JP2001289794A - Defect inspection equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple defect inspection device, capable of inspecting defects based on diffracted light and scattered light from a substrate (object to be inspected) at high throughput. SOLUTION: This defect inspection device is provided with a means of illumination 13 for illuminating an object to be inspected 11, a means of separation 24 for separating diffracted light and scattered light from light from the object to be inspected 11, a first means of image pickup 27 for picking up the image of the object to be inspected based on the diffracted light, and a second means of image pickup 28 for picking up the image of the object to be inspected based on the scattered light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defect inspection apparatus for inspecting a defect on a substrate surface in a process of manufacturing a semiconductor circuit element or a liquid crystal display element.

[0002]

2. Description of the Related Art As is well known, in a process of manufacturing a semiconductor circuit element or a liquid crystal display element, a resist is formed through an exposure step of printing a circuit pattern on a photoresist film on a substrate and a development step of a photosensitive photoresist film. A circuit pattern is formed, and thereafter, a circuit is formed on the substrate by going through processing steps such as etching and vapor deposition.

In the manufacturing process, if there is a defect in a circuit pattern formed by a resist, processing is performed according to the defect, resulting in a defective product. Therefore, a defect inspection of a circuit pattern using a resist has been conventionally performed.
The defect location is, for example, a location where the cross-sectional shape of the circuit pattern has changed due to the defocus of the exposure device, a location where the thickness of the resist has changed, or a location where there is a foreign substance or a scratch.

At present, defect inspection in the actual manufacturing process is performed by visual observation. However, in the visual observation, a sufficient evaluation result cannot be obtained because the judgment standard changes depending on the skill and physical condition of the inspector. Therefore,
Automating this defect inspection is being considered. For example, Japanese Patent Application Laid-Open No. 11-51874 discloses an apparatus for automatically inspecting for defects based on an image based on diffracted light from a substrate and an image based on scattered light. Differences in brightness due to pattern abnormalities (defects) appear in images based on diffracted light, and differences in brightness due to foreign matter or scratches (defects) appear in images based on scattered light. The defect location can be specified by the brightness.

However, the intensity of the scattered light from the substrate is much lower than that of the diffracted light, and when receiving the scattered light and taking in an image, it is necessary to take measures to prevent the diffracted light from being mixed. For this reason, in the device disclosed in JP-A-11-51874, an illumination system optimal for receiving scattered light and an illumination system optimal for receiving diffracted light are separately arranged.

[0006]

However, in the above-described conventional apparatus in which a plurality of illumination systems are arranged, the illumination system must be switched between the time of receiving the scattered light and the time of receiving the diffracted light, so that the lighting system is illuminated. There is a problem that it takes time until the wavelength and the amount of light emitted from the light source are stabilized.
To solve this problem, a method is conceivable in which the illumination light source is always turned on and the illumination light is switched by a shutter disposed downstream of the illumination light source, but the apparatus becomes complicated.

Further, in the above-described method of switching the illumination system (or illumination light), the image capturing by receiving the scattered light and the image capturing by receiving the diffracted light are sequentially performed. There was a limit to speeding up. An object of the present invention is to provide a simple defect inspection apparatus capable of performing a defect inspection based on diffracted light and scattered light from a substrate (a test object) at a high throughput.

[0008]

According to the present invention, there is provided a defect inspection apparatus comprising: an illuminating means for illuminating a test object; a separating means for separating light from the test object into diffracted light and scattered light; A first image pickup unit for picking up an image of the test object based on the scattered light; and a second image pickup unit for picking up an image of the test object based on the scattered light.

The light generated from the test object illuminated by the illumination means contains a diffracted light component and a scattered light component. The diffracted light component and the scattered light component are separated by the separating means, and the diffracted light is guided to the first imaging means, and the scattered light is guided to the second imaging means. Therefore, a test object image based on diffracted light and a test object image based on scattered light can be simultaneously captured.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. (First Embodiment) The first embodiment of the present invention relates to Claims 1 and 2.
Claim 2 corresponds to claim 2, claim 4 and claim 5.

