JP2014095617A - Device for measuring pattern and method for measuring pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for measuring a pattern capable of easily and accurately measuring a distance between patterns of a measurement object.SOLUTION: A device 1 for measuring a pattern photographs patterns A, B of a retardation film 20 disposed on a measurement table 40 by cameras 31, 32 together with reference patterns 11, 12, respectively. An information processing device 60 calculates a positional deviation D1 between the reference pattern 11 and the pattern A and a positional deviation D2 between the reference pattern 12 and the pattern B by using an actual distance per unit pixel, from an image 131 photographed by the camera 31 and an image 132 photographed by the camera 32, and calculates a distance Lp between the patterns A and B from the positional deviations D1, D2 and from a known distance L between the reference patterns 11, 12.

Description

  The present invention relates to a pattern measuring apparatus and a pattern measuring method for measuring a pattern distance of an object.

  When manufacturing retardation films for liquid crystal panels, glass masks for semiconductor manufacturing, and the like, the dimensions of the patterns provided on these films may be measured for quality control and the like. As an apparatus for performing such measurement, there is known an apparatus for measuring a dimension of a sample while relatively moving the sample and an optical system of a camera using a moving stage (Patent Document 1, etc.). .

Japanese Utility Model Publication No. 4-61010

  However, in Patent Document 1, the moving distance of the moving stage is measured for measurement. However, in such a case, there is a problem that the measurement result depends on the accuracy of the device that measures the moving distance.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a pattern measuring apparatus and the like that can easily and accurately measure a pattern distance.

  A first invention for achieving the above-described object is a pattern measuring apparatus for measuring a pattern distance of an object having a pattern, and includes a first reference pattern and a second reference pattern formed at a predetermined interval. , A first imaging device, a second imaging device, and an information processing device, wherein the information processing device includes a first pattern of the object together with the first reference pattern. And the second image obtained by the second imaging device capturing the second pattern of the object together with the second reference pattern, and the first image of the object. A pattern measuring apparatus that calculates a distance between a pattern and a second pattern.

  According to the first invention, an object having a pattern is arranged such that patterns at both ends whose distance is to be measured are positioned in the vicinity of the first reference pattern and the second reference pattern whose distance is known. Images can be taken by the first imaging device and the second imaging device, and the distance between patterns can be measured using these images. Even if it is a large measuring object, it is not necessary to image over the full length between patterns, and it can image in a short time and can measure distance easily. Also, the device can be inexpensive.

The information processing apparatus uses a real distance per pixel to calculate a first interval between the first reference pattern and the first pattern of the object from the first image and the second image. A positional deviation, a second positional deviation between the second reference pattern and the second pattern of the object is calculated, and the predetermined interval, the first positional deviation, and the second positional deviation are used. It is desirable to calculate the distance between the first pattern and the second pattern of the object.
In this case, since the position of the pattern of the target object and the position of the reference pattern may be shifted, the distance between the patterns of the target object can be calculated with high accuracy regardless of the accuracy of arranging the target object.

In addition, a photomask can be used as the reference pattern.
Thereby, when forming a pattern on a target object using a photomask, it can be investigated whether the shift | offset | difference at the time of pattern formation had arisen. In addition, the accuracy of the reference pattern is reliable.

  A second invention is a pattern measurement method for measuring a pattern distance of an object having a pattern, and the first image of the object is imaged together with the first reference pattern by the first imaging device. Imaging the second pattern of the object together with the second reference pattern formed at a predetermined interval from the first reference pattern by the second imaging device; A first image obtained by imaging the first pattern of the object together with the first reference pattern, and a second pattern of the object obtained by the second imaging apparatus together with the second reference pattern. Calculating a distance between the first pattern and the second pattern of the object based on a second image obtained by imaging the object.

  According to the present invention, it is possible to provide a pattern measuring apparatus or the like that can easily and accurately measure the distance of a pattern.

The figure which shows the pattern measurement apparatus 1 The figure which shows the example of the phase difference film 20 The figure shown about the measurement by the pattern measurement apparatus 1 The figure which shows the example of the image imaged with the cameras 31 and 32 The figure which shows typically the relationship between the polarizing direction of the polarizing film 15, the polarizing filter 36, and the orientation direction of orientation pattern 23a, 23b. Diagram showing the relationship between the wavelength of illumination light and retardation The figure which shows the example of the processing flow of the information processing apparatus 60 The figure which shows another example of a pattern measuring device

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description and the accompanying drawings, the same reference numerals are given to components having substantially the same functional configuration, and redundant description is omitted.

