JP2001135695A - Method for measuring registration precision and mark to be used by the same method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure the registration precision of a resist pattern to a reference layer (a resist pattern formed through a thin film on the reference layer) with high precision. SOLUTION: A registration precision measurement mark is constituted of a reference mark 10 and an overlap mark 20. Dummy patterns (patterns which are not used for measurement) 3 and 4 are formed inside and outside the reference pattern 11 as the reference mark 10. Then, the projecting part of a thin film formed at the upper part of the reference pattern 11 is considered as a reference pattern, and intervals x1 and x2 between the outside line of the reference pattern 11 and the inside line of a registration pattern 21 corresponding to this are measured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for measuring the overlay accuracy of a resist pattern on a reference layer (a resist pattern formed on a reference layer via a thin film),
And the marks used in this method.

[0002]

2. Description of the Related Art In a wafer process for manufacturing a semiconductor device, it is important to form a fine pattern accurately and to overlay upper and lower patterns with high accuracy. For this purpose, the overlay accuracy of a pattern already formed on the lower layer (lower pattern) and a pattern to be formed thereon (upper pattern) is measured. As a conventional example of such an overlay accuracy measuring method, the following method is exemplified.

First, a mark (reference mark) for measuring overlay accuracy is formed on the lower layer (reference layer) simultaneously with the patterning of the lower pattern. Next, a thin film for an upper pattern is formed on the lower layer, and a resist pattern is formed on the thin film. When forming a resist pattern, a mark (alignment mark) for measuring overlay accuracy is formed as a part of the resist pattern. FIG. 6 is a plan view showing an example of a combination of the reference mark and the alignment mark.

The reference mark 10 is composed of one reference pattern 11. The reference pattern 11 is a square frame having a predetermined width. This alignment mark 20 is composed of one alignment pattern 21. This matching pattern 21
Is a square frame shape larger than the reference pattern 11 and has the same width as the reference pattern 11. Then, x
With respect to the direction and the y direction, the reference pattern 11 is defined on one side and the other side with respect to the center of the reference pattern 11.
And the distances x ₁ , x ₂ , y ₁ , and y ₂ between the outer line of and the corresponding inner line of the matching pattern 21 are measured.
Here, since the reference pattern 11 exists below the thin film, in practice, the convex portion (Ht in FIG. 5) formed on the reference pattern 11 of the thin film is regarded as the reference pattern, and this measurement is performed. It is carried out. Then, the difference (x ₁ −x ₂ ), (y ₁ −y ₂ ) between these measured values is calculated as the amount of deviation in each direction.

Japanese Patent Laid-Open Publication No. Hei 10-125751 discloses an example in which a reference mark 10 is composed of two reference patterns 11 and 12 and an alignment pattern 21 is arranged between the two reference patterns as shown in FIG. I have. In this case, for each of the values x ₁ , x ₂ , y ₁ , and y ₂ , values for the two reference patterns 11 and 12 (for example, for x ₁ , the outer line of the reference pattern 11 and the corresponding matching pattern) Both the distance x ₁₁ between the inner line of the reference pattern 12 and the distance x ₁₂ between the inner line of the reference pattern 12 and the corresponding outer line of the matching pattern 21) are measured, and the average value thereof is calculated as each value x ₁ , X ₂ , y ₁ , y ₂ .

[0006]

However, such prior art has room for improvement in the measurement accuracy of the overlay accuracy. An object of the present invention is to make it possible to measure the overlay accuracy of a resist pattern (a resist pattern formed on a reference layer via a thin film) on a reference layer with high accuracy.

[0007]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, obtained the following findings and completed the present invention. The thin film formed on the reference layer is
Depending on the pattern formation density of the reference layer, a difference occurs in the cross-sectional shape of a portion (sidewall portion) formed on the sidewall of the pattern.
That is, as shown in FIG. 5 (a cross-sectional view taken along the line BB in FIG. 6), since the pattern formation density is high inside the reference pattern 11 (11a, 11b), the side wall Hu of the thin film H has a gentle inclination. It has become. On the other hand, since the pattern formation density is low outside the reference pattern 11, the side wall portions H1 and H2 of the thin film H in this portion have a steep slope.

