JPS636854A - Foreign object inspection device - Google Patents

Abstract

PURPOSE:To enable detection of a foreign substance which scatters light so feebly that it cannot be discriminated from a pattern, by extracting a pattern edge portion from a transmitted light detection signal of a sample and discriminating light scattered by a foreign substance from said signal. CONSTITUTION:A pattern edge extracting circuit 23 processes a transmitted light detection signal and extracts a pattern edge on a photomask from said signal. A foreign substance dlscriminating circuit 24 removes a scattered light detection signal from the pattern edge from a detection signal supplied from a scattered light detection section 16 and determines whether any foreign substance is detected or not based on the data of said pattern edge. In this manner, minute foreign substances can be detected indenpendently from scattered light from the pattern edge. A flat-type foreign detection circuit 30 differentiates a detection signal given by illumination of transmitted light to emphasize the edge portions of a foreign substance if any and determines whether a foreign substance is detected or not.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention removes minute foreign particles on photomasks for semiconductor manufacturing at high speed.
The present invention relates to a foreign substance inspection device suitable for highly sensitive detection. [Prior art] A device for detecting foreign matter on a photomask is disclosed in Japanese Patent Application Laid-Open No. 59-6
No. 5428 and Japanese Unexamined Patent Publication No. 54-101390. Japanese Patent Application Laid-open No. 59-65428 discloses a foreign matter inspection device characterized by a linearly polarized laser, means for making the laser beam incident at a specific angle of incidence, and an imaging optical system using a polarizing plate and a lens. . In this device, when linearly polarized light is irradiated, the scattered light from the photomask substrate and the nozzle has a different polarization direction from the scattered light from the foreign object, so that only the foreign object is illuminated and detected. (This is explained in Proceedings of the Society of Instrument and Control Engineers, Vol. 17, Nn2, P23.
2-P242, 1981. It is stated in ) According to this method, the intensity of scattered light from Nositane is 2 to 3
It is sufficiently small compared to the scattered light from μm foreign matter, 2 to 3 μm.
It is possible to distinguish micrometer foreign objects from patterns and detect them. However, no consideration has been given to foreign particles whose scattered light intensity is as small as the pattern, 1 μm or less, and foreign particles which do not generate scattered light because they are flat. Further, the present invention refers to an image differentiation method. This method is described in a general reference book on image processing, for example, from pages 119 to 126 of Introduction to Computer Image Processing (Souken Publishing), edited by Japan Industrial Technology Center. Furthermore, Japanese Patent Laid-Open No. 101390/1983 discloses a laser light source. A means for irradiating the laser beam obliquely, a Fourier transform optical system using a lens, and a Fourier transform surface.

[A foreign object inspection device is disclosed that features an installed spatial filter and an imaging optical system. This device focuses on the fact that patterns generally consist of the same direction or a combination of two or three directions within the field of view, and uses a spatial filter installed on the Fourier transform surface to capture the diffracted light from the pattern in this direction. By removing the foreign matter, only the light reflected from the foreign object is emphasized and detected. Further, the Schlieren method is described in general optical reference books, for example, written by Hiroshi Kubota, Applied Optics (Iwanami Zensho), pages 129 to 136. Furthermore, as a related technology, a defect inspection method using a phase contrast microscope was proposed in a patent application filed in 1973.
9-186325, and pattern defect inspection apparatuses using reflected diffraction light are disclosed in JP-A-60-154634 and JP-A-60-154635. [Problems to be Solved by the Invention] In the conventional foreign object inspection apparatus, foreign objects and patterns are discriminated based on the intensity of scattered light by oblique illumination. This method has the problem that when it comes to minute foreign objects, the scattered light generated by oblique illumination is as weak as or even weaker than the pattern, making it impossible to distinguish it from the pattern. The problem is that foreign objects of the size of the object cannot be detected because no scattered light is generated by oblique illumination, regardless of the size of the foreign object. The following describes an experiment conducted to clarify this problem. Therefore, FIG. 6K shows the magnitude of scattered light detected in an experiment using the conventional technique for a photomask. FIG. 6 shows the magnitude of scattered light from the pattern edge with respect to the pattern angle. The pattern angle here is the angle defined by θ when the photomask is viewed from above, and in FIG. 6, the direction of the oblique illumination light is shown in FIG. 5, and the pattern is shown in FIG. 48. In Figure 6, φ
0.5μm standard particle, φ1.0μm standard particle, φ2.0
The magnitude of the scattered light detection signal from the μm standard particle vo,...
, Vlj) and V2J) are also shown. According to experiments, φ0.5. With standard particles having a diameter of 1.0 μm, the generation of scattered light is weak, so it is impossible to distinguish between foreign matter and patterns based on the intensity of the scattered light. Therefore, in the conventional technology,
It has been found that foreign matter of about 2 μm is the limit that can be stably detected. - On the other hand, the required performance for detecting foreign matter on a photomask is L
With the miniaturization of SI processing technology, it is required to detect even minuter foreign objects year by year. Among photomasks, especially in the case of a reticle, as shown in FIG.
