JP3768029B2 - Pattern defect repair device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
This invention relates to a pattern missing OchiiOsamu positive device, more particularly LCD (Liquid Crystal Display) or a PDP (plasma display) pattern defect correction device so as to correct the defects of the substrate formed on the transparent electrode of flat panel displays such as .
[0002]
[Prior art]
Flat display panels such as LCDs and PDPs have recently become larger and higher in definition. Along with this, the widths of the substrate electrode patterns constituting these are becoming increasingly narrower, and the probability of occurrence of defects is increasing. Such a defect includes a so-called open defect in which the pattern of the substrate is disconnected and a so-called short defect in which the patterns are short-circuited.
[0003]
Conventionally, an inspection apparatus has been used to detect such a defect and correct the defective portion. Conventional inspection apparatuses are typically used in combination with a bright-field optical system and a comparative inspection method using the repeatability of wiring patterns.
[0004]
FIG. 7 is a diagram showing a conventional reflective bright field optical system. In FIG. 7, the light from the illumination light source 1 is reflected by the dichroic mirror 2, condensed by the objective lens 3, and irradiated on the object 4. A reflected image from the object 4 is picked up by the CCD element 5 through the objective lens 3 and the dichroic mirror 2, and the color and density of the object 4 are observed. FIG. 7 shows a reflective bright-field optical system, but there is also a transmissive type in which the illumination light source 1 is disposed below the object 4 and a transmission image of the object 4 is captured by the CCD element 5.
[0005]
FIG. 8 is a diagram for explaining the comparative inspection method. The comparison inspection method is a method in which the brightness level of the reflected light of the object 4 is compared with the brightness pattern of the object 4 adjacent to the object 4, and a mismatched portion is determined as a defect. For example the pattern pitch p, when the luminance signal as shown in FIG. 8 (a) is obtained, when the inspection pixel pixel n, the luminance of the luminance value C (n) and the pixel of the pixel n (n + p) difference value between the value C (n + p) is determined to be in disagreement when more than a certain threshold value as shown in Figure 8 (b).
[0006]
[Problems to be solved by the invention]
In comparison inspection method described above, Razz Do If sufficient contrast is obtained between the defective portion and the normal portion, when combined with bright field optics, the application range for inspection of a short circuit or an open or foreign matter metal wires Limited.
[0007]
On the other hand, the electrode pattern constituting the LCD panel includes a transparent electrode (hereinafter referred to as ITO) in addition to the metal. Usually, a bright-field optical system cannot obtain sufficient contrast for detecting ITO defects, and is difficult to detect at present. In addition, there is a device for determining short circuit or open by electrical inspection, but the detailed position of the defective part cannot be specified, and the operator often finds the defective part by visual inspection when correcting it.
[0008]
Therefore, in order to detect a defect of a transparent object, the following optical system has been conventionally considered.
[0009]
A single wavelength light such as a laser is applied to observe diffracted light and interference fringes. In this case, the wavelength of the laser must be selected depending on the film thickness of the transparent object, which is not suitable when the film thickness varies or the type of the panel changes.
[0010]
When a multi-layered object has a pattern of metal or the like in the lower layer of the transparent object, light having a wavelength band in which the transmittance of the transparent object is the lowest and the reflectance of the lower metal pattern is the highest is observed. In this case, when the film thickness of the transparent object changes, the transmittance also changes. Therefore, it is not suitable when the film thickness varies or the type of the panel changes.
[0011]
In an object having a multilayer structure, when a metal and a transparent object are in the same layer, the contrast is increased by utilizing the fluorescence characteristics of the metal. In this case, it is effective when the metal has fluorescence characteristics.
[0012]
As described above, the three methods described above have a problem that the application range is limited.
[0013]
Another object of the invention is to be detected defects clear pattern was difficult to detect optically, provide a pattern defect correction device capable of correcting.
[0014]
[Means for Solving the Problems]
Pattern defect repairing apparatus according to the present invention is a pattern defect correcting device for correcting the defects of the pattern formed on the substrate, and the differential interference optical system for extracting a differential interference image image of the pattern, the pattern A bright field optical system for obtaining a bright field image, a switching means for selecting any one of a differential interference optical system and a bright field optical system, and a switching means selected by the switching means An image pickup means for picking up an image obtained from the optical system, and a laser light source for irradiating the defect site picked up by the image pickup means with laser light for correction .
[0015]
Here, the differential interference type optical system includes an objective lens provided on the optical axis of the imaging means, a Wollaston prism, an illumination light source, and a polarizer for converting light from the illumination light source into linearly polarized light and guiding it to the optical axis. When, viewed including the analyzer for guiding the imaging means by interference with the incident light reflected light from the pattern, switching means, and at least Wollaston prism and the analyzer is retracted from the optical axis of the imaging means from the differential interference optical system Switch to a bright-field optical system .
[0016]
Good Mashiku further image processing means for detecting a defective portion by processing an image signal output from the imaging means to control the laser light source irradiates a laser beam to the defect site detected by the image processing means And control means for correcting .
