Inspection apparatus and inspection method

Abstract

To provide an inspection apparatus and an inspection method, each enabling highly accurate determination of a defect of a film.SOLUTION: An inspection apparatus 1 according to the present disclosure, comprises: a first optical system 10 that illuminates a film 50 with a first light L1 transmitted through the film 50 and receives a first observation light R1 from a first surface 51 side of the film 50; a second optical system 20 that illuminates the film 50 from the first surface 51 side with a second light L2 reflected by the first surface 51 of the film 50 and receives a second observation light R2 from the first surface 51 side; and a discrimination portion 31 that discriminates whether or not a position of a defect DF of the film 50 is the defect DF above the first surface 51 of the film 50 or the defect DF below the first surface 51 based on a combination of an observation result of a bright field observation in the first optical system 10 and the observation result of the dark field observation in the second optical system 20.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an inspection device and an inspection method. [Background technology]

[0002] Patent Document 1 proposes an inspection method using a dark-field illumination system that can distinguish whether a foreign particle on a pellicle is on the front surface or the back surface of the pellicle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-258241 Summary of the Invention [Problem to be solved by the invention]

[0004] It is desirable to determine with higher accuracy whether defects in a film such as a pellicle are defects on the surface or back surface of the film.

[0005] The present disclosure has been made to solve the above problems, and aims to provide an inspection device and an inspection method that can determine film defects with high accuracy. [Means for solving the problem]

[0006] The inspection device according to the present disclosure comprises a first optical system that illuminates the film with a first light that passes through the film and receives the first observation light from the first surface side of the film; a second optical system that illuminates the film from the first surface side with a second light that is reflected by the first surface of the film and receives the second observation light from the first surface side; and a determination unit that determines whether the position of a defect in the film is above the first surface of the film or below the first surface based on a combination of the observation results of bright-field observation with the first optical system and the observation results of dark-field observation with the second optical system, with the first surface side in the thickness direction of the film defined as the top and the second surface side opposite the first surface defined as the bottom.

[0007] In the above inspection device, the judgment unit may judge the defect to be above the first surface if the defect is detected in both the observation results from the first optical system and the observation results from the second optical system, and may judge the defect to be below the first surface if the defect is detected in the observation results from the first optical system and not detected in the observation results from the second optical system.

[0008] In the above inspection device, the judgment unit may judge the defect to be caused by a foreign substance on the surface of the first surface when the defect is detected in both the observation results from the first optical system and the observation results from the second optical system, and may judge the defect to be caused by a foreign substance on the surface of the second surface when the defect is detected in the observation results from the first optical system and not detected in the observation results from the second optical system.

[0009] In the above-described inspection device, the first optical system uses oblique incidence illumination in which the optical axis of the first light is perpendicular to the first surface, and the second optical system uses oblique incidence illumination in which the optical axis of the second light is tilted with respect to the first surface, and the objective lens that receives the second observation light in the second optical system may be common to the objective lens that receives the first observation light in the first optical system.

[0010] In the above inspection device, the first optical system may illuminate the film from the first surface side with the first light, and the objective lens may focus the first light of the first optical system onto the film.

[0011] In the above-mentioned inspection device, the first light in the first optical system may include a wavelength of 600 nm or more and 750 nm or less, the second light in the second optical system may include a wavelength of 350 nm or more and 550 nm or less, and the incident angle of the second light in the second optical system may include a wavelength of 60° or more and 85° or less.

[0012] In the above inspection device, the judgment unit may judge the shape, including the size, of the defect based on the observation results from the first optical system, and, if the shape of the defect is a predetermined shape, may judge the position of the defect in the thickness direction of the film.

[0013] In the above inspection device, the second optical system performs modified dark-field observation by performing at least one of the following: a polarization state change to change the polarization state of the second light to a polarization state that increases the amount of light that transmits through the film; a wavelength change to change the wavelength of the second light to a wavelength that increases the amount of light that transmits through the film; and an incident angle change to change the incident angle of the second light to an incident angle that increases the amount of light that transmits through the film; and the judgment unit may obtain height information of the defect from the results of the modified dark-field observation and classify the defect.

[0014] In the above inspection apparatus, the film may include a pellicle attached to a photomask.

[0015] In the inspection apparatus, the depth of focus of the objective lens may be smaller than the distance between the photomask and the pellicle.

[0016] In the above inspection apparatus, the film may include a pellicle attached to a photomask, and the first optical system may observe a pattern surface formed on the photomask.

[0017] In the inspection apparatus, the photomask may include one for EUV exposure.

[0018] The inspection method according to the present disclosure comprises the steps of: performing bright-field observation using a first optical system that illuminates the film with a first light that transmits through the film and receives the first observation light from the first surface side of the film; performing dark-field observation using a second optical system that illuminates the film from the first surface side with a second light that reflects off the first surface of the film and receives the second observation light from the first surface side; and determining with a determination unit whether the position of a defect in the film is above the first surface of the film or below the first surface, based on a combination of the observation results of the bright-field observation using the first optical system and the observation results of the dark-field observation using the second optical system, when the first surface side in the thickness direction of the film is defined as the top and the second surface side opposite the first surface is defined as the bottom. [Effects of the Invention]

[0019] According to the present disclosure, it is possible to provide an inspection device and an inspection method that can determine defects in a film with high accuracy. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a configuration diagram illustrating an inspection device according to a first embodiment. [Figure 2] 1 is a graph illustrating the relationship between the angle of incidence on a pellicle for EUV exposure and transmittance in the inspection device of embodiment 1, where the horizontal axis represents the angle of incidence on the pellicle and the vertical axis represents the transmittance on the pellicle. [Figure 3] 4 is a diagram illustrating the observation results of bright-field observation and dark-field observation in the inspection device according to the first embodiment, showing a case where a defect exists on the first surface of the film. FIG. [Figure 4] 4 is a diagram illustrating the results of bright-field observation and dark-field observation in the inspection device according to the first embodiment, showing a case where a defect exists on the second surface of the film. FIG. [Figure 5] 4 is a diagram illustrating an example of an observation result determined by a determining unit in the inspection device according to the first embodiment. FIG. [Figure 6] 1 is a block diagram illustrating a processing device in an inspection device according to a first embodiment. [Figure 7]FIG. 2 is a flowchart illustrating an inspection method using the inspection device according to the first embodiment. [Figure 8] FIG. 10 is a flowchart illustrating another inspection method using the inspection device according to the first embodiment. [Figure 9] FIG. 10 is a configuration diagram illustrating an inspection device according to a second embodiment. [Figure 10] 10 is a cross-sectional view illustrating an example of the arrangement of the objective lens and mirror in the second optical system in the inspection device according to the second embodiment, showing a cross section taken along line AA in FIG. 9. [Figure 11] 10 is a cross-sectional view illustrating an example of the arrangement of an objective lens and a mirror in a second optical system in an inspection device according to a second embodiment. FIG. [Figure 12] 10 is a diagram illustrating an example of oblique incidence illumination in the second optical system in the inspection device according to the second embodiment. FIG. [Figure 13] 10 is a diagram illustrating an example of an observation result of dark-field observation by the second optical system in the inspection device according to the second embodiment. FIG. [Figure 14] 10 is a diagram illustrating the results of bright-field observation and dark-field observation in the inspection device according to the second embodiment, showing the case where a pinhole is present in the film. FIG. [Figure 15] 10 is a graph illustrating the brightness in the observation results of bright-field observation and dark-field observation in the inspection device according to the second embodiment, where the horizontal axis indicates the position on the film along the X-axis direction and the vertical axis indicates the brightness. [Figure 16] 10 is a graph illustrating the brightness in the observation results of bright-field observation and dark-field observation in the inspection device according to the second embodiment, where the horizontal axis indicates the position on the film along the X-axis direction and the vertical axis indicates the brightness. [Figure 17] 10 is a diagram illustrating the results of bright-field observation and dark-field observation in the inspection device according to the second embodiment, showing a case where particles are present on the first surface of the film. FIG. [Figure 18] 10 is a diagram illustrating an example of an observation result determined by a determining unit in the inspection device according to the second embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, a specific configuration of this embodiment will be described with reference to the drawings. The following description shows a preferred embodiment of the present disclosure, and the scope of the present disclosure is not limited to the following embodiment. In the following description, parts with the same reference numerals indicate substantially the same content.

