JP4506723B2 - Surface inspection device - Google Patents

Description

  The present invention relates to a surface inspection apparatus that performs defect inspection of a repetitive pattern formed on a surface of a substrate to be tested.

An apparatus that irradiates a repetitive pattern formed on the surface of a substrate to be tested (for example, a semiconductor wafer or a liquid crystal substrate) with inspection illumination light, and then inspects the defect of the repetitive pattern based on the light generated from the repetitive pattern. It has been known.
There has also been proposed an apparatus that uses linearly polarized light as illumination light for inspection and receives a component related to a change in polarization state in the repetitive pattern out of light generated from the repetitive pattern, and performs defect inspection (for example, (See Patent Document 1). In this apparatus, in order to perform highly sensitive defect inspection, the direction of linearly polarized light of illumination light is set to a direction of 45 degrees with respect to the repeating direction of the repeating pattern.
International Publication No. 2005/040776 Pamphlet

However, in the above apparatus, if the direction of the repeated pattern to be inspected is not known in advance, the direction of the linearly polarized light of the illumination light cannot be set to a 45 degree direction, and a highly sensitive defect inspection is performed. I could not.
An object of the present invention is to provide a surface inspection apparatus that can perform a highly sensitive defect inspection even if the direction of a repetitive pattern is not known in advance.

The surface inspection apparatus of the present invention comprises an illuminating means for illuminating a repetitive pattern formed on the surface of a substrate to be tested with linearly polarized light, a direction of the vibration surface of the linearly polarized light on the surface, and a repetitive direction of the repetitive pattern. Setting means for sequentially setting the angle to a plurality of different angles based on the outer shape reference of the substrate to be tested , and among the specularly reflected light generated from the repetitive pattern in each state set to the angle sequentially, The repeating pattern is extracted by using a measuring means for taking out the polarization component orthogonal to the vibration plane of the linearly polarized light and measuring the light intensity of the extracted polarization component , and using the maximum value among the light intensities measured in the respective states. And detecting means for detecting the defect.

Another surface inspection apparatus of the present invention includes an illumination unit that illuminates a repetitive pattern formed on the surface of a substrate to be tested with linearly polarized light, a direction of the linearly polarized vibration surface on the surface, and a repetitive direction of the repetitive pattern. The setting means for sequentially setting the angle formed by a plurality of different angles based on the outer shape reference of the substrate to be tested , and the specularly reflected light generated from the repetitive pattern in each state set to the angle sequentially Among these, the brightest image among the images captured in each state, and a processing means for extracting a polarization component orthogonal to the plane of vibration of the linearly polarized light and capturing the image of the test substrate using the extracted polarization component And detecting means for detecting a defect of the repetitive pattern using each pixel value.

  According to the surface inspection apparatus of the present invention, a highly sensitive defect inspection can be performed even if the direction of the repeated pattern is not known in advance.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1, the surface inspection apparatus 10 according to the present embodiment includes a stage 11 that supports a test substrate 20, an alignment system 12, an illumination system 13, a light receiving system 14, and an image processing unit 15. The The surface inspection apparatus 10 of this embodiment is a batch imaging type apparatus.
The test substrate 20 is, for example, a semiconductor wafer or a liquid crystal glass substrate. As shown in FIG. 2, a repeated pattern 22 to be inspected is formed at each point on the surface (resist layer) of the test substrate 20. The repeating pattern 22 is a wiring pattern or the like. The arrangement direction (X direction) of the line portions of the repetitive pattern 22 is referred to as “repetitive direction of the repetitive pattern 22”.

  The surface inspection apparatus 10 according to this embodiment is an apparatus that automatically performs a defect inspection of a repetitive pattern 22 formed on the surface of a substrate 20 to be tested in a manufacturing process of a semiconductor circuit element or a liquid crystal display element. The defect of the repetitive pattern 22 is a change in shape such as a defocus defect at the time of exposure on the test substrate 20, a resist film thickness unevenness, or a scratch. After exposure / development on the surface (resist layer), the test substrate 20 is conveyed from the cassette or the developing device by a conveyance system (not shown) and is attracted to the stage 11.

