JP4474904B2 - Periodic pattern unevenness inspection device - Google Patents

Description

  The present invention relates to an unevenness inspection apparatus for products having a periodic pattern.

  In the conventional periodic pattern unevenness inspection, a transmittance image is captured using coaxial transmission illumination or planar illumination (see, for example, Patent Documents 1 and 2), and the intensity (brightness) of light in each image is determined. This is a method of visually recognizing the uneven portion and the normal portion. 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.

The known literature is described below.
JP 2002-148210 A JP 2002-350361 A

  SUMMARY OF THE INVENTION In view of the above-described problems of the prior art, the present invention provides a periodic pattern unevenness inspection apparatus capable of imaging and detecting a periodic pattern, for example, black matrix unevenness, stably and with high accuracy. Objective.

The invention according to claim 1 of the present invention is an inspection apparatus that inspects unevenness of a periodic pattern of a substrate to be inspected,
An imaging unit including an imaging side parallel optical system parallel to the optical axis of the inspection apparatus, and having means for capturing an image;
An XY stage having a means for mounting the substrate to be inspected, recognizing the position, and driving means in the X-axis and Y-axis directions;
A plurality of light sources having an illumination side parallel optical system and capable of individually lighting by illuminating obliquely transmitted light on the inspection target substrate,
Each of the light sources can be individually rotated with the vertical direction of the optical axis of the inspection apparatus, the horizontal direction of the XY stage, and the optical axis of the illumination side parallel optical system as a rotation axis. A left-right rotation drive unit;
The imaging unit, an XY stage, a plurality of light sources, and a plurality of up / down / left / right rotation driving units are managed, and a processing unit including means for sequentially processing a process for inspecting periodic pattern unevenness is provided.
A periodic pattern unevenness inspection apparatus that images diffracted light in a periodic pattern, which is generated by illuminating obliquely transmitted light.

In the first aspect of the present invention, the diffracted light in the periodic pattern is captured by obliquely transmitted illumination, thereby imaging a subtle variation of the periodic pattern, for example, the black matrix. That is, there is an advantage that the present invention can be performed with two components of the light amplitude and the phase of the new light similar to the conventional one from only one component of the intensity (brightness) of the light due to the amplitude of the conventional light. In the diffraction of light, strong transmitted light is formed in a specific direction in the normal part, and in the uneven part, diffracted light is not emitted only in the specific direction, and variously in various directions according to the pattern shape and pitch interval. Diffracted light is generated with the intensity of. This difference is utilized in the present invention.
In addition, by installing a plurality of obliquely transmissive illuminations and switching the illumination, it is possible to illuminate from various directions and to adapt to unevenness having various directions.

  In claim 3, by installing a plurality of obliquely transmissive illuminations and switching the illumination, illumination from various directions is possible, and it is possible to adapt to unevenness having various directions.

According to the inspection apparatus of the present invention as described above, it is possible to detect only the irregularity of the periodic pattern black matrix stably and with high accuracy.
Furthermore, since the original image itself is an image in which unevenness is emphasized, the use as an unevenness monitoring device is also effective.

  FIG. 1 is a conceptual diagram showing a functional configuration of a periodic pattern unevenness inspection apparatus of the present invention. As shown in FIG. 1, the oblique transmission illumination unit 10, the XY stage unit 20 capable of transmission illumination, the imaging unit 30 for imaging, the captured image is enhanced, the unevenness portion is determined, and further enhancement is performed. The processing unit 40 has a function of displaying the displayed image so that a person can easily recognize unevenness.

In the oblique transmission illumination unit 10, the vertical direction of the optical axis of the inspection apparatus, the horizontal direction of the XY stage unit 20, and the vertical direction of rotation that can be rotated about the optical axis of the illumination side parallel optical system 11. Illumination of the illumination side parallel optical system 11 is provided at the tip of the drive unit 12, and illumination from various angles and directions is possible. In other words, the oblique transmission illumination unit 10 can set the parallel optical system 11 and transmission illumination from various angles and directions. Furthermore, a plurality of vertical and horizontal rotation drive units and illuminations are arranged, and the lighting of the illumination can be switched (change of the point light source), the distance from the inspection target substrate, or the incident angle and direction of the illumination light can be switched. .

