JPH09145631A - Surface foreign matter detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure foreign matter positions extending over the entire surface to-be- inspected with high precision by detecting the positions of foreign matters based on the time detecting the foreign matter in the first band-shaped irradiating area and the second band-shaped irradiating area which forms an irradiation means, and relative moving speed between the to-be-inspected surface and the irradiation means. SOLUTION: The light emitted from a light source 10 forms a band-shaped irradiation area 2 on the surface of a pellicle film 1 spread on a mask, through an irradiation optical system 11. The mask is held on a stage which is allowed to move along the x-direction so that the surface of the film 1 is parallel to the x-y flat surface. The area 2 is formed along the y-direction perpendicular to the scanning direction, and the stage is driven in the x-direction, and the entire surface of the film 1 can be scanned with the area 2. The scattered light from the area 2 is made incident to the end surface of a fiber bundle 12 into which multiple optical fiber is bundled, and converged on the photodetecting surface of a photoelectric conversion element 13. The element 13 outputs the scattering signal corresponding to the intensity of the scattered light from the foreign matter of the element 13, and the foreign matter is detected based on the signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface foreign matter inspection apparatus for inspecting foreign matter adhering to a surface to be inspected, and particularly to a foreign matter position on a pellicle film of a large mask for an exposure machine for printing a circuit pattern such as a flat panel display. Relating to a device for inspecting.

[0002]

2. Description of the Related Art In a process of manufacturing a circuit pattern for a flat panel display or the like, a pattern formed on a mask on which a thin film for preventing foreign matter, that is, a pellicle is stretched is transferred onto a photosensitive substrate. At this time, if a large foreign matter such as dust adheres to the pellicle film, the foreign matter image is transferred onto the substrate, causing a defect in the circuit pattern. Therefore, it is necessary to inspect the presence and position of the foreign matter by using the surface foreign matter inspection apparatus before the transfer.

In this type of conventional surface foreign matter inspection apparatus, a scanning optical system is used to scan a beam spot on a surface to be inspected, and a scattered light from a foreign matter (fine dust or the like) on the beam spot is received by an optical receiving system. Have detected through. Alternatively, the surface to be inspected is illuminated with illumination light, and the scattered light from the foreign matter with respect to the illumination light is detected via an image detection element such as a CCD. When the image is detected by the image detection element, the detection area on the surface to be inspected may be reduced and projected onto the image detection element via the reduction projection optical system in order to obtain a wide detection visual field.

[0004]

By the way, a mask for an exposure machine for printing a circuit pattern on a flat panel display or the like is becoming larger. Therefore, in the conventional inspection device that scans the beam spot, the scanning range is increased with the increase in size of the mask. As a result, the required fields of view of the scanning optical system and the light receiving optical system are increased, and it becomes difficult to design and manufacture the optical system. In addition, since the size of each optical element increases as the required field of view increases, the degree of freedom in its arrangement also decreases.

On the other hand, even in the conventional inspection apparatus for detecting with the image detecting element, it is necessary to increase the size of each optical element or decrease the reduction ratio of the light receiving optical system with the increase in size of the mask. As a result, the size of the inspection apparatus may increase, and the detection sensitivity of the foreign matter position may change depending on the position.

The present invention has been made in view of the above-mentioned problems, and a surface foreign matter inspection capable of highly accurately detecting a foreign matter position over a large inspected surface without increasing the size of the apparatus. The purpose is to provide a device.

[0007]

In order to solve the above-mentioned problems, in the present invention, an irradiation means for forming a belt-shaped irradiation region on a surface to be inspected, and a direction crossing the longitudinal direction of the belt-shaped irradiation region. A surface provided with scanning means for moving the surface to be inspected relative to the irradiation means, and detection means for detecting the position of the foreign matter based on scattered light from the foreign matter in the belt-like irradiation region In the foreign matter inspection device, the irradiation means includes a first strip-shaped irradiation region and the first strip-shaped irradiation region.
And a second strip-shaped irradiation region in which the interval between the strip-shaped irradiation region and the second strip-shaped irradiation region is monotonically changed, and the detection unit detects the foreign matter in the first strip-shaped irradiation region and the second strip-shaped irradiation region. There is provided a surface foreign matter inspection apparatus characterized in that the position of the foreign matter is detected based on the time when the foreign matter is detected in the area and the relative movement speed of the surface to be inspected and the irradiation means.

According to a preferred aspect of the present invention, the first
Band-shaped irradiation region is formed along a first straight line direction perpendicular to the scanning direction, and the second band-shaped irradiation region crosses the first straight line direction at a predetermined angle. Are formed along the straight line direction.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a first band-shaped irradiation region and a second band-shaped irradiation region in which the interval between the first band-shaped irradiation region and the first band-shaped irradiation region monotonously changes are formed on the surface to be inspected. .
Then, the surface to be inspected is scanned along the predetermined direction in the first strip-shaped irradiation region and the second strip-shaped irradiation region. In this way, the position of the foreign matter can be detected based on the time when the foreign matter is detected and the scanning speed in each band-shaped irradiation region.

