Inspection device and inspection method

Abstract

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

Description

Technical Field

[0001] The present disclosure relates to an inspection apparatus and an inspection method.

Background Art

[0002] Patent Document 1 proposes an inspection method using a dark-field illumination system capable of discriminating whether a foreign object on a pellicle is on the front surface or the back surface of the pellicle.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

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

[0005] The present disclosure has been made to solve the above problems, and an object thereof is to provide an inspection apparatus and an inspection method capable of determining a defect in a film with high accuracy.

Means for Solving the Problems

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

[0007] In the above inspection apparatus, the determination unit may determine that the defect is above the first surface if the defect is detected in both the observation results of the first optical system and the observation results of the second optical system, and may determine that the defect is below the first surface if the defect is detected in the observation results of the first optical system and not detected in the observation results of the second optical system.

[0008] In the above inspection apparatus, the determination unit may determine that the defect is caused by foreign matter on the surface of the first surface if the defect is detected in both the observation results of the first optical system and the observation results of the second optical system, or it may determine that the defect is caused by foreign matter on the surface of the second surface if the defect is detected in the observation results of the first optical system and the defect is not detected in the observation results of the second optical system.

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

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

[0011] In the above inspection apparatus, the first light in the first optical system includes a wavelength of 600 nm to 750 nm, the second light in the second optical system includes a wavelength of 350 nm to 550 nm, and the incident angle of the second light in the second optical system may include 60° to 85°.

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

[0013] In the above inspection apparatus, the second optical system may perform modified dark-field observation by changing the polarization state of the second light to a polarization state in which the amount of light transmitted through the film increases, changing the wavelength of the second light to a wavelength in which the amount of light transmitted through the film increases, and changing the incident angle of the second light to an incident angle in which the amount of light transmitted through the film increases. The determination unit may then obtain height information of the defects from the results of the modified dark-field observation and classify the defects.

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

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

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

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

[0018] The inspection method according to the present disclosure includes a step of performing bright-field observation with a first optical system that illuminates the film with first light that passes through the film and receives first observation light from the first surface side of the film, a step of performing dark-field observation with a second optical system that illuminates the film from the first surface side with second light that is reflected by the first surface of the film and receives second observation light from the first surface side, and a step of determining, by a determination unit, whether the position of the defect in the film in the thickness direction is a defect above the first surface of the film or a defect below the first surface, based on a combination of the observation result of the bright-field observation by the first optical system and the observation result of the dark-field observation by the second optical system, with the first surface side in the thickness direction of the film being above and the second surface side opposite to the first surface being below.

Effect of the Invention

[0019] According to the present disclosure, it is possible to provide an inspection apparatus and an inspection method capable of determining defects in a film with high accuracy.

Brief Description of the Drawings

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

Mode for Carrying Out the Invention

[0021] The specific configuration of this embodiment will be described below with reference to the drawings. The following description illustrates preferred embodiments of the present disclosure, and the scope of the present disclosure is not limited to the following embodiments. In the following description, the same reference numerals indicate substantially the same components.

[0022] <Embodiment 1> The inspection apparatus and inspection method according to Embodiment 1 will be described.

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

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

[0025] For the sake of explanation, we introduce the XYZ Cartesian coordinate system. The direction perpendicular to the first surface 51 of the film 50 is defined as the Z-axis direction, and the two mutually orthogonal directions within the plane perpendicular to the Z-axis direction are defined as the X-axis direction and the Y-axis direction.

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

[0027] The mirror 12 includes, for example, a half-mirror and an unpolarized beam splitter. The mirror 12 reflects a portion of the incident first light L1 toward the objective lens 13.

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

[0029] The optical axis of the objective lens 13 extends in the Z-axis direction. The optical axis of the first light L1 focused by the objective lens 13 also extends in the Z-axis direction. Therefore, the first optical system 10 aligns the optical axis of the first light L1 perpendicular to the first surface 51 of the film 50. The first light L1 passes through the film 50. For example, if the film 50 is a pellicle, by setting the wavelength of the first light L1 to between 600 nm and 750 nm and aligning the optical axis of the first light L1 perpendicular to the first surface 51 of the film 50, the first light L1 passes through the film 50.

