JPH06258237A - Defect inspection device - Google Patents

Abstract

PURPOSE:To prevent a lighting area from spreading out of the area to be inspected on a subject and to prevent dispersion in defect detection sensitivity from generation following dispersion of the illumination intensity distribution. CONSTITUTION:A light beam L1 from a light source 1 is magnified in the X- direction by lens systems 6A, 7A to irradiate a light shielding plate 16, in which an opening 19 is formed, and a light beam L8 passing through the opening 19 irradiates a slit-shaped lighting area 20 extending in the X-direction on a reticule 1. The reticule 1 is moved by using a driving device 3 in the Y-direction to the lighting area 20, while the X-directional edges 19a, 19b of the opening 19 in the light shielding plate 16 are set to be parallel to the direction crossing the Y-direction respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reticle or a photomask used as an original plate when manufacturing a semiconductor device or the like in a photolithography process, or a foreign substance adhered to the surface of a dustproof film (pellicle) of these original plates. The present invention relates to a defect inspection apparatus suitable for application when inspecting defects such as.

[0002]

2. Description of the Related Art A reticle or photomask as an original plate (hereinafter referred to as a "reticle") when a semiconductor device, a liquid crystal display device, or the like is manufactured by a photolithography process.
There is used an exposure device that transfers the pattern formed on the photosensitive substrate through a projection optical system. If a foreign substance larger than a predetermined standard adheres to the pattern forming surface of the reticle or the surface opposite to the pattern forming surface, or if the pattern on the pattern forming surface has a defect, the pattern formed on the photosensitive substrate is defective. Therefore, before mounting the reticle on the exposure apparatus, it is necessary to inspect the presence / absence of a defect including a foreign substance, the position of the defect, the size of the defect, and the like. Further, in order to prevent foreign matter from directly adhering to the pattern forming surface of the reticle, a dustproof film called a pellicle may be stretched on both sides (or one side) of the reticle.
Regarding the reticle with the pellicle stretched in this way,
It is necessary to inspect the presence / absence of a defect including foreign matter on the surface of the pellicle, the position of the defect, and the size of the defect.

FIG. 5 shows an example of a conventional defect inspection apparatus. In FIG. 5, the reticle 1 to be inspected is a stage 2
The table 2 is placed on the table, and the table 2 is configured to be movable in the Y direction by the drive device 3. The amount of movement of the table 2 in the Y direction is measured by the length measuring device 4 such as a linear encoder. .
The light beam L1 emitted from the light source 5 including the laser light source becomes a sheet-shaped light beam L2 expanded in the X direction substantially perpendicular to the Y direction by the negative cylindrical lens 6 and the positive cylindrical lens 7. The light beam L2 is applied to the slit-shaped illumination region 8 extending in the X direction on the surface of the reticle 1.

If a defect 9 such as a foreign substance exists in the slit-shaped illumination area 8 on the surface of the reticle 1, scattered light L3 is generated from the defect 9 by the light beam L2, and this scattered light L3 is generated. Is collected by the light receiving lens 10 and an image of the defect 9 is formed on the image pickup surface of the one-dimensional image pickup device 11 such as a one-dimensional CCD. The X-direction coordinate of the defect 9 on the reticle 1 is converted by the number of the light-receiving pixel of the one-dimensional image pickup device 11 that receives the light, and the Y-direction coordinate of the defect 9 is measured by the length measuring device 4 at that time. It can be obtained by long output. Further, since the one-dimensional image pickup device 11 outputs a pixel output signal having a size proportional to the amount of received light, the rough size of the defect 9 can be determined by the size of the pixel output signal. Therefore, the inspection result can be displayed, for example, as a table in which the defect size is associated with the X coordinate value and the Y coordinate value of the defect, or as a map of the defect on the display screen of the CRT display.

However, in the conventional defect inspection apparatus of FIG. 5, when inspecting a defect on the upper surface 1a of the reticle 1, the light beam L2 is transmitted through the reticle 1, and the transmitted light is the lower surface of the reticle 1. There is an inconvenience that the light is diffracted by the fine circuit pattern on 1b, and the diffracted light is condensed by the light receiving lens 10 as scattered light from the defect and is detected by the one-dimensional image sensor 11. Therefore, in particular, when inspecting the surface of the reticle 1 facing the surface on which the circuit pattern is formed, a configuration as shown in FIG. 6 may be adopted.

