JP2012189567A - Pattern defect detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pattern defect detection device that detects a fluorescent image, a diffusion light image, and a reflection light image of a substrate formed by laminating dry films so as to easily detect various defects occurring in an exposure process.SOLUTION: The pattern defect detection device includes a light source 11 for generating and emitting light, a scan mirror 14 for scanning a substrate 20 with the light emitted by the light source 11, a fluorescent light image detection unit 17 for detecting the image of fluorescent light emitted by the substrate 20, and a diffusion light image detection unit 19 for detecting the image of diffusion light diffused by the substrate 20.

Description

  The present invention relates to a pattern defect detection apparatus.

  The printed circuit board is manufactured by forming the plating thickness to a certain height by copper plating, laminating the dry film, removing a part of the dry film through the exposure and development processes, and opening the copper portion of the open part. A method in which a circuit is formed by peeling a dry film after etching a plating layer is mainly used.

  The conventional method for manufacturing a printed circuit board using a dry film as an etching resist includes the possibility of various defects occurring during the formation of a pattern. Examples include damage and contamination of the mask film, scratches on the dry film, foreign matter on the dry film, lifting due to reduced adhesion between the dry film and the substrate, lifting due to foreign matter between the dry film and the substrate, and the like.

  The defects generated in the exposure process lead to damage of the circuit pattern of the substrate by the development and etching processes.

  Therefore, the circuit pattern on the substrate can be prevented from being damaged by detecting and removing various defects as described above in the exposure process.

  In connection with this, conventionally, an automatic optical detection device can be used as a detection device for detecting a pattern defect of a printed circuit board, but the automatic optical detection device is suitable for images having a large difference in reflectivity. There is a problem that it is difficult to use in an exposure process in which the difference in reflectivity between the exposed layer and the non-exposed layer and the many causative substances (foreign matter, contamination, etc.) is not large.

  Furthermore, the diffuse reflection effect that occurs between the exposed layer and the non-exposed layer makes it more difficult to obtain a good quality image and makes it difficult to detect defects.

  The present invention has been derived to solve the above-described problems, and further detects a fluorescent image, a scattered light image, and a reflected light image of a substrate on which a dry film is laminated, and performs an exposure process. It is an object of the present invention to provide a pattern defect detection apparatus that can easily detect various defects that occur.

  According to the present invention as described above, a light source that generates and emits light, a scan mirror that scans the light emitted from the light source onto a substrate, and a fluorescence image detection unit that detects a fluorescence image that is fluorescent on the substrate. And a scattered light image detector for detecting a scattered light image scattered by the substrate.

  The light source of the present invention generates and emits light having a wavelength of 500 to 600 nm.

  The light source of the present invention is characterized by generating and emitting light having a wavelength of 594 nm.

  In addition, the present invention further includes a reflected light image detection unit that detects a reflected light image reflected from the substrate.

  Further, the present invention converts the fluorescence image detected by the fluorescence image detection unit into a digital fluorescence image and stores it, and converts the scattered light image detected by the scattered light image detection unit into a digital scattered light image and stores it. And a detection image processing unit for displaying the fluorescence image and the scattered light image stored in response to a user request.

  The detection image processing unit according to the present invention is characterized in that the digital fluorescence image and the scattered light image are binarized and stored.

  The detection image processing unit of the present invention includes a first analog-digital converter that converts a fluorescence image detected by the fluorescence image detection unit into a digital fluorescence image, and a fluorescence image converted by the first analog-digital converter. , A second analog-digital converter for converting the scattered light image detected by the scattered light image detector into a digital scattered light image, and the scattered light image converted by the second analog-digital converter A second memory for storing the image, a sign for displaying the fluorescent image and the scattered light image, and a fluorescent image stored in the first memory and stored in the second memory according to a user's request And a controller for outputting a scattered light image to the indicator.

  Further, the light emitted from the light source of the present invention is allowed to pass toward the scan mirror, and when the fluorescence generated by the substrate is incident through the scan mirror, it is reflected by the fluorescence image detection unit. Further includes a dichroic mirror.

  In addition, the present invention further includes a fluorescent filter that is positioned in front of the fluorescent image detection unit and allows the fluorescence formed on the substrate to pass therethrough.

  The features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.

  Prior to the detailed description of the invention, the terms and words used in the specification and claims should not be construed in a normal and lexicographic sense, and the inventor shall best understand his invention. It should be construed as meanings and concepts in accordance with the technical idea of the present invention in accordance with the principle that the concept of terms can be appropriately defined to describe the method.

