Inspection apparatus and inspection method

Abstract

An inspection apparatus and method are provided for accurately determining defects in a film. The inspection apparatus 1 of the present invention comprises: a first optical system 10, which illuminates the film 50 with a first light ray L1 that penetrates the film 50 and receives a first observation light ray R1 from the side of the first surface 51 of the film 50; a second optical system 20, which illuminates the film 50 from the side of the first surface 51 with a second light ray L2 reflected at the first surface 51 of the film 50 and receives a second observation light ray R2 from the side of the first surface 51; and a determination unit 31, which determines, based on a combination of the observation results from bright-field observation in the first optical system 10 and dark-field observation in the second optical system 20, whether the position of a defect DF in the film 50 is a defect DF located above or below the first surface 51 of the film 50.

Description

[Technical Field]

[0001] This invention relates to an inspection device and an inspection method. [Previous Technology]

[0002] Patent Document 1 discloses an inspection method using a dark-field illumination system, which is capable of determining whether a foreign object on a pellicle is on the surface of the pellicle or on the back side of the pellicle. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-258241. [Summary of the Invention]

[0004] [Problem to be solved by the invention] It is desirable to determine with higher accuracy whether a defect in a film such as a film is a defect on the surface of the film or a defect on the back side of the film.

[0005] This invention was created to solve the problems described above, and aims to provide an inspection device and method for determining membrane defects with high accuracy.

[0006] [Means for Solving the Problem] The inspection apparatus of the present invention comprises: a first optical system that illuminates the film with a first light penetrating the film and receives a 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 reflected from the first surface side of the film and receives a second observation light from the first surface side of the film; and a determination unit that, based on a combination of observation results from bright-field observation in the first optical system and dark-field observation in the second optical system, determines whether the location of a defect in the film, when the first surface side in the thickness direction of the film is taken as the upper side and the second surface side, which is the opposite side of the first surface, is taken as the lower side, is either a defect higher than the first surface of the film or a defect lower than the first surface of the film.

[0007] In the aforementioned inspection device, the aforementioned determination unit may determine that the aforementioned defect is located above the aforementioned first surface when both the aforementioned observation results in the aforementioned first optical system and the aforementioned observation results in the aforementioned second optical system detect the aforementioned defect; or the aforementioned determination unit may determine that the aforementioned defect is located below the aforementioned first surface when the aforementioned defect is detected by the aforementioned observation results in the aforementioned first optical system but not by the aforementioned observation results in the aforementioned second optical system.

[0008] In the aforementioned inspection device, the aforementioned determination unit may determine that the aforementioned defect is caused by a foreign object on the surface of the first surface when both the aforementioned observation results in the first optical system and the aforementioned observation results in the second optical system detect the aforementioned defect; or the aforementioned determination unit may determine that the aforementioned defect is caused by a foreign object on the surface of the second surface when the aforementioned defect is detected by the aforementioned observation results in the first optical system but not by the aforementioned observation results in the second optical system.

[0009] In the aforementioned inspection device, the aforementioned first optical system may be configured such that the optical axis of the aforementioned first light ray is perpendicular to the aforementioned first surface; the aforementioned second optical system uses oblique incident illumination, and the aforementioned oblique incident illumination is configured such that the optical axis of the aforementioned second light ray is inclined relative to the aforementioned first surface; the objective lens used in the aforementioned second optical system to receive the aforementioned second observation light ray is common to the aforementioned objective lens used in the aforementioned first optical system to receive the aforementioned first observation light ray.

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

[0011] In the aforementioned inspection device, the aforementioned first light ray in the aforementioned first optical system may contain a wavelength of 600 nm or more to 750 nm or less; the aforementioned second light ray in the aforementioned second optical system may contain a wavelength of 350 nm or more to 550 nm or less; and the incident angle of the aforementioned second light ray in the aforementioned second optical system may contain a wavelength of 60 ˚ or more to 85 ˚ or less.

[0012] In the aforementioned inspection device, the aforementioned determination unit may determine the shape including the size of the aforementioned defect by means of the aforementioned observation results in the aforementioned first optical system; the aforementioned determination unit may determine the position of the aforementioned defect in the thickness direction of the aforementioned film when the aforementioned shape of the aforementioned defect is a predetermined shape.

[0013] In the aforementioned inspection device, the aforementioned second optical system may also perform altered dark-field observation, and the altered dark-field observation system has performed at least one of the following actions: polarization state change, which changes the polarization state of the aforementioned second light to a polarization state that increases the amount of light penetrating the aforementioned film; wavelength change, which changes the wavelength of the aforementioned second light to a wavelength that increases the amount of light penetrating the aforementioned film; and incident angle change, which changes the incident angle of the aforementioned second light to an incident angle that increases the amount of light penetrating the aforementioned film; the aforementioned determination unit obtains the height information of the aforementioned defect from the results of the aforementioned altered dark-field observation and classifies the aforementioned defect.

[0014] In the aforementioned inspection device, the aforementioned membrane system may also include: a surface membrane, which is installed on a photomask.

[0015] In the aforementioned inspection device, the depth of focus of the aforementioned objective lens may also be smaller than the distance between the aforementioned photomask and the aforementioned surface film.

[0016] In the aforementioned inspection device, the aforementioned film system may also include: a surface film, which is mounted on a photomask; and the aforementioned first optical system for observing the patterned surface formed on the aforementioned photomask.

[0017] In the aforementioned inspection device, the aforementioned photomask may also include an extreme ultraviolet (EUV) exposure device.

[0018] The inspection method of the present invention comprises the following steps: performing bright-field observation by means of a first optical system, wherein the first optical system illuminates the film with a first light penetrating the film and receives a first observation light from the first surface of the film; performing dark-field observation by means of a second optical system, wherein the second optical system illuminates the film from the first surface with a second light reflected at the first surface of the film and receives a second observation light from the first surface of the film; and determining, by means of a determination unit, based on a combination of the observation results of the bright-field observation in the first optical system and the observation results of the dark-field observation in the second optical system, whether the position of the defect of the film when the first surface in the thickness direction of the film is taken as the upper side and the second surface opposite to the first surface is taken as the lower side is either the defect above the first surface of the film or the defect below the first surface of the film.

[0019] [Effect of the Invention] According to the present invention, an inspection device and inspection method that can determine the defects of a membrane with high accuracy can be provided.

Implementation Method

[0021] Hereinafter, the specific configuration of embodiments of the present invention will be described with reference to drawings. The following description shows preferred embodiments of the present invention, and the scope of the present invention is not limited to the following embodiments. In the following description, components with the same element symbols indicate substantially the same content.

[0022] [Implementation Form 1] This section describes the inspection device and inspection method for Implementation Form 1.

[0023] [Inspection Apparatus] Figure 1 is a configuration diagram of the inspection apparatus according to Embodiment 1. As shown in Figure 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 defects DF on the membrane 50 mounted on the test sample 40. Defects DF include foreign matter attached to the membrane 50. In addition, defects DF are not limited to foreign matter attached to the membrane 50, and may also include protrusions formed on the surface of the membrane 50 (also simply referred to as foreign matter on the surface of the membrane), holes (pinholes) formed on the surface of the membrane 50, and other abnormalities of the membrane 50 such as recesses.

[0024] The sample 40 may include, for example, a photomask. The film 50 may include, for example, a surface film mounted on the photomask. The film 50 has a first surface 51 and a second surface 52 opposite to the first surface 51. The second surface 52 faces the sample 40. Therefore, the first surface 51 faces the side opposite to the sample 40. The sample 40 may also include a photomask for exposure using EUV light. In this case, the surface film is formed to allow EUV light to pass through. Furthermore, the sample 40 is not limited to a photomask, and may also be other components such as a semiconductor substrate. The film 50 is not limited to a surface film mounted on a photomask, and may also be other components such as an insulating film or semiconductor film mounted on a semiconductor substrate via spacers. The film 50 may also be a surface film mounted before the photomask. In this case, the sample 40 may not be present near the film 50 during the detection of defects DF in the film 50.

[0025] Here, for ease of explanation, an XYZ orthogonal coordinate system is introduced. The direction orthogonal to the first surface 51 of the membrane 50 is taken as the Z-axis direction, and two mutually orthogonal directions within the plane orthogonal to the Z-axis direction are taken 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. Furthermore, the first optical system 10 may also include components other than these. The light source 11 generates a first ray L1. The first ray L1 contains a wavelength that at least partially penetrates the film 50. The first ray L1 may also contain a wavelength that is partially reflected by the film 50 and partially penetrates the film 50. The first ray L1 may also contain a wavelength that at least partially penetrates the first surface 51 of the film 50. For example, the first ray L1 in the first optical system 10 may also contain a wavelength between 600 nm and 750 nm. Specifically, the first ray L1 may also contain light with a center wavelength of 630 nm. The first ray L1 emitted from the light source 11 is reflected at the mirror 12.

[0027] The mirror 12 system includes, for example, a half mirror and a non-polarization beam splitter. The mirror 12 system reflects a portion of the incident first ray L1 to the objective lens 13.

