample 1.

[0201] Furthermore, in the sample measuring device A7, the intensity conversion element 3 positioned on the Fourier plane 100 controls the transmittance so that light passes through the section corresponding to the angle of incidence of the incident light ray L1 onto the target sample 1, and the section corresponding to the angle of reflection of the reflected light ray L2 from the target sample 1.

[0202] In other words, the sample measuring device A7 uses two intensity conversion elements 3 to transmit an incident light ray L1 at a specific incident angle and irradiate the target sample 1, and transmits a reflected light ray L2 at the same angle of reflection and detects it with the image sensor 6.

[0203] As a result, the image sensor 6 can detect the reflected light L2 that is specularly reflected by the incident light L1 at the surface of the target sample 1, and detect the light that specularly reflects at a given angle of incidence. It can also determine the reflectance of the specularly reflected light.

[0204] Furthermore, the reflected light L5, which is scattered from the surface of the target sample 1 by the incident light L1, attempts to pass through a different position on the Fourier plane 100 than the position through which the reflected light L2 passes. As a result, it is blocked by a section of the intensity conversion element 3 that cannot transmit light, and is therefore not detected by the image sensor 6.

[0205] Furthermore, by changing the light-transmitting section among multiple sections in each of the two intensity conversion elements 3 to match the incident light at different incident angles, it is possible to detect light that is specularly reflected at different incident angles.

[0206] According to this, by changing the light-transmitting section within each of the two intensity conversion elements 3, it becomes possible to select any angle for both the incident angle of light on the surface of the target sample and the reflection angle of light reflected from the sample surface, and then acquire and observe an image of the sample surface using the light corresponding to the selected angle.

[0207] Next, a measurement using sample measuring device A8, in which the intensity conversion element 3 is arranged on the Fourier plane 100 and the equivalent plane 101 on the light source 4 side, similar to sample measuring device A7, will be explained with reference to Figure 12. The measurement using sample measuring device A6 is a modification of the fifth embodiment of the present invention.

[0208] Figure 12 shows the sample measuring device A8. In the sample measuring device A8, the intensity conversion element 3, which is arranged on an equivalent surface 101, controls the transmittance so that light is transmitted through a section corresponding to the angle of incidence of the incident light ray L1 onto the target sample 1.

[0209] Furthermore, the intensity conversion element 3, positioned on the Fourier plane 100, controls the transmittance so that light passes through a section corresponding to the angle of incidence of the incident light ray L1 onto the target sample 1, and a section corresponding to the reflection angle of the reflected light ray L5 scattered from the surface of the target sample 1.

[0210] In other words, the difference from the sample measuring device A7 described above is that, among the multiple compartments of the intensity conversion element 3 arranged on the Fourier plane 100, light is transmitted to the compartment through which light scattered at the sample surface (reflected light L5) passes, rather than light specularly reflected by the target sample 1 (reflected light L2) with respect to the incident light L1.

[0211] The two intensity conversion elements 3 of this sample measuring device A8 transmit incident light rays L1 at a specific incident angle and irradiate the target sample 1. These elements then transmit the reflected light rays L5 of the diffuse reflection scattered from the surface of the target sample 1, which can then be detected by the image sensor 6.

[0212] In this way, the sample measuring device A8 transmits the incident light ray L1 through the intensity conversion element 3 placed on the equivalent surface 101 on the light source unit 4 side, and extracts the reflected light ray L5 scattered from the sample surface by the intensity conversion element 3 placed on the Fourier plane 100. This reflected light ray L5 is then detected by the image sensor 6, and image information can be acquired.

[0213] The light scattered from the surface of this sample is caused by minute inclines or steps on the sample surface, and the A8 sample measurement device makes it possible to observe these minute texture changes with images.

[0214] Furthermore, using the configuration of sample measuring device A7 or sample measuring device A8, dark-field observation can be performed using only diffracted light of a specific order, similar to sample measuring device A5 or sample measuring device A6 described above.

[0215] When performing dark-field observation using only diffracted light of a specific order with sample measuring device A7 or sample measuring device A8, the intensity conversion element 3 arranged on the equivalent surface 101 on the light source unit 4 side controls the optical path so that the incident light has a constant incident angle, and the intensity conversion element 3 arranged on the Fourier plane 100 controls the optical path so that reflected light with different reflection angles is extracted.

[0216] Furthermore, using the configuration of sample measuring device A7 or sample measuring device A8, it is possible to observe captured images that reflect the periodic structure of the surface of the target sample, similar to the above-mentioned sample measuring device A5 or sample measuring device A6.

[0217] When observing an image reflecting the periodic structure of the surface of a target sample using the sample measuring device A7 or A8, the intensity conversion element 3 placed on the equivalent surface 101 on the light source unit 4 side controls the optical path so that the incident light has a constant incident angle, and the intensity conversion element 3 placed on the Fourier plane 100 extracts the reflected light while varying the reflection angle.

