KR101275343B1 - Defect inspecting method - Google Patents

Abstract

assignment
Provided is a defect inspection apparatus capable of inspecting a pattern of an uppermost layer, especially a hole pattern, at a high S / N ratio.
Solution
From the wafer 2 illuminated by the illumination light L1, diffracted light L2 is generated, guided to the light receiving optical system 4, and condensed, and the image of the wafer 2 by the diffracted light L2 is obtained. It forms on the imaging element 5 as an imaging means. The image processing apparatus 6 image-processes the image received by the imaging element 5, and detects a defect. In the polarizing plate 7, the illumination light L1 illuminates the wafer 2 by S polarization, and the vibrating surface and the intersection of the wafer 2 are parallel or orthogonal to the wiring pattern formed on the wafer 2, and the polarizing plate (8) is adjusted to take out linearly polarized light of P polarization among the diffracted light from the wafer 2. By doing in this way, inspection of a hole pattern can be distinguished and inspected from the wiring pattern which exists under it, and the defect of a surface layer can be inspected in the state with favorable S / N ratio.

Description

How to check for defects {DEFECT INSPECTING METHOD}

TECHNICAL FIELD This invention relates to the defect inspection method which detects defects, such as a nonuniformity and a flaw of a board | substrate surface, for example in manufacturing processes of a semiconductor element.

Prior Art Literature Information

Japanese Laid-Open Patent Publication No. 11-51874

Prior art in the technical field to which the invention belongs

In the manufacture of a semiconductor device and a liquid crystal substrate, various different circuit patterns are formed, and the work of stacking them in layers is repeatedly performed. The outline of the step of forming each circuit pattern is applied by applying a resist to the surface of the substrate, baking the circuit pattern on the reticle or mask on the resist by an exposure apparatus, and developing the circuit pattern by the resist to form a circuit pattern, followed by etching. Each part of the element is formed. After the pattern by the resist is formed, it is checked whether or not the pattern is abnormal.

7 is a view showing an outline of a conventional inspection apparatus used for this purpose. Image of the substrate by diffracted light L2 generated from a repeating pattern (not shown) irradiated with illumination light L1 on the semiconductor wafer 2 mounted on the stage 3 and formed on the semiconductor wafer 2. Is taken in by the imaging element 5. And the image processing apparatus 6 performs image processing, and it detects the defect of the surface of a board | substrate by comparing with the image of a normal board | substrate. Since the direction in which the diffracted light exits from the semiconductor wafer 2 varies depending on the pitch of the repeating pattern, the stage 3 is appropriately tilted in accordance with this. As an example of such an apparatus, there is Unexamined-Japanese-Patent No. 11-51874.

Here, the object to be inspected is a resist pattern formed on the uppermost layer (topmost layer) of the semiconductor wafer 2, but a part of the light illuminating the substrate passes through the resist layer of the uppermost layer and illuminates the pattern formed on the ground. do. Therefore, the diffracted light generated from the entire substrate is affected by not only the resist pattern of the uppermost layer but also the underlying pattern. Therefore, when the influence of the underlying pattern is large, it becomes a noise, and there is a problem that the pattern information of the uppermost layer to be originally inspected is relatively small, and the S / N ratio worsens. In particular, hole patterns, such as contact holes, which combine circuit patterns of different layers, are fine, have a small pattern density, and have a low signal strength, and thus are susceptible to the influence of the ground, and conventionally, defects could not be sufficiently detected. .

In addition, when the anti-reflective film which absorbs the light used for inspection is formed between the uppermost pattern and the pattern below it, this problem disappears, but there existed a problem that it was difficult to obtain three-dimensional information of the pattern formed in the uppermost layer.

This invention is made | formed in view of such a situation, and makes it a subject to provide the defect inspection method which can perform the inspection of the pattern of a top layer by a high S / N ratio, and the inspection method of a hole pattern.

The 1st means for solving the said subject is a method of examining the surface defect of the board | substrate which is a to-be-tested object, The said board | substrate is illuminated with the illumination light of the linearly polarized light of P polarization, and the image of the said board | substrate by the diffracted light from the said board | substrate. And a defect of the substrate by detecting the captured image.