[1. Configuration of Pattern Measuring Device 1]
First, the pattern measurement apparatus of this embodiment will be described with reference to FIG.

  FIG. 1 is a diagram showing an outline of the pattern measuring apparatus 1. The pattern measuring apparatus 1 includes a measurement table 40, transfer stages 30, 50, cameras 31, 32 (first and second imaging devices), illumination devices 51, 52, an information processing device 60, and the like. The pattern measuring apparatus 1 captures an object having a pattern with cameras 31 and 32 and measures a distance between predetermined patterns by image processing.

  The measurement table 40 is a rectangular table on which objects are arranged. An opening 41 is provided in the center of the measurement table 40 along the long side direction of the table, and the transparent glass plate 10 is fitted into the opening 41. As the glass plate 10, a glass plate having no change in length due to thermal expansion is used. A reference pattern serving as a reference for length measurement is formed on the glass plate 10. This reference pattern will be described later.

  Gate-shaped support portions 43 and 43 are provided at both ends of the measurement table 40 in the long side direction of the table. Above the measurement table 40, the transfer stage 30 is bridged between the support portions 43 and 43.

  Cameras 31 and 32 are attached to the transfer stage 30. The cameras 31 and 32 can be moved in the long side direction of the table along the transfer stage 30 by driving means such as a motor.

  The cameras 31 and 32 are imaging devices that capture the reference pattern together with the pattern of the object. An adapter 35 is attached to the light receiving portions of the cameras 31 and 32. The adapter 35 incorporates a polarizing filter and a phase difference plate, which will be described later.

  Illumination devices 51 and 52 are disposed below the measurement table 40. The illuminating devices 51 and 52 are attached to the transfer stage 50 arranged along the long side direction of the table and irradiate illumination light upward toward the opening 41. The illuminating devices 51 and 52 can be moved in the long side direction of the table along the transport stage 50 by driving means such as a motor.

  As a light source of the illumination devices 51 and 52, for example, a light source that generates infrared light having a wavelength of 780 nm or more is used. Examples of such a light source include an LED lamp that is a single wavelength light source having a peak wavelength in the infrared region. Therefore, it is desirable that the cameras 31 and 32 have sensitivity in the wavelength region including the wavelength of the light source, and the measurement table 40 is surrounded by a dark room.

  The information processing device 60 controls the movement and imaging of the cameras 31 and 32 and the movement and lighting of the lighting devices 51 and 52, acquires images captured by the cameras 31 and 32, performs image processing, and performs object processing. Measure the distance between the predetermined patterns. The information processing apparatus 60 can be realized by a general computer including a control unit, a storage unit, a communication unit, a display unit, and the like.

[2. Retardation film 20]
In the present embodiment, the object to be measured is a retardation film. FIG. 2 is a view showing the retardation film 20. FIG. 2A shows a pattern in the orientation direction of the retardation film 20. FIG. 2B shows a cross section in the thickness direction of the retardation film 20.

This retardation film 20 is an FPR (Film) used in 3D display devices and the like.
Patterned Retarder) film. In the FPR film, as shown in FIG. 2A, two patterns 23a and 23b whose orientation directions (indicated by arrows in the drawing) are orthogonal to each other are alternately repeated along the film longitudinal direction.

  As shown in FIG. 2B, in this retardation film 20, a retardation layer 23 having alignment direction patterns 23 a and 23 b is provided on a film substrate 27. A protective film 28 is provided on the upper surface of the retardation film 20 in order to prevent damage in the manufacturing process. The protective film 28 is a transparent resin film such as a polyester film, and is peeled off when the retardation film 20 is used for a liquid crystal panel or the like. In some cases, the protective film 28 may be further provided on the lower surface of the retardation film 20.

[3. Measurement by pattern measuring apparatus 1]
Next, the measurement of the pattern distance by the pattern measuring apparatus 1 will be described. FIG. 3A is a diagram showing the arrangement of the retardation film 20 and the like during measurement by the pattern measuring apparatus 1 along the table short side direction. FIG. 3B is a diagram showing a configuration in the long side direction of the table along the line aa in FIG.

  As shown in FIGS. 3A and 3B, the retardation film 20 is disposed on the glass plate 10 when measuring the distance of the pattern. Further, a pressure glass 42 is disposed on the retardation film 20 to fix the retardation film 20. However, the method of fixing the position of the retardation film 20 is not limited to this.