[0008] The pattern formation density of the reference layer S at the outer reference pattern 11, since in the x ₁ side and x ₂ side not always the same, x ₁ side of the reference pattern 11
In the side wall portion H2 of the thin film of the reference pattern 11b of the side wall portions H1 and x ₂ side of a thin film of a, there is a difference in the degree of tilt. Here, the measurement of x ₁ and x ₂ is based on the reference pattern 1 of the thin film H.
Because have gone considers protrusions Ht formed on one of the upper and the reference pattern, if the degree of inclination of the side wall portions H1, H2 of the thin film varies, a difference in the measurement accuracy between x ₁ and x ₂ may occur.
As a result, the measurement accuracy of the overlay accuracy decreases.

Accordingly, the pattern formation density of the reference layer S at the outer reference pattern 11 is set to be always the same in the x ₁ side and x ₂ side, the side wall portions H1, H2 of the thin film H
If the degree of tilt in the same, becomes the measurement accuracy in the x ₁ and x ₂ same, the higher the overlay accuracy measurement accuracy. Based on the above findings, the present invention forms a reference mark having a pattern (reference pattern) having a predetermined width and a predetermined shape on a reference layer, and a part of a resist pattern formed on the reference layer via a thin film. An alignment mark having a predetermined width and a predetermined shape pattern (alignment pattern) is formed, and the convex portion of the thin film formed on the reference pattern is regarded as the reference pattern, and the outer line of the reference pattern and the corresponding alignment are defined. The distance between the inner line of the pattern and / or the distance between the inner line of the reference pattern and the corresponding outer line of the matching pattern may be determined on one side and the other side (the aforementioned x) with respect to the center of the reference pattern. by measuring out with equivalent) in ₁ side and x ₂ side, a method of performing accurate measurements of registration of the resist pattern relative to the reference layer, a reference shape putter A dummy pattern (a pattern not used for measurement) which is similar to the pattern and satisfies the following expressions (1) and (2) is formed inside and outside the reference pattern as a part of the reference mark, and this reference mark is formed. A method of measuring overlay accuracy, wherein the method is used to measure the interval.

L _s = L _s1 ‥‥ (1) 1 ≦ (L _s / W _ss ) ≦ 5 ‥‥ (2) (W _ss : width of reference pattern, L _s : outer line of reference pattern and According to the method of the present invention, the distance between the inner line of the dummy pattern and the inner line of the reference pattern and the outer line of the dummy pattern corresponding to the distance L _s1 : By forming the dummy pattern so as to satisfy the expression (1), the pattern formation density of the reference layer is the same between the inside and outside of the reference pattern. Becomes the same inside and outside the reference pattern. As a result, the degree of inclination of the side wall portion of the thin film outside the reference pattern becomes the same on one side and the other side of the reference pattern. Similarly, the inclination of the side wall of the thin film inside the reference pattern is also
It is the same on one side and the other side of the reference pattern.

As a result, one side of the reference pattern (x
It is possible to reduce the difference in the measurement accuracy of the distance in _one side) and the other side (x ₂ side), can be superimposed with high measurement accuracy than the prior art to measure the accuracy. However, the ratio (L _s ) of the distance L _s (= L _s1 ) between the reference pattern and the dummy pattern to the width W _ss of the reference pattern.
If / W _ss ) is less than 1, the distance between the reference pattern and the dummy pattern is too small, and it is difficult to form a recess at a position between the reference pattern and the dummy pattern of the thin film formed thereon. . Along with this, the measurement in which the convex portion of the thin film formed on the reference pattern is regarded as the reference pattern cannot be performed accurately.

When the ratio (L _s / W _ss ) exceeds 5, the distance between the reference pattern and the dummy pattern is too large, and the effect as the dummy pattern is lost. Further, the size of the entire reference mark becomes too large, which is not practical. Also, in the reference mark, the width of the dummy pattern and the width of the reference pattern do not necessarily have to be equal,
Preferably, they are equal.

