JP2002094230A - Apparatus for inspecting external shape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the inspection accuracy of a pattern formed on a substrate. SOLUTION: This apparatus for inspecting external shape is used to measure the shape of a pattern 3 formed on the surface of a substrate 1, compare/collate the shape and position of a measured pattern 20 with those of a specification pattern 21, and judge whether or not the formed pattern 3 is normal according to the obtained result. It is provided with distance measuring means 7 and 9 which measure a height data at every position of the surface of the substrate and store a measured data file 10, a basic judgment means 17 which binarizes the respective height data with an optimal initial threshold to obtain a measured data and compare/collate the measured pattern with the specification pattern to judge whether or not the measured pattern is normal, and a re-judgment means 18 which binarizes respective height data stored in the measured data file with a threshold obtained by a different method from the initial threshold if the measured pattern is not normal, obtains a measured pattern, and compares/collates the measured pattern with the specification pattern again to judge whether or not the measured pattern is normal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an outer shape inspection device for inspecting whether the shape and position of a pattern formed on a surface of a pattern with, for example, solder with concavities and convexities are in conformity with specifications.

[0002]

2. Description of the Related Art As shown in FIG. 5, a large number of patterns 3 are formed on a surface 2 of a printed wiring board 1 incorporated in various electronic devices. FIG. 6 shows a pattern 3 on this surface 2.
1 is a schematic cross-sectional view of a substrate 1 on which is formed. The resist 4 applied to the surface 2 of the substrate 1 is exposed and developed so as to correspond to each pattern 3 shown in FIG. 5, and a metal pad 5 is provided at a position where the resist 4 has been removed.
Solder 6 is provided on the top. Generally, the upper end position of the solder 6 is higher than the upper end position of the resist 4. A pattern in which the upper end surfaces of the solders 6 are joined together becomes each pattern 3 shown in FIG.

[0003] In recent years, as electronic devices have become smaller and lighter, substrates 1 incorporated in the electronic devices and electronic components mounted on the substrates 1 have also been reduced in size. Each pattern 3 is also small and fine. Therefore, it is necessary to strictly inspect that each pattern 3 is correctly formed on the surface 2 of the substrate 1 according to the specification.

More specifically, the pattern 3 on the entire surface 2 of the substrate 1 shown in FIG. 5 is read by an image reading device, and the read image data is binarized to obtain each pattern 3 on the surface 2 of the substrate 1. . It is necessary to inspect whether or not the measured position and shape of each pattern 3 match the position and shape of each pattern in the specification.

[0005] However, the brightness of the surface of the solder 6 and
Since the brightness of the surface of the resist 4 is similar, the pattern 3 on the entire surface 2 of the substrate 1 is read by a monochrome image reading device.
Is read, the read image of the pattern 3 cannot be binarized with high accuracy.

In order to eliminate such inconvenience, height data (distance data) of each position on the surface 2 of the substrate 1 from a predetermined reference position is measured by a distance sensor,
This height data is binarized by a threshold value d set between the upper surface position of the resist 4 and the upper surface position of the solder 6. The pattern of the height data binarized by the threshold value d is used as a measurement pattern on the surface 2 of the substrate 1. The position and the shape of the measurement pattern binarized by the threshold value d are checked to see if they match the position and the shape of each pattern in the specification.

[0007]

However, such a method of inspecting whether or not a pattern is formed on a substrate according to a specification using a distance sensor as described above also involves
There were still the following issues to be resolved.

FIG. 7 is a sectional view of the substrate 1, and FIG.
7A and 7B show a state in which the solder 6 is correctly arranged according to the specification, and FIGS. 7A and 7B show a state in which the solder 6 is not correctly arranged. FIG. 7 (a) shows the best condition. In FIG. 7 (a), fine burrs (projections) 4a are generated at the edges of the resist 4, but the solder 6 is correctly mounted. Here, FIG.
When the height data in the state of FIG. 7A and the height data in the state of FIG. 7A are binarized at the same threshold value d, the measurement pattern in FIG. 7B, the burrs (projections) 4a at the edge become an extra pattern, and the measurement pattern shown in FIG.