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

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

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

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

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

[0035] The first detector 16 is connected to the processing unit 30 in a manner that enables information transmission via a communication line including at least one of wired and wireless connections. The first detector 16 outputs the observation results of bright-field observation in the first optical system 10 to the processing unit 30.

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

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

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

[0039] Figure 2 is a graph illustrating the relationship between the incident angle to the pellicle for EUV exposure and the transmittance in the inspection apparatus 1 according to Embodiment 1. The horizontal axis represents the incident angle to the pellicle, and the vertical axis represents the transmittance to the pellicle. Figure 2 shows the transmittance of S-polarized light with a central wavelength of 750 nm and S-polarized light with a central wavelength of 550 nm.

[0040] As shown in Figure 2, the transmittance decreases as the angle of incidence increases. In this embodiment, the angle of incidence of the second light L2 in the second optical system 20 includes 60° to 85°. Specifically, the angle of incidence of the second light L2 includes the Brewster angle of 70° or more.

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

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

[0043] The second observation light R2, having passed through the objective lens 13, enters the mirror 12. The mirror 12 transmits a portion of the second observation light R2. The second observation light R2 that has passed through the mirror 12 enters the wavelength selection unit 14.

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

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

[0046] The second detector 26 is connected to the processing unit 30 in a manner that enables information transmission via a communication line including at least one of wired and wireless connections. The second detector 26 outputs the observation results of dark-field observation in the second optical system 20 to the processing unit 30.

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

[0048] If there are no defects DF on the first surface 51 and the second surface 52, the first optical system 10 receives the first observation light R1, which is the first light L1 reflected by the film 50. Therefore, if there are no defects DF on the first surface 51 and the second surface 52, the first optical system 10 acquires a white bright-field image. However, as shown in Figure 3, if there are defects DF such as foreign matter on the first surface 51 of the film 50, the first light L1 in bright-field observation is scattered by the defects DF. Specifically, if there are defects DF on the first surface 51, the first observation light R1 lacks the portion of the reflected light L1 that is scattered by the defects DF. As a result, the first optical system 10 can observe the defects DF such as foreign matter as a portion with reduced brightness in bright-field observation.

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

[0050] As shown in Figure 4, if there is a defect DF such as a foreign object on the second surface 52, the first light L1 in bright-field observation is scattered by the defect DF. Therefore, the first observation light R1 lacks the portion of the reflected light L1 that was scattered by the defect DF. As a result, the first optical system 10 can observe the defect DF, such as a foreign object, as a portion with reduced brightness in bright-field observation.

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

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

[0053] Figure 5 is a diagram illustrating the observation results determined by the determination unit 31 in the inspection apparatus 1 according to Embodiment 1. As shown in Figure 5, if a defect DF is observed in both the observation results from the first optical system 10 (bright-field observation, for example, with a wavelength of 630 nm for the first light L1) and the observation results from the second optical system 20 (dark-field observation, for example, with a wavelength of 405 nm for the second light L2 including S polarization), the determination unit 31 determines that the defect DF is located above the first surface 51 of the film 50. On the other hand, if a defect DF is observed in the observation results from the first optical system 10, and no defect DF is observed in the observation results from 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.

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

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

[0056] <Modification 2> The control unit 32 controls the operation of the determination unit 31 and the storage unit 33 in the processing device 30. The control unit 32 may also control the operation of the first optical system 10 and the second optical system 20. Specifically, for example, in any of the following cases, the control unit 32 causes the second optical system 20 to perform at least one of the following: change of polarization state, change of wavelength, and change of incident angle.

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

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

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

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

[0061] <Variation 3> The first optical system 10 may observe the patterned surface formed on the photomask by focusing the first light L1 on the photomask.

[0062] <Testing Method> Next, an inspection method using the inspection device 1 will be described. Figure 7 is a flowchart illustrating an inspection method using the inspection device 1 according to Embodiment 1. In Figure 7, the bright-field observation step S11 and the dark-field observation step S12 are performed in parallel (simultaneously), but the method 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] Bright-field observation is performed as shown in step S11 of Figure 7. Specifically, for example, the control unit 32 may control the first optical system 10 to perform bright-field observation of the film 50. The first optical system 10 illuminates the film 50 with a first light L1 that passes through the film 50 and receives a first observation light R1 from the first surface 51 side of the film 50. In step S11, in which bright-field observation is performed, the optical axis of the first light L1 of the first optical system 10 may be perpendicular to the first surface 51 of the film 50.