[0218] As an embodiment of the present invention, although not shown in the figures, a sample measuring device may also be employed in which intensity conversion elements 3 are arranged at two positions: the Fourier plane 100 of the objective lens 2 and an equivalent plane 102 that is optically equivalent to the Fourier plane 100 and is transferred to the image sensor 6 side.

[0219] In this case, the intensity conversion element 3 arranged on the Fourier plane 100 can provide the same functionality as the sample measuring device A1 (see Figure 3) and sample measuring device A2 (see Figure 4) described above.

[0220] Next, an example of the intensity distribution pattern of the intensity conversion element 3 used in the embodiment of the present invention will be described with reference to the drawings.

[0221] Here, Figures 13 and 14 illustrate an example of an intensity conversion element 3 arranged on the Fourier plane 100 in the first embodiment of the present invention described above. This intensity conversion element 3 arranged on the Fourier plane 100 is an element that can simultaneously control the optical path of incident light and the optical path of reflected light with a single intensity conversion element 3.

[0222] In Figures 13 and 14, the "upper diagram" in each figure is a schematic plan view of the intensity conversion element that corresponds to all directions (including any direction of 360 degrees on the plane of the intensity conversion element 3) without restricting the azimuth angle of the incident and reflected light.

[0223] Furthermore, in Figures 13 and 14, the "middle diagram" in each figure is a schematic plan view of an intensity conversion element corresponding to a specific direction in which the azimuth angle of the incident and reflected light is restricted to a certain direction.

[0224] In the intensity distribution patterns corresponding to specific directions, as shown in the middle diagrams of Figures 13 and 14, it becomes possible to control the azimuth angle of incident or reflected light and analyze the physical properties at a specific angle.

[0225] Furthermore, in Figures 13 and 14, the "lower panel" of each figure is a schematic cross-sectional view of the intensity conversion element 3, objective lens 2, and target sample 1 as seen along the incident plane of the incident light. Note that the transmitted portion in the lower panel of each figure is only denoted by the same reference numeral as the transmitted portion in the middle panel of each figure, but the transmitted portion in the upper panel of each figure is formed in the same location.

[0226] For example, when incident light L100 is incident on a target sample 1 at a specific incident angle θ1, and the reflected light L101 with a reflection angle -θ1 that is specularly reflected by the target sample 1 is extracted (see the lower part of Figure 13(a)), an intensity conversion element 3 with the intensity distribution pattern shown in the upper part of Figure 13(a) or the middle part of Figure 13(a) can be used.

[0227] In the upper part of Figure 13(a), the intensity conversion element 3 is controlled to have multiple sections such that a ring-shaped transparent section 30 with a certain width is formed. This transparent section 30 is the position through which light with an incident angle θ1 and a reflection angle -θ1 is transmitted.

[0228] Furthermore, the intensity conversion element 3 in the middle section of Figure 13(a) is controlled to have multiple sections such that a transparent section 300 and a transparent section 301 of a certain size are formed. The transparent section 300 is the position through which light with an incident angle θ1 is transmitted, and the transparent section 301 is the position through which light with a reflection angle -θ1 is transmitted.

[0229] Furthermore, for example, when incident light L102 is incident on a target sample 1 at a specific incident angle θ2, and the reflected light L103 with a reflection angle of -θ2 that is specularly reflected by the target sample 1 is extracted (see the lower part of Figure 13(b)), the intensity conversion element 3 with the intensity distribution pattern shown in the upper part of Figure 13(b) or the middle part of Figure 13(b) can be used.

[0230] In the upper part of Figure 13(b), the intensity conversion element 3 is controlled to have multiple sections such that a ring-shaped transparent section 31 with a certain width is formed. This transparent section 31 is the position through which light with an incident angle θ2 and a reflection angle -θ2 is transmitted.

[0231] Furthermore, the intensity conversion element 3 in the middle section of Figure 13(b) is controlled to have multiple sections such that a transparent section 302 and a transparent section 303 of a certain size are formed. The transparent section 302 is the position through which light with an incident angle θ2 is transmitted, and the transparent section 303 is the position through which light with a reflection angle -θ2 is transmitted.

[0232] The intensity conversion element 3 shown in Figures 13(a) and 13(b) is an intensity distribution pattern that can be applied to the sample measuring device A1 of the first embodiment of the present invention described above.

[0233] Furthermore, for example, when incident light L104 is incident on a target sample 1 at a specific incident angle θ3, and reflected light L105 with a reflection angle of -θ4 scattered by the target sample 1 is extracted (see the lower panel of Figure 13(c)), the intensity conversion element 3 with the intensity distribution pattern shown in the upper panel of Figure 13(c) or the middle panel of Figure 13(c) can be used.