FIG. 7 (c) is defective because the solder 6 is mounted only about half of the metal pad 5, but when the threshold value d is erroneously set to the position of the metal pad 5, the measurement is failed. The pattern falls within the permissible range of the pattern in the specification and passes. Further, FIG. 7D is defective because the solder 6 is provided on the metal pad 5 too much, but when the threshold d is erroneously set at the tip of the solder 6, the measurement pattern becomes It passes within the permissible range of the specification pattern.

As described above, when the threshold value d is fixed to a constant value, there is a possibility that a pattern that should be passed may fail in some cases. Furthermore, if the setting of the threshold value d is significantly incorrect, there is a concern that a pattern that should be rejected will pass.

The present invention has been made in view of such circumstances, and when a determination result using an optimal initial threshold value is inappropriate, the threshold value is changed and the determination is performed again to thereby improve the substrate. It is an object of the present invention to provide a contour inspection apparatus capable of inspecting with high accuracy whether or not the shape and position of a pattern formed on the surface of a pattern match the shape and position of a specification pattern.

[0012]

SUMMARY OF THE INVENTION The present invention measures the shape of a pattern formed with irregularities on the surface of a substrate and compares the measured shape and position with the shape and position of a specification pattern. The present invention is applied to a contour inspection apparatus that determines whether a pattern formed by matching is acceptable or not.

[0013] In order to solve the above-mentioned problems, in the contour inspection apparatus of the present invention, a distance measuring means for measuring height data at each position on the surface of the substrate and storing the same in a measurement data file; Basic determination means for binarizing each of the height data stored in the memory with an optimal initial threshold value to obtain a measurement pattern, and comparing the measured pattern with a specification pattern to determine whether the measurement pattern is acceptable or not; If the measurement pattern is determined to be unacceptable, the height data stored in the measurement data file is binarized with a threshold obtained by a method different from the initial threshold to obtain a measurement pattern, and the measurement pattern and the specification pattern are obtained. Re-determining means for comparing and collating with and determining whether the measurement pattern is acceptable or not.

According to another aspect of the present invention, in the contour inspection apparatus of the invention described above, the method of obtaining the threshold is sequentially changed until the measured pattern is determined to be acceptable, and the redetermining means is performed a predetermined number of times.

In the contour inspection apparatus thus constructed, height data at each position on the surface of the substrate is measured by the distance measuring means and written into the measurement data file. Then, first, each height data stored in the measurement data file is binarized into a measurement pattern with an optimal initial threshold value obtained by, for example, a statistical method or a theoretical method, and this measurement pattern is compared with a specification pattern. Is done. Then, when the comparison result is rejected, each height data is binarized using a threshold value obtained by a method different from the initial threshold value, and compared with the specification pattern.

Further, when rejection occurs in this determination, each height data is binarized using a threshold value obtained by another method, and is compared with a specification pattern.

A pattern formed on the substrate can be regarded as a pass if the measured pattern binarized by the threshold value obtained by any of the methods matches the specification pattern. Of course, the threshold value obtained by each method cannot be a clearly wrong value, so if the formed pattern is out of the allowable range, even if the method of obtaining the threshold value is changed,
Until the end, tolerances such as volume, height, area, etc., cannot be satisfied at the same time, so it does not pass.

Still another aspect of the present invention is the contour inspection apparatus according to the above-mentioned invention, wherein the threshold used in the re-determination means executed first is set at a position separated by a predetermined distance outside a circumscribed rectangle in contact with the specification pattern. It is calculated using height data at positions corresponding to a plurality of surrounding points and maximum height data among height data at positions corresponding to diagonal positions of the circumscribed rectangle.

In such a threshold value calculating method, the height data at the position where the pattern is formed in the height data at each position on the surface of the substrate and the height data at the position where no pattern is formed are included. And can be easily detected,
For example, these intermediate values can be used as a new threshold.

Further, with respect to the result obtained by this method, the surrounding points are compared with the average height of the surroundings to determine whether or not the points can be recognized as solder, and more detailed data can be obtained.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating a schematic configuration of the external shape inspection apparatus according to the embodiment. As described with reference to FIGS. 5 and 6, a large number of patterns 3 are formed on the surface 2 of the substrate 1 by the solder 6 as described with reference to FIGS. 5 and 6.

In FIG. 1, a distance sensor 7 is two-dimensionally scanned by a scanning mechanism 8 at a position above the substrate 1 in a plane parallel to the surface 2 of the substrate 1. In the course of scanning, the distance sensor 7 measures the distance to the substrate 1 for each position on the front surface 2 and sends it to the height data changing / writing unit 9. As the distance sensor 7, for example, an optical distance meter using a laser beam is employed.