FIG. 6 shows another conventional defect inspection apparatus. In FIG. 6, a light beam L4 emitted from a light source 12 composed of a laser light source has a negative cylindrical lens 13.
The sheet-shaped light beam L5 is generated by being expanded in one direction by the condenser lens 14. And this light beam L
5 is obliquely irradiated to the slit-shaped illumination area 15 extending in the X direction on the surface to be inspected of the reticle 1 at an angle α, and scattered light from a defect in the illumination area 15 passes through the light receiving lens 10. It is detected by the one-dimensional image sensor 11. Angle α is 5
When the angle is less than or equal to 0 °, the transmittance of the reticle 1 is significantly reduced, so that the incident light beam L5 is hardly reflected and does not reach the lower surface 1b on which the circuit pattern is formed. Therefore, the amount of diffracted light from the circuit pattern also becomes small, and the diffracted light from the circuit pattern will not be erroneously detected as scattered light from a defect on the reticle 1.

[0007]

In the prior art as described above, a laser light source is used as the light source 5 or the light source 12. Since the laser light source has high brightness, even if the slit-shaped illumination area 8 or 15 is formed, the amount of light per unit area in the illumination area (hereinafter, referred to as “illuminance”) becomes large, and thus minute defects are generated. This is because it is possible to reliably detect scattered light from. However, the light beam emitted from the laser light source has the highest brightness at the center of the light beam, which is called a Gaussian beam, and the brightness decreases concentrically toward the periphery. Therefore,
The illuminance distributions of the illumination area 8 and the illumination area 15 of FIG. 6 are also lower toward the periphery.

FIG. 7 (a) is an illuminance distribution S (Y) in the Y direction on one cross section of the illumination region 8 in FIG. 5, and FIG. 7 (b) is a cross section of the one cross section of the illumination region 8 in the X direction in FIG. Shows the illuminance distribution S (X),
As shown in FIG. 7B, both end portions 8a and 8b in the X direction are
The illuminance at is much smaller than that at the center. The illuminance distribution of the illumination area 15 of FIG. 6 is also the same. In this case, the moving speed of the stage 2 by the drive device 3 of FIG.
If the speed is such that scattered light by the light beam at the peak of the illuminance distribution in the Y direction in FIG. 7A is always detected at an arbitrary point to be inspected, the reticle 1 is always substantially uniform in the Y direction. The light beam is emitted with the illuminance of.

However, in the X direction of the reticle 1, the illuminance is high near the center of the reticle 1 and the illuminance is low at both ends 8a and 8b in the X direction. Even if a defect that may occur exists on the reticle 1, the value of the pixel output signal of the one-dimensional image pickup device 11 takes different values depending on the attachment position of the defect in the X direction. Therefore, when estimating the size of the defect from the value of the pixel output signal, there is a disadvantage that a large error occurs due to the attachment position of the defect in the X direction.

For such inconvenience, the position in the X direction,
That is, by multiplying the output signal of each pixel by the reciprocal of the illuminance in the X direction as a correction coefficient in accordance with the address of the light receiving pixel of the one-dimensional image pickup device 11 (a numerical value indicating the number of the pixel), the position in the X direction can be changed. No output is obtained. However, when the correction method as described above is applied to the defect inspection apparatus as shown in FIG. 6, since the light beam L5 is obliquely incident on the reticle 1 at an angle α, the height of the reticle 1 in the Z direction is temporarily increased. Changes by Δh, the illuminance center of the illumination area 15 on the reticle 1 (the position in the X direction on the reticle 1 where the maximum illuminance is obtained) is eccentric by (Δh / tan α). For example, α
= 5 °, the surface of the reticle 1 is displaced by 1 mm in the Z direction, and the illuminance center is 1 mm / tan 5 °, that is, 11 m.
It will be offset by m. Therefore, the illuminance on the reticle 1, especially on the left and right, may change by a fraction to several times depending on the case, and naturally the pixel output signal of the one-dimensional image pickup device 11 also changes at this ratio. In other words, a change in the height of the reticle 1 causes a change in the detection sensitivity especially on the left and right in the X direction.