  The stage 11 places the test substrate 20 on the upper surface and fixes and holds it, for example, by vacuum suction. The stage 11 is provided with a rotation mechanism (not shown), and the rotation axis is perpendicular to the upper surface on which the substrate 20 to be tested is placed. The stage 11 is rotated by the rotation mechanism, and the test substrate 20 placed on the upper surface of the stage 11 is rotated, so that the repetitive direction (X direction in FIG. 2) of the repetitive pattern 22 is changed within the surface of the test substrate 20. Can be rotated.

During such rotation, the alignment system 12 illuminates the outer edge of the substrate 20 to be tested, and based on the position in the rotation direction of an external reference (notch) (not shown) provided on the outer edge. The direction of the test substrate 20 is detected. Then, when the test substrate 20 is in a desired direction, the rotation of the stage 11 is stopped.
At this time, the repetitive direction (X direction) of the repetitive pattern 22 formed on the surface of the test substrate 20 is any one of various directions shown in FIGS. 3A to 3C, for example. It is not always possible to grasp. This is because the direction (X direction) of the repeated pattern 22 may be different for each layer (each process) on the surface of the test substrate 20.

  The illumination system 13 is a means for irradiating the inspection illumination light L1 to the repetitive pattern 22 (see FIGS. 3A to 3C) on the surface of the substrate 20 to be tested. It comprises a filter 32, a light guide fiber 33, a polarizing filter 34, and a concave reflecting mirror 35 (decentered optical system). The illumination system 13 is an optical system telecentric with respect to the test substrate 20 side.

  The light source 31 is an inexpensive discharge light source such as a halogen lamp, a metal halide lamp, or a mercury lamp. For example, when the light source 31 is a mercury lamp, the wavelength range of the light emitted from the light source 31 is about 240 nm to 600 nm, and includes the region from the ultraviolet range to the visible range. The wavelength selection filter 32 selectively transmits an emission line spectrum (narrow band spectrum) of a predetermined wavelength in the light emitted from the light source 31.

The light guide fiber 33 transmits light emitted from the wavelength selection filter 32 and emits illumination light L0 (unpolarized light) of a divergent light beam. The spreading angle of the illumination light L0 of the divergent light beam is an angle corresponding to the numerical aperture of the light guide fiber 33.
The polarizing filter 34 is disposed in the vicinity of the exit end of the light guide fiber 33, and its transmission axis is set to a predetermined direction. Then, the illumination light L0 (non-polarized light) of the divergent light beam from the light guide fiber 33 is converted into a polarization state (that is, linearly polarized light) according to the direction of the transmission axis. For this reason, the diverging light beam L0 (linearly polarized light) is guided from the polarizing filter 34 to the concave reflecting mirror 35.

  The concave reflecting mirror 35 is a reflecting mirror having a spherical inner surface as a reflecting surface, and is arranged so that the front focal point substantially coincides with the exit end of the light guide fiber 33 and the rear focal point substantially coincides with the surface of the substrate 20 to be tested. Is done. Therefore, the illumination light L0 (linearly polarized light) of the divergent light beam from the polarization filter 34 is collimated by the concave reflecting mirror 35, and is irradiated onto the repetitive pattern 22 on the surface of the substrate 20 to be examined as the illumination light L1 for inspection of the parallel light beam. (So-called telecentric lighting).

At this time, the illumination light L1 for inspection can be incident on each point of a relatively wide region (for example, the entire region) of the surface of the substrate 20 to be examined from an obliquely upward direction under a substantially constant angle condition. By illuminating the entire surface of the substrate 20 to be tested, it is possible to detect the defects of the pattern 22 all over the surface, and to perform defect inspection with high throughput.
In the defect inspection of the repeated pattern 22, the test substrate 20 is set in a desired direction (for example, the state shown in FIG. 3A), and then the test substrate 20 is rotated stepwise. Then, as shown in FIGS. 4A to 4C, an angle formed by the direction of the vibration surface (V direction) of the illumination light L1 on the surface of the test substrate 20 and the repeating direction (X direction) of the repeating pattern 22. Are set to a plurality of different oblique angles φ, φ + Δ, φ + 2Δ,. Such an angular relationship between the illumination light L1 and the repeated pattern 22 is substantially uniform over the entire surface of the test substrate 20.

Then, when the repeated pattern 22 is illuminated using the illumination light L1 (linearly polarized light), the polarization state of the linearly polarized light (illuminated light L1) due to structural birefringence caused by the anisotropy of the repeated pattern 22 Changes, and the elliptically polarized specularly reflected light L2 (FIG. 1) is generated from the repeated pattern 22 along the incident surface at each point.
Details of the ellipticalization of linearly polarized light by the structural birefringence of the repetitive pattern 22 are described in the pamphlet of International Publication No. 2005/040776 already filed by the present applicant, and thus detailed description thereof is omitted here.