The defect inspection apparatus 10 according to the first embodiment has a structure shown in FIG.
As shown in FIG. 1, an inspection stage 12 on which a wafer 11 to be inspected is mounted, an illumination optical system 13 for illuminating the wafer 11 on the inspection stage 12, and a diffraction from the wafer 11 illuminated by the illumination optical system 13. A light receiving optical system 14 for receiving light and scattered light, a dark box 16 for housing the inspection stage 12, the illumination optical system 13, and the light receiving optical system 14, and a defect based on the image of the wafer 11 obtained by the light receiving optical system 14. And an image processing device 15 for detecting the presence / absence.

The inspection stage 12 holds the wafer 11 in a horizontal state. The normal direction of the wafer 11 is defined as the Z direction.
The surface 11a of the wafer 11 is parallel to the XY plane. The illumination optical system 13 (illumination means) is an eccentric optical system including a light source 21 and a concave reflecting mirror 22. Light source 21 (light source unit)
Is configured by, for example, a halogen lamp or a discharge light source, and emits white visible light (light flux L1) including a wide wavelength band. The emission surface of the light source 21 is arranged at a point that is approximately a focal distance of the concave reflecting mirror 22.

The concave reflecting mirror 22 is a reflecting mirror having an inner surface of a spherical surface as a reflecting surface, and is disposed obliquely above the inspection stage 12. That is, the axis (optical axis O1) passing through the center of the concave reflecting mirror 22 and the center of the inspection stage 12 is arranged so as to be inclined by a predetermined angle with respect to the Z direction.

Here, the direction parallel to the plane (incident plane) including the optical axis O1 and the normal line of the wafer 11 and orthogonal to the Z direction is defined as the Y direction. The plane of incidence is parallel to the YZ plane. A direction orthogonal to the Z direction and the Y direction is defined as an X direction. On the other hand, the light receiving optical system 14 includes a concave reflecting mirror 23 and a spatial filter 24.
, Imaging lenses 25 and 26, and CCD image sensors 27 and 2
8 is a decentered optical system.

The concave reflecting mirror 23 (condensing optical system) is a reflecting mirror similar to the concave reflecting mirror 22 described above.
2 above. That is, the axis (optical axis O2) passing through the center of the concave reflecting mirror 23 and the center of the inspection stage 12 is Z
It is arranged to be parallel to the direction. The optical axis O2 is
Included in the plane of incidence. The spatial filter 24 (separating means, optical member) is arranged to be inclined near the focal plane of the concave reflecting mirror 23. The position of the spatial filter 24 is near the pupil of the light receiving optical system 14 and is conjugate with the exit surface of the light source 21 described above.

As shown in FIG. 2, the spatial filter 24 includes a circular transparent plate 32 attached to an annular frame 31.
And a reflection film 33 formed on the surface of the transparent plate 32. The reflection film 33 has a rectangular shape elongated along the incident surface (YZ plane). The width D of the reflection film 33 in the direction perpendicular to the incident surface is slightly larger than the diameter of the image of the light source 21 (light source image) formed on the pupil plane of the light receiving optical system 14.

The portion of the transparent plate 32 of the spatial filter 24 where the reflection film 33 is formed is referred to as a "reflection portion 34"
A portion where 3 is not formed is referred to as a “transmission portion 35”. Incidentally, the spatial filter 24 is formed by forming a reflective film on the entire surface of the circular transparent plate 32 and then removing a part of the reflective film 33 by a technique such as etching to leave the reflective film 33 having the above-described shape. It can be manufactured by a method of depositing itself on the transparent plate 32. The transparent plate 32 is a transparent plate member such as a glass plate or a plastic plate. The reflection film 33 is made of, for example, gold,
It is composed of a metal film such as silver or aluminum or a dielectric multilayer film. In addition, in the transmission part 35 where the reflection film 33 is not formed,
It is preferable to apply an anti-reflection film.

The imaging lens 25 (FIG. 1) is disposed on the reflected light path of the spatial filter 24 (reflector 34).
The CD imaging device 27 is arranged so that its imaging surface substantially coincides with the focal plane of the imaging lens 25. Similarly, the imaging lens 26 is arranged on the transmission optical path of the spatial filter 24 (transmission unit 35), and the CCD imaging device 28 is arranged with its imaging surface substantially fixed to the focal plane of the imaging lens 26. . CC
The imaging surfaces of the D imaging elements 27 and 28 are the surface 1 of the wafer 11
Conjugate to 1a. The imaging lens 25 and the CCD imaging device 27 correspond to “first imaging means” in the claims, and the imaging lens 26 and the CCD imaging device 28 correspond to “second imaging means”.