[0234] The intensity conversion element 3 in the upper part of Figure 13(c) is controlled to have multiple sections such that a semi-circular transparent section 32 with a constant width and a semi-circular transparent section 33 with different radii and a constant width are formed. The transparent section 32 is the position through which light with an incident angle θ3 is transmitted, and the transparent section 33 is the position through which light with a reflection angle -θ4 is transmitted.

[0235] Furthermore, the intensity conversion element 3 in the middle section of Figure 13(b) is controlled to have multiple sections such that a transmissive section 304 and a transmissive section 305 of a certain size are formed. The transmissive section 304 is the position through which light with an incident angle θ3 is transmitted, and the transmissive section 304 is the position through which light with a reflection angle -θ4 is transmitted.

[0236] The intensity conversion element 3 shown in Figure 13(c) is an intensity distribution pattern that can be applied to the sample measuring device A2 of the first embodiment of the present invention described above.

[0237] Furthermore, in the fourth embodiment of the present invention, the two intensity conversion elements 3, the equivalent surface 101 transferred to the light source unit 4 side and the equivalent surface 102 transferred to the image sensor 6 side, can also be the same intensity conversion elements 3 shown in Figures 13(a) to 13(c), but divided into left and right sections in the figures.

[0238] That is, for example, the left half of the intensity conversion element 3 in the middle diagram of Figure 13(a) (the side with the transparent portion 300) can be placed on the equivalent surface 101 transferred to the light source 4 side, and the right half of the intensity conversion element 3 in the middle diagram of Figure 13(a) (the side with the transparent portion 301) can be placed on the equivalent surface 102 transferred to the image sensor 6 side.

[0239] In a sample measuring device to which the present invention is applied, the numerical aperture (NA) of the objective lens 2 can also be controlled by controlling multiple compartments of the intensity conversion element 3.

[0240] For example, by controlling multiple sections so that a circular transparent section 34 occupies all or most of the intensity conversion element 3, as shown in the upper diagram of Figure 14(a), or a transparent section 306 occupies a wide area along a specific azimuth angle of the intensity conversion element 3, as shown in the middle diagram of Figure 14(a), it becomes possible to observe the target sample 1 with a high resolution under a microscope (see the lower diagram of Figure 14(a)).

[0241] Furthermore, by controlling multiple sections such as the smaller transparent section 35 formed in the center of the intensity conversion element 3, as shown in the upper diagram of Figure 14(b), or the smaller transparent section 306 formed in the center of the intensity conversion element 3 along a specific azimuth angle, as shown in the middle diagram of Figure 14(b), only light close to vertical scattering can be detected from the target sample 1.

[0242] According to this method, an image with high contrast can be obtained, similar to observation with a low-magnification imaging camera, making it possible to acquire an observation image in which minute steps and other irregularities on the surface of the target sample 1 are easily visible.

[0243] As described above, the sample measuring device of the present invention is capable of performing both shape observation of the sample surface, including information on the fine shape of the sample surface, and measurement of optical properties with a single device, and can obtain observation information while selecting any angle for the angle of incidence, reflection, or azimuth of light.

[0244] Although the present invention has been specifically described above based on embodiments, it goes without saying that the present invention is not limited to the above embodiments and can be modified in various ways without departing from its essence. [Explanation of symbols]

[0245] A1 Sample measuring device A2 Sample measuring device A3 Sample Measurement Device A4 Sample Measurement Device A5 Sample measuring device A6 Sample Measurement Device A7 Sample measuring device A8 Sample measuring device 1. Target sample 2. Objective lens 3. Intensity conversion element 4 Light source section 5. Non-polarized beam splitter 6 Image Sensors 10. 1st Scope 11. Second Scope 12 Third range 13 areas 14 areas 30 Transparent part 31 Transparent part 32 Transparent part 33 Transparent part 34 Transparent part 35 Transparent part 70 lenses 71 Lens 72 lenses 73 lenses 74 lenses 100 Fourier surface 101 A surface equivalent to the Fourier surface 102 (A surface equivalent to a Fourier surface) 300 Transparent part 301 Transparent part 302 Transparent part 303 Transparent part 304 Transparent part 305 Transparent part 306 Transparent part 307 Transparent part

Claims

1. Light source and A detector that receives at least a portion of the light from the aforementioned light source, which is reflected from the target sample and passes through the objective lens, The objective lens comprises an intensity conversion element having multiple compartments, each positioned on the Fourier plane of the objective lens and on a plane optically equivalent to the Fourier plane that has been transferred to the light source side, and capable of individually controlling the intensity of transmitted light. The intensity conversion element arranged on the Fourier plane transmits light before it enters the target sample and light reflected from the target sample. The intensity conversion element, which is located on the equivalent surface transferred to the light source side, receives light before it is incident on the target sample. Sample measuring device.

2. The detector is configured to measure polarization The sample measuring device according to claim 1.

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