JPH0512410A - Wiring pattern inspecting method - Google Patents

Abstract

PURPOSE:To surely detect the defect of a wiring pattern by extracting the defect on the wiring pattern by subtracting a pattern image, which smoothes a reflected light pattern image, from a fluorescent pattern image. CONSTITUTION:Analog signals are converted by an A/D conversion circuit 7 and a binarization circuit 8, and a negative pattern image is obtained. For the obtained image, black-and-white is inverted/reduced by an inverter circuit 9 and a reduction circuit 10 and further, the image is converted to a positive pattern image by a smoothing circuit 11 and stored in a first memory 12. On the other hand, electric signals are converted by an A/D conversion circuit 7a and a binarization circuit 8a, and a pattern image is obtained and stored in a second memory 14. Next, the pattern image stored in the memory 14 is subtracted from the pattern image stored in the memory 12, the defect of an obtained pattern image is extracted by a defect extraction circuit 19, and the image is outputted from a defect output circuit 20 as the defect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring pattern inspection method, and more particularly to a pattern inspection method for a printed wiring board (hereinafter referred to as a substrate).

[0002]

2. Description of the Related Art In a conventional wiring pattern inspection, a pattern image obtained by detecting reflected light is used as shown in FIG.
There are a reflected light pattern inspection method for detecting defects on wiring and a fluorescent pattern inspection method for detecting defects on wiring from a pattern image obtained by inverting the image obtained by detecting fluorescence shown in FIG. .

First, the reflected light pattern inspection method of FIG. 6 will be described. The inspection device includes an illumination 2 using a halogen lamp or the like as a light source for obtaining reflected light, a camera 6 using a high-sensitivity CCD for detecting reflected light, and the camera 6.
A to convert the analog signal detected from
/ D conversion circuit 7 and binarization circuit 8 for binarizing its output
A memory 17 for storing the binarized signal, a defect extraction circuit 19 for extracting a defect of the pattern image obtained in the memory 17, and a defect output circuit 20 for outputting the defect of the extraction circuit 19. Has been done.

When the wiring pattern as shown in FIG. 2 is inspected by this method, the reflected light pattern image stored in the memory 17 is as shown in FIG. 8 (a). In this figure, it is not possible to detect a defect (defect A in FIG. 4A) short-circuited with the adjacent pattern in the AA cross section of the pattern in FIG. Further, when the binarization level is lowered, the short circuit can be detected, but in this case, the defect (defect D in FIG. 4D) in the DD cross section cannot be detected, and the pattern surface and the substrate surface are not detected. Contrast becomes unstable. on the other hand,
The fluorescence pattern inspection method includes a fluorescence reflection illumination 3 that emits light having a wavelength of 500 to 700 nm, a half mirror 4,
A camera 6 using a high-sensitivity detector having a spectral sensitivity wavelength range of 500 to 700 nm, an A / D conversion circuit 7 for converting an analog signal detected by the camera 6 into a digital signal, and a binarization circuit 8. An inversion circuit 9 for inverting black and white of a binarized pattern image, and a memory 12 for storing the same.
A defect extraction circuit 19 for extracting a defect of the pattern image obtained in the memory 12 and a defect output circuit 20 for outputting the defect are used.

When the pattern shown in FIG. 2 is inspected by this method, the pattern image obtained in the memory 12 is as shown in FIG.
It becomes like (b). In this figure, the pattern A- in FIG.
A short-circuit (defect A in FIG. 4A) in the A section can be detected, but a defect (defect D in FIG. 4D) in which only the upper portion of the pattern in the DD section is missing cannot be detected. In the fluorescence pattern inspection method, since the fluorescence reflection of the base material is detected, the defect on the pattern surface cannot be detected.

[0006]

The above-described conventional pattern inspection method has the following problems. 1) In the reflected light pattern inspection method, a short circuit may not be detected. 2) The fluorescence pattern inspection method cannot detect a chipped defect only in the upper part of the pattern.

The object of the present invention is to solve these problems,
It is an object of the present invention to provide a wiring pattern inspection method capable of surely inspecting a wiring pattern.

[0008]

The structure of the wiring pattern inspection method of the present invention is to detect fluorescent reflected light generated from a substrate of a substrate having a wiring pattern, a resist, or the like to obtain a fluorescent pattern image, and to obtain this fluorescent pattern. From the pattern image obtained by reducing and smoothing the image, the reflected light from the same location as the fluorescence detection pattern of the substrate is detected to obtain a reflected light pattern image, and the pattern image obtained by smoothing the reflected light pattern image is used as the fluorescent light. It is characterized in that a defect on the wiring pattern is extracted by subtracting from the pattern image to obtain a defect pattern image.

[0009]

1 is a block diagram of a defect detection unit according to an embodiment of the present invention. The defect detection unit of this embodiment is
First illumination 2 using a halogen lamp, etc., and a wavelength of 50
The second illumination 3 for fluorescence reflection that generates light of 0 to 700 nm, the half mirror 4, the infrared reflection mirror 5, and the first highly sensitive detector having a spectral sensitivity wavelength range of 500 to 700 nm are used. A camera 6 and an A / D conversion circuit 7 for converting an analog signal detected by the camera 6 into a digital signal,
A binarization circuit 8, an inversion circuit 9 for inverting black and white of a binarized pattern image, a reduction circuit 10 for reducing the inverted pattern image, and a smoothing circuit 1 for smoothing the contour of the pattern image.
1 and a first memory 1 for storing a smoothed pattern image
2 and.

