JPH0736000B2 - Foreign object detection device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foreign matter adhesion prevention film (hereinafter, referred to as a film attached to a glass substrate used in a semiconductor manufacturing apparatus
The present invention relates to a foreign matter detection device on a pellicle), and more particularly to a foreign matter detection device suitable for performing a stable foreign matter inspection even when the shape and size of the inspection object change.

[0002]

2. Description of the Related Art A conventional foreign matter detecting device of this type is called a pellicle which is attached to a glass substrate such as a photomask and a reticle with a space therebetween, as described in Japanese Patent Laid-Open No. 60-67845. To irradiate the surface of the object to be inspected such as a thin film with a parallel beam from an oblique direction in a strip shape, and to collect the scattered light of the foreign matter existing in the strip irradiation section by an imaging lens to form an image on a one-dimensional image sensor. What to detect is proposed.

[0003]

SUMMARY OF THE INVENTION In the prior art described above, a single imaging lens is used to anticipate the entire illumination area on the surface of the object to be inspected.
Since the image was formed on a one-dimensional image sensor and foreign matter existing in the illumination area was detected, no consideration was given to changing the inspection area when the shape and size of the inspection object changed. There was a problem that it was not possible to cope with the diversification of inspected objects.

In view of the above-mentioned problems of the prior art, an object of the present invention is to allow foreign matter to be detected at the same reference level in the central portion and the peripheral portion of the surface of the inspection object even if the shape and size of the inspection object change. Another object of the present invention is to provide a foreign matter detection device.

[0005]

In the foreign matter detecting apparatus of the present invention, the inspection object scanning for moving the inspection object in one direction is performed.
Means and the width direction orthogonal to the moving direction of the inspection object.
With multiple light emitting elements arranged linearly
Front from a diagonal direction with a desired tilt angle with respect to the surface
An illumination means for illuminating a strip along the width direction orthogonal to each other, and
A plurality of linearly arranged along the orthogonal width direction of the surface of the object
And collects the scattered light from the surface of the object to be inspected.
It is composed of imaging lenses, and they are made by adjacent imaging lenses.
It was constructed so that the degree of overlap of the
The lens array is superimposed on each other and the image is formed.
Along the width direction orthogonal to the image forming position of the lens, respectively.
The light-shielding plates that are movably arranged,
Open at positions facing each other along the orthogonal width direction
And the area other than the detected image forming area on the surface of the inspection object.
Has an opening to block the scattered light generated from the
The length of the opening in the width direction orthogonal to the opening due to the movement
The light-shielding hand that can be changed according to the effective detection area of the inspection object.
And a photoelectric conversion device that receives light that passes through the openings of the light shielding means.
And a replacement element.

[0006]

[Action] In the foreign matter detection device of the present invention, as described above, the test
Object scanning means, illumination means, lens array, light blocking means, and light
Each light emitting element of the illumination means is provided with
If there are multiple arrangements along the width direction orthogonal to the moving direction of
In both cases, the imaging lenses of the lens array are also in the orthogonal width direction.
Since it is arranged in multiple straight lines along each
The divided area is detected by each imaging lens and the corresponding photoelectric conversion element.
To detect foreign substances existing in each area.
With the same reference level, foreign matter can be accurately measured.
It can be detected stably. In addition to this, light-shielding means
The opening length of the opening formed by the light shielding plate of the
Since it can be changed according to the size of the effective detection area of the object,
Reliable response to changes in the shape and size of the inspection object
it can. Therefore, it is possible to cover a wide range of inspection areas of the inspection object.
Therefore, it is possible to stably detect the foreign matter.

[0007]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 10 show a first embodiment of a foreign matter detecting device according to the present invention. As shown in FIG. 1, in a foreign matter detection device 11, a pellicle 3 is attached to an upper surface of a glass substrate 1 including a photomask, a reticle, and the like via a frame 2, and the surface of the pellicle 3 is symmetrically inclined in a diagonally upward direction. Is provided on the surface of the pellicle 3 and provided on the surface of the pellicle 3 with a band-shaped illumination unit (not shown) formed between them by the illumination unit 4, and the lens array 6 and the light shield are provided. A photoelectric detection unit 5 having a unit 7 and a photoelectric conversion element 8 is provided. Further, the glass substrate 1 is placed on a stage 9, and when the motor 92 is driven by a command (pulse number) of the encoder 91 on the stage 9, a feed screw 93 and a nut connected to the motor 92 are connected. It is configured to be movable in the y direction via 94. As shown in FIG. 2, the illuminating unit 4 arranges a plurality of light emitting elements 41 including semiconductor lasers, LEDs, etc. in a straight line along the x direction, and collects a light source image (light emitting point image) of each light emitting element 41. The lens 42 irradiates the surface of the pellicle 3 to form a band-shaped illumination section 43. The light emitting element 41 may be of a type incorporating a condenser lens. In that case, the condenser lens 42 becomes unnecessary. The light emitting element 41 may be a combination of an element having a linear light emitting source and the condenser lens 42.

