JPH11352075A - Foreign matter inspection device and foreign matter inspection method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To improve detection sensitivity of a foreign substance inspection device while coping with various substrate patterns. SOLUTION: An optical system including a substrate stage 1 on which a wafer 8 having a substrate pattern 10 and a foreign substance 11 on its surface is installed, and a laser 2, including a detection lens 3, a spatial filter 4, a polarizing plate 5, and an ND filter 6, And detector 7
The fixed filter 4 having a line and space pattern is used as the spatial filter 4.
Two or more a and b are arranged so that each pattern is orthogonal. Further, two or more liquid crystal filters are arranged as spatial filters.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foreign matter inspection apparatus and a foreign matter inspection method for detecting minute foreign matter on a substrate with a pattern, and more particularly, to a foreign matter inspection method which is effective when applied to the detection of minute foreign matter on a substrate with a pattern. It is about technology.

[0002]

2. Description of the Related Art Japanese Patent Laid-Open Publication No. 1-11 / 1999 discloses a method for inspecting foreign substances adhering to a substrate such as a semiconductor wafer on which products such as semiconductor integrated circuit elements are formed.
A foreign substance inspection method described in Japanese Patent No. 7024 is known, and as a practically used foreign substance inspection apparatus, for example, a “patterned foreign substance inspection apparatus IS-2500” manufactured by Hitachi Electronics Engineering Co., Ltd. is known.

In the technology described in the above publication or the technology embodied in the above-described apparatus, a minute foreign matter on a patterned substrate is detected by the following method.

That is, when a substrate (wafer) on an inspection stage is irradiated with a laser beam, incident light is diffracted and scattered by a pattern and foreign matter due to the formation of the semiconductor integrated circuit device on the wafer. In this specification, the term diffraction refers to light scattered from the substrate surface due to a periodic pattern, while the term scattering refers to light scattered from foreign substances on the substrate surface.

[0005] The diffracted light and the scattered light pass through the objective lens, pass through the spatial filter and the polarizing plate, and enter the photodetector. The presence or absence of foreign matter on the substrate can be detected from the amount of light incident on the photodetector. That is, when a foreign substance is present on the substrate, the amount of scattered light increases, and the increase in the amount of scattered light can be detected by the photodetector to detect the presence of the foreign substance. However, incident light to the photodetector includes not only scattered light due to foreign matter but also diffracted light due to a pattern.
Unless the diffracted light is removed, the detection sensitivity of foreign substances cannot be increased. Therefore, a spatial filter and a polarizing plate are used to shield the diffracted light by this pattern. Hereinafter, as to the light shielding method using the spatial filter, the technology described in the above publication and the technology used in the apparatus will be described.

[0006] The diffracted light includes a DRAM (Dynamic Random A).
Diffraction light from a repetitive pattern such as a pattern of a memory cell portion representing a ccess memory) and diffracted light from a pattern that is not necessarily strong in repetition such as a pattern of a peripheral circuit portion are included. When these diffracted lights pass through the optical system and are projected on the Fourier transform surface, the diffracted lights from the repetitive pattern such as the memory cell section are projected at a wide pitch, and the diffracted light is not necessarily strong from the pattern such as the peripheral circuit section. Are projected at a narrow pitch. In such a pattern having repetitiveness (periodicity), the light is projected at a certain pitch on the Fourier transform plane. Therefore, if a filter (spatial filter) that blocks light in accordance with this pitch is arranged on the optical path, the pattern becomes It is possible to remove the diffracted light from the light. On the other hand, the foreign matter randomly adheres to the substrate except in special cases, so that the projection on the Fourier transform surface has a very fine pitch or continuous distribution. For this reason, although the scattered light by the foreign matter is partially shielded, a large number of light passes through the spatial filter and enters the photodetector.