is repeatedly exposed onto the wafer 59 for each chip. Therefore, the foreign matter 49 present on the reticle 71 is commonly exposed to all the chips on the wafer 59, and a defect 72 common to all the chips occurs. For this reason, a device for inspecting foreign matter on a reticle is required to have strict performance. LSI microfabricated according to the conventional 2μm rule,
For example, in a 256 Kb DRAM, a foreign object inspection device on a reticle is required to have the ability to detect foreign objects with a diameter of 2 μm or more. However, LSIs processed according to today's 1.3 μm rule and future 0.8 μm rule, such as IMb D R
For AM and 4Mb D RAM, respectively φ
Inspection equipment is required to detect foreign particles with a diameter of 1 μrn and a diameter of 0.5 μm or more, which is a large difference from the detection ability of conventional technology. In addition, for the purpose of clarifying the problems with the conventional technology, FJ! I inspected 4. As a result, it was found that a flat foreign object 73 as shown in FIG. 12 cannot be detected by the prior art, regardless of its thickness. From the results of the analysis, it is clear that this is because, as shown in FIG. 24, in the case of a flat foreign object 73, scattered light is not generated by the oblique illumination 47, so detection by scattered light is not possible. Became. An object of the present invention is to solve the above-mentioned problems, so that in addition to foreign objects that can be detected using conventional techniques, foreign objects that are so weak that the generated scattered light cannot be distinguished from patterns, and foreign objects that do not generate scattered light can be detected. An object of the present invention is to provide a foreign matter inspection device that can detect carrier-like foreign matter. 〔problem? Measures to solve the problem] To detect minute foreign objects, we have installed a circuit (pattern extraction circuit) that extracts pattern edge parts from the transmitted light detection signal of the sample, and based on that information, detect the presence of foreign objects from the scattered light detection signal. This is achieved by providing a foreign matter determination circuit that discriminates only scattered light to determine the presence or absence of foreign matter. Also,
He discovered that there is a flat region on the Twolier transform surface in which the polarization direction of the diffracted light from the pattern is aligned in one direction, as described in JP-A No. 59-65428. A polarizing filter was placed on the left side of this area, and a spatial filter that blocked 100% light was placed outside this area. Furthermore, the linearly polarized laser and the single-element system are used for the same purpose and configuration as the disclosed technology. With this configuration, diffracted light from the pattern can be blocked and minute foreign objects can be emphasized and detected. Regarding the detection of the flat foreign matter, a flat foreign matter detection circuit that detects the flat foreign matter from the transmitted light detection signal, specifically,
This is achieved by providing a differentiating circuit that emphasizes the edges of foreign objects. In addition, thin film-like foreign matter can be removed from the reticle substrate (material:
Focusing on the fact that substances with different refractive indexes are attached to 5iO2), we designed a structure using transmitted illumination and a phase contrast microscope. With this configuration, it is possible to detect a thin film-like foreign object while highlighting it brightly against the background including the pattern. [Operation] The scattered light detection signal due to oblique illumination includes the scattered light detection signals of both the foreign object and the pattern edge portion. The pattern edge extraction circuit processes the transmitted light detection signal and extracts pattern edge portions on the photomask. The foreign matter determination circuit removes the scattered light detection signal from the pattern edge portion from the scattered light detection signal based on the butter/edge portion information, and then determines whether foreign matter has been detected. This makes it possible to detect minute foreign objects regardless of the scattered light from the pattern edges. The flat foreign object detection circuit performs differential processing on the detection signal generated by transmitted light illumination, emphasizes the edges of the foreign object, and then makes a determination as to whether the foreign object is detected. Foreign matter can be detected stably. As a result of further progressing the analysis in Proceedings of the Society of Automatic Control Engineers, Vol. 21, No. 8, "LS ■Analysis of reflected light from wafer patterns" (pages 86 to 92), we found that It has been found that there is a region where the polarization direction of the diffracted light is aligned in one direction. If a polarizing filter is installed in this region in a direction that does not allow polarized light to pass through, the diffracted light from the pattern edges will not pass through. On the other hand, reflected and scattered light from a foreign object becomes a light beam having various polarization directions, and therefore passes through this polarizing filter. Furthermore, since light is blocked in areas other than this area by 100% light-blocking spatial filters, only the scattered light from minute foreign objects reaches the rear side of these two filters. Only minute foreign matter is highlighted and imaged by the imaging optical system, and then detected. Since a thin film-like foreign object is a thin film of metal or dielectric material, the phase of the light that passes through it is slightly different from the phase of the light that passes through a part without the foreign object. Therefore, by using a phase-contrast microscope to reduce the amplitude of light that has passed through a portion of the Fourier transform surface where there is no foreign object and to delay the phase by π/4, it appears that the light is reaching only from the foreign object. In other words, only the thin film-like foreign matter can be emphasized and detected. [Example] Hereinafter, specific examples of the present invention will be described using FIGS. 1 to 19. (1) Configuration FIG. 1 shows an example of the overall configuration of the present invention. The present invention
Stage 1. Stage, drive system 2. A sample stage section 4 consisting of a clamp 3, an oblique illumination section 9 consisting of a polarized laser 5° beam expander 6, a condensing lens 7, and an incident angle setting means 8, an objective lens 10, and a half mirror 11. , IJ Sirens 12φ38, Analyzer 13. Interference filter 14. Spatial filter 26 and -dimensional solid-state image sensor 15. Diffused light detection unit 1 consisting of a signal amplifier 42
6 and a mercury lamp 17. Ring aperture 28. Condenser lens 18. A transmitted light illumination section 21 composed of an interference filter 19 and a condensing lens 20, and an objective lens 10. Relay lens 12, 399 phase plate 27° interference filter 40. - A transmitted light detection section 22 composed of a -dimensional solid-state image sensor 41, and a pattern portion extraction circuit or a specific pattern extraction circuit 23, which will be described later. Blocky foreign matter determination circuit 24. Transmitted light detection signal differential enhancement circuit 25° flat particle foreign object determination circuit 30. Stage control system 31, CRT display 32.7' printer 3
3. Side leg portion 3 composed of a microcomputer 34
It consists of 5. (2) Relationship between components The relationship between the components within each component will be explained below. In the sample stage section 4, a photomask 36 is placed on the XX stage 1.
is fixed by the clamp 3. XX stage 1 is
In addition to the photomask 36, the surface to be inspected is placed on the pellicle film 37 (
This is a transparent thin film for preventing foreign matter from approaching the photomask 36, and is described in detail in Japanese Patent Laid-Open No. 59-65428. ) It has a mechanism for positioning in the Z direction so that it can be moved upward. The X stage has a uniform acceleration time of approximately 0.1 seconds, uniform motion of 0.1 seconds, and uniform deceleration time of 0.1 seconds with a half period, maximum speed of 1 m/second, and amplitude of 200. Do the periodic movements of the dragon. The X stage is synchronized with the uniform acceleration time and uniform deceleration time of the X stage, and feeds in one direction in steps of 0.15 fiil. If 670 steps are sent for one test, approximately 13
You can send 100 battles in 0 seconds. With this configuration, an area of 100 x 100 txy can be inspected in about 130 seconds. In the oblique illumination section 9 , the letter light emitted from the linearly polarized laser passes through the beam expander 6 and the condensing lens 7 and enters onto the photomask 36 . The incident angle t at this time is set by the incident angle setting means 8. Photomask 3
The light scattered on 6 enters the scattered light detection section 16 and enters the objective lens 10. Half mirror 11 through relay lens 12
reflect. and an interference filter 14 for blocking transmitted illumination light. Spatial filter 26. It passes through the analyzer 13 and is imaged onto the one-dimensional solid-state imaging (# element 15) by the relay lens 38. The detected signal is amplified by the signal amplifier 42 and guided to the foreign object determination circuit 24 of the control section 35. Fig. 2 shows how scattered light is detected by oblique illumination. In Fig. 2 (4), the detector is a single-type detector 29. In Fig. 2 (b>), the detector is This is a parallel type solid-state image sensor array 43.The light receiving part of the solid-state image sensor array is a silicon photodiode or a GaAJP photodiode, and among these, the PTN junction type has particularly high-speed response and high sensitivity characteristics. , is most suitable for the application of the present invention. FIG. ), if a foreign object passes through the dead zone, it is possible to detect a dog foreign object 45 that is larger than the width of the dead zone, but a minute foreign object 44 shown in FIG. 3(b) cannot be detected. Therefore, this problem is solved by using a solid-state imaging device array of parallelogram pixels as shown in FIGS.