  According to the present invention as described above, it is possible to perform high-quality image measurement on an exposure circuit pattern film whose change in reflectivity is not large.

  Further, according to the present invention, it becomes possible to measure an exposure circuit pattern film image in which the change in reflectivity is not large at a high speed.

  Further, according to the present invention, it becomes possible to measure the defect state of the copper plating layer under the dry film with the exposure circuit pattern.

  In addition, according to the present invention, it is possible to simultaneously measure a fluorescence image, a scattered light image, and a reflected light image by using three photodetectors simultaneously.

  In addition, according to the present invention, it is possible to measure an image of a substance in which a difference in reflectivity is not large and a scattered image is difficult due to a large amount of scattered light.

It is a block diagram of the pattern defect detection apparatus by 1st Example of this invention. It is a graph which shows the change of the light absorbency before and behind exposure of a dry film. It is a photograph which shows the fluorescence image detected by the fluorescence image detection part. It is a photograph which shows the scattered light image detected by the scattered light image detection part. It is a block diagram of the pattern defect detection apparatus by 2nd Example of this invention. FIG. 4 is a detailed block configuration diagram of a detection image processing unit in FIGS. 1 and 3.

  Objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description and preferred embodiments with reference to the accompanying drawings. In this specification, it should be noted that when adding reference numerals to the components of each drawing, the same components are given the same number as much as possible even if they are shown in different drawings. I must. Further, in describing the present invention, when it is determined that a specific description of the related art related to the present invention may obscure the gist of the present invention, a detailed description thereof will be omitted.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a block diagram of a pattern defect detection apparatus according to a first embodiment of the present invention.

  Referring to FIG. 1, a pattern defect detection apparatus according to a first embodiment of the present invention includes a light source 11, an automatic focus adjustment unit 12, a dichroic mirror 13, a scan mirror 14, a first condenser lens 15, and a fluorescence. A filter 16, a fluorescence image detection unit 17, a second condenser lens 18, a scattered light image detection unit 19, and a detection image processing unit 30 are provided.

  The light source 11 is a laser light source. For example, a semiconductor laser beam such as He—Ne is used, and the wavelength is preferably 500 to 700 nm, and most preferably 594 nm.

  Generally, a light source used in the exposure process is a UV light source having a wavelength band of about 350 nm to 400 nm, and the dry film exposed to the UV light source has a large increase in absorbance in the 600 nm region as shown in FIG. This is because the film is doped with a chemical substance so that a color change is caused by the UV light source.

  Therefore, in the present invention, a laser having a wavelength near 600 nm, which is a region band where the absorbance change before and after exposure is large, is used as the light source 11.

  Next, the automatic focus adjustment unit 12 is composed of at least two or more lenses, and the lens provided toward the light source 11 is moved or the lens provided from the light source 11 is moved away, The focus of the scanning light scanned onto the substrate 20 by the scan mirror 14 is adjusted so that a high-quality image is detected by the fluorescent image detection unit 17 and the scattered light image detection unit 19.

  Such an automatic focus adjustment unit 12 is driven by an automatic focus adjustment control device (not shown) to perform focus adjustment.

  The dichroic mirror 13 passes incident light emitted from the light source 11 and incident on the substrate 20, and reflects reflected light including fluorescence incident from the substrate 20 to the fluorescent image detection unit 17. .

  As described above, the dichroic mirror 13 functions so as to be different from the incident light incident from the light source 11 and the reflected light including the fluorescence incident from the substrate 20, and the reflected light including the fluorescence is changed. It changes so that it may go to the fluorescence image detection part 17 instead of the said light source 11. FIG.

  Meanwhile, the scan mirror 14 scans the substrate 20 with incident light emitted from the light source 11 and incident thereon.

  At this time, the scan mirror 14 scans the incident light emitted from the light source 11 and incident thereon by a zigzag raster method.

  Such a scan mirror 14 may be a galvano mirror, a polygon mirror, a resonant mirror, an AOD (acoustic optical deflector), an EOD (electric optical deflector), or the like.

  The first condenser lens 15 is located between the scan mirror 14 and the substrate 20 and condenses the light emitted from the light source 11 on the target substrate 20. As such a first condenser lens 15, a convex lens whose both surfaces are normally convex is used.

  Next, the fluorescent filter 16 is for blocking the reflected light from the reflected light including the fluorescent light incident from the substrate 20 and allowing the fluorescent light to pass through, and is positioned on the front side of the fluorescent image detecting unit 17.

  Therefore, when the fluorescent filter 16 is removed, a reflected light image is formed on the fluorescent image detection unit 17 via the dichroic mirror 13, and the fluorescent image detection unit 17 can detect the reflected light image.