The height data conversion / write unit 9 includes a distance sensor 7
Is converted into height data in which the substantially middle position in the thickness direction of the substrate 1 is set to “0 (reference position)” and the resist 4 and the solder 6 are set to the (+) direction. Write to the measurement data file 10. Therefore, the measurement data file 10 stores height data at two-dimensional coordinate positions on the surface 2 of the substrate 1.

The specification data memory 11 stores specification data of each pattern 3 formed with irregularities on the surface of the substrate 1 to be measured. More specifically, an overall view memory that stores an overall view of the surface of the substrate 1, a pattern memory 12 that stores each pattern, that is, the shape and area of each specification pattern, and a position on the substrate 1, A circumscribed rectangular memory 13 for storing a rectangular shape and a position on the substrate 1 is formed. The circumscribed rectangle is a rectangle in which at least four sides are in contact with the outer side of the target pattern. Therefore, when the pattern is a square, circle, or equilateral triangle, the circumscribed rectangle is a square.

The allowable range memory 14 stores an allowable range when the binarized measurement pattern is compared with a corresponding specification pattern stored in the specification data memory 11. More specifically, the area of the measurement pattern is stored in% (percent) with respect to the area of the specification pattern.

When the pattern 3 is correctly formed on the substrate 1 by the solder 6, a strict allowable range (standard)
Is acceptable, but loose strict tolerance (standard)
In, when the pattern 3 is not correctly formed, there is a concern that a pass determination may be erroneously made. Therefore, a strict allowable range is set in the allowable range memory 14.

An output unit 15 for displaying and printing out the final inspection result (pass / fail judgment result) and a storage unit 16 for storing the final inspection result (pass / fail judgment result) are provided.

Further, in this external shape inspection apparatus, a four-stage determination unit including a basic determination unit 17, a re-determination unit 18, a re-redetermination unit 19, and a re-re-determination unit (not shown) formed as a program module on the application program is provided. Is provided.

Next, specific operations of the basic determination unit 17, the re-determination unit 18, the re-redetermination unit 19, and the basic determination, re-determination, re-redetermination, and re-re-determination in the re-re-determination unit will be sequentially described. (A) Basic Determination The basic determination unit 17 binarizes each height data at each coordinate position of the substrate 1 to be measured stored in the measurement data file 10 with an optimal initial threshold value d ₀ , and , And each measurement data corresponding to each pattern 3 formed on the substrate 1 is obtained from the binary data of the entire substrate 1. Then, the obtained measurement patterns are compared with the corresponding specification patterns stored in the specification data memory 11 and collated to determine whether each measurement pattern is acceptable or not.

Next, the detailed operation of the basic determination unit 17 will be described. The basic determination unit 17 includes an initial threshold calculation unit 17
a, a primary binarization processing unit 17b, a pattern detection unit 17c,
It comprises a pattern comparing section 17d and a pass / fail determination section 17d.

The initial threshold value calculation unit 17a stores a histogram (height distribution characteristic) for each data value (height value) in height data at all coordinate positions of the substrate 1 to be measured stored in the measurement data file 10. Figure)
A set of data values (height values) in which a pattern exists (the solder 6 exists) and a set of data values (height values) in which the pattern does not exist (the solder 6 does not exist) are obtained. data values (height values) the optimum initial threshold d _0.

The primary binarization processing section 17b calculates each height data at each coordinate position of the substrate 1 to be measured stored in the measurement data file 10 with the previously obtained initial threshold value d ₀ [1] or It is binarized to “0” to obtain binarized data of the entire substrate 1. The pattern detection unit 17c outputs the binarized data of the entire substrate 1.
From the quantified data, a plurality of measurement patterns are obtained by collecting the height data of [1].

The pattern comparing section 17d searches the pattern memory 12 of the specification data memory 11 with the obtained position coordinates of each measurement pattern, detects a corresponding specification pattern, and detects both the measurement pattern and the specification pattern. Is compared. The pass / fail determination unit 17e performs pass / fail determination on each measurement pattern based on the result of comparison and comparison with the specification pattern.