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

[0029] The optical axis of the objective lens 13 extends in the Z-axis direction. The optical axis of the first ray L1, which is focused by the objective lens 13, extends in the Z-axis direction. Therefore, the first optical system 10 makes the optical axis of the first ray L1 perpendicular to the first surface 51 of the film 50. The first ray L1 penetrates the film 50. For example, in the case where the film 50 is a surface film, the wavelength of the first ray L1 is set to 600 nm or more and 750 nm or less, and the optical axis of the first ray L1 is made perpendicular to the first surface 51 of the film 50, thereby allowing the first ray L1 to penetrate the film 50.

[0030] The depth of focus of the objective lens 13 can also be greater than the thickness from the first surface 51 to the second surface 52 of the film 50. Furthermore, the depth of focus of the objective lens 13 can also be smaller than the distance between the photomask and the surface film. In this way, the first optical system 10 can observe defects on the first surface 51 and the second surface 52 of the film 50 without being affected by the patterned surface of the photomask. In addition, the focal point of the first ray L1 in the first optical system 10 can be aligned with the photomask, thereby enabling the first optical system 10 to observe the patterned surface formed on the photomask.

[0031] Objective lens 13 focuses the first observation ray R1 from the film 50 illuminated by the first ray L1. The optical axis of the first ray L1 and the optical axis of the first observation ray are orthogonal to the first surface 51 and the second surface of the film 50. Therefore, objective lens 13 focuses the first observation ray R1 reflected at the first surface 51 and the second surface of the film 50. The first observation ray R1 includes the reflected ray of the first ray L1 reflected at the first surface 51 and the second surface. Thus, the first optical system 10 illuminates the film 50 with the first ray L1 that penetrates the film 50 and receives the first observation ray R1 from the side of the first surface 51 of the film 50. Furthermore, in the state where the sample 40 is not set, or in the case where the film 50 is illuminated from the side of the second surface 52 with the first ray L1 that penetrates the sample 40, the first optical system 10 illuminates the film 50 with the first ray L1 that penetrates the film 50 and receives the first observation ray R1 from the side of the first surface 51 of the film 50. Thus, the first optical system 10 performs bright-field observation.

[0032] The first observation ray R1, which has passed through the objective lens 13, is incident on the lens 12. The lens 12 allows a portion of the first observation ray R1 to pass through. The first observation ray R1, which has passed through the lens 12, is incident on the wavelength selection unit 14.

[0033] The wavelength selection unit 14 may include, for example, a dichroic mirror. The wavelength selection unit 14 allows the first observation ray R1 to pass through. This allows the first observation ray R1 to be incident on the lens 15. The lens 15 focuses the incident first observation ray R1 and guides it to the first detector 16. The first observation ray R1 is intended to be focused by the first detector 16. Therefore, the first optical system 10 can function as a confocal optical system. The first detector 16 detects the first observation ray R1. The first detector 16 may be a TDI (Time Delay Integration) or a line sensor.

[0034] In addition, the wavelength selection unit 14 can also reflect the first observation light R1, thereby guiding the first observation light R1 to the first detector 16 via the lens 15. Furthermore, the wavelength selection unit 14 is not limited to a two-way beam splitter as long as it can guide the first observation light R1 to the first detector 16, and can also be combined with a half mirror and a band pass filter.

[0035] The first detector 16 is connected to the processing device 30 via a communication line in a state capable of transmitting information. The communication line includes at least one of wired and wireless methods. The first detector 16 outputs the observation results of the bright-field observation in 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 rotation unit 14, a lens 25, and a second detector 26. In this embodiment, the objective lens 13 used to receive the second observation ray R2 in the second optical system 20 is common to the objective lens 13 used to receive the first observation ray R1 in the first optical system 10. Furthermore, the wavelength selection unit 14 used to select the wavelength of the second observation ray R2 in the second optical system 20 may also be common to the wavelength selection unit 14 used to select the wavelength of the first observation ray R1 in the first optical system 10. In addition, the second optical system 20 may further include components other than these.

[0037] The light source 21 generates a second ray L2. The second ray L2 in the second optical system 20 may also contain a wavelength of 350 nm or more to 550 nm or less. Specifically, the second ray L2 may also contain light with a center wavelength of 405 nm. The second ray L2 emitted from the light source 21 is incident on the mirror 22. Furthermore, the second ray L2 emitted from the light source 21 is incident on the mirror 22 via the polarizing member 27. The polarizing member 27 changes the polarization state of the second ray L2. For example, the polarizing member 27 changes the polarization state to include S-polarized light when the second ray L2 is incident on the film 50.

[0038] Mirror 22 reflects the incident second ray L2 onto the first surface 51 of the film 50. The optical axis of the second ray L2 incident on the first surface 51 is tilted relative to the first surface 51. Thus, the second optical system 20 uses oblique incidence illumination, which is formed by tilting the optical axis of the second ray L2 relative to the first surface 51. The second ray L2 obliquely incident on the first surface 51 is reflected at the first surface 51. For example, the second ray L2 incident on the first surface 51 may also contain S-polarized light.

[0039] Figure 2 is a graph illustrating the relationship between the incident angle and transmittance of the surface film for EUV exposure in the inspection apparatus 1 of Embodiment 1, as an example. The horizontal axis shows the incident angle towards the surface film, and the vertical axis shows the transmittance towards the surface film. Figure 2 shows the transmittance of S-polarized light with a center wavelength of 750 nm and S-polarized light with a center wavelength of 550 nm.

[0040] As shown in Figure 2, the larger the incident angle, the smaller the transmittance. In this embodiment, the incident angle of the second ray L2 in the second optical system 20 is between 60˚ and 85˚. The incident angle of the second ray L2 in the second optical system 20 may also be between 60˚ and 90˚. Specifically, the incident angle of the second ray L2 is 70˚ or more, which is a Brewster angle.

[0041] For example, in the case where the film 50 is a surface film, the wavelength of the second light L2 is set to 350 nm or more and 550 nm or less, and the second light L2 is set in a manner that 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, thereby enabling the second light L2 to be reflected at the first surface 51 of the film 50.

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

[0043] The second observation ray R2, which has passed through the objective lens 13, is incident on the lens 12. The lens 12 allows a portion of the second observation ray R2 to pass through. The second observation ray R2, which has passed through the lens 12, is incident on the wavelength selection unit 14.

[0044] The wavelength selection unit 14 reflects the second observation light ray R2. This causes the second observation light ray R2 to be incident on the lens 25. The lens 25 focuses the incident second observation light ray R2 and guides it to the second detector 26. The second observation light ray R2 is intended to be focused by the second detector 26. Therefore, the second optical system 20 can function as a confocal optical system. The second detector 26 detects the second observation light ray R2. The second detector 26 can be a TDI (Transient Digital Induction Device) or a line sensor.

[0045] Furthermore, the wavelength selection unit 14 can also allow the second observation light beam R2 to pass through, thereby guiding the second observation light beam R2 to the second detector 26 via the lens 25. In addition, the wavelength selection unit 14 is not limited to a two-way beam splitter as long as it can guide the second observation light beam R2 to the second detector 26, and can also be combined with a half mirror and a bandpass filter.

[0046] The second detector 26 is connected to the processing device 30 via a communication line in a state capable of transmitting information. The communication line includes at least one of wired and wireless methods. The second detector 26 outputs the observation results of dark-field observation in 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 illustrations of the observation results of bright-field observation and dark-field observation in the inspection device 1 of Embodiment 1. Figure 3 shows the case where defect DF exists on the first surface 51 of the film 50, and Figure 4 shows the case where defect DF exists on the second surface 52 of the film 50.

[0048] When there is no defect DF on the first surface 51 and the second surface 52, the first optical system 10 receives the first observation ray R1 formed by the reflection of the first ray L1 by the film 50. Therefore, when there is no defect DF on the first surface 51 and the second surface 52, the first optical system 10 obtains a white bright-field image. However, as shown in FIG3, when there is a defect DF such as a foreign object on the first surface 51 of the film 50, the first ray L1 in bright-field observation is scattered at the defect DF. Specifically, when there is a defect DF on the first surface 51, the first observation ray R1 lacks the portion of the reflected ray of the first ray L1 that is scattered at the defect DF. In this way, the first optical system 10 can observe the defect DF such as a foreign object as a part whose brightness has been reduced in bright-field observation.

[0049] Furthermore, when the first surface 51 does not have the defect DF, the second ray L2, which has already been reflected at the first surface 51, is reflected at the same angle of reflection as the angle of incidence. Therefore, the second ray L2, which has already been reflected at the first surface 51, does not incident on the objective lens 13. Consequently, the second optical system 20 cannot receive the second observation ray R2, which includes the reflected ray formed by the reflection of the second ray L2 from the film 50. When the first surface 51 does not have the defect DF, the second optical system 20 obtains a black dark-field image. However, as shown in FIG3, when the first surface 51 of the film 50 has the defect DF, the second ray L2 is scattered at the defect DF. Therefore, the second observation ray R2 includes the scattered ray formed by the scattering of the second ray L2 by the defect DF. Consequently, the second optical system 20 can observe the defect DF, such as foreign objects, as a brighter part than the surrounding area in dark-field observation.