Double counted. However, as a way to avoid this double counting,
6-118187, JP-A-57-66345 and % Kaimei 5
The method described in JP-A-6-126747 and JP-A-56-118647 may be used. In FIG. 4(α), when the scattered light detector 50 scans the pattern edge 48 and the lumpy foreign object 49 that have been obliquely irradiated 47, the detection output vO by the detector 50 is as shown in FIG. 4(b). Change. Therefore, as the result of scattered light detection, the maximum value Vα of the changed detection output shown in FIG. 5 (α) is adopted. As a method for recognizing the maximum value Vα, there is a method in which the scattered light output value at the time when the differential output vO of the scattered light output changes from positive to negative as shown in FIG. 5(b) is set as the maximum value, and A certain interval t as shown in Figure CC)
A method of performing peak hold that requires a reset every time, and setting the scattered light output value Vb;r to the maximum value at the time of reset,
A conceivable method is to carry out a peak hold that is reset when the value falls below a certain threshold, as shown in FIG. In FIG. 2, oblique illumination is performed by an S-polarized laser 5, and its incident angle i is as described in JP-A-59-82727.
It is set so as to avoid interference with the pellicle frame attached to the photomask. The scattered light is transmitted through the objective lens 10.
P analyzer 13. Relay lens (not shown)
The image is then projected onto the detector. In this foreign matter inspection device, the polarized laser 5. Analyzer 13 and spatial filter 26
is not required, but by using each, −
Stabilization of layer detection becomes possible. FIG. 6 shows the magnitude of scattered light from the pattern edge with respect to the pattern angle. The pattern angle here refers to the pattern angle shown in Fig. 5 when the photomask is viewed from above.
is the direction of oblique illumination, and 48 in the same figure is the pattern edge,
θ is the angle that is created. In Figure 6, in addition to the scattered light output from the pattern edge, φ
Scattered light detection outputs V2j) + vi, o and VO5 from standard particles of 2 μm, φ1 μm, and φ0.5 μm are also shown. According to this, when considering the detection of standard particles up to φ0.5 μm, it is impossible to distinguish between a pattern with a pattern angle θ = 1 cf ~ 30° (hereinafter referred to as a specific pattern) and foreign matter by detecting only the size of scattered light. It can be seen that it is. The foreign object detection/judgment method for this purpose will be described next. FIG. 7 shows an isolated large foreign object 7α, an isolated φ0.5 μm foreign object 7b, and a φ0.5 μm foreign object 7 in contact with a non-specific pattern.
c. The detection outputs of scattered light from the φ0.5 μm foreign object 7d, the non-specific pattern 7#, and the specific pattern 7f, which are in contact with the specific pattern, by irradiation with the S-polarized laser 5 are shown. Same figure vH,
Two thresholds are set like vL. Here, if a scattered light detection output exceeding (VH) is obtained, it is a large foreign object 7α or a foreign object 7d that is in contact with the specific pattern, and therefore it is determined that there is a foreign object. (2) If a scattered light detection output that does not exceed vL is obtained, it is determined that there is no foreign object. (2) If a scattered light detection output between vH and vL is obtained and no specific pattern is recognized, it is determined that there is a "foreign object". ■vH and v
If a scattered light phase detection output in the middle of L is obtained and a specific pattern is recognized, it is determined that there is no foreign object. From this, the foreign object detection result, together with the specific pattern extraction result P, is D=(V□≧Va)IJ((Vo<Ha)l”1(Vo
≧VL)nP). FIG. 8 shows a circuit example of the above algorithm. The output vO of the scattered light detection section 16 is compared with the threshold value vH by a comparison circuit 51. It is input to the comparison circuit 52 with the threshold value vL. The output of the comparison circuit 51 with the threshold vH is input to the OR circuit 56 and the NOT circuit 54. - direction, transmitted light detection section 2
The output of 2 is inputted to the specific pattern extraction circuit 23. The output P of the specific pattern extraction circuit 23 (which outputs 1 when a specific pattern is extracted) is inverted by the NOT circuit 53 and input to the AND circuit 55 . The AND circuit 55 also receives the output of the comparison circuit 52°NOT circuit 54 with the threshold value vL. The output of the AND circuit 55 is input to the OR circuit 56. FIG. 9 shows the scattered light detection output Vθ, the scattered light detection output vop from a φ0.5 μm standard particle, the threshold values vL, vHl, and 0 for a pattern with a pattern angle θ of 0 to ±4 degrees.
Scattered light detection output ■θ+VO5 when a φ0.5 μm standard particle is close to a pattern of ° to ±4 f is shown. In the pattern and foreign object discrimination using the above-mentioned algorithm, the 9th
ΔvH in the figure is a margin to avoid incorrectly detecting a pattern. Also, ΔvL is a margin to prevent a foreign object from being overlooked. Here, if ■os is 1, Δ■H1ΔvL is approximately 0. 25. The above algorithm and circuit make it possible to detect minute foreign objects, but the following describes an algorithm for more stable detection by increasing ffH and ΔvL.A pattern has a unique strength depending on its pattern angle θ. The scattered light of ), the threshold value vM is changed as shown in Fig. 10. ■If Vo≧vM, it is determined that there is a foreign object.■Vo<
In the case of vM, it is determined that there is no foreign object. In this algorithm, Δ■L and ΔvH are as shown in Figure 10, and VO
When 5-¥1, the ratio is approximately 0 for both ΔVL and ΔvH.
．． It becomes 5. Therefore, compared to the previous algorithm, 2
Detection with twice the margin becomes possible. A circuit example of this algorithm is shown in FIG. Output Vo of the scattered light detection section 16
is input to the comparison circuit 58 with the threshold value vM. The output of the transmitted light detection section 22 is input to the pattern portion extraction circuit 23. The pattern portion extraction circuit 23 recognizes the pattern angle θ of the input pattern, and sets θ to the threshold value vM generation circuit 5.