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

[0065] Next, as shown in step S13, the determination unit 31 makes a determination. Specifically, the determination unit 31 determines the position of the defect DF in the thickness direction of the film 50 based on a combination of the observation results of bright-field observation in the first optical system 10 and the observation results of dark-field observation in the second optical system 20. That is, the determination unit 31 determines whether the defect DF is located above the first surface 51 of the film 50 or below the first surface 51, based on a combination of the observation results of bright-field observation in the first optical system 10 and the observation results of dark-field observation in the second optical system 20. Alternatively, the determination unit 31 may determine whether the defect DF of the film 50 is located on the first surface 51 or on the second surface 52, based on a combination of 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. In the determination step S13, the determination unit 31 may determine that the defect DF is located above the first surface 51 of the film 50 if the defect DF is observed in both the observation results from the first optical system 10 and the observation results from the second optical system 20. Alternatively, the determination unit 31 may determine that the defect DF is located below the first surface 51 of the film 50 if the defect DF is detected in the observation results from the first optical system 10 and not detected in the observation results from the second optical system 20.

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

[0067] Figure 8 is a flowchart illustrating another inspection method using the inspection apparatus 1 according to Embodiment 1. As shown in Figure 8, the flowchart may further include steps S14 for modified dark-field observation by changing the polarization state, wavelength, and incident angle, and step S15 for determining the defect DF.

[0068] As shown in step S14, if it is determined that a defect DF exists on the second surface 52 of the film 50, and the observation results of the first optical system 10 indicate that the defect DF is of a predetermined shape, the control unit 32 controls the second optical system 20 to perform modified dark-field observation by changing the polarization state, changing the wavelength, and changing the incident angle. Here, changing the wavelength in the second optical system 20 means changing the wavelength of the second light L2 to a wavelength that increases the amount of light transmitted through the film 50. Changing the incident angle means changing the incident angle of the second light L2 to an incident angle that increases the amount of light transmitted through the film 50. Changing the polarization state means changing the polarization state of the second light L2 to a polarization state that increases the amount of light transmitted through the film 50.

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

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

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

[0072] It is believed that defects such as foreign objects of a predetermined size and shape adhering to the pellicle can cause film breakage. In this embodiment, since defects of a predetermined size and shape can be determined, damage can be suppressed.

[0073] Furthermore, foreign matter of a predetermined size and shape adhering to the pellicle may fall onto the photomask due to rising temperatures or other factors. In this embodiment, since defects of a 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 incidence illumination with the optical axis of the second light source L2 tilted relative to the first surface 51. In addition, it uses oblique incidence illumination of short wavelength and S polarization of visible light. Therefore, the second optical system 20 can perform dark-field observation and detect only defects on the surface of the pellicle. Thus, it is possible to distinguish whether a defect DF exists on either the first surface 51 or the second surface 52 of the film 50.

[0075] If a defect DF is determined to exist on the second surface 52 of the film 50, and the observation results of the first optical system 10 indicate that the defect DF is of a predetermined shape, the second optical system 20 performs modified dark-field observation by changing at least one of the following: changing the wavelength of the second light L2 or changing the incident angle of the second light. As a result, the determination unit 31 acquires 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 observation, it is possible to perform both simultaneously in a single scan. This reduces observation time.

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

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

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

[0080] Figure 13 is a diagram illustrating the observation results of dark-field observation of the second optical system 20a in the inspection apparatus 2 according to Embodiment 2. As shown in Figure 13, in the case of oblique incidence illumination in which the second light L2 is incident from one direction (1WAY), it may be difficult to detect the pinhole HL because the illumination area at the edge of the pinhole HL is small. On the other hand, in the case of oblique incidence illumination in which the second light L2 is incident from multiple directions in a ring shape (RING), the illumination area of ​​the pinhole HL extends to the entire edge of the pinhole HL, so it is possible to detect the unique characteristics of the pinhole HL, including scattered light from the edge of the pinhole HL. Note that the pinhole HL includes a hole that penetrates from the first surface 51 to the second surface 52 of the film 50. In addition, in the case of a film 50 such as a pellicle, a depression may be formed on the surface of the film 50. The depression described later includes a depression formed on the first surface 51 of the film 50.