The above-mentioned inconvenience is caused by the fact that the illuminance distribution in the X direction on the reticle 1 has a mountain shape (Gaussian distribution) as shown in FIG. 7B. This can be solved by making the illuminance substantially uniform regardless of the position in the X direction. As a method of making the illuminance distribution uniform, it is recommended to increase the magnification of the lens groups 6 and 7 in FIG. 5 and the lens groups 13 and 14 in FIG. 6 so that only the central portion of the Gaussian distribution is used. Good. However, if the light beam is simply expanded and applied to the reticle 1, the light beam is also applied to the vicinity of the side faces 1c and 1d of the reticle 1 and the stage 2, and strong scattered light is generated from these parts. There is a new inconvenience that the light cannot be distinguished from the scattered light from the defect. Therefore, as a further measure, it is conceivable to block both ends of the expanded light beam with a light blocking plate.

FIG. 8 shows a main part of an apparatus in which such a measure is applied to the apparatus of FIG. 5. In FIG. 8, a light beam L1 having a Gaussian distribution emitted from a light source 5 composed of a laser light source is The negative cylindrical lens 6A and the positive cylindrical lens 7A expand in the X direction to form the light beam L6. The light beam L6 is applied to the light blocking plate 16 having a rectangular opening 17 elongated in the X direction, and the light beam L7 obtained by blocking both ends of the light beam L6 in the X direction with the light blocking plate 16 is a reticle. X on 1
Irradiation is performed on a slit-shaped illumination region 18 extending in the direction. As a result, the illuminance unevenness in the X direction within the slit-shaped illumination area 18 on the reticle 1 is reduced, and the reticle 1
It is also possible to prevent the light beam from being irradiated near the side surfaces 1c and 1d, and unnecessary scattered light is not generated.

However, if the illuminating area of the light beam L6 is limited by the light shielding plate 16 as shown in FIG. 8, the diffraction effect when the light beam L6 passes through the rectangular opening 17 becomes a problem.
Here, assuming that the width of the Gaussian beam is defined by the width of the point where the illuminance becomes 13.5% with respect to the maximum illuminance, the width of the light beam L6 in the X direction is ΔX, The width in the Y direction is ΔY. Further, the rectangular opening 1 of the light shielding plate 16
When the length in the X direction (length in the longitudinal direction) of 7 is a and the width in the Y direction is b, the following relationship is established.

ΔX >> a (1) ΔY << b (2)

Therefore, since the diffraction does not occur in the Y direction in the opening 17 but only in the X direction, even if the width of the slit-shaped illumination region 18 in the X direction is approximately a, the illumination region 18 has the same width. The illuminance distribution S (X) in the X direction of FIG.
It is clear from diffraction theory that it has a fine structure as shown in. As shown in FIG. 9, the illuminance distribution S (X) in the X direction in the illumination area 18 changes in a sine wave shape particularly at both ends,
For example, the illuminance is a valley at the positions 18a and 18b in the X direction. Therefore, even if the reticle 1 is moved in the Y direction by driving the stage 2 using the driving device 3 of FIG. 5, the illuminance of the light beam is always weak at the positions 18a and 18b of FIG. However, there is a disadvantage that the sensitivity of is lower than that of other areas.

In view of the above point, the present invention provides a defect inspection apparatus which irradiates a slit-shaped illumination area on a test object with a slit-like illumination area and inspects a defect by scattered light from the illumination area. The object is to prevent the area from covering a portion other than the inspection target area on the inspection object, and to prevent variations in the sensitivity of defect detection due to variations in the illuminance distribution in the slit-shaped illumination area. .

[0017]

A defect inspection apparatus according to the present invention comprises, for example, as shown in FIG. 1, a light source (5) for generating a light beam and an object to be inspected () by expanding the light beam in a predetermined direction. 1) Light beam expansion means (6A, 7A) for irradiating the upper part
And scanning means (2, 3) for relatively scanning the light beam expanding means (6A, 7A) and the test object (1) in a direction intersecting the expanded direction of the light beam, and the test object. (1) It has a light receiving means (10, 11) for photoelectrically converting scattered light generated from the above defect (including a foreign substance), and inspects the defect based on the photoelectric conversion signal obtained by this light receiving means. In the device, a plurality of edges (19) for limiting an illumination area (20) illuminated by the light beam on the object to be inspected (1) in a direction in which the light beam is expanded (X direction).
The light shielding means (16) having a, 19b) is provided, and at least one of the plurality of edges is parallel to the direction intersecting the relative scanning direction (Y direction).