As shown in FIG. 4, the lens array 6 shown in FIG. 1 is constructed by arranging a plurality of minutely formed image forming lenses 61 having a diameter of about 1 mm in a straight line along the x direction. Has been done. As shown in FIG. 3, the image forming lens 61 is formed of a lens having a parabolic refraction distribution 62 from the center to the periphery. Therefore, when the incident light 63 enters the image forming lens 61, it is incident. The light 63 travels in a sine shape or a helical shape at a constant cycle, whereby it is possible to image the central portion of the surface of the pellicle 3 and its peripheral portion with the same sensitivity. Further, as shown in FIG. 4, the imaging lens 61 is linearly arranged along the x direction, so that the foreign matter 10 present on the surface of the pellicle 3 can be detected over a wide range. That is, the imaging area (field of view) 64 of each imaging lens 61 is about several mm,
Since this is projected on the light receiving surface of the photoelectric conversion element 8, it is possible to detect over a wide range by arranging a plurality of imaging lenses 61 in a straight line. Further, by arranging a plurality of the image forming lenses 61 in a straight line, the image projected on the light receiving surface of the photoelectric conversion element 8 is the image forming lenses 61.
The projected images of are overlapped. That is, the imaging lens 61 has a light amount distribution 65 as shown in FIG. 5, and the light amount of the lens array 6 (FIG. 1) is the sum of the light amounts of the individual imaging lenses 61. Therefore, the imaging lens 6
Even if the foreign matter 10 is the same in the center and the periphery in the image forming area 64, the light receiving intensity of the light receiving surface of the photoelectric conversion element 8 is slightly different. ing. In order to eliminate this, the imaging lens 61
It is necessary to reduce the array pitch P of (1) and increase the degree of overlap (overlap) of the imaging regions 64 of the adjacent imaging lenses 61. As a result, it is possible to mitigate the light amount unevenness 66 and prevent the foreign matter 10 from being overlooked. For example, as shown in FIG. 6, the above-mentioned problem can be solved by arranging the imaging lenses 61 linearly in the x direction and in a zigzag pattern at high density. However, in that case, the photoelectric conversion element 8 needs to be a light receiving surface having a size capable of receiving the image forming regions 64 of two rows of the image forming lens 61.

The light-shielding means 7 shown in FIG. 1 has two flat light-shielding plates 71a and 71b which are superposed on each other and arranged to be movable in the x direction as shown in FIG. Openings 72a, 72b formed on the opposite end surfaces of the plates 71a, 71b and having a predetermined length in the x direction.
And a motor 74 that rotates in both forward and reverse directions 73a and 73b.
And the feed screw 76 connected to the motor 74 and having a left screw portion 75a and a right screw portion 75b, and screwed to the left screw portion 75a and the right screw portion 75b respectively, and the two light shielding plates 71a, 71b. Of the two nuts 77a and 77b fixed to the end face in the y direction of the motor, and by rotating the motor 74 in the forward direction 73a or in the reverse direction 73b, the two light shielding plates 71a and 71b are opposed to each other. Moving inward or inward, the two openings 72a,
The opening length 1 of 72b is made variable, whereby stray light can be prevented and the foreign matter 10 can be stably detected even if the shape and dimensions of the glass substrate 1 and the pellicle 3 in the x direction change. That is, as shown in FIG. 7, stray light is scattered light 44 from the frame 2 to which the pellicle 3 is attached.
And the light that has passed through the pellicle 3 is reflected on the surface 11 of the glass substrate 1.
Scattered light 45 generated by striking the circuit pattern 12 formed in the above is considered. These stray lights are photoelectric conversion elements 8
In order to prevent the light receiving surface of the foreign matter 10 from reaching the light receiving surface of the pellicle 3 as shown in FIG. It is necessary to detect the foreign matter 10 on the pellicle 3 within the effective detection area 31.