[0050] As shown in Figure 4, when a defect DF, such as a foreign object, exists on the second surface 52, the first ray L1 in bright-field observation is scattered at the defect DF. Therefore, the first observation ray R1 lacks the portion of the reflected ray of the first ray L1 that is scattered at the defect DF. In this way, the first optical system 10 can observe the defect DF, such as a foreign object, as a part with reduced brightness in bright-field observation.

[0051] On the other hand, since the second ray L2 is reflected at the first surface 51 of the film 50, it is not scattered by the defect DF on the second surface 52. Therefore, as shown in FIG4, in the case where there is a defect DF such as a foreign object on the second surface 52, the second observation ray R2 does not contain the scattered ray formed by the second ray L2 being scattered at the defect DF. As a result, the second optical system 20 cannot (is unable to) observe the defect DF present on the second surface 52 in dark-field observation.

[0052] The processing apparatus 30 includes a determination unit 31. The determination unit 31 functions as a determination unit. 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 the bright-field observation in the first optical system 10 and the dark-field observation in the second optical system 20. That is, the determination unit 31 determines whether the defect DF is a defect DF located above or below the first surface 51 of the film 50 based on a combination of the observation results of the bright-field observation in the first optical system 10 and the dark-field observation in the second optical system 20. Here, the side of the first surface in the thickness direction of the film 50 is considered as above, and the side of the second surface in the thickness direction of the film 50 is considered as below. Defects located below the first surface 51 may include holes (pinholes) and recesses in the film 50, and / or defects DF caused by foreign matter on the surface of the second surface. Furthermore, the determination unit 31 can also determine, based on a combination of the observation results from bright-field observation in the first optical system 10 and dark-field observation in the second optical system 20, whether the location of the defect DF in the film 50 is a defect DF in the first surface 51 of the film 50 or a defect DF in the second surface 52 of the film 50. Here, the defect DF in the first surface 51 of the film 50 includes the defect DF caused by foreign matter on the surface of the first surface 51 of the film 50, and the defect DF in the second surface 52 of the film 50 includes the defect DF caused by foreign matter on the surface of the second surface 52 of the film 50.

[0053] Figure 5 shows the observation results determined by the determination unit 31 in the inspection device 1 of Embodiment 1. As shown in Figure 5, when a defect DF is observed in both the observation results of the first optical system 10 (bright-field observation, for example, the wavelength of the first light L1 is 630 nm) and the observation results of 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 results of the first optical system 10 but not in the observation results of the second optical system 20, the determination unit 31 determines that the defect DF is below the first surface 51 of the film 50. Figure 5 is an example. Pinholes and recesses in the defect DF below the first surface 51 of the film 50 can also be observed by the observation in the second optical system 20 by adjusting the inspection device 1, as described in the second embodiment later. In this case, if the first optical system 10 observes the defect DF but the second optical system 20 does not observe the defect DF, the determination unit 31 determines that the defect DF is caused by a foreign object on the surface of the second surface 52 of the film 50.

[0054] [Variation Example 1] The determination unit 31 can also determine the size and shape of the defect DF based on the observation results of the first optical system 10. Since the optical axis of the first observation ray R1 in the first optical system 10 is orthogonal to the first surface 51, the size and shape of the defect DF seen from the direction orthogonal to the first surface 51 can be determined. For example, if the observed size of the defect DF is above a predetermined threshold value that can be determined to be a foreign object, or if the shape of the defect DF is a predetermined shape that can be determined to be a foreign object, the determination unit 31 determines which side of the film 50, the first surface 51 or the second surface 52, contains the foreign object (Classification 2). Furthermore, if the size (or shape) of the defect DF is above a predetermined second threshold value and is determined to be a foreign object in the second surface 52 of the film 50, the determination unit 31 classifies the defect DF as a defect DF that has the possibility of falling from the second surface 52 of the film 50 to the sample 40 (Classification 3).

[0055] FIG6 is a block diagram illustrating the processing unit 30 in the inspection apparatus 1 of Embodiment 1. As shown in FIG6, in addition to the determination unit 31, the processing unit 30 may further include a control unit 32 and a memory unit 33. The control unit 32 and the memory unit 33 function as a control unit and a memory unit, respectively. The processing unit 30 includes an information processing device such as a PC (personal computer) or a server.

[0056] [Variation Example 2] The control unit 32 controls the operation of the determination unit 31 and the memory unit 33 in the processing device 30. In addition, the control unit 32 can also control the operation of the first optical system 10 and the second optical system 20. Specifically, for example, in any of the following (1) to (3), the control unit 32 causes the second optical system 20 to perform any of the following: change of polarization state, change of wavelength, and change of incident angle; (1) when it is determined that there is a defect DF on the second surface 52 of the film 50; (2) when it is determined that the defect DF is a defect of a predetermined shape based on the observation results of the first optical system 10; (3) when it is determined that there is a defect DF on the second surface 52 of the film 50 and the defect DF is determined to be a defect of a predetermined shape based on the observation results of the first optical system 10.

[0057] In the wavelength change, the second optical system 20 changes the wavelength of the second light ray L2 towards a wavelength that increases the amount of light penetrating the membrane 50. Specifically, for example, the second optical system 20 increases the wavelength of the second light ray L2 to a wavelength between 600 nm and 750 nm. Furthermore, as long as the second optical system 20 can increase the amount of light penetrating the membrane 50, it can also change the wavelength of the second light ray L2 to a wavelength other than 600 nm to 750 nm.

[0058] In the incident angle change, the second optical system 20 changes the incident angle of the second ray L2 toward an angle that increases the amount of light transmitted through the transmissive film 50. Specifically, for example, the second optical system 20 may also set the incident angle of the second ray L2 to be smaller than 60˚. In the polarization state change, for example, the polarizing member 27 is controlled to change the second ray L2 to P-polarized light. The second optical system 20 performs dark-field observation, which is performed by at least one of polarization state change, wavelength change, and incident angle change. Dark-field observation that performs at least one of polarization state change, wavelength change, and incident angle change is called modified dark-field observation.

[0059] The determination unit 31 obtains the height information of the defect DF from the results of the altered dark-field observation and classifies the defect DF. Specifically, for example, if the height of the defect DF is above a predetermined first threshold value, the determination unit 31 may also classify the defect DF as a foreign object (Classification 2). Furthermore, if the height of the defect DF is above a predetermined second threshold value, the defect DF may also be classified as a defect DF that is likely to fall from the second surface 52 of the film 50 to the sample 40 (Classification 3). In addition, if the height of the defect DF is less than the predetermined first threshold value, the determination unit 31 may also classify the defect DF as a defect DF other than a foreign object, for example, classifying the defect DF as a hole (pinhole) or a recess (Classification 1).

[0060] The memory unit 33 stores the observation results. The memory unit 33 can also store the observation conditions of the first optical system 10 and the second optical system 20. The memory unit 33 can also store the height information of the defect DF and the classification of the defect DF in a related manner.

[0061] [Variation Example 3] Alternatively, the focal point of the first ray L1 in the first optical system 10 can be aligned with the photomask, thereby enabling the first optical system 10 to observe the pattern formed on the photomask.

[0062] [Inspection Method] Next, the inspection method using inspection device 1 will be described. Figure 7 is a flowchart illustrating the inspection method using inspection device 1 in Embodiment 1. In Figure 7, although the bright-field observation step S11 and the dark-field observation step S12 are performed in parallel (simultaneously), it is not limited to this. The bright-field observation step S11 may be performed before the dark-field observation step S12, or the bright-field observation step S11 may be performed after the dark-field observation step S12.

[0063] As shown in step S11 of FIG7, bright-field observation is performed. Specifically, for example, the control unit 32 can also control the first optical system 10 to perform bright-field observation of the film 50 by means of the first optical system 10. The first optical system 10 illuminates the film 50 with a first light ray L1 that penetrates the film 50 and receives the first observation light ray R1 from the side of the first surface 51 of the film 50. In step S11 of performing bright-field observation, the first optical system 10 can also set the optical axis of the first light ray L1 to be 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 can also control the second optical system 20 to perform dark-field observation of the film 50 via the second optical system 20. The second optical system 20 illuminates the film 50 from the side of the first surface 51 with the second light L2 reflected at the first surface 51 of the film 50, and receives the second observation light R2 from the side of the first surface 51. In step S12 of performing dark-field observation, the second optical system 20 can also use oblique incidence illumination, which is formed by tilting the optical axis of the second light L2 relative to the first surface 51 of the film 50. The objective lens 13 used to receive the second observation light R2 in the second optical system 20 can also be the same as the objective lens 13 used to receive the first observation light R1 in the first optical system 10.

