JP3020546B2 - Foreign matter inspection device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defect inspection method and an apparatus for detecting a defect in a circuit pattern of a reticle, a photomask, or the like (hereinafter referred to as a reticle, etc.). The present invention relates to a defect inspection method and apparatus suitable for easily separating a fine defect from a circuit pattern with a simple configuration and detecting the defect.

[Conventional technology]

In the process of exposing a reticle or the like used to manufacture LSI or printed circuit boards, the circuit pattern of the reticle or the like is inspected before printing and transferring it onto a wafer. However, since the foreign matter does not normally transfer the circuit pattern onto the wafer, there is a problem that the total number of LSI chips becomes defective. This problem has been
With the increase in integration of LSIs, they have become more prominent, and the existence of even smaller sub-micron-order foreign substances has become unacceptable.

In order to prevent the above transfer failure, foreign particle inspection before the exposure step is indispensable, and various foreign particle inspection techniques have been conventionally provided for the management of reticles and the like. A method of obliquely irradiating with a light source having good directivity such as the above and detecting scattered light generated from a foreign substance is advantageous and generally used in terms of inspection speed and sensitivity. However, in the above inspection method, since diffracted light is also generated from the edge of a circuit pattern such as a reticle,
A device for discriminating and detecting only a foreign substance from the diffracted light is required, and a technique for that purpose is disclosed.

The first is a foreign matter inspection apparatus characterized by a linearly polarized laser, means for irradiating the laser light obliquely at a specific incident angle, and an imaging optical system using a polarizing plate and a lens (for example, Japanese Patent Application Laid-Open No. -101390), when linearly polarized light is radiated, the diffracted light from the circuit pattern and the scattered light from the foreign matter utilize the fact that the polarization directions of the light are different, and only the foreign matter is made to shine and is detected.

Secondly, there is provided a means for irradiating the sample to be inspected with a laser beam from an oblique direction to scan the sample, and the laser beam provided above the sample to be inspected so that the irradiation point of the laser beam and the converging point surface are substantially coincident with each other. A first lens for condensing the scattered light, a light shielding plate provided on the Fourier transform surface of the first lens for shielding regular diffracted light from the circuit pattern of the sample to be inspected, and the light shielding plate obtained through the light shielding plate A second lens for performing inverse Fourier transform of scattered light from a foreign substance; a slit provided at an image forming point of the second lens for shielding scattered light from a point other than a laser light irradiation point on the sample to be inspected; (For example, Japanese Patent Application Laid-Open No. Sho 59-65428). This device pays attention to the fact that a circuit pattern is generally formed in the same direction or a combination of a few directions in a field of view, and a space in which diffracted light by the circuit pattern in this direction is set on a Fourier transform plane. By removing the light with a filter, only the scattered light from the foreign matter is to be emphasized and detected.

Third, focusing on the fact that the diffracted light generated at the edge of the circuit pattern has directivity, but the scattered light due to foreign matter does not have directivity, the logic of the detection output of each of the detectors installed at a plurality of locations is considered. The configuration is such that foreign matter is discriminated by taking the product (for example, Japanese Patent Application Laid-Open No. 59-186324).

Fourth, a plurality of detectors are used, utilizing the phenomenon that diffracted light from a circuit pattern edge concentrates only in a specific direction, while scattering from a foreign substance in all directions. It is arranged to discriminate foreign matter (for example,
JP-A-60-154634 and JP-A-60-154635).

Techniques related to the Schlieren method, a phase-contrast microscope, and a diffraction image of a light source having a finite size are known as methods and apparatuses related to the inspection of minute foreign substances. For example, Hiroshi Kubota,
Applied Optics (Iwanami Zensho), pp. 129-136.

[Problems to be solved by the invention]

In the prior art 1 (for example, Japanese Patent Application Laid-Open No. 54-101390), the difference between the polarization direction of the scattered light from the minute foreign matter and the polarization direction of the diffracted light from the edge of the circuit pattern is reduced. There was a problem that it could not be detected.