In this means, since the board | substrate is illuminated with the illumination light of the linearly polarized light of P-polarized light, it does not reflect on the surface of the pattern of a board | substrate surface, but enters inside of a board | substrate pattern, and there is much light reflected in the interface between board | substrate layers from there. Lose. Therefore, the change of the whole three-dimensional structure of the pattern of the board | substrate surface can be grasped | ascertained, and an inspection can be performed efficiently.

A 2nd means for solving the said subject is a method of inspecting the surface defect of the board | substrate which is a to-be-tested object, The said board | substrate by the linearly polarized light of P-polarized light which illuminates the said board | substrate with illumination light, and is contained in the diffracted light from the said board | substrate. And a defect of the substrate by detecting the image of the substrate and processing the captured image.

In this means, since the image of the substrate by linearly polarized light of P-polarized light included in the diffracted light from the substrate is picked up, similarly to the first means, the change in the overall three-dimensional structure of the pattern on the substrate surface is grasped. The inspection can be performed efficiently.

The 3rd means for solving the said subject is a hole pattern inspection method characterized by detecting the defect of the hole pattern formed in the surface of a board | substrate using either the said 1st means or the 2nd means.

Generally, hole patterns, such as a contact hole, are minute in size, and the reliable test | inspection was impossible with the conventional test method. According to this means, since the background noise can be reduced, the hole pattern can be inspected satisfactorily.

A fourth means for solving the above problem is a method for inspecting a defect in a hole pattern formed on a surface of a substrate under test, wherein the wiring pattern is formed on the substrate at a layer different from the hole pattern in which the vibrating surface of the substrate is different from the hole pattern. Illuminating with linearly polarized light of S-polarization parallel or perpendicular to the image, imaging the image of the substrate using the remaining light from which the linearly polarized light of S-polarized light included in the diffracted light from the substrate is removed, and processing the captured image It is a defect inspection method characterized by detecting the defect of the said board | substrate.

In the present specification and claims, the oscillation plane of linearly polarized light means a plane including an electric field vector of linearly polarized light and a traveling direction vector of light.

In this means, the board | substrate is illuminated with the illumination light of the linearly polarized light of S polarization, and also the intersection of the vibration surface and a board | substrate is made parallel or perpendicular to the wiring pattern formed in the board | substrate. And the image of the board | substrate is imaged using the remaining light from which the linearly polarized light of S polarization contained in the diffracted light from a board | substrate was removed.

In this case, since the vibration direction of the polarized light incident on the edge portion is perpendicular or parallel with respect to the wiring pattern, and the vibration component is only in the direction perpendicular to or parallel to the pattern, the vibration direction is affected by the influence from the pattern. Without causing a change, the direction of polarization itself does not change.

Therefore, the detected light decreases the reflected light from the top of the wiring pattern, and the reflected light from the abnormal part increases, so that the S / N ratio of defect detection can be improved.

As a method of removing the linearly polarized light of S-polarized light from diffracted light, there exists a method of arrange | positioning a polarizing plate so that the cross nicol condition is established between illumination light and diffracted light.

A fifth means for solving the above problem is a method for inspecting a defect in a hole pattern formed on a surface of a substrate to be inspected, wherein the wiring pattern is formed on the substrate at a layer different from the hole pattern in which the vibrating surface and the substrate are crossed. Illuminating with linearly polarized light of P-polarization parallel or perpendicular to the image, imaging the image of the substrate using the remaining light from which the linearly polarized light of P-polarized light included in the diffracted light from the substrate is removed, and processing the captured image The defect inspection method (claim 5) characterized by detecting the defect of the said board | substrate.

In this means, illuminating the substrate with illumination light of P-polarized linearly polarized light differs from the fourth means, and the principle thereof is the same as that of the fourth means. Therefore, similarly to the fourth means, the detected light can be suppressed from the shape of the wiring pattern, and a signal relating to only the shape of the hole pattern can be extracted to improve the S / N ratio of defect detection.

As described above, according to the present invention, it is possible to provide a defect inspection apparatus, a defect inspection method, and a hole pattern inspection method capable of inspecting the pattern of the uppermost layer at a high S / N ratio.

