JPH09281049A - Defect inspection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a defect inspection apparatus by which the reliability of the defect inspection of a pellicle frame can be enhanced. SOLUTION: A light irradiation means 11 and a light receiving means 11 are held in a constant positional relationship by a movement means 12. While they are being moved relatively with reference to a pellicle frame 2, the pellicle frame 2 is irradiated with light by the light irradiation means 11 from the side of an upper edge on which a pellicle 1 at the pellicle frame 2 is installed so as to be stretched or from the side of a lower edge faced with the upper edge. Reflected light obtained when the pellicle frame 2 is irradiated with the light is received by the light receiving means 11. On the basis of the output of the light receiving means 11, whether the defect of the pellicle frame 2 exists or not is discriminated. Thereby, it is possible to realize a defect inspection apparatus 10 by which the defect inspection of the pellicle frame 2 can be performed with high accuracy and in a short time and which can enhance the reliability of the defect inspection of the pellicle frame 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defect inspection apparatus, and is particularly suitable for application to a defect inspection apparatus for inspecting defects of a pellicle frame mounted on a photomask used in a semiconductor exposure process.

[0002]

2. Description of the Related Art Conventionally, in a photolithography process, which is one of manufacturing processes of integrated circuits, when a circuit pattern formed on a photomask is transferred onto a substrate to be exposed by using an exposure device, dust or the like is caused on the photomask. In order to prevent foreign matter from adhering to the photomask, there is a photomask whose surface is covered with a light-transmitting thin film (foreign matter adhesion preventing film) having a thickness of several [μm] called a pellicle.

As shown in FIG. 9, a pellicle 1 is stretched on a support frame 2 (hereinafter referred to as a pellicle frame) 2 made of aluminum or diuralumin, and the pellicle frame 2 and a photomask 3 are in the form of an adhesive tape. Adhesive 4
(Thickness 0.1 [mm] to 1 [mm])
By mounting the photomask 3 so as to cover the surface thereof, it is possible to prevent foreign substances from directly adhering to the photomask 3.

The shape of the pellicle frame 2 is as follows.
In addition to the square shape as shown in FIG. 9, there are a rectangular shape, a circular shape, and a rectangular shape in which four corners are formed in an arc shape. Generally, the pellicle frame 2 has a thickness of 2 to 3 [mm] and a height of It is selected to have a predetermined size of 3 to 6 [mm]. FIG.
As shown in 0, normally, the lower end surface 2 of the pellicle frame 2 is
A is coated with an adhesive 4 for adhering to the photo mask 3, and each edge 2B, 2 is provided to prevent dust generation.
C, 2D and 2E are chamfered by about 0.2 to 0.4 [mm].

Further, since the pellicle frame 2 is formed by shaving, the surface of the pellicle frame 2 is left with a shaving 2F, which is after the blade of the cutter when processed by a milling machine, and the surface is exposed. It is processed to be almost black in order to reduce irregular reflection of light. Depending on the type of pellicle frame 2, pellicle frame 2
There is a case where the adhesive 6 is thinly applied to the inner wall surface 2G so that the foreign matter 5 attached to the inner wall surface 2G does not drop.

[0006]

Even if the pellicle 1 prevents the foreign matter 5 from adhering to the photomask 3, the foreign matter 5 may still adhere to the photomask 3. For example, when foreign matter adhering to the front surface (outer surface) of the pellicle 1 is purged by air blow, the foreign matter adhering to the back surface (inner surface) of the pellicle 1 is filtered off by the vibration of the pellicle 1 onto the surface of the photomask 3. In addition, the foreign matter 5 attached to the inner wall surface 2G of the pellicle frame 2 may fall on the photomask 3 and attach to the photomask 3.

Therefore, before mounting the pellicle frame 2 on the photomask 3, it is necessary to inspect whether or not foreign matter is attached to the front and back surfaces of the pellicle 1 and especially to the inner wall surface 2G of the pellicle frame 2. However, at present, there are inspected and commercially available inspection devices for inspecting whether or not foreign matter is attached to the pellicle 1. However, in order to inspect whether or not the pellicle frame 2 has a defect such as foreign matter. There is no inspection device, and the inspector visually inspected the pellicle frame 2.

As described above, depending on the type of the pellicle frame 2, there is a pellicle frame 2 on which the adhesive 6 is applied to the inner wall surface 2G, and in the case of such a pellicle frame 2, the inner wall surface 2G. Depending on how the light is applied to the 2G, the scattered light of the adhesive 6 may be noticeable and it may be difficult to detect the foreign matter 5, or the foreign matter 5 may be missed depending on the direction in which the inspector looks at the pellicle frame 2. However, there is a problem that the inspection accuracy varies. Further, the inspection accuracy varies depending on the skill of the inspector, and further, there is a problem that a large amount of time is required for the inspection due to the visual inspection. Therefore, the inspection method of the pellicle frame 2 is still insufficient.

The present invention has been made in consideration of the above points, and an object thereof is to propose a defect inspection apparatus capable of improving the reliability of defect inspection of a pellicle frame.

