JP2010122121A - Surface inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface inspection device capable of inspecting with higher sensitivity. <P>SOLUTION: In the surface inspection device 1, an illumination optical system 30 has a constitution having a first polarization element 33 for polarizing light from a lighting system 31, where polarized light acquired by transmission through the first polarization element 33 from the lighting system 31 is irradiated onto the wafer 10 surface. Also, an imaging optical system 40 has a constitution having a second polarization element 43 arranged in the crossed nicol state with respect to the first polarization element 33, where the light, acquired by transmission through the second polarization element 43 from the wafer 10 surface onto which the polarized light is irradiated, is detected. The first polarization element 33 and the second polarization element 43 have each constitution having a plurality of polarization members 34-36, 44-46 disposed side by side on an optical path and having each mutually different wavelength characteristic of an extinction ratio. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a surface inspection apparatus that inspects a pattern formed on a surface of a substrate to be tested such as a semiconductor wafer using polarized light.

  2. Description of the Related Art Conventionally, as an inspection apparatus for inspecting the presence or absence of an abnormality in a repeated pattern (resist pattern, etched pattern, etc.) formed on the surface of a wafer, an inspection apparatus using structural birefringence due to a repeated pattern has been proposed. . This is because inspection is performed by detecting light of a component orthogonal to the polarization component of the illumination light among the reflected light from the repetitive pattern illuminated with linearly polarized light by arranging the polarizing elements in a crossed Nicol state. Yes (see, for example, Patent Document 1). As a result, it is possible to inspect a minute repetitive pattern that does not emit diffracted light, and to inspect the illumination light without shortening the wavelength.

In such an inspection apparatus, the detection sensitivity of light obtained by structural birefringence changes according to the extinction ratio of the polarizing element. The extinction ratio of a polarizing element is the power of a plane polarized beam passing through a polarizing element placed in an optical path whose polarization axis is parallel to the plane of the beam, and transmission when the polarization axis is placed perpendicular to the plane of the beam. It is the ratio with power. Therefore, a polarizing element having a high extinction ratio for each illumination wavelength is prepared so that the extinction ratio becomes high regardless of the illumination wavelength.
JP 2006-135211 A

  However, when the illumination wavelength is short, the extinction ratio of the polarizing element for a long wavelength is low. Therefore, in order to obtain a polarizing element having a high extinction ratio, it is necessary to select a relatively expensive polarizing element.

  The present invention has been made in view of such a problem, and an object thereof is to provide a surface inspection apparatus capable of performing a more sensitive inspection.

  In order to achieve such an object, a surface inspection apparatus according to the present invention detects an illumination unit that irradiates polarized light onto the surface of a test substrate, and reflected light from the surface of the test substrate irradiated with the polarized light. A detection unit; and an inspection unit that inspects the surface of the test substrate based on the light detected by the detection unit. The illumination unit includes a first polarizing element that converts light from a light source into the polarized light. And configured to irradiate the surface of the substrate to be tested with the polarized light obtained by transmitting the first polarizing element from the light source, and the detection unit is polarized by the first polarizing element. A second polarizing element arranged so that a direction crossing the polarization direction of the polarized light is a polarization direction, and transmitted through the second polarizing element from the surface of the test substrate irradiated with the polarized light. Configured to detect the obtained light, and the first bias is detected. At least one of element and the second polarizing element is configured with a plurality of polarization member wavelength characteristics are different from each other along the optical path in the optical path disposed the extinction ratio.

  In the surface inspection apparatus described above, it is preferable that the wavelength characteristics of the extinction ratio in the plurality of polarizing members are close to each other.

  In the surface inspection apparatus described above, the polarizing member is preferably a polarizing cube beam splitter.

  In the surface inspection apparatus described above, in the plurality of polarizing members, the polarizing member having the wavelength characteristic of the extinction ratio in the relatively long wavelength region is the polarized light having the wavelength property of the extinction ratio in the relatively short wavelength region. It is preferable to be arranged on the light source side of the member.