Next, the aforementioned prior art 2 (for example, Japanese Patent Laid-Open No. 59-6542).
No. 8) separates the scattered light from the foreign matter from the diffracted light from the circuit pattern by a light-shielding plate, and detects only the scattered light from the foreign matter by a slit.
It has a feature that the detection mechanism is simplified because it is detected by the binarization method, but the diffracted light from the intersection of the circuit pattern has a small tendency to be biased to a specific position like the diffracted light from the linear portion, and the space Diffracted light from the intersection of circuit patterns cannot be completely blocked by the filter, and diffracted light generated from circuit patterns having micron-order microstructure patterns due to the recent high integration of LSIs is due to foreign matter. Since the behavior is similar to that of the scattered light, it is much more likely that the above-mentioned tendency is strong, and it is practically difficult and problematic to detect the foreign matter separately from the circuit pattern by a simple binarization method.

Further, the above-mentioned prior art 3 (for example, Japanese Patent Application Laid-Open No. 59-1863)
No. 24) and the aforementioned prior art 4 (for example,
In each of the devices described in JP-A-60-154634 and JP-A-60-154635), it is difficult to employ an optical system having a sufficient light-collecting ability due to the configuration of the device, and the weakness generated from minute foreign matter is difficult. Detecting such scattered light has a practically difficult problem.

The present invention has been made in view of the above-described problems of the related art, and has a defect inspection method capable of easily detecting a submicron-order minute defect generated in a circuit pattern of a reticle or the like with a simple configuration and easily separating the circuit pattern from the circuit pattern. And an apparatus therefor.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a defect inspection device for inspecting a defect of a circuit pattern formed on a substrate,
Stage means capable of mounting and moving a substrate, a first light source unit for irradiating the substrate mounted on the stage means from an oblique direction, and irradiating the substrate from the oblique direction in opposition to the first light source unit An irradiating unit having a second light source unit for irradiating light, and a scattered light and a diffracted light generated from a circuit pattern on the substrate irradiated by the irradiating unit and condensed. Condensing / separating optical system means for separating the scattered light and the diffracted light from the second light source section and the second scattered light and the diffracted light, and the first condensing / separating optical system means And a second detector for detecting light based on the second scattered light and the diffracted light separated by the condensing / separating optical system means.
And a first binarized signal obtained by binarizing a signal detected by the first detection unit of the detection unit and a signal detected by the second detection unit. 2nd value obtained
And a defect judging means for judging a defect of a circuit pattern formed on the substrate from a logical product of the binarized signal and the binary signal.

In order to achieve the above object, according to the present invention, a defect inspection apparatus that detects a defect in a circuit pattern formed on a substrate includes: a first light irradiating unit that irradiates the substrate with light having a first wavelength; A second light irradiating means for irradiating the substrate with light of a second wavelength, and light of the first wavelength and light of the second wavelength are irradiated by the first light irradiating means and the second light irradiating means. An optical system for condensing the light from the substrate, and a second light condensed by the optical system and the first light from the substrate due to the light of the first wavelength condensed by the optical system. Separation means for separating the second light from the substrate by the light having the wavelength; first image detection means for detecting an image of the first light from the substrate separated by the separation means; Second image detecting means for detecting an image by the second light, and detecting the image by the first light by the first image detecting means. A first binarized signal obtained by binarizing the obtained signal and a second binarized signal obtained by binarizing a signal obtained by detecting an image formed by the second light with the second image detecting means. Defect detecting means for detecting a defect of a circuit pattern formed on the substrate from a logical product.

In order to achieve the above object, according to the present invention, in a defect inspection method for detecting a defect in a circuit pattern formed on a substrate, the first laser and the second laser are applied to the substrate placed on the stage. Irradiation is performed from the oblique direction, and scattered light and diffracted light generated from the circuit pattern on the substrate are condensed by the irradiation, and the collected scattered light and diffracted light are irradiated on the substrate by the first laser irradiation. The first scattered light and the diffracted light generated from the circuit pattern and the second scattered light and the diffracted light generated from the circuit pattern on the substrate by the irradiation of the second laser are separated from each other.
Out of the scattered light and the diffracted light from the linear portion of the circuit pattern is shielded and detected by the first detector, and the separated second scattered light and the diffracted light are diffracted from the linear portion of the circuit pattern. The light is blocked and detected by the second detector, and the first
Formed on a substrate from a logical product of a first binarized signal obtained by binarizing the output detected by the second detector and a second binarized signal obtained by binarizing the output detected by the second detector The defect of the circuit pattern is determined.

