JPH10177946A - Pattern and method for measuring exposure accuracy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve the reduction of the forming area of an exposure-accuracy measuring pattern and the shortening of the time for measuring the exposure accuracy. SOLUTION: This pattern is an exposure-accuracy measuring pattern 1, which measures the superimposing accuracy of a first exposure region 11, a second exposure region 12 and a third exposure region 13, and linking accuracy of the second exposure region 12 and the third exposure region 13. The pattern 1 comprises a first measuring pattern 21, which is formed with the exposure of the first exposure region 11, a second measuring pattern 22, which is formed with the exposure of the second exposure region 12, and a third measuring pattern 23, which is formed with the exposure of the third exposure region 13. The first measuring pattern 21 is constituted of x-axis patterns 21x1 and 21x2 , and y-axis patterns 21y1 and 21y2 . The second measuring pattern 22 is constituted of x-axis patterns 22x1 and 22x2 and y-axis patterns 22y1 and 22y2 and arranged so as to keep the specified interval from the first measuring pattern 21. The third measuring pattern 23 is arranged at the inner side of the second measuring pattern 22 so as to keep the specified interval from the second measuring pattern 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an exposure accuracy measurement pattern and a measurement method for measuring overlay accuracy and joining accuracy between different exposure regions in a lithography process of manufacturing a semiconductor device.

[0002]

2. Description of the Related Art In a lithography process in the manufacture of semiconductor devices, pattern exposure has been performed using a single exposure apparatus having an exposure area of about 10 μm × 10 μm to 20 μm × 20 μm. However, in recent years, pattern exposure has been performed using a plurality of exposure apparatuses having different exposure areas from the viewpoints of cost reduction of semiconductor device manufacturing and miniaturization of element structures. In addition, due to an increase in the number of required elements due to higher integration and higher functionality of a semiconductor device, a chip size may be larger than an exposure area.

In such a case, as shown in FIG.
It is necessary to align the lower exposure region 31 having a larger exposure area with the upper exposure region 32 having a smaller exposure area in a matrix with high accuracy. In this alignment, in order to ensure the connection of the circuit patterns arranged over the upper exposure region 32,
It is necessary to ensure the joining accuracy between the upper exposure regions 32 as well.

Therefore, the overlay accuracy of the upper exposure region 32 with respect to the lower exposure region 31 and the joining accuracy between the upper exposure regions 32 are measured, and a matching accuracy correction coefficient is calculated based on the measured exposure accuracy. Alignment is being performed.

When measuring the overlay accuracy and the joining accuracy, an overlay accuracy measurement pattern 33 for measuring the overlay accuracy is formed for each of the upper-layer exposure regions 32. A connection accuracy measurement pattern 34 for measuring the connection accuracy at the boundary of each upper layer exposure region 32 is formed separately from 33.

FIG. 4 (1) is a top view and FIG.
As shown in the cross-sectional view B ′,
3 denotes a peripheral pattern 31a formed by exposing the lower exposure area 31 and a peripheral pattern 3a formed by exposing the upper exposure area 32.
1a, and a central pattern 32a formed at the center of 1a. In order to measure the overlay accuracy using the overlay accuracy measurement pattern 33, first, an optical or electron beam scanning type alignment accuracy measuring device is used to shift the center pattern 32a from the peripheral pattern 31a in the x-axis direction ax, Measure bx. Then, the shift amounts ax, bx
From the superposition accuracy Aerrx = (ax-b
x) / 2 is calculated. Further, the overlay accuracy in the y-axis direction is calculated in the same manner as described above.

On the other hand, as shown in FIG. 5, the connection accuracy measurement pattern 34 is composed of measurement patterns 32b, 3 exposed on the upper exposure areas 32 which are exposed next to each other.
2b. These measurement patterns 32b are composed of a portion extending in the x-axis direction and a portion extending in the y-axis direction of the upper layer exposure region 32. In order to measure the connection accuracy using the connection accuracy measurement pattern 34, the measurement pattern 32 between the adjacent upper exposure regions 32 is measured.
spacing cx, d between pattern portions parallel to each other between b and 32b
Measure y and intervals ey and fy. Then, from these intervals, the joining accuracy Serrx = (cx +
dy) / 2-w (w is the design pattern distance). y
Direction connection accuracy Serry = (ey + fy) /
2 is calculated.