  At this time, it is preferable that the first polarizing element includes the plurality of polarizing members.

  According to the present invention, inspection with higher sensitivity can be performed.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, the surface inspection apparatus 1 of the present embodiment includes a stage 20 that supports a semiconductor wafer 10 (hereinafter referred to as a wafer 10) that is a substrate to be tested, an illumination optical system 30, and an imaging optical system 40. And the image processing apparatus 50. The surface inspection apparatus 1 is an apparatus that automatically inspects the surface of a wafer 10 in a manufacturing process of a semiconductor circuit element. After exposure / development of the uppermost resist film, the wafer 10 is carried from a wafer cassette (not shown) or a developing device by a conveyance system (not shown), and is sucked and held on the stage 20.

  As shown in FIG. 2, a plurality of chip regions 11 are arranged in the XY direction on the surface of the wafer 10, and a predetermined repetitive pattern 12 is formed in each chip region. As shown in FIG. 3, the repetitive pattern 12 is a resist pattern (for example, a wiring pattern) in which a plurality of line portions 2A are arranged at a constant pitch P along the short direction (X direction). Between adjacent line parts 2A is a space part 2B. The arrangement direction (X direction) of the line portions 2A is referred to as “repeating direction of the repeating pattern 12”.

Here, the design value of the line width D _A of the line portion 2A in the repetitive pattern 12 and 1/2 of the pitch P. That is, the repetitive pattern 12 has a concavo-convex shape in which the line portions 2A and the space portions 2B are alternately arranged along the X direction. line width D _B of the line width D _a and the space portion 2B of 2A are equal, the volume ratio of the line portion 2A and the space portion 2B is substantially 1: 1. In the case of such an ideal shape, the light amount (light intensity) of the polarization component detected by the imaging optical system 40 described later is the largest. In contrast, when the exposure focus deviates from an appropriate value, the pitch P does not change, with the line width D _A of the line portion 2A becomes different from a design value, becomes different even with the line width D _B of the space portion 2B, The volume ratio between the line portion 2A and the space portion 2B deviates from about 1: 1. At this time, the amount of light of the polarization component is smaller than in the ideal case. Further, when the in-focus state is deviated from proper, the volume ratio between the line portion 2A and the space portion 2B does not change, the linearity of the edge portion of the pattern is lost, and the edge shape is disturbed.

  The surface inspection apparatus 1 according to the present embodiment uses the change in the volume ratio between the line portion 2A and the space portion 2B in the repetitive pattern 12 as described above or the disorder in the shape of the pattern edge portion to detect abnormalities in the repetitive pattern 12. The presence or absence is inspected. Defects as described above appear for each shot area of the wafer 10.

  In the present embodiment, it is assumed that the pitch P of the repeating pattern 12 is sufficiently small compared to the wavelength of illumination light (linearly polarized light described later) with respect to the repeating pattern 12. For this reason, diffracted light is not generated from the repetitive pattern 12, and the inspection of the repetitive pattern 12 cannot be performed by diffracted light.

  The stage 20 of the surface inspection apparatus 1 supports the wafer 10 on the upper surface and fixes and holds the wafer 10 by, for example, vacuum suction. Further, the stage 20 is rotatable about a normal line at the center of the upper surface of the stage as a central axis. By this rotation mechanism, the repeating direction of the repeating pattern 12 on the wafer 10 (the X direction in FIGS. 2 and 3) can be rotated within the surface of the wafer 10.

  In the present embodiment, in order to maximize the inspection sensitivity of the repetitive pattern 12, the repetitive direction of the repetitive pattern 12 on the wafer 10 is changed to the illumination light (linearly polarized light L) on the surface of the wafer 10 as shown in FIG. It is set at an angle of 45 degrees with respect to the vibration direction. The angle is not limited to 45 degrees, and can be set in an arbitrary angle direction such as 22.5 degrees or 67.5 degrees.

