JPH06180294A - Defect inspection apparatus - Google Patents

Abstract

PURPOSE:To inspect a defect surfaces of reticles, masks or pellicles having different sizes by one inspection apparatus by providing slits for limiting a length of an incident light in a predetermined section in response to a length of a region to be inspected at a position substantially conjugate with an irradiated position on the surface to be inspected of the matter to be inspected. CONSTITUTION:Slits 22, 23 are provided on shielding plates 20, 21 switchably provided on a flat surface conjugate with a scanning line LR via a light receiving lens 12 in a direction conjugate with the line LR. The plates 20, 21 can be switched by a driver. When a 6-inch reticle 2 is inspected, the plate 20 is interposed between the lens 12 and a detector 13. A length of the slit 22 is so provided at points L', R' that a light from an entire area of the line LR is incident on the detector 13. When a 5-inch reticle 1 is inspected, the plate 21 is interposed between the lens 12 and the detector 13, and a length of the slit 23 is so provided that at points P', Q' are both ends.

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 more particularly to an apparatus for detecting defects such as a reticle, a mask (hereinafter referred to as "reticle") used in a semiconductor exposure process, and a foreign substance attached to the surface of a pellicle. It is a thing.

[0002]

2. Description of the Related Art FIG. 5 is an explanatory diagram showing the structure of a conventional defect inspection apparatus. Now, as a reticle with different sizes,
Consider 5 inches × 5 inches × thickness 0.09 inches (hereinafter abbreviated as 5 inches reticle) and 6 inches × 6 inches × thickness 0.25 inches (hereinafter abbreviated as 6 inches reticle).

5 inch reticle 1 and 6 inch reticle 2
Is placed on the stage 3 on the XY plane such that the inspection surfaces 1A and 2A are at the same height position Z. The stage 3 can be rotated about the drive shaft 4 in the θ direction by the drive unit 5, and can be moved in the Y direction by the drive unit 6. The stage 3 can also be moved in the z direction by the drive unit 6.

A light beam emitted from a light source 1 such as a laser is deflected and scanned by a scanner 8 such as a polygon scanner or a galvanic scanner, and a scanning lens 9 forms a focused spot 10 on the inspection surface 2A or 1A. The point L to the point R is scanned (the straight line LR is called a scanning line). Further, a deflection angle detecting means (not shown) for detecting the deflection angle of the scanner 8 is provided, and the adhesion position of the foreign matter can be detected based on the signal from the deflection angle detecting means.

The distance from the point L to the point R is d. By the scanning of the spot 10, scattered light is generated from the foreign matter 11,
It is detected by a photomultiplier or the like 13 via the light receiving lens 12. The detector 13 has a photoelectrically converted output 14
Is output. The light shield plate 1 is provided at a position almost conjugate with the scanning line LR.
5 is provided, and a substantially rectangular slit 16 is provided in a direction conjugate with the scanning line LR.

The scattered and diffracted light from the scanning line LR passes through the slit 16 and reaches the detector 13, but the scanning line LR
Stray light such as ghosts and flares generated in other locations is shielded by the light shielding plate 15 and does not reach the detector 13.

If the detector 13 receives the scattered light from the foreign substance 11, the X of the foreign substance 11 is detected from the signal from the deflection angle detecting means (not shown) for detecting the deflection angle of the scanner 8 at that time.
The attachment position in the Y direction can be known from the signal of the length measuring device such as a rotary encoder (not shown) provided in the drive unit 6, and the XY coordinates of the foreign substance 11 can be known. Moreover, the size of the foreign matter 11 can be known from the size of the signal intensity of the output 14.

FIG. 5 shows a state in which the 6-inch reticle 2 is inspected. After inspecting the 6-inch reticle 2, the drive unit 5 rotates the stage 3 180 degrees to turn the 5-inch reticle. By inspecting 1, both the 5-inch reticle 1 and the 6-inch reticle 2 can be inspected.

[0009]

In the prior art as described above, the length d of the scanning line LR is the same when inspecting the 5-inch reticle 1 and when inspecting the 6-inch reticle 2. Furthermore, since the length d has a relationship of 5 inches <d <6 inches, when the length d of the scanning line LR is determined in accordance with the inspection area of the 6 inch reticle, when the 5 inch reticle 1 is inspected, 5 When the spot 10 hits the end surface 1B of the inch reticle 1, strong stray light is emitted, and the S / N of the detection output 14 is significantly reduced.

