Radiant energy – Photocells; circuits and apparatus – With circuit for evaluating a web – strand – strip – or sheet
Reexamination Certificate
2000-06-15
2003-05-20
Kim, Robert H. (Department: 2882)
Radiant energy
Photocells; circuits and apparatus
With circuit for evaluating a web, strand, strip, or sheet
C250S208100, C356S237500
Reexamination Certificate
active
06566671
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a microscopic defect inspection apparatus and a method thereof, as well as a positional shift or gap calculation circuit therefor, for detecting or inspecting very fine defects, such as very fine or minute foreign substances or matters and/or pattern defects on a subject, for example on substrates, in particular, the substrate which has repetitive patterns thereon, such as a semiconductor wafer, a reticule with phase sifter and a TFT substrate.
Conventional arts relating to a method for inspecting defects on repetitive patterns were already known, for example, in Japanese Patent Laying-Open No. Hei 5-264467 (1993) (Conventional art 1), Japanese Patent Laying-open No. Hei 5-6928 (1993) (Conventional art 2) and Japanese Patent Laying-Open No. Hei 10-74812 (1998) (Conventional art 3).
In those conventional arts 1, 2 and 3, there are described inspection of defects on the repetitive patterns, by detecting the positional shift or gap between video picture inputted and picture delayed by a pitch of the repetitive pattern so as to compensate or correct it. In particular, according to the conventional art 2, in the pattern inspection of detecting two (2) pictures formed to be the same pattern, so as to be compared with after being adjusted in positions thereof, thereby to determine the defects at the portions being inconsistent with each other on those video pictures, there is described that an amount of positional shifts or gaps on the pictures is detected at every predetermined time period, and that compensation or correction of those positional gaps is made dependent upon the amount of positional gaps up to the previous one.
Also, in the conventional art 3, there are described an inspection method for patterns as an object or target for inspection, wherein a video signal is detected from the repetitive patterns to be inspected, so as to produce a statistic video signal of the repetitive pattern therefrom, and then the defects or potential or pseudo-defects lying on the subject pattern are extracted by comparing this statistic video signal produced as a reference to the above-mentioned video signal detected after adjusting the positions thereof; and also an inspection method for the subject, i.e., the patterns to be inspected, wherein the video signal is detected from the repetitive patterns to be inspected, so as to produce a statistic information indicated by a statistic amount of the repetitive pattern from the detection video signal, and then the defects or potential or pseudo-defects lying on the subject pattern are extracted by treating a decision process upon the difference on video, being obtained by adjusting in position and then comparing the video signals of the above-mentioned repetitive patterns with each other, upon the basis of criteria being obtainable from the produced statistic information mentioned above. Further, in the conventional art 3, there is also described that the patterns as the subject are inspected with using an electron pictures thereof.
Further, a conventional art relating to a video picture detection system with using ultraviolet rays is already known in Japanese Patent Laying-Open No. Hei 10-177139 (1998) (Conventional art 4). In this conventional art 4, it comprises correcting mechanisms for primary and higher dimensions on various kinds of aberrations, including aberrations in the longitudinal and horizontal directions of spectrum, spreading over a wide band region from the ultraviolet to far-ultraviolet in the effective wavelength thereof, and there is further described a wide band ultraviolet ray video system, apply both principles of reflection and refraction therein, having a focus lens group composed of a plurality of lenses for providing the high dimensional correction on the video distortion within the same spectrum band or the aberration which causes change of color due to the chromatic aberration, a field lens group having at least two (2) refraction characteristics being different to each other, and further a catadioptric group.
For detecting the defects, such as breaks or short-circuits of lines on the wiring patterns, the picture video must be detected on the patterns as the target for inspection. However, the wiring patterns on semiconductor devices or the like are in a tendency of minimization, and the resolution is short or high on the picture which is obtained through an optical microscope under a visual light rays, therefore it is impossible to analyze the fine or microscopic patterns, then there occurs a necessity of using an optical microscope with using far-ultraviolet ray and/or an electron microscope.
However, in the conventional art 4 mentioned in the above, no consideration was taken on an aspect of enabling detection of the defects and/or foreign substances or matters of the very fine or minute patterns, occurring on the substrate as the target of inspection, on which the patterns are formed.
Also, none of the conventional arts 1, 2 and 3 mentioned above makes consideration on an aspect of enabling to detect the video signal having a high resolution through the optical microscope with using the far-ultraviolet ray.
Further, in a case of using the optical microscope with using far-ultraviolet ray and/or the electron microscope, since there occurs a necessity of detecting the video signal while reducing the size of the pixels, the number of the pixels lying within an area or region to be searched for detection and correction of the position shifts or gaps is enlarged or extended in that instance, the scale of circuitry to execute the video processing for detection and corrections of the position gaps is increased up, and the time necessary for that video processing of detection of the position shift and so on, as well.
However, none of the conventional arts 1, 2 and 3 mentioned above pays consideration on an aspect of small-sizing the circuit scale for performing the video processing of detection and correction of the position shift, nor of shortening the video processing time necessary for detection of the position shift and so on, in particular in the case of using the optical microscope with far-ultraviolet ray and/or the electron microscope.
SUMMARY OF THE INVENTION
An object according to the present invention, for dissolving the problems mentioned above, is to provide a fine defect inspection apparatus and a method thereof, wherein video processing for detection and correction of the position shift can be conducted upon the video signal detected by using the optical microscope with far-ultraviolet ray and/or the electron microscope, in the enlarged search area or region in which the number of the pixels thereof is increased up, thereby being able to perform the inspection with high reliability, but without failing to detect the very fine true defects erroneously.
Also, other object according to the present invention is to provide a fine defect inspection apparatus and a method thereof, wherein the video processing for detection and correction of the position shift can be conducted upon the video signal detected by using the optical microscope with far-ultraviolet ray and/or the electron microscope, at a high speed with high throughput, but without increasing up the circuit scale, thereby being able to perform the inspection with high reliability, but without failing to detect the very fine true defects erroneously.
Also, further other object according to the present invention is to provide a fine defect inspection apparatus and a method thereof, wherein the video signal detected with a high resolving power can be obtained from the optical microscope with far-ultraviolet ray, at high speed and with high resolution, thereby being able to perform the inspection with high reliability and also with high speed, but without failing to detect the very fine true defects erroneously.
Moreover, further other object according to the present invention is to provide a position shift calculation circuit for realizing the detection of the position gaps within the enlarged s
Isobe Mitsunobu
Maeda Shunji
Mizumoto Hisashi
Okabe Takafumi
Yoshida Atsushi
Antonelli Terry Stout & Kraus LLP
Hitachi , Ltd.
Kao G
Kim Robert H.
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