[0065] Next, as shown in step S13, a determination is performed by the determination unit 31. 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 from the bright-field observation in the first optical system 10 and the dark-field observation in the second optical system 20. That is, the determination unit 31 determines whether the defect DF is a defect DF located above or below the first surface 51 of the film 50 based on a combination of the observation results from the bright-field observation in the first optical system 10 and the dark-field observation in the second optical system 20. Furthermore, the determination unit 31 can also determine whether the defect DF of 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 from the bright-field observation in the first optical system 10 and the dark-field observation in the second optical system 20. In step S13 of the determination process, if the determination unit 31 detects the defect DF using both the observation results from the first optical system 10 and the observation results from the second optical system 20, it can also determine that the defect DF is located above the first surface 51 of the film 50. Furthermore, if the determination unit 31 detects the defect DF using the observation results from the first optical system 10 but not using the observation results from the second optical system 20, it can determine that the defect DF is located below the first surface 51 of the film 50.

[0066] The determination unit 31 can also determine the shape of the defect DF and classify the defect DF by means of the observation results in the first optical system 10.

[0067] Figure 8 is a flowchart illustrating another inspection method using the inspection device 1 of Embodiment 1. As shown in Figure 8, it may further include a step S14 for changing dark-field observation due to changes in polarization state, wavelength, and incident angle, and a step S15 for determining the defect 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 observation result of the first optical system 10 determines that the defect DF is a defect DF of a predetermined shape, the control unit 32 controls the second optical system 20 to perform a modified dark-field observation. This modified dark-field observation involves at least one of polarization state modification, wavelength modification, and incident angle modification. Here, the wavelength modification in the second optical system 20 is to modify the wavelength of the second ray L2 towards a wavelength that increases the amount of light penetrating the film 50. The incident angle modification is to modify the incident angle of the second ray L2 towards an incident angle that increases the amount of light penetrating the film 50. The polarization state modification is to modify the polarization state of the second ray L2 towards a polarization state that increases the amount of light penetrating the film 50.

[0069] Next, as shown in step S15, the height information is determined and the defect is classified. Specifically, the determination unit 31 obtains the height information of the defect and classifies the defect DF by observing the dark field of view in the second optical system 20 after at least one of the changes in polarization state, wavelength and incident angle has been changed.

[0070] Next, the effectiveness of this embodiment will be explained. The determination unit 31 of this embodiment determines whether defects exist 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 (perpendicular incidence) which can detect defects on both the surface and back of the film and dark-field observation (oblique incidence) which only detects surface defects, defects such as foreign matter on the film and surface-back separation detection are performed. In this way, the inspection device 1 can determine the defects of the film 50 with high accuracy.

[0071] The first optical system 10 positions the optical axis of the first ray L1 perpendicular to the first surface 51. Therefore, the inspection device 1 can determine the shape and size of the defect DF by observing the first ray L1 in bright field. Specifically, the diameter of the foreign object can be calculated from the defect detected by bright field observation.

[0072] When defects such as foreign objects of predetermined size and shape adhere to the film, they become the cause of film rupture. In this embodiment, since defects of predetermined size and shape can be identified, damage can be suppressed.

[0073] Furthermore, there may be instances where foreign objects of a predetermined size and shape that have already adhered to the film may fall onto the photomask due to factors such as increased temperature. In this embodiment, since defects of the predetermined size and shape can be determined, it is possible to suppress the falling onto the photomask.

[0074] Furthermore, the second optical system 20 uses oblique incident illumination, which is configured such that the optical axis of the second ray L2 is tilted relative to the first surface 51. Moreover, it uses oblique incident illumination with a short wavelength of visible light and S-polarized light. Therefore, the second optical system 20 can perform dark-field observation and can detect defects only on the surface of the film. Thus, it can distinguish whether a defect DF exists on either the first surface 51 or the second surface 52 of the film 50.

[0075] In cases where a defect DF is determined to exist on the second surface 52 of the film 50 and the first optical system 10 determines that the defect DF is a defect DF of a predetermined shape, the second optical system 20 performs a modified dark-field observation. This modified dark-field observation involves at least one of changing the wavelength of the second ray L2 and changing the incident angle of the second ray L2. Thereby, the determination unit 31 obtains the height information of the defect DF and classifies the defect DF. Therefore, the inspection device 1 can determine the classification of defects in the film 50 with high accuracy.

[0076] By using different wavelengths for bright-field and dark-field observations, both observations can be performed simultaneously in a single scan. This shortens the observation time.

[0077] [Embodiment 2] Next, the inspection apparatus and inspection method of Embodiment 2 will be described. In this embodiment, oblique incident illumination is provided in a second optical system 20 for dark-field observation using light paths arranged in a ring around the objective lens 13 from multiple directions. Then, defects such as pinholes (DF) are determined based on the observation results of the dark-field observation.

[0078] FIG9 is a configuration diagram of the inspection apparatus 2 according to Embodiment 2. FIG10 is a cross-sectional view showing the arrangement of the objective lens 13 and the lens 22 in the second optical system 20a of the inspection apparatus 2 according to Embodiment 2, and shows the cross-section along line A-A in FIG9. FIG11 is a cross-sectional view showing the arrangement of the objective lens 13 and the lens 22 in the second optical system 20b of the inspection apparatus 2 according to Embodiment 2. FIG12 is a diagram showing the oblique incident illumination in the second optical system 20c of the inspection apparatus 2 according to Embodiment 2.

[0079] As shown in FIG. 9, in the inspection apparatus 2 of this embodiment, the second optical system 20a uses oblique incident illumination, which is formed by tilting the optical axis of the second ray L2 relative to the first surface 51 from multiple directions. The multiple directions include, for example, directions from the periphery of the objective lens 13 toward the illumination point of the second ray L2. That is, the multiple directions include radial directions viewed from the Z-axis direction with the illumination point of the second ray L2 illuminating the first surface 51 as the center. As shown in FIG. 10, the second optical system 20a may also use multiple mirrors 22, which are arranged in a ring around the objective lens 13 for receiving the second observation ray R2 at multiple positions. The second optical system 20a provides oblique incident illumination to the illumination point from multiple light paths formed by the multiple mirrors 22. Furthermore, oblique incident illumination can also be achieved by using a ring-shaped mirror 22 to provide oblique incident illumination from multiple light paths. Furthermore, in addition to using mirror 22, a plurality of optical fibers configured to surround objective lens 13 can be used to provide oblique illumination from a plurality of optical paths; or a plurality of optical fibers configured to surround objective lens 13 can be used to replace mirror 22 to provide oblique illumination from a plurality of optical paths. Furthermore, as shown in FIG11, the oblique illumination system does not need to be annular, as long as it can illuminate film 50 from at least a plurality of directions. Furthermore, the angle of incidence of oblique illumination relative to the first surface 51 of film 50 can be a fixed angle in all directions, or a plurality of angles of incidence can be used as shown in FIG12. For example, the angle of incidence of oblique illumination can also have angle θ1 and angle θ2, which is different from angle θ1.

[0080] Figure 13 shows the observation results of dark-field observation of the second optical system 20a in the inspection apparatus 2 of Embodiment 2. As shown in Figure 13, in the case of oblique incidence illumination where the second light L2 is incident from one direction (represented as "1WAY" in Figure 13), the illumination area in 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 where the second light L2 is incident from multiple annular directions (represented as "RING" in Figure 13), the illumination area in the pinhole HL covers the entire circumference of the pinhole HL, thus enabling the detection of the unique characteristics of the pinhole HL, which include scattered light from the edge of the pinhole HL. Furthermore, the pinhole HL includes a hole extending from the first surface 51 to the second surface 52 of the film 50. In addition, in the film 50 such as a surface film, there may be a recess formed on the surface of the film 50. The recesses described later include those formed on the first surface 51 of the membrane 50.

[0081] Figure 14 illustrates the observation results of bright-field and dark-field observations in the inspection apparatus 2 of Embodiment 2, showing the case where a pinhole HL exists in the film 50. As shown in the right-hand diagram of Figure 14, when a pinhole HL is formed in the film 50, the first ray L1 in bright-field observation passes through the portion of the pinhole HL. Therefore, the first observation ray R1 lacks the portion of the reflected ray of the first ray L1 that passed through the pinhole HL. In this way, the first optical system 10 can observe the portion of the pinhole HL as a portion with reduced brightness in bright-field observation. In bright-field observation, the center brightness of the portion of the pinhole HL is below a predetermined threshold value. The threshold value can also be set in advance, for example, as the brightness of the portion of the pinhole HL.

[0082] Although not shown, in the case where a recess is formed on the first surface 51, the first ray L1 in bright-field observation is incident on the recess. A portion of the first ray L1 that has been incident on the recess is scattered at the wall and bottom surfaces of the recess. Therefore, a portion of the first ray L1 that has been incident on the recess is not focused as reflected light onto the objective lens 13. However, another portion of the first ray L1 that has been incident on the recess is reflected at the bottom surface of the recess and focused as reflected light onto the objective lens 13. Therefore, although the first observation ray R1 includes the reflected light from the first ray L1 reflected at the bottom surface of the recess, it lacks the portion scattered at the recess. Therefore, the first optical system 10 can observe the recessed portion as a portion with reduced brightness and as a portion with brightness exceeding a predetermined threshold value in bright-field observation. Therefore, in bright-field observation, although the center brightness of the recessed portion exceeds the predetermined threshold value, it is low brightness.