In the present embodiment, since the pitch (for example, 110 nm) of the repeated pattern 22 is sufficiently smaller than the wavelength of the illumination light L1 (wavelength range of about 240 nm to 600 nm), the repetition pattern 22 is repeated when the illumination light L1 is irradiated. Diffracted light is not generated from the pattern 22.
The surface inspection apparatus 10 of the present embodiment illuminates the repetitive pattern 22 on the surface of the test substrate 20 with linearly polarized illumination light L1 (FIG. 4), and at this time the elliptically polarized regular reflection light L2 generated from the repetitive pattern 22 Is guided to the light receiving system 14, and the defect inspection of the repeated pattern 22 is performed based on the polarization state (that is, the degree of ovalization).

The light receiving system 14 (FIG. 1) is a means for outputting a light receiving signal based on the regular reflection light L2 generated from the repetitive pattern 22, and includes a concave reflecting mirror 36, a polarizing filter 37, a condensing lens 38, and an imaging. And an element 39 (decentered optical system). Similarly to the illumination system 13, the light receiving system 14 is also an optical system telecentric with respect to the test substrate 20 side.
The concave reflecting mirror 36 has the same configuration as the concave reflecting mirror 35 of the illumination system 13, and reflects the specularly reflected light L2 generated from the repetitive pattern 22 on the surface of the substrate 20 to be examined, thereby collecting the condensed light beam (specularly reflected light L3). ) And led to the polarizing filter 37. A part (L 4) of the light (L 3) from the concave reflecting mirror 36 passes through the polarizing filter 37 and then enters the imaging surface of the imaging device 39 through the condenser lens 38.

The polarizing filter 37 is disposed in the vicinity of the condenser lens 38, and its transmission axis is set to a predetermined orientation. The direction of the transmission axis of the polarizing filter 37 is arranged so that the respective transmission axes are orthogonal to the polarizing filter 34 of the illumination system 13 (crossed Nicol arrangement).
For this reason, when the light (L3) from the concave reflecting mirror 36 is transmitted through the polarizing filter 37, the polarized light component L4 corresponding to the direction of its transmission axis (that is, polarized light perpendicular to the vibrating surface of the linearly polarized illumination light L1). Only component) is extracted. This polarization component L4 has a magnitude corresponding to the polarization state of the elliptically polarized specularly reflected light L2 generated from the repeated pattern 22 (that is, the degree of ovalization).

Note that, in the portion of the surface of the test substrate 20 where the repeated pattern 22 is not present, the size of the polarization component L4 becomes almost 0 (dark field). On the other hand, in the repetitive pattern 22, the linearly polarized light (L1) becomes elliptically polarized light (L2) due to structural birefringence, and the polarization component L4 has a finite value, so that the pattern image appears in the dark field. Will be seen.
The polarization component L4 from the polarization filter 37 is incident on the imaging surface of the imaging device 39 via the condenser lens 38. At this time, a reflection image of the surface of the test substrate 20 is formed on the imaging surface of the imaging device 39 by the polarization component L4. The imaging element 39 is disposed at a position conjugate with the surface of the substrate 20 to be tested via the concave reflecting mirror 36 and the condenser lens 38. The image pickup device 39 is, for example, a CCD image pickup device or the like, photoelectrically converts a reflection image of the surface of the test substrate 20 formed on the image pickup surface, and outputs a light reception signal for each pixel to the image processing unit 15.

The image processing unit 15 captures a reflected image of the test substrate 20 based on the light reception signal output from the image sensor 39. In this reflected image, light and dark depending on the polarization state of the regular reflection light L2 (that is, the magnitude of the polarization component L4) generated from each point (repetitive pattern 22) on the surface of the test substrate 20 appears.
When the image processing unit 15 captures the reflection image of the test substrate 20, the image processing unit 15 compares the luminance information with the luminance information of the reflection image of the non-defective sample, for example. A non-defective sample is a sample in which a repetitive pattern 22 having an ideal shape and having no defects is formed on the entire surface.