BRIEF DESCRIPTION OF THE DRAWINGS The figure which shows the outline | summary of the defect inspection apparatus which is a 1st example of embodiment of this invention.
Fig. 2 is a diagram showing the reflection states of P-polarized light and S-polarized light from the substrate surface and the base.
3 is a diagram showing an outline of a defect inspection apparatus according to a second embodiment of the present invention.
4 is a diagram illustrating an example of a hole pattern.
5 is a diagram schematically showing an example in which a hole pattern is respectively picked up by a defect inspection apparatus according to the present invention and a conventional defect inspection layer.
6 is a diagram illustrating an outline of a defect inspection apparatus according to a third embodiment of the present invention.
7 shows an outline of a conventional inspection apparatus.

EMBODIMENT OF THE INVENTION Hereinafter, the example of embodiment of this invention is described using drawing. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the outline | summary of the defect inspection apparatus which is a 1st example of embodiment of this invention. The illumination light L1 emitted from the lamp house LS is converted into almost parallel light by the lens 11 constituting the illumination optical system 1 to illuminate the wafer 2 mounted on the stage 3. do. A light source such as a halogen lamp or a metal halide lamp (not shown) and a wavelength selection filter are incorporated inside the lamp house LS, and only light having a portion wavelength is used as the illumination light L1.

The polarizing plate 7 is arrange | positioned in the vicinity of the exit part of the lamp house LS, and the illumination light L1 emitted from the lamp house LS is made into linearly polarized light. The polarizing plate 7 is rotatable with the optical axis of the illumination optical system 1 as the rotation center, and can arbitrarily change the polarization direction of linearly polarized light illuminating the wafer 2. In addition, insertion and extraction are possible by a mechanism (not shown). The stage 3 is provided with the tilt mechanism which is not shown in figure, and the stage 3 is tilted centering on the axis AX perpendicular | vertical to the surface.

Diffracted light L2 is generated from the wafer 2 which is a substrate illuminated by the illumination light L1. The diffraction angle of the diffracted light L2 changes with the pitch of the repeating pattern and the wavelength of the illumination light L1. The diffracted light L2 generated by properly tilting the stage 3 according to the diffraction angle is guided and collected by the light receiving optical system 4 composed of the lens 41 and the lens 42, and the wafer is subjected to the diffracted light L2. The image of (2) is imaged on the imaging device 5 as the imaging means of the present invention. Instead of tilting the stage 3, the whole from the lamp house LS to the illumination optical system 1 or the whole from the light receiving optical system 4 to the imaging device 5 is rotated about the axis AX. You may make it and may combine these, and may respectively tilt appropriately.

The image processing apparatus 6 image-processes the image received by the imaging element 5. If there is an abnormality such as the defocus of the exposure apparatus or the film thickness nonuniformity of the formed pattern, a difference in brightness occurs in the obtained image from the difference in diffraction efficiency of the normal portion and the defective portion. This is detected as a defect in the image processing. The abnormality may be detected by storing an image of a normal pattern in the image processing apparatus 6 and taking a difference between this and the measured pattern.

The diffraction light L2 is composed of a diffraction pattern of a resist pattern (upper layer pattern) on the surface of the wafer 2, and a mixture of the diffracted light at the underlying pattern (lower layer pattern) through the resist pattern on the surface. do.

Here, the polarizing plate 7 illuminates the wafer 2 with the S-polarized illumination light L1, and the intersection of the vibrating surface of the S-polarized light and the surface of the wafer 2 is parallel or perpendicular to the wiring pattern formed on the wafer 2. Rotation is adjusted around the optical axis as much as possible. The S polarization plane here is linearly polarized light in which the vibration plane is perpendicular to the surface of the paper. In addition, P polarization plane is a linear light beam whose vibration surface is parallel to the ground. In general, the reflectance of light on the surface of the thin film when light reaches the thin film from air differs in the P polarized light and the S polarized light depending on the refractive index and the incident angle of the thin film. In the range of 0 ° <incidence angle <90 °, the S polarized light has a higher surface reflectance.

When considering it as a wafer in which a plurality of pattern layers exist, the amount of light reaching the base becomes smaller as the S-polarized light has a higher surface reflectance. Therefore, the amount of diffracted light is also affected, and when the amount of light diffracted in the upper resist pattern is compared with the amount of light diffracted in the underlying pattern, the amount of light diffracted by the upper polar resist pattern is increased.