In the above apparatus, a plurality of types of spatial filters are prepared in view of the variety of patterns on the substrate, and an appropriate spatial filter is selected from the plurality of types of spatial filters by driving a motor. . The selected spatial filter is applied to the Fourier transform plane to remove the diffracted light. Such a spatial filter is a fixed pattern drawn on a flat plate. Fourier transform images of various substrate patterns are obtained in advance by simulation, and are patterned into patterns corresponding to the Fourier transform images. Thus, by providing about 30 types of spatial filters corresponding to various substrate patterns, it is possible to correspond to many products (substrate patterns).

On the other hand, a variable spatial filter capable of arbitrarily changing the pattern is disclosed in, for example, Japanese Patent Application Laid-Open No. 1-13939.
The liquid crystal filter described in JP-A-43-43 is known.

[0009]

However, in order to quickly respond to recent diversification of semiconductor integrated circuit devices, small-lot production of other products, development of semiconductor integrated circuit devices according to customer specifications for specific applications, and the like. There is a need to provide a spatial filter that can flexibly cope with various substrate patterns. However, in the above-described fixed filter, the types of filter patterns are limited to 30 types, and it is difficult to correspond to all types of substrate patterns. On the other hand, in order to quickly respond to various substrate patterns, it is not preferable to have a large number of spatial filters because the cost increases. Further, it is not realistic to obtain a filter pattern optimal for a large number of substrate patterns one by one by simulation and manufacture a spatial filter based on this.

On the other hand, a liquid crystal filter capable of forming an arbitrary filter pattern is a powerful means capable of coping with diversification of substrate patterns, but has a problem that the liquid crystal filter has a low light-shielding rate and cannot completely shield light. .

An object of the present invention is to provide an inexpensive spatial filter capable of coping with various substrate patterns.

Another object of the present invention is to improve the light blocking ratio of a liquid crystal filter.

Still another object of the present invention is to cope with various substrate patterns and to improve the detection sensitivity of a foreign substance inspection device.

The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0015]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows.

(1) A foreign matter inspection apparatus according to the present invention includes a means for irradiating a substrate with laser light, a lens system for collecting diffracted light or scattered light of the laser light on the substrate surface, and a lens system for collecting the laser light. A light detecting means for detecting the diffracted light or scattered light, and a diffracted light which is disposed on an optical path between the lens system and the light detecting means and which is diffracted by the pattern formed on the substrate among the diffracted light or the scattered light. A foreign matter inspection device having a spatial filter that shields light, wherein a plurality of spatial filters are arranged on an optical path in an overlapping manner.

According to such a foreign matter inspection apparatus, by arranging a plurality of types of spatial filters on the optical path in an overlapping manner, the number of filter patterns corresponding to the combination of the spatial filters is increased. It is possible to cope with various substrate patterns.

It should be noted that the spatial filter can be a fixed filter composed of a line and space pattern formed with an arbitrary width and pitch. Thus, a foreign substance inspection device can be configured at low cost. That is, by combining existing spatial filters, it is possible to divert substrate patterns inexpensively by diverting existing devices and mechanisms.

One of the plurality of fixed filters has a line and space direction parallel to the first direction, and at least another one has a line and space direction in the first direction. They are arranged in parallel to the orthogonal second direction. That is, the plurality of spatial filters includes a set of spatial filters having at least line and space patterns orthogonal to each other.
Since a set of spatial filters having line-and-space patterns orthogonal to each other is included as described above, diffracted light from the substrate pattern can be more completely removed (shielded). Thereby, the detection sensitivity of the foreign substance inspection device can be improved.

(2) The foreign matter inspection apparatus according to the present invention comprises a means for irradiating the substrate with laser light, a lens system for collecting diffracted or scattered light of the laser light on the substrate surface, and a lens system for collecting the laser light. A light detecting means for detecting the diffracted light or scattered light, and a diffracted light which is disposed on an optical path between the lens system and the light detecting means and which is diffracted by the pattern formed on the substrate among the diffracted light or the scattered light. A foreign matter inspection device having a spatial filter that shields light, wherein the spatial filter is a liquid crystal filter in which an arbitrary pattern is formed by pixels formed of a dot matrix, and a plurality of liquid crystal filters are arranged on the optical path so as to overlap each other. Things.

