JP3866966B2 - Method for measuring position of object having repetitive structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for measuring the position of an object having a repetitive structure using image retrieval, and more particularly to a method for measuring the position of an object having a repetitive structure suitable for use in a semiconductor inspection apparatus. The repetitive structure here is a structure in which terminals of the same shape, such as balls and pads, are arranged in a certain direction.
[0002]
[Prior art]
In order to measure the characteristics of a semiconductor mounted on a substrate such as a wafer level CSP (Chip Size Package) or a batch mold package, the electrodes must be in contact with the balls or pads which are terminals of each semiconductor element. For this purpose, the position of the semiconductor element must be accurately measured.
[0003]
FIG. 5 schematically shows a circuit composed of a plurality of semiconductor elements. FIG. 5A shows a work formed on a CSP or a mold package, and a plurality of devices 51 are arranged side by side.
[0004]
FIG. 5B is an enlarged view of one device, and a plurality of balls 511 as terminals are regularly formed on each device. An electrode is pressed against the ball to measure the characteristics of the device.
[0005]
In order to accurately press the electrode against the ball 511, the position of the ball 511, that is, the position of the device must be accurately known. Therefore, at the time of teaching, one device 51 or an array of characteristic balls 511 in the device 51 is registered as a reference image.
[0006]
The reference image is an image obtained by capturing a reference device. Further, in order to calculate the reference position of the device, the offset relationship between the reference image and the reference point on the device is registered at the same time during teaching.
[0007]
Next, the workpiece 5 to be measured is photographed, and it is searched whether there is a registered reference image in the photographed image. When an image that matches the reference image is found, the reference position of the device is calculated from the offset relationship between the registered reference image and the reference point on the device.
[0008]
If this operation is repeated for several devices on the workpiece 5 to be measured, for example, devices at four corners, the position of the workpiece can be calculated. This position measurement method uses a semiconductor wafer position measurement technique.
[0009]
[Problems to be solved by the invention]
However, such a method for measuring the position of a semiconductor device has the following problems.
[0010]
The workpiece 5 to be measured is a repetitive pattern having no features such as a ball 511 and a pad, and the manufacturing variation is large depending on the position of each device as compared with the semiconductor wafer. For this reason, there is a problem that the processing time increases because the measurement is repeated many times, and the position measurement fails in a severe case.
[0011]
Further, as described above, when the reference image is registered, the offset between the reference position of the reference image and the reference position of the device must be registered. Normally, the operator designates the position using a pointing device such as a mouse while looking at the image, so that it cannot be designated accurately. For this reason, there has been a problem that an error in position measurement increases.
[0012]
Therefore, the problem to be solved by the present invention is to provide a method for measuring the position of an object having a repetitive portion that can be reliably measured and has high measurement accuracy.
[0013]
[Means for Solving the Problems]
In order to solve such problems, the present invention provides:
In a method of measuring the position of an object having a repetitive structure using image retrieval,
The object having the repetitive structure is a semiconductor element, and the repetitive portion is a ball of the semiconductor element,
Generating an image of the ball from the design data, an image of the generated balls retrieves an image from the image of the ball side by side arranged the semiconductor element as a circular reference image, arranged on the basis of the position information of the found ball It is determined which of the semiconductor elements of the balls is arranged , and the found ball is arranged at a corresponding position in the semiconductor element based on the design data, and all balls of one semiconductor element are searched. Upon completion, the position information of the arrangement of the balls in the design data is compared with the position information of the balls obtained from the search results, and the position of the semiconductor element with respect to the position of the design data is determined. Even if there is a ball that could not be searched, the position of the semiconductor element can be determined.
[0014]
[0015]
[0016]
[0017]
[0018]
[0019]
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is a flowchart showing an embodiment of a semiconductor device position measuring method according to the present invention. It is assumed that the terminal shape of the device is a ball.
[0021]
In FIG. 1, first, the ball diameter and ball arrangement, which are the terminals of the device, are obtained from the design data. Next, the ball diameter is converted into the size of an image to be searched to create a device reference image.
[0022]
Next, a device for determining the position is determined. Since a large number of devices are arranged on the work, it is time consuming and inefficient to measure the positions of all devices by image search. For this reason, only a small number of devices at specific positions are measured, and the position of the workpiece is calculated from the measured values. The device for measuring this position is, for example, a device at the four corners of the workpiece.
[0023]
Subsequently, the workpiece image is searched by using the previously created reference image. Then, the correspondence between the found ball position and the ball position obtained from the design data is taken to determine the position of the device. Perform this operation for all devices whose positions are to be determined.
[0024]
When all of the determined device positions are determined, the correctness is judged from the mutual relationship of the position information, and the position of the workpiece is obtained by calculation. Since the positions of a plurality of devices are determined, the least square method or the like is used for the position of the work so that the error between the position of the device in the design data and the position of the device obtained by the image search is minimized.
[0025]
Next, a procedure for determining the position of the device from the position of the ball searched based on FIG. 2 will be described. FIG. 1A schematically shows an image of a workpiece. Reference numeral 1 is an image of a work, and 2 is an image of a device in the work 1.
[0026]
A black circle 21 represents a ball found as a result of searching the image 1 of the mold package using a circle which is a ball shape as a reference image. A white circle 22 represents a ball that is present but not found by image search.
[0027]
It is determined which device the ball is based on the position information of the searched ball, and the searched ball is arranged based on the design data. FIG. 5B is a diagram in which the balls are arranged in this way.