In general, the quality (pass / fail) of each solder 6 formed on the substrate 1 is compared with the specification by comparing the degree of coincidence of the position, area, volume, circumscribed rectangle width, height, etc., and the height. There are non-uniformities, bridges (adjacent patterns are in contact with each other), and the like. The pass / fail determination unit 17e of the basic determination unit 17 determines pass / fail by comparing each binarized two-dimensional measurement pattern with a corresponding two-dimensional specification pattern. , Position, area, and bridge.

More specifically, the position and the area are compared with the position and the area of the specification pattern, and it is determined whether or not the error falls within the allowable range stored in the allowable range memory 14. If any one of them falls outside the allowable range, the corresponding measurement pattern is rejected. If a bridge exists, the corresponding measurement pattern is rejected. Others will be accepted.

FIGS. 2A, 2B and 2C are diagrams showing the area and positional relationship between the binarized measurement pattern 20 indicated by a solid line and the specification pattern 21 indicated by a dotted line. FIG.
2A shows a pass state, and FIGS. 2B and 2C show a reject state. Further, the rejected state is shown in FIG.
The state is classified into two types, an "overlapping state" shown in FIG. 2B and a "non-overlapping state" shown in FIG. 2C.

The basic determination unit 17 transmits only the rejected measurement pattern 20 to the next re-determination unit 18 with information specifying the relevant measurement pattern 20, and changes the threshold d. Instruct redetermination.

(B) Redetermination If the measurement pattern 20 determined to be unacceptable by the basic determination unit 17 exists, the redetermination unit 18 compares the height data stored in the measurement data file 10 with the initial threshold value. The measurement pattern 20 is obtained by binarization using the secondary threshold value d ₁ obtained by a method different from d _0, and the measurement pattern 20 that has been determined to be rejected by the basic determination unit 17 earlier in the measurement pattern 20 and the specification The measurement pattern 2 is compared with the corresponding specification pattern 21 stored in the pattern memory 12 of the data memory 11 and compared.
The pass / fail of 0 is determined again.

Next, the detailed operation of the redetermining section 18 will be described. The re-determination unit 18 includes a pattern circumscribed rectangle calculation unit 18a, a circumscribed rectangle overlap determination unit 18b, a secondary threshold calculation unit 18c, a secondary binarization processing unit 18d, and a pass / fail determination unit 18e.
It is composed of

In the re-determining section 18, each of the measurement patterns 20 determined to be rejected input from the basic determining section 17 is referred to as an "overlapping state" shown in FIG.
And the determination process is performed again.

(B-1) In the case of non-overlapping state The re-determination processing when the rejected measurement pattern 20 in the non-overlapping state shown in FIG. 2C occurs will be described with reference to FIG. First, the pattern circumscribed rectangle calculation unit 18a is activated, and calculates the circumscribed rectangle 22 of the rejected measurement pattern 20. As described above, the circumscribed rectangle 22 is a rectangle whose four sides are in contact with the outer edge of the rejected measurement pattern 20.

Next, four points separated by a predetermined distance on the extension of the two diagonal lines 24a and 24b of the obtained circumscribed rectangle 22 are defined as peripheral points 22a, 22b, 22c and 22d. And these four peripheral points 22a, 22b, 22
c, measured height data A ₁ , A ₂ , 22 d at 22 d,
A ₃ and A ₄ are read from the measurement data file 10 and the highest height data Ah among the _four height data A ₁ , A ₂ , A ₃ and A ₄ is specified. Next, height data Bm of the highest position 25 among the positions on the two diagonal lines 24a and 24b in the circumscribed rectangle 22 is obtained.

The height data Ah and Bm are both the solder 6
(Ah <Hs, B
m <Hs) is binarized each height data with abnormally high threshold, it is determined that the pattern 3 should be originally was not detected, it is determined that the binarization errors due to initial threshold d _0. In this case, the process returns to the primary binarization processing unit 17b in the basic determination unit 17, and the relevant measurement pattern 2 determined to be rejected.
The binarization process is performed again on the height data of the predetermined area including 0.

The maximum height data Ah of the surrounding points 22a to 22d is less than the specified height Hs, and only the height data Bm at the highest position 25 on the diagonal lines 24a and 24b in the circumscribed rectangle 22 is the specified height Hs. In the above case (Ah <Hs, Bm
.Gtoreq.Hs), the rejected measurement pattern 20 is determined to be noise solder other than the pattern 3 of the normal solder 6. In this case, the error solder is determined without performing the measurement again.

