JPH0521562A - Pattern matching method - Google Patents

Abstract

PURPOSE:To obtain a method capable of pattern matching while quickly obtaining the optimum TH value for each inspection object. CONSTITUTION:While a plurality of objects P1-Pn are observed in order with a camera 7 and the images are taken in, pattern matching of each image and a previously registered master image is performed in order by changing a TH value, the TH value excellent in matching ratio is extracted in order for each image, the TH value is registered in a computer, and mattern matching of post-inspection objects P1-Pn are performed, on the basis of the registered TH values.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern matching method, and more specifically, a pattern of an image of an object to be inspected and a master image captured by a camera while changing a TH value to obtain a TH value having a good matching rate. Matching is performed.

[0002]

2. Description of the Related Art For example, when wire bonding for connecting electrodes of a semiconductor chip and electrodes of a substrate with wires,
When forming bumps on a semiconductor chip, pattern matching is performed as a means for accurately obtaining the position of an electrode.

In pattern matching, an object such as an electrode is observed by a camera, an image of the object is captured, and the image is matched with a master image registered in advance in a computer to obtain the position of the object.

Since such pattern matching is performed by binarizing or multivalued processing of the image of the inspection object taken in by the camera, the threshold value (hereinafter referred to as TH value) must be determined. I have to.

Conventionally, in pattern matching, a master object is observed by a camera, the master image is displayed on a monitor TV, and an operator changes the TH value while watching the screen of the monitor TV.
The value is obtained and registered in advance in a computer, and the image of the inspection object and the master image are matched based on the registered TH value.

[0006]

That is, in the conventional means, the operator teaches the optimum TH value and performs the pattern matching based on this TH value. With such means, for example, the object to be inspected becomes dirty. If there is an optical change in the condition of the object due to
Since the binarized image and the multi-valued image also fluctuate, when the pattern matching is performed with the above-mentioned TH value, there is a problem that the matching rate is greatly reduced and a recognition error occurs. By the way, if a recognition error occurs in wire bonding, the operation of the device must be stopped, and the work efficiency cannot be improved.

Therefore, an object of the present invention is to provide means for performing good pattern matching while promptly obtaining an optimum TH value.

[0008]

To this end, according to the present invention, while a plurality of objects are sequentially observed by a camera and the images thereof are taken in, the TH value is changed and each image and a master image registered in advance are changed. Pattern matching is performed sequentially,
TH values with a good matching rate are sequentially extracted for each image, these TH values are registered in a computer, and pattern matching of an object for post-inspection is performed based on these registered TH values. It was done like this.

[0009]

According to the above construction, the optimum TH value can be quickly obtained for each inspection object, and good pattern matching can be performed.

[0010]

EXAMPLES Next, examples of the present invention will be described by taking the position recognition of electrodes in wire bonding as an example.

FIG. 1 is a perspective view of a wire bonding apparatus, in which 1 is a substrate, and semiconductor chips P (P1 to P
n) is installed. 2 is a drive unit, and a horn 3
Extends, and the capillary tool 4 is held at the tip thereof. An ultrafine wire 9 such as a gold wire is inserted through the capillary tool 4, and the electrode 5 of the chip P and the electrode 6 of the substrate 1 are connected by this wire 9. Reference numeral 7 is a camera for observing the electrodes 5 and 6, and 8 is a light source.

In carrying out pattern matching,
The operator selects the semiconductor chip PM to be the master. Then, the semiconductor chip PM is observed by the camera 7, the image is captured, displayed on a monitor television, the optimal TH value (TH0) is extracted while changing the TH value, and this TH0 is registered in a computer together with the master image. . FIG. 2 shows an image of the semiconductor chip PM captured by the camera 7. By setting the optimum TH0, as shown in the figure, the electrode 5 is bright and clearly observed in the black background.

Next, the first semiconductor chip P1 which is the inspection object is observed by the camera 7, the image thereof is captured, and pattern matching with the master image is performed. In this case, TH0 is adopted as the TH value, and pattern matching is performed based on this TH0.

