JP2007264540A - Inspection device for aperture pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspection device for an aperture pattern which is advantageous in irradiating the entire surface area of a body to be inspected with oblique light of a shallow angle to a deep angle. <P>SOLUTION: When the body 20 to be inspected such as a photomask is mounted on a stage 34 for the inspection device, the top surface of the body 20 to be inspected is exposed above a support member 14 and the bottom surface of the body 20 to be inspected is exposed below the support member 14. Consequently, a large inspection light movable range is obtained by a light source 30 from the shallow angle to the deep angle, so inspection with a high degree of freedom can be performed during transmission/reflection measurement requiring irradiation with oblique light and the body to be inspected can be positioned at the outer peripheral margin part of a plane and at a thickness-directional section part, so inspection over the entire surface except for the outer peripheral margin part of the plane becomes possible and the body to be inspected can accurately be positioned, thereby improving reproducibility of a position. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an opening pattern inspection apparatus.

  In a conventional periodic pattern inspection device, a transmittance image is captured using transmission illumination or plane illumination coaxial with an imaging camera, and the intensity (brightness) of light in each image is compared with that of a nonuniformity portion and a normal portion. It is a method of visually recognizing. For this reason, the difference in light intensity between the uneven part and the normal part is originally small, that is, by devising an intensity difference processing method for images with low contrast, the difference is expanded and the uneven part is extracted and inspected. ing.

  However, in the above-described prior art, in the imaging of the black matrix unevenness of the grid-like periodic pattern, particularly the black matrix unevenness having a large opening, the contrast between the uneven portion and the normal portion cannot be improved, and the intensity difference Even if the processing is devised, there is a problem that the inspection in the case of an image with a low contrast of the original image can only achieve a lower inspection ability than the visual sensory inspection method. The periodic pattern refers to an aggregate of slit patterns having a constant interval (hereinafter referred to as a pitch). For example, a striped periodic pattern in which one pattern is arranged at a predetermined pitch, or an opening. These patterns are a matrix-like periodic pattern in which these patterns are arranged at a predetermined pitch.

  On the other hand, due to the increase in fine display and electronic components with a bright screen, the periodic pattern tends to be miniaturized or the aperture ratio is increased. In the future, there will be a need for an inspection method and apparatus for periodic pattern irregularity inspection for a black matrix having a finer shape and a larger opening. That is, there is a limit in the conventional output with only the intensity (brightness) of the light depending on the amplitude of the light.

  In view of this, a periodic pattern unevenness imaged by an imaging device is provided for the purpose of providing a periodic pattern unevenness inspection device capable of capturing and detecting a periodic pattern, for example, black matrix unevenness stably and with high accuracy. In an inspection apparatus for inspecting unevenness, an imaging side parallel optical system parallel to the inspection object inspection surface, an imaging unit including means for imaging an image, a substrate to be inspected, a position recognition, An XY stage having means for driving in the X-axis and Y-axis directions, a vertical tilt direction of the optical axis and a drive unit for horizontally rotating the optical axis, and an illumination side parallel optical system fixed to the tip of the drive unit Of the periodic pattern including a processing unit that includes means for managing the imaging unit, the XY stage, and the transmission illumination unit, and sequentially processing the inspection process of the irregularity of the periodic pattern. There has been proposed a periodic pattern unevenness inspection apparatus that inspects diffracted light in a periodic pattern, which is an inspection apparatus that inspects a laser beam and that is generated by illuminating obliquely transmitted light (patent) Reference 1).

  In the defect inspection apparatus for products having these periodic patterns, there is a problem that the inspected object is put in and taken out by hand, and dirt easily adheres to a part of the inspected object.

When measuring defects such as photomasks using the light transmission / reflection principle, not only the direction perpendicular to the object to be inspected, but also oblique light from a shallow angle to a deep angle is applied to the entire surface area of the object to be inspected. As shown in FIGS. 6A and 6B, the conventional general inspection apparatus has a problem that the inspection light movable range angle is small.
That is, when the X slide table 2 and the Y slide table 4 are overlapped, the irradiation center position is deep and the inspection light movable range of the irradiation light becomes small, and the original inspection cannot be sufficiently performed.
In FIG. 6 (b), the configuration of FIG. 6 (a) is inverted upside down. In this case, the inspection irradiation light from the lower surface can ensure a sufficient inspection light movable range, but is irradiated from the upper surface. The precession width of the light angle is insufficient as in FIG.
Japanese Patent Laid-Open No. 2-50208 (FIG. 29)

  The present invention has been made in order to solve the above-described problems in the prior art, and its purpose is to detect defects in an object to be inspected such as a photomask using the principle of light transmission / reflection. When inspecting the object to be inspected while moving it to a desired position during measurement, not only in the direction perpendicular to the object to be inspected, but also to irradiate the entire area of the object to be inspected from a shallow angle to a deep angle. Further, it is an object of the present invention to provide an inspection apparatus for an opening pattern that can be stably inspected under predetermined conditions even when inspecting different inspection objects.