According to a specific embodiment, the first strip-shaped irradiation region is arranged along the direction perpendicular to the scanning direction, and the second strip-shaped irradiation region is inclined with respect to the first strip-shaped irradiation region. Form along. In this case, the foreign matter position along the scanning direction is detected based on the time when the foreign matter is detected in the first strip irradiation area and the scanning speed, and the scanning orthogonal direction is determined based on the time difference when the foreign matter is detected in each strip irradiation area and the scanning speed. It is possible to detect the position of each foreign object along the line.

As described above, according to the present invention, the presence or absence of scattered light from a foreign matter in each irradiation region is simply detected.
The foreign object position can be detected. Therefore, even if the surface to be inspected is large, the detection sensitivity does not fluctuate over the entire surface, and the position of the foreign matter can be detected with high accuracy. Also,
An optical system for detecting scattered light from a foreign substance may have a simple configuration including, for example, a light guide having an incident end extending along a predetermined direction. As a result, it is possible to cope with an increase in the size of the surface to be inspected by simply increasing the incident end of the light guide in a predetermined direction without increasing the size of the entire device.

Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view schematically showing the structure of a surface foreign matter inspection apparatus according to the first embodiment of the present invention. FIG.
It is a figure which shows two strip | belt-shaped irradiation areas formed in the surface of the pellicle film 1 of FIG. In FIG. 1, only the irradiation means and the detection means corresponding to one of the two belt-shaped irradiation areas 2 and 3 are shown, and the irradiation means and the detection means corresponding to the other belt-shaped irradiation area 3 are shown. Is omitted.

In FIG. 1, the light emitted from the light source 10 is passed through an appropriate irradiation optical system 11 and a mask (not shown).
A belt-shaped irradiation region 2 on the surface of the pellicle film 1 stretched over the
To form The mask is held on a stage (not shown) movable in the x direction so that the surface of the pellicle film 1 is parallel to the xy plane. Also, the irradiation area 2
Are formed along the y direction orthogonal to the scanning direction. Therefore, by driving the stage in the x direction,
The entire surface of the pellicle film 1 can be scanned by the irradiation area 2.

The scattered light from the irradiation area 2 is incident on the end face of a fiber bundle 12 which is a light guide means constituted by bundling a large number of optical fibers. The scattered light guided through the fiber bundle 12 is condensed on the light receiving surface of the photoelectric conversion element 13 such as a photomultiplier tube or a silicon photodiode. Then, the photoelectric conversion element 13 outputs a scattered signal according to the intensity of scattered light from the foreign matter. In this way, the foreign matter can be detected based on the scattered signal.

As described above, the light source 10 and the irradiation optical system 1
Reference numeral 1 constitutes irradiation means for forming a first strip-shaped irradiation region 2 on the surface of the pellicle film 1 which is the surface to be inspected. Further, the fiber bundle 12 and the photoelectric conversion element 13 constitute a detection means for receiving scattered light from the foreign matter in the first band-shaped irradiation region 2 and detecting the foreign matter.

In the first embodiment, as shown in FIG. 2, in addition to the first strip-shaped irradiation region 2 along the direction (y-direction) perpendicular to the scanning direction (x-direction), the second strip-shaped irradiation region is provided. 3 is formed. The second strip-shaped irradiation region 3 is formed along the direction crossing the scanning direction and intersecting the longitudinal direction of the first strip-shaped irradiation region 2 at a predetermined angle θ. As described above, in FIG. 1, the irradiation means and the detection means corresponding to the second band-shaped irradiation area 3 are omitted, but the configuration is such that the irradiation means and the detection means corresponding to the first band-shaped irradiation area 2 are omitted. The structure of the detecting means is basically the same.

As described above, each output signal generated by converting the scattered light from the first and second strip-shaped irradiation regions by each photoelectric conversion element is input to a signal processing system (not shown). Further, driving information such as the scanning speed from the stage holding the mask as the object to be inspected is also input to the signal processing system. Then, the signal processing system executes a predetermined calculation described below to detect the position of the foreign matter.

FIG. 3 is a diagram showing scattered signals detected in the first embodiment, where (a) shows scattered signals from the first band-shaped irradiation region 2 and (b) shows second band-shaped irradiation. Scatter signals from region 3 are shown respectively. In FIG. 3, the horizontal axis represents the time with reference to the detection start time, and the vertical axis represents the intensity of the optical signal detected from each irradiation region. In FIG. 3, the optical signal from the irradiation region 2 is detected at the time point when time T has elapsed from the detection start time,
Irradiation area 3 at the time when Δt has further elapsed
The state where the optical signal from is detected is shown.