[0083] As shown in the left side of Figure 14, the second ray L2 in dark-field observation under oblique incidence illumination is scattered at the edge of the pinhole HL. In this embodiment, since the oblique incidence illumination causes the second ray L2 to be incident from multiple directions, the second ray L2 is scattered at the edge of the entire circumference of the pinhole HL. Therefore, the second observation ray R2 includes the scattered rays from the second ray L2 scattered at the edge of the entire circumference of the pinhole HL. Thus, the second optical system 20a can observe the edge of the pinhole HL as a high-brightness region in dark-field observation.

[0084] Furthermore, although not shown, in the case where the first surface 51 has a recess, the second ray L2 in dark-field observation under oblique incident illumination is scattered at the edge of the recess. In this embodiment, since the oblique incident illumination causes the second ray L2 to be incident from multiple directions, the second ray L2 is scattered at the entire circumference of the edge of the recess. Therefore, the second observation ray R2 includes the scattered ray L2 scattered at the entire circumference of the edge of the recess. Thus, the second optical system 20a can observe the edge of the recess as a high-brightness area in dark-field observation.

[0085] Figures 15 and 16 illustrate brightness graphs in the bright-field and dark-field observation results of the inspection apparatus 2 in Embodiment 2. The horizontal axis shows the position on the film 50 along the X-axis, and the vertical axis shows the brightness. As shown in Figures 15 and 16, in the case of observing annular defects in dark-field observation, the center brightness of the defect in bright-field observation can be used to determine whether the defect formed on the film 50 is a pinhole HL or a recess.

[0086] As shown in Figures 15 and 16, in bright-field observation of the film 50 with pinholes HL and recesses, the edges of the pinholes HL and recesses are difficult to determine because the brightness changes caused by their gradual changes. In contrast, in dark-field observation, the brightness changes caused by the edges of the pinholes HL and recesses are abrupt. Therefore, the edges of the pinholes HL and recesses can be determined. This allows for the determination of the diameter of the first surface 51 of the pinholes HL and recesses.

[0087] Figure 17 illustrates the observation results of bright-field and dark-field observations in the inspection apparatus 2 of Embodiment 2, and shows the presence of particles on the first surface 51 of the film 50. As shown in Figure 17, when particles are present on the first surface 51 of the film 50, the first ray L1 in bright-field observation is scattered by the particles. Therefore, the first optical system 10 can observe the particles as parts with reduced brightness in bright-field observation.

[0088] On the other hand, the second ray L2 in dark-field observation under oblique incident illumination is scattered by particles. Therefore, the second optical system 20 can observe particles as brighter than their surroundings in dark-field observation. In this embodiment, since the oblique incident illumination system causes the second ray L2 to be incident from multiple directions, the brightness of the scattered light caused by particles can be set to be higher than the brightness shown in FIG3, thus improving detection precision.

[0089] Figure 18 illustrates the observation results determined by the determination unit 31 in the inspection device 2 of Embodiment 2. As shown in Figure 18, in the case where a defect DF is observed in both the bright-field observation in the first optical system 10 and the dark-field observation in the second optical system 20 under oblique incident illumination from multiple directions, and in the case where a non-annular defect 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 of the defect on the first surface 51 by means of bright-field observation.

[0090] On the other hand, if the defect DF is observed using the first optical system 10 but not using the second optical system 20, the determination unit 31 determines that the defect DF is located below the first surface 51 of the film 50. The determination unit 31 determines the diameter of the defect projected onto the first surface 51 of the defect by observing with a bright field of view. Classifications two and three are as explained above.

[0091] In the case where a defect DF is observed by both the bright-field observation in the first optical system 10 and the dark-field observation under oblique incident illumination from multiple directions in the second optical system 20, and where a ring-shaped defect is observed in the dark-field observation and the center brightness of the defect in the bright-field observation is below a threshold value, the determination unit 31 determines that it is a pinhole HL formed on the film 50. In this case, the determination unit 31 determines the size of the pinhole HL based on both the bright-field and dark-field observations. That is, the determination unit 31 determines that the defect DF is a pinhole HL based on the observation results of both the bright-field and dark-field observations, and determines the diameter of the first surface 51 of the pinhole HL based on the observation results of the dark-field observation.

[0092] In the case where a defect DF is observed by both the bright-field observation in the first optical system 10 and the dark-field observation under oblique incident illumination from multiple directions in the second optical system 20, and where a ring-shaped defect is observed in the dark-field observation and the center brightness of the defect in the bright-field observation exceeds a threshold value, the determination unit 31 determines that it is a recess formed on the film 50. In this case, the determination unit 31 determines the size of the recess based on both the bright-field and dark-field observations. That is, the determination unit 31 determines that the defect DF is a recess based on the observation results of both the bright-field and dark-field observations, and determines the diameter of the first surface 51 of the recess based on the observation results of the dark-field observation.

[0093] The determination unit 31 can also determine the classification of the defect DF based on the observation results of dark-field observation in oblique incident illumination from multiple directions of the second optical system 20. That is, when the defect DF is observed by dark-field observation in the second optical system 20, the determination unit 31 determines whether it is a foreign object, a pinhole HL, or a recess on the first surface 51. When the defect DF is not observed by dark-field observation in the second optical system 20, the determination unit 31 determines whether it is a foreign object below the first surface 51 or whether there is no defect. Moreover, when the observation results of dark-field observation in the second optical system 20 show that the defect DF is not annular, the determination unit 31 determines that it is a foreign object on the first surface 51. When the observation results of dark-field observation in the second optical system 20 show that the defect DF is annular, the determination unit 31 determines whether it is a pinhole HL or a recess. Furthermore, in the case where a ring-shaped defect DF is observed by means of dark-field observation in the second optical system 20, if the center brightness of the defect is below the threshold value according to the observation results of bright-field observation in the first optical system 10, the determination unit 31 determines it to be a pinhole HL; if the center brightness of the defect exceeds the threshold value according to the observation results of bright-field observation in the first optical system 10, the determination unit 31 determines it to be a recess.

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

[0095] Next, the inspection method will be explained. In this embodiment, in step S12 of performing dark-field observation, the second optical system 20 uses oblique incident illumination, which is formed by tilting the optical axis of the second ray L2 relative to the first surface 51 in a plurality of directions. In step S12 of performing dark-field observation, the second optical system 20 can also provide oblique incident illumination from a plurality of light paths set at a plurality of positions, which are arranged in a ring around the objective lens 13 receiving the second observation ray R2.

[0096] In step S13 of the determination process, the classification of the defect DF is determined based on the observation results of dark-field observation in the second optical system 20. Here, the classification of the defect DF includes pinholes HL and recesses. In step S13 of the determination process, the dimensions of the pinholes HL and recesses can also be determined based on the observation results of bright-field observation in the first optical system 10 and the observation results of dark-field observation in the second optical system 20.

[0097] In step S13 of the determination process, if the defect DF is classified as a foreign object, the size of the foreign object is determined based on the observation results of the bright-field observation in the first optical system 10. If the defect DF is classified as a pinhole HL or a recess, the size of the pinhole HL and the recess can also be determined based on the observation results of the bright-field observation in the first optical system 10 and the observation results of the dark-field observation in the second optical system 20.

[0098] According to this embodiment, the pinhole HL of the film 50 and the recess of the first surface 51 of the film 50 can be observed as annular scattered light by dark-field observation using the second optical system 20. In this case, combined with bright-field observation using the first optical system 10, the pinhole HL and the recess can be distinguished. Furthermore, the inspection device 2 of this embodiment can accurately measure the dimensions of the pinhole HL and the first surface 51 of the recess.

[0099] [Embodiment 3] Next, the inspection apparatus and inspection method of Embodiment 3 will be described. In the inspection apparatus 1 of Embodiment 1, the determination unit 31 determines whether the defect DF of the film 50 is a defect DF located above or below the first surface 51 of the film 50, based on a combination of observation results from bright-field observation in the first optical system 10 and dark-field observation in the second optical system 20. In this embodiment, the size of the defect DF is determined without this determination as a prerequisite.

[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 ray L1 that penetrates the film 50, and receives a first observation light ray R1 from the side of the first surface 51 of the film 50. The second optical system 20 illuminates the film 50 from the side of the first surface 51 with a second light ray L2 reflected at the first surface 51, and receives a second observation light ray R2 from the side of the first surface 51. The second optical system 20 uses oblique incidence illumination, which is formed by tilting the optical axis of the second light ray L2 relative to the first surface 51 in a plurality of directions. The second optical system 20 can also provide oblique incidence illumination from a plurality of light paths provided at a plurality of positions, which are arranged in a ring around the objective lens 13 that receives the second observation light ray R2.