According to such a foreign matter inspection apparatus, since the spatial filter is formed of a liquid crystal filter, it is possible to easily cope with various substrate patterns, and a plurality of liquid crystal filters are arranged on an optical path. Therefore, the light blocking ratio of the liquid crystal filter can be improved. That is, one pixel of the liquid crystal includes a light-shielding portion that is shielded by the liquid crystal or the like and a transmission portion around the light-shielding portion. Can not. This is a structural problem due to the electrode wiring for driving the liquid crystal and the like, and there is a limit to the light blocking ratio as long as one liquid crystal filter is used. Therefore, in the present invention, the diffracted light from the substrate pattern that cannot be completely removed by one liquid crystal filter is shielded by a plurality of liquid crystal filters to improve the light shielding ratio. Thereby, the light shielding ratio of the diffracted light can be improved, and the detection sensitivity of the foreign matter inspection device can be improved.

One liquid crystal filter and another liquid crystal filter are so arranged that light passing through a light transmitting region between pixels of one liquid crystal filter of a plurality of liquid crystal filters is blocked by pixels of another liquid crystal filter. Adjust the position relative to the filter.

(3) The foreign matter inspection apparatus according to the present invention is a combination of the above-described foreign matter inspection apparatuses (1) and (2), and the plurality of spatial filters arranged on the optical path are fixed filters. And a liquid crystal filter. Also in this case, the effects (1) and (2) described above can be obtained similarly.

(4) A foreign matter inspection method according to the present invention is a foreign matter inspection method using the foreign matter inspection device described in (2) or (3) above, wherein the foreign matter inspection method is provided on an optical path between a lens system and a liquid crystal filter. An optical area sensor is arranged, and a pattern of a liquid crystal filter similar to the pattern is generated based on a pattern of diffracted light or scattered light detected by the optical area sensor.

According to such a foreign matter inspection method, a pattern corresponding to a Fourier transform image is detected by the optical area sensor, and can be removed by the liquid crystal filter, so that diffracted light from the substrate pattern can be effectively removed. And a highly sensitive foreign matter inspection method can be achieved.

When there are a plurality of liquid crystal filters, the relative positions of the plurality of liquid crystal filters or the relative positions of the patterns displayed on the plurality of liquid crystal filters are set such that the amount of light detected by the light detecting means is minimized. To adjust. In this way, by adjusting the relative position of the liquid crystal filter, the transmission portion between the pixels of one liquid crystal filter can be overlapped with the light shielding portion of the other liquid crystal filter, and the light shielding rate of the diffracted light by the substrate pattern by the liquid crystal filter is improved. And a highly sensitive foreign matter inspection method can be realized. Further, the improvement of the light blocking ratio can be achieved not only by the mechanical relative position change of the liquid crystal filter but also by the relative position change of the pattern generated by the liquid crystal filter, that is, by the generation of the pattern whose position is relatively changed by electrical control. realizable. Thus, it is possible to generate an optimum pattern that does not require a delicate mechanical adjustment and can realize position control between liquid crystal filters only by electrical control.

[0027]

Embodiments of the present invention will be described below in detail with reference to the drawings. In all the drawings for describing the embodiments, the same members are denoted by the same reference numerals, and a repeated description thereof will be omitted.

(Embodiment 1) FIG. 1 is a conceptual diagram showing an example of a foreign matter inspection apparatus according to an embodiment of the present invention. FIG. 2 is a perspective view mainly showing an optical system of the foreign matter inspection apparatus.

The foreign substance inspection apparatus according to the first embodiment includes an optical system including a substrate stage 1 and a laser 2, a detection lens 3, a spatial filter 4, a polarizing plate 5, an ND (Neutral Density) filter 6, and a detector. Seven.

A wafer 8 is held on the substrate stage 1,
The surface is irradiated with laser light 9 from the laser 2. When the substrate stage 1 moves in the xy directions (two-dimensionally), the irradiation of the laser beam 9 to the wafer 8 is scanned.