This state is demonstrated using FIG. 2 shows a state in which non-polarized light, S-polarized light, and P-polarized light are incident and reflected on a surface composed of a surface layer and a base, respectively. The amount of light reflected by the surface layer in the case of unpolarized a, the amount of light reflected from the interface between the surface layer and not b, the amount of light reflected by the surface layer in the case of S polarization a _s, the amount of light reflected from the interface between the surface layer and not b _In the case of _s , P polarized light, if the amount of light reflected by the surface layer is a _p , and the amount of light reflected by the surface layer and the underlying interface is b _p ,

a _p <a <a _s

b _p >b> b _s

. Therefore, by using S-polarized light, the amount of light reflected on the surface of the surface layer can be made relatively large, and the surface can be inspected without being influenced by the underlying.

Moreover, even if the polarizing plate 7 is inserted in a light receiving optical system instead of an illumination optical system, and the component of S polarization is taken out from the received diffraction light, the same effect as when inserting a polarizing plate in an illumination optical system can be acquired.

On the other hand, when there is an antireflection film just under the surface layer, and there is little reflected light (diffraction light) from the ground, or when the surface just below the surface is covered with a metal film without a whole surface pattern, the P polarized light is incident than the S polarized light. Preferably, the polarizing plate 7 is rotationally adjusted around the optical axis so that the illumination light L1 illuminates the wafer 2 with P polarized light. P polarization here is linearly polarized light whose oscillation surface is parallel to the ground. Although the P-polarized light has a lower reflectance on the surface than S-polarized light, it is not a problem even when P-polarized light is incident because it is hardly affected by the underlying pattern. Rather, P polarization has an advantage that it is easy to grasp the change in the three-dimensional structure of the pattern of the surface layer so that the amount of light incident inside the surface layer is larger than S polarization.

In particular, the inspection of the cross-sectional shape of a hole pattern has conventionally been the only means of fracture inspection which cuts a board | substrate and observes the cross-sectional shape with a scanning electron microscope. Since the hole pattern has a small pattern density unlike the line-and-space pattern, the hole pattern is inspected based on a cross section of some of the hole patterns that match the cut surface of the substrate. Further, depending on the crystal axis of the wafer and the formation direction of the hole pattern, all of the cross sections of the plurality of hole patterns may not coincide with the cut section. As described above, the observation of the cross-sectional shape of the hole pattern required the skill of the inspector to cut the substrate, which was a difficult operation. According to the present invention, inspection of the hole pattern is performed by P-polarized light to grasp the change in the overall three-dimensional structure of the hole pattern, so that the three-dimensional inspection of the hole pattern can be performed non-destructively and easily.

Moreover, even if the polarizing plate 7 is inserted in a light receiving optical system rather than an illumination optical system, and the component of P polarization is taken out from the diffracted light received, the same effect as when a polarizing plate was inserted in an illumination optical system can be acquired.

It is a figure which shows the outline | summary of the defect inspection apparatus which is 2nd Embodiment of this invention. In the following drawings, the same code | symbol is attached | subjected to the component same as the component shown in previous drawing, and the description is abbreviate | omitted. 2nd Embodiment adds the polarizing plate 8 in the light reception optical system 4 of 1st Embodiment shown in FIG. The polarizing plate 8 is rotatable using the optical axis of the light receiving optical system 4 as the rotation center, and can carry out linearly polarized light of arbitrary polarization direction among the diffracted light L2 from the wafer 2. Moreover, insertion and extraction are possible by the mechanism which is not shown in figure.

According to the fact confirmed by the inventors, in the defect inspection apparatus which is this 2nd Embodiment, the illumination light L1 is made into linearly polarized light (it is preferable to set it as the polarization state with the high reflectance on the substrate surface as described above). The state which adjusted each polarizing plate 7 and 8 to illuminate (2) and to extract the linearly polarized light which oscillates in the direction orthogonal to illumination light L1 among the diffracted light L2 from the wafer 2, Inspection in the so-called cross nicol state is particularly effective for inspection of hole patterns.