The above-described inspection stage 12 and illumination optical system 1
3. The dark box 16 containing the light receiving optical system 14
This is a housing for preventing disturbance light from being mixed in when the image is taken. However, the dark box 16 contains the wafer 11
And a shutter that can be opened and closed (not shown). In the dark box 16, the wafer 11
Dust filter (eg, HE
It is desirable to circulate air in a laminar flow from an air purifier with PA or ULPA).

The image processing device 15 includes the CCD image pickup device 2
In addition to performing image processing on the images captured in steps 7 and 28, the light amount of the image is monitored, and a defective portion of the wafer 11 is specified based on the brightness of the image (described later). In the defect inspection apparatus 10 configured as described above, the white light flux L1 emitted from the light source 21 is reflected by the concave reflecting mirror 22 and then becomes a substantially parallel light flux (illumination light L2) on the inspection stage 12. Irradiation is performed on the wafer 11. The illumination light L2 is a light flux whose center line of the light flux reaching an arbitrary point on the wafer 1 is substantially parallel to the optical axis O1. The entire surface of the wafer 11 is illuminated at a predetermined angle (incident angle θi) by the illumination light L2.

Here, the orientation of the wafer 11 in the XY plane is determined based on the orientation flat and the notch by a positioning mechanism and a transport mechanism (not shown). It is mounted so as to be substantially orthogonal to the optical axis O1. For this reason, the illumination light L2 is incident on the repetitive pattern of the wafer 11 from the direction of 90 degrees. Then, from the repetitive pattern of the wafer 11, diffracted light L3 is generated in various directions within the incident plane (YZ plane).

Here, using the wavelength λ and the incident angle θi of the illumination light L2, the diffraction angle θk and the diffraction order k of the diffracted light L3, and the pitch p of the repetitive pattern,
It can be expressed by (1). p (sinθi−sinθk) = kλ (1) In equation (1), the incident angle θi is defined such that the angle direction seen on the incident side with respect to the normal line of the wafer 11 is plus, and the angle direction seen on the reflection side is minus. I do. With respect to the diffraction angle θk, the angle direction viewed on the incident side with respect to the normal line of the wafer 11 is defined as minus, and the angle direction viewed on the reflection side is defined as plus. The diffraction order k is defined such that the angle direction seen on the incident side is plus and the angle direction seen on the reflection side is minus with reference to the 0th-order diffracted light (specular reflection light) at k = 0.

Since the illuminating light L2 is white light including a wide wavelength band, the diffracted light L3 is generated in various directions of the diffraction angle θk satisfying the above equation (1) for each wavelength λ. However, any of the diffracted lights L3 is included in the incident plane (YZ plane). Further, when there is a foreign substance or a scratch on the surface 11a of the wafer 11, scattered light L4 is generated in addition to the diffracted light L3. Since the scattered light L4 is diffuse light, it travels not only in a direction parallel to the incident surface (YZ plane) but also in other directions (directions inclined with respect to the incident surface). In addition,
Since the illumination light L2 is white light, the amount of scattered light L4 is
The number is much larger than when monochromatic light is used.

The diffracted light L3 and the scattered light L4 generated from the wafer 11 as described above are reflected by the concave reflecting mirror 23, become convergent light, and reach the spatial filter 24 (pupil of the light receiving optical system 14). That is, the diffracted light L3 and the scattered light L4 are
The light is focused on the pupil of the light receiving optical system 14 by the concave reflecting mirror 23.

The diffracted light L3 is transmitted from the wafer 11 to the incident surface (Y
(Z plane), the spatial filter 24
The light reaches the reflecting portion 34 in FIG. 2 and is reflected there. on the other hand,
Since the scattered light L4 is generated in all directions from the wafer 11, most of the scattered light reaches the transmission portion 35 of the spatial filter 24 and is transmitted therethrough. As described above, the light generated from the wafer 11 is converted by the spatial filter 24 into the diffracted light L3 and the scattered light L4.
And separated.