  On the other hand, the second condenser lens 18 allows the scattered light emitted from the light source 11 and scattered by the substrate 20 to be condensed on the scattered light image detection unit 19.

  The scattered light image detection unit 19 detects and outputs a scattered light image from the scattered light incident through the second condenser lens 18.

  Such a scattered light image detection unit 19 is positioned obliquely with respect to the substrate 20, thereby easily recognizing scattered light generated by a step formed by the dry film pattern of the substrate 20. be able to.

  The board | substrate 20 utilized for the above pattern defect detection apparatuses is a printed circuit board, a ceramic substrate, etc.

  For such printed circuit boards and ceramic substrates, a copper plating layer is formed on the insulating layer by copper plating to a certain height, and after the dry film is laminated, a part of the dry film is removed through an exposure and development process and then opened. It is the board | substrate of the state which etched the copper plating layer of the made part.

  Accordingly, as shown in FIG. 3A, the fluorescent image detector 17 detects and outputs a fluorescent fluorescent image generated by the incident light on the dry film of the substrate 20, and outputs the scattered light image detector. As shown in FIG. 3B, 19 detects and outputs the scattered light image from the scattered light in which the incident light is scattered by the step of the pattern formed on the dry film of the substrate 20.

  In the fluorescent image of FIG. 3A detected in this way, a defect of the dry film can be detected, and in the scattered light image of FIG. 3B, foreign matter inside the dry film can be detected.

  Meanwhile, the detection image processing unit 30 converts the analog fluorescence image and the analog scattered light image detected by the fluorescence image detection unit 17 and the scattered light image detection unit 19 into a digital fluorescence image and a digital scattered light image, and binarizes them. Save it later.

  If necessary, the detection image processing unit 30 displays the stored fluorescence image or scattered light image when the user desires to view the stored fluorescence image or scattered light image.

  The detection of the pattern using the fluorescence detection described above shows an excellent effect when there is a foreign matter such as an etching residue on the dry film.

  However, when detecting defects in the upper layer of the circuit pattern, pattern detection with higher performance can be performed by using detection with reflected light in combination.

  FIG. 4 is a block diagram of a pattern defect detection apparatus according to a second preferred embodiment of the present invention.

  Referring to FIG. 4, a pattern defect detection apparatus according to a second preferred embodiment of the present invention includes a light source 11, an automatic focus adjustment unit 12, a dichroic mirror 13, a scan mirror 14, a first condenser lens 15, A fluorescent filter 16, a fluorescent image detection unit 17, a second condenser lens 18, a scattered light image detection unit 19, a semi-transmissive reflective film 21, a reflected light image detection unit 22, and a detection image processing unit 30; It is equipped with.

  Here, since the light source 11 to the scattered light image detection unit 19 are the same as those in the first embodiment, detailed description thereof is omitted, and the semi-transmissive reflective film 21, the reflected light image detection unit 22, and the detection image processing unit are omitted. 30 will be described in detail.

  The semi-transmissive reflective film 21 allows a part of the reflected light including the fluorescence incident on the substrate 20 from the light source to be reflected, and reflects a part thereof.

  Meanwhile, the reflected light image detection unit 22 detects and outputs a reflected light image from the reflected light reflected from the semi-transmissive reflective film 21.

  Of course, the fluorescent filter 16 may be removed so that the fluorescent image detector 17 detects the reflected light image. However, if the translucent reflective film 21 and the reflected light image detector 22 are provided, the fluorescent image is detected. In addition, the reflected light image can be further detected, which is convenient.

  As described above, when the pattern defect detection apparatus according to the second preferred embodiment of the present invention further includes the reflected light image detection unit 22, the detected image processing unit 30 detects the analog reflected light detected by the reflected light image detection unit 22. The image is converted into a digital reflected light image, binarized, and stored.

  The detected image processing unit 30 displays the stored reflected light image when requested by the user.

  FIG. 5 is a detailed block diagram of the detection image processing unit in FIGS. 1 and 3.

  Referring to FIG. 5, the detection image processing unit of FIGS. 1 and 3 includes first to third analog-digital converters 31 to 33, first to third binarizers 34 to 36, and first to third. 3 memories 37 to 39, a controller 40, and an indicator 41 are included.

  The first analog-digital converter 31 converts the analog fluorescence image detected by the fluorescence image detection unit 17 into a digital fluorescence image and outputs the digital fluorescence image.

  The second analog-digital converter 32 converts the analog scattered light image detected by the scattered light image detection unit 19 into a digital scattered light image and outputs the digital scattered light image.