Output to 7. The output vM of the threshold value ■M generation circuit 57 is v
It is input to a comparison circuit 58 with M. A method for extracting a specific pattern will be described in FIGS. 12 to 17. A possible method for extracting patterns is to perform pattern matching on images that are used as specific patterns in transmitted light illumination images, but in order to extract specific patterns with high precision, this method requires , the pixels need to be made very small. Therefore, the number of times the sample is scanned increases and the inspection time becomes longer. For example, 0.5μ
When detecting m-objects using 0.5 μm pixels, it takes 46 minutes to scan 100×100 pixels due to the limitations of the sample scanning table and the operating speed of the detector. A method for extracting a specific pattern with high resolution using larger detector pixels will be described below. As shown in FIG. 12(a), the rectangular pixel 63 of the photodetector
When a pattern edge 48 exists within a square pixel (which may also be a square pixel), the photodetector is located at an average position 64 (detector pixel 63) of the pattern edge 48 with respect to the long side direction of the detector pixel 63, as shown in FIG. Detection output value Vo” corresponding to the position of the pattern edge on the center line in the short side direction
Indicates A/A+B. Therefore, by using a plurality of detectors as shown in FIG. 12(C), it is possible to recognize the angle θ of a pattern edge existing within a detector pixel. As described above, this method is capable of extracting a specific pattern with high resolution even when using large detector pixels, and is suitable for high-speed foreign object inspection. FIG. 13 shows an example of extraction using this method. 13α is a transmitted light illumination image obtained by scanning parallel detectors or a single detector. 13h shows a pixel of interest 65 for recognizing the pattern shape and its surroundings cut out from 13α with 3×3 pixels. 13C is 13
The detection output value of each pixel at h is shown, and each detection output value is normalized to ℃ with the saturation output value of the detector set to 100. 13d is the result of adding the detection output values of 13C for three pixels in the X direction. This result is shown in Figure 12 (
Corresponds to bl. The pattern angle θ is determined from the sum of the two sets of three pixels adjacent to each other. 13L is the pattern angle calculated from the addition result of 13d. By calculating the pattern angle from the pixels in the upper two columns and the lower two columns, it is also possible to determine when a pattern angle exists in the pixel of interest, as shown in FIG. In this method, the first
In contrast to FIG. 2(α)K, if the pattern edge 48 crosses the longitudinal direction of the detector 63 as shown in FIGS. 15(α) and (b), the calculation result will be inaccurate. For this reason,
In addition to the pattern angle θl obtained from the result of adding 3×3 pixels in the X direction, the pattern angle θ2 is also calculated from the result of adding 3×3 pixels in the Y direction, and the calculation result θl is obtained. θ2 is O degrees≦101,21 <4s degrees and 135 degrees≦1
01 if θ1,21<180 degrees, and 45 degrees≦10
When 1,2 l <135 degrees, 02 is determined as the pattern angle θ. Furthermore, as shown in Fig. 16 (α) and (b), the same detected value can have two different states, so in Fig. 13, the sum of the rightmost F13 pixel and the leftmost vertical 3'#J pixel is calculated. Compare, and if the left end is larger (brighter), the first
If the right end of Figure 6 (α) is larger (brighter), it is determined that the state is in Figure 16 (h) (Vo=:A/
A+B, (,'/C+D). From the above, when the detector outputs Vll to V33 are obtained at the detection pixels of Q<, pH to P33 in FIG. 17, the pattern angle θ at the pixel of interest P22 is as follows. Note that the pattern extraction method can be applied not only to the transmitted light detection method but also to other illumination methods. Next, the effect of the spatial filter 26 in FIG. 1 will be described. In FIG. 1, in the oblique illumination section 9, a linearly polarized laser 5
is fixed by the incident angle setting means. The light emitted from the linearly polarized laser 5 passes through the beam expander 6 and the condensing lens 7 and enters the photomask 36 at an angle of incidence. The light reflected and diffracted by the photomask 36 is transmitted through the objective lens 10. The light is designed to be focused on a spatial filter 26 through a relay lens 12. That is, a beam expander 6° condensing lens 7, an objective lens 10. A real image of the light source of the linearly polarized laser 5 is formed on the spatial filter 26 through the relay lens 12 . With this configuration, seven Raunhoft and seven diffraction images of the pattern 48 on the photomask can be formed within the plane containing the spatial filter 26. Further, the direction of polarization of the light beam 74 is perpendicular (P polarization) or parallel (S polarization) to the plane of incidence (plane including the light beam 74 and the optical axis 75). However, in terms of device design, the above configuration may not be adopted and the configuration shown below may be used approximately. That is, the diameter of the light beam incident on the condenser lens 7 is set to about 0.5 to 2 ms,
The distance Lp from the condenser lens 7 to the photomask 36 is 30
~100111, and an image of the light source is formed on the photomask 36. Furthermore, when only the objective lens 10 and the relay lens 12 are considered, a spatial filter 2 is placed on the Fourier transform surface.
Install 6. In this configuration, since the light beam irradiated onto the photomask 36 is close to a parallel light beam, it can be approximately considered that the light beam is actually Fourier transformed only by the objective lens 10 and the relay lens 12. Further, in this case, the illuminated portion on the photomask 36 becomes an inertia circle, and its minor axis length αt is determined by the following formula. αl = 1.22・λ・Lp/dp...
(1) Here, λ is the wavelength of the irradiated light. This αt should be determined based on the light intensity required for detection and the size of the object to be illuminated. In this example, ctp=1, Lp=500, and Li=40t.
It is set as trn. In the scattered light detection section 16 , the pattern 48 and foreign matter 49 on the photomask 36 are imaged onto the one-dimensional solid-state image sensor 15 by the objective lens 10 and the relay lens 12 . Here, a spatial filter 26 is installed on the imaging plane of the beam expander 6, condensing lens 7, relay lens 12, and objective lens 10 of the light source of the linearly polarized laser 5. Further, an analyzer (polarizing filter) 13 is also installed at this position. The analyzer 13 is oriented in a direction that blocks the light beam of the linearly polarized laser 5. Specifically, the polarization axis is set perpendicular to the incident plane when S-polarized light is incident, and parallel to the incident plane when P-polarized light is incident. Here, the analyzer 13 may be placed at any position between the photomask 36 and the -dimensional solid-state image sensor 150 instead of the above-mentioned position. Further, the spatial filter 26 may be located between the photomask 36 and the objective lens 10 and immediately in front of the objective lens 10. This is the light beam 74 produced by the linearly polarized laser 5.