(B-2) In the case of the overlapping state The measurement pattern 2 of the rejection in the overlapping state shown in FIG.
The redetermination process when 0 occurs will be described with reference to FIG.

First, the pattern circumscribing rectangle calculating section 18a is activated, and the circumscribing rectangle 23 of the specification pattern 21 overlapping the rejected measurement pattern 20 is obtained. Specifically, the corresponding circumscribed rectangle 23 is read from the circumscribed rectangle memory 13 of the specification data memory 11. And this specification pattern 2
Four peripheral points 23a, 23b separated by a predetermined distance on an extension of two diagonal lines 26a, 26b of one circumscribed rectangle 23;
23c and 23d are obtained, and the four surrounding points 23a and 23d are determined.
b, 23c, and 23d, height data A ₁ , A ₂ , A
_3, reads the A ₄ from the measurement data file 10..

The four height data A ₁ , A ₂ , A ₃ , A ₄
Among the height data located on the extension of the same diagonal line 26a, 26b, the lower one is selected. Among the two lower height data, the higher one height data Aj is detected. In this method, 4
It does not matter if one of the peripheral points 23a, 23b, 23c, 23d is located on the solder 6.

That is, as shown in FIG. 4, when the measurement pattern 20 of the pattern 3 of the solder 6 is shifted from the specification pattern 21, for example, four peripheral points 23a, 23b, 2
The height data Aj of the highest peripheral point among the peripheral points where it is considered that the pattern 3 of the solder 6 does not exist among 3c and 23d is extracted.

Next, the secondary threshold value calculating section 18c is activated,
The height data B at the highest position 27 is extracted from the height data at each position on the two diagonal lines 26a and 26b of the circumscribed rectangle 23 of the specification pattern 21. And
It is confirmed that the difference between the heights (B-Aj) is equal to or greater than a specified value Hd determined by the thickness of the solder 6. Then, the secondary threshold d _{1 is obtained} by the following equation.

D ₁ = (B-Aj) / 2 If the difference between the heights (B-Aj) is less than a prescribed value Hd determined by the thickness of the solder 6, the two diagonal lines 26
Since it can be considered that the pattern 3 of the solder 6 does not exist on the a and 26b, the height data Bm at the highest position 27a in the circumscribed rectangle 23 of the specification pattern 21 is measured data memory 1
Extract from 0. Then, the secondary threshold d _{1 is obtained} by the following equation.

D ₁ = (Bm−Aj) / 2 In this manner, the height data A ₁ , A ₂ , A of the four surrounding points 22 a, 22 b, 22 c, 22 d in the circumscribed rectangle 23 of the specification pattern 21. _3, a ₄ and diagonal 36a, 26
Since the secondary threshold value d ₁ is calculated with each of the height data b, the height data B (Bm) at the position where the pattern 3 of the solder 6 exists does not exist with a small number of samples of the height data. securely grasp the height data a position, a short time can be efficiently calculate an optimum secondary threshold d ₁ corresponding to the failure of the measurement pattern 20.

Next, the secondary binarization processing section 18d is activated, and among the respective height data of the entire board 1 stored in the measurement data file 10, the basic determination section 17 first fails. for each predetermined region including the respective measurement patterns 20, binarizes the secondary threshold value d ₁ which is set in the measurement pattern 20. 2 for each predetermined area including each measurement pattern 20
The measurement pattern 20 is obtained again from the binarized data.

In this case, the secondary threshold value d ₁ is equal to the initial threshold value d _0.
The secondary threshold value d ₁ is different from the initial threshold value d ₀ . Therefore, the measurement pattern 20 obtained by binarization at the secondary threshold d ₁ is the measurement pattern 2 obtained by binarization at the initial threshold d _0.
It does not always match 0.

Then, the synthetic fertilizer judging section 18 e is activated, and the measurement pattern 20 which has failed first is compared with the corresponding specification pattern 21 stored in the pattern memory 12 of the specification data memory 11, thereby re-checking. Make a pass / fail decision.

More specifically, the area of the measurement pattern 20 which failed the previous time, the area of the circumscribed rectangle 22 of the measurement pattern 29, and the corresponding specification pattern 21 stored in the pattern memory 12 of the specification data memory 11. Is compared with the area of the corresponding circumscribed rectangle 23 stored in the circumscribed rectangle memory 13 to determine whether or not it falls within the allowable range stored in the allowable range memory 14.