In the method of the present invention, a dummy pattern (a pattern not used for measurement) having a shape similar to the matching pattern and satisfying the following equations (3) and (4) is used.
It is preferable that the gap is formed inside and outside the alignment pattern as a part of the alignment mark, and the interval is measured using the alignment mark. L _a = L _a1 ‥‥ (3) 1 ≦ (L _a / W _as ) ≦ 5 ‥‥ (4) (where, W _{as is} the width of the matching pattern, and L _{a is} the outer line of the matching pattern and corresponds to this. The distance from the inner line of the dummy pattern, L _a1 : the distance between the inner line of the alignment pattern and the corresponding outer line of the dummy pattern) Since it is obtained by coating, a difference may occur depending on the formation position in the radial direction within the wafer. On the other hand, by providing the dummy pattern on both sides of the alignment pattern of the alignment mark under the above-described conditions, the difference due to the formation position in the radial direction in the wafer is suppressed. Lines can be formed uniformly irrespective of the formation position of the alignment pattern. As a result, the difference in the measurement accuracy of the distance between one side and the other side of the reference pattern can be made smaller, so that the overlay accuracy can be measured with higher measurement accuracy.

Further, alignment marks (resist patterns)
When the portion of the thin film patterned by etching through is used as a reference mark in the next step, by setting the alignment mark to have a dummy pattern under the above-described conditions, a reference mark that can be used in the method of the present invention is formed. It can be easily formed. That is, in this alignment mark, L _a (the distance between the outer line of the alignment pattern and the corresponding inner line of the dummy pattern) and L a
_{Since a1} (the distance between the inner line of the alignment pattern and the corresponding outer line of the dummy pattern) is equal, the thin film portion patterned by etching through the alignment mark (resist pattern) is used as a reference mark for the next process. In this case, a dummy pattern is formed inside and outside the reference pattern so as to satisfy the above equation (1).

[0015] In addition, the combined distance of the mating pattern and the dummy pattern to the width W _as of pattern L _a (= L _a1)
Since the ratio (L _a / W _as ) is 1 or more and 5 or less, when a thin film portion patterned by etching through an alignment mark (resist pattern) is used as a reference mark in the next process, the reference mark The ratio (L _s / W _ss)
Can be set to 1 or more and 5 or less.

In the alignment mark, the width of the dummy pattern is not necessarily equal to the width of the alignment pattern, but is preferably equal. The present invention also provides a reference mark formed on a reference layer and having a pattern of a predetermined width and a predetermined shape (reference pattern), and a resist pattern formed on the reference layer via a thin film, In the overlay accuracy measurement mark including a registration mark having a pattern (alignment pattern) having a predetermined width and a predetermined shape, the reference mark is similar in shape to the reference pattern and has the following formulas (1) and (2). A registration accuracy measurement mark characterized by having a dummy pattern to be satisfied (a pattern not used for measurement) inside and outside a reference pattern.

L _s = L _s1 ‥‥ (1) 1 ≦ (L _s / W _ss ) ≦ 5 ‥‥ (2) (W _ss : width of reference pattern, L _s : outer line of reference pattern and this (L _s1 : distance between the inner line of the reference pattern and the outer line of the corresponding dummy pattern) In the overlay accuracy measurement mark of the present invention, the alignment mark has a shape It is preferable that a dummy pattern (a pattern not used for measurement) similar to the matching pattern and satisfying the following expressions (3) and (4) is provided inside and outside the matching pattern.

[0018] _{L a = L a1 ‥‥ (3} ) 1 ≦ (L a / W as) ≦ 5 ‥‥ (4) ( although, W _{the as:} width of the mating pattern, L _a: combined pattern outside line and which the (L _a1 : distance between the inner line of the matching pattern and the outer line of the corresponding dummy pattern)

[0019]

Embodiments of the present invention will be described below. The overlay accuracy measurement mark and the overlay accuracy measurement method according to the first embodiment will be described with reference to FIGS. FIG. 1 is a plan view showing the relationship between the reference mark and the alignment mark. FIG. 2 is a diagram showing the relationship between the reference mark, the thin film, and the alignment mark, and corresponds to a cross-sectional view taken along line AA of FIG.

The overlay accuracy measurement mark of this embodiment comprises a reference mark 10 and an alignment mark 20. The reference mark 10 includes one reference pattern 11, a dummy pattern (a pattern not used for measurement) 3 formed inside the reference pattern 11, and a dummy pattern 4 formed outside the reference pattern 11. Alignment mark 2
0 consists of one matching pattern 21.