is approximately parallel light, and the pattern 48 on the photomask is minute, so a Fraunhogh diffraction image can be obtained without using the objective lens 10 or the like. However, if a flat foreign object is also to be detected, it is better not to enter the flat foreign object detection section. Although it is not necessary to use the relay lens 12, in reality, a collective lens is often used as the objective lens 10, and the imaging position of the light source of the linearly polarized laser 5 by the beam expander 6, condensing lens 7, and objective lens 10 is Objective lens 10
It may be inside. In this case, the relay lens 12
A spatial filter 26 should be installed at the imaging position after passing through. Furthermore, a Fourier transform lens can also be used as the relay lens 12. At this time, since the Fourier transformed image of the pattern 48 becomes sharp, the light from the pattern 48 can be effectively blocked by the spatial filter. The interference filter 14 can block the illumination light from the transmitted light heat bright section 21, and only the light from the linearly polarized laser 5 can be detected. Next, the shape of the spatial filter 26 will be explained using FIGS. 74 to 88. This shape should be optimally designed depending on the illumination method and polarization method of the illumination light. First, the behavior of illumination light will be explained. FIG. 74 is an enlarged view of the photomask 105. direction 14
A pattern 107 having edges 147 parallel to 8 is formed on a photomask substrate 146. pattern 107
is made of chromium oxide, and the substrate 146 is made of 5 iOz. FIG. 75 shows illumination light 1 when illuminating a photomask.
55 and direction 148 by pattern 107 [159
, 160 and an aperture 164 of an objective lens. Polarization direction is indicated by arrow 158, 162°163
It is shown by . Also, assuming a spherical surface 165 in contact with the aperture 164 of the objective lens 10, the polarized lights 162 and 163 of the diffracted lights are shown on the intersections 161 and 198 of the diffracted lights 159 and 160 and the spherical surface 165, respectively. Indeed, the curve including these intersection points 161 and 198 becomes a circle 166. FIG. 76 is a plan view of FIG. 75. pattern direction 1
Circle 1 including the intersection of the diffracted light and the spherical surface 165 when changing 48
66 is indicated by straight lines 199-202. Further, the intersections of the incident light 156 and the outgoing light 157 with the spherical surface 165 are indicated by points 205 and 157, respectively. Here, the polarization direction of reflected light of linearly polarized light incident on a substance with a refractive index l at an arbitrary incident angle i is determined by the following equation. (From "Analysis of reflected light from LSI wafer pattern") (Rs, Rp) = (S(g)Es, P(
i) Ep) ・−・−−−−−−−−−(2) Here, Es and Ep are the intensities of the S polarized light component and P polarized light component of the reflected light, respectively, and Rs and Rp are the intensities of the S polarized light component and the P polarized light component of the reflected light, respectively. . Further, S (t) and P (t) are determined by the following formulas. Using this equation, the polarized light 162 at the intersection 161 of the diffracted light 159 when P-polarized light (linearly polarized light having an electric field vector parallel to the plane of incidence) is incident is calculated. In this case, in FIG. 74, the edge 47 of the pattern 107 is a plane 149,
50 and 151, and reflection on each plane is considered. That is, the planes 149 to 15
The direction and polarization direction of the reflected light of the light incident on 1 at the incident angle t are calculated using equation (2), and this is calculated as the direction of the diffracted light 159 and the polarization direction of the light 159.
It is set at 62. This result is shown in FIG. 76 by the arrow of polarization direction roller 2. Hereinafter, blocking of diffracted light from the pattern will be explained. The I section of the diffracted light from the pattern has an incident angle of 1550, and a spatial filter 26. Three elements of the analyzer 13 are used to effectively block the light. According to FIG. 76, the source diffracted into the range 167 does not enter the lens aperture 164. That is, these diffracted lights are blocked by setting the incident angle of the illumination light. When the incident angle variable is made large, the emission point 157 moves away from the lens aperture 164 and becomes the emission point 174, so the range 167 of the diffracted light that can be blocked becomes the range 206, and a wider range of diffracted light can be blocked. By setting this incident angle i, a circle 16 indicating this diffracted light
6, that is, the pattern in the direction 148 perpendicular to
(The diffracted light from the pattern having the direction of the range 171 shown can be blocked. Next, in FIG. 76, it can be seen that the foil light within the range 168 is approximately parallel to the incident plane. The polarization directions within ranges 169 and 170 are not parallel. Therefore, the diffracted light incident on range 168 is blocked by polarizing filter 13: (furthermore, ranges 169 and 17
The diffracted light incident on the 0 is blocked by the spatial filter 26. The shape of the spatial filter 26 is shown in FIG. Light shielding part 175. It is formed by a transparent section 176. Here, the edge 208 of the spatial filter 26 is curved because the lens aperture 164 is a plane, and the set of points where the diffracted light 159 intersects with the lens aperture 164 forms a curve. Since the lens aperture 164 is a Fourier transform surface,
Just consider the shape here. That is, spatial filter 2
6 may be designed to have a similar shape by considering the state of diffracted light on the lens aperture 164. However, it should be noted that the opening 164 is a flat surface. What is incident on range 168 is the diffracted light from the pattern having the direction in range 172, and what is incident on ranges 169 and 170 is the diffracted light from the pattern having the direction in ranges 173 and 174. The above three elements (incident angle i, polarization filter 13° and spatial filter 26) block diffracted light from the nodules having all directions. On the other hand, the polarization direction of the scattered light from the foreign object is not aligned in one direction like the above-mentioned diffracted light, so the range 168
Since polarized light in directions other than direction 209 is also incident on these filters, it is not blocked by these filters.An analysis of the polarization direction of scattered light from foreign objects is described in Born &Wolf's Pr.
1 ciples of 0ptics, pages 652 to 656. Similarly, FIG. 78 shows the polarization direction of diffracted light when S-polarized light (linearly polarized light having an electric field vector perpendicular to the plane of incidence) is incident. In this case, the same spatial filter as shown in FIG. 77 blocks the diffracted light incident on ranges 178 and 210, and the diffracted light incident on range 177 rotates the analyzer by 90 degrees in the case of FIG. It is shut off by something installed. Further, FIG. 79 shows the polarization direction 211 of the incident light and the polarization direction 212 of the diffracted light when the light is incident perpendicularly. In this case, the range 179, 180, 181, 18
The diffracted light incident on 2 and 187 is filtered through the spatial filter 26
185, 186, 187 and 18
The diffracted light incident on the analyzer 8 may be blocked by the analyzer 13. Moreover, it has been found through experiments that when the incident angle of the light beam of the linearly polarized laser 5 is set to about 60 degrees, the reflected light from a pattern having a pattern angle θ of about 23 degrees is strong. Therefore, it is preferable to use a spatial filter having a shape as shown in FIG. This filter can effectively block the diffracted light from the 2f pattern and allow more of the scattered light from foreign objects to be taken in. Furthermore, it has been found through experiments that the larger the angle of incidence, the greater the amount of light scattered from foreign objects. The photomask 105 is a transparent thin film as shown in FIG.
g A foreign matter adhesion prevention device (pellicle) consisting of a (pellicle membrane) 136 and a frame (pellicle frame) 137 for holding it may be used. In this case, if the incident angle LtX is set to a large value, a region 139 will be created that is blocked by the frame 137 and cannot be illuminated. Here, by using a configuration in which an oblique illumination section 120 having the same configuration as the oblique illumination section 9 is also used as illumination from the side rotated by 1800 degrees, this area is illuminated to enable inspection. In this case, as shown in Figure 84,
The origin is separated by a noof mirror 188, and a spatial filter 189. Analyzer (polarizing filter) 190 , interference filter 191 . Relay lens 110. - dimensional solid-state image sensor 192 is added, and the spatial filters 26 shown in FIG.