[0022] <Embodiment 1> An inspection device and an inspection method according to a first embodiment will be described.

[0023] <Inspection equipment> FIG. 1 is a configuration diagram illustrating an inspection apparatus according to a first embodiment. As shown in FIG. 1, the inspection apparatus 1 includes a first optical system 10, a second optical system 20, and a processing device 30. The inspection apparatus 1 inspects a film 50 attached to a sample 40 for defects DF. The defects DF include foreign matter attached to the film 50. Note that the defects DF are not limited to foreign matter attached to the film 50, but may also include abnormalities in the film 50 such as protrusions formed on the surface of the film 50 (sometimes simply referred to as foreign matter on the surface of the film), holes (pinholes), or dents formed on the surface of the film 50.

[0024] The sample 40 includes, for example, a photomask. The film 50 includes, for example, a pellicle attached to the photomask. The film 50 has a first surface 51 and a second surface 52 opposite the first surface 51. The second surface 52 faces the sample 40. Therefore, the first surface 51 faces away from the sample 40. The sample 40 may include a photomask for exposure using EUV (Extreme Ultraviolet) light. In this case, the pellicle is formed to transmit EUV light. Note that the sample 40 is not limited to a photomask but may be other components such as a semiconductor substrate. The film 50 is not limited to a pellicle attached to a photomask but may be other components such as an insulating film or semiconductor film attached to a semiconductor substrate or the like via a spacer. The film 50 may be a pellicle before being attached to the photomask. In this case, the sample 40 does not need to be present near the film 50 when detecting defects DF in the film 50.

[0025] For ease of explanation, an XYZ Cartesian coordinate system is introduced. The direction perpendicular to the first surface 51 of the film 50 is defined as the Z-axis direction, and two directions perpendicular to each other in a plane perpendicular to the Z-axis direction are defined as the X-axis direction and the Y-axis direction.

[0026] The first optical system 10 includes a light source 11, a mirror 12, an objective lens 13, a wavelength selection unit 14, a lens 15, and a first detector 16. The first optical system 10 may include other components. The light source 11 generates a first light L1. The first light L1 may include a wavelength that is transmitted through the film 50. For example, the first light L1 in the first optical system 10 may include a wavelength of 600 nm or more and 750 nm or less. Specifically, the first light L1 may include light having a central wavelength at 630 nm. The first light L1 emitted from the light source 11 is reflected by the mirror 12.

[0027] The mirror 12 includes, for example, a half mirror, a non-polarizing beam splitter, etc. The mirror 12 reflects a part of the incident first light L1 toward the objective lens 13.

[0028] The objective lens 13 focuses the first light L1 of the first optical system 10 onto the film 50. Therefore, the first optical system 10 illuminates the film 50 from the first surface 51 side with the first light L1. The first optical system 10 may also illuminate the film 50 from the second surface 52 side. In this case, the sample 40 may not be provided, or the first light L1 may be light that passes through the sample 40.

[0029] The optical axis of the objective lens 13 extends in the Z-axis direction. The optical axis of the first light L1 focused by the objective lens 13 extends in the Z-axis direction. Therefore, the first optical system 10 aligns the optical axis of the first light L1 perpendicular to the first surface 51 of the film 50. The first light L1 passes through the film 50. For example, if the film 50 is a pellicle, the wavelength of the first light L1 is set to be not less than 600 nm and not more than 750 nm, and the optical axis of the first light L1 is aligned perpendicular to the first surface 51 of the film 50, so that the first light L1 passes through the film 50.

[0030] The focal depth of the objective lens 13 may be greater than the thickness of the film 50 from the first surface 51 to the second surface 52. Alternatively, the focal depth of the objective lens 13 may be smaller than the distance between the photomask and the pellicle. This allows the first optical system 10 to observe defects on the first surface 51 and the second surface 52 of the film 50 without being affected by the pattern surface of the photomask. Note that the first optical system 10 may observe the pattern surface formed on the photomask by focusing the first light L1 in the first optical system 10 on the photomask.

[0031] The objective lens 13 collects the first observation light R1 from the film 50 illuminated with the first light L1. The optical axis of the first light L1 and the optical axis of the first observation light are perpendicular to the first surface 51 and the second surface 52 of the film 50. Therefore, the objective lens 13 collects the first observation light R1 reflected by the first surface 51 and the second surface 52 of the film 50. The first observation light R1 includes the reflected light of the first light L1 reflected by the first surface 51 and the second surface 52. In this way, the first optical system 10 illuminates the film 50 with the first light L1 that transmits through the film 50 and receives the first observation light R1 from the first surface 51 side of the film 50. Even when the sample 40 is not provided or when the film 50 is illuminated from the second surface 52 side with the first light L1 that transmits through the sample 40, the first optical system 10 illuminates the film 50 with the first light L1 that transmits through the film 50 and receives the first observation light R1 from the first surface 51 side of the film 50. In this way, the first optical system 10 performs bright-field observation.

[0032] The first observation light R1 transmitted through the objective lens 13 is incident on the mirror 12. The mirror 12 transmits a portion of the first observation light R1. The first observation light R1 transmitted through the mirror 12 is incident on the wavelength selection unit 14.

[0033] The wavelength selection unit 14 includes, for example, a dichroic mirror. The wavelength selection unit 14 transmits the first observation light R1. This causes the first observation light R1 to enter the lens 15. The lens 15 collects the incident first observation light R1 and guides it to the first detector 16. It is desirable that the first observation light R1 be focused on the first detector 16. This allows the first optical system 10 to be a confocal optical system. The first detector 16 detects the first observation light R1. The first detector 16 may be a TDI (Time Delay Integration) sensor or a line sensor.

[0034] The wavelength selection unit 14 may reflect the first observation light R1 and guide it to the first detector 16 via the lens 15. The wavelength selection unit 14 is not limited to a dichroic mirror, and may be a combination of a half mirror and a bandpass filter, as long as it can guide the first observation light R1 to the first detector 16.

[0035] The first detector 16 is connected to the processing device 30 via a communication line including at least one of a wired and wireless line in a state in which information can be transmitted. The first detector 16 outputs the observation results of the bright-field observation by the first optical system 10 to the processing device 30.

[0036] The second optical system 20 includes a light source 21, a mirror 22, an objective lens 13, a wavelength selection unit 14, a lens 25, and a second detector 26. In this embodiment, the objective lens 13 that receives the second observation light R2 in the second optical system 20 is common to the objective lens 13 that receives the first observation light R1 in the first optical system 10. The wavelength selection unit 14 that selects the wavelength of the second observation light R2 in the second optical system 20 may be common to the wavelength selection unit 14 that selects the wavelength of the first observation light R1 in the first optical system 10. The second optical system 20 may further include other components.

[0037] The light source 21 generates the second light L2. The second light L2 in the second optical system 20 may include a wavelength of 350 nm or more and 550 nm or less. Specifically, the second light L2 may include light with a center wavelength of 405 nm. The second light L2 emitted from the light source 21 is incident on the mirror 22. The second light L2 emitted from the light source 21 may be incident on the mirror 22 via a polarizing element 27. The polarizing element 27 converts the polarization state of the second light L2. For example, when the second light L2 is incident on the film 50, the polarizing element 27 converts the polarization state so that the second light L2 includes S-polarized light.

[0038] The mirror 22 reflects the incident second light L2 toward the first surface 51 of the film 50. The optical axis of the second light L2 incident on the first surface 51 is tilted with respect to the first surface 51. In this way, the second optical system 20 uses oblique incidence illumination in which the optical axis of the second light L2 is tilted with respect to the first surface 51. The second light L2 that is obliquely incident on the first surface 51 is reflected by the first surface 51. For example, the second light L2 that is incident on the first surface 51 may include S-polarized light.

[0039] 2 is a graph illustrating the relationship between the angle of incidence on a pellicle for EUV exposure and transmittance in the inspection apparatus 1 according to embodiment 1, where the horizontal axis represents the angle of incidence on the pellicle and the vertical axis represents the transmittance through the pellicle. In FIG. 2, the transmittance of S-polarized light having a central wavelength of 750 nm and S-polarized light having a central wavelength of 550 nm are shown.