[0010]

In order to solve such a problem, in the first invention, a pellicle frame (2) is stretched with a pellicle (1) for dust-proofing a mask or reticle.
In the defect inspection device (10) for inspecting defects of (1), the pellicle frame (2) has an upper end surface (2H) side on which the pellicle (1) is stretched, or a lower end surface (2A) side facing the upper end surface (2H). From the pellicle frame (2) to the light (L
Light irradiating means (11 for irradiating ₁ , L ₂ , L ₃ , L ₄ )
A, 11B ₁ , 11B ₂ , 11C ₁ , 11C ₂ , 11D
₁ , 11D ₂ , 21A ₁ , 21A ₂ ) and the reflected light (L ₅ , obtained by irradiating the pellicle frame (2) with light.
L ₆ ) light receiving means (11E, 11F, 11G,
21B, 21C, 21D) and light irradiation means (11A, 1C).
1B ₁ , 11B ₂ , 11C ₁ , 11C ₂ , 11D ₁ , 1
1D ₂ , 21A ₁ , 21A ₂ ) and light receiving means (11E,
11F, 11G, 21B, 21C, 21D) in a fixed positional relationship, the light irradiation means (11A, 11B ₁ , 11B ₂ , 11C ₁ ,
11C ₂ , 11D ₁ , 11D ₂ , 21A ₁ , 21A ₂ )
And light receiving means (11E, 11F, 11G, 21B, 21
Moving means (12) for relatively moving C, 21D) and light receiving means (11E, 11F, 11G, 21B, 21C, 2
Defect determining means (11H, 21E) for determining the presence or absence of a defect in the pellicle frame (2) based on the output of 1D).

As described above, the light irradiation means (11A, 11B)
₁ , 11B ₂ , 11C ₁ , 11C ₂ , 11D ₁ , 11D
₂ , 21A ₁ , 21A ₂ ) and light receiving means (11E, 11)
F, 11G, 21B, 21C, 21D) the moving means (1
The upper end surface (2H) on which the pellicle (1) of the pellicle frame (2) is stretched while being held in a fixed positional relationship by means of 2) and moving relative to the pellicle frame (2).
Side or the lower end surface (2A) side facing the upper end surface (2H), the pellicle frame (2) is irradiated with light from the light irradiation means, and the reflected light obtained by irradiating the pellicle frame with light is received. (11A, 11B ₁ , 11B ₂ , 11
C ₁ , 11C ₂ , 11D ₁ , 11D ₂ , 21A ₁ , 21
A ₂ ) receives light, and the light receiving means (11A, 11B ₁ , 11
B ₂ , 11C ₁ , 11C ₂ , 11D ₁ , 11D ₂ , 21
By determining whether or not there is a defect in the pellicle frame (2) based on the output of A ₁ , 21A ₂ ),
The defect inspection of the pellicle frame (2) can be performed with high accuracy and in a short time.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

(1) Overall Structure In FIG. 1 in which parts corresponding to those in FIG. 9 and FIG. 10 are assigned the same reference numerals, numeral 10 generally indicates a defect inspection apparatus according to an embodiment of the present invention. Is composed of a defect detection unit 11 and a drive unit 12 that drives the defect detection unit 11, and is arranged on the inner wall surface 2G side of the pellicle frame 2 on which the pellicle 1 is stretched. The defect detection unit 11 irradiates the inner wall surface 2G, or the inner wall surface 2G and the upper end surface 2H of the pellicle frame 2 with white light so that the inner wall surface 2G or the inner wall surface 2G, as will be described later.
The presence or absence of foreign matter in the pellicle frame 2 is inspected based on the scattered light generated on the upper end surface 2H.

The drive unit 12 includes an x-axis direction drive member 12A,
It is composed of a y-axis direction driving member 12B and a rotation direction driving member 12C. The x-axis direction driving member 12A is configured to be movable in the x direction and a direction opposite to the x direction based on the drive control of a driving motor (not shown), and along the y axis direction driving member 12B. It can move in the y-axis direction and in the direction opposite to the y-axis direction.

The rotation direction driving member 12C includes a shaft 12C ₁ provided on the lower surface of the x-axis direction driving member 12A, and the shaft 12C.
Rotating part 12C ₂ provided at the other end of ₁ and rotating part 12C
₂ is provided so as to be substantially perpendicular to the shaft 12C ₁ and is constituted by a shaft 12C ₃ attached to the defect detection unit 11. The rotator 12C ₂ is designed to be rotatable in the direction indicated by θ in the figure based on the drive control of a drive motor (not shown), so that the defect detecting unit 11 can be rotated in the θ direction. Has been done.

In practice, in this embodiment, the defect detection unit 11 includes a one-dimensional CCD (Charge Coupled Device) which will be described later and is housed inside the defect detection unit 11.
2) while keeping the horizontal distance from the inner wall surface 2G (not shown) at a constant distance ΔR and the height from the upper end surface 2H of the pellicle frame 2 at a predetermined distance.
It moves along the inner wall surface 2G of the pellicle frame 2 along a locus as shown in FIG.

In other words, the defect detection unit 11 first moves from the inspection starting point A to the point B (inner wall surface 2G ₁ ) to the inner wall surface 2G.
From the point B to the point C on the straight line AB, while moving from the point C to the point D in an arc shape while keeping the distance ΔR from the inner wall surface 2G. Inspect the corner section 2G _A of. After that, the defect detection unit 11 moves from the point D to the point E, and then moves from the point E through the point D to the point F (inner wall surface 2G ₂ ) while maintaining the distance ΔR from the inner wall surface 2G. .