  Reference patterns 11 and 12 (first and second reference patterns) are provided near the center of the glass plate 10 in the table short side direction. These reference patterns 11 and 12 are provided with a predetermined interval L in the table long side direction. The interval L is determined in advance according to the measurement standard of the retardation film 20 so as to be a reference when measuring the distance of the pattern of the retardation film 20, and the value is a storage unit of the information processing device 60. Is remembered.

  The reference patterns 11 and 12 can be formed, for example, by applying a pattern that blocks the illumination light from the illumination devices 51 and 52 to the surface of the glass plate 10. In the present embodiment, the reference pattern 11 is rectangular, but the shape, size, arrangement, and the like can be determined as appropriate.

  Moreover, as shown to Fig.3 (a), the side of the reference patterns 11 and 12 of the glass plate 10 is slightly depressed, and the polarizing film 15 is arrange | positioned here. The depth of the dent is determined to be approximately the thickness of the polarizing film 15.

  A polarizing filter 36 and a phase difference plate 37 are disposed in the adapter 35. The polarization direction of the polarizing filter 36 is set so as to be orthogonal to the polarization direction of the polarizing film 15 and has a crossed Nicols arrangement. Further, the polarization direction of the polarizing film 15 or the polarizing filter 36 forms an angle of 20 ° or more and 70 ° or less with the orientation direction of one pattern of the retardation film 20.

  The retardation film 20 is illuminated by the illumination devices 51 and 52 from the glass plate 10 side, and is imaged together with the reference patterns 11 and 12 by the cameras 31 and 32, respectively.

[4. Images captured by cameras 31, 32]
FIG. 4 is a diagram schematically illustrating an example of an image captured by the cameras 31 and 32. In FIG. 4, an image 131 (first image) captured by the camera 31 is shown on the left, and an image 132 (second image) captured by the camera 32 is shown on the right.

  As shown in FIG. 4, in each of the images 131 and 132, the two alignment direction patterns 23 a and 23 b of the retardation film 20 appear alternately as light and dark patterns. In addition to the light and dark pattern, the reference pattern 11 is displayed as a dark portion in the image 131 and the reference pattern 12 is displayed as a dark portion in the image 132, respectively.

  Here, the alignment direction patterns 23a and 23b appear as light and dark patterns due to the difference in the alignment directions.

  This will be described with reference to FIG. FIG. 5 schematically shows the relationship between the polarization direction of the polarizing film 15, the polarizing filter 36, and the orientation direction of the patterns 23a and 23b. As described above, the polarization directions of the polarizing film 15 and the polarizing filter 36 and the alignment directions of the patterns 23a and 23b are orthogonal to each other, and the alignment direction of the pattern 23a is 20 ° or more and 70 ° or less with respect to the polarization direction of the polarizing film 15. An angle θ in the range of.

  In this embodiment, the illumination devices 51 and 52 emit illumination light in a randomly polarized state, and this light is transmitted through the polarization film 15 to become linearly polarized light 71 having a polarization direction corresponding to the polarization direction. . This light becomes elliptically polarized light 72 and 73 by passing through the regions of the patterns 23 a and 23 b of the retardation film 20.

  The elliptically polarized light 72 and 73 are transmitted through the regions of the patterns 23a and 23b, so that components in different directions are dominant. In this embodiment, the polarization direction component of the polarizing film 15 is dominant in the elliptically polarized light 72, and the polarization direction component of the polarizing filter 36 is dominant in the elliptically polarized light 73.

  Therefore, a difference in the amount of light transmitted through the polarizing filter 36 and incident on the cameras 31 and 32 can be made between these elliptically polarized lights 72 and 73. In the present embodiment, the amount of light transmitted through the polarizing filter 36 by the elliptically polarized light 73 passing through the region of the pattern 23b is larger, and the amount of light transmitted by the elliptically polarized light 72 passing through the region of the pattern 23a is smaller. Therefore, as shown in FIG. 4, the patterns 23a and 23b appear as light and dark patterns on the image.

  As shown in FIG. 3B, the polarizing film 15 is not provided between the reference patterns 11 and 12, but in the images 131 and 132 in FIG. 4, this place is irrespective of the difference between the patterns 23a and 23b. The brightness is comparable. In this place, the illumination light in the random polarization state directly transmits the patterns 23a and 23b of the retardation film 20, but the random polarization state does not change as a whole even if a phase difference occurs due to the orientation direction of the patterns 23a and 23b. This is because there is no difference in the amount of light transmitted through the polarizing filter 36.

  By the way, in this embodiment, as shown in FIG.2 (b), the protective film 28 is provided in the phase difference film 20, Thereby, retardation arises in the light which permeate | transmits the phase difference film 20, and the position The contrast of the patterns 23a and 23b on the images 131 and 132 may be difficult to distinguish due to the influence of the phase difference.