[0081] Figure 14 is a diagram illustrating the observation results of bright-field and dark-field observation in the inspection apparatus 2 according to 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 light L1 in bright-field observation passes through the portion of the pinhole HL. Therefore, the first observation light R1 lacks the portion of the reflected light of the first light L1 that has passed through the pinhole HL. As a result, 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 central brightness of the portion of the pinhole HL is below a predetermined threshold. The threshold may be set in advance as, for example, the brightness of the portion of the pinhole HL.

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

[0083] As shown in the left diagram of Figure 14, the second light L2 in dark-field observation with oblique incidence illumination is scattered at the edge of the pinhole HL. In this embodiment, since the second light L2 is incident from multiple directions in the oblique incidence illumination, the second light L2 is scattered at the entire circumference of the edge of the pinhole HL. Therefore, the second observation light R2 is the second light L2 This includes scattered light scattered around the entire edge of the pinhole HL. As a result, the second optical system 20a can observe the edge of the pinhole HL as a high-luminosity area in dark-field observation.

[0084] Furthermore, although not shown in the figures, if a recess is formed on the first surface 51, the second light L2 in dark-field observation with oblique incidence illumination will be scattered at the edge of the recess. In this embodiment, since the oblique incidence illumination causes the second light L2 to be incident from multiple directions, the second light L2 will be scattered at the edge of the recess all around. Therefore, the second observation light R2 will be scattered at the edge of the recess. L2 This includes scattered light scattered around the entire edge of the recess. Therefore, the second optical system 20a can observe the edge of the recess as a high-luminosity area in dark-field observation.

[0085] Figures 15 and 16 are graphs illustrating the brightness in bright-field and dark-field observation results in the inspection apparatus 2 according to Embodiment 2. The horizontal axis indicates the position on the film 50 along the X-axis, and the vertical axis indicates the brightness. As shown in Figures 15 and 16, when a ring-shaped defect is observed in dark-field observation, it is possible to determine whether the defect formed on the film 50 is a pinhole HL or a depression based on the brightness of the center of the defect in bright-field observation.

[0086] As shown in Figures 15 and 16, in bright-field observation of the film 50 with pinholes HL and depressions formed therein, the change in brightness due to the edges of the pinholes HL and depressions is gradual, making it difficult to determine the edges of the pinholes HL and depressions. In contrast, in dark-field observation, the change in brightness due to the edges of the pinholes HL and depressions is steep. Therefore, it is possible to determine the edges of the pinholes HL and depressions. This makes it possible to determine the diameter size of the pinholes HL and depressions on the first surface 51.

[0087] Figure 17 is an example of the observation results of bright-field and dark-field observation in the inspection apparatus 2 according to Embodiment 2, showing 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 light L1 in bright-field observation is scattered by the particles. As a result, the first optical system 10 can observe the particles as areas with reduced brightness in bright-field observation.

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

[0089] Figure 18 is a diagram illustrating the observation results determined by the determination unit 31 in the inspection apparatus 2 according to Embodiment 2. As shown in Figure 18, the determination unit 31 determines the defect DF when a defect DF is observed in both the bright-field observation results in the first optical system 10 and the dark-field observation results in oblique incidence illumination from multiple directions in the second optical system 20, and when a non-ring-shaped defect is observed in the dark-field observation. case In this case, the defect DF is determined to be located above the first surface 51 of the film 50. In this case, the determination unit 31 determines the diameter size of the defect on the first surface 51 by bright-field observation.

[0090] On the other hand, if a defect DF is observed in the observation results of the first optical system 10, and no defect DF is observed in the observation results of 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 size of the diameter projected onto the first surface 51 of the defect by bright-field observation. Classifications 2 and 3 are as described above.