Subsequently, the defect detection unit 11 returns from the point F to the point G on the straight line EF, and the distance Δ from the inner wall surface 2G.
Go to arcuate while retaining the R from the point G to the point H to check the corner 2G _B. After this, the defect detection unit 1
After moving from the point H to the point I, 1 moves from the point I through the point H to the point J (inner wall surface 2G ₃ ) while maintaining the distance ΔR from the inner wall surface 2G.

After that, after similarly moving in an arc from the point K to the point L and inspecting the corner portion 2G _C , from the point M to the point L to the point N (the inner wall surface 2G ₄ ) from the inner wall surface 2G. Of the inner wall surface 2G, the corner portion 2G ₄ is inspected by moving in an arc shape from the point O to the point P while maintaining the distance ΔR. Here, from corner 2G _A to corner 2G
When inspecting _D , the x-axis direction driving member 11A, the y-axis direction driving member 11B, and the rotation direction driving member 11C are simultaneously driven.

Therefore, the defect detection unit 11 is moved along the inner wall surface 2G of the pellicle frame 2 based on the drive control of the x-axis direction driving member 12A, the y-axis direction driving member 12B and / or the rotation direction driving member 12C. It can move relative to the pellicle frame 2 while holding ΔR.

(2) Structure of Defect Detection Unit According to First Embodiment Here, the structure of the defect detection unit 11 according to the first embodiment is shown in FIG. 3 in which parts corresponding to those in FIG. In this defect detection unit 11, the lamp house 11A
The white light emitted from the optical fiber is the optical fiber 11B ₁ and 11B.
White light L ₁ and L ₂ are emitted from the bases 11C ₁ and 11C ₂ through B ₂ , respectively. This base 11C ₁
And white light L ₁ and L emitted from 11C ₂ respectively
After entering the mirrors 11D ₁ and 11D ₂ respectively, ₂ is irradiated to almost the same irradiation position P on the inner wall surface 2G of the pellicle frame 2 by the mirrors 11D ₁ and 11D ₂ .

As shown in FIG. 4, the defect detecting unit 11 has white light L ₁ and L ₂ for the inner wall surface 2G.
Are radiated from two different directions that are substantially symmetrical with respect to the irradiation position P, and the white lights L ₁ and L ₂ incident on the irradiation position P are scattered lights among the scattered lights generated at the irradiation position P. L ₃ is received by mirror 11E, which is arranged approximately in the center between mirrors 11D ₁ and 11D ₂ in the yz plane.

The defect detection unit 11 guides the scattered light L ₃ incident on the mirror 11E to the light receiving lens 11F and collects it. Then, the image is received by, for example, a one-dimensional CCD 11G. The CCD 11G is arranged in the xz plane or in the vicinity of the xz plane, and is arranged so that the CCD 11G and the irradiation position P are in a conjugate relationship, and the CCD 11G is always conjugated with the irradiation position P even when the defect detection unit 11 moves. The distance ΔR from the inner wall surface 2G is maintained so as to be in a relationship.
The CCD 11G is arranged so that an image can be formed in the height direction (z direction) of the inner wall surface 2G.

Here, the incident angles α (α ₁ and α ₂ ) and β of the white lights L ₁ and L ₂ with respect to the inner wall surface 2G and the inner wall surface 2G
The arrangement position of the mirror 11E with respect to will be described. In this defect inspection device 10, as shown in FIG.
The inclination angle β of ₁ and L ₂ in the x-axis plane in the xz plane (that is, the inner wall surface 2G) is set to 0 to 20 °,
Of the scattered light reflected by the inner wall surface 2G, the reflection angle γ is 60 ° to 90
The mirror 11E is arranged so that the scattered light L ₃ of 90 ° can enter.

That is, the scraped 2F and the adhesive 6 existing on the pellicle frame 2 have a small step with the inner wall surface 2G, while the portion to which the foreign matter 5 adheres has a convex shape.
The step between the foreign material 5 and the inner wall surface 2G is scraped off, and then the second surface 2F and the adhesive 6
Is larger than the step with the inner wall surface 2G. Therefore, only 2 left
By setting the inclination angle β (β = 0 to 20 °) so that the scattered light from F or the adhesive 6 and the scattered light from the foreign matter 5 can be discriminated, the scattered light from the 2F after cutting and the adhesive 6 is conspicuous. It can be lost. 2F and 6 adhesive after scraping
Since the scattered light due to is strong in the opposite direction of the specular reflection of light, the scattered light generated on the inner wall surface 2G can be discriminated from the scattered light from the 2F or the adhesive 6 and the scattered light from the foreign matter 5 after shaving. reflection angle in among the wall 2G gamma are arranged mirror 11E in a position as may be incident scattered light L ₃ of 60 ° to 90 °.

Here, as shown in FIG. 6, for example, most of the scattered light generated from the ridge 2B spreads in the vicinity of the xz plane, so the scattered light from the ridge 2B is incident on the CCD 11G, but as described above. The white lights L ₁ and L ₂ are inclined to the x-axis direction in the xz plane by an angle β and the inner wall surface 2
Since it is incident on G, it is possible to prevent the scattered light from each of the edges 2B, 2C, 2D and 2E from entering the CCD 11G.