[0017]
Preferably, the image processing means registers in advance an area to be inspected for a pattern , compares the image data in the pre-registered area of the captured image data with the adjacent image data, and detects defects. inspect.
Further preferably, the control unit, when modified obtained by the image processing unit width is greater than the pre-registered modified width you fixed in pre-registered correction range.
[0018]
Or good Mashiku the pattern in the case of transparent is selected differential interference optical system by the switching means, if the pattern is not transparent bright field optics by the switching means is selected.
[0019]
Also preferably, the laser light source, correct the defect site and emits a laser beam having a wavelength corresponding to the type of the defect site.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a diagram showing a differential interference optical system according to an embodiment of the present invention. In FIG. 1, the differential interference optical system 10 includes an illumination light source 1, a dichroic mirror 2, an objective lens 3, a polarizer 8, a Wollaston prism 6, and an analyzer 7. Illumination light from the illumination light source 1 enters the polarizer 8 to become linearly polarized light, is reflected by the dichroic mirror 2, passes through the Wollaston prism 6 and the objective lens 3, and is divided into two parallel lights to be an object. 4 is incident. The two lights are linearly polarized light whose vibration directions are orthogonal to each other, and the distance between the two lights is less than the resolution of the objective lens 3. These two lights are reflected by the object 4 and pass through the objective lens 3 and the Wollaston prism 6 to return to one light again. However, since the vibration directions are orthogonal to each other, they do not interfere with each other. After passing through 2, the analyzer 7 is used for interference. This interference image represents the phase gradient (inclination) of the object 4 in light and dark, and becomes brighter at an inclined part, for example, at the boundary of the object 4, and darker at a flat part.
[0021]
FIG. 2A is an observation image by a bright-field optical system, and FIG. 2B is a diagram showing an observation image by a differential interference optical system. In FIG. 2 (a), the hatched portion is an image of the object 4, the luminance sectional view of the portion of line A is shown in FIG. 2 (c), and the height data is shown in FIG. 2 (d). When the portion of the line A is seen in the bright field type optical system, the luminance is lower than the other portions as shown in FIG. 2A, whereas the portion of the line A is shown in the differential interference type optical system. , The height of the object 4 changes as shown in FIG. That is, only the boundary portion becomes bright and the flat portion becomes dark. In the embodiment of the present invention, this property is used to observe the boundary line of a transparent object, and a portion that does not match the normal pattern is detected as a defect.
[0022]
FIG. 3 is a diagram showing an example of a pattern registered according to an embodiment of the present invention, and FIG. 4 is a diagram showing a state of detection processing.
[0023]
In order to detect the position of the pattern to be inspected on the image, the position detection pattern (1) shown in FIG. 3 is registered in the image processing apparatus 20. At the time of inspection, this position detection pattern (1) is searched on the image, and the pattern from the center is the inspection object. Next, the inspection areas (2) and (3) are registered with reference to the center position of the position detection pattern (1). During the inspection, the inside of the registered inspection area is inspected.
[0024]
If a plurality of position detection patterns are registered at this time, even if there is a defect in the position detection pattern, positioning can be performed accurately by using another position detection pattern.
[0025]
Next, a detection processing operation according to an embodiment of the present invention will be described. A position detection pattern (1) is searched from the differential interference image captured by the CCD camera 5. The detection position (4) in FIG. 4 (a) represents the center of the searched position detection pattern (1), and pre-registered inspection areas (2) and (3) are set based on the detection position (4). To do.
[0026]
For the pixels in the set inspection areas (2) and (3), the luminance data of each pixel is compared with the luminance data of a pixel separated from the pixel by the pitch p of the object, and a mismatched portion is detected. . As a result, it is compared with the internal data of masters (5) and (6) in FIG.
[0027]
The comparison of luminance data between pixels may be a comparison within a frame or a comparison between frames. Furthermore, if the comparison pitch p is obtained by image processing, it is not necessary to input numerical values.
[0028]
In the line A of FIG. 4A, the hatched portion in the cross-sectional view shown in FIG. 4B is inconsistent, and it is detected that a short defect exists in the upper electrode as shown in FIG. 4C. In FIG. 4C, the target panel has a multilayer structure, and an insulating film is formed between the lower electrode and the upper electrode. When capturing an image from the CCD camera 5, the images were captured and added several times and averaged to obtain an input image in order to eliminate the pseudo defect wiring due to noise.
[0029]
FIG. 5 is a diagram showing another embodiment of the present invention. This embodiment has a YAG laser optical system for defect correction and an optical system for image observation. In FIG. 5, the optical system is configured to be switchable between a differential interference type optical system and a bright field type optical system by a revolver. For example, a differential interference optical system is selected for a defect of a transparent object, and a bright-field optical system is selected for an object such as a metal that has a sufficient contrast of a defect portion. The differential interference optical system includes an objective lens 3, a Wollaston prism 6, and an analyzer 7, and the bright field optical system includes an objective lens 9. When the differential interference type optical system is selected by the revolver, the objective lens 3, the Wollaston prism 6 and the analyzer 7 are inserted into the optical path. When the bright field type optical system is selected, only the objective lens 9 is used in the optical path. Inserted inside.