  The third analog-digital converter 33 converts the analog reflected light image detected by the reflected light image detector 22 into a digital reflected light image and outputs the digital reflected light image.

  Next, the first binarizer 34 binarizes and outputs the fluorescence image converted by the first analog-digital converter 31.

  The second binarizer 35 binarizes and outputs the scattered light image converted by the second analog-digital converter 32.

  Next, the third binarizer 36 binarizes and outputs the reflected light image changed by the third analog-digital converter 33.

  As described above, when binarization is performed on a fluorescent image, scattered light image, or reflected light image, black and white can be clearly confirmed, the amount of data can be minimized, and data processing is easy. become.

  Meanwhile, the first memory 37 stores the fluorescence image binarized by the first binarizer 34.

  The second memory 38 stores the scattered light image binarized by the second binarizer 35.

  Next, the third memory 39 stores the reflected light image binarized by the third binarizer 36. Of course, the first to third memories 37 to 39 may be formed in one memory instead of separate memories as described above.

  The controller 40 controls the internal components of the detection image processing unit, reads out the images stored in the first to third memories 37 to 39 according to a user's request, and supplies them to the indicator 41. Output.

  The indicator 41 displays the binarized and stored fluorescence image, scattered light image, or reflected light image output from the controller 40.

  As described above, the detection image processing unit 30 binarizes the data using the binarizers 34 to 36. However, the binarizers 34 to 36 are not provided, and the data is displayed in a color image. It may be processed.

  Although the preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the specific embodiments described above, and the present invention is not deviated from the scope of the present invention claimed in the claims. It is obvious that various modifications can be made by persons having ordinary knowledge in the technical field to which the invention belongs, and such modifications should not be individually understood from the technical idea of the present invention. Let's go.

  The present invention can be applied to a pattern defect detection apparatus that can easily detect various defects generated in an exposure process.

DESCRIPTION OF SYMBOLS 11 Light source 12 Automatic focus adjustment part 13 Dichroic mirror 14 Scan mirror 15 1st condensing lens 16 Fluorescence filter 17 Fluorescence image detection part 18 2nd condensing lens 19 Scattered light image detection part 20 Substrate 21 Semi-transmissive reflective film 22 Reflected light Image detection unit 30 Detection image processing unit 31 to 33 Analog to digital converter 34 to 36 Binarization unit 37 to 39 Memory 40 Controller 41 Indicator

Claims (9)

A light source that generates and emits light;
A scan mirror that scans the substrate with light emitted from the light source;
A fluorescent image detection unit for detecting a fluorescent image fluorescent with the substrate;
A scattered light image detector for detecting a scattered light image scattered by the substrate;
A pattern defect detection apparatus including:   The pattern defect detection apparatus according to claim 1, wherein the light source generates and emits light having a wavelength of 500 to 600 nm.   The pattern defect detection apparatus according to claim 1, wherein the light source generates and emits light having a wavelength of 594 nm.   The pattern defect detection apparatus according to claim 1, further comprising a reflected light image detection unit that detects a reflected light image reflected from the substrate.   The fluorescent image detected by the fluorescent image detection unit is converted into a digital fluorescent image and stored. The scattered light image detected by the scattered light image detection unit is converted into a digital scattered light image and stored. The pattern defect detection apparatus according to claim 1, further comprising a detection image processing unit that displays a fluorescence image and a scattered light image stored in response.   The pattern defect detection apparatus according to claim 5, wherein the detection image processing unit binarizes and stores the digital fluorescent image and the scattered light image. The detection image processing unit
A first analog-digital converter that converts a fluorescent image detected by the fluorescent image detection unit into a digital fluorescent image;
A first memory for storing the fluorescence image converted by the first analog-digital converter;
A second analog-digital converter that converts the scattered light image detected by the scattered light image detection unit into a digital scattered light image;
A second memory for storing the scattered light image converted by the second analog-digital converter;
A sign for displaying the fluorescent image and the scattered light image;
A controller for outputting a fluorescent image stored in the first memory and a scattered light image stored in the second memory to the indicator according to a user's request;
The pattern defect detection apparatus according to claim 5, comprising:   A dichroic mirror that allows the light emitted from the light source to pass toward the scan mirror and reflects the fluorescence generated by the substrate through the scan mirror to the fluorescence image detection unit; The pattern defect detection apparatus according to claim 1.   The pattern defect detection apparatus according to claim 1, further comprising a fluorescence filter that is positioned in front of the fluorescence image detection unit and allows fluorescence formed on the substrate to pass therethrough.