[0040] 2, the larger the incident angle, the smaller the transmittance. In this embodiment, the incident angle of the second light L2 in the second optical system 20 is in the range of 60° to 85°. Specifically, the incident angle of the second light L2 is in the range of 70° or more, which is the Brewster angle.

[0041] For example, when the film 50 is a pellicle, the wavelength of the second light L2 is set to 350 nm or more and 550 nm or less, the second light L2 includes S-polarized light, and the incident angle of the optical axis of the second light L2 is set to 60° or more and 85° or less, so that the second light L2 can be reflected by the first surface 51 of the film 50.

[0042] The objective lens 13 collects second observation light R2, which has a component in the +Z axis direction, from the first surface 51 side, out of the light that is the second light L2 reflected by the film 50. The second observation light R2 includes, for example, scattered light scattered by a defect DF on the first surface 51. Therefore, the second optical system 20 illuminates the film 50 from the first surface 51 side with the second light L2 reflected by the first surface 51 of the film 50, and receives the second observation light R2 from the first surface 51 side. In this way, the second optical system 20 performs dark-field observation.

[0043] The second observation light R2 transmitted through the objective lens 13 is incident on the mirror 12. The mirror 12 transmits a portion of the second observation light R2. The second observation light R2 transmitted through the mirror 12 is incident on the wavelength selection unit 14.

[0044] The wavelength selection unit 14 reflects the second observation light R2, causing it to enter the lens 25. The lens 25 collects the incident second observation light R2 and guides it to the second detector 26. It is desirable that the second observation light R2 be focused on the second detector 26. This allows the second optical system 20 to be a confocal optical system. The second detector 26 detects the second observation light R2. The second detector 26 may be a TDI or a line sensor.

[0045] The wavelength selection unit 14 may transmit the second observation light R2 and guide it to the second detector 26 via the lens 25. The wavelength selection unit 14 is not limited to a dichroic mirror, and may be a combination of a half mirror and a bandpass filter, as long as it can guide the second observation light R2 to the second detector 26.

[0046] The second detector 26 is connected to the processing device 30 via a communication line including at least one of a wired and wireless line in a state in which information can be transmitted. The second detector 26 outputs the observation results of the dark-field observation by the second optical system 20 to the processing device 30.

[0047] The processing device 30 receives the observation results from the first detector 16 and the second detector 26. Figures 3 and 4 are diagrams illustrating the observation results of bright-field observation and dark-field observation in the inspection device 1 according to the first embodiment, where Figure 3 shows a case where a defect DF exists on the first surface 51 of the film 50, and Figure 4 shows a case where a defect DF exists on the second surface 52 of the film 50.

[0048] If there is no defect DF on the first surface 51 or the second surface 52, the first optical system 10 receives first observation light R1, which is the first light L1 reflected by the film 50. Therefore, if there is no defect DF on the first surface 51 or the second surface 52, the first optical system 10 acquires a white bright-field image. However, as shown in FIG. 3 , if there is a defect DF, such as a foreign substance, on the first surface 51 of the film 50, the first light L1 in bright-field observation is scattered by the defect DF. Specifically, if there is a defect DF on the first surface 51, the first observation light R1 will lack the portion of the reflected light of the first light L1 that is scattered by the defect DF. This allows the first optical system 10 to observe the defect DF, such as a foreign substance, as a portion with reduced brightness in bright-field observation.

[0049] Furthermore, if there is no defect DF on the first surface 51, the second light L2 reflected by the first surface 51 is reflected at the same reflection angle as the angle of incidence. Therefore, the second light L2 reflected by the first surface 51 does not enter the objective lens 13. As a result, the second optical system 20 cannot receive the second observation light R2, which includes the second light L2 reflected by the film 50. If there is no defect DF on the first surface 51, the second optical system 20 acquires a black dark-field image. However, as shown in FIG. 3, if there is a defect DF on the first surface 51 of the film 50, the second light L2 is scattered by the defect DF. Therefore, the second observation light R2 includes the scattered light of the second light L2 scattered by the defect DF. As a result, the second optical system 20 can observe the defect DF, such as a foreign particle, as a brighter area than the surrounding area during dark-field observation.

[0050] 4, if a defect DF such as a foreign particle is present on the second surface 52, the first light L1 in bright-field observation is scattered by the defect DF. Therefore, the first observation light R1 lacks the portion of the reflected light of the first light L1 that is scattered by the defect DF. This allows the first optical system 10 to observe the defect DF such as a foreign particle as a portion with reduced brightness in bright-field observation.

[0051] On the other hand, the second light L2 is reflected by the first surface 51 of the film 50 and is not scattered by the defect DF on the second surface 52. Therefore, as shown in Fig. 4, if there is a defect DF such as a foreign substance on the second surface 52, the second observation light R2 does not contain scattered light that is the second light L2 scattered by the defect DF. As a result, the second optical system 20 does not (cannot) observe the defect DF present on the second surface 52 in dark-field observation.

[0052] The processing device 30 includes a determination unit 31. The determination unit 31 functions as a determination means. The determination unit 31 determines the position of the defect DF in the thickness direction of the film 50 based on a combination of the observation results of bright-field observation using the first optical system 10 and the observation results of dark-field observation using the second optical system 20. That is, the determination unit 31 determines whether the defect DF is a defect DF above the first surface 51 of the film 50 or a defect DF below the first surface 51 based on a combination of the observation results of bright-field observation using the first optical system 10 and the observation results of dark-field observation using the second optical system 20. Here, the first surface side in the thickness direction of the film 50 is defined as the upper side, and the second surface side is defined as the lower side. Defects below the first surface 51 may include defects DF such as holes (pinholes) or dents in the film 50, as well as defects DF caused by foreign matter on the surface of the second surface. Furthermore, the determination unit 31 may determine whether the defect DF in the film 50 is a defect DF on the first surface 51 of the film 50 or a defect DF on the second surface 52 of the film 50, based on a combination of the observation results of bright-field observation using the first optical system 10 and the observation results of dark-field observation using the second optical system 20. Here, the defect DF on the first surface 51 of the film 50 includes a defect DF caused by a foreign substance on the surface of the first surface 51 of the film 50, and the defect DF on the second surface 52 of the film 50 includes a defect DF caused by a foreign substance on the surface of the second surface 52 of the film 50.

[0053] 5 is a diagram illustrating an example of an observation result determined by the determination unit 31 in the inspection apparatus 1 according to the first embodiment. As shown in FIG. 5, when a defect DF is observed in both the observation result using the first optical system 10 (bright-field observation, for example, the wavelength of the first light L1 is 630 nm) and the observation result using the second optical system 20 (dark-field observation, for example, the wavelength of the second light L2 is 405 nm and includes S-polarized light), the determination unit 31 determines that the defect DF is above the first surface 51 of the film 50. On the other hand, when a defect DF is observed in the observation result using the first optical system 10 and no defect DF is observed in the observation result using the second optical system 20, the determination unit 31 determines that the defect DF is below the first surface 51 of the film 50.

[0054] <Variation 1> The determination unit 31 may determine the size and shape of the defect DF based on the observation results from the first optical system 10. Because the optical axis of the first observation light R1 in the first optical system 10 is perpendicular to the first surface 51, the size and shape of the defect DF as viewed from a direction perpendicular to the first surface 51 can be determined. For example, if the size of the observed defect DF is equal to or greater than a predetermined threshold value that allows it to be determined as a foreign substance, or if the shape of the defect DF is equal to or greater than a predetermined shape that allows it to be determined as a foreign substance, the determination unit 31 may determine whether a foreign substance is present on either the first surface 51 or the second surface 52 of the film 50 (Classification 2). Furthermore, if the size (or shape) of the defect DF is equal to or greater than a predetermined second threshold value and it is determined to be a foreign substance on the second surface 52 of the film 50, the determination unit 31 may classify the defect DF as a defect DF that may fall from the second surface 52 of the film 50 onto the sample 40 (Classification 3).

[0055] Fig. 6 is a block diagram illustrating a processing device 30 in the inspection device 1 according to the first embodiment. As shown in Fig. 6, the processing device 30 may further include a control unit 32 and a storage unit 33 in addition to a determination unit 31. The control unit 32 and the storage unit 33 function as a control means and a storage means. The processing device 30 includes an information processing device such as a PC (Personal Computer) or a server.