  The present invention has been made to solve the above-mentioned problems, and the invention according to claim 1 irradiates the inspection pattern with the inspection light while changing the angle with respect to the surface of the inspection object. An inspection apparatus that inspects the opening pattern by detecting at least one of reflected light reflected by the object to be inspected and light transmitted through the opening pattern, wherein the inspection apparatus is the object to be inspected. An inspection stage that holds a first guide shaft extending in a horizontal plane, a first slider slidably coupled to the first guide shaft, and a horizontal plane. A second guide shaft extending in a direction perpendicular to the first guide shaft and extending in the extending direction is coupled to the first slider, and is slidably coupled to the second guide shaft. Serial characterized in that it comprises a support member for holding the object to be inspected.

  According to a second aspect of the present invention, two first guide shafts are provided so as to be parallel to each other, and the first slider is slidably coupled to the two first guide shafts, Two second guide shafts are provided so as to be parallel to each other, and both ends in the extending direction of the two second guide shafts extend along the first guide shaft of each of the first sliders. It is characterized by being coupled to both ends in the present direction.

According to a third aspect of the present invention, the support member includes a second slider slidably coupled to the second guide shaft, and a frame-shaped cassette holder attached to the second slider. The cassette holder is detachably attached to the inside of the cassette holder and is provided with a cassette provided with a holding portion for the object to be inspected.
According to a fourth aspect of the present invention, the holding unit is provided in the cassette and has an inspection opening in the center, and a frame-shaped mounting unit on which the outer peripheral portion of the object to be inspected is mounted; And an attachment that positions and attaches the object to be inspected, which is provided facing the placement portion and placed on the placement portion, to the placement portion.

The inspection object stage and holder of the present invention are placed on the inspection object such as a photomask, and the inspection light movable range can be increased from a shallow angle to a deep angle, so it is free for transmission and reflection measurement that requires oblique light irradiation. It is possible to perform high-grade inspection, and positioning can be performed on the outer peripheral margin part of the plane of the object to be inspected and the cross section in the thickness direction, making it easy to inspect the entire surface excluding the outer peripheral margin part of the plane. Since the position can be accurately positioned, the reproducibility of the position is improved.
Furthermore, for example, if a cassette prepared in advance is used, it is possible to change from a 6-inch size photomask inspection to a 7-inch size photomask inspection, which improves the versatility of the apparatus.
Further, when placing the object to be inspected on the cassette, since only the planar outer margin part and the outer peripheral surface part are in contact with the cassette, the object to be inspected is very rarely contaminated.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing a positional relationship between an irradiation range of an inspection light source unit and a camera that captures an inspection image in the opening pattern inspection apparatus of the present embodiment.
2A is a top view of the opening pattern inspection apparatus of the present embodiment, and FIG. 2B is a cross-sectional view taken along the line BB of FIG.
3A is a top view of the inspection stage 34 in the opening pattern inspection apparatus of the present embodiment, and FIG. 3B is a sectional view taken along the line BB of FIG.
FIG. 4 is an explanatory diagram of positioning of the inspection object 20.
FIG. 5 is a diagram showing an irradiation range of the inspection light source unit in the inspection apparatus for the opening pattern of the present embodiment.