[0028]
When the search of all balls of one device is completed, the position information of the design data and the position information of the search result using the reference image are compared, and the error of the device is minimized by using the least square method or the like. Determine the position. Since there is a large number of balls in one device, the position of the device can be determined even if there is a ball 22 that could not be searched.
[0029]
After the positions of the devices at the four corners of the workpiece 3 are determined by the above method, the positions of the workpieces including these devices are determined by calculation. Since the positions of the devices at the four corners are accurately known, the positions of the workpieces can be accurately obtained.
[0030]
Depending on the mold package, one workpiece may be composed of a plurality of blocks. Each block includes a plurality of devices. A position measurement method in such a case will be described with reference to the flowchart of FIG.
[0031]
In FIG. 3, first, the positions of the devices at the four corners of the work are obtained to determine the positions of the work. Next, for each block included in the work, the positions of the four corner devices are obtained in order to determine the position of the block. The work and block positions are determined by the method shown in FIG.
[0032]
FIG. 4 specifically shows the position measuring method shown in the flowchart of FIG. In FIG. 4, reference numeral 3 denotes a work, and the work 3 includes three blocks 41, 42, and 43 in this order. Reference numerals 411 to 414, 421 to 424, and 431 to 434 respectively represent blocks 41, 42, and 43 and devices at the four corners of the work 3.
[0033]
First, the position of the work 3 is determined. For this purpose, the positions of the devices at the four corners of the work 3, that is, the devices 411, 412, 433, and 434 are measured, and the position of the work 3 is determined from the position information.
[0034]
Next, the position of each block is determined. First, the positions of the devices 411 to 414 are measured to determine the position of the block 41. Next, the positions of the devices 421 to 424 are measured to determine the position of the block 42. Then, the positions of the devices 431 to 434 are measured to determine the position of the block 43.
[0035]
By dividing the work into a plurality of blocks in this way, the position can be determined with high accuracy even for a complicated work including a large number of devices.
[0036]
In this embodiment, the terminal is described as a ball, but it may be a terminal of another shape such as a pad. In that case, the terminal may be searched using the shape of the terminal as a reference image. Further, the arrangement of the terminals can be applied not only to the grid arrangement shown in FIG. 2 but also to an arbitrary arrangement.
[0037]
In addition to measuring the position of semiconductor elements mounted on a circular substrate such as a batch mold package or a wafer-level CSP, it can also be applied to position measurements after separating semiconductor elements attached to a dicing ring. can do.
[0038]
Further, it can be applied to position measurement of not only semiconductor elements but also printed circuit boards having geometric features. Further, since the position can be measured for each terminal, the terminals can be inspected at the same time. For example, it may be determined that there is no terminal at a position where the terminal should be.
[0039]
In addition, since the work position is determined by measuring the positions of multiple terminals and devices, it is possible to correct work transfer deviations by incorporating a statistical method, which is optimal for operation. Can be achieved.
[0040]
【The invention's effect】
As is clear from the above description, the following effects can be expected according to the present invention.
In the present invention, an image of a ball is generated from design data, and the image of the ball is searched from images of semiconductor elements arranged side by side as the generated ball image as a circular reference image. Based on the position information of the found ball, it is determined which of the semiconductor elements the balls are arranged side by side. The found ball is arranged at a corresponding position in the semiconductor element based on the design data. When the search of all the balls of one semiconductor element is completed, the position information of the ball arrangement in the design data is compared with the position information of the ball obtained from the search result, and the position of the semiconductor element with respect to the position of the design data is determined. . By determining the position in this manner, the position of the semiconductor element can be determined even if there is a ball that could not be searched.
[0041]
[0042]
In addition, since the image search is performed using the image generated by geometric modeling from the design data instead of the actual image as the reference image, the influence of manufacturing variations at the time of the search is reduced compared to the method using the actual image as the reference image. There is an effect of not receiving directly.
[0043]
[0044]
[0045]
[0046]
[0047]
[0048]
[0049]
[0050]
[0051]
In the conventional method, since a real image is used as a reference image, it was not possible to detect even if the repeated portion was dropped. However, in the present invention, each of the repeated portions is searched, so even if one is dropped, it is detected. can do. Therefore, there is an effect that the measurement and the inspection of the repeated portion can be performed at the same time.
[Brief description of the drawings]
FIG. 1 is a flowchart showing an embodiment of the present invention.
FIG. 2 is a diagram for explaining an embodiment of the present invention.
FIG. 3 is a flowchart showing another embodiment of the present invention.
FIG. 4 is a diagram for explaining another embodiment of the present invention.
FIG. 5 is a diagram for explaining a conventional position measuring method;
[Explanation of symbols]
1, 3 Work 2, 411-414, 421-424, 431-434 Device 21, 22 Terminal 41, 42, 43 Block

Claims (1)

In a method of measuring the position of an object having a repetitive structure using image retrieval,
The object having the repetitive structure is a semiconductor element, and the repetitive portion is a ball of the semiconductor element,
Generating an image of the ball from the design data, an image of the generated balls retrieves an image from the image of the ball side by side arranged the semiconductor element as a circular reference image, arranged on the basis of the position information of the found ball It is determined which of the semiconductor elements of the balls is arranged , and the found ball is arranged at a corresponding position in the semiconductor element based on the design data, and all balls of one semiconductor element are searched. Upon completion, the object having a repetitive structure characterized in that the position information of the arrangement of the balls in the design data and the position information of the balls obtained from the search result are compared to determine the position of the semiconductor element with respect to the position of the design data Position measurement method.

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