When inspecting the region 139 using the cf rotation, the detector 192 inspects the area by illuminating the light beam 141. This eliminates uninspectable areas. Of course, in this uninspectable area, the reticle 5 is
It is also possible to inspect by rotating it. In addition, the wavelengths of the light sources of the oblique illumination unit 12 and the oblique illumination unit 220 are changed, and the wavelengths of the light beams 155 and 219 are set to λl, respectively. λ2 and a wavelength separation mirror is used instead of the half mirror 188, and λ1. A configuration in which λ2 is separated may also be used. According to this method, there is no need to switch the light source. Furthermore, these two-way illuminations have other effects as well. As shown in FIG. 74, actual minute foreign matter is not symmetrical. The intensity, polarization, etc. of the scattered light differ between the illumination by the light beam 155 and the illumination by the light beam 219 due to the difference in size and shape of the reflecting surfaces 221 and 222. In such a case, there is a risk of false detection if only the - side is illuminated, whereas in the case of bidirectional illumination, in the area 220 in Fig. 83 where two lights are irradiated at the same time, either side can be detected. There is a high possibility that the detection reliability will be improved.Also, using the spatial filter shown in FIG. Using the results, it is possible to partially change the direction of the analyzer to effectively block the reflected light from the pattern 107, as shown in FIG. If the value changes drastically, it cannot be approximated, so a light shielding plate may be used in combination.
It is sufficient to perform calculations using equation (2) and redesign the combination of polarizing plates 213. In addition, although the illumination means has been explained using S-polarized light or 2g4 element, it is possible to
．． It is possible to design a polarizing filter that effectively blocks reflected light from a pattern for linearly polarized illumination of any polarization. Further, the actual pattern 107 of the photomask 105 may be a combination of only patterns with θ=0° and 90', as shown in FIG. In this case, a spatial filter as shown in FIG. 88 may be installed to block light scattered from the pattern at .degree. C. and .theta.=0.degree. by means of a light blocking portion 175. It has already been explained that the scattered light from the pattern of θ=90° due to oblique illumination does not enter the objective lens 10. The intensity of the scattered light from the corner portion 223 of the pattern is negligible. The polarization direction of the incident light, the angle of incidence, the shape of the spatial filter, and the orientation of the polarizing filter should be designed based on the above concept. Detection of a flat foreign object will be described using FIG. 1 and FIGS. 18 to 22. In the transmitted light illumination unit 21 of FIG. 1, the light exiting the transmitted light illumination unit 17 such as a mercury lamp or a xenon-mercury lamp is transmitted to a ring diaphragm 28. Condenser lens 18. Wavelength selection filter 19. The light passes through the condensing lens 20 and is irradiated onto the photomaster. The ring diaphragm is used only when constructing a phase contrast microscope, which will be described later. Transmitted light transmitted through a photomask 36 is condensed by an objective lens 10, and is condensed by a relay lens 12. Half mirror 1
1. Interference filter 409 and phase plate 27 for separating scattered light and wavelength. The image passes through a relay lens 39 and is imaged onto a one-dimensional solid-state image sensor 41 . The phase plate is used only in the platform that constitutes the phase contrast microscope described later. The detected transmitted light image is sent to a transmitted light detection signal differential enhancement circuit 25 for emphasizing flat foreign matter, and is discriminated from a pattern by a flat foreign matter determining circuit 30 to detect the foreign matter. In addition, foreign matter with low light-shielding properties may cause multiple interference inside when transmitted light passes through it, reducing the amount of transmitted light. Since this phenomenon is caused by light interference, the situation in which it occurs changes depending on the wavelength of the transmitted light. Therefore, in order to discover harmful foreign substances during exposure,
It is necessary to make the transmitted light for inspection the same wavelength as the exposure light. Therefore, the transmitted light illumination section 21 uses the same light as the exposure light. A filter 19 is provided to select the desired length. The differential emphasis circuit 25 for the transmitted light detection signal will be explained. As shown in FIG. 18, the foreign matter on the photomask 36 has a high
In the case of 0, the light intensity distribution I on the wafer 59 becomes significantly small, and as a result, the highly light-shielding foreign matter 60 has a large influence on the transfer. On the other hand, when the foreign matter on the photomask 36 has a low light-shielding property 61, the light intensity distribution on the wafer 59 does not become smaller than when the foreign matter 60 has a high light-shielding property. Therefore, the influence of the low light-shielding foreign matter 61 on the transfer is smaller than that of the high light-shielding foreign matter 60. However, even if the material constituting the foreign material has low light-shielding properties, if the foreign material has minute irregularities or edges,
Experiments have revealed that foreign matter has a greater effect on exposure. This is because, as shown in FIG. 19, the exposure light (transmitted light) 69 causes diffraction 70 at the minute irregularities and edge portions 68, and as a result, the amount of transmitted light vT decreases. Therefore, in the case of foreign substances with low light-shielding properties, it is necessary to detect minute irregularities and edges by making them obvious. Possible methods include configuring the transmitted light detection system 22 with a phase contrast microscope, or electrically differentially processing the transmitted light detection signal. As shown in FIG. 19(h), when the transmitted light detection signal vT is subjected to differential processing IVT'l, minute irregularities occur. The edge portion 68 is exposed. Next, we will discuss the discrimination between foreign objects and patterns. Figure 18) shows the pattern 48 on the photomask 36, a large flat foreign matter 66 with low light shielding property, and a small flat foreign matter 67 with high light shielding property. Since the pattern 48 is formed of a highly light-shielding metal film, the detection output by transmitted light illumination is extremely small. In addition, FIG. 18 (A1-(et)) is a detection signal vT obtained by transmitted light illumination in FIG. 18 (α). In FIG. It is impossible to discriminate the detection signal by a threshold value. Fig. 18 (C) shows the detection result using an optical system with a lower resolution than that shown in Fig. 18 (d). These are detection results using a detector with larger dimensions than those in Figure (A).In both cases, the resolution of the detection system is low, and the detection signal vT due to the highly light-shielding flat foreign object 67 is the detection signal vT due to the pattern 48.