As shown in FIG. 1, the inspection apparatus 100 irradiates the opening pattern of the inspection object 20 with inspection light while changing the angle with respect to the surface of the inspection object 20 from the light source 30, and is reflected by the inspection object 20. The aperture pattern is inspected by detecting at least one of the reflected light or the transmitted light transmitted through the aperture pattern with the imaging camera 32, and an inspection stage 34 that holds the object 20 to be inspected is provided.
The inspection device 100 has a device base (not shown), and the base plate 10 shown in FIG. 2 is fixed to the device base.
As shown in FIG. 2, the base plate 10 is formed in a rectangular frame shape, and an inspection stage 34 is provided on the inside thereof.
The inspection stage 34 includes a first guide shaft 11, a first slider 12, a second guide shaft 13, and a support member 14.
Two first guide shafts 11 are provided, extend in parallel to each other in a horizontal plane, and both ends of the first guide shafts 11 are coupled to two opposite sides inside the base plate 10.
Two first sliders 12 are provided and slidably coupled to the two first guide shafts 11, respectively.
Two second guide shafts 13 are provided and extend in parallel to each other in a direction orthogonal to the first guide shaft 11 in a horizontal plane, and each second guide shaft 13 has an end in the extending direction thereof. The portions are respectively coupled to both ends of the first slider 12 in the extending direction along the first guide shaft 11.
The support member 14 is slidably coupled to the two second guide shafts 13 and holds the device under test 20.
The support member 14 includes a second slider 1402, a cassette holder 26, and a cassette 21.
Two second sliders 1402 are provided and slidably coupled to the respective second guide shafts 13.
The cassette holder 26 is formed in a rectangular frame shape, and two opposite sides are coupled to two second sliders 1402.

As shown in FIG. 3, the cassette 21 is formed in a rectangular frame shape, and is detachably attached to the inside of the cassette holder 26.
Specifically, when the cassette 21 is inserted inside the cassette holder 26, the cassette fixing screw 25 screwed to one side of the cassette holder 26 is fastened to tighten the front end of the cassette fixing screw 25 and the inner wall of the cassette holder 26. The cassette 21 is configured to be removed by loosening the cassette fixing screw 25.
According to such a configuration, the cassette 21 attached to the cassette holder 26 can be easily exchanged according to the size of the inspection object 20, and inspection can be performed regardless of the size of the inspection object 20. For example, if an inspection object cassette prepared in advance is used, it is possible to change from a 6-inch size photomask inspection to a 7-inch size photomask inspection, which is advantageous in enhancing the versatility of the inspection apparatus 10.

The cassette 21 is provided with a holding portion 2102 for the inspected object 20.
The holding unit 2102 includes a placement unit 36 and an attachment tool 38.
The placement portion 36 is provided inside the cassette 21, and an inspection opening 3602 is provided at the center, and a frame-like placement surface 3604 on which the outer peripheral portion of the inspection target 20 is placed, and a placement surface 3604. And four side surfaces 3606 erected from the periphery.

The mounting tool 38 is provided so as to face the mounting portion 36, and positions and attaches the inspection object 20 placed on the mounting portion 36 to the mounting portion 36.
The attachment 38 includes a protrusion 23 provided on one side surface 3606 of the two opposing side surfaces 3606 of the mounting portion 36 at a distance in the extending direction, and the other of the two opposing side surfaces 3606. And a fixed cam 24 provided on the side surface 3606 of the side surface 3606 so as to face the protrusion 23.
As shown in FIG. 5, when the fixed cam 24 is rotated in a predetermined direction, the cam surface of the fixed cam 24 (24-a) abuts on the side surface of the inspection object 20 and the opposite side surface of the inspection object 20 protrudes. The object to be inspected 20 is positioned and fixed by being applied to 23.
When the fixed cam 24 is rotated in the opposite direction, the cam surface of the fixed cam 24 (24-b) is separated from the side surface of the device under test 20, and the attachment of the device under test 20 is released.
According to such a configuration, the contact portion of the cassette 21 with the device under test 20 is limited to the placement surface 3604, the protrusion 23, and the fixed cam 24. That is, when placing the inspection object 20 on the cassette 21, only the planar outer margin part and the outer peripheral surface part are in contact with the cassette 21, so that the inspection object 20 is hardly contaminated.
The inspected object 20 is transferred to the cassette 21 using a general-purpose handling jig. At this time, as shown in FIG. 2A, the general-purpose handling jig is preliminarily placed in the cassette 21 so that the portion of the general-purpose handling jig for chucking the object 20 to be inspected does not interfere with the cassette 21. A tool escape portion 22 is provided.

The material of the cassette 21 is preferably a resin material or a plastic material in consideration of damage to the object 20 to be inspected. In consideration of measurement by irradiating light, a material that shields or scatters light as much as possible is preferable while avoiding a transparent body.
Similarly, in the fixed cam 24, in consideration of damage to the object 20 to be inspected, a resin material or a plastic material having an antistatic function is preferable for a portion that directly contacts.