[0056] <Variation 2> The control unit 32 controls the operations of the determination unit 31 and the storage unit 33 in the processing device 30. The control unit 32 may also control the operations of the first optical system 10 and the second optical system 20. Specifically, for example, in any of the following cases: (i) when it is determined that a defect DF exists on the second surface 52 of the film 50, (ii) when it is determined that the defect DF has a predetermined shape based on the observation results of the first optical system 10, or (iii) when it is determined that a defect DF exists on the second surface 52 of the film 50 and also when it is determined that the defect DF has a predetermined shape based on the observation results of the first optical system 10, the control unit 32 causes the second optical system 20 to perform at least one of a polarization state change, a wavelength change, and an incident angle change.

[0057] In changing the wavelength, the second optical system 20 changes the wavelength of the second light L2 to a wavelength that increases the amount of light that transmits through the film 50. Specifically, for example, the second optical system 20 lengthens the wavelength of the second light L2 to, for example, 600 nm or more and 750 nm or less. Note that the second optical system 20 may change the wavelength of the second light L2 to a wavelength other than 600 nm or more and 750 nm or less, as long as it can increase the amount of light that transmits through the film 50 of the second light L2.

[0058] In changing the angle of incidence, the second optical system 20 changes the angle of incidence of the second light L2 to an angle of incidence that increases the amount of light transmitted through the film 50. Specifically, for example, the second optical system 20 may set the angle of incidence of the second light L2 to be smaller than 60°. In changing the polarization state, for example, the second optical system 20 controls the polarizing member 27 to change the second light L2 to P-polarized light. The second optical system 20 performs dark-field observation in which at least one of the polarization state, wavelength, and angle of incidence is changed. Dark-field observation in which at least one of the polarization state, wavelength, and angle of incidence is changed is called modified dark-field observation.

[0059] The determination unit 31 acquires height information of the defect DF from the results of the modified dark-field observation and classifies the defect DF. Specifically, for example, if the height of the defect DF is equal to or greater than a predetermined first threshold, the determination unit 31 may classify the defect DF as a foreign matter (Classification 2). Also, if the height of the defect DF is equal to or greater than a predetermined second threshold, the determination unit 31 may classify the defect DF as a defect DF that may fall from the second surface 52 of the film 50 onto the sample 40 (Classification 3). Note that if the height of the defect DF is smaller than the predetermined first threshold, the determination unit 31 may classify the defect DF as a defect DF other than a foreign matter, such as a hole (pinhole) or a dent (Classification 1).

[0060] The storage unit 33 stores the observation results. The storage unit 33 may store the observation conditions of the first optical system 10 and the second optical system 20. The storage unit 33 may store height information of the defect DF in association with the classification of the defect DF.

[0061] <Variation 3> The first optical system 10 may observe the pattern surface formed on the photomask by adjusting the focus of the first light L1 in the first optical system 10 on the photomask.

[0062] <Testing method> Next, an inspection method using the inspection device 1 will be described. Fig. 7 is a flowchart illustrating an inspection method using the inspection device 1 according to embodiment 1. In Fig. 7, step S11 of bright-field observation and step S12 of dark-field observation are performed in parallel (simultaneously), but this is not limiting, and step S11 of bright-field observation may be performed before step S12 of dark-field observation, or step S11 of bright-field observation may be performed after step S12 of dark-field observation.

[0063] 7, bright-field observation is performed. Specifically, for example, the control unit 32 may control the first optical system 10 to perform bright-field observation of the film 50 using the first optical system 10. The first optical system 10 illuminates the film 50 with first light L1 that transmits through the film 50 and receives first observation light R1 from the first surface 51 side of the film 50. In step S11 of performing bright-field observation, the first optical system 10 may align the optical axis of the first light L1 perpendicular to the first surface 51 of the film 50.

[0064] Next, as shown in step S12, dark-field observation is performed. Specifically, for example, the control unit 32 may control the second optical system 20 to perform dark-field observation of the film 50 using the second optical system 20. The second optical system 20 illuminates the film 50 from the first surface 51 side with second light L2 reflected from the first surface 51 of the film 50 and receives second observation light R2 from the first surface 51 side. In step S12 for performing dark-field observation, the second optical system 20 may use oblique incidence illumination in which the optical axis of the second light L2 is tilted with respect to the first surface 51 of the film 50. The objective lens 13 that receives the second observation light R2 in the second optical system 20 may be the same as the objective lens 13 that receives the first observation light R1 in the first optical system 10.

[0065] Next, as shown in step S13, the determination unit 31 makes a determination. Specifically, the determination unit 31 determines the position of the defect DF in the thickness direction of the film 50 based on a combination of the observation results of bright-field observation using the first optical system 10 and the observation results of dark-field observation using the second optical system 20. That is, the determination unit 31 determines whether the defect DF is a defect DF above the first surface 51 of the film 50 or a defect DF below the first surface 51 based on a combination of the observation results of bright-field observation using the first optical system 10 and the observation results of dark-field observation using the second optical system 20. The determination unit 31 may also determine whether the defect DF in the film 50 is a defect DF on the first surface 51 or a defect DF on the second surface 52 of the film 50 based on a combination of the observation results of bright-field observation using the first optical system 10 and the observation results of dark-field observation using the second optical system 20. In the determination step S13, if a defect DF is observed in both the observation results using the first optical system 10 and the observation results using the second optical system 20, the determination unit 31 may determine that the defect DF is above the first surface 51 of the film 50. Alternatively, if a defect DF is detected in the observation results using the first optical system 10 and no defect DF is detected in the observation results using the second optical system 20, the determination unit 31 may determine that the defect DF is below the first surface 51 of the film 50.

[0066] The determining unit 31 may determine the shape of the defect DF, including its size, based on the observation results from the first optical system 10, and classify the defect DF.

[0067] Fig. 8 is a flowchart illustrating another inspection method using the inspection device 1 according to embodiment 1. As shown in Fig. 8, the method may further include step S14 of modified dark-field observation by changing the polarization state, wavelength, and incident angle, and step S15 of determining defects DF.

[0068] As shown in step S14, when it is determined that a defect DF exists on the second surface 52 of the film 50 and the defect DF is determined to have a predetermined shape based on the observation results of the first optical system 10, the control unit 32 controls the second optical system 20 to perform modified dark-field observation in which at least one of a polarization state change, a wavelength change, and an incident angle change is performed. Here, the wavelength change in the second optical system 20 refers to changing the wavelength of the second light L2 to a wavelength that increases the amount of light transmitted through the film 50. The incident angle change refers to changing the incident angle of the second light L2 to an incident angle that increases the amount of light transmitted through the film 50. The polarization state change refers to changing the polarization state of the second light L2 to a polarization state that increases the amount of light transmitted through the film 50.

[0069] Next, as shown in step S15, the height information and the classification of the defect are determined. Specifically, the determination unit 31 acquires height information of the defect from modified dark-field observation in which at least one of a polarization state change, a wavelength change, and an incident angle change is performed in the second optical system 20, and classifies the defect DF.

[0070] Next, the effects of this embodiment will be described. The determination unit 31 of this embodiment determines whether there are defects on the first surface 51 and the second surface 52 of the film 50 based on a combination of the observation results of bright-field observation and dark-field observation. Specifically, for example, by combining bright-field observation (normal incidence) that can detect defects on the front and back surfaces of the pellicle with dark-field observation (oblique incidence) that detects defects only on the front surface, defects such as foreign matter on the pellicle and front / back separation detection are performed. This allows the inspection device 1 to determine defects in the film 50 with high accuracy.

[0071] The first optical system 10 sets the optical axis of the first light L1 perpendicular to the first surface 51. Therefore, the inspection device 1 can determine the shape, including the size, of the defect DF using the first light L1 in bright-field observation. Specifically, the diameter of the foreign matter can be calculated from the defect detected in bright-field observation.

[0072] It is believed that defects such as foreign matter of a predetermined size and shape adhering to a pellicle can cause membrane rupture. In this embodiment, defects of a predetermined size and shape can be determined, thereby preventing damage.