  As shown in FIG. 1, the illumination optical system 30 includes an illumination device 31 that emits light having a specific wavelength, a first polarizing element 33, and a first concave reflecting mirror 38. . The first polarizing element 33 is disposed on the optical path between the illumination device 31 and the first concave reflecting mirror 38, and linearly polarized light L (in accordance with the direction of the transmission axis) is emitted from the illumination device 31. Refer to FIG. The first polarizing element 33 is arranged in order from the illumination device 31 side, the first visible light polarizing member 34, the first i-line polarizing member 35, and the first j-ray polarizing member 36. The three polarizing members 34 to 36 are arranged so that their transmission axes have the same direction and are adjacent to each other.

  The first visible light polarizing member 34 is a polarizing cube beam splitter, and extracts p-polarized light from the light from the illumination device 31 and transmits it to the first concave reflecting mirror 38. In addition, the first visible light polarizing member 34 has visible light such as e-ray (wavelength λ = 546 nm), g-ray (wavelength λ = 436 nm), and h-ray (wavelength λ = 405 nm) as illumination light (linearly polarized light). At this time, the extinction ratio is set to be the maximum, and is arranged so that it can be inserted into and removed from the optical path between the illumination device 31 and the first concave reflecting mirror 38 by a driving device (not shown).

  The first i-line polarizing member 35 is a polarizing cube beam splitter, extracts p-polarized light from the light from the illumination device 31 and transmits the p-polarized light to the first concave reflecting mirror 38. The first i-line polarizing member 35 is set so that the extinction ratio is maximized when the illumination light (linearly polarized light) is i-line (wavelength λ = 365 nm). It is arranged on the optical path between the illumination device 31 and the first concave reflecting mirror 38 so as to be insertable / removable.

  The first j-ray polarization member 36 is a polarization cube beam splitter, extracts p-polarized light from the light from the illumination device 31 and transmits the p-polarized light to the first concave reflecting mirror 38. The first j-ray polarizing member 36 is set so that the extinction ratio is maximized when the illumination light (linearly polarized light) is j-ray (wavelength λ = 313 nm). It is arranged on the optical path between the illumination device 31 and the first concave reflecting mirror 38 so as to be insertable / removable.

  The first concave reflecting mirror 38 is a reflecting mirror having a spherical inner surface as a reflecting surface, so that the front focal point substantially coincides with the exit end of the illumination device 31 and the rear focal point substantially coincides with the surface of the wafer 10. , Is disposed obliquely above the stage 20. Then, the first concave reflecting mirror 38 converts the light from the first polarizing element 33 reflected by the first concave reflecting mirror 38 into a parallel light beam and irradiates the wafer 10 which is a test substrate. That is, the illumination optical system 30 is an optical system telecentric with respect to the wafer 10 side. Note that the optical axis of the illumination optical system 30 closer to the wafer 10 than the first concave reflecting mirror 38 is tilted by a predetermined incident angle with respect to the normal line of the stage 20.

  In the illumination optical system 30, the light from the illumination device 31 becomes p-polarized linearly polarized light L via the first polarizing element 33 and the first concave reflecting mirror 38, and is applied to the entire surface of the wafer 10 as illumination light. Incident. At this time, the traveling direction of the linearly polarized light L (the direction of the principal ray of the linearly polarized light L reaching an arbitrary point on the surface of the wafer 10) is substantially parallel to the optical axis. Are equal to each other because of the parallel light flux.

  In this embodiment, since the linearly polarized light L incident on the wafer 10 is p-polarized light, the repeating direction of the repeated pattern 12 is the incident surface of the linearly polarized light L (linearly polarized light on the surface of the wafer 10) as shown in FIG. When the angle is set to 45 degrees with respect to the L traveling direction), the angle formed by the vibration direction of the linearly polarized light L on the surface of the wafer 10 and the repeating direction of the repeating pattern 12 is also set to 45 degrees. In other words, the linearly polarized light L changes into the repeated pattern 12 so as to cross the repeated pattern 12 diagonally with the vibration direction of the linearly polarized light L on the surface of the wafer 10 inclined by 45 degrees with respect to the repeated direction of the repeated pattern 12. It will be incident.