  In the XY stage unit 20, the inspection target substrate is placed at a predetermined position of the XY stage unit. The XY stage unit has a measurement function, recognizes the position, and superimposes the optical axis of the apparatus on the inspection start position of the inspection target substrate. Using the means for driving in the X-axis and Y-axis directions, the XY stage is driven in the X-axis and Y-axis directions according to a preset operation procedure.

The imaging unit 30 includes an imaging-side parallel optical system 31 parallel to the optical axis, and shares functions such as a means for capturing an image, for example, a camera with a CCD, image data conversion, data storage and transmission.

  The processing unit 40 manages the imaging unit, the XY stage, and the transmitted illumination unit, and comprehensively manages means for sequentially processing the inspection process of the periodic pattern unevenness. Further, the processing unit 40 receives image data from the imaging unit 30, extracts and compares the features of the image according to a predetermined data processing procedure, calculates the difference, and determines pass / fail. The means (flow diagram) for sequentially processing the inspection process for periodic pattern unevenness is shown in FIG. The flow diagram is sequentially processed from the start to the end (in order from 1 to 23).

  In the inspection apparatus for inspecting the periodic pattern unevenness provided with the above-described means, the periodic pattern unevenness inspection characterized in that it images diffracted light in the periodic pattern generated by illuminating obliquely transmitted light Device. In the normal part of the periodic pattern, the shape and pitch of the slit part (or opening part) are constant, so that they interfere with each other, and strong diffracted light is generated in a certain direction. In the uneven part, the slit part (or opening part). Since the shape / pitch becomes unstable, diffracted light is generated with various intensities in various directions according to the shape / pitch.

  In the periodic pattern unevenness inspection apparatus configured as described above, the light emitted from the oblique transmission illumination unit 10 is diffracted at the opening of the inspection target substrate 50 of the black matrix of the periodic pattern, and the diffracted light. Is captured by the imaging unit 30 as an image. When the incident angle is smaller than 90 °, the observation environment is changed, and the difference in the shape and pitch of the slit (or opening) is enhanced, and the difference in diffracted light is further enhanced by the illumination that gradually changes the phase. The

  The diffracted light diffracted by the substrate to be inspected 50 causes a change in the diffraction angle due to subtle fluctuations in the black matrix, so that the image captured by the imaging unit 30 has uneven portions due to fluctuations in the black matrix. The image is emphasized. Furthermore, by using a parallel optical system for the oblique transmission illumination unit 10 and the imaging unit 30, an image in which fluctuations of diffracted light are more accurately emphasized is captured.

  In addition, by sequentially lighting a plurality of installed lights, it is possible to obtain an optimal image for unevenness having various directions.

  In this manner, the unevenness image captured by the imaging unit 30 is subjected to unevenness portion extraction processing and determination processing by the processing unit 40. By displaying the determined position and level of the uneven portion at the same time as the uneven image on the processing unit 40, the use for unevenness monitoring is also effective.

It is a conceptual diagram which shows the function structure of the periodic pattern nonuniformity inspection apparatus of this invention. It is a flowchart which processes sequentially the process of the test | inspection of the periodic pattern nonuniformity of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Oblique transmission illumination part 11 ... Illumination side parallel optical system 12 ... Vertical / horizontal rotation operation part 20 ... XY stage part 30 ... Imaging part 31 ... Imaging side parallel optical system 40 ... Processing part 50 ... Inspection object board | substrate

Claims (1)

An inspection apparatus for inspecting unevenness of a periodic pattern of a substrate to be inspected,
An imaging unit including an imaging side parallel optical system parallel to the optical axis of the inspection apparatus, and having means for capturing an image;
An XY stage having a means for placing the substrate to be inspected, recognizing the position, and driving means in the X-axis and Y-axis directions;
A plurality of light sources having an illumination side parallel optical system and capable of individually lighting by illuminating obliquely transmitted light on the inspection target substrate,
Each of the light sources can be individually rotated with the vertical direction of the optical axis of the inspection apparatus, the horizontal direction of the XY stage, and the optical axis of the illumination side parallel optical system as a rotation axis. A left-right rotation drive unit;
The imaging unit, an XY stage, a plurality of light sources, and a plurality of up / down / left / right rotation driving units are managed, and a processing unit including means for sequentially processing a process for inspecting periodic pattern unevenness is provided.
A periodic pattern unevenness inspection apparatus that images diffracted light in a periodic pattern, which is generated by illuminating obliquely transmitted light.

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