Further, in this defect inspection apparatus 10, as shown in FIG. 4, the white lights L ₁ and L ₂ emitted from the bases 11C ₁ and 11C ₂ are directed in two different directions which are substantially symmetrical with respect to the irradiation position P. From the white light L ₁ and L
_The incident angles α ₁ and α _{2 of 2 with} respect to the xy plane (that is, the incident angle in the height direction with respect to the inner wall surface 2G) are approximately −
It is set to 10 ° to -60 ° and 10 ° to 60 °.

That is, as described above, the pellicle frame 2
Since each of the ridges 2B, 2C, 2D and 2E is chamfered, in order to reduce the scattered light from the chamfered portion of each of the ridges 2B, 2C, 2D and 2E, the white light L ₁ and L ₂ with respect to the xy plane is reduced. Incident angles α ₁ and α ₂ are approximately -10 ° ~
It is set to -60 ° and 10 ° to 60 °. As a result, it is possible to reduce the reception of scattered light from the chamfered portion when the white light L ₁ and L ₂ is applied to the inner wall surface 2G, and to easily distinguish the scattered light from the foreign matter 5.

As described above, in the defect inspection apparatus 10,
The inclination angle β of the white light L ₁ and L ₂ with respect to the inner wall surface 23G in the xz plane in the xz plane is set to 0 to 20 °, and the reflection angle γ of the scattered light reflected by the inner wall surface 2G is 60. ° ~ 90 °
The mirror 11E is arranged so that the scattered light L ₃ of the white light L ₁ and L ₂ is incident on the xy plane and the incident angle α ₁
By setting α ₂ and α ₂ to −10 ° to −60 ° and 10 ° to 60 °, respectively, it is possible to substantially avoid the reception of the scattered light by the 2F or the adhesive 6 and the scattered light from the chamfered portion after cutting. Therefore, only the light scattered by the foreign matter 5 is transferred to the CCD.
The image can be received by 11G.

The CCD 11G converts the scattered light L ₃ that has been imaged and received into an electric signal S1 and then sends this electric signal S1 to the defect discriminating section 11H. The defect discrimination unit 11H is the CCD 11
When the electrical signal S1 sent from G is binarized at a slice level predetermined according to the size of the back ground noise and the size of the foreign matter 5 to be detected, and the electrical signal S1 above the slice level is obtained, It is determined that the foreign matter 5 is attached to the inner wall surface 2G.

(3) Operation and effect of the embodiment With the above configuration, the defect inspection apparatus 10 outputs the white lights L ₁ and L ₂ from the defect detection unit 11 to α ₁ respectively.
= -10 ° to -60 °, α ₂ = 10 ° to 60 ° and β = 0 ° to 20
While irradiating the inner wall 2G at an incident angle of °, as shown in FIG. 2, in order inner wall 2G ₁ defect detection Yunitsuto 11, corners 2G _A, the inner wall surface 2G _2, corner portions 2G _B, the inner wall surface 2
G ₃ , corner portion 2G _C , inner wall surface 2G ₄ and corner portion 2G
_The foreign object 5 existing on the inner wall surface 2G is detected by moving along _D. In this case, the defect detection unit 11 has the inner wall surface 2G
While circling around, the white light emitted from the house lamp 11A is branched by the optical fibers 11B ₁ and 11B ₂ and is applied to the inner wall surface 2G as white light L ₁ and L ₂ .

Here, when inspecting the inner wall surface 2G, if the light of both the white light L ₁ and L ₂ is always inspected, for example, when inspecting the inner wall surface 2G ₂ , a predetermined part of the latter half portion on the straight line EF is determined. From the position, the pellicle frame 2 is attached to the wall, and the white light L ₂ is not emitted to the inner wall surface 2G ₂ . In order to avoid this, in the defect inspection apparatus 10, as shown in FIG.
Move between straight lines AB, EF, IJ, and MN to move the inner wall surface 2G
_When inspecting ₁ , 2G ₂ , 2G ₃ and 2G ₄ , white light L ₂ is received up to the first half between the straight lines AB, EF, IJ and MN.
Only the white light L ₁ is irradiated to the latter half of the straight lines AB, EF, IJ, and MN.

For example, in the case of the straight line EF, from the point E to the straight line E
It is controlled so that only the white light L ₂ is emitted to the intermediate point Q between F and only the white light L ₁ is emitted from the intermediate point Q to the point F. As a result, since the same amount of light can be constantly applied to the inner wall surface 2G, the foreign matter 5 attached to the inner wall surface 2G
Can be accurately detected.

Of the scattered light generated on the inner wall surface 2G, the scattered light L ₃ is incident on the mirror 11E and then the light receiving lens 11F.
Is guided to and condensed to form an image on the CCD 11G.
The CCD 11G converts this image forming light into an electric signal S1 and sends it to the defect discriminating section 2H, which in turn outputs the electric signal S1.
Is above the slice level, and if above the slice level, it is determined that the foreign matter 5 is attached to the inner wall surface 2G.

Therefore, in the defect inspection apparatus 10, since the scattered light from the foreign material 5 can be focused and received on the CCD 11G by substantially avoiding the scattered light from being cut off by the 2F or the adhesive agent 6, it is possible to perform the conventional operation. The inspection accuracy can be significantly improved as compared with the visual inspection. Further, in this defect inspection apparatus 10, the defect inspection unit 11 is circulated while irradiating the inner wall surface 2G with the white light L ₁ and L ₂ from the defect inspection unit 11, so that it is possible to compare with the conventional visual inspection. Therefore, the inspection time can be significantly reduced.