[0073] Furthermore, foreign matter of a predetermined size and shape adhering to the pellicle may fall onto the photomask due to a rise in temperature, etc. In this embodiment, defects of a predetermined size and shape can be determined, and therefore, falling onto the photomask can be prevented.

[0074] The second optical system 20 also uses oblique incidence illumination in which the optical axis of the second light L2 is tilted relative to the first surface 51. Additionally, the second optical system 20 uses oblique incidence illumination with short wavelength visible light and S-polarized light. Therefore, the second optical system 20 can perform dark-field observation and detect only defects on the surface of the pellicle. Therefore, it is possible to distinguish whether the defect DF exists on the first surface 51 or the second surface 52 of the film 50.

[0075] If it is determined that a defect DF exists on the second surface 52 of the film 50, and if the defect DF is determined to have a predetermined shape based on the observation results of the first optical system 10, the second optical system 20 performs modified dark-field observation by changing at least one of the wavelength of the second light L2 and the angle of incidence of the second light L2. This allows the determination unit 31 to acquire height information of the defect DF and classify the defect DF. Therefore, the inspection device 1 can determine the classification of the defect in the film 50 with high accuracy.

[0076] By using different wavelengths for bright-field and dark-field observations, bright-field and dark-field observations can be performed simultaneously with a single scan, thereby shortening the observation time.

[0077] <Embodiment 2> Next, an inspection device and an inspection method according to embodiment 2 will be described. In this embodiment, oblique incidence illumination in the second optical system 20 for dark-field observation is performed using optical paths from multiple directions arranged in a ring shape around the objective lens 13. Then, defects DF such as pinholes are determined based on the observation results of the dark-field observation.

[0078] Fig. 9 is a configuration diagram illustrating an inspection device 2 according to embodiment 2. Fig. 10 is a cross-sectional view illustrating the arrangement of the objective lens 13 and the mirror 22 in the second optical system 20a in the inspection device 2 according to embodiment 2, showing a cross section taken along line AA in Fig. 9. Fig. 11 is a cross-sectional view illustrating the arrangement of the objective lens 13 and the mirror 22 in the second optical system 20b in the inspection device 2 according to embodiment 2. Fig. 12 is a diagram illustrating oblique incidence illumination in the second optical system 20c in the inspection device 2 according to embodiment 2.

[0079] As shown in FIG. 9 , in the inspection device 2 of this embodiment, the second optical system 20a uses oblique incidence illumination in which the optical axis of the second light L2 is tilted from multiple directions relative to the first surface 51. The multiple directions include, for example, directions from around the objective lens 13 toward the irradiation point of the second light L2. That is, the multiple directions include radial directions centered on the irradiation point where the second light L2 irradiates the first surface 51 when viewed from the Z-axis direction. As shown in FIG. 10 , the second optical system 20a may use multiple mirrors 22 disposed at multiple positions in a circular ring shape surrounding the objective lens 13 that receives the second observation light R2. The second optical system 20a provides oblique incidence illumination to the irradiation point from multiple optical paths via the multiple mirrors 22. Note that oblique incidence illumination may be achieved from multiple optical paths by using a ring-shaped mirror 22. Alternatively, oblique incidence illumination may be achieved from multiple optical paths by using multiple optical fibers arranged to surround the objective lens 13 in addition to or instead of the mirror 22. 11, the oblique incidence illumination does not have to be ring-shaped as long as it can illuminate the film 50 from at least multiple directions. The angle of incidence of the oblique incidence illumination with respect to the first surface 51 of the film 50 may be a constant angle in all directions, or multiple angles of incidence may be used as shown in FIG. 12. For example, the angle of incidence of the oblique incidence illumination may be an angle θ1 and an angle θ2 different from the angle θ1.

[0080] FIG. 13 illustrates the results of dark-field observation using the second optical system 20a in the inspection device 2 according to the second embodiment. As shown in FIG. 13, in the case of oblique incidence illumination, in which the second light L2 is incident from one direction (1WAY), the illumination area at the edge of the pinhole HL is small, making it difficult to detect the pinhole HL. On the other hand, in the case of oblique incidence illumination, in which the second light L2 is incident from multiple ring-shaped directions (RING), the illumination area at the pinhole HL extends to the entire peripheral edge of the pinhole HL, making it possible to detect features unique to the pinhole HL, including scattered light from the edge of the pinhole HL. The pinhole HL includes a hole that penetrates from the first surface 51 to the second surface 52 of the film 50. In addition, in the case of a film 50 such as a pellicle, depressions may be formed on the surface of the film 50. The depressions described below include depressions formed on the first surface 51 of the film 50.

[0081] FIG. 14 illustrates the results of bright-field and dark-field observations performed by the inspection device 2 according to the second embodiment, showing the presence of a pinhole HL in the film 50. As shown in the right diagram of FIG. 14, when a pinhole HL is formed in the film 50, the first light L1 in bright-field observation passes through the pinhole HL. Therefore, the first observation light R1 lacks the portion of the reflected light of the first light L1 that passes through the pinhole HL. This allows the first optical system 10 to observe the pinhole HL as a portion with reduced brightness in bright-field observation. In bright-field observation, the central brightness of the pinhole HL is equal to or less than a predetermined threshold. The threshold may be set in advance as the brightness of the pinhole HL, for example.

[0082] Although not shown, if a recess is formed on the first surface 51, the first light L1 in bright-field observation enters the recess. A portion of the first light L1 that enters the recess is scattered by the wall and bottom surfaces of the recess. As a result, a portion of the first light L1 that enters the recess is not focused as reflected light by the objective lens 13. However, another portion of the first light L1 that enters the recess is reflected by the bottom surface of the recess and focused as reflected light by the objective lens 13. Therefore, the first observation light R1 includes the reflected light of the first light L1 that is reflected by the bottom surface of the recess, but lacks the portion scattered by the recess. As a result, the first optical system 10 can observe the recess in bright-field observation as a portion with reduced brightness that exceeds a predetermined threshold. Therefore, in bright-field observation, the central brightness of the recess exceeds the predetermined threshold but is low.

[0083] As shown in the left diagram of FIG. 14, the second light L2 in dark-field observation with oblique incidence illumination is scattered by the edge of the pinhole HL. In this embodiment, since the second light L2 is incident from multiple directions with oblique incidence illumination, the second light L2 is scattered by the edge of the pinhole HL all around. Therefore, the second observation light R2 includes scattered light resulting from the second light L1 being scattered by the edge of the pinhole HL all around. This allows the second optical system 20a to observe the edge of the pinhole HL as a high-brightness area in dark-field observation.

[0084] Furthermore, although not shown, if a depression is formed on the first surface 51, the second light L2 in dark-field observation using oblique incidence illumination is scattered by the edge of the depression. In this embodiment, the second light L2 is incident from multiple directions with oblique incidence illumination, so the second light L2 is scattered by the edge of the entire periphery of the depression. Therefore, the second observation light R2 includes scattered light resulting from the second light L1 being scattered by the edge of the entire periphery of the depression. Therefore, the second optical system 20a can observe the edge of the depression as a high-brightness area in dark-field observation.

[0085] 15 and 16 are graphs illustrating the luminance in the observation results of bright-field observation and dark-field observation in the inspection device 2 according to embodiment 2, where the horizontal axis indicates the position on the film 50 along the X-axis direction and the vertical axis indicates the luminance. As shown in Fig. 15 and 16, when a ring-shaped defect is observed in dark-field observation, it is possible to determine whether the defect formed in the film 50 is a pinhole HL or a dent based on the central luminance of the defect in bright-field observation.

[0086] 15 and 16, in the case of bright-field observation of a film 50 in which a pinhole HL and a depression are formed, the change in brightness due to the edges of the pinhole HL and the depression is gradual, making it difficult to identify the edges of the pinhole HL and the depression. In contrast, in the case of dark-field observation, the change in brightness due to the edges of the pinhole HL and the depression is steep. Therefore, it is possible to identify the edges of the pinhole HL and the depression. This makes it possible to determine the diameter size of the pinhole HL and the depression on the first surface 51.