The reference pattern 11 is a square frame having a predetermined width W _ss . The shape of the inner dummy pattern 3 is
It has a square frame shape smaller than the reference pattern 11. The outer dummy pattern 4 has a square frame shape larger than the reference pattern 11. The width W _sd of both dummy patterns 3 and 4 is the same as the width W _ss of the reference pattern 11. Distance L _s between the outer line and the inner line of the dummy pattern 4 corresponding to the reference pattern 11, the reference pattern 11
_{Is the} same as the distance L _s1 between the inner line of the dummy pattern 3 and the corresponding outer line of the dummy pattern 3. The ratio of the distance between the reference pattern and the dummy pattern to the width W _ss of the reference pattern _{11 L s (= L s1)} ((L s / W ss)) is 3.

The reference mark 10 is patterned on the insulating layer (reference layer) S simultaneously with the main pattern. After forming the aluminum thin film H on the insulating layer S, a resist pattern is formed on the aluminum thin film H. At this time, the alignment mark 20 is formed as a part of the resist pattern simultaneously with the main pattern.
Here, by forming the dummy patterns 3 and 4 inside and outside the reference pattern 11 under the above conditions,
As shown in FIG. 2, the pattern formation density of the insulating layer S is the same between the inside and outside of the reference pattern 11 (in the x direction, on the left and right sides of each of the reference patterns 11a and 11b). Therefore, in the convex portion Ht of the aluminum thin film H on the upper part of the reference pattern 11, the degree of inclination of the inner side walls Hau and Hbu and the degree of inclination of the outer side walls Has and Hbs become the same.

[0023] As a result, the reference pattern 11b of the inclined degree and x ₂ side of the inner wall portion Hau reference pattern 11a of x ₁ side
Has the same inclination degree of the inner wall portion Hbu. The inclination degree of the outer wall portion Has the reference pattern 11a of x ₁ side and x ₂
The inclination degree of the outer wall portion Hbs of the reference pattern 11b on the side becomes the same. The matching pattern 21 has the same width as the reference pattern 11 and has a square frame shape larger than the dummy pattern 4 outside the reference pattern 11.

[0024] Using the mark 20 together with the reference mark 10, the convex portion Ht formed in the upper portion of the reference pattern 11 of the thin film H is regarded as a reference pattern 11, for the x-direction, the x ₁ side reference pattern measurement and distance x ₁ between the inner line of the combined pattern 21a, the distance x ₂ between the inner line of the combined pattern 21b corresponding thereto and the outer line of the reference pattern 11b of the x ₂ side corresponding to the outside line and which of 11a I do. Then, the difference (x
₁₋ x ₂ ) is calculated as the shift amount in the x direction.

[0025] Here, as described above, in the reference pattern 11b of the reference pattern 11a and x ₂ side of the x ₁ side, since the thin film of the outer wall portion Has, the degree of inclination of Hbs are the same, x measurement accuracy between ₁ and x ₂ are the same. as a result,
Measurement of overlay accuracy can be performed with higher measurement accuracy than before. Similarly, in the y direction, the intervals y ₁ and y ₂ are measured, and the difference between these measured values (y ₁ −
By calculating y ₂ ) as a shift amount in the y direction, it is possible to measure the overlay accuracy with higher measurement accuracy than in the past.

FIG. 3 is a plan view showing an overlay accuracy measurement mark according to the second embodiment. In this overlay accuracy measurement mark, the reference mark 10 has two reference patterns 1.
This is an example of the case where both reference patterns 11 and 12 are included.
12, dummy patterns 3 to 6 are formed inside and outside. The alignment mark 20 is composed of one alignment pattern 21, and this alignment pattern 21 is
Is formed between the dummy pattern 4 outside the reference pattern 12 and the dummy pattern 5 inside the reference pattern 12. The matching pattern 21 has the same width as the reference pattern 11 and has a square frame shape larger than the dummy pattern 4 outside the reference pattern 11.

The reference pattern 11 and the dummy patterns 3 and 4 on both sides thereof are the same as in the first embodiment. The reference pattern 12 has the same width W _ss as the reference pattern 11 and has a square frame shape larger than the matching pattern 21. The shape of the inner dummy pattern 5 is a square frame smaller than the reference pattern 12. The shape of the outer dummy pattern 6 is a square frame larger than the reference pattern 12.
The width W _sd of both dummy patterns 5 and 6 is equal to the width of the reference pattern 12.
_{Is the} same as the width W _ss .