  For example, as shown in FIG. 5, a phase difference is generated in the elliptically polarized light 72 as indicated by 23a 'to become an elliptically polarized light 72', and similarly, a phase difference is generated in the elliptically polarized light 73 as indicated by 23b '. If it becomes 73 ′, there is no difference in the amount of light transmitted through the polarizing filter 36.

  In order to prevent this, in this embodiment, infrared light is used as the light source of the illumination devices 51 and 52 as described above.

  That is, FIG. 6A is a graph schematically showing the difference in retardation caused by retardation with the wavelength of the light source, where the vertical axis is the phase difference and the horizontal axis is the wavelength of the light source. In addition, the influence of retardation decreases as the wavelength of illumination light increases. In the present embodiment, infrared light having a large wavelength is used as the light source of illumination light, thereby preventing the contrast of the patterns 23a and 23b from being lowered due to the retardation.

  In FIG. 6B, the vertical axis represents the ratio of the amount of illumination light that has passed through the regions of the patterns 23a and 23b and the horizontal axis represents the magnitude of the retardation, and these relationships are represented by the wavelength of the light source. It is the graph typically shown for every (430, 850, 940 nm).

  As shown by the chain line (the wavelength of the light source is 850 nm) and the solid line (the wavelength of the light source is 980 nm), the change in the light amount ratio due to the retardation difference (unevenness) becomes more gradual as the wavelength of the illumination light increases. As described above, when infrared light is used as the light source of illumination light, it is understood that the influence of retardation unevenness for each region of the protective film 28 is small.

  In addition, in this embodiment, the retardation plate 37 is disposed in the adapter 35 and the orientation direction thereof is adjusted to cancel the influence of the retardation of the remaining protective film 28 slightly. In this way, as shown in FIG. 4, in the images 131 and 132, the contrast of light and dark of the patterns 23a and 23b is increased.

[5. Pattern measurement method]
Next, a method for measuring the distance between predetermined patterns of the retardation film 20 by the pattern measuring apparatus 1 will be described with reference to FIG. FIG. 7 is a diagram illustrating an example of a processing flow of the information processing apparatus 60 at this time.

  In measuring the distance between patterns, the retardation film 20 is disposed on the glass plate 10 of the measurement table 40 of the pattern measuring apparatus 1 as described above. The film length direction of the retardation film 20 is aligned with the long side direction of the table, and a transparent pressing glass 42 is placed on the retardation film 20.

  Next, the information processing device 60 adjusts the positions of the cameras 31 and 32 and the lighting devices 51 and 52. That is, the imaging ranges of the cameras 31 and 32 are matched with the positions of the reference patterns 11 and 12, respectively, and the positions of the illumination devices 51 and 52 are matched with the positions of the cameras 31 and 32, respectively (S101).

  Next, the lighting devices 51 and 52 are turned on by the information processing device 60, and images are captured by the cameras 31 and 32, and the images 131 and 132 described with reference to FIG. 4 are acquired (S102).

  Next, the information processing device 60 performs image processing on the images 131 and 132, and calculates the pattern distance of the retardation film 20 (S103).

  That is, in the image 131 shown in FIG. 4, the number of pixels between the inner end of the predetermined pattern A (first pattern) at one end of the retardation film 20 and the inner end of the reference pattern 11 is calculated. The positional deviation D1 (first positional deviation) between the inner edge of the pattern A and the inner edge of the reference pattern 11 is calculated by multiplying the actual distance per pixel stored in advance in the storage unit. .

  Similarly, in the image 132, the positional deviation D2 between the inner end of the predetermined pattern B (second pattern) at the other end of the retardation film 20 and the inner end of the reference pattern 12 (second). Position deviation).

  Next, the distance Lp between the patterns A and B of the retardation film 20 is calculated by subtracting D1 and D2 from the distance L between the inner ends of the reference patterns 11 and 12 stored in advance in the storage unit. . In the example of FIG. 4, the inner ends of the patterns A and B are inside the inner ends of the reference patterns 11 and 12, but if the inner end of the pattern is outside the inner ends of the reference pattern, the position The distance Lp is calculated by adding the deviations D1 and D2 to the interval L.

  As described above, according to the present embodiment, the retardation film 20 is positioned such that the patterns A and B at both ends whose distances are to be measured are positioned in the vicinity of the reference patterns 11 and 12 formed at the interval L. The distance between the patterns A and B can be measured using the images. Even if it is a large measuring object, it is not necessary to image over the full length between patterns, and it can image in a short time and can measure distance easily. Also, the device can be inexpensive.