In this case, one example of the shading means (16) is two opposing parallel edges (19a, 19b) for limiting the illuminated area (20) from both sides in the direction in which the light beam is expanded. And these two edges are substantially parallel to the direction intersecting the direction of their relative scans. Another example of the light-shielding means is, as shown in FIG. 4C, an opposing fan shape for limiting the illumination area from both sides in the direction in which the light beam is expanded (X direction). Two open edges (24a, 24b)
And these two edges are parallel to the direction intersecting the relative scanning direction (Y direction).

[0019]

According to the present invention, the light beam L1 having a Gaussian distribution emitted from the light source (5) is directed in a predetermined direction (this is defined as the X direction) by the light beam expanding means (6A, 7A). The expanded light beam L6 is incident on the opening (19) whose width in the X direction is limited by the plurality of edges of the light shielding means (16). The light beam L8 that has passed through the opening (19) is incident on the slit-shaped illumination area (20) extending in the X direction on the test object (1). The test object (1) can be moved in the Y direction relative to the illumination area (20) by the scanning means (2, 3).

FIG. 1 (b) is a view in the XY plane when the light beam L6 incident on the opening (19) is viewed from the light source (5) side. In FIG. 1 (b), the opening (19) is shown. ) The left edge (19a) and the right edge (19b) of
Both are tilted to the X and Y axes. For example, it is assumed that both the edges (19a) and (19b) are inclined by 45 ° with respect to the Y axis which is the scanning direction. When the light beam L6 passes through the aperture (19), the edges (19a, 19b)
Block the light beam L6, a diffraction effect is generated only by these two edges, and the edges (19a, 19a
Irregularity of illuminance occurs due to the diffraction effect in parallel with b). This is shown in FIGS. 2 (a) and 2 (b).

2 (a) and 2 (b) show a simplified illuminance distribution in the light beam L8 after passing through the aperture (19), that is, in the illumination area (20) on the object (1). , Fig. 2
(A) is, so to speak, a contour line of the illuminance in which a portion having the same illuminance in the illumination region (20) is connected by a solid line, and due to the diffraction effect, a direction parallel to the edges (19a, 19b) of the opening (19) (Y axis Streaks of uneven illuminance appear in the direction of intersection at 45 °. The illumination area (20) is a straight line PP parallel to the X axis.
The illuminance distribution in the X direction when cut at ′ is like the solid line distribution SP in FIG. 2B, and the illumination area (20)
2 is cut by a straight line QQ ′ parallel to the X axis, the illuminance distribution in the X direction becomes like the distribution SQ indicated by the broken line in FIG. Figure 2
As can be seen by comparing the distribution SP and the distribution SQ in (b), the illuminance at the position X1, which is a valley in the distribution SP, is
It is a mountain in the distribution SQ.

That is, if the object (1) and the illumination area (20) by the light beam are moved relative to each other in the Y direction,
The illuminance at the position X1 in the X direction changes according to the relative movement amount in the Y direction, but there is always a valley and a peak, that is, there are low illuminance and high illuminance. Become.
Therefore, by relatively scanning the inspection object (1) and the illumination area (20), the illuminance distribution on the inspection surface of the inspection object (1) becomes substantially uniform over the entire surface, and the defect detection The sensitivity is also uniform.

The light-shielding means (16) also has two opposing, substantially parallel edges (19) for limiting the illuminated area (20) from both sides in the direction in which the light beam is expanded.
a, 19b) and the two edges are substantially parallel to the direction intersecting the relative scanning direction, the shading means (16) is easy to manufacture. Further, the light shielding means has two opposed fan-shaped edges (24a, 24b) for limiting the illumination area from both sides in the direction in which the light beam is expanded (X direction). Each of the two edges has a relative scanning direction (Y
Even when the light shielding means is parallel to the direction intersecting the (direction), the light shielding means can be easily manufactured.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the defect inspection apparatus according to the present invention will be described below with reference to FIGS. In this example, the shape of the opening in the light shielding plate 16 of the device of FIG. 8 is improved. In FIG. 1, parts corresponding to those of FIGS. 5 and 8 are designated by the same reference numerals and detailed description thereof is omitted. To do.