Mase doesn't get low. For this reason, the threshold ■yu,■! By setting , it is possible to distinguish between patterns. In this way, from the signal Vp (FIG. 18(e)) obtained by binarizing the transmitted light detection signal using an appropriate resolution and threshold value, a signal VM (FIG. 18(a)) is generated by pixel-enlarging the signal Vp (FIG. 18(e)). By performing mass-young processing on the signal IVT'l obtained by differentially processing the transmitted light detection signal vT using this vM as shown in FIG. can. FIG. 22 shows the configuration of the peace-like foreign object detection circuit 30. The detection signal vT obtained by the transmitted light detection circuit 71 is differentially emphasized by the differential emphasis circuit 25 (lVT'l)
. - On the other hand, vT is compared with a threshold value vrL or vg in a comparison circuit 77, and the pattern portion is recognized. (Vp). A pixel enlarging circuit 78 enlarges vp and generates a masking signal vM. Then, vM passes through the inversion circuit 53 and is ANDed with lVT'l by the ANT) circuit 80 to obtain the transmitted light differential emphasis signal Vs from which the influence of the pattern has been removed. Vs is compared with a threshold value Vk in a comparator circuit 79 to obtain a foreign object detection signal. Next, a case where the transmitted light detection section is configured as a phase contrast microscope will be described. In FIG. 1, in the transmitted light illumination section, light from a light source 17 illuminates a ring diaphragm 28 having an annular opening. The light emitted from the ring aperture passes through the condenser lens 18. Interference filter 19. Photomask 3 through condensing lens 20
6 from the back side, objective lens 13, relay lens 1
2. An interference filter 401 that blocks light from the half mirror 11 and the oblique illumination section 9! through which an image is formed on the phase plate 21. Since phase contrast microscopy steel is explained in many documents, the explanation will be omitted here. (Example: Written by Kubota, Applied Optics, Iwanami Zensho, pages 129 to 136) The flat foreign matter that can be detected by this detection system is one with a phase difference of 10nr or more of 4 degrees. Furthermore, even if the foreign material is thick, a phase is generated due to the non-uniformity of the foreign material, making it possible to detect it. Therefore, in practice, it is possible to detect foreign objects of any thickness from 10 lumens to several μm. In a configuration using a phase contrast microscope, only the part where a phase difference occurs, that is, the part where a foreign object is present, becomes bright and can be detected.In this case, there is no need to recognize the pattern part as described above, and the device configuration is It has the feature of being simple. (3) Block diagram of device configuration The above invention is configured as shown in the block diagrams of FIGS. 25 to 72 below. In FIG. 25, a sample 36 is illuminated by transmitted light illumination 21 for detecting transmitted light and oblique illumination 9 for detecting scattered light. The transmitted light stage is photoelectrically converted by a transmitted light detection system 22. The flat foreign matter detection circuit 83 performs processing such as differentially enhancing the transmitted light detection signal as necessary, and ejects flat foreign matter. The scattered light image is photoelectrically converted by the scattered light detection system 16. A lumpy foreign object detection circuit 93 detects a lumpy foreign object from the scattered light detection signal. The detected flat foreign matter and lumpy foreign matter are displayed on a foreign matter display device 82 after the overlap between the results of the two detection systems is removed by an OR circuit 81. 26th
The configuration of the figure is the same as that shown in FIG.
A block foreign matter display device 85 is provided to display the detection results before entering the OR circuit 81. The configuration shown in FIG. 27 is based on the configuration shown in FIG. 25 (the pattern extraction circuit 23f!!: provided) and the flat particle foreign object determination result of the flat foreign object determination circuit 86 (including the differential emphasis circuit 25 if necessary). , pattern partial inhibit circuit 8 for detecting transmitted light
In step 7, false alarms from the pattern portion are inhibited, and based on the judgment results of the blocky foreign object determining circuit 88, a pattern portion inhibiting circuit 89 for detecting scattered light inhibits false alarms due to scattered light from the pattern portion. be. The configuration of FIG. 28 is the same as that of FIG. 26, but also includes a pattern extraction circuit 23, a pattern portion inhibit circuit 87,
89. In the configuration of FIG. 29, the configuration of FIG.
It was set up after the , whereas it was set before. The configuration shown in FIG. 30 is different from the configuration shown in FIG.
It was provided after 8, whereas it was provided before. 101 is provided to optically inhibit the detected image from the pattern portion. The configurations shown in FIGS. 31 and 32 include the configurations shown in FIGS. 25 and 26 plus a spatial filter or analyzer for detecting scattered light, or a spatial filter and an analyzer 96, a light source 94 for a phase contrast microscope, and a phase difference A spatial filter 95 for a microscope is provided to optically inhibit the detected image from the pattern portion. The configuration of FIGS. 33 to 36 is the same as the configuration of FIGS. 27 to 30 by adding a spatial filter or an analyzer or a spatial filter and analyzers 95 and 96, and pattern extraction circuit 23. stomach. When used together with the bit circuits 87 and 89, the detection signal from the pattern portion is inhibited both electrically and optically. No. 37, 38, 40, 41, 43, 44, 46, 47.
The composition of figures 49, 50, 52, and 53 is as follows from figures 25 to 36.
A stage 1 for scanning a sample 58 and a drive system 2 thereof are provided in the configuration shown in the figure. The result of foreign object detection is displayed on the foreign object display device 82 together with the coordinates of the stage obtained from the drive system 2, that is, the coordinates of the detected foreign object. The configurations shown in FIGS. 39, 42, 45, 48, 51, and 54 are those shown in FIGS. However, the coordinates of the stage are determined by the OR circuit 8.
1, together with the foreign matter detection results, the flat foreign matter display device 8
4, or the detection result and the coordinates of the foreign object are displayed on the lump foreign object display device 85. The configurations shown in FIGS. 55 to 72 have means 1 and 2 for scanning the sample 58, whereas the configurations shown in FIGS. 37 to 54 have means 1 and 2 for scanning the detection system 90. Blue mechanism 91.