[0101] The determination unit 31 determines the size of the dented defect formed on the first surface 51 of the film 50 based on a combination of the observation results from the bright-field observation in the first optical system 10 and the dark-field observation in the second optical system 20. The dented defect includes pinholes HL and recesses. Furthermore, if the defect is classified as a foreign object, the determination unit 31 determines the size of the foreign object based on the observation results from the bright-field observation in the first optical system 10; if the defect is classified as a dented defect, the determination unit 31 determines the size of the dented defect based on the observation results from the bright-field observation in the first optical system 10 and the dark-field observation in the second optical system 20. In this configuration, the size of the dented defect on the first surface 51 can be measured with high precision. Additionally, the determination unit 31 can also determine the classification of the dented defect formed on the film 50 based on a combination of the observation results from the bright-field observation in the first optical system 10 and the dark-field observation in the second optical system 20. That is, when a ring-shaped defect DF is observed by means of dark-field observation in the second optical system 20, if the center brightness of the defect is below the threshold value when detecting at least one of the pinhole HL and the recess, the determination unit 31 determines that the defect is the pinhole HL. If the center brightness of the defect exceeds the threshold value when detecting at least one of the pinhole HL and the recess, the determination unit 31 determines that the defect is the recess.

[0102] The inspection method of this embodiment includes: step S11, which is to perform bright-field observation; step S12, which is to perform dark-field observation; and step S13, which is to make a determination. In step S11, which is to perform bright-field observation, the film 50 is illuminated by a first light ray L1 that penetrates the film 50, and the first observation ray R1 is received from the side of the first surface 51 of the film 50. In step S12, which is to perform dark-field observation, the film 50 is illuminated from the side of the first surface 51 by a second light ray L2 reflected at the first surface 51 of the film 50, and the second observation ray R2 is received from the side of the first surface 51. The second optical system 20 uses oblique incident illumination, which is formed by tilting the optical axis of the second light ray L2 relative to the first surface 51 in a plurality of directions. The second optical system 20 performs oblique incident illumination from a plurality of light paths provided at a plurality of positions, which are arranged in a ring around the objective lens 13 that receives the second observation ray R2.

[0103] In step S13 of the determination process, the determination unit 31 determines the size of the entrapment defect formed on the first surface 51 of the film 50 based on a combination of the observation results from the bright-field observation in the first optical system 10 and the dark-field observation in the second optical system 20. In step S13, if the defect DF is classified as a foreign object, the size of the foreign object is determined based on the observation results from the bright-field observation in the first optical system 10. If the defect DF is classified as an entrapment defect, the size of the entrapment defect is determined based on the observation results from the bright-field observation in the first optical system 10 and the dark-field observation in the second optical system 20. In step S13, the classification of the entrapment defect formed on the film 50 is determined based on a combination of the observation results from the bright-field observation in the first optical system 10 and the dark-field observation in the second optical system 20.

[0104] Although the embodiments of the present invention have been described above, the present invention also includes suitable variations that do not impair the purpose and effectiveness of the present invention, and the present invention is not limited to the embodiments described above. Furthermore, the scope of the various components of embodiments one to three appropriately omitted or combined is also within the scope of the technical concept of the present invention. In addition, the following configurations are also within the scope of the technical concept of the embodiments.