  As shown in FIG. 1, the imaging optical system 40 includes a second concave reflecting mirror 41, a second polarizing element 43, and an imaging device 48, and the optical axis thereof is centered on the stage 20. It is disposed so as to be inclined to the opposite side by the same angle as the incident angle with respect to the normal passing therethrough. Therefore, the specularly reflected light that is specularly reflected on the surface of the wafer 10 (repeated pattern 12) travels along the optical axis of the imaging optical system 40. The second concave reflecting mirror 41 is a reflecting mirror similar to the first concave reflecting mirror 38, and the specularly reflected light from the wafer 10 is reflected by the second concave reflecting mirror 41 and collected, and the second The polarizing element 43 passes through the polarizing element 43 and reaches the imaging surface of the imaging device 48 to form an image of the wafer 10.

  The second polarizing element 43 is disposed on the optical path between the second concave reflecting mirror 41 and the imaging device 48, and the direction of the transmission axis of the second polarizing element 43 is determined by the illumination optical system 30 described above. It is set to be orthogonal to the transmission axis of the first polarizing element 33 (in a crossed Nicol state). Accordingly, the second polarizing element 43 extracts a polarization component (for example, an s-polarized component) whose vibration direction is substantially perpendicular to the linearly polarized light L from the regular reflected light from the wafer 10 (repeated pattern 12), and performs imaging. Device 48 can be directed. As a result, a reflected image of the wafer 10 is formed on the image pickup surface of the image pickup device 48 by using a polarized light component whose vibration direction is substantially perpendicular to the linearly polarized light L of the regular reflection light from the wafer 10. The second polarizing element 43 includes a second j-ray polarizing member 46, a second i-ray polarizing member 45, and a second visible light, which are arranged in order from the second concave reflecting mirror 41 side. The three polarizing members 44 to 46 are arranged so that the directions of the transmission axes are the same and are adjacent to each other. The first polarizing element 33 and the second polarizing element 43 may be shifted, for example, several degrees from the crossed Nicols state.

  The second j-ray polarizing member 46 is a polarizing cube beam splitter, and extracts a polarized light component (s-polarized light component) whose vibration direction is substantially perpendicular to the linearly polarized light L from the light from the second concave reflecting mirror 41. To the imaging device 48. The second j-ray polarizing member 46 is set so that the extinction ratio is maximized when the illumination light (linearly polarized light) is j-ray (wavelength λ = 313 nm). It is arranged on the optical path between the second concave reflecting mirror 41 and the imaging device 48 so that it can be inserted and removed.

  The second i-line polarizing member 45 is a polarizing cube beam splitter, and extracts the polarized light component (s-polarized light component) whose vibration direction is substantially perpendicular to the linearly polarized light L from the light from the second concave reflecting mirror 41. To the imaging device 48. The second i-line polarizing member 45 is set so that the extinction ratio is maximized when the illumination light (linearly polarized light) is i-line (wavelength λ = 365 nm). It is arranged on the optical path between the second concave reflecting mirror 41 and the imaging device 48 so that it can be inserted and removed.

  The second visible light polarizing member 44 is a polarizing cube beam splitter, and extracts the polarized light component (s-polarized light component) whose vibration direction is substantially perpendicular to the linearly polarized light L from the light from the second concave reflecting mirror 41. To the imaging device 48. Further, the second visible light polarizing member 44 has illumination light (linearly polarized light) such as e-ray (wavelength λ = 546 nm), g-ray (wavelength λ = 436 nm), and h-ray (wavelength λ = 405 nm). At this time, the extinction ratio is set to be maximum, and the extinction ratio is detachably disposed on the optical path between the second concave reflecting mirror 41 and the imaging device 48 by a driving device (not shown).