A method for determining the position of the foreign matter 4 on the surface of the pellicle film 1 will be described below with reference to FIGS. 2 and 3. Generally, in the x direction, the position of the irradiation region 2 at the time of starting the detection can be set as the origin. In many cases, scattered light from the edge of the mask or the frame of the pellicle film 1 is detected from the irradiation region 2 almost at once, so that the scattered light can be used as a trigger to start detection. In FIG. 2, the position where the irradiation region 2 reaches the frame of the pellicle film 1 is the origin 0 in the x direction.

On the other hand, with respect to the y direction, a position where the distance between the irradiation region 2 and the irradiation region 3 along the x direction is known can be set as the origin. In FIG. 2, the position where the distance between the irradiation region 2 and the irradiation region 3 along the x direction is a is set as the origin 0 in the y direction.

Under the above conditions, the coordinates (x,
y) is represented by the following equations (1) and (2). x = v · T (1) y = (v · Δt−a) cot θ (2) where, v: scanning speed

As described above, in the first embodiment, the foreign matter position along the scanning direction (x direction) is detected based on the scanning time v and the time T when the foreign matter 4 is detected in the first band-shaped irradiation region 2. be able to. Further, it is possible to detect the foreign matter position along the scanning orthogonal direction (y direction) based on the scanning time difference Δt and the scanning speed v at which the foreign matter 4 is detected in each of the strip-shaped irradiation regions 2 and 3.

As described above, in the first embodiment, the position of the foreign matter can be detected only by detecting the presence or absence of scattered light from the foreign matter in the irradiation areas 2 and 3. Therefore, even if the pellicle film 1 that is the surface to be inspected is large, the detection sensitivity does not fluctuate over the entire surface, and the position of the foreign matter can be detected with high accuracy. Further, it is possible to cope with the increase in size of the surface to be inspected by simply increasing the incident end of the fiber bundle 12 in a predetermined direction without increasing the size of the entire apparatus.

FIG. 4 is a perspective view schematically showing the structure of a surface foreign matter inspection apparatus according to the second embodiment of the present invention. Also in FIG. 4, only the irradiation means and the detection means corresponding to one of the two belt-shaped irradiation areas are shown, and the irradiation means and the detection means corresponding to the other belt-shaped irradiation area are omitted. There is. The second embodiment and the first embodiment have almost the same configuration, but in the second embodiment, the lens array 14 and the field stop 15 are arranged in the optical path between the irradiation region 2 and the fiber bundle 12. Only the points are basically different from the first embodiment. Therefore, in FIG. 4, elements having the same functions as those in FIG. 1 are denoted by the same reference numerals as in FIG. Hereinafter, the second embodiment will be described focusing on the differences from the first embodiment.

As shown in FIG. 4, in the second embodiment, after the scattered light from the irradiation area 2 is condensed through the lens array 14, the field stop disposed optically conjugate with the irradiation area 2. It is incident on 15. That is, only the scattered light from the irradiation region 2 that is collected through the lens array 14 reaches the incident end of the fiber bundle 12 through the field stop 15. As described above, in the second embodiment, the light other than the scattered light from the irradiation region 2 is configured to hardly reach the incident end of the fiber bundle 12, so that so-called stray light is avoided and highly accurate detection is possible. become.

Although the irradiation area 2 is orthogonal to the scanning direction in the first embodiment, the longitudinal direction of the irradiation area 2 need not necessarily be orthogonal to the scanning direction. . An essential point in the present invention is that the two irradiation areas are formed so as to cross the scanning direction, and the interval between the two irradiation areas changes monotonically. Further, in each of the above-mentioned embodiments, as an optical element for converting the visual field of the belt-shaped irradiation area onto the light receiving surface of the photoelectric conversion element,
A fiber bundle is used. However, instead of a fiber bundle, an optical element such as an integrated photoconductive rod may be used.

Further, in the present invention, without using a light guide means such as a fiber bundle, for example, as shown in FIG.
As shown in FIG. 3, photoelectric conversion elements 130 such as strip-shaped (rectangular) CCDs are arranged at positions where scattered light from each strip-shaped irradiation region 2 can be detected, and scattered light from the first strip-shaped irradiation region The photoelectric conversion element may be photoelectrically detected by the first photoelectric conversion element, and the scattered light from the second band-shaped irradiation region may be photoelectrically detected by the second photoelectric conversion element.

Further, in each of the above-described embodiments, an example is shown in which scattered light from the two irradiation areas is received by separate detecting means. However, particularly when the light receiving system as in the second embodiment is adopted, the light receiving region is limited by the cooperative action of the lens array 14 and the field stop 15. Therefore, the entire two irradiation regions are combined into one irradiation optical system. Irradiation may be through the system. Further, in each of the above-described embodiments, an example in which two irradiation areas are formed is shown, but three or more irradiation areas may be formed in order to improve the sensitivity of position detection and the like.