According to the above configuration, the defect detection unit 1
1 is circulated on the inner circumference of the pellicle frame 2 by the driving unit 12, and at the same time, the white light L ₁ and L ₂ is inclined at an inclination angle β in the x-axis direction of 0 to 20 ° with respect to the xy plane. The incident angles α ₁ and α ₂ are made to fall on the inner wall surface 2G at −10 ° to −60 ° and 10 ° to 60 °, respectively.
Of the scattered light generated in G, the scattered light L ₃ having a reflection angle γ of 60 ° to 90 ° is C through the mirror 11E and the light receiving lens 11F.
The image is received by the CD 11G, and the output signal S of the CCD 11G is received.
By determining that the foreign matter 5 is attached to the inner wall surface 2G when 1 is equal to or higher than the slice level,
Since the scattered light from the foreign matter 5 can be imaged and received on the CCD 11G by substantially avoiding the reception of the scattered light by the 2F or the adhesive 6 after the shaving, the inspection accuracy is remarkably higher than that of the conventional visual inspection. Therefore, it is possible to realize the defect inspection apparatus which can improve the reliability of the defect inspection of the pellicle frame 2.

(4) Structure of Defect Detection Unit According to Second Embodiment In FIG. 7 in which parts corresponding to those in FIG. 3 are denoted by the same reference numerals, 21 indicates the defect detection unit according to the second embodiment of the present invention as a whole. As shown, the defect detection unit 21 can inspect the foreign matter 5 existing on the upper end surface 2H in addition to the inner wall surface 2G of the pellicle frame 2.

In other words, in the defect detection unit 21, the lamp fiber 11A (not shown) is connected to the optical fiber 1.
1B ₁ and 11B ₂ (not shown) through the base 11C ₁
And white light L ₁ and L ₂ (not shown) emitted from 11C ₂ (not shown) are magnified by the lens groups 21A ₁ and 21A ₂ (not shown), respectively, inside the pellicle frame 2. The wall surface 2G and the upper end surface 2H are irradiated. Here, the lens groups 21A ₁ and 21A
₂ white light L ₃ and L ₄ magnified by (not shown)
The irradiation angles α (α ₁ , α ₂ ) and β (not shown) are the same as those in the defect detection unit 11, and the reflection angle γ of the scattered light reflected by the inner wall surface 2G is 60 ° to 90 °. Scattered light L ₅
Is incident on the mirror 11E.

On the other hand, of the scattered light reflected by the upper end surface 2H of the pellicle frame 2, the scattered light L having a reflection angle δ of 5 ° to 30 °.
_The mirror 21B is arranged so that ₆ can be incident.
Here, the pellicle 1 is attached to the upper end surface 2H of the pellicle frame 2.
The outermost surface of the upper end surface 2H is the pellicle 1
Therefore, the scraped upper end surface 2H (not shown) exists below the pellicle 1.

In this case, the white light L _{3 with} respect to the upper end surface 2H is
Even if the incident angles α (α ₁ , α ₂ ) and β of L ₄ and L ₄ are incident at the same angle as in the defect detection unit 11, the reflection angle δ
By making the scattered light L ₆ of 5 ° to 30 ° incident on the mirror 21B, it is possible to substantially avoid the reception of the scattered light due to the scraping of the upper end surface 2H. The scattered light due to and the scattered light due to the foreign matter 5 can be easily discriminated.

The scattered light L ₆ incident on the mirror 21B is condensed by the light receiving lens 21C, and then is arranged in a conjugate relationship with the upper end surface 2H, and is arranged substantially in the xz plane.
The image is received at. The CCD 21D converts the image forming light into an electric signal S.
After being converted into 2, the electric signal S2 is converted into the defect discrimination section 21E.
To send to. The defect discriminator 21E binarizes the electric signal S2 sent from the CCD 21D at a predetermined slice level according to the size of the background noise and the size of the foreign matter 5 to be detected, and the electric signal S2 above the slice level. If it is obtained, it is determined that the foreign matter is attached to the upper end surface 2H. The inner wall surface 2G is determined in the same manner as in the defect detection unit 11 described above.

In the above structure, the defect detection unit 2
The same incidence angle α (α _1, α ₂₎ in the case of the white light L ₃ and L _4, respectively from 1 defect detection Yunitsuto 11 and while irradiating the inner wall surface 2G and the upper end surface 2H in beta, defect detection Yunitsuto 21 Is circulated along the inner circumference of the pellicle frame 2 to detect foreign matter present on the inner wall surface 2G and the upper end surface 2H.

In this case, of the scattered light generated on the upper end surface 2H, the scattered light L ₆ is imaged and received by the CCD 21D via the mirror 21B and the light receiving lens 21C, and the inner wall surface 2
Of the scattered light generated by G, the scattered light L ₅ is imaged and received by the CCD 11G via the mirror 11E and the light receiving lens 11F. The defect detection unit 21E determines that the foreign matter 5 is attached to the upper end surface 2H when the output signal S2 from the CCD 21D is equal to or higher than the slice level.
When the output signal S1 from D11G is equal to or higher than the slice level, it is determined that the foreign matter 5 is attached to the inner wall surface 2G. Therefore, in this defect inspection apparatus 10, scattered light due to foreign matter on the inner wall surface 2G and the upper end surface 2H of the pellicle frame 2 is imaged on the CCD 11G and CCD 21D, respectively, by substantially avoiding reception of scattered light by the scraped 2F and the adhesive 6. Can receive light.