[0087] 17 is a diagram illustrating the observation results of bright-field observation and dark-field observation in the inspection device 2 according to the second embodiment, showing a case where particles are present on the first surface 51 of the film 50. As shown in FIG. 17, when particles are present on the first surface 51 of the film 50, the first light L1 in bright-field observation is scattered by the particles. This allows the first optical system 10 to observe the particles as areas with reduced brightness in bright-field observation.

[0088] On the other hand, the second light L2 in dark-field observation with oblique incidence illumination is scattered by the particles. As a result, the second optical system 20 can observe the particles as areas with higher brightness than the surrounding area in dark-field observation. In this embodiment, the second light L2 is incident from multiple directions with oblique incidence illumination, so the brightness of the scattered light by the particles can be made higher than the brightness in FIG. 3, thereby improving detection accuracy.

[0089] 18 is a diagram illustrating an example of an observation result determined by the determination unit 31 in the inspection apparatus 2 according to embodiment 2. As shown in Fig. 18, when a defect DF is observed in both the bright-field observation result using the first optical system 10 and the dark-field observation result using the second optical system 20 with oblique incidence illumination from multiple directions, and a defect that is not ring-shaped is observed in the dark-field observation, the determination unit 31 determines that the defect DF is located above the first surface 51 of the film 50. In this case, the determination unit 31 determines the diameter size of the defect on the first surface 51 by bright-field observation.

[0090] On the other hand, if a defect DF is observed in the observation results using the first optical system 10 and no defect DF is observed in the observation results using the second optical system 20, the determination unit 31 determines that the defect DF is below the first surface 51 of the film 50. The determination unit 31 determines the size of the diameter of the defect projected onto the first surface 51 by bright-field observation. Classifications 2 and 3 are as described above.

[0091] When a defect DF is observed in both the results of bright-field observation using the first optical system 10 and the results of dark-field observation using oblique incidence illumination from multiple directions using the second optical system 20, and when a ring-shaped defect is observed in the dark-field observation and the central luminance of the defect in the bright-field observation is equal to or less than a threshold, the determination unit 31 determines that the defect is a pinhole HL formed in the film 50. In this case, the determination unit 31 determines the size of the pinhole HL based on the bright-field observation and the dark-field observation. That is, the determination unit 31 determines that the defect DF is a pinhole HL based on the results of the bright-field observation and the dark-field observation, and determines the diameter size of the pinhole HL on the first surface 51 based on the results of the dark-field observation.

[0092] When a defect DF is observed in both the results of bright-field observation using the first optical system 10 and the results of dark-field observation using oblique incidence illumination from multiple directions using the second optical system 20, and when a ring-shaped defect is observed in the dark-field observation and the central luminance of the defect in the bright-field observation exceeds a threshold, the determination unit 31 determines that the defect is a dent formed in the film 50. In this case, the determination unit 31 determines the size of the dent based on the bright-field observation and the dark-field observation. That is, the determination unit 31 determines that the defect DF is a dent based on the results of the bright-field observation and the dark-field observation, and determines the diameter size of the dent on the first surface 51 based on the results of the dark-field observation.

[0093] The determination unit 31 may determine the classification of the defect DF based on the observation results of dark-field observation using oblique incidence illumination from multiple directions with the second optical system 20. That is, when a defect DF is observed with the dark-field observation with the second optical system 20, the determination unit 31 determines that the defect is a foreign substance, a pinhole HL, or a dent on the first surface 51. When a defect DF is not observed with the dark-field observation with the second optical system 20, the determination unit 31 determines that there is a foreign substance below the first surface 51, or that there is no defect. When a defect DF that is not ring-shaped is observed with the dark-field observation with the second optical system 20, the determination unit 31 determines that the defect is a foreign substance on the first surface 51. When a ring-shaped defect DF is observed with the dark-field observation with the second optical system 20, the determination unit 31 determines that the defect is a pinhole HL or a dent. Furthermore, when a ring-shaped defect DF is observed in the results of dark-field observation using the second optical system 20, the judgment unit 31 judges the defect to be a pinhole HL if the central brightness of the defect is below a threshold value in the results of bright-field observation using the first optical system 10, and judges the defect to be a dent if the central brightness of the defect exceeds the threshold value.

[0094] When the defect DF is classified as a foreign substance, the determination unit 31 determines the size of the foreign substance based on the observation results of bright-field observation using the first optical system 10. When the defect is classified as a pinhole HL or a dent, the determination unit 31 determines the size of the pinhole HL or the dent based on the observation results of bright-field observation using the first optical system 10 and the observation results of dark-field observation using the second optical system 20.

[0095] Next, the inspection method will be described. In the inspection method of this embodiment, in step S12 for performing dark-field observation, the second optical system 20 uses oblique incidence illumination in which the optical axis of the second light L2 is tilted from multiple directions with respect to the first surface 51. In step S12 for performing dark-field observation, the second optical system 20 may also provide oblique incidence illumination from multiple optical paths provided at multiple positions that surround the periphery of the objective lens 13 that receives the second observation light R2 in an annular shape.

[0096] In the determining step S13, the classification of the defect DF is determined based on the observation results of the dark-field observation using the second optical system 20. Here, the classification of the defect DF includes pinholes HL and dents. In the determining step S13, the sizes of the pinholes HL and dents may be determined based on the observation results of the bright-field observation using the first optical system 10 and the observation results of the dark-field observation using the second optical system 20.

[0097] In the determination step S13, if the defect DF is classified as a foreign substance, the size of the foreign substance is determined based on the observation results of bright-field observation using the first optical system 10. If the defect DF is classified as a pinhole or a dent, the sizes of the pinhole HL and the dent may be determined based on the observation results of bright-field observation using the first optical system 10 and the observation results of dark-field observation using the second optical system 20.

[0098] According to this embodiment, pinholes HL in the film 50 and recesses on the first surface 51 of the film 50 can be observed as ring-shaped scattered light by dark-field observation using the second optical system 20. In this case, the pinholes HL and recesses can be distinguished by combining this with bright-field observation using the first optical system 10. Furthermore, the inspection device 2 of this embodiment can accurately measure the sizes of the pinholes HL and recesses on the first surface 51.

[0099] <Embodiment 3> Next, an inspection device and an inspection method according to embodiment 3 will be described. In the inspection device 1 of embodiment 1, it was assumed that the determination unit 31 determines whether the position of the defect DF in the film 50 is above the first surface 51 of the film 50 or below the first surface 51, based on a combination of the observation results of bright-field observation with the first optical system 10 and the observation results of dark-field observation with the second optical system 20. In this embodiment, the size of the defect DF is determined without relying on such a determination.

[0100] Specifically, the inspection device includes a first optical system 10, a second optical system 20, and a determination unit 31. The first optical system 10 illuminates the film 50 with a first light L1 that transmits through the film 50 and receives a first observation light R1 from the first surface 51 side of the film 50. The second optical system illuminates the film 50 from the first surface 51 side with a second light L2 that reflects off the first surface 51 of the film 50 and receives a second observation light R2 from the first surface 51 side. The second optical system 20 uses oblique incidence illumination in which the optical axis of the second light L2 is tilted from multiple directions with respect to the first surface 51. The second optical system 20 may provide oblique incidence illumination from multiple optical paths provided at multiple positions that surround the periphery of an objective lens 13 that receives the second observation light R2 in a circular ring shape.

[0101] The determination unit 31 determines the size of a concave defect formed in the film 50 on the first surface 51 based on a combination of the observation results of bright-field observation using the first optical system 10 and the observation results of dark-field observation using the second optical system 20. Concave defects include pinholes HL and dents. If the defect is classified (type) as a foreign substance, the determination unit 31 may determine the size of the foreign substance based on the observation results of bright-field observation using the first optical system 10, and if the defect is classified (type) as a concave defect, the determination unit 31 may determine the size of the concave defect based on the observation results of bright-field observation using the first optical system 10 and the observation results of dark-field observation using the second optical system 20. Even with this configuration, the size of the concave defect on the first surface 51 can be measured with high accuracy. The determination unit 31 may also determine the classification of a concave defect formed in the film 50 based on a combination of the observation results of bright-field observation using the first optical system 10 and the observation results of dark-field observation using the second optical system 20. That is, when a ring-shaped defect DF is observed in the results of dark-field observation using the second optical system 20, the judgment unit 31 detects a depression defect including at least one of a pinhole HL and a dent, and when the results of bright-field observation using the first optical system 10 show that the central luminance of the defect is equal to or less than a threshold, the judgment unit 31 judges that the depression defect is a pinhole HL, and when the central luminance of the defect exceeds the threshold, the judgment unit 31 judges that the depression defect is a dent.