FIG. 1A shows the structure of the defect inspection apparatus of this example. In FIG. 1A, the reticle 1 to be inspected is shown.
Is placed on the stage 2, and the stage 2 is moved in the Y direction by the drive unit 3, and the amount of movement of the stage 2 in the Y direction is measured by the length measuring device 4. Then, the light beam L1 emitted from the light source 5 made of a laser light source becomes a sheet-like light beam L6 expanded in the X direction substantially perpendicular to the Y direction by the negative cylindrical lens 6A and the positive cylindrical lens 7A. The light beam L6 is applied to the parallelogrammatic opening 19 of the light shielding plate 16. The light beam L8 that has passed through the aperture 19 is almost X-ray on the surface of the reticle 1.
The slit-shaped illumination area 20 extending in the direction is irradiated.
The scattered light from the defect including the foreign matter in the illumination area 20 is
An image of the defect is formed on the one-dimensional image pickup device 11 via the light receiving lens 10.

FIG. 1B is a plan view of the light shielding plate 16 of this embodiment as seen from the light source 5. As shown in FIG. 1B, the four vertices of the opening 19 in the light shielding plate 16 are Assuming A, B, C, and D, the edge 19a composed of the side AB and the edge 19b composed of the side BC are parallel to each other, and the edge 19a
And 19b are 45 ° in the Y direction, which is the relative scanning direction.
And the sides DC and AB are both parallel to the X direction. Further, both ends in the X direction of the light beam L6 are restricted by the edges 19a and 19b of the opening 19,
Side AB and side DC of Y with respect to the light beam L6, respectively.
Outside of the direction. Therefore, on the slit-shaped illumination area 20 of FIG.
The diffraction pattern is formed in the direction parallel to the edges 19a and 19b, but the diffraction pattern is not formed in the direction parallel to the sides AB and DC.

The illuminance distribution of the light beam L8 in the illumination area 20 on the reticle 1 due to the diffraction effect in the parallelogrammatic aperture 19 of FIG. 1B is shown in FIGS. 2A and 2B. Will be things. 3 shows a more detailed structure of the illuminance distribution of the light beam L8 in the illumination area 20 of FIG.
(A) is a kind of illuminance contour line in which the parts of the same illuminance in the illumination area 20 are connected by a solid line. The illuminance distribution S (X) in the X direction when the illuminance distribution in FIG. 3A is cut along the EE ′ line and the FF ′ line parallel to the X-axis is the solid line distribution in FIG. 3B. The distribution SE is SE and the broken line SF. In addition, the illuminance distribution of FIG.
The illuminance distribution S (Y) in the Y direction when cut along the lines 'and HH' is the solid line distribution SG in FIG. 3C, respectively.
And the distribution SH of the broken line. In this case, the stage 2 of FIG.
By moving in the Y direction, arbitrary points on the reticle 1 are illuminated by the illuminance distributions SE and SF shown in FIG. 3B, respectively. Is almost uniform. Therefore, the detection sensitivity of defects on the entire surface of the reticle 1 is substantially uniform.

By the way, as shown by the envelope 21 of the illuminance distribution in FIG. 3B, no matter how much the laser beam originally having the Gaussian distribution is expanded and viewed through the aperture, it is inevitable that some illuminance nonuniformity will occur. Absent. Of course, when the light shielding plate 16 having the opening 19 is applied to the oblique incidence system like the conventional device of FIG. 6, even if the height of the reticle 1 is changed, it is detected as compared with the case where the light beam having the Gaussian distribution is directly irradiated. Sensitivity is much less likely to change. In this example,
The remaining X as shown by the envelope 21 in FIG.
The illuminance non-uniformity in the direction is corrected by multiplying the pixel output signal of the one-dimensional image pickup device 11 in FIG. 1 by a correction coefficient which differs for each address of the light receiving pixel. Specifically, the one-dimensional image sensor 1
The reciprocal of the illuminance indicated by the envelope 21 for each address of one light receiving pixel may be set as the amplification degree of that address in the amplifier of the pixel output signal.

Further, the moving speed when moving the reticle 1 in the Y direction is such that at any position in the X direction on the reticle 1, when the intensity of scattered light is detected, the peak portion of the illuminance distribution within the illumination area 20 is always detected. It has to be illuminated. For example, when the entire light beam is viewed, as shown in FIG. 3A, if the width of the illumination area 20 in the Y direction is Δy and no diffraction pattern is generated, the step amount is Δy / 4 or less. By sending the reticle 1 in the Y direction, the illuminance unevenness in the Y direction can be suppressed within a width of 10%. On the other hand, in the present embodiment, the light beam in the illumination area 20 is shown in FIG.
As in (a), it has a two-dimensional distribution that is periodic in the diagonal direction.