Then, the diffracted light L3 reflected by the reflecting portion 34 of the spatial filter 24 is guided to the imaging lens 25 and the CCD image pickup device 27, and is imaged on the image pickup surface of the CCD image pickup device 27 by the image formation lens 25. You. Thereby, the wafer 1 by the diffracted light L3 is placed on the imaging surface of the CCD imaging device 27.
1 (diffraction image) is formed. On the other hand, spatial filter 2
The scattered light L4 transmitted through the transmission section 35 of the imaging lens 2
6. The image is guided to the CCD image pickup device 28 and is imaged on the image pickup surface of the CCD image pickup device 28 by the image forming lens 26. As a result, the scattered light L
4, an image (scattered image) of the wafer 11 is formed.

As described above, the two CCD image pickup devices 27,
Since the 28 is provided independently, a diffraction image and a scattered image of the wafer 11 can be taken at the same time. When the CCD image sensor 27 outputs an image signal based on the diffraction image of the wafer 11 to the image processing device 15, the image processing device 15 compares the diffraction image of the wafer 11 under inspection with the diffraction image of the non-defective wafer stored in advance. Pattern matching with the non-defective image) to determine whether there is a portion different from the feature of the diffraction image of the good wafer. If there is uneven brightness in the diffraction image,
A defective portion (for example, unevenness in film thickness or abnormal cross-sectional shape due to defocus exposure) is specified from the difference in brightness and characteristic of the portion.

When the CCD image pickup device 28 outputs an image signal based on the scattered image of the wafer 11 to the image processing device 15, the image processing device 15 compares the brightness value of the bright portion of the scattered image with a predetermined threshold value, Identify foreign objects and scratches on the top. Incidentally, the result of the inspection based on the diffraction image or the scattered image is processed integrally by a control computer (not shown), and the quality of the wafer 11 is determined. The pass / fail judgment of the wafer is sent to the process management system. The wafer judged to be good is proceeded to the next step, and the wafer judged to be bad is stripped of the resist pattern and reworked to perform the same process again, or the pattern is polished and recycled to start over from the first step. Is done.

As described above, according to the defect inspection apparatus 10 of the first embodiment, the light generated from the wafer 11 is separated into the diffracted light L3 and the scattered light L4 by the spatial filter 24, and the diffracted light L3 is Since the scattered light L4 is guided to the other CCD image pickup device 28, the diffraction image and the scattered image of the wafer 11 can be taken at the same time. Therefore, a pattern abnormality (defect) based on the diffraction image of the wafer 11
Inspection and inspection of foreign matter and scratches (defects) based on the scattered image of the wafer 11 can be automatically performed at high throughput.

Further, since the diffracted light L3 and the scattered light L4 can be separated only by the spatial filter 24 arranged on the optical path of the light generated from the wafer 11, a simple device can be realized. Further, the reflection part 34 of the spatial filter 24 is formed on the incident surface (YZ plane).
And the width D in the direction perpendicular to the incident surface is larger than the diameter of the light source image, so that all the various diffracted lights L3 generated from the wafer 11 can be guided toward the imaging lens 25 and the CCD image sensor 27. it can.

That is, all the diffracted light L3 is cut off by the reflecting portion 34 of the spatial filter 24 for the imaging lens 26 and the CCD image pickup device 28 for picking up the scattered light L4. Therefore, the diffracted light L3 is prevented from becoming stray light and being mixed into the scattered light L4, and a scattered image with a good SN can be captured. Therefore, it is possible to accurately inspect foreign substances and scratches (defects) based on the scattered image.

Further, since the white light is used as the illumination light L2, the amount of the scattered light L4 can be remarkably increased as compared with the case where monochromatic light is used. As a result, a scattered image with a good SN can be captured, and a defect inspection based on the scattered image can be accurately performed. On the other hand, regarding the defect inspection based on the diffraction image, the diffracted light L3 of various wavelengths λ and the diffraction order k generated from the wafer 11 by the white illumination light L2 can be guided to the imaging lens 25 and the CCD image sensor 27. ,
Even if the inspection stage 12 (wafer 11) is not tilted, defect inspection can be performed on a plurality of types of repetitive patterns having different pitches p at the same time.