[0105] [Appendix 1] An inspection method comprising the following steps: performing bright-field observation by means of a first optical system, wherein the first optical system illuminates the film with a first light penetrating the film and receives a first observation light from the side of the first surface of the film; performing dark-field observation by means of a second optical system, wherein the second optical system illuminates the film with a second light reflected at the first surface of the film from the side of the first surface and receives a second observation light from the side of the first surface; and determining, by means of a determination unit, based on a combination of the observation results of the bright-field observation in the first optical system and the observation results of the dark-field observation in the second optical system, whether the position of a defect in the film when the side of the first surface in the thickness direction of the film is taken as the upper part and the side of the second surface opposite to the first surface is taken as the lower part is either a defect that is higher than the first surface of the film or a defect that is lower than the first surface of the film. [Appendix 2] In the inspection method described in Appendix 1, if the aforementioned defect is detected by both the observation results in the first optical system and the observation results in the second optical system during the aforementioned determination step, it is determined that the defect is located above the first surface; if the aforementioned defect is detected by the observation results in the first optical system but not by the observation results in the second optical system during the aforementioned determination step, it is determined that the defect is located below the first surface. [Appendix 3] In the inspection method described in Appendix 1, if the aforementioned defect is detected by both the observation results in the first optical system and the observation results in the second optical system during the aforementioned determination step, it is determined that the defect is caused by a foreign object on the surface of the first surface; if the aforementioned defect is detected by the observation results in the first optical system but not by the observation results in the second optical system during the aforementioned determination step, it is determined that the defect is caused by a foreign object on the surface of the second surface. [Appendix 4] As described in Appendix 1, in the step of performing the aforementioned bright-field observation, the aforementioned first optical system sets the optical axis of the aforementioned first light ray to be perpendicular to the aforementioned first surface; in the step of performing the aforementioned dark-field observation, the aforementioned second optical system uses oblique incident illumination, and the aforementioned oblique incident illumination sets the optical axis of the aforementioned second light ray to be inclined relative to the aforementioned first surface; the objective lens used in the aforementioned second optical system to receive the aforementioned second observation light ray is common to the aforementioned objective lens used in the aforementioned first optical system to receive the aforementioned first observation light ray.[Appendix 5] In the inspection method described in Appendix 4, in the step of performing the aforementioned bright-field observation, the aforementioned first optical system illuminates the aforementioned film from the side of the aforementioned first surface with the aforementioned first light beam; the aforementioned objective lens focuses the aforementioned first light beam of the aforementioned first optical system onto the aforementioned film. [Appendix 6] In the inspection method described in Appendix 1, in the step of performing the aforementioned bright-field observation, the aforementioned first light beam in the aforementioned first optical system has a wavelength of 600 nm or more to 750 nm or less; in the step of performing the aforementioned dark-field observation, the aforementioned second light beam in the aforementioned second optical system has a wavelength of 350 nm or more to 550 nm or less; the incident angle of the aforementioned second light beam in the aforementioned second optical system has a wavelength of 60˚ or more to 85˚ or less. [Appendix 7] In the inspection method described in Appendix 1, in the step of performing the aforementioned determination, the shape including the size of the aforementioned defect is determined by the aforementioned observation result in the aforementioned first optical system; in the case where the aforementioned shape of the aforementioned defect is a predetermined shape, the position of the aforementioned defect in the thickness direction of the aforementioned film is determined. [Appendix 8] The inspection method described in Appendix 1 further includes the following steps: performing altered dark-field observation in the aforementioned second optical system, wherein the altered dark-field observation has performed at least one of the following actions: polarization state change, which changes the polarization state of the aforementioned second light beam towards a polarization state that increases the amount of light penetrating the aforementioned film; wavelength change, which changes the wavelength of the aforementioned second light beam towards a wavelength that increases the amount of light penetrating the aforementioned film; and incident angle change, which changes the incident angle of the aforementioned second light beam towards an incident angle that increases the amount of light penetrating the aforementioned film; and obtaining height information of the aforementioned defect from the result of the altered dark-field observation and classifying the aforementioned defect. [Appendix 9] The inspection method described in Appendix 4, wherein the aforementioned film includes: a surface film, which is mounted on the photomask. [Appendix 10] The inspection method described in Appendix 9, wherein the depth of focus of the aforementioned objective lens is smaller than the distance between the aforementioned photomask and the aforementioned surface film. [Appendix 11] The inspection method described in Appendix 5, wherein the aforementioned film system comprises: a surface film, which is mounted on a photomask; the aforementioned inspection method further comprises the step of: observing the patterned surface formed on the aforementioned photomask in the aforementioned first optical system. [Appendix 12] The inspection method described in Appendix 9, wherein the aforementioned photomask comprises an extreme ultraviolet exposure device. [Appendix 13] The inspection method described in Appendix 1, wherein in the step of performing the aforementioned dark-field observation, the aforementioned second optical system uses oblique incident illumination, and the aforementioned oblique incident illumination sets the optical axis of the aforementioned second light rays to be inclined relative to the aforementioned first surface from a plurality of directions; in the step of performing the aforementioned determination, the classification of the aforementioned defect is determined based on the aforementioned observation results of the aforementioned dark-field observation in the aforementioned second optical system; the classification of the aforementioned defect includes pinholes.[Appendix 14] In the inspection method described in Appendix 13, in the step of performing the aforementioned dark-field observation, the aforementioned second optical system provides oblique incident illumination from a plurality of light paths disposed at a plurality of positions, the plurality of positions being arranged in a ring around the objective lens receiving the aforementioned second observation light. [Appendix 15] In the inspection method described in Appendix 13, in the step of performing the aforementioned determination, the size of the aforementioned pinhole is determined based on the aforementioned observation results of the aforementioned bright-field observation in the aforementioned first optical system and the aforementioned observation results of the aforementioned dark-field observation in the aforementioned second optical system. [Appendix 16] The inspection method described in Appendix 15, wherein in the step of making the aforementioned determination, in the case where the aforementioned defect is classified as a foreign object, the size of the aforementioned foreign object is determined based on the observation results of the aforementioned bright-field observation in the aforementioned first optical system; in the step of making the aforementioned determination, in the case where the aforementioned defect is classified as a aforementioned pinhole, the size of the aforementioned pinhole is determined based on the observation results of the aforementioned bright-field observation in the aforementioned first optical system and the aforementioned dark-field observation in the aforementioned second optical system. [Appendix A1] An inspection apparatus comprising: a first optical system that illuminates the film with a first light penetrating the film and receives a first observation light from a first surface side of the film; a second optical system that illuminates the film from a first surface side with a second light reflected from the first surface of the film and receives a second observation light from the first surface side; and a determination unit that determines the size of a recessed defect, including at least one of a pinhole and a recess formed in the film, in the first surface based on a combination of observation results from bright-field observation in the first optical system and dark-field observation in the second optical system; the second optical system uses oblique incidence illumination, wherein the optical axis of the second light is set to be inclined relative to the first surface from a plurality of directions. [Appendix A2] The inspection apparatus described in Appendix A1, wherein the second optical system provides oblique incidence illumination from a plurality of light paths disposed at a plurality of positions, the plurality of positions being annularly surrounding an objective lens receiving the second observation light. [Appendix A3] The inspection device described in Appendix A1, wherein the aforementioned determination unit classifies the aforementioned defect as a foreign object or a crater defect based on the aforementioned observation results of the aforementioned dark-field observation in the aforementioned second optical system; the aforementioned determination unit determines the size of the aforementioned foreign object based on the aforementioned observation results of the aforementioned bright-field observation in the aforementioned first optical system when the aforementioned defect is classified as a foreign object; and the aforementioned determination unit determines the size of the aforementioned crater defect based on the aforementioned observation results of the aforementioned bright-field observation in the aforementioned first optical system and the aforementioned observation results of the aforementioned dark-field observation in the aforementioned second optical system when the aforementioned defect is classified as a crater defect.[Appendix B1] An inspection method comprising the steps of: performing bright-field observation with a first optical system, wherein the first optical system illuminates the film with a first light penetrating the film and receives a first observation light from the side of a first surface of the film; performing dark-field observation with a second optical system, wherein the second optical system illuminates the film from the side of the first surface with a second light reflected at the first surface of the film and receives a second observation light from the side of the first surface; and determining, by a determination unit, the size of the first surface containing at least one of a pinhole and a recess formed in the film based on a combination of the observation results of the bright-field observation in the first optical system and the observation results of the dark-field observation in the second optical system; wherein, in the step of performing the dark-field observation, the second optical system uses oblique incident illumination, wherein the oblique incident illumination sets the optical axis of the second light to be inclined relative to the first surface from a plurality of directions. [Appendix B2] As described in Appendix B1, in the step of performing the aforementioned dark-field observation, the aforementioned second optical system provides oblique incident illumination from a plurality of light paths located at a plurality of positions, the plurality of positions being arranged in a ring around the objective lens receiving the aforementioned second observation light. [Appendix B3] As described in Appendix B1, in the step of performing the aforementioned determination, based on the aforementioned observation results of the aforementioned dark-field observation in the aforementioned second optical system, the aforementioned defect is classified as either a foreign object or a dented defect; in the step of performing the aforementioned determination, in the case where the aforementioned defect is classified as a foreign object, the size of the aforementioned foreign object is determined based on the aforementioned bright-field observation results of the aforementioned first optical system; in the step of performing the aforementioned determination, in the case where the aforementioned defect is classified as a dented defect, the size of the aforementioned dented defect is determined based on the aforementioned observation results of the aforementioned bright-field observation in the aforementioned first optical system and the aforementioned observation results of the aforementioned dark-field observation in the aforementioned second optical system. [Appendix C1] An inspection apparatus comprising: a first optical system that illuminates the film with a first light penetrating the film and receives a first observation light from a first surface side of the film; a second optical system that illuminates the film from a first surface side with a second light reflected at the first surface side of the film and receives a second observation light from the first surface side; and a determination unit that, based on the observation results of dark-field observation in the second optical system, determines the detection of a dent defect including at least one of a pinhole and a recess formed in the film, and classifies the dent defect into either the pinhole or the recess based on the observation results of bright-field observation in the first optical system; wherein the second optical system uses oblique incident illumination, and the oblique incident illumination is configured such that the optical axis of the second light is inclined relative to the first surface from a plurality of directions.[Appendix C2] The inspection apparatus as described in Appendix C1, wherein the aforementioned second optical system provides oblique incident illumination from a plurality of light paths located at a plurality of positions, the plurality of positions being arranged in a ring around the objective lens receiving the aforementioned second observation light. [Appendix D1] An inspection method comprising the following steps: performing bright-field observation with a first optical system, wherein the first optical system illuminates the film with a first light penetrating the film and receives the first observation light from the side of the first surface of the film; performing dark-field observation with a second optical system, wherein the second optical system illuminates the film from the side of the first surface with a second light reflected at the first surface of the film and receives the second observation light from the side of the first surface; and a determination step, which, based on the observation results of the bright-field observation in the first optical system, determines the detection of a dent defect including at least one of a pinhole and a recess formed in the film, and classifies the dent defect into either the pinhole or the recess based on the observation results of the dark-field observation in the second optical system; in the step of performing the dark-field observation, the second optical system uses oblique incident illumination, wherein the oblique incident illumination sets the optical axis of the second light to be inclined relative to the first surface from a plurality of directions. [Appendix D2] The inspection method described in Appendix D1, wherein in the step of performing the aforementioned dark-field observation, the aforementioned second optical system provides oblique incident illumination from a plurality of light paths located at a plurality of positions, the plurality of positions being circularly arranged around the objective lens receiving the aforementioned second observation light. [Appendix E1] An inspection apparatus comprising: a first optical system that allows a first light to pass through and illuminate a film, and receives a first observation light from a first surface of the film; a second optical system that allows a second light to reflect from the first surface of the film and illuminate the film from the first surface, and receives a second observation light from the first surface; and a determination unit that classifies defects in the film based on a combination of observation results from bright-field observation in the first optical system and dark-field observation in the second optical system; the second optical system uses oblique incident illumination, wherein the oblique incident illumination sets the optical axis of the second light to be inclined relative to the first surface from a plurality of directions; and the determination unit classifies the defects into any one of (1) defects caused by foreign matter on the first surface, (2) defects caused by foreign matter on the second surface, and (3) dent defects on the film.[Appendix F1] An inspection method comprising the following steps: performing a bright-field observation in a first optical system, wherein the first optical system is configured to allow a first light to pass through and illuminate the film and to receive the first observation light from the side of the first surface of the film; performing a dark-field observation in a second optical system, wherein the second optical system is configured to allow a second light to be reflected from the first surface of the film and to illuminate the film from the side of the first surface and to receive the second observation light from the side of the first surface; and classifying defects of the film in a determination unit based on a combination of the observation results of the bright-field observation in the first optical system and the observation results of the dark-field observation in the second optical system; in the step of performing the determination, the defects of the film are classified into any one of (1) defects caused by foreign matter on the first surface, (2) defects caused by foreign matter on the second surface, and (3) entrapment defects on the film. [Simplified Explanation of the Diagram]

[0020] [Figure 1] is a structural diagram of the inspection apparatus according to Embodiment 1. [Figure 2] is a graph showing the relationship between the incident angle and transmittance of the EUV exposure film in the inspection apparatus of Embodiment 1. The horizontal axis shows the incident angle towards the film, and the vertical axis shows the transmittance towards the film. [Figure 3] is a diagram showing the observation results of bright-field and dark-field observations in the inspection apparatus of Embodiment 1, showing the situation where defects exist on the first side of the film. [Figure 4] is a diagram showing the observation results of bright-field and dark-field observations in the inspection apparatus of Embodiment 1, showing the situation where defects exist on the second side of the film. [Figure 5] is a diagram showing the observation results determined by the judgment unit in the inspection apparatus of Embodiment 1. [Figure 6] is a block diagram showing the processing device in the inspection apparatus of Embodiment 1. [Figure 7] is a flowchart showing the inspection method using the inspection apparatus of Embodiment 1. [Figure 8] is a flowchart showing another inspection method using the inspection apparatus of Embodiment 1. [Figure 9] is a structural diagram illustrating the inspection apparatus of Embodiment 2. [Figure 10] is a cross-sectional view illustrating the arrangement of the objective lens and mirror in the second optical system of the inspection apparatus of Embodiment 2, showing the cross-section along line A-A in Figure 9. [Figure 11] is a cross-sectional view illustrating the arrangement of the objective lens and mirror in the second optical system of the inspection apparatus of Embodiment 2. [Figure 12] is a diagram illustrating oblique incident illumination in the second optical system of the inspection apparatus of Embodiment 2. [Figure 13] is a diagram illustrating the observation results of dark-field observation in the second optical system of the inspection apparatus of Embodiment 2. [Figure 14] is a diagram illustrating the observation results of bright-field and dark-field observation in the inspection apparatus of Embodiment 2, showing the case where pinholes exist on the film. [Figure 15] is a graph illustrating the brightness in the bright-field and dark-field observation results of the inspection apparatus of Embodiment 2, with the horizontal axis showing the position on the film along the X-axis and the vertical axis showing the brightness. [Figure 16] is a graph showing the brightness of the film in the bright-field and dark-field observations in the inspection apparatus of Embodiment 2, for example. The horizontal axis shows the position of the film along the X-axis, and the vertical axis shows the brightness. [Figure 17] is a graph showing the bright-field and dark-field observation results in the inspection apparatus of Embodiment 2, showing the presence of particles on the first surface of the film. [Figure 18] is a graph showing the observation results determined by the determination unit in the inspection apparatus of Embodiment 2.