Further, in order to achieve the above object, in a defect inspection method for detecting a defect of a circuit pattern formed on a substrate,
A substrate mounted on a stage is irradiated with first illumination light and second illumination light having different wavelengths, and the light generated from the circuit pattern on the substrate by this irradiation is condensed. The first light generated from the circuit pattern on the substrate by the irradiation of the first illumination light is separated into the second light generated from the circuit pattern on the substrate by the irradiation of the second illumination light. Image of the circuit pattern based on the first light
, An image of a second pattern based on the separated second light is captured, a second image is obtained, a first binarized image obtained by binarizing the first image, and a second The defect of the circuit pattern formed on the substrate is detected from the logical product of the second image and the second binarized image obtained by binarizing the two images.

[Action]

The present invention focuses on the fact that a circuit pattern such as a reticle is composed of straight lines in three directions of vertical, horizontal and oblique directions and intersections of the straight lines. The circuit pattern has an incident angle i (i <90 °) from an oblique direction with a laser beam or the like having good directivity.
When illuminated, the Fourier-transformed image of the diffracted light from the linear portion of the circuit pattern is condensed into a thin linear shape at a specific position on the Fourier-transformed image plane, regardless of the position of the circuit pattern in the irradiation visual field. On the other hand, it is known that the scattered light from the foreign material is not deviated to a specific position on the Fourier transform image plane.
However, the change in the intensity of the diffracted light from the intersections and microstructures of the circuit pattern has not been clarified, and all possible intersections and microstructures of the circuit pattern performed by the present inventors have been described. By measuring the shape, even if the intersection and the microstructure of the circuit pattern of the same shape are illuminated by the light source with the same incident angle, the intensity of the diffracted light from the circuit pattern is remarkable depending on the direction in which the light source irradiates the circuit pattern It was revealed to change.

Based on the above measurement results, the circuit pattern of the substrate placed on the inspection stage unit is obliquely shifted by 180 ° by the first and second illumination systems having independent light sources symmetrically arranged. When irradiated at an incident angle i, the scattered light and the diffracted light generated at the same position of the circuit pattern by the irradiation are condensed by the detection optical system and separated by the irradiation direction, and are separated on each Fourier transform surface after separation. The diffracted light from the linear portion of the circuit pattern is shielded and removed by the arranged spatial filter, and an inverse Fourier transform image is created and imaged on each detector of the illumination series to be detected. The output of each detector is binarized by a first and second binarization circuit in the signal processing system in which a threshold value is set, and an AND circuit of the binarized output is obtained by an AND circuit. . By taking this logical product, the foreign matter of the submicron order on the circuit pattern is detected separately from the circuit pattern, and it is possible to detect only the foreign matter.

〔Example〕

The configuration of one embodiment of the present invention will be described below with reference to FIG. In the figure, reference numeral 1 denotes an inspection stage unit, and the inspection stage unit 1 fixes a reticle 6 having a pellicle 7 to a fixing unit 8.
Z stage 9 fixed to the upper surface and movable in the Z direction
And an X stage 10 for moving the reticle 6 in the X direction via the Z stage 9, a Y stage 11 for moving the reticle 6 in the Y direction, and each of the Z stage 9, the X stage 10, and the Y stage 11. A stage drive system 12 for driving,
A focus position detection control system 13 for detecting the position of the reticle 6 in the Z direction. Each stage is controlled so as to be always in focus with the required accuracy during the inspection of the reticle 6. .

The scanning speed of the X stage 10 and the Y stage 11 can be set arbitrarily.
Set a constant acceleration time of 0.2 seconds, a constant velocity movement of 4.0 seconds, and a constant deceleration time of 0.2 seconds, and a stop time of about 0.2 seconds in 1/2 cycle, a maximum speed of about 25 mm / sec, and a cycle of 105 mm amplitude If the reticle 6 is formed so as to move and the reticle 6 is moved in steps of 0.5 mm in steps in the Y direction in synchronization with the equal acceleration time and equal deceleration time of the X stage 10, once If you transfer 200 times within the inspection time of 100mm, it will take 100mm in about 960 seconds
It can be transported, and a 100 mm square area can be scanned in about 960 seconds.

Further, the control system 13 for detecting the focus position may use an air micrometer, may detect the position by a laser interferometer, or may detect the contrast by projecting a stripe pattern. The coordinates
X, Y, and Z are directions shown in the figure.