The distance L _s between the inner line of the dummy pattern 6 corresponding to the outside line and this reference pattern 12,
It is the same as the distance L _s1 between the inner line of the reference pattern 12 and the corresponding outer line of the dummy pattern 5. The ratio of the distance L _s (= L _s1 ) between the reference pattern and the dummy pattern to the width W _ss of the reference pattern 12 ((L _s /
W _ss )) is 3.

Using the reference mark 10 (10A, 10B) and the alignment mark 20, the reference pattern 1 of the thin film H is used.
The protrusions formed on the upper portions of the reference patterns 11 and 12
Assuming No. 12, the following measurement is performed in the x direction.
For x ₁ side, the interval x between the inner line of the combined pattern 21 corresponding to the outside line and this reference pattern 11
₁₁ and the distance x ₁₂ between the inner line of the reference pattern 12 and the corresponding outer line of the matching pattern 21 are measured. For x ₂ side, the interval x ₂₂ between the outer line of the combined pattern 21 inside the line spacing x ₂₁ and the reference pattern 12, the inner line of the combined pattern and corresponding to the corresponding to the outside line and this reference pattern 11
Is measured.

And x₁₁And x₁₂X₁age
And x_{twenty one}And x_{twenty two}X_TwoCalculated as
(X₁-X_Two) Is calculated as a shift amount in the x direction.
You. Here, as described in the first embodiment, the reference pattern
X of 11₁₁Side and x_{twenty one}The degree of inclination of the outer wall of the thin film between the side and the side
Since the case is the same, x₁₁And x_{twenty one}And the same measurement accuracy
Become. In addition, the reference pattern 12
As described in one embodiment, x₁₂Side and x_{twenty two}Side and in thin film
Since the degree of inclination of the inner side wall portion becomes the same, x ₁₂And x_{twenty two}When
The measurement accuracy becomes the same. As a result, higher measurement
The overlay accuracy can be measured with a constant accuracy.

Similarly, in the y direction, the intervals y ₁₁ ,
By measuring y ₁₂ , y ₂₁ , and y ₂₂ , the overlay accuracy can be measured with higher measurement accuracy than before. FIG. 4 is a plan view showing an overlay accuracy measurement mark according to the third embodiment. This overlay accuracy measurement mark differs from the second embodiment only in the configuration of the alignment mark 20. This alignment mark 20 is one alignment pattern 2
1, a dummy pattern 7 formed inside the matching pattern 21, and a dummy pattern 8 formed outside the matching pattern 21.

The alignment pattern 21 is a square frame having a predetermined width W _as . The shape of the inner dummy pattern 7 is a square frame smaller than the matching pattern 21. The shape of the outer dummy pattern 8 is a square frame larger than the matching pattern 21. Width W _ad both dummy patterns 7 and 8 are the same as the width W _{the as} the combined pattern 21. Distance L _a between the inner line of the dummy pattern 8 to the outside line of the combined pattern 21 and corresponding thereto is the same as the distance L _a1 of the outer lines of the dummy patterns 7 to the inner lines of the combined pattern 21 and correspondingly . The ratio of the combined distance between the reference pattern and the dummy pattern to the width W _{the as} pattern _{21 L a (= L a1)} ((L a /
W _as )) is 3.

According to this embodiment, the alignment pattern 2
Since the dummy patterns 7 and 8 are also formed inside and outside 1, the outer line and the inner line of the matching pattern 21 are uniformly formed regardless of the formation position of the matching pattern 21 as described above. Therefore, it is possible to measure the overlay accuracy with higher measurement accuracy than in the case of the second embodiment.

[0034]

As described above, according to the overlay accuracy measuring method and the overlay accuracy measurement mark of the present invention, the overlay accuracy can be measured with higher accuracy than before.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining an overlay accuracy measurement mark and an overlay accuracy measurement method according to a first embodiment, and is a plan view showing a relationship between a reference mark and an overlay mark.

FIG. 2 is a diagram illustrating a relationship between a reference mark, a thin film, and an alignment mark according to the first embodiment, and corresponds to a cross-sectional view taken along line AA of FIG. 1;

FIG. 3 is a plan view showing an overlay accuracy measurement mark according to a second embodiment.

FIG. 4 is a plan view showing an overlay accuracy measurement mark according to a third embodiment.