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

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

[0093] The determination unit 31 may classify the defect DF based on the observation results of dark-field observation with oblique incidence illumination from multiple directions in the second optical system 20. In other words, if a defect DF is observed by dark-field observation in the second optical system 20, the determination unit 31 determines that it is either a foreign object, a pinhole HL, or a dent on the first surface 51. If no defect DF is observed by dark-field observation in the second optical system 20, the determination unit 31 determines that it is a foreign object below the first surface 51 or that there is no defect. Furthermore, if a non-ring-shaped defect DF is observed by dark-field observation in the second optical system 20, the determination unit 31 determines that it is a foreign object on the first surface 51. If a ring-shaped defect DF is observed by dark-field observation in the second optical system 20, the determination unit 31 determines that it is either a pinhole HL or a dent. Furthermore, if a ring-shaped defect DF is observed based on the dark-field observation results in the second optical system 20, the determination unit 31 determines it to be a pinhole HL based on the bright-field observation results in the first optical system 10 if the central brightness of the defect is below a threshold, and determines it to be a dent if the central brightness of the defect exceeds the threshold.

[0094] If 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 bright-field observation in the first optical system 10. If the defect is classified as a pinhole HL or a dent, the determination unit 31 determines the size of the pinhole HL or dent 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.

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

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

[0097] In the determination 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 of bright-field observation in the first optical system 10. If the defect DF is classified as a pinhole and a dent, the size of the pinhole HL and the dent may 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.

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

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

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

[0101] The determination unit 31 determines the size of the depression defect on the first surface 51 of the film 50 based on a combination of the observation results from bright-field observation in the first optical system 10 and the observation results from dark-field observation in the second optical system 20. The depression defect includes pinholes HL and indentations. If the classification (type) of the defect is a foreign object, the determination unit 31 may determine the size of the foreign object based on the observation results from bright-field observation in the first optical system 10, and if the classification (type) of the defect is a depression defect, it may determine the size of the depression defect based on the observation results from bright-field observation in the first optical system 10 and the observation results from dark-field observation in the second optical system 20. Even with this configuration, the size of the depression defect on the first surface 51 can be measured with high accuracy. Furthermore, the determination unit 31 may determine the classification of the depression defect formed on the film 50 based on a combination of the observation results from bright-field observation in the first optical system 10 and the observation results from dark-field observation in the second optical system 20. In other words, the determination unit 31 detects a depression defect that includes at least one of a pinhole HL and a depression when a ring-shaped defect DF is observed based on the observation results of dark-field observation with the second optical system 20, and determines that the depression defect is a pinhole HL if the central brightness of the defect is below a threshold based on the observation results of bright-field observation with the first optical system 10, and determines that the depression defect is a depression if the central brightness of the defect exceeds a threshold.

[0102] The inspection method of this embodiment comprises a step S11 for performing bright-field observation, a step S12 for performing dark-field observation, and a step S13 for making a determination. In the bright-field observation step S11, the film 50 is illuminated with a first light L1 that passes through the film 50 and the first observation light R1 is received from the first surface 51 side of the film 50. In the dark-field observation step S12, the film 50 is illuminated from the first surface 51 side with a second light L2 that is reflected by the first surface 51 of the film 50 and the second observation light R2 is received from the first surface 51 side. The second optical system 20 uses oblique incidence illumination in which the optical axis of the second light L2 is tilted from multiple directions with respect to the first surface 51. R2 The objective lens 13 that receives the light is illuminated by oblique incident light from multiple optical paths located at multiple positions that surround the lens in a ring shape.

[0103] In the determination step S13, the determination unit 31 determines the size of the first surface 51 of the depression defect formed on the film 50 based on a combination of 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. In the determination step, if the classification of the defect DF is a foreign object, the size of the foreign object is determined based on the observation results of bright-field observation in the first optical system 10. If the classification of the defect DF is a depression defect, the size of the depression defect is 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. In the determination step S13, the classification of the depression defect formed on the film 50 may also be determined based on a combination of 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.

[0104] While embodiments of this disclosure have been described above, this disclosure includes appropriate modifications that do not impair its purpose and advantages, and is not limited by the embodiments described above. Furthermore, appropriate omissions and combinations of the configurations of Embodiments 1 to 3 are also within the scope of the technical concept of this disclosure. The following configurations are also within the scope of the technical concept of the embodiments.