Reference numeral 2 denotes a first illumination system, and 3 denotes a second illumination system, which are independent of each other and have the same components, and are arranged symmetrically with a shift of 180 ° to irradiate the inspection visual field 15. I do. Reference numerals 21 and 31 denote laser light sources.
The wavelength λ ₁ of _one is, for example, 830 nm, and the wavelength λ ₂ of the laser light source 31 is, for example, 780 nm, which are different wavelengths that can be separated optically. However, other wavelengths may be used as long as they can be separated optically. Reference numerals 22 and 32 denote condensing lenses, which condense the light beams emitted from the laser light sources 21 and 31, respectively, and irradiate them on the circuit pattern of the reticle 6. In this case, the incident angle i of the two with respect to the circuit pattern is set to be larger than about 30 ° in order to avoid the objective lens 41 of the detection optical system 4 to be described later, and when the object is the reticle 6 on which the pellicle 7 is mounted, the pellicle Since it must be less than approximately 80 ° to avoid 7, approximately 30 ° <i <80 °.

A detailed configuration example of the first illumination system 2 and the second illumination system 3 will be described with reference to FIG. 2 and FIG. Second
The figure shows a configuration example of the first illumination system 2 (in this case, the second illumination system 2).
3 is omitted because it has the same configuration), and FIG. 3 shows that the light beam emitted from the laser
It is a perspective view showing the state where it was sectioned parallel to the -Y plane. In the figure, the same reference numerals as those in FIG. 1 indicate the same parts. Reference numeral 21 denotes a laser light source using a semiconductor laser. Reference numeral 221 denotes a collimator lens, 222 denotes a half-wave plate, 223 denotes a concave lens, 224 denotes a cylindrical lens, 225 denotes a collimator lens, and 226 denotes a condenser lens. The laser light source 21 has a rectangular light emitting point 211 of about 1 μm or less in the horizontal (X direction) × several μm to several tens μm in the vertical (Y direction), and the laser light emitted from the light emitting point 211 Due to the diffraction phenomenon at 211, the light is diffracted at a wide angle in the horizontal direction (X direction) to form an elliptical light beam 212 as shown in FIG. 3, and the laser light source 21 uses a semiconductor laser. , And a linearly polarized light having a magnetic field vector in the Y direction. Further, in order to narrow the laser beam to the inspection visual field 15, it is necessary to emit the laser beam to the collimator lens 221 at a wider angle than the laser light source 21. For this reason, a laser beam having a longitudinal direction in the Y 'direction shown in FIG. 2 is formed by the cylindrical lens 224, and a half-wave plate 222 is provided in the optical path to make the P-polarized laser beam
゜ Rotated to S-polarized light. The reason for using S-polarized light is that, for example, when the incident angle i is about 60 °, the reflectance on the glass substrate is about 5 times higher than that of P-polarized light (for example, by Hiroshi Kubota, Applied Optics (Iwanami Zensho)) From page 144)
It is possible to detect even smaller foreign matter.

Then, in order to increase the illuminance of the first illumination system 2, the numerical aperture (NA) of the condensing system is set to about 0.1 and the laser beam is narrowed down to about 10 μm.
30 μm, the entire area S of the inspection visual field 15 shown in FIG.
(About 500 μm).
However, in this embodiment, as a countermeasure, the cylindrical lens 224 is tilted around the X 'axis shown in FIG. 2 (FIG. 2 shows the tilted state). It is possible to focus on the entire area S of the field of view 15, and the detector of the signal processing system 5 described later is used.
When a one-dimensional solid-state imaging device is used for 51,551, even if the inspection area of the inspection field of view 15 is linear as in the detection 51,551, the linear inspection area is illuminated with high illuminance and uniform distribution. It becomes possible to do.

Further, if the cylindrical lens 224 is tilted about the Y ′ axis in addition to the X ′ axis shown in FIG. 2, even if the incident angle i is 60 ° and the irradiation is performed from any direction, the inspection field of view 15 can be obtained. , It is possible to perform linear illumination with high illuminance and uniform distribution over the entire area S.