Therefore, in the present invention, as shown in FIG. 7, the light shielding means 7 is installed immediately in front of the lens array 6 side of the photoelectric conversion element 8, and the openings 72a, 7a of the light shielding means 7 are provided.
As shown in FIGS. 8 and 9, the opening length 1 of 2b is variably formed corresponding to the shape and size of the effective detection area 31, so stray light is prevented and stable detection of the foreign matter 10 is performed. It is possible. In general, after cleaning the glass substrate 1 of the pellicle 3 (FIG. 7), it was confirmed that the circuit pattern forming surface 11 and the non-forming surface of the glass substrate 1 were free of minute foreign matters of about 1 to 2 μm. Although it is attached to both surfaces of the glass substrate 1 above, the shape and size of the glass substrate 1 are changing as the circuit pattern 12 is miniaturized, and at the same time, the shape and size of the pellicle 3 are diversified. Needs to address all of these. On the other hand, in the light-shielding means 7 of the present invention, the opening lengths 1 of the openings 72a and 72b are variable (FIG. 8), so that the glass substrate 1 and the pellicle 3 are surely diversified in shape and size. It is possible to respond.

As shown in FIGS. 4 and 5, the photoelectric conversion element 8 receives a foreign substance image 10 'from the light-shielding means 7 when it is projected onto a light receiving surface formed by a plurality of pixels. Outputs an electric signal 81 (see FIG. 10) according to
The electric signal 81 is compared with an electric signal level (reference level, threshold value) corresponding to the received light intensity of the formation dimension of the foreign matter 10 to be detected in advance, and when the electric signal 81 becomes higher or lower than the reference level, the foreign matter It is configured to detect the presence of 10. Although not shown, the photoelectric conversion element 8 is formed so that the position of the pixel outputting the electric signal 81 can be known by counting the drive pulse of each pixel, so that the pellicle 3 is formed. It is possible to know the existing position of the foreign matter 10 in the upper x direction.

Since the foreign matter detecting device 11 according to the present invention is constructed as described above, a method of inspecting a foreign matter will be described below. After mounting the pellicle 3 through the frame 2 on the glass substrate 1 installed on the stage 9 shown in FIG. 1, the motor 92 of the stage 9 is driven to drive the glass substrate 1
Is moved to the setting position 13 shown by the solid line in FIG. 9 by moving in the y direction, the electric signal 81 of the photoelectric conversion element 8 is changed to that shown in FIG.
As shown in, the electric signal 8 of the reflected light of the frame 2 of the pellicle 3
2, 83 and the electric signal 84 of the scattered light by the foreign matter 10 on the pellicle 3. In this case, the electric signals 82 and 83 other than the foreign matter 10 are all stray light. Therefore, according to the present invention, the electric signal 81 of the photoelectric conversion element 8 is used to detect the frame 2 of the pellicle 3.
The inner space L of the light shielding means 7 is calculated, and the effective detection area 31 corresponding to the space L is calculated so as to match the length of the effective detection area 31 in the x direction.
After the opening length 1 of 2b is set, the glass substrate 1 is moved in the y direction by the drive of the motor 92 of the stage 9, and the inspection origin 14 (the end face of the glass substrate 1 as shown in FIG. 9) is obtained. Is returned to the set position 13 in the y direction indicated by the solid line and is again moved in the opposite direction by the driving of the motor 92 of the stage 9, whereby the foreign matter 10 on the surface of the pellicle 3 is moved. Is detected. The setting position 13 in the y direction may be set to any position as long as the electric signals 82 and 83 of the reflected light of the frame 2 of the pellicle 3 can be obtained as the electric signal 81 of the photoelectric conversion element 8. However, ideally, it should be closer to the inspection origin 14.

In the foreign matter detecting apparatus of the embodiment, a plurality of light emitting elements 41 of the illumination means 4 are arranged along the x direction, and a plurality of imaging lenses 61 of the lens array 6 are also linear along the x direction. Since each of the divided areas is disposed in the photoelectric conversion element 8 corresponding to each imaging lens 61,
Since it is possible to detect the foreign matter 10 existing in the respective areas by detecting with the and, it is possible to accurately and stably detect the foreign matter 10 at the same reference level. to this
In addition, the opening formed by the light blocking plates 71a and 71b
The opening length l of 72a and 72b is effective for the frame 2 of the pellicle 3.
Since it is variable according to the size of the detection area 31,
Reliable even if the dimensions of the substrate 1 and pellicle 3 change
Can correspond to. Therefore, it is possible to stably detect the foreign matter over a wide inspection area of the pellicle 3.

Next, another embodiment of the present invention will be described with reference to FIGS. In the embodiment shown in FIG. 11, the illuminating means 4 is installed in a right obliquely upward direction with respect to the surface of the pellicle 3,
This is a case where the photoelectric detection unit 5 including the lens array 6, the light shielding unit 7, and the photoelectric conversion element 8 is installed in the upper left diagonal direction opposite to this. Further, in the embodiment shown in FIG. 12, the illumination means 4 is installed right above the pellicle 3 so that the position of the strip-shaped illumination portion formed on the pellicle 3 can be detected by the illumination means 4 in the obliquely upward and leftward directions. This is a case where the photoelectric detection means 5 having the lens array 6, the light shielding means 7, and the photoelectric conversion element 8 in a set is installed. Also in each of these embodiments, FIG.
Through this, the same effect as that of the embodiment shown in FIG. 10 can be exhibited. Further, the embodiment shown in FIG. 13 is a case where the foreign matter 10 existing on the surface of the pellicle 3 attached to the lower side of the glass substrate 1 is detected. In this case, the foreign matter detection device 1 having the structure shown in FIGS.
The foreign object 10 can be detected by installing two sets of 1.