The reason for comparing the area of the circumscribed rectangle 22 of the measurement pattern 20 with the area of the circumscribed rectangle 23 of the specification pattern 21 in addition to the area of the measurement pattern 20 is as follows.
This is because there is a concern that the deformed measurement pattern 20 may be erroneously determined to pass if only the area of the measurement pattern 20 is used.

Then, the measurement pattern 20 which was within the allowable range and failed the previous time is newly accepted. Only the measurement pattern 20 rejected by the pass / fail judgment unit 18e is transmitted to the next re-judgment unit 19 with the information for identifying the relevant measurement pattern 20 added, and the threshold d is changed again and re-executed. Instruct the judgment.

(C) Re-judgment When the re-judgment unit 18 determines that there is a measurement pattern 20 that has been rejected, the re-judgment unit 19 compares the height data stored in the measurement data file 10 with the initial threshold d _0. and obtaining a measurement pattern 20 is binarized by a cubic threshold d ₂ obtained in the secondary threshold value d ₁ and different approach, the measurement pattern 20 by the re-determination unit 18 is determined to fail in the measurement pattern 20 Is compared with the corresponding specification pattern 21 stored in the pattern memory 12 of the specification data memory 11, and the pass / fail of the measurement pattern 20 determined to be rejected is determined again.

Next, the detailed operation of the re-determining section 19 will be described. This re-redetermination unit 19 includes the pattern area determination unit 1
9a, tertiary threshold calculator 19b, tertiary binarization processor 19
c, a pass / fail determination unit 19d.

First, the pattern area determination section 19a is activated, and the area of the measurement pattern 20 rejected by the pass / fail determination section 18c of the re-determination section 18 is measured. Then, the tertiary threshold value calculation unit 19b is activated and the measured measurement pattern 20 is measured.
The measurement pattern 20 rejected according to the value of the area of
The tertiary threshold value d ₂ for each is determined.

(A) If the measured area exceeds the maximum reference value indicated by the percentage of the area of the specification pattern 21 set in advance, the threshold value d is increased.

Tertiary threshold d ₂ = (Maximum height Bm in measurement pattern 20) − (Acceptable minimum height of specification pattern 21) (b) Measured area is less than the maximum reference value and allowable range memory If it exceeds the upper limit of the allowable range stored in 14, the threshold d is increased.

Third-order threshold d ₂ = [(highest height Bm) -second-order threshold d ₁ ] / 2 + second-order threshold d ₁ = [(highest height Bm) + second-order threshold d ₁ ] / 2 (c) Measurement If the area is less than the lower limit of the allowable range,
Lower the threshold value d.

The tertiary threshold d ₂ = [(maximum height Bm) − (surrounding height Ah)] / 3+ (surrounding height Ah) = [(maximum height Bm) +2 (surrounding height Ah)] / 3. In this way, the value of the tertiary threshold value d ₂ for binarizing the height data is re-determined according to the size of the area of the measured measurement pattern 20. Set a value that is most easily passed for judgment.

When the calculation processing of the optimum tertiary threshold value d ₂ for each rejected measurement pattern 20 is completed, the tertiary binarization processing unit 19c is activated and the substrate stored in the measurement data file 10 Each of the height data of the whole 1 is binarized with each of the previously calculated tertiary thresholds d ₂ .

Specifically, of the height data of the entire board 1 stored in the measurement data file 10, for each predetermined area including each measurement pattern 20 that has been rejected by the re-determining section 18, Binarization processing is performed using the tertiary threshold value d ₂ set for the measurement pattern 20. The measurement pattern 20 is obtained again from the binarized data binarized for each predetermined area including each measurement pattern 20.

In this case, since each tertiary threshold value d ₂ is calculated by a method different from the initial threshold value d ₀ and the secondary threshold value d ₁ ,
Each cubic threshold d ₂ are different values as the secondary threshold value d ₁ and the initial threshold value d _0. Therefore, the measurement pattern 20 obtained by binarization at each of the tertiary thresholds d ₂ is the measurement pattern 2 obtained by binarization at the previous secondary threshold d ₁ and the initial threshold d _0.
It does not always match 0.