Reference numeral 4 denotes a detection optical system. The detection optical system 4 includes an objective lens 41 facing the reticle 6 and a viewing zone lens (hereinafter referred to as a field lens) 4 provided near an image forming position of the objective lens 41.
3, a mirror 42 for wavelength separation of the light beam condensed by the field lens 43, a band-shaped light shielding portion provided at the position of the Fourier transform with respect to the inspection visual field 15 of the reticle 6, and a spatial filter 44, 444 having a transmission portion outside thereof. And imaging lens
The inspection field of view 15 on the reticle 6 is formed on the detectors 51 and 551 of the signal processing system 5 described later. The field lens 43 is
Is focused on the spatial filters 44 and 444.

Reference numeral 5 denotes a signal processing system, and the signal processing system 5 includes the detectors 51 and 5.
It comprises a first and second binarization circuits 52 and 552 for binarizing the outputs of the detectors 51 and 551, an AND circuit 53, a microcomputer 54, and a display means 55.

The detectors 51 and 551 are formed of, for example, a charge-transfer type one-dimensional solid-state imaging device, and detect signals from a circuit pattern on the reticle 6 while scanning the X stage 10. Is present, the input signal level and light intensity increase, so the detector 5
The output of 1,551 is also formed to be large. Note that if one-dimensional solid-state imaging devices are used for the detectors 51 and 551 as described above, there is an advantage that the detection field of view can be widened while maintaining the resolution, but the present invention is not limited to this.
A dimensional element or a single element can also be used.

The binarization circuits 52 and 552 have threshold values for binarization set in advance, and when an output value equal to or higher than the reflected light intensity output from the detectors 51 and 551 and corresponding to a foreign substance having a size to be detected is input. , And outputs a logic level “1”.

The AND circuit 53 takes in the signals from the binarization circuits 52 and 552 and outputs the logical product of the two signals. When the AND circuit 53 outputs the logical level “1”, the microcomputer 54 determines that “there is a foreign object”, and detects the position information of the X stage 10 and the Y stage 11 and the detectors 51 and 5 which are not single elements.
In the case of 51, the position information of the foreign substance calculated from the pixel position in the element and the detection output values of the detectors 51 and 551 are stored as foreign substance data, and the result is output to the display means 55.

Next, the operation of the inspection apparatus will be described with reference to FIGS. In the figure, the same reference numerals as those in FIG. 1 indicate the same parts. FIG. 4 is a view showing an inspection state of the reticle 6, FIG. 5 is a plan view for explaining an angle pattern of a circuit pattern, FIG. 6 is a view showing a distribution state of scattered light and diffracted light on a Fourier transform plane. 7A is a diagram showing a corner portion of the circuit pattern, and FIG. 7B is a diagram showing FIG. 7A.
FIG. 8 is an explanatory diagram showing the relationship between a detection output value from a scattered light from a foreign substance and a detection output value from a circuit pattern,
FIG. 9 is a diagram showing a circuit pattern having a fine structure pattern, and FIG. 10 is a diagram showing an output value level of a foreign object and a detection signal detected from a corner portion of the circuit pattern.

In FIG. 4, reference numeral 70 denotes a Z stage 9
Foreign matter on reticle 6 fixed on top, 81 is circuit pattern
Reference numeral 80 denotes a straight line portion, and reference numeral 82 denotes a corner portion of the circuit pattern.

First illumination system 2 or second illumination system 3 on reticle 6
Irradiates from the oblique direction and generates the scattered light.
When condensed at 41, the circuit pattern 80 on the reticle 6 shown in FIG. 5 and the projected image of the illumination system 2 or 3 on the reticle 6 surface
When the angle θ defined by the positional relationship with the angle 60 is 0 °, the diffracted light of the angle pattern (hereinafter referred to as 0 ° pattern) on the Fourier transform plane of the objective lens 41 as shown in FIG. Appears in a band. Here, the angle θ of the circuit pattern 80
Are limited to the angle patterns of 0 °, 45 °, and 90 °, and the diffracted lights (b) and (c) from the patterns of 45 ° and 90 ° as shown in FIG. Since it does not enter the 41 pupil, it does not affect detection. On the other hand, foreign matter 70
Since there is no directionality, the scattered light from is spread over the entire surface on the Fourier transform surface as shown in FIG. 6 (e). For this reason, spatial filters 44 and 444 having a band-shaped light shielding portion on the Fourier transform surface and a transmission portion outside thereof are arranged to shield the diffracted light (a) from the 0 ° pattern shown in FIG. This makes it possible to detect the foreign matter 70 by distinguishing it from the circuit pattern 80.