That is, in the case where the illumination light L1 is P-polarized with respect to the wafer 2, the S polarization of the diffracted light L2 from the wafer 2 is detected, and the illumination light L1 is S-polarized with respect to the wafer 2. In the case of, it is preferable to detect P polarized light in the diffracted light L2 from the wafer 2.

Usually, in a cross nicol state, an image becomes a dark field, but the area | region in which the hole pattern was formed was imaged as an image. This can be explained as follows. When the linearly polarized light is incident, the polarization state changes when reflecting diffraction on the surface of the sample to become an elliptically polarized light (components oscillating in the direction orthogonal to the vibration direction of the incident linearly polarized light appear). Therefore, by making it into a cross nicol state, only the component whose polarization state changed before and after sample incidence can be taken out.

In detail, the polarized light incident on the wiring pattern is usually decomposed into two components, a direction parallel to the linear direction (edge portion) of the wiring pattern and a direction (repetitive direction) orthogonal to the linear direction of the wiring pattern. Since the influences of the reflectance and phase shift amount due to the shape of the wiring pattern such as pitch and duty ratio are different from components parallel to the parallel component, the polarization after reflecting the wiring pattern, that is, the wiring pattern after reflection The polarization which synthesize | combined the component orthogonal to a parallel component changes shape with respect to the incident polarization. Therefore, when the relative position of the substrate and the illumination optical system is adjusted so that the intersection of the vibrating surface of the polarization incident on the edge portion and the wafer surface is perpendicular or parallel with respect to the wiring pattern of the layer different from the hole pattern, the vibration of the polarization of the light diffracted by the pattern is adjusted. The direction hardly changes. In this case, since the vibration direction of the polarized light incident on the edge portion with respect to the wiring pattern is vertical or parallel, the vibration component is only in a direction orthogonal to or parallel to the straight line direction of the wiring pattern. Since no change is caused in the vibration direction, the polarization direction itself does not change. On the other hand, since the hole pattern is a circular pattern, the relationship between the direction of vibration of the incident linearly polarized light and the direction of the edge portion is different depending on the position of the edge of the hole pattern (the vibration plane is perpendicular or parallel to the direction of the edge). Incident at an oblique angle). Therefore, among the light diffracted in the hole pattern, the signal component from the part of the hole pattern can be taken out without being reduced, and separation from the wiring pattern existing under the hole pattern becomes possible.

In the combination of cross nicol, S polarized light is incident as illumination light to extract the linearly polarized light component of P-polarized light out of the diffracted light from the wafer, and S polarized light component of the diffracted light from the wafer is extracted by entering P-polarized light as illumination light. There is a case. The former is suitable if the effect from the lower limb is to be as small as possible, and the latter is appropriate if the effective change of the entire three-dimensional structure of the hole pattern is to be understood. In each case, the polarizers (7, 8) This is adjusted appropriately.

Also in this case, since the influence of the base can be reduced, inspection of the hole pattern is performed by P-polarized light to grasp changes in the entire three-dimensional structure of the hole pattern, thereby non-destructively and easily three-dimensional inspection of the hole pattern. I can do it.

An example of a hole pattern is shown in FIG. (a) is a figure which shows the state of the contact hole 22 formed on the wiring pattern 21 as a lower layer, (b) is a figure of the contact hole 22 formed on the insulating layer 25 as a lower layer. It is a figure which shows the state. In both cases, the upper side is a plan view, and the lower side is an A-A sectional view. However, in order to make it easy to understand, in the top view in (a), the resist 23 is shown as transparent.

In (a), the wiring pattern 21 is formed on the board | substrate 24, and the contact hole 22 is formed in the predetermined hole pattern on it. A portion where the wiring pattern 21 is not formed is covered with a resist 23, and a portion where the contact hole 22 is not formed is covered with a resist 23 on the wiring pattern.

In (b), the wiring pattern 21 is formed on the board | substrate 24, the part in which the wiring pattern 21 is not formed, and the upper part of the wiring pattern 21 are covered with the insulating layer 25. As shown in FIG. Then, the contact hole 22 is formed through the insulating layer 25 in a predetermined pattern.