As the laser 2, for example, a discharge tube laser such as a helium neon laser or an argon laser, or a solid-state laser such as a semiconductor laser can be used. There are no particular restrictions on wavelength, oscillation mode (single mode or multimode), and the like. However, it is desirable to use near-infrared light or visible light in view of the demand for the spectral sensitivity and thermal noise of the detector 7 or the spectral transmittance of the detection lens 3 and the like.
The lasers 2 may be installed at positions symmetrical about 180 degrees, or may be arranged on all sides with an angle difference of 90 degrees from each other.

The laser beam 9 is applied to the wafer 8 at a predetermined incident angle. The incident angle can be, for example, 45 degrees, but is not particularly limited. However, the optical axis of the laser light 9 and the detection lens 3 are arranged so that the mirror reflection light of the laser light 9 by the surface of the wafer 8 does not enter the detection lens 3.
Here, the incident angle is determined by the distance between the surface of the wafer 8 and the laser beam 9.
Angle with the optical axis.

A substrate pattern 10 is formed on the surface of the wafer 8, and a foreign matter 11 adheres in some cases. Wafer 8
Is irradiated with laser light 9, diffracted light 12 is generated by the substrate pattern 10, and scattered light 13 is generated by the foreign matter 11. The foreign matter inspection apparatus uses the diffracted light 12 and the scattered light 1
3, the diffracted light 12 which effectively detects the scattered light 13 to detect the presence of a foreign substance and acts as noise.
Is effectively removed by the spatial filter 4 and the polarizing plate 5 to improve the detection sensitivity of the scattered light 13.

The substrate pattern 10 is a pattern of a semiconductor integrated circuit device as a product, and has various periodicities based on the periodicity of the semiconductor integrated circuit device. DRAM (Dyna
In a memory array region of a memory device such as a mic random access memory, there is a high degree of periodicity. In this case, the pitch of the diffracted light 12 on the Fourier transform surface 14 is widened, while the pitch is as high as the peripheral circuit region of the semiconductor integrated circuit device. If there is no periodicity, the pitch of the diffracted light 12 on the Fourier transform surface 14 is formed narrow. Here, the wafer 8 is illustrated as an example of the substrate with a pattern, but the present invention is not limited to this, and a storage medium such as a liquid crystal substrate, a reticle, a magnetic disk, or an optical disk may be used.

Examples of the foreign matter 11 include dust floating in a process environment, foreign matter generated in a film forming process, an etching process, and the like. Adheres to For this reason, the scattered light 13 from the foreign material 11 is
4 and is distributed as a very fine pitch or continuous pattern.

By utilizing such a difference in pitch between the diffracted light 12 and the scattered light 13 on the Fourier transform surface 14, the diffracted light 12 is effectively shielded and the scattered light 13 is transmitted through a large amount to detect the foreign matter 11. Improve sensitivity. The Fourier transform surface 14 is an optical virtual surface formed on the exit side of the detection lens 3, and the detection lens 3
Then, the scattered light 13 is condensed and Fourier transform is performed. The detection lens 3 can be configured by combining a general convex lens or a concave lens.

The spatial filter 4 is used to effectively shield the diffracted light 12 having a certain pitch in the light amount pattern on the Fourier transform surface 14 as described above. In the present embodiment, two fixed filters 4a and 4b are used as the spatial filter 4. The fixed filters 4a and 4b
It is arranged so as to overlap on the optical axis.

The fixed filters 4a and 4b have a plurality of line and space patterns as shown in FIG. Each line-and-space pattern is a pattern obtained by simulation in accordance with a substrate pattern assumed in advance, and among a plurality of line-and-space patterns, the most suitable for the substrate pattern 10 of the wafer 8 to be inspected now. A line and space pattern is selected and used.

Further, as shown in FIG.
“a” selects an optimal pattern by a slide mechanism that slides in the x direction, and the fixed filter 4b selects an optimal pattern by a slide mechanism that slides in the y direction. Here, the x direction and the y direction are orthogonal, but they need not necessarily be orthogonal. Further, as exemplified in the fixed filter 4a in the x direction, a plurality of (three in FIG. 2) fixed filters 4a are prepared, and an arbitrary fixed filter 4a can be used. Fixed filter 4
a has a moving mechanism in the z-axis direction. Note that a plurality of fixed filters 4b may be similarly prepared for the fixed filter 4b, and a moving mechanism in the z-axis direction may be provided.

