JPS63208746A - Defect inspecting device - Google Patents

Abstract

PURPOSE:To perform inspection without any irregularity in sensitivity by correcting foreign matter information which is detected photoelectrically according to transmissivity characteristics corresponding to the angle of light incidence on a light-transmissive substrate (e.g. pellicle) provided nearly in parallel to a substrate to be inspected (e.g. reticle). CONSTITUTION:Laser light 100 from a laser 11 is made incident on the pellicle 2a through half-mirrors 12 and 13 and a mirror 15 and photodetecting elements 3 and 4 measure the quantities of transmitted light 106 and reflected light 105 respectively. The pellicle 2a is rotated on an axial l1 and light transmissivity and a reflection factor corresponding to an angle theta of incidence are measured and stored. Then laser light passed through the prism 12 and a mirror 19 scans on the reticle 22 with the pellicle 23a through a scanning mirror 20 and a lens 21. Photodetecting elements 25 and 27 detect scattered light from foreign matter on the surface of the reticle 22. Their detection results are corrected with the measured and stored transmissivity according to the angle of light incidence on the pellicle 23a. Then there is no irregularity in sensitivity with the scanning position.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a device for detecting defects existing in masks and reticles used in the manufacture of semiconductor devices, and in particular foreign matter adhering to masks and reticles, and particularly relates to an apparatus for detecting foreign matter attached to masks and reticles, and particularly to an apparatus for detecting defects present in masks and reticles used in the manufacture of semiconductor devices. The present invention relates to a device for inspecting a mask or reticle, or a transparent substrate itself, which is integrally provided with a transparent substrate (polymer thin film or glass plate) for the purpose of protecting the mask or reticle from floating minute dust.

[Conventional technology]

Traditionally, masks and reticles (hereinafter referred to as reticles)
JP-A-58-62543, JP-A-58
One disclosed in Japanese Patent No.-62544 and the like is known. This device scans one-dimensionally in the X direction using, for example, a galvanometer mirror (vibrating mirror) with a focused laser beam spot incident on the reticle surface at an angle of 10° to 45''.
The reticle is moved in the y direction, and among the reflected light generated from the reticle surface, side scattered light, back scattered light, etc. are received by multiple photoelectric detectors placed at specific spatial positions relative to the laser beam irradiation position. By doing so, the presence, adhesion status, size, etc. of foreign objects can be inspected.

In recent years, it has been desired that such an inspection apparatus be capable of effectively inspecting a reticle with a thin polymer film (hereinafter referred to as a pellicle).

[Problem that the invention seeks to solve]

The inventor of the present application has confirmed that the following problems occur when a reticle with a pellicle is inspected as is with a conventional apparatus.

The first point is that when the laser beam enters the reticle from the pellicle side, the laser beam is scanned at oblique incidence, so the incident angle changes depending on the scanning position, and the spot light of the laser beam reaches the reticle surface. This is because the intensity changes. This is because the light transmittance of the laser beam apparently changes by 1 when the angle of incidence of the laser beam on the pellicle changes.

The second point is that the photoelectric detector is placed in a specific space, and depending on the adhesion position of the foreign object, that is, the scanning position of the spot light, the angle between the optical path of the scattered light reaching the photoelectric detector from the foreign object and the pellicle is determined. is to change. This is also a phenomenon caused by a change in the apparent light transmittance of the pellicle caused by a change in the incident angle of the scattered light with respect to the pellicle.

For this reason, a reticle without a pellicle and a reticle with a pellicle have different foreign object detection sensitivities even if the same amount of foreign matter is attached to the same position.

[Means for solving problems]

Therefore, in the present invention, the substrate to be inspected (reticle, mask, etc.)
The light transmittance or reflectance of a light transmitting substrate (pellicle or protective glass plate) provided almost parallel to the An input means for inputting the change characteristics, for example, a memory that stores information regarding the change characteristics of transmittance calculated in advance or experimentally determined, or a measuring section for actually measuring the change characteristics is provided. When laser light is incident on a reticle through a pellicle, or when scattered light from a foreign object is photoelectrically detected through a pellicle, information on the photoelectrically detected foreign object (electrical signal or numerical data on software) is collected. A correction means is provided for correction based on the change characteristics of transmittance.