[0105] (Note 1) The steps include: performing bright-field observation with a first optical system that illuminates the film with a first light that passes through the film and receives a first observation light from the first surface side of the film; The steps include: performing dark-field observation with a second optical system that illuminates the film from the first surface side with second light reflected from the first surface of the film and receives second observation light from the first surface side; A step in which a determination unit determines, 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 location of the defect in the film is above the first surface or below the first surface, when the first surface side in the thickness direction of the film is considered upward and the second surface side opposite the first surface is considered downward; A testing method equipped with [a specific feature / feature]. (Note 2) In the determination step described above, If the defect is detected in both the observation results from the first optical system and the observation results from the second optical system, it is determined that the defect is located above the first surface. If the defect is detected in the observation results of the first optical system, and the defect is not detected in the observation results of the second optical system, then it is determined that the defect is located below the first surface. See Appendix 1 for the testing method. (Note 3) In the determination step described above, If the defect is detected in both the observation results from the first optical system and the observation results from the second optical system, it is determined that the defect is caused by foreign matter on the surface of the first surface. If the defect is detected in the observation results from the first optical system, and the defect is not detected in the observation results from the second optical system, then it is determined that the defect is caused by foreign matter on the surface of the second surface. 、 The inspection method described in Appendix 1. (Note 4) In the step of performing the bright-field observation, The first optical system aligns the optical axis of the first light to be perpendicular to the first plane. In the step of performing the dark-field observation, The second optical system uses oblique incidence illumination in which the optical axis of the second light is tilted with respect to the first plane. The objective lens that receives the second observation light in the second optical system is the same as the objective lens that receives the first observation light in the first optical system. The inspection method described in Appendix 1. (Note 5) In the step of performing the bright-field observation, The first optical system illuminates the film from the first surface side with the first light, The objective lens focuses the first light from the first optical system onto the film. The inspection method described in Appendix 4. (Note 6) In the step of performing the bright-field observation, The first light in the first optical system includes wavelengths between 600 nm and 750 nm. In the step of performing the dark-field observation, The second light in the second optical system includes wavelengths between 350 nm and 550 nm. The incident angle of the second light in the second optical system includes an angle between 60° and 85°. The inspection method described in Appendix 1. (Note 7) In the determination step described above, Based on the observation results in the first optical system, the shape, including the size of the defect, is determined. When the shape of the defect is a predetermined shape, the position of the defect in the thickness direction of the film is determined. The inspection method described in Appendix 1. (Note 8) The steps include performing a modified dark-field observation in the second optical system by changing the polarization state of the second light to a polarization state in which the amount of light transmitted through the film increases, changing the wavelength of the second light to a wavelength in which the amount of light transmitted through the film increases, and changing the incident angle of the second light to an incident angle in which the amount of light transmitted through the film increases, The steps include obtaining height information of the defects from the results of the modified dark-field observation and classifying the defects, Furthermore, The inspection method described in Appendix 1. (Note 9) The aforementioned film includes a pellicle attached to a photomask. The inspection method described in Appendix 4. (Note 10) The depth of focus of the objective lens is smaller than the distance between the photomask and the pellicle. The inspection method described in Appendix 9. (Note 11) The aforementioned film includes a pellicle attached to a photomask, The first optical system further comprises the step of observing the patterned surface formed on the photomask, The inspection method described in Appendix 5. (Note 12) The aforementioned photomask includes one for EUV exposure. The inspection method described in Appendix 9. (Note 13) In the step of performing the dark-field observation, The second optical system uses oblique incidence illumination in which the optical axis of the second light is tilted with respect to the first plane from multiple directions. In the determination step described above, Based on the observation results of the dark-field observation using the second optical system, the classification of the defect is determined. The aforementioned classification of defects includes pinholes, The inspection method described in Appendix 1. (Note 14) In the step of performing the dark-field observation, The second optical system illuminates the objective lens that receives the second observation light from multiple obliquely incident light paths located at multiple positions that surround the objective lens in a ring shape. The inspection method described in Appendix 13. (Note 15) In the determination step described above, Based on 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, the size of the pinhole is determined. The inspection method described in Appendix 13. (Note 16) In the determination step described above, If the aforementioned defect 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. If the