The image processing unit 15 measures the amount of change in the luminance value of the reflected image of the test substrate 20 with reference to the luminance value of the reflected image of the non-defective sample. The amount of change in the luminance value obtained is a change in the polarization state (that is, the magnitude of the polarization component L4) of the regular reflection light L2 due to the shape change of the repeated pattern 22 (defocus defect during exposure, film thickness unevenness of the resist, etc.). Represents.
Then, the image processing unit 15 detects a defect in the repetitive pattern 22 based on the amount of change in luminance value in the reflected image of the test substrate 20. For example, if the amount of change in luminance value is larger than a predetermined threshold (allowable value), it is determined as “defect”, and if it is smaller than the threshold, it is determined as “normal”. In addition, the amount of change in the luminance value in the reflected image of the test substrate 20 may be compared with a predetermined threshold without using a non-defective sample.

  In this way, the repetitive pattern 22 is illuminated by the linearly polarized illumination light L1, and the reflected image of the test substrate 20 according to the polarization state of the specularly reflected light L2 generated from the repetitive pattern 22 (that is, the magnitude of the polarization component L4). When the defect of the repeated pattern 22 is detected based on the brightness of the reflected image, the direction of the vibration surface of the illumination light L1 (for example, the V direction in FIG. 4) is repeated in order to perform a highly sensitive defect inspection. It is said that the angle formed with the repeating direction (X direction) of the pattern 22 may be set to 45 degrees (state shown in FIG. 5).

Here, for example, as shown in FIG. 4A, the angle formed by the direction of the vibrating surface (V direction) of the illumination light L1 and the repeating direction of the repeating pattern 22 (X direction) is an oblique angle φ. (0 degree <φ <90 degrees), the magnitude of the polarization component L4 (light intensity I _L4 ) is expressed by the following equation (1).
^{_{I L4 = (E L4) 2}} = E 2/4 · (γ X -γ Y) 2 · sin 2 (2φ) ... (1)
In Equation (1), E _L4 is the amplitude of the polarization component L4, E is the amplitude of the illumination light L1, γ _X is the amplitude reflectivity in the repeating direction (X direction) of the repeating pattern 22, and γ _Y is the repeating direction (X direction). Amplitude reflectivity in a direction perpendicular to (Y direction).

In order to derive the expression (1), when the specularly reflected light L2 is divided into a component parallel to the repeating direction (X direction) of the repeating pattern 22 and a component perpendicular to the repeating pattern 22, it is perpendicular to the amplitude E _X ′ of the parallel component. The amplitude E _Y ′ of each component (FIG. 6A) is expressed by the following equations (2) and (3), respectively.
E _X '= γ _X · Ecosφ (2)
E _Y '= γ _Y · Esinφ (3)
Then, the amplitudes E _X ′ and E _Y ′ of each component of the regular reflection light L2 are projected onto the direction of the transmission axis of the polarizing filter 37 of the light receiving system 14 (FIG. 6B), and these are expressed by the following equation (4). Is added, the amplitude E _L4 of the polarization component _L4 is obtained. Furthermore, if the amplitude E _L4 is squared, the magnitude (light intensity I _L4 ) of the polarization component L4 in the equation (1) can be obtained.

E _L4 = E _X 'sinφ-E _Y ' cosφ = E / 2 ・ (γ _X −γ _Y ) ・ sin (2φ) (4)
In the expression (1), in the repetitive pattern 22 of the substrate 20 to be tested, the amplitude reflectances γ _X and γ _Y generally have different values due to structural birefringence, and this difference (γ _X −γ _Y ) This value is unique to the line and space of the repeated pattern 22.
From the equation (1), it can be seen that 2φ = 90 degrees (ie, φ = 45 degrees) is sufficient to detect the difference in amplitude reflectivity (γ _X −γ _Y ) (the state of FIG. 5). ). If the angle φ is set to 45 degrees, it is most susceptible to structural birefringence and the polarization component L4 is maximized. At this time, the magnitude of the polarization component L4 (light intensity I _{L4 (45} degrees ₎ ) is expressed as in Expression (5).

I _{L4 (45 ^{°) = E 2/4 · (}} γ X -γ Y) 2 ... (5)
If the repetitive direction (X direction) of the repetitive pattern 22 to be inspected is known in advance, the angle formed by this repetitive direction (X direction) and the direction of the vibration surface of the illumination light L1 (V direction) is 45 degrees. It can be set (state of FIG. 5), and a highly sensitive defect inspection can be performed. However, the direction (X direction) of the repetitive pattern 22 is not always grasped, and there is a possibility that it is not known in advance.