  The imaging device 48 is composed of, for example, a CCD imaging device, etc., photoelectrically converts the reflected image of the wafer 10 formed on the imaging surface, and outputs an image signal to the image processing device 50. The brightness and darkness of the reflected image of the wafer 10 is approximately proportional to the light amount (light intensity) of the polarization component detected by the imaging device 48 and changes according to the shape of the repeated pattern 12. The reflected image of the wafer 10 is brightest when the repeated pattern 12 has an ideal shape. The brightness of the reflected image of the wafer 10 appears for each shot area.

  The image processing device 50 captures a reflected image of the wafer 10 based on the image signal output from the imaging device 48. Note that the image processing apparatus 50 stores a reflection image of a non-defective wafer in advance for comparison. A non-defective wafer is one in which the repetitive pattern 12 is formed on the entire surface in an ideal shape. Therefore, it is considered that the luminance information (signal intensity) of the reflected image of the non-defective wafer indicates the highest luminance value.

  Therefore, when the image processing apparatus 50 captures the reflection image of the wafer 10 as the test substrate, the image processing apparatus 50 compares the luminance information (signal intensity) with the luminance information (signal intensity) of the reflection image of the non-defective wafer. Then, the abnormality of the repeated pattern 12 is detected based on the amount of decrease in the luminance value of the dark portion in the reflected image of the wafer 10. For example, if the light amount change is larger than a predetermined threshold (allowable value), it is determined as “abnormal”, and if it is smaller than the threshold, it is determined as “normal”. Then, the comparison result of the luminance information (signal intensity) by the image processing device 50 and the reflected image of the wafer 10 at that time are output and displayed on a monitor (not shown).

  As described above, the image processing apparatus 50 has a configuration in which the reflection image of the non-defective wafer is stored in advance and the array data of the shot area of the wafer 10 and the threshold value of the brightness value are stored in advance. Good. In this case, since the position of each shot area in the reflected image of the captured wafer 10 is known based on the array data of the shot area, the luminance value of each shot area is obtained. Then, the abnormality of the pattern is detected by comparing the luminance value with the stored threshold value. A shot area having a luminance value smaller than the threshold value may be determined as “abnormal”.

  In the surface inspection apparatus 1 configured as described above, light from the illumination device 31 becomes p-polarized linearly polarized light L via the first polarizing element 33 and the first concave reflecting mirror 38, and the wafer is used as illumination light. 10 is incident on the entire surface. The specularly reflected light that has been specularly reflected by the surface of the wafer 10 (repeated pattern 12) is reflected and collected by the second concave reflecting mirror 41, and reaches the imaging surface of the imaging device 48 via the second polarizing element 43. An image of the wafer 10 is formed.

  At this time, the polarization state of the linearly polarized light L changes due to the structural birefringence in the repeated pattern 12, and the second polarizing element 43 vibrates with the linearly polarized light L of the regular reflected light from the wafer 10 (repeated pattern 12). A polarized component (for example, an s-polarized component) whose directions are substantially perpendicular can be extracted and guided to the imaging device 48. As a result, a reflected image of the wafer 10 is formed on the image pickup surface of the image pickup device 48 by using a polarized light component whose vibration direction is substantially perpendicular to the linearly polarized light L of the regular reflection light from the wafer 10.

  Therefore, the imaging device 48 photoelectrically converts the reflected image of the wafer 10 formed on the imaging surface and outputs an image signal to the image processing device 50. The image processing device 50 outputs the image signal output from the imaging device 48. Based on the above, the reflection image of the wafer 10 is captured. When the reflected image of the wafer 10 is captured, the image processing apparatus 50 compares the luminance information (signal intensity) with the luminance information (signal intensity) of the reflected image of the non-defective wafer, and detects an abnormality of the repeated pattern 12. Then, the inspection result of the repeated pattern 12 by the image processing apparatus 50 and the reflected image of the wafer 10 at that time are output and displayed on a monitor (not shown).