However, the corner 82 formed at the intersection of the circuit pattern 80 shown in FIG.
As shown in FIG. 7B, since the light is composed of corners 820 having a continuous angle, the diffracted light (d) from the corner 82 tends to spread on the Fourier transform plane.
6,444 cannot be completely shielded by 4,444 (d)
It becomes as shown in. For this reason, one detector 51 or 55
When diffracted light from a plurality of corners 82 enters 1, the output V of the detector 51 or 551 increases, and it becomes impossible to detect the foreign matter 70 by discrimination. FIG. 8 shows this state, in which the detected output values 822 from the plurality of corner portions 82 are higher than the detected output values 821 from the single corner portion 82, and a dotted line 90 shown in FIG. Indicates that the detection output value 701 from the foreign substance 70 cannot be separated and detected if the binarization is performed at the level of.

As a countermeasure against the problem described with reference to FIG. 8, the present invention is configured so that the inspection field 15 on the reticle 6 is imaged on the detectors 51 and 551 via the objective lens 41, the imaging lenses 45 and 445, etc. By selecting the dimensions of the detectors 51 and 551 and the imaging magnification, the detection field of view 15 on the reticle 6 surface is set to an arbitrary size (for example, 4 μm × 4 μm). The diffracted light from 82 is prevented from simultaneously entering the detectors 51 and 551. However, even if it is possible to detect foreign matter having the conventional dimensions, it is difficult to detect foreign matter on the order of submicrons.
Depending on the shape of 80, the detection of separation from some corners 82 is insufficient, and due to the high integration of the LSI, it is shown in FIG. 9 which is smaller than the dimension 83 of the normal structural portion of the circuit pattern 80. Diffracted light generated from a circuit pattern having a micron-order dimension 84 is more similar in behavior to scattered light from the foreign matter 70, and therefore, it is more desirable to detect the foreign matter 70 separately from the circuit pattern. It's getting harder.

The present invention has a countermeasure described below for a circuit pattern having a micron-order dimension 84 as shown in FIG. 9 so that foreign substances can be detected. FIG. 10 is an explanatory view, in which 701 and 702 are detection output values of scattered light from a minute foreign matter 70 on the order of submicrons, and 864,874,865,875,866,876,867,877 are 0 ゜, 45 ゜, 9
All corners 8 formed by each circuit pattern of 0 ゜
Detection output value of diffracted light from 2, 861,871,862.872,863,873
Indicates detection output values of diffracted light from a microstructured circuit pattern having a dimension 84 on the order of microns. Of these, 701,861,862,863,864,865,866,867 indicate the detection output value of the first illumination system 2 and 702,871,872,873,87
4,875,876,877 indicates a detection output value of the second illumination system 3, for example, 861 ← → 871 is a detection output value of each illumination system at the same position of the circuit pattern, 861 is a value of the first illumination system 2, 871 indicates a value obtained by the second illumination system 3. Further, as can be seen from the figure, the foreign matter 70 has a smaller variation in the scattered light detection output value depending on the irradiation direction than the circuit pattern. Note that a dotted line 91 in the figure indicates a threshold value of the detection output value.

From FIG. 10 above, it has been found that the output of diffracted light varies greatly depending on the direction of irradiation even with the same circuit pattern,
In addition, when the reticle 6 surface is irradiated from two oblique directions, which are 180 ° shifted from each other, the output value of the diffracted light on either side is in the submicron order as shown by the mark ◎ in the figure. It can be seen that the output value is always smaller than the output value from the foreign matter. For this reason, in the present invention, each of the output values from the same position on the reticle 6 surface is separately detected by the detectors 51 and 551, and the smaller detected output value indicated by the ◎ mark is adopted. And after binarization by the binarization circuits 52 and 552,
The logical product is obtained by the logical product circuit 53, so that only the foreign matter 70 of submicron order can be separated from the circuit pattern 80 and detected.