Therefore, in the surface inspection apparatus 10 of the present embodiment, in order to perform a highly sensitive defect inspection even if the direction (X direction) of the repeated pattern 22 is not known, a defect inspection process is performed according to the procedure of the flowchart of FIG. .
In step S1, the test substrate 20 is set in a desired direction (for example, the state shown in FIG. 3A). At this time, the angle formed by the direction of the vibration surface (V direction) of the illumination light L1 and the repeating direction (X direction) of the repeating pattern 22 is, for example, as shown in FIG. φ ≦ 90 degrees).

At this time, out of the regular reflection light L2 generated from the repetitive pattern 22, the polarization component L4 incident on the image pickup surface of the image pickup device 39 has its amplitude E _L4 (FIG. 6) expressed by the above equation (4), and light The intensity I _L4 is represented by the above formula (1).
Next (step S <b> 2), the state of the angle φ set in step S <b> 1 is maintained, and the reflected image of the test substrate 20 is taken into the image processing unit 15. Each pixel value of the reflected image captured at this time is proportional to the polarization state of the regular reflection light L2 generated from the repetitive pattern 22 (that is, the light intensity I _L4 of the polarization component L4 expressed by the equation (1)).

Next (step S3), the image processing unit 15 detects the brightness of the reflected image captured at the angle φ. The brightness of the reflected image is, for example, the intensity of one pixel corresponding to a predetermined point on the surface of the test substrate 20 (the light intensity I _L4 of the polarization component _L4 ), or the average value of the intensity of a plurality of pixels or all pixels. is there.
If the processes in steps S2 and S3 are the first time (No in step S4), the process in step S6 is performed without performing the process in step S5. In step S6, the current rotation angle of the stage 11 (for example, 0 degree), each pixel value of the reflected image, and each brightness data are stored.

Next (step S7), the stage 11 is rotated by a predetermined angle Δ (for example, 30 degrees), and as shown in FIG. 4B, the direction of the repetitive pattern 22 (X direction) and the vibration surface of the illumination light L1. The angle formed with the direction (V direction) is set to an angle (φ + Δ) different from the angle φ. The angle Δ may be appropriately selected (input) according to the accuracy required for defect inspection.
When such a rotation process (angle Δ) ends, the process returns to step S2. Then, the reflection image of the test substrate 20 is taken into the image processing unit 15 while maintaining the state of the angle (φ + Δ) (step S3), and the brightness (for example, average luminance) is detected. Then, since the process of this step S2 and S3 is the 2nd time (step S4 is Yes), it progresses to the process of step S5.

In step S5, the brightness of the current reflected image is compared with the brightness of the previous reflected image (data stored in step S6). As can be seen from the above equation (1), the brightness of the reflected image (the light intensity I _L4 of the polarization component _L4 ) is the direction of the repetitive pattern 22 (X direction) and the direction of the vibration surface of the illumination light L1 (V direction). Depends on the angle formed by and increases as it approaches 45 degrees.
Therefore, if the result of the comparison in step S5 is that the previous reflection image is darker (the current reflection image is brighter), the second angle (φ + Δ) is 45 degrees than the first angle φ. Therefore, the process proceeds to step S6. In step S6, the current rotation angle (angle Δ) of the stage 11, the reflected image, and the brightness data are overwritten and stored.

Next (step S7), similarly to the above, the stage 11 is further rotated by a predetermined angle Δ, and as shown in FIG. 4C, the direction of the repetitive pattern 22 (X direction) and the vibration surface of the illumination light L1. The angle formed with the direction (V direction) is set to an angle (φ + 2Δ) different from the angle φ and the angle (φ + Δ).
In this way, the processing of steps S2 to S7 is repeated, and if it is determined in step S5 that the previous reflection image is brighter (the current one is darker), the previous angle than the current angle (φ + nΔ). Since (φ + (n−1) Δ) is considered to be closer to 45 degrees, the process proceeds to step S8 without storing the current data.

  The latest data stored at this time is the previous data, and is captured at a plurality of different angles φ, (φ + Δ), (φ + 2Δ),..., (Φ + nΔ) while repeating the processing of steps S2 to S7. Among the reflected images, the brightest reflected image data. That is, the latest data is data of a reflection image captured at an angle closest to 45 degrees among a plurality of angles φ, (φ + Δ), (φ + 2Δ),..., (Φ + nΔ).