[Effect]

With the above configuration, even if the angle of incidence of each lightning bolt (laser light or scattered light) on the pellicle changes when a laser beam or the like scans the reticle, the foreign object detection sensitivity will be adjusted by the hardware according to the change in the angle of incidence. This is corrected on the top or software, and it is possible to obtain uniform foreign object detection sensitivity over the entire inspection area.

When the laser beam is scanned in one dimension, this detection sensitivity correction can be applied to the photoelectric signal in real time according to the scanning position in the -dimension.

Therefore, by specifying only whether the reticle is equipped with a pellicle or not, it is possible to automatically inspect the presence or absence of foreign objects, the size of the foreign objects, and the state of adhesion with almost the same detection sensitivity for both. .

〔Example〕

FIG. 1 is a perspective view showing the principle of a measuring section of an input means used in a first embodiment of the present invention, 1, . 12 is a pellicle (thin film) 2 stretched on a pellicle frame 2;
Pellicle frame 2 with a straight line set perpendicular to a
can be rotated by a motor or the like using l as a rotation axis. A laser light source 1 outputs light of the same wavelength as the laser light used for foreign matter inspection, and the laser light is obliquely incident on the surface of the pellicle 2a including N, , 12, and the transmitted light is incident on the light receiving element 3. A straight line 12 is a projection of the optical axis of the laser beam from the light source 1 on the pellicle surface.

At this time, by rotating the pellicle 2a around ll and measuring the photoelectric output of the light receiving element 3 with respect to the incident angle, the dependence of the transmittance of the pellicle 2a on the laser beam on the incident angle (transmittance change characteristics) can be determined. be able to.

Furthermore, if the pellicle frame 2 and pellicle 2a are already attached to the reticle so that the pellicle 2a and the reticle surface are parallel, it is impossible to directly measure the transmittance, but the light reflected by the pellicle 2a is received. In this example, the pellicle 2a was rotated around the straight line II, but this rotation range is limited to the range of the incident laser beam in the foreign object inspection device and the pellicle. 2a or the angular range of the scattered light to the light receiving system, but this is not particularly necessary.

This is because it is possible to know the transmittance change characteristics of the pellicle 2a within a certain incident angle range for a light beam of a fixed wavelength.
Moreover, if the characteristics of the pellicle itself, such as whether it is made of a single material or whether an antireflection film is attached to the surface, can be determined, the characteristics can be sufficiently estimated. Note that depending on the rotation range of the pellicle 2a, it is necessary to move the light receiving element 4 for detecting reflected light in synchronization with the rotation of the pellicle 2a using a device not shown.

Further, the wavelength of the laser light from the laser light source 1 does not need to be the same as the laser light for foreign object inspection, and the transmittance can be estimated even if the wavelength is different.

Furthermore, the light source does not need to be monochromatic.

Further, in this embodiment, it is assumed that there is no thickness unevenness due to the position of the flange 2a, but even if there is thickness unevenness, it can be sufficiently dealt with by the method described later.

Also, the laser light reaching the pellicle 2a from the laser light source 1 has the same numerical aperture (N, A,) as the laser light on the foreign object inspection device side.
Although it is desirable that the spot size be the same, it is not necessary.