For example, when patterns of different types (pitch p) are formed for each region of the wafer 11 like a circuit element of ASIC or Logic, white illumination light L2
Simultaneous inspection using is very effective. Further, by using the white illumination light L2, there is an advantage that a defect inspection based on a diffraction image can be performed with an appropriate sensitivity according to the wavelength width of the illumination light L2.

Since the scattered light L4 from the wafer 11 reaches not only the transmitting portion 35 of the spatial filter 24 but also the reflecting portion 34, the scattered light L4 reflected by the reflecting portion 34 is mixed into the diffracted light L3. I will. However, the intensity of the scattered light L4 is much lower than that of the diffracted light L3, so that the SN of the diffraction image does not decrease due to the influence of the scattered light L4. Further, in the defect inspection apparatus 10 of the first embodiment, since the inspection stage 12, the illumination optical system 13, and the light receiving optical system 14 are housed inside the dark box 16, it is possible to block disturbance light and diffract light from the wafer 11. Optical system 1 for efficiently receiving L3 and scattered light L4
4 can be led.

In the above-described embodiment, the spatial filter 24 that reflects the diffracted light L3 and transmits the scattered light L4 has been described as an example, but the spatial filter that separates the diffracted light L3 from the scattered light L4 is a diffracted light. A configuration that transmits the light L3 and reflects the scattered light L4 may be used. Further, the spatial filter 24 is not limited to the configuration in which the reflection film 33 is formed on the transparent plate 32, and may be a configuration in which a mirror made of glass, metal, or plastic is perforated.

Further, the example has been described in which the reflecting surfaces of the concave reflecting mirrors 22 and 23 are spherical. However, the reflecting surfaces may be aspherical such as a paraboloid or an ellipsoid. (Second Embodiment) A second embodiment of the present invention is described in claim 1
This corresponds to claims 3 to 5. As shown in FIG. 3, the defect inspection device 30 according to the second embodiment includes the concave reflecting mirrors 22, 23 of the defect inspection device 10 (FIG. 1) according to the first embodiment.
Are provided with refractive optical systems 42 and 43 in place of
A beam splitter 44 and two spatial filters 45 and 46 are provided in place of the zero spatial filter 24.
Other configurations are the same as those of the defect inspection apparatus 10. FIG.
, The same reference numerals are given to the same components as those in the apparatus of FIG. Here, a description will be given focusing on differences from the defect inspection apparatus 10 described above.

In the defect inspection apparatus 30, the refractive optical system 4
Reference numeral 2 denotes a lens that converts the white light beam L1 emitted from the light source 21 into a substantially parallel light beam (illumination light L2) and guides the light beam to the wafer 11 on the inspection stage 12. Also, the refractive optical system 4
Reference numeral 3 denotes diffracted light L3 and scattered light L4 generated from the wafer 11.
Is converted into convergent light and guided to the pupil of the light receiving optical system 34.

The beam splitter 44 (division member) divides the converging optical paths of the diffracted light L3 and the scattered light L4 generated from the wafer 11 into two, and is constituted by a half prism. The beam splitter 44 includes the light receiving optical system 3
The optical path splitting surface 44a is disposed between the pupil of the fourth optical system and the refractive optical system 43 with an inclination. One spatial filter 45 (optical member) includes a circular transparent plate 52 attached to an annular frame 51 and an absorbing film 53 formed on the surface of the transparent plate 52, as shown in FIG. . The part where the absorption film 53 is formed is called “absorption part 54”, and the part where the absorption film 53 is not formed is called “transmission part 55”. The transmitting portion 55 is provided on the incident surface (Y
(Z plane). The width D of the transmission part 55 in the direction orthogonal to the incident surface is slightly larger than the diameter of the light source image formed on the pupil plane of the light receiving optical system 54.

The other spatial filter 46 (optical member)
As shown in FIG. 5, it is composed of a circular transparent plate 62 attached to an annular frame 61 and an absorbing film 63 formed on the surface of the transparent plate 62. The part where the absorption film 63 is formed is called an “absorption part 64”, and the part where the absorption film 63 is not formed is called a “transmission part 65”. The absorbing section 64 has a rectangular shape elongated along the incident plane (YZ plane). The width D of the absorber 64 in a direction perpendicular to the plane of incidence is slightly larger than the diameter of the light source image formed on the pupil plane of the light receiving optical system 54.