[0029]

As described above, in the present invention, two strip-shaped irradiation regions are formed, and the foreign substance position is detected based on the time when the foreign substance is detected in each strip-shaped irradiation region and the scanning speed.
That is, the position of the foreign matter can be detected only by detecting the presence or absence of scattered light from the foreign matter in each irradiation region.
Therefore, even if the surface to be inspected is large, the detection sensitivity does not fluctuate over the entire surface, and the position of the foreign matter can be detected with high accuracy. Further, it is possible to cope with the increase in size of the surface to be inspected by simply increasing the incident end of the fiber bundle in a predetermined direction without increasing the size of the entire apparatus.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a configuration of a surface foreign matter inspection apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing two strip-shaped irradiation regions formed on the surface of the pellicle film 1 of FIG.

3A and 3B are diagrams showing scattered signals detected in the first embodiment, wherein FIG. 3A is a scattered signal from the first band-shaped irradiation region 2 and FIG. 3B is a second band-shaped irradiation region 3. The scatter signals of are shown respectively.

FIG. 4 is a diagram schematically showing a configuration of a surface foreign matter inspection apparatus according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a schematic configuration of a modified example of the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pellicle film 2 1st strip | belt-shaped irradiation area | region 3 2nd strip | belt-shaped irradiation area | region 4 Foreign material 10 Light source 11 Irradiation optical system 12 Fiber bundle 13 Photoelectric conversion element 14 Lens array 15 Field stop

Claims (6)

[Claims] 1. An irradiation unit for forming a belt-shaped irradiation region on a surface to be inspected, and a unit for moving the surface to be inspected relative to the irradiation unit in a direction transverse to a longitudinal direction of the band-shaped irradiation region. In a surface foreign matter inspection device comprising a scanning means and a detection means for detecting the position of the foreign matter based on the scattered light from the foreign matter in the strip-shaped irradiation area, the irradiation means is a first strip-shaped irradiation area. A second band-shaped irradiation region in which a distance between the first band-shaped irradiation region and the second band-shaped irradiation region monotonously changes, and the detection unit detects the foreign matter in the first band-shaped irradiation region, 2. A surface foreign matter inspection apparatus, which detects a position of the foreign matter based on a time when the foreign matter is detected in the band-shaped irradiation area of No. 2 and a relative moving speed between the surface to be inspected and the irradiation means. 2. The first strip-shaped irradiation region is formed along a first linear direction perpendicular to the scanning direction, and the second strip-shaped irradiation region is formed with respect to the first linear direction. 2. The surface foreign matter inspection apparatus according to claim 1, wherein the surface foreign matter inspection apparatus is formed along a second linear direction that intersects at a predetermined angle. 3. The surface foreign matter inspection according to claim 1, wherein the scanning unit is a stage unit that holds an object having the surface to be inspected and is movable along the scanning direction. apparatus. 4. The irradiation means forms a first irradiation system for forming the first strip-shaped irradiation region on the surface to be inspected and a second strip-shaped irradiation region on the surface to be inspected. A second irradiation system for receiving the scattered light from the first band-shaped irradiation region and propagating the scattered light from the first belt-shaped irradiation region, and the first light guide unit. A first photoelectric conversion element for photoelectrically converting scattered light from the first strip-shaped irradiation region, and second light guide means for receiving and propagating scattered light from the second strip-shaped irradiation region. 4. A second photoelectric conversion element for photoelectrically converting scattered light from the second strip-shaped irradiation region via the second light guide means, and the second photoelectric conversion element according to claim 1. The surface foreign matter inspection device described in. 5. The first detection means for collecting scattered light from the first band-shaped irradiation area, and the detection means for collecting scattered light from the second band-shaped irradiation area. A second lens array, a first field stop provided at a position that is substantially optically conjugate with the first band-shaped irradiation region, and a position that is optically substantially conjugate with the second band-shaped irradiation region. A second field stop provided in the first light guide means for receiving scattered light from the first band-shaped irradiation region via the first lens array and the first field stop. , The second light guide means,
The surface foreign matter inspection device according to claim 4, wherein the scattered light from the second band-shaped irradiation region via the second lens array and the second field stop is received. 6. The irradiation means includes a first irradiation system that forms the first strip-shaped irradiation area on the test surface, and a second irradiation system that forms the second strip-shaped irradiation area on the test surface. And a first photoelectric conversion element that receives scattered light from the first band-shaped irradiation region and photoelectrically converts the scattered light from the first band-shaped irradiation region; and a photoelectric conversion device that receives scattered light from the second band-shaped irradiation region. And a second photoelectric conversion element that operates.
The surface foreign matter inspection device according to claim 1.