Then, the pass / fail judgment unit 19d is activated, and the measurement pattern 20 rejected by the re-judgment unit 18 is compared with the corresponding specification pattern 21 stored in the pattern memory 12 of the specification data memory 11. By
The pass / fail judgment is performed again.

More specifically, the pass / fail judgment unit 1 of the re-judgment unit 18
8e, the area of the measurement pattern 20 that failed the previous time, the area of the circumscribed rectangle 22 of the measurement pattern 20, the area of the corresponding specification pattern 21 stored in the pattern memory 12 of the specification data memory 11, and the like. By comparing and referring to the area of the corresponding circumscribed rectangle 23 stored in the circumscribed rectangle memory 13, it is determined whether or not the area falls within the allowable range stored in the allowable range memory 14.

When the entire area of the substrate 1 is large and the distance data is read a plurality of times by the distance sensor 7, if the pattern 3 is located at the boundary, one pattern 3
Is divided and detected as two measurement data 20.
In such a case, since the area of each of the divided measurement data 20 does not match the area of the specification pattern 21, the pass / fail determination is not performed on each of the divided measurement data 20.

Then, the previously failed measurement pattern 20 falling within the allowable range is newly accepted. Only the measurement pattern 20 rejected by the fertilizer determination unit 19d is transmitted to a re-re-determination unit not shown in FIG.
Is changed again, and the determination is again made.

(D) Re-re-judgment The re-re-judgment unit has almost the same configuration as the re-re-judgment unit 19, and if there is a measurement pattern 20 judged to be rejected by the re-re-judgment unit 19, the Each stored height data is binarized by a method different from the initial threshold value d ₀ , the secondary threshold value d ₁ , and the tertiary threshold value d ₂ , using the quaternary threshold values d ₃ obtained for each rejected measurement data 20. Measurement pattern 20 is obtained. Then, the measurement pattern 20 determined to be rejected by the re-re-re-determination unit 19 is compared with the corresponding specification pattern 21 stored in the pattern memory 12 of the specification data memory 11, and the measurement pattern determined to be rejected is compared. The pass / fail judgment for 20 is performed again.

The method of calculating each quaternary threshold value d ₃ in this case is performed in accordance with the method of calculating each tertiary threshold value d ₂ in the re-determination section 19 again.

Then, the basic judgment unit 17, the re-judgment unit 18,
The re-determination section 19 and the re-re-determination section 19 output each of the patterns 3 formed on the substrate 1 that finally passed and the unrejected patterns 3 that did not pass until the end.
Is displayed or output as a result of the pass / fail determination. Further, these determination results are stored and held in the storage unit 16.

In the contour inspection apparatus thus configured, for example, in order to measure the shape of each pattern 3 formed with irregularities on the substrate 1, each position 3 is measured using the distance sensor 7. It is obtained as height data, the height data is binarized with a threshold value appropriately set, and from this binarized data,
The measurement data 20 corresponding to the actual pattern 3 is obtained. By comparing each measurement pattern 20 thus obtained with the specification pattern 21 of each pattern 3, it is determined whether each measurement pattern 20, that is, each pattern 3 is correctly formed on the substrate 1. Has been determined.

In this case, when the quality of the pattern 3 formed with irregularities such as the solder 6 is determined, the measurement pattern 2
The most important issue is how to appropriately set the threshold value d used to obtain 0. When the measurement pattern 20 is obtained using the inappropriate threshold value d, the pattern 3 that should be passed is rejected.

Therefore, in the external shape inspection apparatus according to the embodiment, the measurement pattern 20 (pattern 3) which failed at the optimum initial threshold value d ₀ is compared with the corresponding measurement pattern 2 (pattern 3).
Until 0 (pattern 3) is determined to be acceptable, the threshold d is sequentially changed and the measurement pattern 20 is determined again.

Specifically, in the basic determination unit 17,
The height data of the entire surface 2 of the substrate 1 is binarized with one optimal initial threshold value d ₀ statistically or theoretically obtained to obtain a measurement pattern 20. That is, in the basic determination unit 17, it is carried out quality determination by measurement pattern 20 which is binarized by a single initial threshold d ₀ being optimal estimation.

[0079] Then, with respect to the basic determination unit 17 the measurement pattern 20 was rejected in the (pattern 3), by setting the individual secondary threshold d ₁ in the redetermination section 18, the measurement pattern 20 ( The pass / fail judgment is performed again for each pattern 3).

