JPH0323948B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a pattern processing method, and particularly to a pattern processing method in an apparatus that optically detects and inspects a pattern.

(2) Technical background For example, a pattern inspection device for circuits formed on printed circuit boards used in microcomputers, etc.
In particular, devices have been developed to automatically inspect patterns. For automatic pattern inspection, the pattern is first read optically, the result is converted into an electrical signal, and this electrical signal is observed by another electrical circuit to inspect for defects. At that time, preprocessing is performed prior to the inspection. The present invention relates to a method for this pretreatment.

(3) Problems with the Prior Art In pattern inspection apparatuses, preprocessing is always performed on detected patterns in order to prevent malfunctions of defect detection circuits. Since the first read pattern itself contains noise and has uneven edges, it is difficult to inspect the read pattern as it is, so preprocessing is performed to eliminate noise and unevenness.

The pattern is visually represented by black and white, with black appearing as a thin and short bar, and black and white electrically representing "1".
and “0”. Especially near the boundaries of the pattern (also called edges), the pattern tends to have uneven parts, so it is desirable to eliminate the uneven parts. Otherwise, the pattern will be detected as defective.

One pattern is shown in FIG. The illustrated pattern is composed of the above-mentioned black bars and white, but the figure schematically shows a sandy background instead of the black bars. Although some of the unevenness on the edge is shown exaggerated on edge 1, similar unevenness also exists on other edges. In the pattern shown in Fig. 1, the unevenness on the edge 1 appears as a defect despite the absence of a defect, but the parts indicated by 2 and 3 in the figure are actually due to poor pattern spacing.
A disconnection defect exists.

Pre-processing the pattern of FIG. 1 according to the prior art results in the pattern shown in FIG. Although it is good that the unevenness of the edge 1 is gone, the patterns are connected in the areas where the pattern spacing is poor.
Also, the disconnected parts will be connected. This preprocessing removes minute defects, but even if the pattern shown in FIG. 2 is inspected, accurate detection will not be possible.

The above phenomenon is caused by the following pretreatment in the conventional method. Referring to FIG. 3, each part indicated by A, B, and C represents a sensor, and the sanded sensors A and B correspond to black 1, or each of the sensors C corresponds to white 0. In the conventional method, when A=B=1, C=1, preprocessing is performed to make all black 1 as shown in FIG. 4, and this operation is performed in four directions. As a result, as mentioned above, the unevenness of the edges was removed, but other minute defects were also removed.

(4) Purpose of the Invention In view of the above-mentioned conventional problems, an object of the present invention is to provide a pattern preprocessing method with high inspection reliability in an apparatus that optically detects and inspects a pattern.

(5) Structure of the Invention According to the present invention, in preprocessing of a binary pattern when optically detecting and inspecting a pattern, the values of adjacent pixels are "0" and "1". , and furthermore, when the value of a pixel located a predetermined number of pixels away from the pixel with the value of "1" and located on the same line is "1", those two pixels are "1"
This is achieved by providing a pattern processing method characterized in that the values of a plurality of pixels sandwiched between pixels are set to "1".

(6) Examples of the invention Embodiments of the present invention will be explained in detail below with reference to the drawings.

In order to prevent this, the inventor removed only the unevenness near the edges in pre-processing, since if the unevenness of the pattern edges is left as is, even if the pattern is good, it may be judged as defective during inspection. However, recognizing that defects other than the edge portion must be left as they are even if they are minute defects, we devised the principle shown in FIGS. 5 and 6. That is, in FIG. 5, sensors A and C each represent white 0, and centers B and D represent black 1. In the figure, black is represented by a sandy background. And sensor A=0 and B=D
If =1, then C=1. The results are shown in FIG. 6, and in the present invention, such sensors are provided in eight directions.

FIG. 7 shows a circuit for realizing the above operation. In the figure, 11 is an inverter, 12 is an inverter, and 12 is an inverter.
13 represents an AND gate, and 13 represents an OR gate.

To explain the above operation with reference to FIG. 8, taking the area near the pattern boundary as an example, a black mark 4 appears outside edge 1, which is the edge of the pattern, and an empty space is generated at the edge. Suppose that there is an unevenness in the part. Applying Figure 5 to this, we find that A outside B is white, and as described above, B
to D are connected in black as in the case of FIG. 6, and there are no irregularities near the boundaries of the pattern.

Next, the disconnected portion 3 will be defined with reference to FIG.
If we apply Fig. 5 to the broken line, since A is not white, there will be no connection from B to D in black, and the broken line will remain white, that is, the broken line itself.

The result of preprocessing the pattern shown in FIG. 1 in this way is schematically shown in FIG. If the sensors shown in Figures 5 and 6 are arranged in eight directions and preprocessed, the part that has entered the edge part 1 in Figure 1 in a cove shape (this part may be mistakenly detected as a defect). ) is preprocessed and embedded as described with reference to FIG. 8, thereby preventing the portion in question from being detected as a defect. In addition,
The recesses other than the above-mentioned cove-shaped portions remain as partially filled recesses, but this does not affect pattern inspection. On the other hand, pattern spacing defects and wire breaks are maintained as they are and inspected.

Note that the minute pattern removal process is possible even if the logic 1 and 0 in the above embodiment are replaced.
The scope of application of the present invention is not limited to the above cases.

(7) Effects of the Invention As explained in detail above, according to the present invention, it is possible to remove only the unevenness near the pattern boundary without removing minute defects, which is highly effective in improving the reliability of pattern inspection. It is.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a pattern, FIG. 2 is a diagram showing the result of preprocessing the pattern in FIG. 1 by a conventional method, FIGS. 3 and 4 are diagrams showing the principle of conventional pattern preprocessing, 5 and 6 are diagrams showing the principle of pattern preprocessing of the present invention, Figure 7 is a diagram showing a circuit for implementing the method of the present invention, and Figures 8 and 9 are diagrams showing the method of the present invention. A diagram showing an example, FIG. 10 is the first
It is a figure which shows the result of preprocessing the pattern of a figure by this invention. 1...Edge part (near the boundary), 2...Poor pattern interval part, 3...Pattern disconnection part, 4...Black pattern, 11...Inverter, 12...AND
Gate, 13...OR gate.

Claims (1)

[Claims] 1. 2. When performing optical pattern detection and inspection.
In the value pattern preprocessing, the values of adjacent pixels are "0" and "1", and the value of a pixel located a predetermined number of pixels away from the pixel with the value "1" and located on the same line is "1", the pattern processing method is characterized in that when the value of the pixels is "1", the values of a plurality of pixels sandwiched between the two pixels "1" are set to "1".