Now, FIG. 2 is a perspective view showing a structure according to a first embodiment of the present invention, in which the measuring section of FIG. 1 is incorporated into a foreign object inspection apparatus. A laser beam 100 emitted from a laser light source 11 is divided by a half prism 12 into a laser beam 101 directed toward a transmittance measurement section A, and a laser beam 102 directed toward a foreign matter inspection section B. The laser beam 102 heading toward the measuring section A is further divided into a laser beam 103 and a laser beam 104 by a half prism 13. The laser beam 104 is received by the light receiving element 14 for monitoring the amount of light. Further, the laser beam 103 is deflected by a mirror 15 and then enters a pellicle 2a installed at a predetermined position within the measurement section A. This pellicle frame 2 is a rotation axis set on the pellicle 2a! , in the direction of arrow 111 by an appropriate motor or the like. The reflected light 105 or the transmitted light 106 from the pellicle 2a is received by the light receiving element 4.3, respectively, and the amount of light received by the light receiving element 14 is taken as a denominator as a function of the incident angle (or exit angle) θ of the light beam. By taking each amount of light received by the element 3.4 into molecules, the change characteristics of transmittance or reflectance are actually measured. At this time, for example, when measuring the reflected light 105, it is better to move the light-receiving element 4 (rotate around the straight line 11) with the rotation of the frame 2a (frame 2), thereby reducing the size of the light-receiving surface of the light-receiving element 4. From that point of view, it is convenient. Incidentally, although the measuring section A in FIG. 2 does not include an optical system (lens, etc.), it goes without saying that an optimal system may be provided as appropriate.

Now, when the transmittance change characteristic of the pellicle 2a depending on the incident angle is measured in the transmittance measurement section A, the pellicle alone or the reticle with the pellicle is transported to the foreign matter inspection section B by a moving device (not shown). In this embodiment, the reticle 22 with a bevel
The following figure shows a case where a test is performed. In the foreign matter inspection section B, the optical path of the laser beam 101 is bent by a mirror 19 and reflected by a scanner mirror 20, thereby performing so-called laser beam deflection. A scanning laser beam is focused on a scanning locus 110 (shown on the surface of a reticle 220 in FIG. 2) by a scanning objective lens 21 and a beam expander optical system (not shown). At this time, the surfaces of the pellicle 23a and reticle 22 stretched over the frame 23 are located on the focal point, and if there is a foreign object there, scattered light will be generated from the foreign object, but this will be transmitted to the light receiving element via the condensing lens 24 and 26. 25.27
Detects foreign objects by receiving light. Various foreign object detection methods have been proposed, but the basic method is the method of Japanese Patent Application Laid-open No. 58-62 mentioned earlier.
As disclosed in Japanese Patent No. 544, the X-coordinate position of the scanning locus 110 of the laser beam (position in the laser scanning direction)
The change in the rate of absorption of scattered light into the light-receiving optical system due to By changing the comparator voltage (slice level) for binarization, changes in detection sensitivity depending on the location of foreign matter are made uniform.

Here, if the pellicle 23a is attached to the reticle 22, since the laser beam 101 is obliquely incident, the transmittance of the laser beam 101 at the pellicle 23a is 1.
Furthermore, if the incident beam optical system (lens 21, etc.) is not a so-called telescend link optical system, the incident angle changes due to laser beam scanning, so the transmittance will not be constant. In addition, even for scattered light from a foreign object, the angle between the rays of scattered light to the light receiving optical system (lenses 24 and 26) and the pellicle 23a changes depending on the scanning position of the laser beam.
The scattered light signal from the foreign object on the laser beam 2 changes depending on the presence or absence of a pellicle even if the laser beam is at the same scanning position.

Similarly, the intensity of scattered light from foreign matter adhering to the inner surface of the pellicle 23a changes depending on the scanning position of the laser beam. The change at this time can be estimated if the film thickness of the pellicle 23a is known, but since this information can be obtained by the transmittance measuring section A, it can be easily corrected when detecting a foreign object by scanning the laser beam. can.

Note that this correction does not need to be performed at the time of detecting a foreign object, and may be corrected by calculation on software when displaying the size, position, etc. of the foreign object as an inspection result after detection. In this case, the change characteristics of transmittance and reflectance can be measured after the foreign matter inspection.