classification of the defect is a pinhole, the size of the pinhole is determined based on 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. The inspection method described in Appendix 15. (Note A1) A first optical system that illuminates the film with first light passing through the film and receives 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 second light reflected from the first surface of the film and receives second observation light from the first surface side, A determination unit that determines the size of a depression defect on the first surface of the film, which includes at least one of a pinhole and a depression, based on a combination of the observation results of bright-field observation with the first optical system and the observation results of dark-field observation with the second optical system, Equipped with, The second optical system uses oblique incidence illumination in which the optical axis of the second light is tilted with respect to the first plane from multiple directions. Inspection device. (Appendix A2) The second optical system illuminates the objective lens that receives the second observation light from multiple obliquely incident light paths located at multiple positions that surround the objective lens in a ring shape. The inspection device described in Appendix A1. (Note A3) The determination unit, Based on the observation results of the dark-field observation in the second optical system, the defect is classified as either a foreign object or a depression defect. If the aforementioned defect 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. If the classification of the defect is a depression defect, then the depression defect is determined based on 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. Fall Determine the size, The inspection device described in Appendix A1. (Note B1) The steps include: performing bright-field observation with a first optical system that illuminates the film with a first light that passes through the film and receives a first observation light from the first surface side of the film; The steps include: performing dark-field observation with a second optical system that illuminates the film from the first surface side with second light reflected from the first surface of the film and receives second observation light from the first surface side; A step in which a determination unit determines the size of a depression defect on the first surface of the film, which includes at least one of a pinhole and a depression, 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, Equipped with, In the step of performing the dark-field observation, The second optical system uses oblique incidence illumination in which the optical axis of the second light is tilted with respect to the first plane from multiple directions. Testing method. (Note B2) In the step of performing the dark-field observation, The second optical system illuminates the objective lens that receives the second observation light from multiple obliquely incident light paths located at multiple positions that surround the objective lens in a ring shape. The inspection method described in Appendix B1. (Note B3) In the determination step described above, Based on the observation results of the dark-field observation in the second optical system, the defect is classified as either a foreign object or a depression defect. If the aforementioned defect 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. If the classification of the defect is a depression defect, the size of the depression defect is determined based on 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. The inspection method described in Appendix B1. (Note C1) A first optical system that illuminates the film with first light passing through the film and receives 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 second light reflected from the first surface of the film and receives second observation light from the first surface side, A determination unit that determines whether a depression defect, including at least one of a pinhole and a depression, is detected in the film based on the observation results of dark-field observation with the second optical system, and classifies the depression defect as either a pinhole or a depression based on the observation results of bright-field observation with the first optical system, Equipped with, The second optical system uses oblique incidence illumination in which the optical axis of the second light is tilted with respect to the first plane from multiple directions. Inspection device. (Note C2) The second optical system illuminates the objective lens that receives the second observation light from multiple obliquely incident light paths located at multiple positions that surround the objective lens in a ring shape. The inspection device described in Appendix C1. (Note D1) The steps include: performing bright-field observation with a first optical system that illuminates the film with a first light that passes through the film and receives a first observation light from the first surface side of the film; The steps include: performing dark-field observation with a second optical system that illuminates the film from the first surface side with second light reflected from the first surface of the film and receives second observation light from the first surface side; A determination step of determining whether a depression defect, including at least one of a pinhole and a depression, is detected in the film based on the observation results of the bright-field observation in the first optical system, and classifying the depression defect as either a pinhole or a depression based on the observation results of the dark-field observation in the second optical system, Equipped with, In the step of performing the dark-field observation, The second optical system uses oblique incidence illumination in which the optical axis of the second light is tilted with respect to the first plane from multiple directions. Testing method. (Note D2) In the step of performing the dark-field observation, The second optical system illuminates the objective lens that receives the second observation light from multiple obliquely incident light paths located at multiple positions that surround the objective lens in a ring shape. The testing method described in Appendix D1. [Explanation of symbols]