Claims

1. An inspection apparatus comprising: a first optical system for illuminating the film with a first light penetrating the film and receiving a first observation light from a first surface side of the film; a second optical system for illuminating the film with a second light reflected from the first surface side of the film and receiving a second observation light from the first surface side of the film; and a determination unit for determining, based on a combination of observation results from a bright-field image in the first optical system and observation results from a dark-field image in the second optical system, whether the location of a defect in the film, when the first surface side in the thickness direction of the film is considered above and the second surface side, which is the opposite side of the first surface, is considered below, is either a defect located above the first surface of the film or a defect located below the first surface of the film.

2. The inspection apparatus as described in claim 1, wherein in the bright field image of the first optical system, the defect is a portion with lower brightness than the surrounding area; and in the dark field image of the second optical system, the defect is a portion with higher brightness than the surrounding area.

3. The inspection device as described in claim 1, wherein the determination unit determines the shape of the defect based on the bright-field image in the first optical system.

4. The inspection device as described in claim 1, wherein the determination unit determines that the defect is located above the first surface when the defect is detected by both the observation results of the first optical system and the observation results of the second optical system; and the determination unit determines that the defect is located below the first surface when the defect is detected by the observation results of the first optical system but not by the observation results of the second optical system.

5. The inspection apparatus as described in claim 1, wherein the first optical system sets the optical axis of the first light beam perpendicular to the first surface; the second optical system uses oblique incident illumination, wherein the oblique incident illumination sets the optical axis of the second light beam inclined relative to the first surface; and the objective lens in the second optical system for receiving the second observation light beam is common to the objective lens in the first optical system for receiving the first observation light beam.

6. The inspection apparatus as described in claim 5, wherein the aforementioned first optical system illuminates the aforementioned film from the side of the aforementioned first surface with the aforementioned first light; the aforementioned objective lens for focusing the aforementioned first light of the aforementioned first optical system onto the aforementioned film is common to the aforementioned objective lens for receiving the aforementioned first observation light and the aforementioned second observation light.

7. The inspection apparatus as described in claim 5, wherein the aforementioned membrane system includes: a surface membrane, which is mounted on a photomask.

8. The inspection apparatus as described in claim 7, wherein the depth of focus of the aforementioned objective lens is smaller than the distance between the aforementioned photomask and the aforementioned coating.

9. The inspection apparatus as described in claim 6, wherein the aforementioned film system comprises: a surface film mounted on a photomask; and the aforementioned first optical system for observing the patterned surface formed on the aforementioned photomask.

10. The inspection apparatus as described in claim 7, wherein the aforementioned photomask includes an extreme ultraviolet exposure photomask.

11. The inspection apparatus as described in claim 1, wherein the first ray in the first optical system has a wavelength of 600 nm or more to 750 nm or less; the second ray in the second optical system has a wavelength of 350 nm or more to 550 nm or less; and the incident angle of the second ray in the second optical system is 60˚ or more to 85˚ or less.

12. The inspection apparatus as described in claim 1, wherein the determination unit determines the shape including the size of the aforementioned defect by means of the aforementioned observation results in the aforementioned first optical system; the determination unit determines the position of the aforementioned defect in the thickness direction of the aforementioned film when the aforementioned shape of the aforementioned defect is a predetermined shape.

13. The inspection apparatus described in claim 1, wherein the aforementioned second optical system performs altered dark-field observation, and the altered dark-field observation has performed at least one of the following actions: polarization state change, which changes the polarization state of the aforementioned second light to a polarization state that increases the amount of light penetrating the aforementioned film; wavelength change, which changes the wavelength of the aforementioned second light to a wavelength that increases the amount of light penetrating the aforementioned film; and incident angle change, which changes the incident angle of the aforementioned second light to an incident angle that increases the amount of light penetrating the aforementioned film; the aforementioned determination unit obtains the height information of the aforementioned defect from the result of the altered dark-field observation and classifies the aforementioned defect.

14. The inspection apparatus as described in claim 1, wherein the second optical system uses oblique incident illumination, wherein the oblique incident illumination sets the optical axis of the second light ray to be inclined relative to the first surface from a plurality of directions; the determination unit determines the classification of the defect based on the observation results of the dark-field image in the second optical system; the classification of the defect includes pinholes.

15. The inspection apparatus as described in claim 14, wherein the aforementioned second optical system provides oblique incident illumination from a plurality of light paths disposed at a plurality of positions, the plurality of positions being arranged in annularly around the objective lens receiving the aforementioned second observation light.

16. The inspection device as described in claim 14, wherein the determination unit determines the size of the pinhole based on the observation results of the bright-field image in the first optical system and the dark-field image in the second optical system.

17. The inspection device as described in claim 16, wherein the determination unit determines the size of the foreign object based on the observation results of the bright-field image in the first optical system when the defect is classified as a foreign object; and the determination unit determines the size of the pinhole based on the observation results of the bright-field image in the first optical system and the dark-field image in the second optical system when the defect is classified as a pinhole.

18. An inspection apparatus comprising: a first optical system that illuminates the film with a first light penetrating the film and receives a first observation light from a first surface of the film; a second optical system that illuminates the film from a first surface with a second light reflected from the first surface of the film and receives a second observation light from the first surface; and a determination unit that determines the location of a defect in the film based on a combination of observation results from a bright-field image in the first optical system and observation results from a dark-field image in the second optical system; wherein the determination unit determines that the defect is caused by a foreign object on the surface of the first surface when the defect is detected by both the observation results in the first optical system and the observation results in the second optical system; and wherein the determination unit determines that the defect is caused by a foreign object on the surface of a second surface opposite to the first surface when the defect is detected by the observation results in the first optical system but not by the observation results in the second optical system.

19. The inspection apparatus as described in claim 18, wherein in the bright field image of the first optical system, the defect is a portion with lower brightness than the surrounding area; and in the dark field image of the second optical system, the defect is a portion with higher brightness than the surrounding area.

20. The inspection apparatus as described in claim 18, wherein the determination unit determines the shape of the defect based on the bright-field image in the first optical system.

21. An inspection method comprising the steps of: performing bright-field observation using a first optical system, wherein the first optical system illuminates the film with a first light penetrating the film and receives a first observation light from the side of a first surface of the film; performing dark-field observation using a second optical system, wherein the second optical system illuminates the film from the side of the first surface with a second light reflected at the first surface of the film and receives a second observation light from the side of the first surface; and determining, based on a combination of observation results from the bright-field image in the first optical system and observation results from the dark-field image in the second optical system, whether the location of a defect in the film, when the side of the first surface in the thickness direction of the film is taken as the upper part and the side of the second surface opposite to the first surface is taken as the lower part, is either a defect located above the first surface of the film or a defect located below the first surface of the film.

22. The inspection method as described in claim 21, wherein in the bright-field image of the first optical system, the defect is a portion whose brightness is lower than the surrounding area; and in the dark-field image of the second optical system, the defect is a portion whose brightness is higher than the surrounding area.

23. The inspection method as described in claim 21, wherein the aforementioned determination unit determines the shape of the aforementioned defect based on the aforementioned bright-field image in the aforementioned first optical system.

24. An inspection method comprising the steps of: performing bright-field observation using a first optical system, wherein the first optical system illuminates the film with a first light penetrating the film and receives the first observation light from a first surface of the film; performing dark-field observation using a second optical system, wherein the second optical system illuminates the film from a first surface using a second light reflected at the first surface of the film and receives the second observation light from the first surface; and determining the location of a defect in the film by a determination unit based on a combination of observation results from a bright-field image in the first optical system and observation results from a dark-field image in the second optical system; in the determination step, if the defect is detected by both the observation results from the first optical system and the observation results from the second optical system, the defect is determined to be caused by a foreign object on the surface of the first surface; In the step of making the aforementioned determination, if the aforementioned defect is detected by the aforementioned observation results in the aforementioned first optical system but not by the aforementioned observation results in the aforementioned second optical system, it is determined that the aforementioned defect is caused by a foreign object on the surface of the second surface opposite to the aforementioned first surface.

25. The inspection method as described in claim 24, wherein in the bright-field image of the first optical system, the defect is a portion whose brightness is lower than the surrounding area; and in the dark-field image of the second optical system, the defect is a portion whose brightness is higher than the surrounding area.

26. The inspection method as described in claim 24, wherein the aforementioned determination unit determines the shape of the aforementioned defect based on the aforementioned bright-field image in the aforementioned first optical system.

Images