As shown in FIG. 10, a threshold 9 is applied to the binarization circuits 52 and 552.
When 1 is set, the values equal to or greater than the threshold value 91 are the detection output values 701 and 702 of the foreign substance 70 and the detection output values 861,863 and 8 of the circuit pattern.
However, the binarized output from these circuit patterns is output only from one of the binarization circuits 52 and 552, and is not output from the AND circuit 53. Can be detected separately from the circuit pattern. In addition to the positional information of the X stage 10 and the Y stage 11 at the time of detection, if the detectors 51 and 551 are not single elements, a foreign substance calculated from the pixel position in the element is used.
The position information of 70 and the detection output values of the detectors 51 and 551 are stored as foreign object data in a memory managed by the microcomputer 54, and the stored contents are subjected to arithmetic processing to obtain a CR.
It is displayed on display means 55 such as T.

In addition, as another configuration of the first illumination system 2 and the second illumination system 3, the optical axes of the first illumination system 2 and the second illumination system 3 are set around the optical axis 23 shown in FIG. 90 ° (the second illumination system 3 is omitted but rotated similarly)
At the same time, the detection optical system 4 may be rotated by 90 ° around the optical axis 47 of the detection optical system 4 shown in FIG. In the case of this configuration, for example, the incident angle i is 60
When the angle is set to ゜, the illuminance of the illumination system is reduced by about half and the aperture size of the laser beam becomes larger than that in the above-described embodiment, but it is not necessary to tilt the cylindrical lens 224, and the inspection field of view 1
Since the entire area S of 5 is at the same focal position, there is an effect that the entire inspection area is focused.

〔The invention's effect〕

Since the present invention is configured as described above,
It has a remarkable effect that a fine defect on the order of submicron generated in a circuit pattern such as a reticle can be easily separated and detected from the circuit pattern mainly with a simple optical configuration.

[Brief description of the drawings]

The drawings are explanatory views of one embodiment of the present invention. FIG. 1 is a diagram showing an overall schematic configuration, and FIG. 2 is a diagram showing a configuration example of an illumination system in FIG. 1 (in this case, a symmetric side). 3 is omitted because it is the same configuration), FIG. 3 is a perspective view showing a state in which a light beam emitted from the laser light source in FIG. 2 is cross-sectioned at an arbitrary Z position parallel to the XY plane, and FIG. FIG. 5 is a view showing a reticle inspection situation, FIG. 5 is a plan view for explaining an angle pattern of a circuit pattern, FIG. 6 is a view showing a distribution state of scattered light and diffracted light on a Fourier transform plane, and FIG. ) Shows a corner portion of the circuit pattern, and FIG. 7B shows FIG. 5A.
FIG. 8 is a detailed view of a portion "a" of FIG. 8, and FIG.
FIG. 9 is a diagram showing a circuit pattern having a fine structure pattern, and FIG. 10 is a diagram showing an output value level of a foreign object and a detection signal detected from a corner portion of the circuit pattern. DESCRIPTION OF SYMBOLS 1 ... Inspection stage part, 2 ... First illumination system, 3 ... Second illumination system, 4 ... Detection optical system, 5 ... Signal processing system, 6
…… reticle, 9 …… Z stage, 10 …… X stage,
11 ... Y stage, 21,31 ... Laser light source, 44,444 ...
Spatial filter, 51,551 detector, 52 first binary circuit, 552 second binary circuit, 53 logical product circuit, 7
0 ... foreign matter, 80 ... circuit pattern, 221 ... collimator lens, 222 ... 1/2 wavelength plate, 223 ... concave lens, 224 ... cylindrical lens, 225 ... collimator lens, 226 ...
…Condenser lens.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-62-70739 (JP, A) JP-A-1-224692 (JP, A) JP-A-1-153943 (JP, A) JP-A-2- 16438 (JP, A) JP-A-61-91547 (JP, A) JP-A-4-204144 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 21 / 84-21 / 90

Claims (11)