[0102] The inspection method of this embodiment includes step S11 for bright-field observation, step S12 for dark-field observation, and step S13 for judgment. In step S11 for bright-field observation, the film 50 is illuminated with first light L1 that transmits through the film 50, and first observation light R1 is received from the first surface 51 side of the film 50. In step S12 for dark-field observation, the film 50 is illuminated from the first surface 51 side with second light L2 that reflects off the first surface 51 of the film 50, and second observation light R2 is received from the first surface 51 side. The second optical system 20 uses oblique incidence illumination in which the optical axis of the second light L2 is tilted from multiple directions with respect to the first surface 51. The second optical system 20 provides oblique incidence illumination from multiple optical paths provided at multiple positions that surround the periphery of the objective lens 13, which receives the second observation light L2.

[0103] In determining step S13, the determining unit 31 determines the size of the depressed defect formed in the film 50 on the first surface 51 based on a combination of the observation results of the bright-field observation using the first optical system 10 and the dark-field observation using the second optical system 20. In the determining step, if the defect DF is classified as a foreign matter, the size of the foreign matter is determined based on the observation results of the bright-field observation using the first optical system 10. If the defect DF is classified as a depressed defect, the size of the depressed defect is determined based on the observation results of the bright-field observation using the first optical system 10 and the dark-field observation using the second optical system 20. In determining step S13, the classification of the depressed defect formed in the film 50 may be determined based on a combination of the observation results of the bright-field observation using the first optical system 10 and the dark-field observation using the second optical system 20.

[0104] Although the embodiments of the present disclosure have been described above, the present disclosure includes appropriate modifications that do not impair the objects and advantages thereof, and is not limited to the above-described embodiments. Furthermore, appropriate omissions and combinations of the configurations of Embodiments 1 to 3 are also within the scope of the technical concept of the present disclosure. Furthermore, the following configurations are also within the scope of the technical concept of the embodiments.

[0105] (Appendix 1) performing bright-field observation using a first optical system that illuminates the film with first light that transmits through the film and receives the first observation light from a first surface side of the film; a step of illuminating the film from the first surface side with second light reflected by the first surface of the film and performing dark-field observation using a second optical system that receives second observation light from the first surface side; a step of determining, based on a combination of the observation results of the bright-field observation using the first optical system and the observation results of the dark-field observation using the second optical system, whether the position of the defect in the film is above the first surface of the film or below the first surface, when the first surface side in the thickness direction of the film is defined as an upper side and the second surface side opposite to the first surface is defined as a lower side; An inspection method comprising: (Appendix 2) In the determining step, When the defect is detected in both the observation result using the first optical system and the observation result using the second optical system, the defect is determined to be located above the first surface; If the defect is detected in the observation result using the first optical system and the defect is not detected in the observation result using the second optical system, the defect is determined to be below the first surface. Testing method is in Appendix 1. (Appendix 3) In the determining step, When the defect is detected in both the observation result using the first optical system and the observation result using the second optical system, the defect is determined to be caused by a foreign substance on the surface of the first surface; When the defect is detected in the observation result using the first optical system and the defect is not detected in the observation result using the second optical system, it is determined that the defect is caused by a foreign substance on the surface of the second surface. (Appendix 4) In the step of performing bright-field observation, the first optical system makes the optical axis of the first light perpendicular to the first surface; In the step of performing dark-field observation, the second optical system uses oblique incidence illumination in which the optical axis of the second light is tilted with respect to the first surface, an objective lens in the second optical system that receives the second observation light is common to the objective lens in the first optical system that receives the first observation light; Testing method described in Appendix 1. (Appendix 5) In the step of performing bright-field observation, the first optical system illuminates the film from the first surface side with the first light; the objective lens focuses the first light of the first optical system onto the film; Testing method described in Appendix 4. (Appendix 6) In the step of performing bright-field observation, the first light in the first optical system includes a wavelength of 600 nm or more and 750 nm or less, In the step of performing dark-field observation, the second light in the second optical system includes a wavelength of 350 nm or more and 550 nm or less, the incident angle of the second light in the second optical system is greater than or equal to 60° and less than or equal to 85°, Testing method described in Appendix 1. (Appendix 7) In the determining step, determining a shape including a size of the defect based on the observation result by the first optical system; determining a position of the defect in a thickness direction of the film when the shape of the defect is a predetermined shape; Testing method described in Appendix 1. (Appendix 8) performing modified dark-field observation in the second optical system by performing at least one of a polarization state change to change the polarization state of the second light to a polarization state that increases the amount of light that transmits through the film, a wavelength change to change the wavelength of the second light to a wavelength that increases the amount of light that transmits through the film, and an incident angle change to change the incident angle of the second light to an incident angle that increases the amount of light that transmits through the film; obtaining height information of the defect from the result of the modified dark-field observation and classifying the defect; Furthermore, Testing method described in Appendix 1. (Appendix 9) the membrane comprises a pellicle attached to a photomask; Testing method described in Appendix 4. (Appendix 10) the depth of focus of the objective lens is smaller than the distance between the photomask and the pellicle; Testing method described in Appendix 9. (Appendix 11) the membrane comprises a pellicle attached to a photomask; The method further includes a step of observing a pattern surface formed on the photomask using the first optical system. Testing method described in Appendix 5. (Appendix 12) The photomask includes a photomask for EUV exposure. Testing method described in Appendix 9. (Appendix 13) In the step of performing dark-field observation, the second optical system uses oblique incidence illumination in which the optical axis of the second light is tilted from a plurality of directions with respect to the first surface, In the determining step, determining a classification of the defect based on the observation result of the dark-field observation using the second optical system; The defect classification includes pinholes. Testing method described in Appendix 1. (Appendix 14) In the step of performing dark-field observation, the second optical system illuminates the second observation light obliquely from a plurality of optical paths provided at a plurality of positions surrounding the periphery of the objective lens that receives the second observation light, The test method described in Appendix 13. (Appendix 15) In the determining step, determining the size of the pinhole based on the observation result of the bright-field observation using the first optical system and the observation result of the dark-field observation using the second optical system; The test method described in Appendix 13. (Appendix 16) In the determining step, If the classification of the defect is a foreign object, a size of the foreign object is determined based on the observation result of the bright-field observation using the first optical system; If the classification of the defect is the pinhole, determining the size of the pinhole based on the observation result of the bright-field observation using the first optical system and the observation result of the dark-field observation using the second optical system. The test method described in Appendix 15. (Appendix A1) a first optical system that illuminates the film with first light that passes through the film and receives first observation light from a first surface side of the film; a second optical system that illuminates the film from the first surface side with second light reflected by the first surface of the film and receives second observation light from the first surface side; a determination unit that determines the size of a depression defect, including at least one of a pinhole and a dent, formed in the film on the first surface based on a combination of an observation result of bright-field observation using the first optical system and an observation result of dark-field observation using the second optical system; Equipped with the second optical system uses oblique incidence illumination in which the optical axis of the second light is tilted from a plurality of directions with respect to the first surface, Inspection equipment. (Appendix A2) the second optical system illuminates the second observation light obliquely from a plurality of optical paths provided at a plurality of positions surrounding the periphery of the objective lens that receives the second observation light, The inspection device described in Appendix A1. (Appendix A3) The determination unit classifying the defect as a foreign substance or a depression defect based on the observation result of the dark-field observation using the second optical system; If the classification of the defect is a foreign object, a size of the foreign object is determined based on the observation result of the bright-field observation using the first optical system; If the classification of the defect is the depression defect, the size of the depression defect is determined based on the observation result of the bright-field observation using the first optical system and the observation result of the dark-field observation using the second optical system. Inspection equipment as described in Appendix A1. (Appendix B1) performing bright-field observation using a first optical system that illuminates the film with first light that transmits through the film and receives the first observation light from a first surface side of the film; a step of illuminating the film from the first surface side with second light reflected by the first surface of the film and performing dark-field observation using a second optical system that receives second observation light from the first surface side; a step of determining, by a determination unit, a size of a depression defect, including at least one of a pinhole and a dent, formed in the film on the first surface based on a combination of an observation result of the bright-field observation using the first optical system and an observation result of the dark-field observation using the second optical system; Equipped with In the step of performing dark-field observation, the second optical system uses oblique incidence illumination in which the optical axis of the second light is tilted from a plurality of directions with respect to the first surface; Testing method. (Appendix B2) In the step of performing dark-field observation, the second optical system illuminates the second observation light obliquely from a plurality of optical paths provided at a plurality of positions surrounding the periphery of the objective lens that receives the second observation light, Testing method described in Appendix B1. (Appendix B3) In the determining step, classifying the defect as a foreign substance or a depression defect based on the observation result of the dark-field observation using the second optical system; If the classification of the defect is a foreign object, a size of the foreign object is determined based on the observation result of the bright-field observation using the first optical system; When the classification of the defect is the depression defect, the size of the depression defect is determined based on the observation result of the bright-field observation using the first optical system and the observation result of the dark-field observation using the second optical system. Testing method described in Appendix B1. (Appendix C1) a first optical system that illuminates the film with first light that passes through the film and receives first observation light from a first surface side of the film; a second optical system that illuminates the film from the first surface side with second light reflected by the first surface of the film and receives second observation light from the first surface side; a determination unit that determines whether a depression defect including at least one of a pinhole and a dent formed in the film has been detected based on an observation result of the dark-field observation using the second optical system, and classifies the depression defect as either the pinhole or the dent based on the observation result of the bright-field observation using the first optical system; Equipped with the second optical system uses oblique incidence illumination in which the optical axis of the second light is tilted from a plurality of directions with respect to the first surface, Inspection equipment. (Appendix C2) the second optical system illuminates the second observation light obliquely from a plurality of optical paths provided at a plurality of positions surrounding the periphery of the objective lens that receives the second observation light, 1. An inspection device as described in Appendix C1. (Appendix D1) performing bright-field observation using a first optical system that illuminates the film with first light that transmits through the film and receives the first observation light from a first surface side of the film; a step of illuminating the film from the first surface side with second light reflected by the first surface of the film and performing dark-field observation using a second optical system that receives second observation light from the first surface side; a determination step of determining whether a depression defect including at least one of a pinhole and a dent formed in the film has been detected based on an observation result of the bright-field observation using the first optical system, and classifying the depression defect as either the pinhole or the dent based on an observation result of the dark-field observation using the second optical system; Equipped with In the step of performing dark-field observation, the second optical system uses oblique incidence illumination in which the optical axis of the second light is tilted from a plurality of directions with respect to the first surface; Testing method. (Appendix D2) In the step of performing dark-field observation, the second optical system illuminates the second observation light obliquely from a plurality of optical paths provided at a plurality of positions surrounding the periphery of the objective lens that receives the second observation light, Testing method described in Appendix D1. [Explanation of symbols]