In step S8, the latest data stored at this time is read, and the defect of the repeated pattern 22 is detected based on each pixel value of the reflected image (that is, each pixel value of the brightest reflected image).
As described above, in the present embodiment, the angle formed between the direction of the repeated pattern 22 (X direction) and the direction of the vibration surface of the illumination light L1 (V direction) is set to a plurality of different angles φ, (φ + Δ),. (φ + nΔ) is set, a reflected image of the test substrate 20 is captured in each state, and a defect is detected from each pixel value of the brightest image among the images captured in each state.

Therefore, even if the direction (X direction) of the repetitive pattern 22 is not known in advance, the optimum angle formed by the direction of the repetitive pattern 22 (X direction) and the direction of the vibration surface of the illumination light L1 (V direction) is 45 degrees. The defect inspection can be performed with high sensitivity equivalent to the case of FIG. 5 set to 45 degrees.
The direction (X direction) of the repeated pattern 22 may be different for each layer (each process) on the surface of the substrate 20 to be tested, and cannot always be grasped. However, even in such a case, if the surface inspection apparatus 10 of this embodiment is used, the defect inspection of the repeated pattern 22 of all layers (all processes) can be performed with high sensitivity.

  When the number of repetitions (n + 1) of the processes in steps S2 to S7 in FIG. 7 and the single rotation angle Δ of the stage 11 are used, the cumulative rotation angle (scan range) from the initial state of the stage 11 is nΔ. It becomes. Then, the above-described process of FIG. 7 always ends after passing through the optimum 45 degrees before the cumulative rotation angle nΔ exceeds 90 degrees for the first time. For example, when Δ = 30 degrees, the process is completed by repeating the process (S2 to S7) within three times.

When Δ = 30 degrees, an image is captured in a range of ± 15 degrees with respect to the optimum 45 degrees, even if the direction (X direction) of the repetitive pattern 22 is not known in advance, and based on this image Defect inspection can be performed. As the one-time rotation angle Δ of the stage 11 is smaller, defect inspection under an optimum condition close to 45 degrees becomes possible. Even when Δ = 30 degrees, the defect inspection should be performed with sufficient sensitivity while ensuring a light intensity of about 70% or more of the optimum light intensity I _{L4 (45} degrees ₎ (Equation (5)) at ₄₅ degrees. Can do.

  Further, in the present embodiment, the reflected images of a relatively wide area (for example, the entire area) of the surface of the test substrate 20 are collectively displayed in each of a plurality of different angle states (for example, FIGS. 4A to 4C). Therefore, when estimating the angle closest to the optimum 45 degrees, since the overall brightness (average luminance) of the reflected image can be used as an index, the estimation accuracy is improved. In addition, the defect inspection of each part on the surface of the substrate 20 to be tested can be performed efficiently and with high sensitivity.

(Modification)
In the above-described embodiment, the direction of the repetitive pattern (such as the X direction) is rotated by the rotation of the stage 11, and the angle formed between the repetitive direction (such as the X direction) and the direction of the vibration surface of the illumination light L1 (the V direction). Although changed, the present invention is not limited to this. Instead of rotating the stage 11, the polarization filters 34 and 37 of the illumination system 13 and the light receiving system 14 are rotated, for example, about the optical axis, and the direction of the vibration surface (V direction) of the illumination light L1 is rotated to perform similar scanning. May be performed. Further, the rotation of the stage 11 and the rotation of the polarizing filters 34 and 37 may be combined. When rotating the polarizing filters 34 and 37, it is preferable to rotate them in synchronization with each other while maintaining the angular relationship between the transmission axes (for example, the crossed Nicols state) constant.