In the foreign matter inspection, by moving the reticle 22 in the y direction, laser beam scanning is performed two-dimensionally, and the entire surface is inspected. In addition, foreign matter inspection of the reticle 22 or pellicle 23a is performed by moving the scanning locus 110 of the spot light of the laser beam onto the reticle surface or pellicle surface using a stage (not shown) that moves in the Z direction, and then moving it in the Y direction. Foreign matter inspection is performed on the reticle 22 and pellicle 23a, respectively.

Now, FIG. 3 is a block diagram of the electrical signal processing of the embodiment shown in FIG. 2. First, a photoelectric signal 30 from the light receiving element 14 is transmitted to a preprocessing circuit 3 including a voltage converter, an A/D converter, etc.
3 to the CPU 35. On the other hand, the light receiving element 3
．． 4, a photoelectric signal 31 from a light receiving element 4 that receives reflected light 105 is input to a CPU (calculator) 35 via a preprocessing circuit 34 including a voltage converter, an A/D converter, and the like. At the same time, data 32 is the angle of the rotation 111 of the pellicle 2a.
is also input to the CPU 35 from a rotary encoder (not shown) or the like. These data are sent to the CPU 35 only in the angular range necessary to know the incident angle dependence of the transmittance of the pellicle 2a.
After inputting the data, the CPU 35 creates a table of the relationship between the incident angle of the laser beam 1030 and the transmittance (transmittance change characteristics).

Further, the CPU 35 executes X based on the created table.
An operation is also performed in which the transmittance corresponding to the change in the scanning position of the laser beam in the direction is calculated and stored in the RAMs 36 and 57 on the signal side from each light receiving element 25 and 27. Therefore, each of the RAMs 36 and 57 has a trigger generator 3.
When the value obtained by counting the time series signals (pulse signals) from 8 is applied as an address, the transmittance at that scanning position is automatically read out.

In addition, the above preprocessing circuits 33, 34, CPU 35, RAM 3
6.57 constitutes the input means of the present invention, and the multiplier 43.44 and the multiplier 49.50 constitute the correction means of the present invention. Also, pre-processing circuits 33, 34, C
PU35 and RAM36.57 are parts that hold information regarding the light-transmissive substrate (pellicle) in the present invention, so
This is particularly referred to as the pellicle information holding section 37.

Incidentally, the scattered light from the foreign object is received by the light receiving elements 25 and 27, and photoelectric signals 45 and 4 of a magnitude corresponding to the amount of light are generated.
6 is obtained. These signals 45 and 46 are converted into voltages by voltage converters 47 and 48, respectively. Here, regarding the scanning position of the laser beam in the
This can be determined by counting the time-series signal (pulse signal depending on the position) from the trigger generator 38. Then, based on this count value, the scanning position in the X direction when the scattered light is emitted can be determined.

Even if there is no pellicle, the amount of scattered light incident on the light receiving element 25.27 changes depending on the position of the solid angle of reception in the X direction, so voltage converters 47.27 are used to normalize the amount of light.
Variable multipliers 49 and 50 are provided, respectively, for performing gain adjustment on the signals from each of 48. The enhancement degree conversion constant for this purpose is determined in advance through experiments, etc., and is stored in ROM42 and 41.
In response to the time-series signal from the trigger generator 38, the intensification degree conversion values are sequentially read out from the ROM 42.41, and the respective multipliers are multiplied by the intensification degree variable device 49 via calculators 44 and 43. and 50. As a result, the photoelectric signal correction of the amount of scattered light is performed according to the scanning position in the X direction.The other input constant of each of the multipliers 44 and 43 is is set to 1 if R
The value from OM42.41 is used as is for the variable amplification variable 49.
50 is instructed. Here, if the pellicle 23 is attached, it is necessary to further change the correction value according to the scanning position in the X direction. In other words, if the position of the foreign object in the X direction is known, first the incident angle of the laser beam that is incident on the foreign object can be determined. In addition, the scattered light from the foreign object also enters the light receiving element 25.27 as a certain light ray bundle, and the angle of incidence between the light ray bundle and the pellicle 23a at this time can be easily determined from the geometrical arrangement of the light receiving element 25.27. Desired. Therefore, the scanning trajectory 11
The time-series signal from the trigger generator 38 corresponding to the X-direction position of the spot light on Then, it is possible to sequentially obtain the scattered light transmission amount correction value according to the scanning position of the laser beam in the X direction. The correction value corresponding to the scanning position in the X direction of the laser beam (spot light) caused by the presence of the pellicle is the same as the correction value in the ROMs 42 and 41, so it is easy to multiply the two correction values. 44.43, and then add the multiplication factor to 49.50.
If the intensity conversion value is input when there is a pellicle 23a, the amount of scattered light can be correctly normalized even if there is a pellicle 23a. The variable multiplier 49 standardized in this way.
Each signal from 50 has a reference voltage (slice level) 53
．． Comparators 51 and 52 compared with 54 perform binarization on the amount of scattered light above a certain signal level. By using an AND circuit 55 that outputs a digital signal 56 when both amounts of scattered light are above a certain level, for example, scattered light from a reticle pattern edge that emits strongly scattered light in a specific direction can be prevented from being erroneously detected. , it is possible to know the presence of foreign objects that generate scattered light.