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

Claims

1. A first optical system that illuminates the film with first light that passes through the film and receives 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 second light reflected from the first surface of the film and receives second observation light from the first surface side, A determination unit determines, based on a combination of the observation results of a bright-field image from the first optical system and the observation results of a dark-field image from the second optical system, whether the location of the defect in the film is above the first surface or below the first surface, when the first surface side in the thickness direction of the film is considered upward and the second surface side opposite the first surface is considered downward. An inspection device equipped with the following features.

2. In the bright-field image of the first optical system, the defect is a portion in which the brightness is reduced relative to the surrounding area. The inspection apparatus according to claim 1, wherein 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 apparatus according to claim 1, wherein the determination unit determines the shape of the defect based on the change in brightness in the bright-field image in the first optical system.

4. The determination unit, If the defect is detected in both the observation results from the first optical system and the observation results from the second optical system, it is determined that the defect is located above the first surface. If the defect is detected in the observation results of the first optical system, and the defect is not detected in the observation results of the second optical system, then it is determined that the defect is located below the first surface. The inspection apparatus according to claim 1.

5. The determination unit, If the defect is detected in both the observation results from the first optical system and the observation results from the second optical system, it is determined that the defect is caused by foreign matter on the surface of the first surface. If the defect is detected in the observation results of the first optical system, and the defect is not detected in the observation results of the second optical system, then it is determined that the defect is caused by foreign matter on the surface of the second surface. The inspection apparatus according to claim 1.

6. The first optical system aligns the optical axis of the first light to be perpendicular to the first plane, The second optical system uses oblique incidence illumination in which the optical axis of the second light is tilted with respect to the first plane. The objective lens that receives the second observation light in the second optical system is the same as the objective lens that receives the first observation light in the first optical system. The inspection apparatus according to claim 1.

7. The first optical system illuminates the film from the first surface side with the first light, The objective lens focuses the first light from the first optical system onto the film. The inspection apparatus according to claim 6.

8. The first light in the first optical system includes wavelengths of 600 nm to 750 nm. The second light in the second optical system includes wavelengths of 350 nm to 550 nm. The incident angle of the second light in the second optical system includes an angle of 60° or more and an angle of 85° or less. The inspection apparatus according to claim 1.

9. The second optical system performs modified dark-field observation by changing the polarization state of the second light to a polarization state in which the amount of light transmitted through the film increases, changing the wavelength of the second light to a wavelength in which the amount of light transmitted through the film increases, and changing the incident angle of the second light to an incident angle in which the amount of light transmitted through the film increases. The determination unit obtains height information of the defect from the results of the modified dark-field observation and classifies the defect. The inspection apparatus according to claim 1.

10. The aforementioned film includes a pellicle attached to a photomask. The inspection apparatus according to claim 6.

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

12. The aforementioned film includes a pellicle attached to a photomask, The first optical system observes the patterned surface formed on the photomask. The inspection apparatus according to claim 7.

13. The aforementioned photomask includes one for EUV exposure. The inspection apparatus according to claim 10.

14. The steps include: performing bright-field observation with a first optical system that illuminates the film with a first light that passes through the film and receives a first observation light from the first surface side of the film; The steps include: performing dark-field observation with a second optical system that illuminates the film from the first surface side with second light reflected from the first surface of the film and receives second observation light from the first surface side; Based on a combination of the observation results of the bright-field image from the first optical system and the observation results of the dark-field image from the second optical system, the determination unit determines whether the location of the defect in the film, when the first surface side in the thickness direction of the film is considered upward and the second surface side opposite the first surface is considered downward, is the defect above the first surface of the film or the defect below the first surface. A testing method equipped with [a specific feature / feature].

15. The second optical system uses oblique incidence illumination in which the optical axis of the second light is tilted with respect to the first plane from multiple 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 aforementioned classification of defects includes pinholes, The inspection apparatus according to claim 1.

16. The second optical system illuminates the objective lens that receives the second observation light from multiple obliquely incident light paths located at multiple positions that surround the objective lens in a ring shape. The inspection apparatus according to claim 15.

17. The determination unit determines the size of the pinhole based on the change in brightness of the dark-field image in the second optical system. The inspection apparatus according to claim 15.

18. The determination unit, If the aforementioned defect is classified as a foreign object, the size of the foreign object is determined based on the change in brightness of the bright-field image in the first optical system. If the classification of the defect is a pinhole, the size of the pinhole is determined based on the change in brightness of the dark-field image in the second optical system. The inspection apparatus according to claim 16.

Images