[0106] 1, 2 Inspection equipment 10 First optical system 11 Light source 12. Mirror 13 Objective Lens 14 Wavelength selection section 15 Lenses 16 First detector 20, 20a, 20b, 20c 2nd optical system 21 Light source 22 Mirror 25 lenses 26 Second detector 27 Polarizing element 30 Processing equipment 31 Judgment section 32 Control section 33 Storage section 40 samples 50 membrane 51 Page 1 52 2nd page DF Defect HL Pinhole L1 1st light L2 2nd light R1 First observation beam R2 Second observation beam

Claims

1. a first optical system that illuminates the film with first light that passes through the film and receives first observation light from a first surface side of the film; a second optical system that illuminates the film from the first surface side with second light reflected by the first surface of the film and receives second observation light from the first surface side; a determination unit that determines whether a position of a defect in the film is above the first surface of the film or below the first surface, based on a combination of the observation results of bright-field observation using the first optical system and the observation results of dark-field observation using the second optical system, with the first surface side in the thickness direction of the film defined as an upper side and a second surface side opposite to the first surface defined as a lower side; An inspection device equipped with:

2. The determination unit When the defect is detected in both the observation result using the first optical system and the observation result using the second optical system, the defect is determined to be located above the first surface; If the defect is detected in the observation result using the first optical system and the defect is not detected in the observation result using the second optical system, the defect is determined to be below the first surface.

10. The inspection device according to claim 1.

3. The determination unit When the defect is detected in both the observation result using the first optical system and the observation result using the second optical system, the defect is determined to be caused by a foreign substance on the surface of the first surface; If the defect is detected in the observation result using the first optical system and the defect is not detected in the observation result using the second optical system, the defect is determined to be caused by a foreign substance on the surface of the second surface.

10. The inspection device according to claim 1.

4. the first optical system makes the optical axis of the first light perpendicular to the first surface; the second optical system uses oblique incidence illumination in which the optical axis of the second light is inclined with respect to the first surface, an objective lens in the second optical system that receives the second observation light is common to the objective lens in the first optical system that receives the first observation light; The inspection device according to claim 1 .

5. the first optical system illuminates the film from the first surface side with the first light; the objective lens focuses the first light of the first optical system onto the film; The inspection device according to claim 4.

6. the first light in the first optical system includes a wavelength of 600 nm or more and 750 nm or less, the second light in the second optical system includes a wavelength of 350 nm or more and 550 nm or less, an incident angle of the second light in the second optical system is greater than or equal to 60° and less than or equal to 85°; The inspection device according to claim 1 .

7. The determination unit determining a shape of the defect including its size based on the observation result by the first optical system; determining a position of the defect in a thickness direction of the film when the shape of the defect is a predetermined shape; The inspection device according to claim 1 .

8. the second optical system performs modified dark-field observation by performing at least one of a polarization state change to change the polarization state of the second light to a polarization state that increases the amount of light that transmits through the film, a wavelength change to change the wavelength of the second light to a wavelength that increases the amount of light that transmits through the film, and an incident angle change to change the incident angle of the second light to an incident angle that increases the amount of light that transmits through the film, the determination unit acquires height information of the defect from a result of the modified dark-field observation and classifies the defect. The inspection device according to claim 1 .

9. the membrane comprises a pellicle attached to a photomask; The inspection device according to claim 4.

10. the depth of focus of the objective lens is smaller than the distance between the photomask and the pellicle; The inspection device according to claim 9.

11. the membrane comprises a pellicle attached to a photomask; the first optical system observes a pattern surface formed on the photomask; The inspection device according to claim 5 .

12. The photomask includes a photomask for EUV exposure. The inspection device according to claim 9.

13. performing bright-field observation using a first optical system that illuminates the film with first light that transmits through the film and receives the first observation light from a first surface side of the film; a step of illuminating the film from the first surface side with second light reflected by the first surface of the film and performing dark-field observation using a second optical system that receives second observation light from the first surface side; a step of determining, based on a combination of the observation results of the bright-field observation using the first optical system and the observation results of the dark-field observation using the second optical system, whether the position of the defect in the film is above the first surface of the film or below the first surface, when the first surface side in the thickness direction of the film is defined as an upper side and the second surface side opposite to the first surface is defined as a lower side; An inspection method comprising:

14. the second optical system uses oblique incidence illumination in which the optical axis of the second light is tilted from a plurality of directions with respect to the first surface, the determining unit determines a classification of the defect based on the observation result of the dark-field observation using the second optical system; The defect classification includes pinholes. The inspection device according to claim 1 .

15. the second optical system illuminates the second observation light obliquely from a plurality of optical paths provided at a plurality of positions surrounding the periphery of an objective lens that receives the second observation light, The inspection device according to claim 14.

16. the determining unit determines the size of the pinhole based on the observation result of the bright-field observation using the first optical system and the observation result of the dark-field observation using the second optical system. The inspection device according to claim 14.

17. The determination unit If the classification of the defect is a foreign object, a size of the foreign object is determined based on the observation result of the bright field observation using the first optical system; If the classification of the defect is the pinhole, the size of the pinhole is determined based on the observation result of the bright-field observation using the first optical system and the observation result of the dark-field observation using the second optical system.

17. The inspection device according to claim 16.

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