Therefore, the width Δy _{G in} the Y direction of the distribution SG and the width Δy _{H in} the Y direction of the distribution SH shown in FIG.
(a value smaller than y) is regarded as the beam width in the Y direction, and the width Δ at an arbitrary position in the X direction on the reticle 1
The minimum value of y _G (or width Δy _H )
_G (X)) ”or“ min (Δy _H (X)) ”), min (Δy _G (X)) / 4 or less or min (Δy
_The reticle 1 must be sent in the Y direction with a step amount of _H (X)) / 4 or less. To summarize the above briefly, in the defect inspection apparatus using the light shielding plate 16 in which the deformed opening 19 is formed as in the present embodiment, the two-dimensional illuminance on the reticle 1 in the X and Y directions. The unevenness is determined by the shape of the opening in the light shielding plate 16 and the moving speed (the relative speed of the reticle 1 and the light beam in the Y direction).

Next, regarding the processing of the pixel output signal of the one-dimensional image pickup device 11 of FIG. 1, as the reticle 1 is moved in the Y direction, the illuminance of the light beam on the defect changes, and the defect is dealt with. Since the value of the pixel output signal to be changed also changes, the maximum value of the pixel output signal is taken in. That is, the pixel output signal of the one-dimensional image pickup element 11 when the illuminance distribution of the EE ′ line in FIG. 3A is located on the defect is higher than when the illuminance distribution of the FF ′ line is located on the defect. When the value is large, the larger value, the address of the light receiving pixel of the one-dimensional image pickup device 11 at that time, and the length measurement output of the length measuring device 4 are stored as data in a storage unit such as a memory.

Next, another example of the opening formed in the light shielding plate 16 of FIG. 1B will be described with reference to FIG. Figure 4
4A shows a case where a hexagonal opening 22 is formed in the light shielding plate 16, and in FIG. 4A, the opening 22 is formed.
The light beam L6 emitted from the cylindrical lens 7A shown in FIG. Further, two edges 22 on the left side of the opening 22 in the X direction that are substantially orthogonal to each other
The width of the light beam L6 in the X direction is limited by a and 22b and the two right edges 22c and 22d that are substantially orthogonal to each other. Edges 22a, 22b and 22c, 2
2d intersects each other in the Y direction at an angle, and the light beam L6 has the oblique edges 22a, 22b and 22c,
2d in a checkered pattern on the reticle after being diffracted by 22d.
Irradiate as light having a three-dimensional illuminance distribution. Therefore, as in the case of using the opening shown in FIG.
If it moves in the direction, the unevenness of the illuminance of the light beam in the X direction is eliminated.

FIG. 4B shows a case where the light shielding plate 16 is formed with openings 23 having arcuate ends.
In (a), both ends of the opening 23 in the X direction are arc-shaped edges 23a and 23b, respectively. Therefore,
The light beam L6 has the arc-shaped edges 23a and 23b.
Is radiated on the reticle as light having a concentric two-dimensional illuminance distribution. Therefore, FIG.
Similar to the case of using the aperture of (1), if the reticle is moved in the Y direction, the unevenness of the illuminance of the light beam in the X direction is eliminated.

FIG. 4C shows a case where a triangular opening 24 is formed in the light shield plate 16. In FIG. 4C, the cylindrical lens 7 of FIG.
The light beam L6 emitted from A is irradiated. The left edge 24a and the right edge 24b of the opening 24 in the X direction open in a fan shape.
The width of the light beam L6 in the X direction is limited by a and 24b. The edges 24a and 24b intersect each other obliquely in the Y direction, and the light beam L6 is diffracted by the oblique edges 24a and 24b, and is irradiated onto the reticle as light having a rhombic two-dimensional illuminance distribution. To do. Therefore, as in the case of using the aperture of FIG. 1B, if the reticle is moved in the Y direction, the illuminance unevenness of the light beam in the X direction is eliminated.

Although the present invention is applied to the above-described embodiment when the light beam is incident on the object to be examined substantially vertically, the present invention can be applied to an oblique incidence system as shown in FIG. Needless to say. Even when the present invention is applied to the oblique incidence system as shown in FIG. 6, the direction of the illuminance unevenness of the light beam on the reticle is set in correspondence with the relative scanning direction,
In addition, by setting the relative moving speed of the reticle to a predetermined speed, it is possible to make the detection sensitivity of defects on the entire surface of the reticle uniform.