FIG. 5 is a view showing a relationship between a conventional reference mark, a thin film, and an alignment mark, and corresponds to a cross-sectional view taken along line BB of FIG. 6;

FIG. 6 is a diagram for explaining a conventional example of a method of measuring overlay accuracy, and is a plan view showing a relationship between a reference mark and an alignment mark.

FIG. 7 is a view for explaining another conventional example of the overlay accuracy measuring method, and is a plan view showing a relationship between a reference mark and an alignment mark.

[Explanation of symbols]

 3 Dummy pattern 4 Dummy pattern 5 Dummy pattern 6 Dummy pattern 7 Dummy pattern 8 Dummy pattern 10 Reference mark 20 Matching mark 21 Matching pattern 11 Reference pattern 12 Reference pattern H Aluminum thin film (thin film formed on reference layer) Ht Reference pattern Convex part of thin film formed on top S Insulating layer (reference layer)

Claims (4)

[Claims] 1. A reference mark having a pattern (reference pattern) having a predetermined width and a predetermined shape is formed on a reference layer, and a predetermined pattern having a predetermined width is formed as a part of a resist pattern formed on the reference layer via a thin film. Shape pattern (matching pattern)
Forming a matching mark having the following formula: a convex portion of the thin film formed on the reference pattern is regarded as a reference pattern, and a distance between an outer line of the reference pattern and a corresponding inner line of the matching pattern, and / or a reference pattern Of the resist pattern with respect to the reference layer by measuring the distance between the inner line of the reference pattern and the corresponding outer line of the alignment pattern on one side and the other side with respect to the center of the reference pattern. In the method, a dummy pattern (a pattern not used for measurement) having a shape similar to the reference pattern and satisfying the following equations (1) and (2) is used as a part of the reference mark, inside and outside the reference pattern. Wherein the distance is measured using the fiducial mark. L _s = L _s1 ‥‥ (1) 1 ≦ (L _s / W _ss ) ≦ 5 ‥‥ (2) (W _ss : width of the reference pattern, L _s : outer line of the reference pattern and its corresponding Distance between inner line of dummy pattern, L _s1 : distance between inner line of reference pattern and outer line of corresponding dummy pattern) 2. A dummy pattern (a pattern not used for measurement) having a shape similar to the matching pattern and satisfying the following formulas (3) and (4) is formed inside and outside the matching pattern as a part of a matching mark. 2. The method according to claim 1, wherein the distance is measured using the alignment mark. L _a = L _a1 ‥‥ (3) 1 ≦ (L _a / W _as ) ≦ 5 ‥‥ (4) (where, W _{as is} the width of the matching pattern, and L _{a is} the outer line of the matching pattern and corresponds to this. Distance from inner line of dummy pattern, L _a1 : distance between inner line of matching pattern and outer line of corresponding dummy pattern) 3. A reference mark formed on the reference layer and having a pattern (reference pattern) having a predetermined width and a predetermined shape, and a resist pattern formed as a part of a resist pattern formed on the reference layer via a thin film. In an overlay accuracy measurement mark composed of an alignment mark having a pattern (alignment pattern) having a predetermined width and a predetermined shape, the reference mark is similar in shape to the reference pattern and has the following formulas (1) and (2). A registration accuracy measurement mark characterized by having a dummy pattern to be filled (a pattern not used for measurement) inside and outside a reference pattern. L _s = L _s1 ‥‥ (1) 1 ≦ (L _s / W _ss ) ≦ 5 ‥‥ (2) (W _ss : width of the reference pattern, L _s : outer line of the reference pattern and its corresponding Distance between inner line of dummy pattern, L _s1 : distance between inner line of reference pattern and outer line of corresponding dummy pattern) 4. The alignment mark has a dummy pattern (a pattern not used for measurement) having a shape similar to the alignment pattern and satisfying the following expressions (3) and (4), inside and outside the alignment pattern. 4. The overlay accuracy measurement mark according to claim 3, wherein: L _a = L _a1 ‥‥ (3) 1 ≦ (L _a / W _as ) ≦ 5 ‥‥ (4) (where, W _{as is} the width of the matching pattern, and L _{a is} the outer line of the matching pattern and corresponds to this. Distance from inner line of dummy pattern, L _a1 : distance between inner line of matching pattern and outer line of corresponding dummy pattern)