Here, it suffices if a good matching rate can be obtained by TH0, but if the matching rate is low, the TH value is changed as shown in A of FIG. 3 to perform matching for this semiconductor chip P1. A highly efficient TH value (TH1) is extracted, pattern matching is performed based on this TH1, and this TH1 is registered in a computer.

Next, pattern matching of the second semiconductor chip P2 is performed. Also in this case, first, pattern matching is performed by TH0. Here, it is sufficient if a good matching rate can be obtained by TH0, but if the matching rate is low, the T registered in the computer will be used.
Pattern matching is performed by H1. And this TH
It is sufficient if a good matching rate is obtained by 1, but if the matching rate is low, the TH value is changed as shown in B of FIG. TH2) is extracted, pattern matching is performed based on this TH2, and this TH2 is registered in the computer.

Next, pattern matching of the third semiconductor chip P3 is performed. Also in this case, as in the case described above,
First, pattern matching is performed by TH0, TH1, and TH2 registered in the computer. If a good matching rate is not obtained in any case, the TH value is changed as shown in C of FIG. A TH value (TH3) with a high matching rate is extracted for P3, pattern matching is performed based on this TH3, and this TH3 is registered in the computer.

The above-described operation is repeated for the semiconductor chips P4, P5 ... Which are to be subjected to the post-inspection, and each optimum TH value is registered in the computer. As described above, the present method has the optimum TH value (TH1, TH2 ...
Since pattern matching is performed while obtaining (), it is possible to eliminate recognition errors and obtain good inspection results.

FIG. 4 shows the frequency of use of the TH value.
That is, a large number of semiconductor chips P1, P2, P3 ...
On the other hand, if pattern matching is performed many times by the above-described method, as shown in FIG. 4, the TH values (TH0, TH0,
A histogram of the usage frequency of TH1, TH2 ...) is obtained. In this embodiment, TH3, TH0, T
The frequency of use is high in the order of H5 ....

Therefore, while the pattern matching of the semiconductor chips is repeated a number of times, a histogram of such frequency of use is created, and by utilizing this result, the optimum TH value can be determined more quickly for each semiconductor chip. it can. That is, first, TH3 which is most frequently used
If the matching rate is low by this, pattern matching is sequentially performed by the next highest TH0, TH5. If the pattern matching is performed in the order of the TH values that are used most frequently, the probability that the optimum TH value can be extracted for the semiconductor chip in that short time becomes high, and the pattern matching can be speeded up.

[0020]

As described above, according to the present invention, while a plurality of objects are sequentially observed by the camera and the images thereof are taken in, the TH value is changed to perform pattern matching between each image and a master image registered in advance. Are sequentially performed, TH values with a good matching rate are sequentially extracted for each image, and these TH values are registered in a computer. Based on these registered TH values, the object of the post inspection is examined. Since I am trying to perform pattern matching,
It is possible to perform pattern matching at high speed while quickly setting the optimum TH value for each inspection object.

[Brief description of drawings]

FIG. 1 is a perspective view of a wire bonding apparatus according to the present invention.

FIG. 2 is a plan view of a semiconductor chip according to the present invention.

FIG. 3 is a TH value change diagram according to the present invention.

FIG. 4 is a frequency chart of TH values according to the present invention.

[Explanation of symbols]

P inspection object 7 camera

Claims (2)

[Claims] 1. A plurality of objects are sequentially observed by a camera, and while capturing the images, the TH value is changed and pattern matching is sequentially performed between each image and a master image registered in advance, and matching is performed for each image. While extracting TH values with a high efficiency one after another, registering these TH values in a computer, and performing pattern matching of the object of the post-inspection based on these registered TH values. Characteristic pattern matching method. 2. A plurality of objects are sequentially observed by a camera, and while capturing each image, the TH value is changed and pattern matching between each image and a master image registered in advance is sequentially performed. The TH values with a good matching rate are sequentially extracted, these TH values are registered in the computer, and the frequency of use of these TH values is calculated. A pattern matching method characterized by performing pattern matching of objects.