According to the above configuration, the defect detection unit 2
1 is circulated along the inner circumference of the pellicle frame 2 by the driving unit 12, and at the same time, the white lights L ₃ and L ₄ are generated by xz
The inclination angle β in the plane to the x-axis direction is 0 to 20 °, xy
The incident angles α ₁ and α ₂ with respect to the plane are −10 ° to −, respectively.
The scattered light L ₅ having a reflection angle γ of 60 ° to 90 °, which is incident on the inner wall surface 2G and the upper end surface 2H at 60 ° and 10 ° to 60 ° and is generated on the inner wall surface 2G, is reflected by the mirror 11E and the mirror 11E. The image is formed and received by the CCD 11G through the light receiving lens 11F, and C
When the output signal S1 of the CD 11G is equal to or higher than the slice level, it is determined that the foreign matter 5 is attached to the inner wall surface 2G, and the reflection angle δ of the scattered light generated on the upper end surface 2H is 5 ° to 30 °.
The scattered light L _{6 of} is imaged and received by the CCD 21D via the mirror 21B and the light receiving lens 21C, and when the output signal S2 of the CCD 21D is above the slice level, the upper end surface 2
Since it is determined that the foreign matter adheres to H, the scattered light caused by the foreign matter on the inner wall surface 2G and the upper end surface 2H of the pellicle frame 2 is substantially avoided by avoiding the reception of the scattered light by the scraped 2F and the adhesive 6. And CCD2
It is possible to realize a defect inspection device capable of forming an image and receiving light in 1D and thus inspecting the inner wall surface 2G and the upper end surface 2H of the pellicle frame 2 simultaneously and accurately.

(4) Other Embodiments In the above embodiment, the case where the defect inspection apparatus 10 is arranged on the side of the pellicle frame 2 on which the pellicle 1 is stretched has been described, but the present invention is not limited to this. Instead, the defect inspection apparatus 10 may be arranged on the side of the pellicle frame 2 to which the adhesive 4 is applied (that is, the lower end surface 2A side). Incidentally, the pellicle frame 2 is normally housed in the pellicle case with the pellicle 1 facing upward. Therefore, by opening the lid of the pellicle case and setting the defect inspection apparatus 10, the pellicle frame 2 can be inspected without holding the pellicle frame 2.

However, when performing a defect inspection on the pellicle frame 2 before taking out the pellicle frame 2 from the pellicle case and adhering and fixing the pellicle frame 2 to the photomask, the pellicle frame 2 is turned upside down so that the defect inspection apparatus 10 operates. In some cases, the arrangement cannot be arranged as in the above-described embodiment. Therefore, if the defect inspection apparatus 10 can be arranged on the lower end surface 2A side of the pellicle frame 2, such a case can be dealt with.

In the above embodiment, the presence or absence of the foreign matter 5 on the inner wall surface 2G and the upper end surface 2H of the pellicle frame 2 is determined based on a predetermined slice level, but the present invention is not limited to this. Not limited to this,
The output signals S1 and S2 of the CCDs 11G and 21D are input to the monitor, the images of the inner wall surface 2G and the upper end surface 2H are displayed on the monitor, and the inspector determines the presence / absence of foreign matter by looking at the image displayed on the monitor. You may do it. In this case, the horizontal direction of the monitor is the output of the CCD 11G (that corresponds to the z direction of the inner wall surface 2G) and the vertical direction of the monitor is the output of the entire circumference of the pellicle frame 2 (that is, the circumferential direction of the inner wall surface 2G). For example, since the inspection result for one round of the inner wall surface 2G can be displayed on the monitor 1 screen, the inner wall surface 2G can be inspected easily and in a short time.

Further, in the above embodiment, the CCD 1
The case where the 1G and 21D and the defect determining sections 11H and 21E are provided on the side of the pellicle frame 2 on which the pellicle 1 is stretched has been described, but the present invention is not limited to this, and the adhesive 4 of the pellicle frame 2 is applied. You may make it provide in the side (namely, lower end surface 2A side). Further, in the above-mentioned embodiment, x of white light L ₁ and L ₂ , L ₃ and L ₄
The case where the inclination angle β in the x-axis direction in the z plane is set in the range of 0 to 20 ° has been described, but the present invention is not limited to this, and the inclination angle β is set in the range of 0 to 45 °. In essence, the tilt angle β may be set to another range as long as it is possible to discriminate the light scattered by the scraped material 6 or the adhesive 2F from the light scattered by the foreign matter 5.

Further, in the above embodiment, the inner wall surface 2
The case where the mirror 11E is arranged so that the scattered light L ₃ having a reflection angle γ of 60 ° to 90 ° among the scattered light generated in G can be incident has been described, but the present invention is not limited to this, and the reflection angle γ is not limited thereto. But
The mirror 11 so that scattered light L ₃ of 30 ° to 90 ° can enter
E may be arranged. In short, if the scattered light due to the 2F or the adhesive 6 and the scattered light due to the foreign matter 5 can be discriminated after cutting, the scattered light L ₃ reflected at various other reflection angles γ is incident. The mirror 11E may be arranged so as to be able to do so.