It has a detection system scanning drive system 92. [Effects of the Invention] As explained above, according to the present invention, a pattern can be recognized using a transmitted light signal of a photomask, and scattered light from a foreign object and scattered light from a pattern can be distinguished, which is impossible with conventional technology. This has the effect of making it possible to detect submicron foreign objects. Further, according to the present invention, the edge portion of the flat foreign object can be emphasized by performing differential processing on the transmitted light signal, so that it is possible to detect the flat foreign object, which is impossible with the prior art.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2 is a perspective view of foreign object inspection, Fig. 3 is a plan view of the detector and foreign object, Fig. 4 is a side view of foreign object detection, and Fig. 5 is Graph of foreign object detection output,
Figure 6 is a graph of scattered light detection output from the pattern, Figure 7 is a graph of scattered light detection output from the pattern.
The figure is a graph of scattered light detection output from foreign objects and patterns.
FIGS. 8 and 11 are block diagrams of the blocky foreign matter determination circuit, FIGS. 9 and 10 are graphs explaining the operation of the blocky foreign matter determination circuit, FIG. 12 is a plan view of the detector pixel, and FIG. 13 is a block diagram of the blocky foreign matter determination circuit. Algorithm for pattern angle extraction, Figures 14 to 17 are plan views of detector pixels, Figure 18 is a side view of foreign matter transfer, and Figure 1
Figure 9 is a graph of v; Figure 20 is a graph of vT-vP-vM; Figure 21 is a graph of vT - vM - Vs;
The figure is a block diagram of the flat foreign matter determination circuit, Figure 23 is a perspective view of a defect common to all chips, Figure 24 is a side view of oblique illumination,
FIGS. 25 to 72 are block diagrams of the configuration of the present invention, FIGS. 73 and 84 are block diagrams of the lump foreign matter detection system, FIG. 74 is a perspective view of a photomask, and FIG. 75 is a perspective view of pattern diffracted light. 76 and 78 are plan views of pattern diffracted light, and FIGS. 77 and 79 to 81 and 85.
The plan views of the spatial filters in FIGS. 86 and 88 are plan views of the photomask. 1...XY stage, 2...stage drive system,
3... Clamp, 4... Sample stage, 5...
・Linearly polarized laser, 6... Beam exno (nda, 7)
...Condensing lens, 8...Incidence angle setting means,
9... Oblique illumination section, 10... Objective lens, 11
...Half mirror-112...Relay lens, 13.
...Analyzer, 14...Interference filter, 15.
...-dimensional solid-state image sensor, 16... scattered light detection unit, 17... mercury lamp, 1
8... Condenser lens, 19... Interference filter, 20... Condensing lens, 21
... Transmitted light illumination section, 22... Transmitted light detection section, 23
...Pattern partial extraction circuit or specific) turn extraction circuit, 24...Lumpy foreign object determination circuit, 25...Transmitted light detection signal differential emphasis circuit, 26...Spatial filter, 27...Phase plate, 28... Ring aperture, 29... Single type detector, 30... Flat foreign object determination circuit, 31... Stage control system, 32... CRT display, 33... Printer, 34 ...Microcomputer, 35...Control unit, 36...Sample or photomask, 37...Pellicle! , 38... Relay lens, 39... Relay lens, 40... Interference filter, 41... -dimensional solid-state image sensor, 42... Signal amplifier, 43... Parallel solid-state image sensor play, 44... Minute foreign matter, 45... Large foreign matter, 46... Double counted foreign matter, 47... Oblique illumination, 48... Pattern (edge), 49... Massive foreign matter, 50.・
・Scattered light detector, 51...S polarized laser, 52...
・Comparison circuit with vH, 52...Comparison circuit with vL, 53, 54...NOT circuit, 55...3 manual AN
D circuit, 56...2-manual OR circuit, 57...vM generation circuit, 58...vM comparison circuit, 59...wafer, 60...highly light-shielding foreign matter,
61...Low light shielding foreign matter, 62...Exposure lens, 6
3... Rectangular pixel of photodetector, 64... Average position of pattern edge, 65... Pixel of interest for recognizing pattern shape, 6
6...Large flat foreign matter with low light shielding property, 67...Small flat foreign matter with high light shielding property, 68...Irregularities or edges of foreign matter, 69...Exposure light, 70...Diffracted light , 71・
... Reticle, 72... Defect common to all chips, 73... Flat foreign object, 74... Luminous flux, 75...
・Optical axis, 76...Slit, 77...Comparison circuit with Otori and bow, 78...Pixel enlargement circuit, 79...Comparison circuit with VA, 80...AND circuit, 81...・OR circuit,
82... Foreign matter display device, 83... Flat foreign matter detection circuit, 84... Flat foreign matter display device, 85... Massive foreign matter display device, 86... Flat foreign matter determination circuit or flat foreign matter detection circuit. Carrier foreign matter determination circuit and differential emphasis circuit, 87... Pattern partial inhibition circuit for transmitted light detection, 88... Massive foreign matter determination circuit, 89... Pattern partial inhibition circuit for scattered light detection, 90... - Detection system, 91... Detection system scanning mechanism, 92... Detection thread running, drive system, 93... Massive foreign matter detection device, 94... Phase difference type W, mirror light 0. 95... Spatial filter (phase plate) 9 for phase contrast microscope
6... Spatial filter or analyzer for scattered light detection, or spatial filter and analyzer, 105... Photomask, 107... Pattern, 11
0... Relay lens, 120... Oblique illumination section, 13
6... Pellicle membrane, 137... Pellicle frame, 1
46... Photomask substrate, 147... Pattern edge, 155... Illumination light flux, 156... Incident light, 1
57... Emission light, 159, 160... Diffracted light, 164... Objective lens aperture, 175... Spatial filter light shielding part, 176... Spatial filter transmitting part, 188... Half mirror - 118 pieces ...Spatial filter, 190...Analyzer (polarizing filter), 191...
Interference filter, 192...-dimensional solid-state image sensor. 208... Spatial filter edge, 219... Luminous flux of oblique illumination, 220... Two direction irradiation area.

Claims (1)

[Claims] 1. oblique illumination means for illuminating a glass substrate sample having a circuit pattern such as a photomask or reticle; a first photoelectric conversion means for detecting scattered light from the sample by the oblique illumination means; a first foreign object determination means that determines the presence of a foreign object from a detection signal of the photoelectric conversion means; a transmitted illumination means that transmits illumination of the sample; and a second foreign matter determination means that detects the transmitted light from the sample by the transmitted illumination means. A photoelectric conversion means, a second foreign object determination means that determines the presence of a foreign object by differential processing of the detection signal of the second photoelectric conversion means, and circuit pattern information is obtained from the detection signal of the second photoelectric conversion means. A circuit pattern information recognition means for recognizing, and a removal means for removing the recognition result of the circuit pattern information obtained from the circuit pattern information recognition means from the determination results of the first and second foreign matter determination means. Features of foreign matter inspection equipment.