In the above, the scattered light from the foreign object is transmitted to the pellicle 23 as a beam of light.
The fact that the scattered light has polarization properties (differences in foreign object detection sensitivity depending on the polarization component), etc., must be determined in advance by the CP.
It is clear that the correction will be more accurate if various physical conditions are included in U35.

Note that the correction means using the pellicle does not need to be exactly the same as in this embodiment; for example, it may be configured to make the reference voltages 53-54 variable based on information from the pellicle information holding section 37. Alternatively, after inspecting a foreign object, the transmittance may be measured by the transmittance measuring section A, and the display level may be varied when displaying information on the size and position of the foreign object on the CRT after detecting the foreign object. For this display method, for example, PROCEEDINGS OF 5PIEVo
1.470 (March 14.15, 1984) 242
-! - What is described on page 249 can be applied. In this case, the software calculation corresponds to the correction means of the present invention. Furthermore, if the transmittance change characteristics of the pellicle are known in advance, there is no need to use the measuring section A.
It is clear that it may be entered in '5.

Furthermore, the transmittance data input to the CPU 35 is stored in the RAM 57.
．． 36, some assumed data is stored in the CPU 35, data that closely corresponds to the data obtained by the transmittance measurement section A is selected, and the transmittance (corrected factor) and convert it to RAM57
．． A method of outputting to 36 may also be used. In this case, CPU35
, various data stored in the RAM 36.57 are determined, for example, as shown in the graph shown in FIG. The CPU 35 stores some of the reflectance change characteristics (incidence angle dependence) that are predetermined depending on the type of beam. Here, it is assumed that two change characteristics typically shown in FIGS. 4(a) and 4(b) are stored as a database. In FIGS. 4(a) and 4(b), the horizontal axis represents the angle θ (d e g) between the beam and the incident light beam, and the vertical axis represents the reflectance. Now, the change characteristics of the reflectance in the angle range of 20° to 40° measured by the light receiving element 4 in the measuring section A are tentatively determined by the CPU 35 as the characteristic A shown in FIG. 4(a).
If it is determined that the CPU 35 is similar to
The data of the correction curves A-1 and A-2 shown in c) and (d) are output to the RAM 36.57, respectively. Figure 4 (C),
In (d), the horizontal axis is the scanning trajectory 1 of the laser beam spot light.
10, and the vertical axis represents the gain adjustment amount given to the multipliers 43 and 44 (ie, the multipliers 49 and 50). In Fig. 4 (C) and (d), the correction curve A
A gain determined by −1 is given, for example, to the photoelectric signal 45 from the light receiving element 25, and at the scan start point x8, almost no correction is performed (gain 1), and at the scan end point Xr, the degree of enhancement is approximately doubled. It will be done. On the other hand, the gain determined by the correction curve A-2 is given to the photoelectric signal 46 from the light-receiving element 27, and is adjusted almost continuously so that it is approximately twice as much at the starting point Xi and approximately three times as much at the end point x. be done. Further, if the CPU 35 determines that the actually measured reflectance change characteristics are similar to that shown in FIG. 4(b), the CPU 35
) The data of correction curves B-1 and B-2 shown in R
Output on AM36.57.