FIG. 6 is a schematic diagram showing multiple reflected light of the light beam on the side surface of the 5-inch reticle. As shown in the figure, when inspecting the 5-inch reticle 1, the light beam 17
However, there is a problem in that the side surface of the reticle end surface 1B shines when the multiple-reflected light reaches the point A.

Because the 5 inch reticle 1 is usually
This is because the end surface 1B has a ground glass shape, so that at point A, light is also scattered inside the reticle 1, and the end surfaces 1B at both ends of the side surface also shine.

On the other hand, in the 6-inch reticle 2, since the end face 2B is not normally ground glass and is optically polished, even if the multiple reflected light strikes the reticle end face, it is simply refracted and the side face of the end face 2B is changed. There is nothing that shines.

It is an object of the present invention to provide a defect inspection apparatus capable of inspecting defects on the surface of a reticle, a mask or a pellicle having different sizes with a single defect inspection apparatus.

[0014]

In the defect inspection apparatus according to the invention described in claim 1, the surface or pattern surface of a transfer original plate such as a reticle or mask used for exposure transfer of a fine pattern onto a photosensitive substrate, or Is a defect inspection device for optically inspecting an inspected surface of an inspected object such as a surface of a pellicle mounted on the transfer original plate, and an irradiation means for irradiating the inspected surface of the inspected object with light. An apparatus comprising: a supply unit that supplies a plurality of surfaces of the object to be inspected having different sizes onto an optical scanning line of the irradiation unit; and a detection unit that receives light from the surface to be inspected of the object to be inspected. In the above, the position of the incident light on the light receiving part of the detection means is provided at a position substantially conjugate with the irradiation position on the surface to be inspected of the inspection object, and according to the length of the inspection area of the plurality of inspection objects. A light-receiving part limiting device that limits the length of a given cross section Those were example.

In the defect inspection apparatus according to the second aspect of the present invention, the surface or pattern surface of a transfer original plate such as a reticle or mask used for exposure transfer of a fine pattern onto a photosensitive substrate or the transfer original plate is mounted. A defect inspection apparatus for optically inspecting an inspected surface of an inspected object such as a surface of a pellicle, the size of which is different from that of an irradiation unit for irradiating the inspected surface of the inspected object with light. An apparatus comprising: a supply unit that supplies a plurality of surfaces of the object to be inspected onto an optical scanning line of the irradiation unit; and a detection unit that receives light from the surface to be inspected of the object to be inspected. The irradiation unit limiting unit limits the length of the optical scanning line of the irradiation unit in a predetermined cross section according to the length of the inspection area of the inspection object.

The specific irradiation unit limiting means includes an irradiation angle switching means for irradiating the irradiation angle of the irradiation means to an angle according to the length of the region to be inspected of the plurality of inspection objects, and the plurality of irradiation targets. An irradiation light shielding means for shielding the optical scanning line area of the irradiation means other than an angle corresponding to the length of the inspection area of the inspection object is disclosed.

[0017]

In the present invention, it is provided at a position conjugate with the irradiation position on the surface to be inspected of the inspection object, and it is incident on the light receiving portion of the detecting means according to the length of the inspection area of the plurality of inspection objects. Since it is provided with a light receiving unit limiting means for limiting the length of light in a predetermined cross section, the inspection area of the inspection object is scanned regardless of the size of the inspection object such as a reticle, a mask, or a pellicle. By selecting the length of the incident light of the light receiving portion in a predetermined cross section, it is possible to detect a defect such as a foreign substance with a constant S / N ratio.

Specifically, the light-receiving section limiting means is provided at a position conjugate with the irradiation position on the surface to be inspected of the inspection object, and has a slit length corresponding to the length of the surface to be inspected of the inspection object. The number of slits provided is switched and selected.

By switching and selecting some slits having slit lengths corresponding to the length of the surface to be inspected of the object to be inspected, scattered light (stray light) from the end facet 1B is blocked in a 5-inch reticle, for example. Therefore, it is possible to detect a defect such as a foreign matter with a constant S / N regardless of the reticle size.

Further, according to the present invention, since the reticle of the reticle is provided with the irradiation section limiting means for limiting the optical scanning line width of the irradiation means according to the length of the surface to be inspected of a plurality of objects to be inspected. By selecting the length d of the scanning line LR according to the size, it is possible to detect a defect such as a foreign substance with a constant S / N ratio regardless of the size of an object to be inspected such as a reticle, a mask or a pellicle.