  Further, the information processing apparatus uses the actual distance per pixel to set the positional deviations D1 and D2 between the patterns A and B and the reference patterns 11 and 12 and the known interval L between the reference patterns 11 and 12 as described above. Since the distance Lp between the patterns A and B of the retardation film 20 is calculated using the positions of the patterns 23a and 23b of the retardation film 20 and the reference patterns 11 and 12, the retardation film 20 is disposed. The distance between patterns can be calculated with high accuracy regardless of the accuracy with which the data is to be processed.

  However, the present invention is not limited to this. For example, the phase difference film 20 is formed by performing exposure through a photomask having a pattern of a light-shielding portion and a light-transmitting portion corresponding to the patterns 23a and 23b to form the patterns 23a and 23b. Then, using this photomask itself, two patterns of a photomask having a known interval may be used as the reference pattern. Thus, it is possible to examine whether or not a shift during pattern formation has occurred when forming a pattern using a photomask. In addition, the accuracy of the reference pattern is reliable.

  The illumination light may be irradiated from above. For example, as shown in FIG. 8 (a), the bottom of the polarizing film 15 is used as a reflecting plate 10a, and illumination light is applied to the retardation film 20 from the illumination device 51 (52) provided above. The camera 31 (32) receives the light transmitted through the polarizing film 15 and reflected from the reflecting plate 10a, and again transmitted through the polarizing film 15 and the retardation film 20. Even in this case, since the illumination light reflected from the reflecting plate 10a is linearly polarized light similar to the above when it passes through the polarizing film 15, the pattern can be measured in the same manner as described above.

  On the other hand, in the example shown in FIG. 8B, the illumination light incident on the retardation film 20 from the illumination device 51 (52) and the reflected light of the illumination light are placed on the same optical axis using the half mirror 39. Even in this case, the pattern can be measured similarly.

  In addition, in the present embodiment, two cameras, lighting devices, and reference patterns are provided, but the number is not limited to this. For example, it is possible to provide four of these and perform the above measurements in parallel.

  Furthermore, the object for measuring the distance of the pattern is not limited to the retardation film 20 as long as it has a pattern. For example, a photomask having a pattern of a light shielding portion and a light transmitting portion may be used. In this case, the configuration of the polarizing film 15, the polarizing filter 36, the phase difference plate 37, and the like can be omitted. In addition, a light source with a shorter wavelength can be used for the illumination devices 51 and 52 as well.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such examples. It will be apparent to those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea disclosed in the present application, and these naturally belong to the technical scope of the present invention. Understood.

1: Pattern measuring device 10: Glass plate 11, 12: Reference pattern 15: Polarizing film 20: Phase difference film 23a, 23b: Pattern 31, 32: Camera 36: Polarizing filter 40: Measurement table 51, 52: Illuminating device 60: Information processing device

Claims (4)

A pattern measuring apparatus for measuring a pattern distance of an object having a pattern,
A first reference pattern and a second reference pattern formed at a predetermined interval;
A first imaging device and a second imaging device;
An information processing device;
With
The information processing device includes a first image obtained by the first image pickup device picking up the first pattern of the object together with the first reference pattern, and a second image pickup device configured by the second image pickup device. A pattern measuring apparatus that calculates a distance between the first pattern and the second pattern of the object based on a second image obtained by capturing the second pattern of the object together with the pattern. The information processing apparatus includes:
Using the actual distance per pixel, a first misalignment between the first reference pattern and the first pattern of the object from the first image and the second image, the second Calculating a second misalignment between the reference pattern and the second pattern of the object,
2. The pattern according to claim 1, wherein a distance between the first pattern and the second pattern of the object is calculated using the predetermined interval, the first positional deviation, and the second positional deviation. measuring device.   The pattern measuring apparatus according to claim 1, wherein a photomask is used as the reference pattern. A pattern measuring method for measuring a distance of a pattern of an object having a pattern,
A first image of the object is imaged together with a first reference pattern by a first imaging device, and a second pattern of the object is predetermined from the first reference pattern by a second imaging device. Imaging with a second reference pattern formed at intervals;
An information processing device includes a first image obtained by the first image pickup device picking up a first pattern of the object together with the first reference pattern, and a second image pickup device provided with the second reference pattern. Calculating a distance between the first pattern and the second pattern of the object based on a second image obtained by imaging the second pattern of the object;
A pattern measuring method comprising:

Images