In the structure of (a), the wiring pattern 21 is formed just under the hole pattern 22. The pattern density of the wiring pattern 21 is larger than the pattern density of the hole pattern 22. In addition, the wiring pattern 21 is generally formed of a metal such as copper or aluminum having high light reflectance, whereas the resist layer 23 is formed of an organic compound such as polyhydroxystyrene that transmits light. . Therefore, the intensity of the diffracted light from the hole pattern 22 formed in the resist layer 23 becomes small compared with the intensity of the diffracted light transmitted through the resist layer 23 and diffracted in the wiring pattern 21, and the hole pattern 22. ) Is buried in the diffracted light diffracted in the wiring pattern 21.

For this reason, it was impossible to detect a signal of diffracted light from the hole pattern 22.

In addition, in (b), the wiring pattern 21 is formed on the board | substrate 24, and the insulating layer 25 is formed on it. The resist layer 23 is formed on the insulating layer 25, and the contact hole pattern 22 is formed on the resist layer 23 in a predetermined pattern arrangement. Since transparent SiO ₂ is generally used for the insulating layer 25, the light transmitted through the resist layer 23 is not absorbed by the insulating layer 25, and reaches the wiring pattern formed thereunder. Therefore, the light transmitted through the resist layer 23 and the insulating layer 25 reaches the wiring layer 21, and diffracted light from the wiring layer 21 is generated.

Also in this case, the intensity of the diffracted light diffracted in the hole pattern 22 formed in the resist layer 23 in the same manner as in (a) is compared with the intensity of the diffracted light transmitted through the resist layer 23 and diffracted in the wiring pattern 21. The signal of the diffracted light diffracted in the hole pattern 22 is buried in the signal of the diffracted light diffracted in the wiring pattern 21. Therefore, even when the wiring pattern 21 was formed through the insulating layer 25, it was impossible to detect the signal of the diffracted light from the hole pattern 22.

The inventor prepares a substrate having a structure as shown in (a), that is, a wafer in which a resist layer is formed directly on a wiring pattern having a defect-free repeating pattern made of aluminum (Al), and having the best focus and the best exposure dose. The hole pattern was exposed while changing focus amount and exposure amount centering on exposure conditions.

In the resist pattern after development, a hole pattern having a rectangular cross section is formed with the same diameter as the design value of the pattern exposed under the exposure conditions of the best focus and the best exposure amount. As the distance from the focus and exposure conditions increases, the diameter of the hole pattern While the deviation is caused from the design value, the rectangular shape of the pattern cross section is also reduced.

Various types of hole patterns on the wafer thus produced were imaged using the conventional inspection apparatus shown in FIG. 7.

A schematic diagram of the captured image is shown in FIG. 5 (b). Here, nine hole patterns with different exposure conditions are formed on one wafer, and the brightness of each imaging is shown. In the figure, the center hole pattern is exposed at the best focus and the best exposure amount, the pattern on the right shows that the focus is shifted in the optical axis direction plus, and the pattern on the left shows the focus is shifted in the optical axis direction minus. Moreover, the lower pattern shows that the exposure amount shifted to the positive side, and the upper pattern shows that the exposure amount shifted to the negative side.

As shown in the figure, in this state, due to the influence of the diffracted light from the underlying repeating pattern, the change in the hole pattern was not grasped as the brightness difference for each shot region. Therefore, the brightness of any of the hole patterns is similarly imaged.

The same wafer was measured using the inspection apparatus as shown in FIG. 3 in the state where cross nicol conditions hold with respect to the diffracted light from the base of a hole pattern. Fig. 5A is a schematic diagram of the captured image. Diffracted light from the underlying repeating pattern was removed, and a change in the focus amount and exposure amount of the exposure apparatus was identified as the brightness difference for each hole pattern region as shown in the figure.

The hole diameter changes depending on the change in the focus amount and the exposure amount, but this results in a difference in diffraction efficiency resulting in a difference in brightness of the image. The difference in brightness is sufficiently recognizable by image processing, and it is possible to discriminate defects in the hole pattern due to the defocus of the exposure apparatus or the trouble of the exposure amount.

It is a figure which shows the outline | summary of the defect inspection apparatus which is 3rd Embodiment of this invention. This embodiment differs from the second embodiment only in that the quarter wave plate 9 is disposed between the polarizing plate 8 and the wafer 2 in the light receiving optical system 4 of the second embodiment. The quarter wave plate 9 is rotatable with the optical axis of the light receiving optical system 4 as the rotation center. In addition, insertion and extraction are possible by a mechanism not shown. As is well known, the quarter wave plate has a function of converting the polarization state of light incident in the rotational direction into linearly polarized light, elliptically polarized light, and circularly polarized light.