Specific irradiation unit limiting means include irradiation angle switching means for irradiating the irradiation angle of the irradiation means to an angle according to the lengths of the surfaces to be inspected of a plurality of inspection objects, and a plurality of inspection objects. There is an irradiation light shielding unit that shields the optical scanning line region of the irradiation unit other than the angle corresponding to the length of the surface to be inspected.

As the irradiation angle switching means, for example, a deflection angle range of a scanner which emits a fan-shaped optical scanning line is set as follows.
For example, the width of the 6-inch reticle and the width of the 5-inch reticle are selected to match each other.

Further, as the irradiation light shielding means, for example,
An optical switching element is provided in the optical path between the light source and the scanner, and the light from the light source is turned on / off by the switching element when outside the predetermined range, and the optical scanning area of the scanner is adjusted.

As the supply means for supplying the surfaces of a plurality of objects to be inspected having different sizes onto the optical scanning line of the irradiation means, a rotary plate having a uniform height of the surface to be inspected as in the embodiment described later. In addition to those with individual reticles placed on top,
It may be an object to be inspected that has a constant height of the surface to be inspected and is sequentially supplied, and it also includes means for supplying the material in a belt conveyor type.

[0025]

FIG. 1 is an explanatory view showing a main part of a first embodiment of the present invention. The basic structure of the embodiment of the present invention is the same as that of FIG. 5, and the same members are designated by the same reference numerals. I am doing it. The light receiving system of FIG. 5, that is, the light receiving lens 12, the light shielding plate 15, the slit 16,
This is a configuration of a portion including a detector 13 and an output 14.

Through the light receiving lens 12, two switchable light shield plates 20 and 21 are provided on a plane conjugate with the scanning line LR. The scanning lines LR are provided on the light shielding plates 20 and 21, respectively.
Direction (scan line L on a plane conjugate with scan line LR)
Slits 22 and 23 are provided in the length direction of R), and the light shielding plates 20 and 21 are provided with slits 22 and 23 in a direction conjugate with the scanning line LR, respectively. Can be switched by moving in the direction of arrow 24.

When both the light blocking plates 20 and 21 are inserted in the optical path 25, only the light information on the scanning line LR (that is, the scattered light from the foreign matter) enters the detector 13.

FIG. 2 is an explanatory view showing a state of inspecting the 6-inch reticle 2. A light shielding plate 20 is inserted between the light receiving lens 12 and the detector 13. The length of the slit 22 is a point L so that light from the entire scanning line LR enters the detector 13.
A point L'which is conjugate with and a point R'which is conjugate with the point R are defined as both ends.

FIG. 3 is an explanatory view showing a state of inspecting the 5-inch reticle 1. A light shielding plate 21 is inserted between the light receiving lens 12 and the detector 13. With respect to the scanning line LR, the length of the slit 23 is a point conjugate with the point P'and a point conjugate with the point Q so that the slit 13 enters only the range of the length R'of the scanning line width PQ actually required. Both ends are Q '.

Therefore, the end face 1L of the 5-inch reticle 1
Since the light from 1R and 1R is blocked by the light blocking plate 21, as described above, even if the end surface of the 5-inch reticle 1 shines over the entire circumference, the light from the end surface IL or IR does not reach the detector 13. ,
Do not fit. That is, a plane conjugate with the scanning line LR is used as the cross section of the incident light to the light receiving lens 12, and the length of the incident light is limited by the light shielding plate 21 within this cross section.

The switching of the shading plates 20 and 21 may be performed in synchronization with the 180 ° rotational drive of the drive unit 5 of FIG. 5, or the input of 5 inch size or 6 inch size is input from an input means such as a keyboard or a switch. At this time, the drive unit 5 may be driven and the light blocking plates 20 and 21 may be switched.

Next, a second embodiment of the present invention will be described.
In this embodiment, when scanning the 6-inch reticle 2 in the deflection angle range of the scanner 8 according to the reticle size, the scan is performed from the point L to the point R so that the 5-inch reticle 1 can be scanned.
In case of, switching is performed so that scanning is performed from point P to point Q.

Further, FIG. 4 is an explanatory view showing the constitution of the third embodiment of the present invention. As shown in the figure, by providing an optical switching element 30 such as an AOM (acousto-optic modulator) between the light source 7 and the scanner 8, a shutter function for turning on / off the AOM transmitted light 31 is provided, and the scanner 8 The transmitted light 31 may be turned on / off according to the deflection, and the scanning line length on the reticle may be switched from D to D ′.