Further, in the above-mentioned embodiment, the mirror 21B is arranged so that the scattered light L ₆ having the reflection angle δ of 5 ° to 30 ° among the scattered light generated on the upper end surface 2H of the pellicle frame 2 can enter. Although the case has been described, the present invention is not limited to this, and in short, various other various methods may be used as long as the reception of scattered light due to shaving on the upper end surface 2H can be avoided to the extent that it can be discriminated from the scattered light due to the foreign matter 5. Scattered light L reflected at reflection angle δ
The mirror 21B may be arranged so that 6 can be incident.

Furthermore, in the above-described embodiment, the case where the pellicle frame 2 is irradiated with white light from the house lamp 11A has been described, but the present invention is not limited to this.
The pellicle frame 2 may be irradiated with monochromatic light from a laser diode, a light emitting diode or the like. When using a laser diode or a light emitting diode, it is necessary to pay attention to the values of the incident angle α (α ₁ , α ₂ ) and the light receiving angle γ. That is, since the pellicle 1 is a thin film, the transmittance of monochromatic light may change depending on the incident angle α, and the transmittance may decrease depending on the values of the incident angle α and the light receiving angle γ. This is because the wavelength and the incident angle differ depending on the type of the pellicle 1.

On the other hand, in the case of white light, since the wavelength is wide, its transmittance does not drop as much as that at a certain incident angle in monochromatic light, so that the inspection accuracy is not affected.
However, when the mirror 11E is arranged at a position where scattered light whose acceptance angle γ exceeds 90 ° is incident on the scattered light reflected by the inner wall surface 2G, the pellicle 1 has white light transmittance. Even if it is lowered, the inspection accuracy is lowered.

Further, in the above-mentioned embodiment, the case of inspecting the square pellicle frame 2 as the pellicle frame 2 has been described, but the present invention is not limited to this, and as shown in FIG. 8, a circular pellicle frame 2 is inspected. Other shapes of pellicle frames, such as 30 and rectangular pellicle frames, can also be inspected. In the case of the pellicle frame 30, the x-axis direction driving member 12A, the y-axis direction driving member 12B, and the rotation are arranged so that the defect detection units 11 and 21 always face the inner wall surface 2G side while maintaining the distance ΔR from the inner wall surface 2G. The direction drive member 12C is controlled.

Further, in the above-described embodiment, when inspecting the corner portions 2G _{A to} 2G _D of the pellicle frame 2, the defect detection units 11 and 21 are moved in an arc shape while maintaining the distance ΔR from the inner wall surface 2G. However, the present invention is not limited to this, and the pellicle frame 2 is usually used.
The radius of the circular arc of corners 2G _{A to} 2G _D is 3 to 5 [mm]
Since it is small, the defect detection units 11 and 21 are formed in an arc shape.
If the straight lines AB, EF, IJ, and MN are lengthened even without moving, the corners 2G _A to 2G _D can be inspected, and the movement of the drive unit 12 can be simplified. In this case, it is necessary to secure the depth of focus of the light receiving lens 11E.

Further, in the above-described embodiment, the inner wall surface 2G or the inner wall surface 2G and the upper end surface 2H of the pellicle frame 2 are used.
However, the present invention is not limited to this, and the periphery of the outer wall surface corresponding to the inner wall surface 2G of the pellicle frame 2 may be inspected. Further, in the above-described embodiment, as the defect inspection of the pellicle frame 2, the case of inspecting whether or not the foreign matter 5 is attached to the inner wall surface 2G or the inner wall surface 2G and the upper end surface 2H of the pellicle frame 2 is described. The present invention is not limited to this, and can be applied as a defect inspection of the pellicle frame 2 when inspecting various other defects such as foreign substances.

Further, in the above-described embodiment, the inner wall surface 2G or the inner wall surface 2G and the upper end surface 2H of the pellicle frame 2 are used.
When inspecting, always white light L ₁ and L ₂ or white light L ₃
2 and L ₄ are irradiated, the present invention is not limited to this, and in FIG. 2, between points B and C, between points D and E, between points F and G, between points H and I. The white light L ₁ and L ₂ or the white light L ₃ and L ₄ may not be emitted between the points J and K, between the points L and M, and between the points N and O. Further, in the above embodiment, the one-dimensional CCD
The case of using the 11G and the CCD 21D has been described, but the present invention is not limited to this, and a two-dimensional CCD may be used.

Further, in the above-described embodiment, the house lamp 11A is used as the light irradiating means for irradiating the pellicle frame with light from the upper end surface of the pellicle frame on which the pellicle is stretched or the lower end surface facing the upper end surface. Fibers 11B ₁ and 11B ₂ , bases 11C ₁ and 11C ₂ , mirrors 11D ₁ and 11D ₂ or house lamp 11A,
Optical fibers 11B ₁ and 11B ₂ , bases 11C ₁ and 1
1C ₂ , lens groups 21A ₁ and 21A ₂ , mirror 11D
_The case of using ₁ and 11D ₂ has been described, but the present invention is not limited to this, and various other light irradiation means can be applied as the light irradiation means.