As described above, the diffracted light L2 is a combination of diffracted light diffracted in the pattern of the upper layer and diffracted light diffracted in the pattern of the lower layer, and the polarization states are different. Thus, the quarter wave plate 9 is rotated and adjusted so that the diffracted light from the base becomes linearly polarized light, and the polarizer 8 is extracted so as to take out light that vibrates in a direction orthogonal to the vibration direction of the converted linearly polarized light. That is, the rotation is adjusted so as to be cross nicol. As a result, diffracted light from the base is removed. Here, although the polarization state changes after passing through the quarter wave plate 9, the diffracted light from the upper layer can pass through the polarizing plate 8 because it is not linearly polarized light. In this way, after the diffracted light L2 passes through the polarizing plate 8, since the diffracted light from the base is removed and only the diffracted light from the upper layer is received, the S / N is satisfactory without being affected by the underlying. The test can be performed in a state.

In addition, the quarter wave plate is inserted between the polarizing plate 7 and the wafer 2 of the illumination optical system 1 and the wafer 2 rather than the light receiving optical system 4, so that the quarter wave plate is properly diffracted by the wafer 2. The diffracted light from the base can also be linearly polarized light. Therefore, the same effect as when inserting a quarter plate into the light receiving optical system can be obtained.

1: illumination optical system 2: wafer
3: stage 4: light receiving optical system
5: Imaging Element 6: Image Processing Apparatus
7, 8: polarizer 9: 1/4 wavelength plate
21: wiring pattern 22: contact hole
23: resist 25: insulating layer
41, 42: Lens L1: Illumination light
L2: diffracted light

Claims (8)

A method for inspecting a defect in a pattern formed on a surface of a substrate under test,
Illuminating the substrate with linearly polarized light in which the vibrating surface and the intersection of the substrate are parallel or perpendicular to the extension direction of the pattern formed on the layer different from the pattern,
The defect inspection method characterized by imaging an image of the said board | substrate using the remaining light which removed the polarization component of the illumination light contained in the diffracted light from the said board | substrate, and processing the picked-up image, and detecting the defect of the said board | substrate. A method for inspecting a defect in a pattern formed on a surface of a substrate under test,
Illuminating the substrate with linearly polarized light of P-polarized or S-polarized light in which the vibrating surface and the intersection of the substrate are parallel or perpendicular to the direction of extension of the pattern formed on the layer different from the pattern,
And a defect of the substrate is detected by imaging an image of the substrate using the remaining light from which the polarization component of illumination light included in the diffracted light from the substrate is removed, and processing the captured image. 3. The method according to claim 1 or 2,
The pattern formed on the surface is a hole pattern, and the defect inspection method detects a defect of the hole pattern. 3. The method of claim 2,
Illuminating the substrate with linearly polarized light of P polarization,
And detecting a defect accompanying a three-dimensional structural change of the pattern formed on the surface of the substrate. An illumination part which illuminates the board | substrate which is a to-be-tested object which has a pattern on the surface by linearly polarized light,
A first polarizing part that transmits polarization components other than the direction of the linearly polarized light from light diffracted in the pattern;
An imaging unit which picks up an image of the surface by the transmitted polarization component;
It has an inspection part which detects a defect based on the said imaging result,
An intersection of the vibrating surface of the linearly polarized light and the substrate is parallel or perpendicular to an extension direction of a pattern formed in a layer different from the pattern on the surface. The method of claim 5, wherein
The said illumination part is equipped with the 2nd polarizing part in the optical path of illumination, The defect inspection apparatus characterized by the above-mentioned. The method according to claim 6,
At least one of the said 1st polarizing part and said 2nd polarizing part can rotate the optical axis of the optical path from the said illumination part to the said imaging part to a rotation center, The defect inspection apparatus characterized by the above-mentioned. 8. The method according to any one of claims 5 to 7,
And a tilting portion for tilting the substrate around an axis orthogonal to the incident surface of the illumination light.

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