Further, not only the reticle but also the pellicle stretched on the reticle is inspected for defects,
The present invention can be applied. As described above, the present invention is not limited to the above-described embodiments, and various configurations can be taken without departing from the gist of the present invention.

[0037]

According to the present invention, the light beam irradiation area on the object can be limited to a desired area by the light shielding means. Furthermore, since the microscopic two-dimensional illuminance unevenness of the light beam on the object to be inspected, which is formed by the edge of the light shielding means, can be reduced by integrating in the scanning direction by the scanning means. There is an advantage that the detection sensitivity of the defects on the entire surface can be made uniform.

The shading means also has two substantially parallel edges facing each other for limiting the illuminated area from both sides in the direction in which the light beam is expanded, these two edges being relative to each other. If it is non-parallel to the scan direction,
Or the shading means has two opposed fan-shaped edges for limiting the illuminated area from both sides in the direction in which the light beam is expanded, each of these two edges being relative to each other. When it is not parallel to the direction of, the configuration is simple.

[Brief description of drawings]

1A is a perspective view showing an embodiment of a defect inspection apparatus according to the present invention, and FIG. 1B is a plan view showing a light shielding plate 16 in FIG. 1A.

2A is a diagram showing a kind of contour line of the illuminance distribution of the illumination area on the reticle in FIG. 1, and FIG. 2B is an illuminance distribution in the X direction at two cross sections of the illuminance distribution in FIG. 2A. FIG.

3A is a diagram showing a kind of more detailed contour line of the illuminance distribution of the illumination area on the reticle shown in FIG. 1, and FIG.
3A is a diagram showing an illuminance distribution in the X direction in two cross sections of the illuminance distribution in FIG. 3A, and FIG. 3C is a diagram showing an illuminance distribution in the Y direction in two cross sections in the illuminance distribution in FIG.

4 (a) to 4 (c) are respectively a light shielding plate 16 of the embodiment.
It is a top view which shows the modification of the opening formed above.

FIG. 5 is a perspective view showing an example of a conventional defect inspection apparatus.

FIG. 6 is a perspective view showing another example of a conventional defect inspection apparatus.

7A is a diagram showing an illuminance distribution in the Y direction of the illumination region 8 in FIG. 5, and FIG. 7B is a diagram showing an illuminance distribution in the X direction in the illumination region 8 in FIG.

FIG. 8 is a perspective view showing a case where the light beam is further expanded and an illumination area is limited by a light shielding plate in the defect inspection apparatus of FIG.

9 is a diagram showing an illuminance distribution in the X direction in an illumination area on the reticle shown in FIG.

[Explanation of reference symbols] 1 reticle 2 stage 3 driving device 4 length measuring device 5 light source 6A negative cylindrical lens 7A positive cylindrical lens 10 light receiving lens 11 one-dimensional image sensor 16 light-shielding plate 19, 22, 23, 24 aperture 20 Slit-shaped illumination area

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location // H01L 21/66 J 7630-4M

Claims (3)

[Claims] 1. A light source for generating a light beam, a light beam expanding means for expanding the light beam in a predetermined direction and irradiating the object with the light beam, and a light beam expanding direction for intersecting the expanded direction of the light beam. The light beam expanding unit has a scanning unit that relatively scans the test object, and a light receiving unit that photoelectrically converts scattered light generated from a defect on the test object, and is obtained by the light receiving unit. In an apparatus for inspecting the defect based on a photoelectric conversion signal, a light shield having a plurality of edges for limiting an illumination area irradiated by the light beam on the object to be inspected in a direction in which the light beam is expanded. A defect inspection apparatus comprising means for arranging at least one edge of the plurality of edges parallel to a direction intersecting the relative scanning direction. 2. The light blocking means has two substantially parallel edges facing each other for limiting the illumination area from both sides in a direction in which the light beam is expanded, and the two edges are relative to each other. The defect inspection apparatus according to claim 1, wherein the defect inspection apparatus is substantially parallel to a direction intersecting the scanning direction. 3. The light shielding means has two fan-shaped edges facing each other for limiting the illumination area from both sides in the direction in which the light beam is expanded, and the two edges are respectively the above-mentioned edges. The defect inspection apparatus according to claim 1, wherein the defect inspection apparatus is parallel to a direction intersecting a relative scanning direction.