The positions of these spatial filters 45 and 46 are as follows:
It is near the pupil of the light receiving optical system 34 and is almost conjugate with the exit surface of the light source 21. In the second embodiment, the beam splitter 44 and the two spatial filters 45 and 46 correspond to a “separating unit” in the claims. In the defect inspection apparatus 30 configured as described above, the diffracted light L3 from the wafer 11
The scattered light L4 is converted into convergent light via the refracting optical system 43, and is split by the beam splitter 44 in two directions.

The diffracted light L reflected by the beam splitter 44
3, the scattered light L4 reaches one of the spatial filters 45 and is transmitted through the beam splitter 44.
Reaches the other spatial filter 46. In one spatial filter 45 (FIG. 4), the diffracted light L3 is transmitted through the transmission part 55 and guided to the imaging lens 25 and the CCD image sensor 27, and the scattered light L4 is cut off by absorption in the absorption part. As a result, on the imaging surface of the CCD imaging device 27, the diffracted light L3
, An image (diffraction image) of the wafer 11 is formed.

Further, in the other spatial filter 46 (FIG. 5), the scattered light L4
6. The diffracted light L3 guided to the CCD image sensor 28 is blocked by the absorption in the absorbing section 64. As a result, the wafer 11 by the scattered light L4 is placed on the imaging surface of the CCD imaging device 28.
(Scattered image) is formed.

As described above, according to the defect inspection apparatus 30 of the second embodiment, the light generated from the wafer 11 is separated into the diffracted light L3 and the scattered light L4 by the beam splitter 44 and the spatial filters 45 and 46, and the diffracted light is diffracted. Light L3 is applied to one of C
Since the scattered light L4 is guided to the other CCD image pickup device 28 by the CD image pickup device 27, the diffraction image and the scattered image of the wafer 11 can be simultaneously taken.

Therefore, the inspection of the pattern abnormality (defect) based on the diffraction image of the wafer 11 and the inspection of the foreign matter and the flaw (defect) based on the scattered image of the wafer 11 can be automatically performed at a high throughput. Further, the diffracted light L3 and the scattered light L4 are generated only by the beam splitter 44 and the spatial filters 45 and 46 arranged on the optical path of the light generated from the wafer 11.
And a simple device can be realized.

Further, since the absorbing portion 64 of the spatial filter 46 is elongated along the incident plane (YZ plane) and the width D in the direction perpendicular to the incident plane is larger than the diameter of the light source image, various diffractions generated from the wafer 11 are performed. All of the light L3 can be absorbed. That is, all the diffracted light L3 is cut off by the absorbing portion 64 of the spatial filter 46 for the imaging lens 26 and the CCD image pickup device 28 for picking up the scattered light L4. Therefore, the diffracted light L3 is prevented from becoming stray light and being mixed into the scattered light L4, and a scattered image with a good SN can be captured. Therefore, it is possible to accurately inspect foreign substances and scratches (defects) based on the scattered image.

Since the transmitting portion 55 of the spatial filter 45 is elongated along the incident surface (YZ plane) and the width D in the direction orthogonal to the incident surface is larger than the diameter of the light source image, various diffractions generated from the wafer 11 are performed. All the light L3 is formed by the imaging lens 25 and CCD
It can be guided to the image sensor 27. Therefore, even if the inspection stage 12 (wafer 11) is not tilted, defect inspection can be performed on a plurality of types of repetitive patterns having different pitches p at the same time.

Since the scattered light L4 from the wafer 11 reaches the transmitting portion 55 of the spatial filter 45, the scattered light L4 transmitted through the transmitting portion 55 is mixed into the diffracted light L3.
Since the intensity of the scattered light L4 is much lower than the intensity of the diffracted light L3, the SN of the diffraction image does not decrease due to the influence of the scattered light L4. In the embodiment described above, the spatial filter 45 that transmits the diffracted light L3 and absorbs the scattered light L4, and the diffracted light L
Although the spatial filter 46 that absorbs the light 3 and transmits the scattered light L4 has been described as an example, the transmitting portions 55 and 65 may be configured by reflecting portions.