  By the way, as described above, the first and second polarizing members for visible light 34 and 44 have the maximum extinction ratio when the illumination light (linearly polarized light) is visible light such as e-line, g-line, and h-line. However, as shown in FIG. 8, there is a slight extinction ratio even in the case of i-line, which is an adjacent wavelength region. The first and second i-line polarizing members 35 and 45 are set so that the extinction ratio is maximized when the illumination light (linearly polarized light) is i-line, but in the adjacent wavelength region. Some h-line and j-line also have a slight extinction ratio. The first and second j-ray polarizing members 36 and 46 are set so that the extinction ratio is maximized when the illumination light (linearly polarized light) is j-ray, but in the adjacent wavelength range. Even for a certain i-line, it has a slight extinction ratio.

  The inventor of the present application arranges a polarizing member having a wavelength characteristic of the extinction ratio close to a polarizing member having the maximum extinction ratio in a predetermined wavelength region (that is, arranges the polarizing member in the optical path along the optical path). ) If used, it has been found that since the polarizing member has a slight extinction ratio even in the wavelength region in which the polarizing member is close, the slight extinction ratio is added to improve the overall extinction ratio. Therefore, in this embodiment, when i-line is used as illumination light (linearly polarized light), as shown in FIG. 5, the first and second visible light polarizing members 34 and 44, and the first and second The i-line polarizing members 35 and 45 and the first and second j-ray polarizing members 36 and 46 are inserted into the optical path, respectively. As a result, the extinction ratio of the i-line of the i-line polarizing members 35 and 45 is added to the i-line extinction ratio of the i-line of the visible light polarizing members 34 and 44 and the j-ray polarizing members 36 and 46. The extinction ratio of the entire polarizing element with respect to the line can be improved.

  Further, when h-line (visible light) is used as illumination light (linearly polarized light), as shown in FIG. 6, the first and second visible light polarizing members 34 and 44 and the first and second i-line are used. The polarizing members 35 and 45 are inserted into the optical path, and the first and second j-ray polarizing members 36 and 46 are extracted from the optical path. As a result, the extinction ratio of the h-line of the i-line polarization members 35 and 45 is added to the extinction ratio of the h-line of the visible light polarization members 34 and 44, and the extinction ratio of the entire polarizing element with respect to the h-line. Can be improved. When j-rays are used as illumination light (linearly polarized light), as shown in FIG. 7, the first and second i-line polarizing members 35 and 45 and the first and second j-ray polarizing members 36 are used. , 46 are inserted into the optical path, and the first and second visible light polarizing members 34, 44 are extracted from the optical path. As a result, the extinction ratio of the j-line of the i-line polarizing members 35 and 45 is added to the extinction ratio of the j-line of the first and second j-ray polarizing members 36 and 46, and the polarization with respect to the j-line. The extinction ratio of the entire device can be improved. In addition, when using e line or g line as illumination light (linearly polarized light), only the 1st and 2nd polarizing members 34 and 44 for visible light are each inserted on an optical path.

  Thus, according to this embodiment, the first polarizing element 33 and the second polarizing element 43 have a plurality of polarizing members that are arranged side by side on the optical path and have different wavelength characteristics of extinction ratios. Therefore, the extinction ratios of the respective polarizing members are respectively added, so that a high extinction ratio can be obtained in each of the polarizing elements 33 and 43, and a more sensitive inspection can be performed.

  At this time, since the wavelength characteristics of the extinction ratio in each polarization member are close to each other, each polarization member has an extinction ratio in a wavelength range of a certain width. Each ratio can be added to effectively improve the extinction ratio.

  In addition, since each polarizing member is a polarizing cube beam splitter, the extinction ratio of each polarizing element 33, 43 can be obtained by adding the extinction ratio of each polarizing member by simply arranging the polarizing members. . Further, the polarizing member is gradually deteriorated by the action of light when used for a long time. In the above-described embodiment, the long-wavelength polarizing member is used for the short wavelength because the long-wavelength polarizing member and the short-wavelength polarizing member are arranged in this order from the side closer to the light source in the illumination-side optical system with strong light intensity. Since it plays the role of protecting the polarizing member, it is possible to prevent the deterioration of the expensive short wavelength polarizing member.