It is also possible to digitally specify a desired amount of movement using means for electrically operating the first and second sliders 12 and 1402, and further using means for grasping the current position. Position reproducibility and measurement quantification are also possible.
In this case, as a means for operating the first and second sliders 12 and 1402, a combination of a ball screw and a servo motor or a combination of a ball screw and a stepping motor is generally used. Recently, a linear actuator or the like is also used as an operation positioning means. Can be used.
In addition, as a means for grasping the current positions of the first and second sliders 12 and 1402, an encoder with a built-in motor is generally used, and in addition, an optical scale or the like can be used.

Next, the function and effect will be described.
As shown in FIG. 5, when the inspection object 20 such as a photomask is placed on the inspection apparatus stage 34, the upper surface of the inspection object 20 is exposed above the support member 14, and the lower surface of the inspection object 20 is supported. It will be in the state exposed under the member 14. FIG.
Accordingly, since the inspection light movable range can be increased from a shallow angle to a deep angle by the light source 30, it is possible to perform inspection with a high degree of freedom in transmission / reflection measurement that requires oblique light irradiation. Since positioning is possible at the outer margin part and the cross section in the thickness direction, inspection of the entire surface excluding the outer peripheral margin part of the flat surface is facilitated, and the reproducibility of the position is improved because the object to be inspected can be accurately positioned.
That is, in the conventional apparatus, since the X slide table and the Y slide table overlap, the irradiation center position is deep and the inspection light movable range of the irradiation light with respect to the object to be inspected is small. The inspection apparatus 100 of this form is advantageous because it can ensure a large inspection light movable range of the support member 14.

It is a figure which shows the positional relationship of the camera which image | photographs a test | inspection image with the irradiation range of the test | inspection light source part in the inspection apparatus of the opening pattern of this Embodiment. (A) is a top view of the inspection apparatus for an opening pattern of the present embodiment, and (b) is a cross-sectional view taken along the line BB of (a). (A) is a top view of the inspection stage 34 in the opening pattern inspection apparatus of the present embodiment, and (b) is a cross-sectional view taken along the line BB of (a). It is explanatory drawing of positioning of the to-be-inspected object 20. FIG. It is a figure which shows the irradiation range of the test | inspection light source part in the inspection apparatus of the opening pattern of this Embodiment. (A), (b) is explanatory drawing of a conventional apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... 1st guide shaft, 12 ... 1st slider, 13 ... 2nd guide shaft, 14 ... Support member, 34 ... Inspection stage, 20 ... Test object, 100 ... Inspection apparatus.

Claims (4)

At least one of reflected light reflected by the inspection object and transmitted light transmitted through the opening pattern is irradiated with inspection light while changing the angle with respect to the surface of the inspection object to the opening pattern of the inspection object An inspection device for inspecting the opening pattern by detecting
The inspection apparatus includes an inspection stage for holding the object to be inspected,
The inspection stage is:
A first guide shaft extending in a horizontal plane;
A first slider slidably coupled to the first guide shaft;
A second guide shaft extending in a direction perpendicular to the first guide shaft in a horizontal plane and having an end in the extending direction coupled to the first slider;
A support member that is slidably coupled to the second guide shaft and holds the object to be inspected;
An inspection apparatus for an opening pattern, comprising: Two first guide shafts are provided in parallel to each other, and the first slider is slidably coupled to the two first guide shafts,
Two second guide shafts are provided so as to be parallel to each other, and both ends in the extending direction of the two second guide shafts are along the first guide shafts of the first sliders. Connected to both ends in the extending direction,
The opening pattern inspection apparatus according to claim 1.   The support member is slidably coupled to the second guide shaft, a frame-shaped cassette holder attached to the second slider, and detachably attached to the inside of the cassette holder. 2. The opening pattern inspection apparatus according to claim 1, wherein the opening pattern inspection apparatus is constituted by a cassette which is attached and provided with a holding portion for the object to be inspected. The holding portion is provided in the cassette and has an inspection opening in the center, a frame-like placement portion on which the outer peripheral portion of the object to be inspected is placed, and a front portion that faces the placement portion. 4. The opening pattern inspection apparatus according to claim 3, further comprising an attachment for positioning and attaching the object to be inspected placed on the placement portion to the placement portion.

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