Similarly, in the re-re-determination section 19 and the re-re-re-determination section, each measurement pattern
A third threshold d2 and a fourth threshold d are individually set for (pattern 3), and each measurement pattern 20 (pattern 3) is set.
The pass / fail judgment is performed again every time.

As described above, for each pattern 3 (measurement pattern 20) formed on the surface 2 of the substrate 1 with irregularities,
The binarization is performed with the threshold value d most suitable for the corresponding pattern 3 (measurement pattern 20), and the pass / fail judgment is performed. Therefore, the occurrence rate of a situation in which the pattern 3 that should originally pass is erroneously rejected is reduced, and the accuracy of the pass / fail determination of each pattern 3 formed on the substrate 1 can be greatly improved.

The present invention is not limited to the above embodiment. In the apparatus of the embodiment, when the basic determination unit 17 determines rejection, the threshold value d is changed and re-determination is performed up to three times. However, the number of re-determinations performed with the threshold d changed is not limited to three, but can be set to any number as needed.

[0083]

As described above, in the contour inspection apparatus of the present invention, the height data of a pattern formed with irregularities on a substrate is read, and a pass / fail test is performed by using a threshold value and a binarized measurement pattern. In the case where the judgment is made, if the judgment result using the initial threshold value considered to be optimal is rejected, the threshold value is changed and the judgment is performed again.

Therefore, the pattern formed on the substrate is consequently determined to be acceptable or unacceptable using the optimum threshold value for the pattern, and the shape and position of the pattern formed on the surface of the substrate are determined by the shape and position of the specification pattern. Can be inspected with high accuracy.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a contour inspection apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a determination result in the outer shape inspection device of the embodiment.

FIG. 3 is an exemplary view for explaining a determination method in the external shape inspection apparatus according to the embodiment;

FIG. 4 is a view for explaining a calculation method of a threshold value in the contour inspection apparatus of the embodiment.

FIG. 5 is a view showing a pattern formed on a substrate;

FIG. 6 is a diagram showing a cross-sectional shape of a substrate.

FIG. 7 is a diagram showing a relationship between pass / fail judgment of solder on a substrate and a threshold value;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Surface 3 ... Pattern 4 ... Resist 6 ... Solder 7 ... Distance sensor 8 ... Scanning mechanism 9 ... Height data conversion writing part 10 ... Measurement data file 11 ... Specification data memory 14 ... Allowable range memory 17 ... Basic Judgment unit 18 Re-judgment unit 19 Re-judgment unit

Continued on the front page F term (reference) 2F065 AA03 AA54 AA58 AA59 CC26 FF09 FF11 FF61 JJ16 MM07 PP22 QQ08 QQ23 QQ25 QQ41 QQ43 TT03 2F069 AA66 BB14 GG07 GG39 GG72 GG77 HH09 JJ07 AC01 BB00

Claims (3)

[Claims] 1. The shape of a pattern (3) formed with irregularities on the surface of a substrate (1) is measured, and the shape and position of the measured pattern (20) and the shape and position of a specification pattern (21) are measured. In a contour inspection apparatus which determines pass / fail of the formed pattern (3) by comparing and checking the position, height data at each position on the surface of the substrate is measured and stored in a measurement data file (10). A distance measuring means (7, 8, 9); binarizing each height data stored in the measurement data file with an optimal initial threshold value to obtain a measurement pattern; comparing the measurement pattern with the specification pattern; Basic determination means (17) for determining whether or not the measurement pattern is acceptable. If the measurement pattern is determined to be rejected by the basic determination means, each height data stored in the measurement data file is determined. Re-determining means (18) for binarizing the data with a threshold value obtained by a method different from the initial threshold value to obtain a measurement pattern, comparing the measurement pattern with the specification pattern and determining whether the measurement pattern is acceptable or not. External inspection equipment provided. 2. The external shape inspection apparatus according to claim 1, wherein the method for obtaining the threshold is sequentially changed until the measurement pattern is determined to be acceptable, and the re-determination unit is performed a predetermined number of times. 3. The threshold value used in the re-determining means executed first corresponds to a plurality of peripheral points set at positions separated by a predetermined distance outside a circumscribed rectangle (23) contacting the specification pattern (21). 3. The height data is calculated using height data of a position to be set and maximum height data among height data of positions corresponding to diagonal positions of the circumscribed rectangle. Outline inspection equipment.