  In the above-described embodiment, the first polarizing element 33 and the second polarizing element 43 are configured to include a plurality of polarizing members arranged side by side on the optical path. However, the present invention is not limited to this. Even when only one of the first polarizing element 33 and the second polarizing element 43 has a plurality of polarizing members, the same effect can be obtained.

  In the above-described embodiment, the first polarizing element 33 and the second polarizing element 43 include the visible light polarizing members 34 and 44, the i-line polarizing members 35 and 45, and the j-ray polarizing member 36, 46, but is not limited to this, for example, a polarizing member having a maximum extinction ratio at a wavelength of 248 nm may be used, depending on the wavelength of illumination light to be used, A combination of other wavelengths (polarizing members) may be used.

  In the above-described embodiment, the imaging device 48 detects the reflected image of the wafer 10. However, the present invention is not limited to this, and the luminance distribution (Fourier image) on the pupil plane of the imaging optical system 40 is detected. The present invention can also be applied to an inspection apparatus that inspects the surface of the wafer 10.

It is a figure showing the whole surface inspection device composition concerning this embodiment. It is an external view of the surface of a semiconductor wafer. It is a perspective view explaining the uneven structure of a repeating pattern. It is a figure explaining the inclination state of the entrance plane of a linearly polarized light and the repeating direction of a repeating pattern. It is a perspective view which shows a polarizing element in the case of using i line | wire as illumination light. It is a perspective view which shows a polarizing element in the case of using visible light as illumination light. It is a perspective view which shows a polarizing element in the case of using j line as illumination light. It is a figure which shows the relationship between the extinction ratio and wavelength in three types of polarizing members.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Surface inspection apparatus 10 Wafer (substrate to be tested) 12 Repeat pattern 30 Illumination optical system (illumination part) 31 Illumination apparatus (light source)
33 first polarizing element 34 first polarizing member for visible light 35 first polarizing member for i-line 36 first polarizing member for j-line 40 imaging optical system (detection unit)
43 2nd polarizing element 44 2nd polarizing member for visible light 45 2nd polarizing member for i line 46 46 2nd polarizing member for j line 50 Image processing apparatus (inspection part)
L Linearly polarized light

Claims (5)

An illumination unit for irradiating polarized light on the surface of the test substrate;
A detection unit for detecting reflected light from the surface of the test substrate irradiated with the polarized light;
An inspection unit that inspects the surface of the test substrate based on the light detected by the detection unit;
The illumination unit includes a first polarizing element that converts light from a light source into the polarized light, and irradiates the surface of the test substrate with the polarized light obtained by transmitting the first polarizing element from the light source. Configured to
The detection unit includes a second polarizing element disposed so that a direction intersecting a polarization direction of the polarized light polarized by the first polarizing element is a polarization direction, and the polarized light is irradiated It is configured to detect light obtained through the second polarizing element from the surface of the test substrate,
At least one of the first polarizing element and the second polarizing element has a plurality of polarizing members disposed in the optical path along the optical path and having different extinction ratio wavelength characteristics. A surface inspection apparatus characterized by that.   The surface inspection apparatus according to claim 1, wherein wavelength characteristics of extinction ratios of the plurality of polarizing members are close to each other.   The surface inspection apparatus according to claim 1, wherein the polarizing member is a polarizing cube beam splitter.   In the plurality of polarizing members, the polarizing member having an extinction ratio wavelength characteristic in a relatively long wavelength region is disposed closer to the light source than the polarizing member having an extinction ratio wavelength property in the relatively short wavelength region. The surface inspection apparatus according to any one of claims 1 to 3, wherein   The surface inspection apparatus according to claim 4, wherein the first polarizing element includes the plurality of polarizing members.

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