[0015]

As described above, according to the present invention, according to the present invention, the
Inspection object scanning means, illumination means, lens array, light shielding means
Equipped with a photoelectric conversion element, each light emitting element of the illumination means is inspected
Plural arrays are arranged along the width direction orthogonal to the moving direction of the object.
In addition, the imaging lens of the lens array also has the width in the orthogonal direction.
Arranged in multiple straight lines along each direction, and each divided area
Is detected by each imaging lens and the corresponding photoelectric conversion element, and
It is possible to detect foreign substances existing in each area.
Since it is configured like this, it is possible to accurately measure foreign matter at the same reference level.
Stable detection, and the shading of the shading means
The opening length of the opening formed by the plate is
It is configured to be variable according to the size of the effect detection area.
Therefore, even if the shape and size of the object to be inspected changes, it is possible to respond reliably.
As a result, the industrial effect is great.

[Brief description of drawings]

FIG. 1 is a perspective view in which a first embodiment of a foreign matter detection device according to the present invention is applied to a glass substrate used in a semiconductor device.

FIG. 2 is an enlarged perspective view of the lighting unit shown in FIG.

3 is a characteristic explanatory view of an imaging lens forming the lens array shown in FIG.

FIG. 4 is an enlarged perspective view showing a lens array.

FIG. 5 is a perspective view showing a method for preventing unevenness in light amount of the lens array.

FIG. 6 is a perspective view showing another method for preventing unevenness in light amount of the lens array.

FIG. 7 is an explanatory diagram of stray light other than foreign matter.

FIG. 8 is an enlarged perspective view of the light shielding unit shown in FIG.

FIG. 9 is a plan view of a glass substrate with a pellicle.

FIG. 10 is an explanatory diagram showing the relationship between the reflected light of the pellicle frame and the electric signal due to the scattered light of foreign matter on the pellicle film.

FIG. 11 is an explanatory view showing another embodiment of the foreign matter detecting device according to the present invention.

FIG. 12 is an explanatory view showing still another embodiment of the foreign matter detecting device according to the present invention.

FIG. 13 is an explanatory view showing still another embodiment of the foreign matter detecting device according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Glass substrate, 2 ... Frame, 3 ... Pellicle, 4 ... Illumination means, 41 ... Light emitting element, 43 ... Band illumination part, 5 ... Photoelectric detection means, 6 ... Lens array, 61 ... Imaging lens, 7 ... Shading means , 71a, 71b ... Shading plate, 72a, 72b ... Opening
Part, 8 ... Photoelectric conversion element, 10 ... Foreign matter, 11 ... Foreign matter detection device.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP 61-123270 (JP, A) JP 55-149829 (JP, A) JP 59-99237 (JP, A) JP 54- 13751 (JP, B2) Actual public Sho 51-22707 (JP, Y2)

Claims (1)

[Claims] 1. When illuminating the surface of an object to be inspected,
Therefore, the scattered light from foreign matter existing on the surface of the inspection object can be detected.
In the foreign matter detection device that comes out, the object to be inspected in one direction
Inspecting object scanning means for moving and moving method of the inspecting object
The lines are arranged in a straight line along the width direction orthogonal to the
Has an optical element and has a desired tilt angle with respect to the surface of the object to be inspected.
From the diagonal direction along the width direction orthogonal to the above.
Illuminating means that illuminates and the width direction of the surface of the inspection object which is orthogonal to
Are arranged in a straight line along the
Consists of an imaging lens that collects scattered light from
The degree of overlap between the image forming areas due to the matching image forming lenses is large.
Lens array configured to
And at the same time to the image forming position of the image forming lens.
A light shield that is movably arranged along the width direction
The plate and the direct shields at the positions facing each other of the respective shading plates.
The object to be inspected is opened along the intersecting width direction.
Blocks scattered light generated from areas other than the detection and imaging area on the surface
The opening has an opening, and the movement of the light shielding plate causes the aforementioned
The orthogonal opening width in the width direction is set as the effective detection area of the inspection object.
Correspondingly variable light blocking means and the opening of the light blocking means
A foreign matter detection device, comprising: a photoelectric conversion element that receives excess light .