Incidentally, FIG. 4 shows only a part different from the structure of FIG. In the embodiment of FIG. 4, the length of the slit 16 of the light shielding plate 15 may be the desired length of the scanning line LR. Further, both the switching of the light shielding plate 15 and the adjustment of the length of the scanning line LR may be performed.

[0035]

As described above, the present invention is provided at a position conjugate with the irradiation position on the surface to be inspected of the inspection object, and the detection means of the detection means is provided in accordance with the length of the inspection area of the plurality of inspection objects. The light receiving unit limiting means is provided for limiting the length of the incident light on the light receiving unit in a predetermined cross section.

Specifically, some slits are provided at a position conjugate with the irradiation position on the surface to be inspected of the inspection object, and the slits having a slit length corresponding to the length of the surface to be inspected of the inspection object are switched. Therefore, the surface to be inspected of the object to be inspected is scanned irrespective of the size of the object to be inspected such as a reticle, a mask, or a pellicle, and the length of the incident light of the light receiving part (the surface to be inspected is not conjugate) It is possible to detect defects such as foreign matter with a constant S / N ratio by selecting (length on the surface).

Further, according to the present invention, there is provided an irradiating section limiting means for limiting the optical scanning line length of the irradiating means according to the widths of the inspected surfaces of a plurality of inspected objects.

Specifically, the irradiation angle switching means for irradiating the irradiation angle of the irradiation means to an angle according to the length of the surface to be inspected of a plurality of inspection objects, and the length of the inspection surface of a plurality of inspection objects. Since the irradiation unit limiting means such as the irradiation light blocking means for blocking the optical scanning line region of the irradiation means other than the angle corresponding to the angle is provided, the length d of the scanning line LR depends on the size of the reticle. Can be selected to detect defects such as foreign matter with a constant S / N ratio regardless of the size of the object to be inspected such as the reticle, mask or pellicle.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a main part of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a state of inspecting a 6-inch reticle.

FIG. 3 is an explanatory diagram showing a state of inspecting a 5-inch reticle.

FIG. 4 is an explanatory diagram showing a configuration of a third exemplary embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a configuration of a conventional defect inspection apparatus.

FIG. 6 is a schematic diagram showing multiple reflected light of a light beam on a side surface of a 5-inch reticle.

[Explanation of symbols]

 20, 21 ... Shading plate, 22, 23 ... Slit, 8 ... Scanner 30 ... Optical switching element

Claims (4)

[Claims] 1. An inspection object for an object to be inspected, such as a surface or a pattern surface of a transfer original plate such as a reticle or a mask used for exposure transfer of a fine pattern onto a photosensitive substrate or a surface of a pellicle mounted on the transfer original plate. A defect inspection apparatus for optically inspecting a surface, comprising: an irradiation unit that irradiates the surface to be inspected with light.
An apparatus comprising: a supply unit that supplies a plurality of surfaces of the object to be inspected having different sizes onto an optical scanning line of the irradiation unit; and a detection unit that receives light from the surface to be inspected of the object to be inspected. Provided at a position substantially conjugate with the irradiation position on the surface to be inspected of the inspection object, and predetermined for incident light to the light receiving unit of the detection means according to the length of the inspection area of the plurality of inspection objects. A defect inspection apparatus comprising a light-receiving section limiting means for limiting the length in cross section. 2. An object to be inspected such as a surface or a pattern surface of a transfer original plate such as a reticle or a mask used for exposure transfer of a fine pattern onto a photosensitive substrate or a surface of a pellicle mounted on the transfer original plate. A defect inspection apparatus for optically inspecting a surface, comprising: an irradiation unit that irradiates the surface to be inspected with light.
An apparatus comprising: a supply unit that supplies a plurality of surfaces of the object to be inspected having different sizes onto an optical scanning line of the irradiation unit; and a detection unit that receives light from the surface to be inspected of the object to be inspected. A defect inspection apparatus comprising: an irradiation unit limiting unit that limits a length of an optical scanning line of the irradiation unit in a predetermined section according to a length of an inspection region of the plurality of inspection objects. . 3. The defect inspection apparatus according to claim 2, wherein the irradiation section limiting unit sets an irradiation angle of the irradiation unit to an angle according to a length of an inspection area of the plurality of inspection objects. A defect inspection apparatus characterized in that it is irradiation angle switching means for irradiation. 4. The defect inspection apparatus according to claim 2, wherein the irradiation unit limiting means has an optical scanning line of the irradiation means other than an angle corresponding to a length of an inspection region of the plurality of inspection objects. A defect inspection apparatus, which is irradiation light blocking means for blocking an area.