In the above-described embodiment, the transmission axes of the polarizing filters 34 and 37 are orthogonal to each other to form a crossed Nicol arrangement, but the present invention is not limited to this. The transmission axes of the polarizing filters 34 and 37 may intersect at an angle other than orthogonal. However, the sensitivity of defect detection is highest when the polarizing filters 34 and 37 are arranged in a crossed Nicol arrangement.
Further, in the above-described embodiment, the example in which the reflection image of the test substrate 20 is captured and the defect inspection is performed has been described, but the present invention is not limited to this. Without capturing the reflection image of the test substrate 20, the light intensity I _L4 of the polarization component L4 of the regular reflection light L2 generated from each part of the surface of the test substrate 20 is measured, and each part of the test substrate 20 is defective. An inspection may be performed. In this case, in each state set to a plurality of different angles φ, (φ + Δ),..., (Φ + nΔ), the light intensity I _L4 of the polarization component L4 of the regular reflection light L2 is measured, and the obtained light in each state What is necessary is just to detect the defect of the repeating pattern 22 based on the maximum value among intensity _| strength _IL4 .

  Further, in the above-described embodiment, the step angle (the above-described angle Δ) is constant during scanning by rotating the stage 11 and / or the polarization filters 34 and 37, but the present invention is not limited to this. The step angle may be changed in the middle of scanning, and a wide range may be scanned with a rough step angle at first, and after pursuing a narrow range including an optimum 45 degrees, this narrow range may be scanned with a fine step angle.

Furthermore, although the above-described embodiment has been described on the assumption that the repeated pattern 22 in the same direction is formed on the entire surface of the substrate 20 to be tested, the present invention is not limited to this. The present invention can also be applied to the case where various repeating directions X _{1 to} X ₃ (for example, FIG. 8) exist on the surface of the test substrate 20. In this case, processing may be performed individually for each repeated pattern to perform an optimal defect inspection at 45 degrees, or the region may be divided for each repeated pattern in the same repeating direction and processed for each region. In addition, an optimum defect inspection at 45 degrees may be performed.

1 is a diagram illustrating an overall configuration of a surface inspection apparatus 10. It is a figure explaining the repeating direction (X direction) of the repeating pattern. It is a figure explaining the repeating direction (X direction) of the repeating pattern 22 when setting the test substrate 20 to a desired direction. It is a figure explaining the state which set the angle which the repeat direction (X direction) and the direction (V direction) of the vibration surface of the illumination light L1 make to several different angle (phi), ((phi) + (DELTA)), ((phi) +2 (DELTA)). It is a figure explaining the state which set the angle which the repetition direction (X direction) and the direction (V direction) of the vibration surface of the illumination light L1 make to the optimal 45 degree | times. FIGS. 4 (a) amplitude E _X of the regular reflection light L2 in angular position of ', E _Y' is a diagram illustrating the amplitude E _L4 of the polarization component L4. It is a flowchart which shows the procedure of the defect inspection of this embodiment. Is a diagram illustrating the various iterations direction X ₁ to X ₃ formed on the surface of the test substrate 20

Explanation of symbols

10 surface inspection apparatus; 11 stage; 12 alignment system; 13 illumination system;
14 light receiving system; 15 image processing unit; 20 test substrate; 22 repetitive pattern;
31 light source; 32 wavelength selection filter; 33 light guide fiber;
34, 37 Polarizing filter; 35, 36 Concave reflector; 38 Condensing lens; 39 Image sensor

Claims (2)

Illuminating means for illuminating a repetitive pattern formed on the surface of the test substrate with linearly polarized light;
A setting means for sequentially setting an angle formed by the direction of the surface of the vibrating surface of the linearly polarized light and the repeating direction of the repeating pattern at a plurality of different angles based on the outer shape reference of the test substrate ;
Measuring means for taking out a polarization component orthogonal to the plane of vibration of the linearly polarized light from the specularly reflected light generated from the repetitive pattern in each state set to the angle sequentially and measuring the light intensity of the extracted polarization component When,
A surface inspection apparatus comprising: a detecting unit that detects a defect of the repetitive pattern using a maximum value among the light intensities measured in the respective states. Illuminating means for illuminating a repetitive pattern formed on the surface of the test substrate with linearly polarized light;
The angle formed by the repetition direction of the repeating pattern and direction in the surface plane of vibration of the linearly polarized light, based on the outer shape standards of the test substrate, and setting means for sequentially setting the plurality of different angles,
In each state set to the angle sequentially , out of the specularly reflected light generated from the repetitive pattern, a polarization component orthogonal to the vibration plane of the linearly polarized light is extracted, and the extracted polarization component is used for the test substrate. Processing means for capturing images;
A surface inspection apparatus comprising: a detection unit configured to detect a defect of the repetitive pattern using each pixel value of the brightest image among the images captured in each state.

Images