[0030]
Furthermore, a YAG laser controller 11 and a multi-wavelength YAG laser 12 are provided to correct defects. The host computer 30 receives the defect detection result from the image processing apparatus 20 and drives the multi-wavelength YAG laser 12 by the YAG laser controller 11 to correct the defect. The reason why the multi-wavelength YAG laser 12 is used is that the laser wavelength used differs depending on the type of defect.
[0031]
FIG. 6 is a diagram illustrating an example in which foreign matter is attached on the electrode. If there is a foreign substance on the lower electrode as shown in FIG. 6C, the hatched portion in the cross-sectional view shown in FIG. Is done.
[0032]
When there is a short defect as shown in FIG. 4, the short defect is removed by the fourth harmonic from the multi-wavelength YAG laser 12, and when there is a foreign substance as shown in FIG. Foreign matter is removed by the fundamental wave from the wavelength YAG laser 12.
[0033]
In order to prevent the normal part from being accidentally damaged when the foreign matter is removed by the fundamental wave from the multi-wavelength YAG laser 12, the correction width (7) (8) for each inspection area as shown in FIG. Can be corrected with the registered correction width when the correction width obtained by image processing is larger than the registered correction width.
[0034]
【The invention's effect】
As described above, according to the present invention, the differential interference image having no dependency on the film thickness of the pattern formed on the substrate is extracted and imaged by the differential interference optical system, and the captured image signal is obtained. Since the defect part is detected by processing, the differential interference image shows the inclination of the object in light and dark, and stable defect detection is possible without being affected by variations in film thickness. .
[0035]
More preferably, since the optical system that can be irradiated with the laser and the optical system that is used for the detection result are mounted, the defect correction can be easily automated. Furthermore, since a multi-wavelength laser light source is used, a correction laser can be selected according to the defect. Furthermore, since the differential interference image and the bright field image can be switched, an image suitable for the inspection can be selected.
[Brief description of the drawings]
FIG. 1 is a diagram showing a differential interference optical system according to an embodiment of the present invention.
FIG. 2 is a diagram showing an observation image by a bright-field optical system and an observation image by a differential interference optical system.
FIG. 3 is a diagram showing an example of a pattern registered according to an embodiment of the present invention.
FIG. 4 is a diagram showing a state of detection processing according to an embodiment of the present invention.
FIG. 5 is a diagram showing another embodiment of the present invention.
FIG. 6 is a diagram illustrating another example of detection processing.
FIG. 7 is a diagram showing a conventional reflective bright-field optical system.
FIG. 8 is a diagram for explaining a conventional comparative inspection method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Illumination light source 2, 13 Dichroic mirror 3, 9 Objective lens 4 Object 5 CCD camera 6 Wollaston prism 7 Analyzer 8 Polarizer 10 Differential interference type optical system 11 YAG laser controller 12 Multiwavelength YAG laser 20 Image processing apparatus 30 Host computer

Claims (6)

A pattern defect correcting device for correcting a defect of a pattern formed on a substrate,
A differential interference optical system for extracting a differential interference image image of the pattern,
A bright field optical system for obtaining a bright field image of the pattern;
Switching means for selecting one of the differential interference optical system and the bright field optical system;
Imaging means for capturing an image obtained from the optical system selected by the switching means;
A laser light source for irradiating and correcting a defect site imaged by the imaging means with a laser beam ;
The differential interference optical system includes an objective lens provided on the optical axis of the imaging means, a Wollaston prism, an illumination light source, and a polarizer for guiding light from the illumination light source to the optical axis as linearly polarized light. And an analyzer for guiding reflected light from the pattern to the imaging means,
The pattern defect correction apparatus according to claim 1 , wherein the switching means switches at least the Wollaston prism and the analyzer from the optical axis of the imaging means to the bright field optical system from the differential interference optical system . Furthermore, image processing means for processing the image signal output from the imaging means to detect a defective part;
Controlling the laser light source, characterized by comprising the detected defective portion and a control means for modifying irradiated with laser light by the image processing means, the pattern defect correction apparatus of claim 1. The image processing unit registers an area to be inspected of the pattern in advance, and compares image data of the pre-registered area with adjacent image data among image data captured by the imaging unit. and and detecting a defect, the pattern defect correction apparatus of claim 2. Wherein if correction range determined by said image processing means is greater than a pre-registered correction range is characterized in that fixed in the pre-registered correction range, claim 2 or claim 3 The pattern defect correction apparatus described in 1. The differential interference optical system is selected by the switching means when the pattern is transparent, and the bright-field optical system is selected by the switching means when the pattern is not transparent. The pattern defect correction apparatus according to any one of claims 1 to 4. The pattern defect correction according to any one of claims 1 to 5, wherein the laser light source corrects the defect portion by emitting laser light having a wavelength corresponding to a type of the defect portion. apparatus.

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