As described above, by using the fixed filters 4a and 4b superimposed on the optical axis, even if the fixed filter 4a alone cannot effectively block the diffracted light 12, another fixed filter can be used. The diffraction light 12 can be shielded by the filter 4b, and the detection sensitivity of the foreign matter 11 can be improved.
In addition, by combining with the fixed filter 4b, even a variety of substrate patterns 10 that cannot be dealt with only by the fixed filter 4a,
And a variety of substrate patterns 10
Can be responded quickly and easily. Further, such an addition of the fixed filter 4b does not require much cost, and can provide a foreign substance inspection device at a low price.

Further, as shown in FIG. 4, a line and space pattern 4a 'by the fixed filter 4a and a line and space pattern 4a by the fixed filter 4b
and b ′ are orthogonal to each other. By arranging the line-and-space patterns 4a 'and 4b' orthogonally, the diffracted light 12 can be more effectively shielded.

The polarizing plate 5 is used together with the spatial filter 4 to shield the diffracted light 12. This is because when the laser light 9 irradiated with P-polarized light or S-polarized light is diffracted by the substrate pattern 10 orthogonal to the optical axis,
While the polarized light or the S-polarized light is preserved, the scattered light 13 scattered by the foreign material 11 does not preserve the polarized light, so that the diffracted light 12 is shielded.

The light that has passed through the spatial filter 4 and the polarizing plate 5 in this manner is a light in which much of the diffracted light 12 is blocked and a large amount of scattered light 13 is contained. The light containing a large amount of the scattered light 13 is converted into an electric signal by the detector 7 even if the light is adjusted to an appropriate amount by passing through the ND filter 6.

Next, the processing of the information on the foreign substance 11, that is, the processing of the electric signal detected by the detector 7 will be described. As shown in FIG. 1, the foreign matter inspection apparatus according to the present embodiment further includes an information processing system 15, memories 16a and 16b, a difference circuit 17, a threshold comparison circuit 18, and an output unit 19.

The electrical signal detected by the detector 7 is appropriately processed into a signal that can be processed by a computer in the information processing system 15 and stored in the memory 16a. Memory 16b
, A signal of an adjacent chip processed in advance is stored, and a difference circuit 17 calculates a difference between a value in the memory 16a and a value in the memory 16b. This difference is compared with a predetermined threshold by the threshold comparing circuit 18, and when a signal higher than the threshold is detected, it is determined that the foreign substance 11 is present, and the result is output to the output unit 19. Such an operation is repeated by driving the substrate stage 1 over the entire surface of the wafer 8.

As described above, in the foreign matter inspection apparatus according to the present embodiment, the spatial filter 4 is divided into a plurality of fixed filters 4a and 4b.
Further, by arranging the line-and-space patterns 4a 'and 4b' of the fixed filters 4a and 4b orthogonal to each other, the diffracted light 12 can be effectively removed, and the detection sensitivity of the foreign matter 11 can be reduced. Can be improved.
Further, it becomes possible to cope with various substrate patterns 10, and it becomes possible to inspect foreign substances of various kinds of semiconductor devices quickly and at low cost.

(Embodiment 2) FIG. 5 is a conceptual diagram showing an example of a foreign matter inspection apparatus according to another embodiment of the present invention. The foreign matter inspection device according to the second embodiment is different from the foreign matter inspection device according to the first embodiment in the spatial filter part, and the other parts are the same. Therefore, only the differences will be described.

The foreign substance inspection apparatus according to the second embodiment is similar to the foreign substance inspection apparatus according to the first embodiment in that a spatial filter 20 is disposed on the optical axis between the detection lens 3 and the polarizing plate 5. , Spatial filter 20 is composed of liquid crystal filters 20a and 20b. FIG. 6A is a conceptual perspective view showing an example of the liquid crystal filters 20a and 20b used in the second embodiment. FIG. 6B is a plan view in which the pixels 21 of the liquid crystal filters 20a and 20b are enlarged by four pixels. Thus, the liquid crystal filters 20a, 20b
Is used to generate a monochrome display at an arbitrary pixel 21, that is, an arbitrary pattern, and
A spatial filter that can handle 0 can be formed.