If the above database of reflectance (or transmittance) change characteristics or curve characteristics for gain correction can be further subdivided and prepared in advance for many types of characteristics, fine-grained information can be obtained regardless of the pellicle material, dimensions, etc. Needless to say, sensitivity can be corrected.

FIG. 5 shows a second embodiment of measuring the incident angle dependence of the transmittance of a pellicle.
The reflectance is measured here. The laser beam 103 passes through the mirror 15 in FIG.
Instead, it enters the scanner mirror 62. The scanner mirror 62 rotates and oscillates in the direction of an arrow 63, and the laser beam 103 is deflected within a range sandwiched between the laser beams 64 and 65. This laser beam 6
4 and the laser beam 65 are refracted by the condenser lens 60, and these laser beams 64 or 65 whose optical axes intersect at point P of the pellicle 23a on the pellicle frame 23 attached to the reticle 22 are also refracted as shown in FIG. It is assumed that the light beam has a predetermined numerical aperture and is focused as a spot light onto the pellicle 23a, as in the case of FIG.

The laser beam 64 is incident on the pellicle 23a at an angle θ, and the specularly reflected light is also reflected from the pellicle 23a at an angle θ1. Similarly, the laser beam 65 is incident on the pellicle 23a at an angle of θ2 (θ2>θ,), and the specularly reflected light is also specularly reflected at an angle of θ2. These specularly reflected lights are again collected on the light receiving element 4 by the condensing lens 61.

Here, since the angle of rotational vibration of the scanner mirror 62 corresponds to the incident angle of incidence on the pellicle 23a, the angle information detected by the encoder etc. of the scanner mirror 62 and the photoelectric signal from the light receiving element 4 are Based on , the transmittance of the pellicle 23a (
The incident angle dependence (change characteristics) of reflectance) can be estimated. This second embodiment has the feature that the dependence of the transmittance on the angle of incidence can be measured without rotating the pellicle frame 23 or moving the light receiving element.

As described above, in each of the embodiments of the present invention, it is assumed that the thickness of the pellicle is uniform throughout the scanning position, and the actual measurement of the transmittance change characteristics in measurement section A was also performed at one point on the pellicle. However, if there is thickness unevenness depending on the position on the pellicle, this will also cause a change in transmittance. For this reason, the first
It is preferable to horizontally move the pellicle along the straight line 11 or 12 shown in the figure and perform similar actual measurements at different positions. In this case, if there is thickness unevenness in the scanning direction of the laser beam in the foreign matter inspection section B, the data is input to the CPU 35 of the pellicle information holding section 37 in FIG. It may be corrected by .50.

If there is thickness unevenness in the y-direction perpendicular to the scanning direction of the laser beam, the variable intensification changer 49.
It is only necessary to adjust the gain of 50.

Furthermore, in each of the embodiments, the laser beam of the foreign object inspection section B was assumed to be incident on the reticle 22 from the pellicle 23a side. The present invention can be implemented in the same manner even in the case of photoelectric detection. Furthermore, reticle 22
The same applies to the case where the pellicles 23a are stretched in parallel at predetermined intervals on both sides.

Alternatively, the foreign matter inspection section B and the measurement section A shown in FIG. 2 may be configured as one unit. In this case, scanner mirror 2
0 so that the spot light can temporarily stop at the center of scanning, and the light receiving element 4 is placed at the position where the specularly reflected light reaches, the change characteristics of the transmittance of the pellicle can be determined in the same way. Furthermore, in the measurement part A, the laser beam incident on the pellicle does not necessarily have to change the incident angle continuously; if the actual measurement is made for at least two different incident angles, The case can be determined by calculation.