Although the example in which the transmitting portion 55 of the spatial filter 45 is elongated along the incident surface has been described, as shown in FIG. 6, the transmitting portion 55 may be a circular hole having substantially the same diameter as the light source image. it can. Even in this case, since white light is used as the light source, there is a wavelength λ that satisfies the conditions of the incident angle and the light receiving angle, and the inspection using diffracted light can be performed. In the defect inspection apparatus 30 of the second embodiment, the light from the wafer 11 is split in two directions by the beam splitter 44 in advance, and then the diffracted light and the scattered light are separated by the spatial filters 45 and 46. There is a drawback that the amount of light reaching the CCD image sensors 27 and 28 is smaller than in the case where the light beam is split by the spatial filter 24 and separated into diffracted light and scattered light as in the defect inspection apparatus 10 of the embodiment. , Each CC
There is an advantage that the spatial filters 45 and 46 for limiting the light flux reaching the D imaging elements 27 and 28 can be set independently.

In the above-described first and second embodiments, since the inspection using the diffracted light and the inspection using the scattered light can be performed simultaneously while the wafer 11 is mounted on one inspection stage 12, the stage is moved. There is no need to change or wait until each process is completed, and the time required for inspection of one wafer can be reduced. Furthermore, since there is only one stage, the entire defect inspection apparatus can be configured to be small. Therefore, the area occupied by the defect inspection apparatus is reduced in a factory having a high degree of cleanliness and requiring enormous costs for construction, and other apparatuses can be introduced accordingly. As a result, COO (CostOfOwn)
ership) can also be kept low.

Further, according to the defect inspection apparatus of the present invention, a human (which is a source of dust in a clean room) can inspect without approaching the wafer as compared with the conventional visual observation.
The possibility of extraneous adhesion of foreign matter is reduced, and the yield can be improved even when a dark box is not used. The present invention relates to a defect inspection apparatus 10 using a concave reflecting mirror for an illumination optical system and a light receiving optical system.
A configuration in which a beam splitter 44 and spatial filters 45 and 46 (FIG. 3) are provided instead of the spatial filter 24 (FIG. 1), and a defect inspection apparatus 30 (FIG. 1) using a refractive optical system for an illumination optical system and a light receiving optical system. The present invention can be applied to a configuration in which the spatial filter 24 (FIG. 1) is provided in place of the beam splitter 44 and the spatial filters 45 and 46 in 3).

Further, a device using a combination of a concave reflecting mirror (reflecting optical system) and a refracting optical system in the illumination optical system and the light receiving optical system may be combined with the spatial filter 24 (FIG. 1) or the beam splitter 44 and the spatial filter. 45, 46 (FIG. 3)
May be provided. The same effect can be obtained even when a light beam splitting surface similar to the spatial filter 24 described in the first embodiment is provided on the optical path splitting surface 44a of the beam splitter 44 of the second embodiment.

Incidentally, the CCD image pickup device 27 for picking up an image of the wafer 11 by the diffracted light L3 and the spatial filters 24, 45
By arranging a filter (combination with an interference filter or a color glass filter) that selectively transmits a light beam of a specific wavelength, a wafer image can be captured by diffracted light of a specific wavelength. The line width of a pattern formed on a semiconductor wafer is becoming thinner year by year, and the line width is 0.15 μm.
When m (that is, the pattern pitch is 0.3 μm) or less, diffracted light is not generated by the above-described visible light. In order to obtain diffracted light from a finer pattern, it is desirable to use electromagnetic waves such as ultraviolet light, X-rays, and γ-rays having a shorter wavelength than visible light.

It is conceivable to use synchrotron radiation for such a white light source having a shorter wavelength than visible light. Synchrotron radiation is radiation that is generated by rapidly deflecting accelerated electrons with a magnetic field or the like.
It has a wide wavelength band up to the line range. Synchrotron radiation can be extracted from one synchrotron in a plurality of directions.