(57) [Claims] 1. A defect inspection apparatus for inspecting a defect of a circuit pattern formed on a substrate, comprising: a stage means on which the substrate is mounted and movable; and an oblique means for obliquely mounting the substrate on the stage means. Irradiating means having a first light source unit for irradiating the substrate from above and a second light source unit for irradiating the substrate from an oblique direction in opposition to the first light source unit; The first scattered light and the diffracted light generated by the irradiation of the first light source unit and the second scattered light and the diffracted light generated by the irradiation of the second light source unit are collected by collecting the scattered light and the diffracted light generated from the circuit pattern. Condensing / separating optical system means for separating scattered light and diffracted light; a first detecting unit for detecting light based on the first scattered light and diffracted light separated by the condensing / separating optical system means; The second scattering separated by the condensing / separating optical system means And a detecting means and a second detector for detecting the light based on the diffracted light, the first detecting means
Of a first binarized signal obtained by binarizing a signal detected by the detection unit and a second binarized signal obtained by binarizing the signal detected by the second detection unit And a defect determining means for determining a defect of a circuit pattern formed on the substrate. 2. The condensing / separating optical system means includes a first spatial filter on a Fourier transform surface on an optical path of the separated first scattered light and diffracted light, and a second scattered light and diffracted light. And a second spatial filter on a Fourier transform surface on the optical path of (c), wherein the first and second spatial filters respectively shield diffracted light from a linear portion of the circuit pattern. Described defect inspection apparatus. 3. The first light source unit and the second light source unit irradiate an S-polarized laser beam onto the substrate, and the first detection unit and the second detection unit The defect inspection apparatus according to claim 1, further comprising a one-dimensional solid-state imaging device. 4. A defect inspection apparatus for detecting a defect in a circuit pattern formed on a substrate, comprising: first light irradiating means for irradiating the substrate with light of a first wavelength; Second light irradiating means for irradiating light of a wavelength, and light of the first wavelength and light of the second wavelength are irradiated by the first light irradiating means and the second light irradiating means. Optical system means for condensing light from the substrate, and first light from the substrate by the light of the first wavelength condensed by the optical system means and condensed by the optical system means Separating means for separating the second light from the substrate by the light of the second wavelength, and first image detecting means for detecting an image of the first light from the substrate separated by the separating means And second image detecting means for detecting an image by the second light from the substrate;
A first binarized signal obtained by binarizing a signal obtained by detecting an image formed by the first light by the first image detecting means, and an image formed by the second light by the second image detecting means. Defect detection means for detecting a defect of a circuit pattern formed on the substrate from a logical product of a signal obtained by detecting the signal and a second binarized signal. Inspection equipment. 5. The defect inspection apparatus according to claim 4, wherein said first light irradiating means and said second light irradiating means respectively irradiate the substrate with laser in an oblique direction. 6. The optical system according to claim 4, wherein the optical system collects the scattered light of the first wavelength light and the second wavelength light applied to the substrate. Defect inspection equipment. 7. A defect inspection method for detecting a defect in a circuit pattern formed on a substrate, wherein a first laser and a second laser are respectively obliquely opposed to the substrate mounted on a stage. And scattered light and diffracted light generated from the circuit pattern on the substrate by the irradiation are collected, and the collected scattered light and diffracted light are irradiated with the first laser to form a circuit pattern on the substrate. From the circuit pattern on the substrate by the irradiation of the second laser, and the first scattered light and the diffracted light generated from the circuit pattern on the substrate by the irradiation of the second laser. Of the light and the diffracted light, the diffracted light from the linear portion of the circuit pattern is shielded and detected by a first detector, and the separated second
Out of the scattered light and the diffracted light from the linear portion of the circuit pattern is detected by a second detector, and the output detected by the first detector is binarized into a first binary signal. Determining a defect of a circuit pattern formed on the substrate from a logical product of the binarized signal and a second binarized signal obtained by binarizing an output detected by the second detector; Inspection methods. 8. The defect inspection method according to claim 7, wherein each of the first laser and the second laser for irradiating the substrate is S-polarized light. 9. A method of inspecting a pattern formed on the substrate by irradiating the substrate while moving the first laser and the second laser relatively to the substrate. The defect inspection method according to claim 7, wherein: 10. A defect inspection method for detecting a defect in a circuit pattern formed on a substrate, wherein the substrate mounted on a stage is irradiated with first illumination light and second illumination light having different wavelengths. Then, the light generated from the circuit pattern on the substrate by the irradiation is collected, and the collected light is combined with the first light generated from the circuit pattern on the substrate by the irradiation of the first irradiation light. The light is separated into second light generated from the circuit pattern on the substrate by irradiation of the second illumination light, and an image of the circuit pattern based on the separated first light is taken to form a first image. Obtaining a second image by capturing an image of the second pattern based on the separated second light; obtaining a second image by binarizing the first image; From the logical product of the second image and the second binarized image obtained by binarizing the second image, Defect inspection method and detecting a defect of a circuit pattern form. 11. The defect inspection method according to claim 10, wherein each of said first illumination light and said second illumination light is a laser.