In each of the embodiments of the present invention, a dustproof pellicle is provided at a predetermined interval from the reticle surface. The present invention can be similarly applied to a reticle having a structure in which a dustproof glass plate is integrally bonded to the surface.

Further, although the adjustment (correction) of the foreign object detection sensitivity in each embodiment was performed after photoelectrically detecting the scattered light, for example, in the laser optical path between the half prism 12 and the mirror 19 in FIG. Optical m adjuster (attenuator) such as AOM
, some correction factors can be similarly achieved by rapidly modulating the intensity of the laser spot light scanning the reticle surface (or pellicle surface) by a predetermined amount corresponding to the scanning position. Foreign object detection sensitivity can be adjusted.

As in each embodiment, when the laser beam is obliquely incident on the reticle surface and multiple light receiving elements are looking at the scanning locus on the reticle surface at different spatial positions, it is not enough to adjust only the intensity of the laser spot light. It is difficult to completely correct sensitivity unevenness due to changes in the transmittance of the pellicle.

However, if the intensity of the spot light can be modulated according to the scanning position, the amount of correction given to the electrical system on the light receiving system side (variable intensification variable device 49.50, etc.) can be small, and as a result, foreign particles The effect is that the overall dynamic range of detection can be expanded. This means that it is possible to detect foreign substances from small to large with appropriate sensitivity. Note that even when the laser beam is obliquely incident, the same correction can be made by simply modulating the intensity of the spot light depending on the arrangement of the light receiving elements.

〔Effect of the invention〕

As described above, according to the present invention, even when a dustproof transparent substrate (thin film, glass, plate) is provided on a mask, reticle, etc., sensitivity unevenness occurs over the entire surface of the inspection area that is relatively scanned by the light beam. Therefore, accurate defect inspection can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the basic structure of a transmittance measuring section according to a first embodiment of the present invention, and FIG. 2 is a perspective view showing the structure of a defect inspection device according to a first embodiment of the present invention. FIG. 5 is a graph showing the correction characteristics of the power, and FIG. 5 is a diagram showing the principle structure of the second embodiment of the transmittance (reflectance) measuring section. (Explanation of symbols of main parts) ■, 11...Laser light source 2.23...Pellicle frame 2a, 23a...Pellicle (thin film) 22...Reticle 3.4.25.27...Light reception Element 20... Scanner mirror 37... Pellicle information holding section 43.44... Multiplier 49.50... Width variable variable device

Claims (5)

[Claims] (1) A light-transmissive substrate is provided approximately parallel to the substrate to be inspected, and a defective portion existing on the surface of the substrate to be inspected or the light-transmissive substrate is relatively scanned with a light beam, and the characteristic occurring at the defective portion is scanned with a light beam. In an apparatus for detecting the defective portion by photoelectrically detecting optical information of the light transmitting substrate, means for inputting substrate information corresponding to the light transmittance or reflectance of the light transmitting substrate; When optical information is incident on the board to be inspected through the substrate or is photoelectrically detected from the defective part through the light-transmissive substrate, the information about the defective part obtained by the photoelectric detection is used as the board information. What is claimed is: 1. A defect inspection device comprising: a correction means for correcting based on the corrected information. (2) scanning means for scanning the light beam at an oblique incidence on the substrate to be inspected in at least one dimension; 2. The apparatus according to claim 1, further comprising a memory circuit that stores information on a change in light transmittance of the light-transmitting substrate in correspondence with the scanning position. (3) The substrate information input means includes a measurement unit that actually measures information regarding the light transmittance or extinction ratio of the light transmitting substrate in accordance with the incident angle of the light beam. The device according to scope 1. (4) The correction means includes an adjustment circuit that electrically varies the detection sensitivity in accordance with the board information when detecting the defective portion based on the magnitude of the photoelectrically detected signal. A device according to claim 2 or 3, characterized in that: (5) The correction means may apply the correction by calculation to the information of the defective part obtained within the predetermined region after the inspection with the light beam is completed for the predetermined region on the substrate to be inspected. A device according to claim 2 or 3, characterized in that: