JPS5862544A - Device for checking foreign matter - Google Patents

Abstract

PURPOSE:To detect whether foreign matters are adhered on the obverse side of a substance to be checked or on the reverse side thereof by a device wherein the scattered lights are photoelectrically detected on both sides of the checked substance to check the presence of foreign matters based on the difference between both the detected photoelectric signals. CONSTITUTION:Photoelectric signals detected by a photoreceiving unit A become almost same in their levels for foreign matters (i) and (j). But a partial scattered light 1b generated from the foreign matter (i) reaches a photoreceiving unit B after passing through a glass plate 5a. The intensity of the scattered light 1b is generally smaller than that of a scattered light 1b, but photoelectric signals in some degree are generated in both photoreceiving units A and B due to attachment of the foreign matter (i). Meanwhile, the scattered light from the foreign matter (j) attached onto a shielding portion 5b will not reach the photoreceiving unit B. Thus, by measuring the photoelectric signals from both photoreceiving units A and B, it can be judged whether the foreign matter is adhered on the transparent portion or on the shielding portion.

Description

[Detailed Description of the Invention] □ The present invention relates to a device for detecting abnormalities such as minute dust. Regarding.

In the process of manufacturing photomasks for L81, foreign matter may adhere to the reticle, mask, etc.60
．． These substances cause defects in manufactured masks and wafers.

On the other hand, defects in reduction projection type baton printing appear in the equipment as defects in all parts of each mask and wafer, so strict inspection is required during the manufacturing process. For this reason, it is generally considered appropriate to carry out a visual inspection for foreign substances, but this method usually takes many hours to carry out the inspection, resulting in operator fatigue and a reduction in the calibration rate.

Therefore, in recent years, various devices have been developed that automatically detect foreign particles attached to a mask or reticle by irradiating them with a laser beam or the like.

For example, a mask or reticle is irradiated with a laser beam, and the original spot is scanned two-dimensionally. At this time,
Scattered light from pattern edges (edges of light-shielding parts such as chrome) on the mask defect has strong directivity, while scattered light from foreign objects occurs non-directionally. Therefore, an apparatus is known that performs photoelectric detection to discriminate these square scattered lights and inspects whether foreign matter is attached to the mask or reticle from the scanning position of the light spot. However, since this device scans the entire surface of the mask or reticle with the original spot, there is an additional problem that the smaller the diameter of the original spot in order to accurately detect small particles, the longer the inspection time. Then, whether the foreign matter is attached to the light-shielding part such as chrome or the glass surface (light-transmitting part), and even if it is attached to the light-transmitting part, is it covered? It is difficult to inspect the state of adhesion of foreign matter, such as distinguishing whether it is attached to the surface of the object to be inspected on which the laser beam enters or whether it is attached to the back surface.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a foreign matter inspection device that can detect foreign matter adhering to an object to be inspected at high speed, and can quickly inspect the state of adhesion of foreign matter.

The foreign matter inspection device of the present invention that achieves this purpose has the following configuration. That is, the apparatus of the present invention is an apparatus that scans one surface of a light-transmitting object to be inspected with an original beam and inspects the presence or absence of attached 14-chip based on optical information generated from the object to be inspected. Looking at the one side,
A first photoelectric means arranged to receive scattered light emitted from one side; 9. To receive scattered light. Compare the signals of both the means of mourning@2 means 〒-2 and;
and a detection device that generates a detection signal in accordance with the state of adhesion of foreign matter. , .

Before explaining the present invention in detail, let us explain how the light scatters and scatters when the original beam is irradiated onto the food, depending on the state of adhesion of foreign matter. This will be explained with reference to Figure 1.2.3. Here, it is assumed that the light beam illuminates the object to be inspected at oblique incidence. The scattering of these items ″−&″. j'', etc. '1') This is to improve separation from the number 7 scattered light from the light shielding part.

Figure 1 shows a pattern of an ask and a reticle (hereinafter collectively referred to as a mask) drawn as an object to be inspected.
A round surface is irradiated with laser light as the original beam, and the scattering of the laser light by the 14 proboscis attached to the glass plate of Photomass 2 and the scattering by foreign matter attached to the light shielding part are shown. It is. FIG. 2 shows the state of scattering due to foreign matter adhering to the glass plate and the scattering due to the edge portion of the light shielding portion.

-Figure 3 shows the state of scattering due to foreign matter adhering to the front and back surfaces of the transparent part of the glass plate.
1. 3 In Fig. 1, the glass and glass IES of photomask S
Surface SI (
□Hereinafter, this surface will be referred to as pattern surface Si. ), the laser beam 1 is incident normally through the glass plate 5a or the east layer light plate 5b. *, 05 in the figure, one beam of light other than laser beam 1 causes only scattering, dispersion, and distortion. In FIG. 1, a light receiving section (4
) reflects the specularly reflected light. I'm Kll.

However, in reality, it is placed at a position where specularly reflected laser light does not enter. The 1+ light receiving section (4) is arranged so as to obliquely look into the area irradiated with the laser beam 1. This is glass plate S
This is to prevent as much as possible from receiving scattered light caused by fine irregularities on the pattern surface 8° of the light shielding portion 5b and the surface of the light shielding portion 5b. Further, on the surface 81 (hereinafter referred to as the back surface) opposite to the pattern surface S of the glass plate 51, a light receiving WA (B) including a condenser lens and a photoelectric element tube is provided. This light receiving part (B) is arranged in a plane symmetrical relationship with the light receiving part (4) with respect to the glass plate Sa (patterned surface 8.), and the laser beam 1 is directed from the back 1j S The irradiated area is viewed diagonally. In Figure 1, the light receiving part (B)
Although it is shown to receive the laser light that directly passes through the glass plate 5a, in reality, it is provided at a position that does not receive the laser light that directly passes through the glass plate 5a. In other words, the light receiving section (
4), (In is the scattering f non-directionally generated from foreign matter)
t, is placed at a position where it receives light.

Therefore, as shown in the figure, the difference between the scattered light generated by the foreign matter i attached to the transparent portion of the ratchet plate 5a and the foreign matter j attached to the portion 11'yt, 5b will be explained.

The magnitude of the photoelectric signal detected by the light receiving part (A)K is
Foreign matter 1 and J are almost the same. It is foreign matter 1%'J
This is because when the laser beam 1 is irradiated on the foreign matter i1 and the foreign matter i1 and j have the same size, the intensity of the non-directionally generated scattered light 1a will also be the same. However, some of the scattered light 1b generated by the amount of foreign matter passes through the glass plate 5a and reaches the light receiving section (B). Generally, the scattered light 1b is the scattered light 1a
Although the light receiving portions (A) and (B) are smaller than those shown in FIG. Of course, the scattered light from the foreign matter j adhering to the line light 11SbK does not reach the light receiving part (1).

Then, by examining the photoelectric signals of the received light 5cA) and CB), it was determined whether the foreign matter had adhered to the transparent part of the □ glass plate 5m, or whether it had adhered to the 11th part 5b. a. □□, Old 9°, “et!.

By the way, at the edge portion of the jl light section 5b, reflected light with strong bending directionality and scattered light with non-directionality are generated. Therefore, even if the light receivers S((transfer) and (I9) are arranged so as to avoid the highly directional reflected light from the edge portion and receive only the scattered light, it is difficult to determine whether the scattered light is due to foreign matter or not. The principle of this will be explained based on FIG. 2. In FIG. 2, the light receiving section that receives the scattered light is arranged in the same way as in FIG. 1.

The obliquely incident laser beam 1 is specularly reflected by the pattern surface S of the photomask 5, but is scattered by the foreign matter i or the edge portion of the light shielding portion 5b as a circuit pattern. (Specular reflection light etc. are omitted.) The M base portion 5b has a layer thickness of 0. I
The light densely layered on the pattern tlioSl at about J1m, the same scattering ft, lc directly outside the glass plate 5a.
The intensity of the scattered light 1d and the scattered light 1d traveling toward the inside of the glass plate 5a are almost equal. After the scattered light 1d passes through the inside of the glass plate 5a, the 'IIk plane B! Go outside more. On the other hand, the size of the foreign object is several μm or more, and the light scattered by the foreign object vBl is the scattered light 1, which travels toward the rounded shape where the foreign object i is higher than the rod surface Sl. The scattered light 1f traveling to the amount of foreign matter is also weak. This tendency becomes stronger as the difference in the magnitude of the electric signal increases with respect to the pattern image 81 at the light receiving section (4).

This phenomenon occurs in plane 8. The scattering originally behaves as an llI plane wave with respect to the light shielding part SbK that is in close contact with the surface, but since the foreign object i is partially in the upper surface, it scatters in free space, and the scattered light is incident on the pattern EIi81 at a grazing angle. Then, the reflectance increases and the pattern surface 8. This can also be explained by the fact that the proportion that goes inside is smaller. Therefore, pattern surface 8. At the same time, the scattered light is detected by the light receiving IB (A), and the back side 8
The nine scattered particles that passed through the center are also detected by the light receiving unit 1ff(B)K, and it is determined whether the ratio of the amount of light between the two is, for example, twice or more. It is possible to determine whether the

Next, the principle of discriminating foreign matter adhering to the front and back sides of the glass plate 5a will be explained using Figure 3. In this figure, the light-receiving parts (A) and (B) are provided diagonally backward from the part on the photomask that is irradiated with the laser beam 1, that is, on the incident side of the laser beam 1. Receives scattered light.

Here, the laser beam 1 is applied to the surface of the photomask 5 on which no pattern is formed, that is, the back surface 8. When the laser beam is incident on the back rjjIS1, the laser beam is scattered by the foreign matter k attached to the back side rjjIS1, and the pattern surface 8. on the side where the pattern is formed.
It shows the difference in scattering depending on the amount of foreign matter attached to the surface.

Laser '#, 1 is on the back side 8. On the other hand, the light is incident obliquely, part of it is reflected, and part of it is transmitted, reaching the pattern surface S1. foreign object k
The light scattered by j'e1g is photoelectrically converted by the light receiving part (N). Among the light scattered by the foreign matter i that adheres to the transparent part of the pattern surface S1, it passes through the inside of the glass plate 5a and is reflected on the back surface 8. Therefore, the scattered light 1h appearing on the laser beam incident surface is photoelectrically converted by the light receiving section (A).

By the way, among the scattered light by the foreign object 1, the scattered light 1h and the pattern surface 8. Scatter that does not enter the inside of the glass plate Sm! When compared with Il, the scattered light 1h suffers reflection loss due to the pattern surface 81 and the back surface 8, so its intensity is weaker than that of the scattered light 11. The intensity ratio of these two is the light receiving part (4)
, CB), if the receiving direction of the scattered light is made to be close to the back m 8 m or the pattern surface Bl, the light intensity tends to be large. This is based on the fact that the greater the angle of incidence of light, the greater the reflectance on the large S surface. Therefore, by monitoring the outputs of the light receiving sections (A) and (B) while changing the incident position of the laser beam 1 on the photomask 5, signals as shown in FIGS. 4(M) and 4(b) are obtained, respectively. Therefore, the vertical axes in Figure 4 (a) and (b) are the light receiving area (A's).
, as) is proportional to the intensity of the received scattered light, and the horizontal axis represents time or the position of the laser spot with respect to the photomask 5. 141w1! In the scattering of laser light by lk, the signal waveform AI, 81 in FIG.
When comparing the signal magnitudes FAI and PH1, FAI is about 3 to 8 times larger than FBI,
In the scattering by foreign object 1, signal waveforms such as A2 and B2 are obtained, and when comparing the sizes PA2 and pBZ, PH
1 is about 3 to 8 times larger than PA2. Therefore, when the scattered light exceeds a certain level, the light receiving portion 5 of the light receiving portion (4)
If the output ratio to (B) is twice, for example twice,
It can be determined that the foreign matter is attached to the back surface S of the laser beam incident axis.

Next, embodiments of the present invention will be described based on the drawings.

FIG. 5 is a perspective view showing a first embodiment of the foreign matter inspection device, and FIG. 6 is a circuit diagram showing a detection circuit suitable for the configuration shown in FIG.

This embodiment is suitable for inspecting unpatterned plain glass or a mask with a relatively simple pattern rather than a photomask with a complicated pattern. A photomask 5 as an object to be inspected is placed on the stage (2) with only its peripheral portion supported. The mounting table can be moved one-dimensionally as indicated by an arrow 4 in the figure using a motor 6, a feed screw, and the like. Here, the pattern surface of the photomask 5 is
Define as a plane. The amount of movement of this mounting table (2) is fixed by a length measuring device T such as a linear encoder. On the other hand, the laser beam 1 from the laser light source is appropriately transmitted to the expander (
(not shown) and an optical member such as a condensing lens 3, the beam is converted into an arbitrary beam 11 to increase the light intensity per unit area. This laser beam 1 is transmitted through a vibrator, a galvanometer mirror, etc.
An area 11L in the X direction on the photomask s is scanned by a scanner 2 having a vibrating mirror such as the one shown in FIG. At this time, the scanning laser beam 1 is applied to the surface of the photomask 5 (x-ysFJ
li) Against K? , N, and t are obliquely incident at an incident angle of 70" to 80 degrees. Therefore, the irradiated portion of the laser beam 1 on the photomask s becomes a circular spot extending in the y direction in the figure. Therefore, the area where the photomask 5 is scanned by the laser beam 1 by the scanner 2 becomes a band-shaped area with a range in the X direction and a predetermined spread in the y direction.Actually, the laser beam 1 scans the photomask 5. In order to scan the entire surface, the aforementioned motor 6 is also driven at the same time and moves in the photomask Sky direction at a speed lower than the scanning speed of the laser beam 1. At this time, the sub-length device T moves the photomask 5 of the laser beam 1. Output a measurement value related to the irradiation position in the y direction above.

In addition, original information from nine foreign substances attached to the photomask 5,
That is, light receiving elements 11 and 13 are provided to detect scattered light that occurs non-directionally. Among these light receiving elements, the element 11 corresponds to the light receiving part (A), and the scattered light generated from the front side of the photomask 50 irradiated with the laser beam 1:
.

The book is placed so that it receives light. -10,000, the light receiving element 13 is
It corresponds to the light receiving section (B) and is arranged to receive scattered light generated from the back side.

Furthermore, a lens 10 is provided on each light receiving surface of the light receiving elements 11 and 13.
, 12, the scattered light is collected. and lens 10
The optical axis is set so as to be oblique with respect to the x-y plane, so that approximately the center of the scanning range of the laser beam 1 is viewed from the front side of the photomask 5. On the other hand, the optical axis of the lens 120 is set to be symmetrical with the optical axis of the lens 100 with respect to the x-1 plane. In addition, the respective axes of the lenses 10 and 120 are arranged obliquely with respect to the direction of the prosthetic hand within the scanning range.
That is, it is determined to form a small angle with respect to the xz plane.

In FIG. 6, the valley means signals of the light receiving elements 11 and 13 are as follows:
The signals are input to amplifiers 100 and 101, respectively. The amplified photoelectric signal sI) is then input to each of the two comparators 103 and 104.The amplified photoelectric signal e is then input to the other input of the comparator 104 via the amplifier 102 at the amplification degree. is applied to t#J, when the amounts of light received by the light receiving elements 11 and 13 are equal, the signals @1, . . . both have the same magnitude. Furthermore, the slice voltage Vs from the slice level generator 106 is applied to the other input of the comparator 103.

And each output of the comparators 103 and 104 is connected to the AND circuit 10.
5. This slice level generator 106 changes the magnitude of the slice voltage Vj in synchronization with the scanning signal SC for vibrating the scanner 2. This is laser beam 1
This is because the scanning changes the distance from the light receiving element 1177 to the irradiation position 1t of the laser beam 1, that is, the solid angle at which the lens 10 receives the scattered light changes. Therefore, in synchronization with scanning, the slice voltage vS is configured to be varied according to the irradiation position of the laser f,1.

In this configuration, the amplification factor of the amplifier 102 is /Ii, 1
．． It is set in the range of 5 to 2.5, for example 2. This is because the ratio of the magnitude of the scattered light generated on the incident side and the magnitude of the scattered light transmitted through the photomask 5 among the scattered light generated from foreign matter attached to the incident side of the laser beam 10 is shown in Figures 3 and 4. This is because, as explained above, it will more than double.

In addition, the comparator 103 outputs the logical value I'll only when the signal e1 is greater than the slice voltage vS. Also,
Comparison device 104 compares signal e1 and signal .
Compare y and .

It outputs a logical value of "1" only when . . , >K. Therefore, AND circuit 105 generates a logic value "1" only when the outputs of comparators 103 and 104 are both logic value "1".

Next, the function and operation of this embodiment will be explained.

First, if a J14 object is attached to the surface on the incident side of the laser beam 1, and if the laser beam 1 irradiates only that foreign object, the signal will become larger than the slice voltage vS, so compare! 1
03 outputs the logical value 1-IJ. Also, at this time...
1>K., and the comparator 104 also outputs the logical value 11. Therefore, the AND circuit 105 generates the logical value 11''.

Next, if foreign matter is attached to the back side, the laser ′yf, 1
Since r and i are obliquely incident on the photomask 5, most of the light is specularly reflected by the glass surface of the photomask 5, and a portion of the light irradiates the foreign matter on the back surface. Therefore, among the scattered light from foreign objects,
'The scattered light reaching the light receiving element 11 has a smaller value than the scattered light reaching the light receiving element 13, that is, taX.

The comparator 104 outputs a logical value rOJ. Therefore, at this time...) Vs holds true, no, -C
, Aji once □. 5□, □10" is generated. Mae, i1
When scattered light □ is generated from the edge of the unitary part, the amount of light received by the light receiving elements 11 and 13 is approximately equal to the amount of light received by the light receiving elements 11 and 13, as shown in FIG. Therefore, the comparator 104 outputs the logical value "0". Therefore, the AND circuit 105 generates a logic value of 10.

The magnitude of the slicing voltage Vs is related to the foreign object detection ability, and the smaller the slitting voltage Vj is, the smaller the foreign object can be detected.

In this manner, when foreign matter is attached to the front side (laser light incident side) of the photomask 50, the AND circuit 105 outputs a logic value of "1" as the inspection result.

As described above, this embodiment has an extremely simple configuration when scattering by VC such as circuit patterns is high and only large foreign matter is required to be shipped. It is equipped with the feature t- that allows for high-speed inspection by distinguishing whether the

The above is a description of the case where laser light is incident from the side on which a circuit pattern is formed and foreign matter attached to the incident surface is detected.1.By the way, the reticle used in a reduction projection exposure apparatus With the mask, not only the foreign matter attached to the circuit pattern side but also the foreign matter attached to the back surface without a pattern is transferred. The minimum size that can be transferred with an attached foreign substance is approximately L5 times the length and approximately twice the area ratio of the minimum size that can be transferred with a foreign substance attached to the surface on which the circuit pattern is placed. It is also necessary to detect attached foreign matter with the required sensitivity.K for detecting foreign matter on the back side is explained in the first embodiment, and may be used in a companion device with the photomask turned upside down. However, even with this method, the following problem occurs with a photomask having a complicated pattern. Namely, due to the relationship between the detected intensity of light scattered by a foreign object on the side without a circuit pattern and the size of the foreign object, When trying to judge the size of a foreign object, the relationship between the detected intensity of light scattered by a foreign object on the side facing the circuit pattern and the size of the object will be different, which may lead to errors in determining the size of the foreign object. Naru□.

Not only that, but the detection of foreign matter itself becomes difficult due to the influence of scattered light from the edges of the light-shielding portions of the pattern.
□ Seventh embodiment of the stripe 2 of the present invention will now be described based on FIGS. 7 to 9. Figure 7 shows the second embodiment of the item inspection device 1I.
A perspective view □ of IAiPI is shown, and the difference from the first embodiment is that one more set of light receiving sections is provided.

FIG. 8 is a diagram showing the state of the output of each light receiving element due to scattered light from a foreign object. Further, FIG. 9 is a series diagram of a detection circuit suitable for this second embodiment. : ゛In Fig. 7, descriptions of those having the same configuration and function as those in the embodiment of stripes 1 will be omitted. In this second embodiment, a light receiving system having an equal light receiving solid angle is further provided on the incident side of the laser ft1 of the photomask S and on the opposite side thereof. As shown in the figure, there is a condenser lens 2o and a light receiving element 21 that obliquely look at the front side of the photomask 5 (laser incidence 11), and a light condenser that obliquely look at the back side of the photomask 5. It is composed of a lens 22 and a light receiving element 23. Of course, each optical axis of the lenses 20 and 22 has a scanning range l! It faces almost the center of L.

Furthermore, each optical axis is determined to coincide with II (a plane parallel to the xz plane of the xys coordinate system) that intersects the longitudinal direction X of the scanning range sL.

Further, at this time, the angle ti30 to ti4 formed by the optical axes of the lens 20 and the lens 10 is determined at the front and back of the garden. The same applies to the angle formed by the optical axes of the lens 22 and the lens 12.

Therefore, in this embodiment, in addition to utilizing the fact that the directivity of the scattered light due to the foreign matter and the circuit pattern is different with respect to the origin of the light traveling to the front side of the photomask S, the directionality of the scattered light due to the foreign matter and the circuit pattern is also used. The difference in intensity ratio is also used to inspect foreign substances.

FIG. 5 is a perspective view of this embodiment, showing the moving stage 12 on which the object 6 is set, and the motor T that drives the movement of the moving stage 12.
3, and an encoder 7 that performs position detection in the direction of arrow 8.
4 is also displayed in a bag.

Fig. 8 (1), (b), ((+), (d) shows the light receiving element 2
The magnitude of the photoelectric signal from 1.11.23.13 is plotted on the vertical axis, and time is plotted on the horizontal axis in common with #I8 (a) to (d). The spot of laser party 1 is photomasmo and the horizontal axis of 11 also corresponds to the spot position.

When the laser beam is incident on the circuit pattern and is scattered, the outputs from the photoelectric elements 21, 11, 23, 13 in FIG. 7 are 1 and BL in FIG. 8, respectively.

CI, Di, and their respective peak values are PAI
SPBIXPCI, PDI. In this case, the PAI is larger than the peak PBI as the photoelectric output of the ninth receiving elements 21 and 11, which affect the directionality of the scattered light.
Since the directionality is not perfect, the beak pill is zero. The output peak value, PCI, and PDI of the true light receiving element 23.13 of the photomask S are each FAI.

It has a value close to that of the FBI. This can be done in nine ways as explained in FIG. 2 above. However, if the laser beam is scattered by a foreign object, the output from each photodetector will be i
), A 2, B2, C2, D2, and the peak values are PA2, PH1, PO2, P, respectively.
It becomes D2. Because the directionality of scattered light is low, PA
The difference is small between 2 and PH1, but there is a large difference between PA2 and PO2, and between PH1 and PD20.
The ratio of PA2 and PH1 is about 8 times larger. For example, the smaller peak value PB of the scattered signals from the circuit pattern
As a level 8Li slice voltage □ smaller than I,
If each signal in FIGS. 8(a) and 8(b) is sliced to detect the threatening scattered light caused by a foreign object as small as possible, the circuit pattern up to 1 will also be determined as a foreign object. However, by calculating the ratio of the outputs of the light receiving element 21 and the light receiving element 23 in Fig. 7, and the ratio of the outputs of the light receiving element 11 and the light receiving element 13 in Fig. 7, the signal in Fig. 8 (m) exceeds 8L. If (b) (!1' also exceeds SL, then ζ and if this ratio exceeds a certain level, for example, 2 times or more, it is determined that it is a foreign object), then using the low level 8L as above?
Only foreign objects can be detected correctly. Figure 9 is a block diagram of the signal processing of this embodiment.
The light receiving elements 21, 11, 23 and tsh shown in FIG. 7 are input to the amplifiers 110, 111, 112 and Its, respectively.

These four amplifiers 110 to 113 are connected to the light receiving element 21.1.
If the amounts of light incident on 1, 23, and 18 are equal, the output signals 1, 1, - 1, and 1 are made to be cape-like.

The comparator 114 compares the output signal . . . with the slice voltage Vs as 9 levels 8L shown in FIG. . Ratio 1! i! 115 compares the slice voltage VJ as the level 8L shown in the output number .

In addition, in order to distinguish between the scattered light generated on the front side and the back side of the photomask 5 due to foreign matter and edges, amplifiers 111i and 111i are used to increase the output signals ・3 and ・ati, respectively.
17. This amplification degree has a value of 1. One value in the range of ~2s, for example, is set to 2.

The comparator 1111 compares the output signal . and the output signal of the amplifier 116, and outputs a logical value til't- only when "e,)K." It compares the signal ., with the output signal of the amplifier 117, and outputs a logic value "1" to e,2 when @4. The respective outputs of the comparators 114, 115, 118, and 119 are input to the AND circuit 120, and when the AND is established, a logical value "lJ" is generated which indicates the presence of foreign matter as an inspection result. Also, the slice voltage vS VSvn is output from the slice level generator 121, and its magnitude changes in response to the scanning signal SC, as in the first embodiment.

However, the individual magnitudes and changes a[ of the slice voltages VJ and S are slightly different.

This will be explained with reference to FIG. 10 (a-b). FIG. 10(a) is a perspective view of FIG. 7 when looking 1.1 above the photomask 5. FIG.

Here, in the scanning range of the laser beam 1 on the photomask 5, the central part is at the position *Ct, and both ends are at the positions Ct.
I, CI. As described above, the distances from the light receiving elements 21 and 11 to the position CI are both equal. Therefore, the following description assumes that the same foreign matter is attached to positions CI, CI, and CI. If a foreign object is attached to position CI,
The light receiving element 21.11 detects the scattered light generated from the foreign matter.
Since the solid angles of light reception are almost equal, the signal e1
,・The size of the wealth is also almost the same. Therefore, the laser beam 1
When the spot of is at position CI, the slice voltage VJ is vj! are set to be of equal size.゛If a foreign object is attached to position C7, the light receiving element 21
The amount of light received by the light receiving element 11 is greater than the amount of light received by the light receiving element 11. For this reason, the signal level is larger than the signal level, so the slice voltage must be set to Vsl>qs.

However, since the positions CI are far from each light receiving element 21.11, the signals 6, e! There is no big difference in size. Therefore, the slice voltage is -C(VJ, with no difference in magnitude from -tL), Vs, f is satisfied, and (M[C,
It is set to be smaller than the next slice voltage.

On the other hand, if a foreign object adheres to the position C, the position K Cs will be placed closest to the element 21, so the signal will be 0.
is an extremely large value.

In addition, since the solid angle of light receiving element 11 and the position C1 changes greatly with respect to the position 11ct and Ct, the signal e is 4. It will be a small value. For this reason, the slice voltage is v
S, ) Vs, are determined to be larger than the slice voltage at Kct.

FIG. 10(b) shows how each slice voltage changes with respect to the positions C1 to C8 described above.

In FIG. 10(i), the vertical axis represents the thick δ of the slice voltage, and the horizontal axis 6c represents the position of the scanning range.

As mentioned above, the magnitudes of the slice voltages vS and S are both equal at the position C1, and the magnitudes of the slice voltages vS and S are equal at the position C1
zE C-, VJ Tomi) Continuously changes so that vS, > Vsl at VSH1st *C5If-. This change is not necessarily linear, but often becomes -1 like the change in slice voltage Vj. In order to obtain this curved change, a conversion circuit having logarithmic characteristics, a polygonal line approximation circuit, or the like may be used as the slice level generator 121.

Next, the operation of the nine circuits shown in FIG. #I9 will be explained.

This scattered light has strong directivity compared to the scattered light generated from the edge portion of the pattern, and for example, assume that the amount of light received by the light receiving element 11 is greater than the amount of light received by the light receiving element 21. This ninth output signal ・1 and ・becomes a fist, 〉・,. Furthermore, as shown in FIG. 2, the amount of light received by the light receiving elements 23.13 is approximately equal to the amount of light received by the paired light receiving elements 21.11, respectively, and the output signals ・1 and ・4 Fi, ・Luki 1
,・4ki・becomes a proverb. This ninth, ・t < x・5, ・
l<K@4, and the comparison @118.11. both output a logical value "0". Therefore, the AND circuit 120 generates three logical values of "0" for the scattered light from the edge portion.

In addition, when scattered light is generated from foreign matter attached to the patterned surface of the photomask, both the output signals 1, , and Fi become larger than the slice voltages yg, , vg, and the output signals 1, , and 1/3 for output signal・2,・・
~1/8 times the size. Then, the output signal・1,・
, or since K is set to 1.5 to 2h5, ・1>KI・t>X0. Therefore,
The comparison circuits 114, 115, 118, and 1111 all output a logic value "l", and the AND circuit 120 outputs a logic value "1".

When scattered light is generated from a foreign substance layered on the back surface of the photomask, as shown in FIG. 3, the amount of light received by the light receiving system μ4 of the light receiving element 73.13, the light receiving element 21, and It becomes larger. This mourning must be... + < KIl , 1 (KI
4, and the outputs of the ratio IIIR units 11B and 1111 both have a logical value of "0". Therefore, 14@ attached to the back side
In contrast, the AND circuit 120 outputs a logical value of "0".

As described above, according to the embodiment of stripe 2, the pair of light receiving elements 11.130 and the light receiving element 21.23 are arranged so that the scattered light generated at the edge portion of the 1/< turn is selectively and strongly received.
Since two pairs are provided, even on a photomask having a complicated pattern, it is possible to avoid the influence of scattering due to the pattern and accurately detect only the attached foreign matter.

Next, as a third embodiment of the present invention, a configuration in which the configuration of the detection circuit in the second embodiment is changed will be described with reference to FIG. The basic configuration is the same as the detection circuit described in the second embodiment. However, in this embodiment, among the light receiving elements 21.11 arranged on the laser beam incidence side, we focused on the light receiving element with the smaller output force, It is configured to determine whether the output ratio is more than twice as high as that of the light-receiving element disposed in the photodetector.

In FIG. 11, components that have the same functions and operations as those in FIG. 9 are designated by the same reference numerals #i. Therefore, a configuration different from that in FIG. 9 will be explained. Amplifiers 110, 111
Each output signal "IX@mushroom" is input to the \con/<rator 130 to detect the magnitude of the output signal eaXel.For example, when @>61, the comparator 130 outputs the logical value [l
Output J, ・1ku・! When this happens, a logical value of "0" is output. The 11 outputs of the comparator 130 and the inverted output of the comparator 130 are connected to one of the AND gates 133 and 132, respectively.

Also, for the input of the AND gate 132.133,
The output signals from the ratio IIR devices 118 and 1111 are respectively connected. Each output signal of the AND gates 132 and 133 is inputted via an off gate 134 to an AND circuit 126 that generates a test result.

In such a configuration, for example, if the amount of light received by the light receiving element 21 is larger than the amount of light received by the light receiving element 11 (due to scattering at the edge of the pattern, etc.), the output signal
◎For this reason, the comparator 130 is the same as Theory 11 ([rl
J is output, AND gate 132 is closed, and AND gate 133 is opened. Therefore, at this time comparator 118.1
18 are both outputting a logic value "1", for example, only the output of the comparator 119 is applied to the OR gate 134 via the AND gate 133. In this way, orgate 13
The output of the light receiving element 21.11 which receives a smaller amount of light and the paired light receiving element (element 23.11).
13], the result of determining whether it is a foreign object or an edge portion is inserted.

As described above, selecting the smaller of the output signals 11+ and 6 as in Example 9 means selecting the light receiving direction where the influence of scattering of the circuit pattern is small. Prevents scattered light from entering the light receiving system in only one direction, causing saturation of the signal processing system and, in turn, saturation of the output signal of the amplifier, making it impossible to compare the intensities of the front and back light receiving systems of the object to be inspected. If there is an error in the geometric arrangement of the condensing lens of the light receiving system that looks into the front and back of the photomask, and the light condensing directions on the front and back are not completely symmetrical, foreign matter may occur. There is also the benefit of reducing false positives.

In the above embodiment, the comparators 118 and 119 are
For photoelectric signals such as those shown in Fig. 4 (1) (b),
-Ke@%@l- is determined by @, and the output is determined depending on whether the result is positive or negative. However, by using a divider or the like, we calculate the ratio between ・, and @s and ・, and,
Even if a circuit is provided to determine whether the result is greater than or equal to 0, the same function as the above embodiment can be achieved.

Next, a fourth embodiment of the present invention will be described with reference to FIGS. 12 and 13. This embodiment is provided with one more light receiving element 31 in addition to the second embodiment, to further reduce shadowing of scattered light from the pattern.

12, the difference from the configuration in FIG. 7 is that the condenser lens 30 and the light receiving element 31 are replaced by the lens 20. The lens 1G is arranged so that the surface of the photomask 5 on the laser beam incident side, that is, the pattern surface, can be seen from the direction opposite to the optical axis of the lens 1G.

Here, the relationship between the optical axes of the lenses 10, 20, and 80 will be described. The three lenses 1@, 20, and 30 have the same optical properties, and the three light receiving elements 11, 21, and 30 have the same optical properties.
Assume that the marginality of is also the same. Also, each optical axis is 4.1
Let %L@, t@. ft, the axis ts, and tl are both set at a small angle with respect to the pattern surface of the photomask 5, for example, around 10 to 306 degrees below t. Maku,
υ - Each light receiving element -7-1 from the center of the scanning range of 1
The distances to 121 and 31 are both set equal.

In the figure, when the photomask 5 is viewed from above, the optical axis t coincides with the longitudinal direction (scanning direction) of the scanning range, and the optical axis 1. ．． 1. is set at a small angle relative to the scanning range, for example around 30''.

In this way, by determining the optical axes L+, At, and As, the scattered light generated at the edge of the pattern is 3
Of the two light receiving elements IL21.31, almost no light is received by one of the light receiving elements IL21.31. 9. As a general tendency, the scattered light from the edge of the pattern is
1. When the light is strongly received at both 21 and 21, the light receiving element 3
1, the amount of light received is extremely small. t7'c14 Since scattered light is generated omnidirectionally from an object, each light receiving element 11.21
．． The amount of light received by No. 31 will be approximately the same. Stiff light receiving amount element 3
The output of 1 is processed by the detection circuit shown in FIG. It is basically the same as the detection circuit shown in FIG. Light receiving element 3
The output of 1 is input to a comparator 141 via an amplifier 140,
Ru. A nine slice voltage Vs is input to the comparator 141 from the slice level generator 121 in response to the scanning signal 8C in response to the laser spot position. This comparator 14a receives the output signal e of the amplifier 140.

exceeds the slice voltage V'st, the logical value is "-1",
In other cases, a logical value of "0" is output.

The other circuit elements in FIG. 13 are the same as in the third IIA example. This fourth embodiment has a difference of 1 compared to the third embodiment.
Light receiving system with two redundant directions (light receiving element 31, lens 30)
Therefore, the probability that the scattered light 'r#14 caused by the circuit pattern will be detected as a foreign object is extremely small.

Since the light receiving element 11.21 and the light receiving element 31 are looking into the central part of the scanning range from opposite directions, the slice voltage Vj.

The tendency of change in slice voltage S is set to be opposite to VJ. In other words, the above-mentioned figure 11110 (m
Slice voltage v5 at e). The slice voltage vss is obtained by reversing the slope of .

FIG. 14 is a block diagram illustrating a detection circuit according to a $115 embodiment. -C1 differs from the fourth embodiment in that three comparators 150, 151, 152, an AND circuit 153, an OR circuit 154, and a slice voltage vS,
,Vj,,Vj.

This is due to the addition of a slice level generator 160 that generates roughly two voltages.

The two voltages of the combined slice voltage maintain a predetermined difference from each other,
It changes depending on the scanning signal SC.

pre7mp110. lit, 140 output signal '81%
, el are respectively Converley! 1501151.152, the slice voltages Vs, , V, 5.
, Vs. At this time, the comparator 150,
The slice voltage applied to 151 and 152 is the comparator 114.
．． Higher than the slice voltage manually applied to 115.141,
No matter where the scattering of light due to the circuit pattern occurs strongly, the output signal ・1, el, ・.

is set higher than the minimum value of Therefore, comparators 150, 151, 152 and AND circuit 1
53, the AND circuit 153Fi generates a logical value r'IJe only when very strong scattered light is generated from a foreign object.

The output of the AND circuit 153 is input to the OR circuit 154 together with the output of the ant circuit w112G. Therefore, OR circuit 15
No. 4 outputs a logical value "l" when a foreign object is detected as an inspection result, regardless of the size of the foreign object. There is the following I# image compared to each of the above embodiments. Due to scattering by foreign objects,
A large photoelectric signal enters the signal processing system, and the output of each amplifier becomes close to the power supply voltage.
3.11 amplifiers 112 and 113 outputs are doubled and amplified! Comparison to compare the size of output from 110 and 111! 1ii118.1111 does not work correctly,
If the comparator 111119 operates as if it had detected light from both '::common circuit patterns even though the light is scattered from a foreign object, the foreign object cannot be detected in other embodiments, but In this embodiment, detection is possible. It is the comparator 11 that performs the comparison with the low slice voltage as described above.
In addition to 4.115.141, a comparator 15o1151.152 is provided for comparison with a high slice voltage,
This is because foreign matter that causes strong scattered light is detected by this comparator.

Increasing the force, i.e., contributes to detecting smaller foreign objects, while using a higher slicing voltage
This contributes to preventing false detections due to amplifier saturation, etc. Therefore, there is an advantage that weak scattered light from smaller foreign objects can be detected, and only foreign objects can be accurately detected even in the case of strong scattered light. This means that the foreign object detection range can be expanded.

The detection circuit according to the fifth embodiment has been described above using an example in which the number of light receiving elements is three on the laser beam incident side of the object to be inspected and two on the opposite side. It goes without saying that if there is one or more light receiving elements on the side, it can be configured to have the function intended in the fifth embodiment.

f9$111, 13.14 In the diagram, a comparator 130, an AND gate 132, 133, and an OR circuit 13
4 is used, but as shown in Fig. 11E9, the comparator 11B,
118 may be directly applied to the AND circuit 120.

Next, a sixth embodiment of the present invention will be described based on FIG. 15. In this embodiment, in addition to the 50th lens, another light receiving element 41 and a condensing lens 40 are provided.

The optical axis of this lens 400 is set to be plane symmetrical to the optical axis of the lens 3o with respect to the patterned surface of the photomask 5. Of course, the optical axis of the lens 4° is determined so that the central part of the scanning range is viewed from the back surface of the photomask 5. In this embodiment, each photoelectric signal of the light receiving element 11, 21, 31 that receives the scattered light from the laser beam incidence side is compared with each slice voltage in the same way as in the previous embodiment, and the AND is calculated. It is processed. This determines whether the scattered light from the edge portion of the pattern is the scattered light from a foreign object. - The photoelectric signal of the light-receiving element 13.23 for processing the scattered light from the back surface of the photomask 5 may be processed by the detection circuit as in the above-mentioned embodiment, but a simpler detection circuit may be used. It can be processed by

For example, the photoelectric signal of the light receiving element 13.23.41 is processed by a circuit configured similarly to the detection circuit of the light receiving element 11.21.31. In this way, if the light receiving element 11.21.31 on the laser beam incidence side detects a foreign object and the light receiving element 13.23.41 on the back side also detects the foreign object, the foreign object will be removed from the photomask 5. 11': '1. ,,1. j Can be distinguished. In this case, there is an advantage that the size of the foreign object can be determined extremely accurately by considering the peak value of the photoelectric signal of each light-receiving element when the foreign object is detected on the front side and the back side of the photomask 50.

When the detection circuits in the fourth and fifth embodiments are used as they are, a switching circuit 200 as shown in FIG. 16 may be provided. This switching circuit 200 switches each photoelectric signal of the light receiving element 11, 21, 31 on the laser beam incident side and each photoelectric signal of the light receiving element 13, 23, 41 on the back side, and outputs a signal. is configured to occur. Of course, it is better to perform this switching after the photoelectric signals of each light receiving element have been amplified once. This switching is done by signal 201
This is done by With this configuration, when inspecting the back side of the photomask 5, for example, the operation of turning the photomask 5 upside down and cutting it is unnecessary. For this purpose, the laser beam 1 may be guided by an appropriate external path switching member in the same way as the front side is irradiated onto the back side of the photomask 5 in FIG. 14.

Therefore, in response to switching of the switching member, the signal 201
By changing the photomask 5, it is not necessary to turn the photomask 5 over, so foreign substances attached to both sides can be detected very quickly and accurately.

Next, a seventh embodiment will be described. In the seventh embodiment, the arrangement of each light receiving element is assumed to be the same as that in FIG. 7 used to explain the second embodiment. As explained earlier with reference to FIG.
), but the scattered light from the foreign matter j adhering to the light shielding part 5b is detected only by the light receiving part (4) and not by the light receiving part (B). This thing,
17(a), (b), (e), and (d) are the photoelectric signals from the light receiving elements 21, 11, 23, and 13, respectively. The vertical axis represents the size, and the horizontal axis represents time, and the horizontal axis also corresponds to the laser spot position. Here, when the laser beam is scattered by a foreign object j as shown in Figure @1, the light receiving elements 21 and 11 are
a) Generate photoelectric signals A3 and B3 as shown in (b). −
As shown in FIG. 17(e) ((1), the light receiving elements 23 and 13 output substantially zero as photoelectric signals 03 and C3, respectively.

Further, when the laser beam is scattered by J%*i as shown in FIG. 1, the light receiving element 21.1 as shown in FIG.
1.23.13Fi each party electric signal 4, B4, C4, C
Generates 4. That is, as shown in FIGS. 17(e) and 17(d), each photoelectric signal C4, C4tlj of the light receiving element 23.13
You will get some output, not zero. Same, Pmu 4,
PH1, pc◆, PO4 are photoelectric signals A4, B4, C4%
These are each peak value of C4. Therefore, if the small slice voltages vs4, vs, are set between the peak values PC4, PO2, respectively, in the case of the amount of foreign matter, both the light receiving element 23 and 130 electric signals exceed the slice voltage vs6, but there is one difference.
In the case of j, the slice voltages do not exceed Vs4 and vs5, and the amount of foreign matter and j can be distinguished. Therefore, next, a seventh embodiment will be specifically described.

FIG. 18 &-1 is a block diagram of signal processing in this embodiment. In FIG. 18, light receiving elements 21.11.23.13
, amplifiers 110 to 113, comparators 114 and 115
．． 11B, 119 and amplifiers 116, 117 have the same function as the circuit in the second embodiment of FIG. The difference is that converters 9204 and 205 are provided, and their outputs are input to AND circuit 202 in parallel. The comparator 204 is the amplifier 11
2's output est - slice voltage Vs output from the slice level generator 203, and if e,>■54, then logic f! J value "1", otherwise logical value 1' O
The comparator 205 compares the output of the amplifier 113 with the slice voltage vSI, and outputs e4
If so, then Fi logical value Ill, otherwise logical value fO,
" is output.

, 1 Here, the magnitude of the slice voltage vS, vS, is determined as explained in Fig. 16 above, and the magnitude changes depending on the spot position. The change is the first thing to happen.
- As explained in each of the sixth I embodiments. In such a configuration, if the laser beam hits a foreign object attached to the glass plate (light transmitting part), the comparator 204
．． 205 outputs the logical value "1" and other comparator 1
Since 14.115.118.119 also outputs a logical value of "1", the output of the AND circuit 202 becomes a logical value of "1", indicating that a foreign object has been detected. However, when the laser beam enters a foreign object attached to the light shielding part 1, the comparator 2
The output of 04.205 becomes a logic value "0", and the output of the AND circuit 202 becomes a logic value "0". Therefore, the presence of a foreign object can be detected only when the foreign object is attached only to the transparent part, and the mask Foreign matter attached to the m-base part that does not affect the printing of the pattern can be ignored. 1′
,・,.

,:' In this way, compared to the case where the foreign matter is detected without distinguishing whether the place where the foreign matter is attached is the original transmitting part or the light shielding part, in this embodiment, the foreign matter is attached only to the light shielding part (2 times 1 cleaning of the photomask N' Even though W can be used to burn a pattern, it is assumed that it is contaminated and is washed again.
It is necessary to replace the photomask with another one with the same pattern or to reduce the amount of damage. For this reason, there is a percentage value that is advantageous in terms of time and economy in the M construction of Ushihiro body electrical equipment.In this seventh embodiment, the comparator 204.2 (
The outputs of 75 are both input to the AND circuit 202.
4t of the output of either comparator 204 or 205
AND1 and 2 (32 are manually input and ℃ is also ↓.) The configuration may be simple, but it also has the disadvantage that it is prone to malfunction if -10,000 noise enters the original 'vt1'. It is also possible to OR't the monkey comparator 204 and the 2tjjM/J% output, and the result is ?r: 7n F times 202 v (- input.

As mentioned above, this embodiment of cocoon 7 is the fruit of striped 2.
Although we have explained that the difference is that a layer is added only to the original transparent part, 8-Detection'T core has a new function added.
It goes without saying that this function can be similarly added to each of the first, third to sixth embodiments.

In each of the embodiments described above, the light-receiving element that receives the scattered light generated on the laser incidence side and the light-receiving element that receives the scattered light generated on the back side are arranged symmetrically with respect to the surface of the object to be inspected. ing. ” This is because a photomask is used as the object to be inspected, and for example, when inspecting an object that has no edges, even if it has a pattern drawn on a transparent substrate with a light-shielding part. A pair of light-receiving elements that look into the mating part and the back side of the board do not necessarily need to be arranged symmetrically in the plane.In addition, a plurality of light-receiving elements that look at the surface on the laser beam incidence side are provided, and one light-receiving element that looks at the back side is provided. In addition, in the detection circuits of the above embodiments, the slice voltage was changed according to the spot scanning position of the laser beam. If the change in the received solid angle of scattered light is small, the slice level is constant and does not need to be changed.Also, even if the vertical angle of scattered light reception changes due to laser spot scanning, it is not necessary to change the slice voltage. However, by changing the gain of the photoelectric signal transmission system in accordance with the laser spot scanning position, that is, in synchronization with the scanning signal 80, the slice voltage can be fixed at a constant value.

In this way, when controlling the gain of the transmission system,
For example, the slice voltages vS, ,V in Fig. 9.11
't is a common constant voltage. And amplifier 110,
The gain of the laser beam 111 is made variable according to the spot position of the laser beam 1. As an example, the relationship between each gain of amplifier 1101111! It is preferable to set it as shown in FIG. This figure corresponds to the above-mentioned Figure 10(b), but the position CIWc-M is set, and the gain G of the amplifier 110 and the gain νG of the amplifier 111 are both made equal. The gain at this time is normalized to 1.

For example, at the position C1, the gain G1 is approximately twice the gain of 5 at the position C1, and the gain G is 1.
The gain G is set to 2 to L5 times, and the gain G at position C1 is 0.2 to α4 times the gain at position CI.

is 0. ? It is preferable to set it to ~α9 times.

In each of the above examples, the ratio of the outputs of a pair of light-receiving elements provided correspondingly to the front and back sides of the object to be inspected was compared to a certain value, but in the example, Light receiving elements 11 and 21
The sum of the output of
By determining whether it is larger than that, it is possible to identify whether it is a foreign object or a circuit pattern, or to determine whether it is a foreign object attached to the laser beam incident on the laser beam.

Also, since there is a correlation between the size of the foreign object and the magnitude of the scattered signal, it is also possible to detect the foreign object and find out the size of the foreign object from the peak value of the photoelectric signal at 9 o'clock. In this case, the signal to be used for determining the peak value may be the sum of the outputs of multiple light receiving elements on the laser beam irradiation side, or it may be the signal from a single photoelectric element. Even if there is
stomach.

Further, by determining the moving position of the object to be inspected and the position of laser spot scanning when the object is detected, it is also possible to know the location of the foreign object on the object to be inspected.

As described above, according to the present invention, -scattered light is photoelectrically detected on the front side and back side of the object to be inspected, and l4qlJ inspection is performed based on the difference in the photoelectric signals. It is possible to selectively and accurately detect whether it is attached to the front or back of the paper6.

9. Especially when inspecting photomasks and reticles for IC manufacturing, multiple light receiving elements are arranged in different directions and the original beam is made obliquely incident, which prevents the influence of circuit patterns and detects only foreign objects at high speed. can do. Furthermore, the size of the foreign object can be detected from the correlation between the intensity of the scattered light and the size of the foreign object, and only foreign objects that are truly harmful can be detected. Therefore, by detecting even smaller foreign objects than necessary, it is possible to prevent a reticle or a mask that can be used for exposure from being contaminated and having to be re-cleaned after being determined to be good.

The present invention can be used not only to detect foreign matter attached to a readicle mask, but also to detect foreign matter on an object such as a transparent object with a pattern adhered to it. Therefore, the present invention can be used to manufacture precision patterns that are free from adhesion of foreign matter such as dust. It is also very useful for time inspection.

[Brief explanation of the drawing]

1vA is a diagram showing the scattering of laser light by foreign matter on the surface of the photomask on which the pattern is drawn; FIG. 2 is a diagram showing the scattering by foreign matter adhering to the glass plate and the scattering by the edge part of the light shielding part; Fig. 3 is a diagram showing the state of scattering due to foreign matter adhering to the front and back surfaces of the transparent part of the glass plate, Fig. 4 is a diagram showing scattered light received by the light receiving part shown in Fig. 3, and Figs. Figure 6 is a diagram showing an example of a foreign matter inspection device that is the starting point of the present invention, Figure 7 is a diagram showing a foreign matter inspection device, and Figure 8 is a diagram showing the photoelectric output of each light receiving element due to scattered light from foreign matter. , Figure 9 is a diagram showing the detection circuit, Figure 1θ (A) is a top view of the photomask, Figure 10 (
b) is a diagram showing changes in slice voltage, FIG. 11 is a diagram showing the first embodiment of the present invention, FIG. 12 is a diagram showing the second embodiment of the present invention, and FIG. 13 is a diagram showing the present invention. FIG. 14 is a diagram showing a detection circuit according to a second embodiment of the invention. FIG. 15 is a diagram showing a detection circuit according to a third embodiment of the invention. FIG. 15 is a diagram showing a fourth embodiment of the invention. 16 is a diagram showing a switching circuit, FIG. 17 is a diagram showing a photoelectric signal of a light receiving element, FIG. 18 is a diagram showing signal processing according to the present invention, and FIG. 19 is a diagram showing the gain of an amplifier. It is a diagram. [Explanation of symbols of main parts] 5...Object to be inspected 11.21...1st photoelectric means 13.23...2nd ft, electric means 130.131.118.119.132.133.1
34.120...detection device ill'(.,

Claims (1)

[Claims] 1. In f7i & electronics, one side of a light-transmitting object to be inspected is scanned with a light beam, and the presence or absence of attached foreign matter is inspected based on optical information generated from the object to be inspected. , looking at the one surface and arranged to receive the scattered light emitted from the one surface side; A second photoelectric means arranged to receive the scattered light emitted from the surface side; and a second photoelectric means; comparing both electric signal sounds of the eleventh second source means, a nine detection signal according to the state of foreign matter adhesion 11; A foreign matter inspection device comprising: a detection device that generates a foreign substance. 2. The foreign object inspection W&wax according to claim 1, wherein the eleventh second electric wire means are arranged so as to obliquely look into the one surface and the other surface i, respectively. & The first electric means includes a plurality of light-receiving elements arranged so as to look at the portion irradiated by the light beam on the one surface from different directions. Foreign matter inspection device described.