The second camera 1 which is a high-sensitivity CCD camera
3 and an A / D conversion circuit 7a and a binarization circuit 8a for converting an analog signal detected by the camera 13 into a digital signal.
A smoothing circuit 11a that smoothes the contour of the binarized pattern image, a second memory 14 that stores the smoothed pattern image, and a second from the pattern images stored in the first memory 12. A first combining circuit 15 for subtracting the pattern image stored in the memory 14, a third memory 16 for storing the pattern image obtained by this combining circuit 15, and a pattern image obtained by the binarizing circuit 8a. Fourth memory 17 for storing
And a second synthesizing circuit 18 for adding the pattern image stored in the third memory 16 and the pattern image stored in the fourth memory 17, and a defect is extracted from the pattern image obtained by this synthesizing circuit 18. And a defect output circuit 20 for outputting the extracted defect.

Here, it is assumed that the wiring pattern of the substrate 1 shown in FIG. 2 is inspected. On this substrate 1, as shown in FIG. 4, a defect short-circuited with the adjacent pattern in the AA cross section (defect A in FIG. 4A) and a defect broken in the BB cross section (FIG. 4B). Defect B), a residual copper due to insufficient etching in the CC cross section (defect C in FIG. 4C), and a defect only on the pattern in the cross section DD (defect D in FIG. 4D).

The light from the first illumination 2 directly illuminates the inspection surface of the substrate 1, and the light from the second illumination 3 has its direction changed by 90 ° by the half mirror 4 and illuminates the same inspection surface. The fluorescence reflection light reflected from the base material surface of the inspection surface by the second illumination 3 passes through the half mirror 4 and the infrared reflection mirror 5 and enters the first camera 6 to be converted into an analog signal.

This analog signal is converted by the A / D conversion circuit 7 and the binarization circuit 8 to obtain the negative pattern image shown in FIG. 3 (a). The obtained negative pattern image is inverted / reduced in black and white by the inversion circuit 9 and the reduction circuit 10, and is further smoothed by the smoothing circuit 11 in FIG.
Is converted into a positive pattern image shown in FIG.

In the smoothing circuit 11, the reduction circuit 10
As shown in FIG. 5 (a), the pattern image afterward is recognized as a pattern image having an uneven contour due to the effect of the finished state of the pattern shape. The pattern image is converted as shown.

Next, the light reflected from the pattern surface on the inspection surface by the first illumination 2 is reflected by the infrared reflecting mirror 5 to 9
The direction is changed by 0 °, and the second camera 13 enters and is converted into an analog signal. This electric signal is converted by the A / D conversion circuit 7a and the binarization electric circuit 8a, as shown in FIG.
The pattern image shown in (c) is obtained. The obtained pattern image is stored in the fourth memory 17, and the smoothing circuit 11
By a, it is converted into the pattern image shown in FIG.
Stored in the memory 14.

The pattern image stored in the first memory 12 and the pattern image stored in the second memory 14 are divided into the second pattern image from the pattern image stored in the first memory 12 by the first combining circuit 15. The pattern image stored in the memory 14 is subtracted, converted into a pattern image obtained only by the first camera 6 as shown in FIG. 3 (e), and stored in the third memory 16. The pattern image obtained in the third memory 16 and the pattern image obtained in the fourth memory 17 are combined by the second combining circuit 18 to obtain the pattern image shown in FIG. The obtained pattern image is the defect extraction circuit 19
Thus, the defect is extracted and output from the defect output circuit 20 as a defect.

[0017]

As described above, in the wiring pattern inspection method according to the present invention, the defects of the reflected light pattern inspection method and the defects of the fluorescent pattern inspection method are mutually compensated to surely detect the defects on the wiring pattern. There is an effect that can be.

[Brief description of drawings]

FIG. 1 is a block diagram of a defect detection unit according to an embodiment of the present invention.

FIG. 2 is a wiring pattern diagram to be inspected in this embodiment.

3A to 3F are display diagrams showing patterns in each block of the present embodiment.

FIG. 4 is a cross-sectional view of a wiring pattern to be inspected in FIG.

5 is a pattern diagram before and after the smoothing circuit of FIG.

FIG. 6 is a block diagram of a defect detection unit in a conventional reflected light pattern inspection method.

FIG. 7 is a block diagram of a defect detection unit in a conventional fluorescent pattern inspection method.

8A and 8B are pattern diagrams obtained by a reflected light pattern inspection method and a fluorescent pattern inspection method.

[Explanation of symbols]

1 substrate A few lights 4 half mirror 5 Infrared reflection mirror 6,13 cameras 7,7a A / D conversion circuit 8,8a binarization circuit 9 Inversion circuit 10 Reduction circuit 11,11a Smoothing circuit 12,14,16,17 memory 15,18 Synthesis circuit 19 Defect extraction circuit 20 Defect output circuit

Claims (2)

[Claims] 1. A fluorescent pattern image is obtained by detecting fluorescent reflected light generated from a substrate or a resist of a substrate having a wiring pattern, and the fluorescent pattern image is reduced and smoothed to obtain a pattern image of the substrate. A reflected light pattern image is obtained by detecting reflected light from the same place as the fluorescence detection pattern, and a pattern image obtained by smoothing this reflected light pattern image is subtracted from the fluorescence pattern image to extract defects on the wiring pattern. A wiring pattern inspection method characterized in that a defect pattern image is obtained. 2. The wiring pattern inspection method according to claim 1, wherein the defect pattern image in which the defect is extracted and the reflected light pattern image are combined to detect the defect pattern of the wiring pattern image.