Synchrotron radiation may be adopted as a light source for an exposure apparatus such as a wafer in the future.
In this case, one synchrotron can be used as both the light source of the exposure apparatus and the light source of the defect inspection apparatus of the present invention. Further, since light and electromagnetic waves having a shorter wavelength than visible light are absorbed by air, the inside of the dark box needs to be kept in a vacuum state or filled with a gas such as nitrogen which does not absorb short-wavelength light.

The defect inspection apparatus according to the present invention can also be applied to a defect inspection using an image based on specularly reflected light (zero-order diffracted light).

[0056]

As described above, according to the present invention, the wafer image (test object image) based on the diffracted light and the wafer image (test object image) based on the scattered light can be taken simultaneously. Multifaceted defect inspection using diffracted light and scattered light can be performed at high throughput, and as a result, manufacturing costs can be reduced. Further, it is possible to provide a simple defect inspection apparatus that does not require setting complicated inspection conditions.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a defect inspection apparatus 10 according to a first embodiment.

FIG. 2 is a diagram showing a pattern of a spatial filter 24.

FIG. 3 is a configuration diagram of a defect inspection device 30 according to a second embodiment.

FIG. 4 is a diagram showing a pattern of a spatial filter 45;

5 is a diagram showing a pattern of a spatial filter 46. FIG.

FIG. 6 is a diagram showing another pattern of the spatial filter 45.

[Explanation of symbols]

 10, 30 Defect inspection device 11 Wafer 12 Inspection stage 13, 33 Illumination optical system 14, 34 Light receiving optical system 15 Image processing device 16 Dark box 21 Light source 22, 23 Concave reflector 24, 45, 46 Spatial filter 25, 26 Imaging lens 27, 28 CCD imaging device 31, 51, 61 Ring frame 32, 52, 62 Transparent plate 33 Reflective film 34 Reflector 35, 55, 65 Transmitter 42, 43 Refractive optical system 44 Beam splitter 53, 63 Absorbing film 54, 64 Absorber

Continued on the front page F-term (reference) 2F065 AA49 BB01 CC19 DD06 FF04 FF41 FF48 GG02 GG03 GG24 HH03 HH12 JJ03 JJ05 JJ26 LL12 LL19 LL30 LL46 QQ39 RR08 2G001 AA01 AA02 AA07 BA13 BA01 CA02 LA11 MA05 SA02 2G051 AA51 AA90 AB07 AB20 BA05 CA04 CB01 CB05 CB06 CC07 CC15 CC20 EA12 4M106 AA01 BA04 CA38 DB03 DB04 DB07 DB12 DB19 DJ04 5B057 AA03 BA02 BA15 DA03

Claims (5)

[Claims] An illumination unit configured to illuminate an object to be inspected; a separation unit configured to separate light from the object into diffracted light and scattered light; and a first unit configured to capture an image of the object based on the diffracted light. A defect inspection apparatus, comprising: an image pickup unit; and a second image pickup unit for picking up an image of a test object based on the scattered light. 2. The defect inspection apparatus according to claim 1, wherein the separating unit includes an optical member disposed on an optical path of light from the object, and the optical member is provided from the object. And a portion that reflects or transmits a diffracted light component of the light and guides the diffracted light component to the first imaging unit, and a portion that transmits or reflects a scattered light component and guides the scattered light component to the second imaging unit. Defect inspection equipment. 3. The defect inspection apparatus according to claim 1, wherein the separating unit divides an optical path of light from the inspection object into at least two parts, and the two parts divided by the dividing member. An optical member disposed on each of the optical paths, wherein the optical member disposed on one of the two optical paths reflects or transmits a diffracted light component of light from the object to be inspected to thereby perform the first imaging. A part that guides the means, and a part that blocks the scattered light component, wherein the optical member disposed on the other of the two optical paths reflects or transmits the scattered light component of the light from the test object. A defect inspection apparatus comprising: a part that leads to the second imaging unit; and a part that blocks a diffracted light component. 4. The defect inspection apparatus according to claim 2, further comprising: a condensing optical system that condenses light from the test object, wherein the optical member includes a pupil of the condensing optical system. A defect inspection device, which is arranged in the vicinity. 5. The defect inspection apparatus according to claim 1, wherein the illuminating unit has a light source unit that emits white light, and illuminates the object with the white light. A defect inspection device characterized by lighting.