FIG. 7 is a conceptual diagram illustrating a method for generating a filter pattern on the liquid crystal filters 20a and 20b according to the second embodiment. The diffracted light 12 (including the scattered light 13) emitted from the detection lens 3 forms a light intensity pattern based on the substrate pattern 10 on the optical system Fourier surface 14. This pattern is mainly the diffracted light 12 and includes the scattered light 13, but its component is small.

The intensity pattern of the light is detected by the diffracted light detector 22. The diffracted light detector 22 is disposed between the spatial filter 20 and the detection lens 3, as shown in FIG. Further, since it is desirable that the diffracted light detector 22 detects the pattern of the light intensity on the surface, the CCD
(Charge Coupled Device) or the like is preferable.

The signal of the diffracted light detector 22 is transmitted to the drawing signal processing unit 23 of the liquid crystal filters 20a and 20b.
The same pattern is drawn on the liquid crystal filters 20a and 20b by inverting the black and white. In this way, a filter pattern corresponding to the light pattern on the optical system Fourier plane 14 is generated, and the diffracted light 12 can be shielded. That is, it is possible to generate the most effective light-shielding pattern of the diffracted light 12 by generating a filter pattern optimum for the substrate pattern 10 irrespective of the substrate pattern 10.

However, in the pixels 21 of the liquid crystal filters 20a and 20b, as shown in FIG. 6B, not all of the pixels become black, and the light-shielding portion 21a and the transmission portion 21b are formed in one pixel. It exists in. Therefore, 1
It is not possible to completely block the diffracted light 12 with only one liquid crystal filter 20a.

Therefore, the foreign matter inspection apparatus of the second embodiment uses two liquid crystal filters 20a and 20b to improve the light shielding property of the diffracted light 12. That is, as shown in FIG. 8, the same filter pattern is drawn on the two liquid crystal filters 20a and 20b, and as shown in FIG. 9, the light shielding part 21a of the liquid crystal filter 20a and the light shielding part 2 of the liquid crystal filter 20b are drawn.
1a 'is formed so as to be shifted. Thus 2
The liquid crystal filters 20a and 20b are used and their pixels are shifted from each other so that the liquid crystal filters 20a and 20b
The light-shielding portion 21a 'of the liquid crystal filter 20b is arranged at the position of the transmission portion 21b which cannot be shielded by the light-shielding portion 21a of
2 can improve the light-shielding property.

In such a foreign matter inspection apparatus, what kind of substrate pattern 10 is used by the liquid crystal filters 20a and 20b.
It is possible to always form an optimal filter pattern even on the wafer 8 having the liquid crystal filter, improve the reduction of the light shielding property when a liquid crystal filter is used, effectively shield the diffracted light 12, Detection sensitivity can be improved.

The liquid crystal filters 20a and 20b can be shifted from each other by fixing one of the liquid crystal filters (for example, the liquid crystal filter 20a) and connecting the other liquid crystal filter (for example, the liquid crystal filter 20b) to a minute moving mechanism having a micrometer. Alternatively, a method of moving by a small actuator or the like using a piezoelectric element or the like can be exemplified. Further, a method may be used in which the drawing signal processing unit 23 independently draws a filter pattern to be drawn on the liquid crystal filter 20a and a filter pattern to be drawn on the liquid crystal filter 20b, and shifts the relative position.

As the liquid crystal filters 20a and 20b, a 12.1 inch XGA panel, a 17 inch SXGA
A panel or a 20-inch UXGA panel can be used. The size of the pixel 21 is such that the pixel pitch is 0.24 to 0.263 mm, and the width of the transmissive portion 21b is 15
To 25 μm.

(Embodiment 3) FIG. 10 is a conceptual diagram showing an example of a foreign matter inspection apparatus according to still another embodiment of the present invention. The foreign substance inspection apparatus according to the third embodiment is the same as the foreign substance inspection apparatus according to the second embodiment except that a fixed filter and a liquid crystal filter are used as spatial filters. Therefore, only the differences will be described.

The foreign substance inspection apparatus according to the third embodiment uses a fixed filter 24a and a liquid crystal filter 24b as the spatial filter 24. The fixed filter 24a
The liquid crystal filter 24b is the same as the liquid crystal filter 20a or 20b of the second embodiment, and is similar to the fixed filter 4a or 4b of the first embodiment.
The method for driving the liquid crystal filter 24b and the method for forming the filter pattern are the same as those described in the second embodiment.

In such a configuration of the spatial filter 24, the fixed filter 24a or the liquid crystal filter 24b
It is possible to effectively shield the diffracted light 12 that cannot be shielded only by itself, and improve the detection sensitivity of the foreign matter 11.

It goes without saying that a plurality of fixed filters 24a or a plurality of liquid crystal filters 24b may be provided.

Although the invention made by the inventor has been specifically described based on the embodiments of the present invention, the present invention is not limited to the above embodiments, and various modifications may be made without departing from the spirit of the invention. Needless to say, it can be changed.

For example, in the first embodiment, an example is shown in which two fixed filters are arranged, but three or more fixed filters may be arranged.

In the second or third embodiment, the method of directly drawing the light pattern detected by the diffracted light detector 22 has been described as a pattern forming method of the liquid crystal filters 20a, 20b, 24b. The corrected signal may be fed back to make appropriate correction to the filter pattern. Such a correction is
It can be provided as an additional function of the drawing signal processing unit 23.

[0064]

The effects obtained by typical ones of the inventions disclosed in the present application will be briefly described as follows.

(1) A spatial filter capable of coping with various substrate patterns can be provided at low cost.

(2) The light blocking ratio of the liquid crystal filter can be improved.

(3) It is possible to cope with various substrate patterns and to improve the detection sensitivity of the foreign substance inspection device.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing an example of a foreign matter inspection apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view mainly showing an optical system of the foreign matter inspection apparatus according to the first embodiment;

FIG. 3 is a plan view showing an example of a fixed filter according to the first embodiment.

FIG. 4 is a plan view showing an example in a case where the fixed filters according to the first embodiment are arranged in an overlapping manner.

FIG. 5 is a conceptual diagram showing an example of a foreign substance inspection device according to another embodiment of the present invention.

FIG. 6A is a perspective conceptual view illustrating an example of a liquid crystal filter used in Embodiment 2, and FIG. 6B is a plan view in which pixels of the liquid crystal filter are enlarged by four pixels.

FIG. 7 is a conceptual diagram illustrating a method of generating a filter pattern on a liquid crystal filter according to a second embodiment.

FIG. 8 is a conceptual perspective view showing an example in which a plurality of liquid crystal filters according to the second embodiment are arranged.

FIG. 9 is an enlarged top view showing a pixel portion when a plurality of liquid crystal filters of Embodiment 2 are arranged.

FIG. 10 is a conceptual diagram showing an example of a foreign matter inspection apparatus according to still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate stage 2 Laser 3 Detection lens 4 Spatial filter 4a, 4b Fixed filter 4a ', 4b' Line and space pattern 5 Polarizer 6 ND filter 7 Detector 8 Wafer 9 Laser light 10 Substrate pattern 11 Foreign matter 12 Diffracted light 13 Scattered light Reference Signs List 14 Fourier transform surface 15 Information processing system 16a, 16b memory 17 Difference circuit 18 Threshold comparison circuit 19 Output unit 20 Spatial filter 20a, 20b Liquid crystal filter 21 Pixel 21a, 21a 'Light shielding unit 21b Transmission unit 22 Diffracted light detector 23 Drawing signal processing unit 24 spatial filter 24a fixed filter 24b liquid crystal filter

 ──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Masami Ikoda 3-16-1, Shinmachi, Shinmachi, Ome-shi, Tokyo Inside the Device Development Center, Hitachi, Ltd. (72) Inventor Junichi Taguchi 3--16 Higashi, Shibuya-ku, Tokyo No. 3 Inside Hitachi Electronics Engineering Co., Ltd.

Claims (8)

[Claims] 1. A means for irradiating a substrate with laser light, a lens system for condensing diffracted or scattered light of the laser light on the substrate surface, and a diffracted or scattered light condensed by the lens system A light detecting means for detecting the light, and a diffracted light which is arranged on an optical path between the lens system and the light detecting means and which is diffracted by the pattern formed on the surface of the substrate out of the diffracted light or the scattered light. What is claimed is: 1. A foreign matter inspection device having a spatial filter that blocks light, wherein a plurality of the spatial filters are stacked and arranged on the optical path. 2. The foreign matter inspection device according to claim 1, wherein the spatial filter is a fixed filter composed of a line and space pattern formed with an arbitrary width and pitch. 3. The foreign matter inspection device according to claim 2, wherein one of the plurality of fixed filters is arranged so that a line and space direction thereof is parallel to the first direction, and at least another one of the plurality of fixed filters is arranged. Wherein the line and space direction is arranged parallel to a second direction orthogonal to the first direction. 4. A means for irradiating a substrate with laser light, a lens system for condensing diffracted or scattered light of the laser light on the surface of the substrate, and a diffracted or scattered light condensed by the lens system. A light detecting means for detecting the light, and a diffracted light which is arranged on an optical path between the lens system and the light detecting means and which is diffracted by the pattern formed on the surface of the substrate out of the diffracted light or the scattered light. A foreign matter inspection device having a spatial filter that blocks light, wherein the spatial filter is a liquid crystal filter in which an arbitrary pattern is formed by pixels formed of a dot matrix, and the liquid crystal filter is formed by stacking a plurality of liquid crystal filters on the optical path. A foreign matter inspection device characterized by being arranged. 5. The foreign matter inspection device according to claim 4, wherein the light passing through the light transmission region between the pixels of one of the plurality of liquid crystal filters is used as the pixel of another liquid crystal filter. A relative position between the one liquid crystal filter and another liquid crystal filter is adjusted so as to be shielded from light by the liquid crystal filter. 6. A means for irradiating a substrate with laser light, a lens system for condensing diffracted or scattered light of the laser light on the surface of the substrate, and a diffracted or scattered light condensed by the lens system. A light detecting means for detecting the light, and a diffracted light which is arranged on an optical path between the lens system and the light detecting means and which is diffracted by the pattern formed on the surface of the substrate out of the diffracted light or the scattered light. A foreign matter inspection device having a spatial filter that shields light, wherein the spatial filter is arranged in a plural number on the optical path, and the plurality of spatial filters have a line and space formed with an arbitrary width and pitch. A foreign matter inspection device, comprising: a fixed filter formed of a pattern; and a liquid crystal filter formed by a pixel formed of a dot matrix to form an arbitrary pattern. 7. A means for irradiating a substrate with laser light, a lens system for condensing diffracted or scattered light of the laser light on the substrate surface, and a diffracted or scattered light condensed by the lens system. And an arbitrary pattern formed by a pixel formed of a dot matrix, which is disposed on an optical path between the lens system and the light detection unit.
A foreign matter inspection method using a foreign matter inspection device having one or a plurality of liquid crystal filters, wherein an optical sensor is disposed on the optical path between the lens system and the liquid crystal filter, and the optical sensor is detected by the optical sensor. A foreign matter inspection method comprising: generating a pattern of a liquid crystal filter that approximates a pattern based on a pattern of diffracted light or scattered light. 8. The foreign matter inspection method according to claim 7, wherein when the number of the liquid crystal filters is a plurality, the number of the plurality of liquid crystal filters is set so that the amount of light detected by the light detection unit is minimized. A foreign matter inspection method, comprising adjusting a relative position or a relative position of a pattern displayed on the plurality of liquid crystal filters.