Further, in the above-described embodiment, the mirror 11E, the light receiving lens 11F and the CCD are used as the light receiving means for receiving the scattered light obtained by irradiating the pellicle frame with light.
11G or mirror 11E, light receiving lens 11F and CC
D11G, mirror 21B, light receiving lens 21C and CC
Although the case of using D21D has been described, the present invention is not limited to this, and various other light receiving means can be applied as a light receiving means for receiving scattered light obtained by irradiating the pellicle frame 2 with light.

Further, in the above-mentioned embodiment, the drive section 12 is used as a moving means for moving the light emitting means and the light receiving means relative to the pellicle frame while maintaining the light emitting means and the light receiving means in a fixed positional relationship. Although the case of use is described, the present invention is not limited to this, and various other moving means can be applied as the moving means. Further, in the above-described embodiment, the case where the defect discriminating unit 11H or the defect discriminating units 11E and 21E is used as the defect discriminating unit for discriminating the presence or absence of the defect of the pellicle frame based on the output of the light receiving unit has been described. The invention is not limited to this, and various other discrimination means can be applied as the defect discrimination means.

[0060]

As described above, according to the present invention, the light irradiating means and the light receiving means are held in a fixed positional relationship by the moving means and relatively moved with respect to the pellicle frame,
Light is emitted from the light irradiating means to the pellicle frame from the upper end surface side where the pellicle of the pellicle frame is stretched or the lower end surface side opposite to the upper end surface, and the reflected light obtained by irradiating the pellicle frame with the light is obtained. By receiving light by the light receiving means and determining whether or not there is a defect in the pellicle frame based on the output of the light receiving means, it is possible to perform defect inspection of the pellicle frame with high accuracy and in a short time. A defect inspection apparatus capable of improving the reliability of defect inspection can be realized.

[Brief description of drawings]

FIG. 1 is a perspective view showing an overall configuration of a defect inspection apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic diagram for explaining a movement locus of a defect detection unit.

FIG. 3 is a schematic perspective view showing the structure of a defect detection unit according to the first embodiment.

FIG. 4 is a schematic front view showing the structure of a defect detection unit according to the first embodiment.

FIG. 5 is a schematic side view showing the structure of a defect detection unit according to the first embodiment.

FIG. 6 is a schematic perspective view for explaining scattered light generated from a chamfered portion.

FIG. 7 is a schematic side view showing a configuration of a defect detection unit according to a second embodiment.

FIG. 8 is a plan view for explaining the configuration of a pellicle frame according to another embodiment.

FIG. 9 is a schematic perspective view for explaining a pellicle and a pellicle frame.

FIG. 10 is a schematic perspective view for explaining the configuration of a pellicle frame.

[Explanation of symbols]

1 ... Pellicle, 2,30 ... Pellicle frame, 5 ...
… Foreign matter, 6 …… After shaving, 10 …… Defect inspection device, 11
...... Defect detection unit, 11A ...... House lamp, 11
B _1, 11B ₂ ...... light fiber, 11C _1, 11C ₂ ...
… Base, 11D ₁ , 11D ₂ …… Mirror, 11E …… Mirror, 11F, 21C …… Receiving lens, 11G, 21D
…… CCD, 11H, 21E …… Defect detection part, 12 ……
Drive unit, 12A ... X-axis direction drive unit, 12B ... Y-axis direction drive unit, 12C ... Rotation direction drive unit.

Claims (7)

[Claims] 1. A defect inspection apparatus for inspecting a defect of a pellicle frame on which a pellicle for dust-proofing a mask or a reticle is stretched, the upper surface of the pellicle frame being opposed to or on the upper end surface side on which the pellicle is stretched. Light irradiation means for irradiating the pellicle frame with light from the lower end surface side, light receiving means for receiving reflected light obtained by irradiating the pellicle frame with the light, and the light irradiation means and the light receiving means are fixed. Moving means for relatively moving the light irradiating means and the light receiving means with respect to the pellicle frame while maintaining the positional relationship, and defect determining means for determining the presence or absence of a defect in the pellicle frame based on the output of the light receiving means. A defect inspection apparatus comprising: 2. The light irradiating means is configured such that, with respect to a plane including the upper end surface of the pellicle frame or a plane including the lower end surface of the pellicle frame, an upper end surface or a lower end surface of the pellicle frame and the pellicle frame. Edge which becomes the boundary with the inner wall surface or the outer wall surface,
2. The defect inspection apparatus according to claim 1, wherein the light is irradiated at an angle at which scattered light does not occur from an inner wall surface or an outer wall surface of the pellicle frame. 3. The light irradiating means irradiates the inner wall surface or the outer wall surface with the light so as to be substantially symmetrical from both sides of the inner wall surface or the outer wall surface of the pellicle frame. Item 2. The defect inspection device according to item 2. 4. The defect inspection apparatus according to claim 1, wherein the light receiving means is an image pickup device. 5. The light receiving means is arranged so as to form an angle of approximately 30 ° to 60 ° with respect to the inner wall surface or the outer wall surface.
The defect inspection device described in 1. 6. The defect inspection apparatus according to claim 1, wherein the irradiation unit emits white light as the light. 7. The defect inspection apparatus according to claim 1, wherein the irradiation unit and the light receiving unit are arranged on the inner wall surface side of the pellicle frame.