[0008]

However, in the above-described exposure accuracy measuring method, a plurality of overlay accuracy measurement patterns for measuring the overlay accuracy between the lower exposure region and each upper exposure region, and the overlapping accuracy measurement patterns between the upper exposure regions are determined. The connection accuracy measurement patterns for measuring the connection accuracy are individually arranged in an irrelevant arrangement state, and the above-described respective measurement patterns are individually provided for each type of the connection accuracy measurement. For this reason, as described above, when the number of types for measuring the alignment accuracy increases, the arrangement positions of the measurement patterns increase, and the ratio of the measurement patterns to the entire chip area increases. Therefore, the arrangement area of the actual device is reduced.

In addition, since the overlay accuracy measurement pattern and the connection accuracy measurement pattern are individually provided for each type for which the alignment accuracy is measured as described above, the measurement for obtaining each alignment accuracy can be performed by disposing the respective measurement patterns. Need to be done in position. For this reason, the movement between the measurement positions and the time required for the measurement increase, and the throughput of the exposure accuracy measurement cannot be secured. This leads to an increase in the wafer processing time, which is one of the factors that lowers the TAT for manufacturing semiconductor devices.

[0010]

SUMMARY OF THE INVENTION The present invention relates to an exposure accuracy measurement pattern and an exposure accuracy measurement method for solving the above problems. That is, the exposure accuracy measurement pattern of the present invention includes the overlay accuracy of the first exposure region and the second exposure region, the overlay accuracy of the first exposure region and the third exposure region, and the second exposure region and the second exposure region. This is an exposure accuracy measurement pattern for measuring the joining accuracy with the three exposure regions, and includes a first measurement pattern, a second measurement pattern, and a third measurement pattern. The first measurement pattern includes a first exposure area, a second
It is formed by exposing the exposure area or the third exposure area. Further, the second measurement pattern is formed by exposing an exposure area different from the first measurement pattern in each of the exposure areas so that a predetermined positional relationship with the first measurement pattern is maintained. Then, the third measurement pattern is different from the first measurement pattern and the second measurement pattern in each of the exposure regions so that a predetermined positional relationship is maintained with respect to the first measurement pattern and the second measurement pattern. It is formed by exposing the exposure area.

The exposure accuracy measuring method according to the present invention is characterized in that, of the first to third measurement patterns, the measurement pattern formed by the exposure of the first exposure region and the measurement pattern formed by the second exposure region are compared. The overlay accuracy between the first exposure area and the second exposure area is measured from the positional relationship. Further, the overlay accuracy of the first exposure region and the third exposure region is measured from the positional relationship between the measurement pattern formed by the exposure of the first exposure region and the measurement pattern formed by the exposure of the third exposure region. . Further, the joining accuracy between the second exposure region and the third exposure region is measured from the positional relationship between the measurement pattern formed by the exposure of the second exposure region and the measurement pattern formed by the exposure of the third exposure region. .

In the above exposure accuracy measurement patterns, all of the measurement patterns formed by exposure of different exposure regions are arranged so as to maintain a predetermined positional relationship.
From this, the positional relationship between the measurement patterns is the positional relationship between the exposure regions, that is, the overlay accuracy between the first exposure region and the second exposure region, and the overlay accuracy between the first exposure region and the third exposure region. And the joining accuracy of the second exposure region and the third exposure region. For this reason, it is not necessary to separately provide an exposure accuracy measurement pattern for measuring each of the above-mentioned alignment accuracy for each alignment accuracy. Therefore, the formation area of the measurement pattern required for measuring each of the alignment accuracy is reduced.

In the above-described exposure accuracy measuring method, each of the exposure accuracy measuring patterns formed of the first, second, and third measurement patterns formed so as to maintain a predetermined positional relationship. The actual positional relationship of the measurement pattern is measured, and the alignment accuracy between the exposure regions is calculated. From this, the measurement of the positional relationship only needs to be performed on the exposure accuracy measurement pattern portion composed of the first measurement pattern, the second measurement pattern, and the third measurement pattern, and can be performed without significantly moving the measurement position. Will be Therefore, the time required for calculating the alignment accuracy is reduced.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of an exposure accuracy measurement pattern and an exposure accuracy measurement method to which the present invention is applied will be described. 1 and 2 are views for explaining an exposure accuracy measurement pattern and an exposure accuracy measurement method using the pattern. FIG. 1A is an enlarged top view of one of the exposure accuracy measurement patterns. 1 (2) is a sectional view taken along the line AA '.

Here, as an example, the semiconductor chip 10
The first exposure region 11 of the first layer having an exposure area approximately equal to the area of the second exposure region 12 to the second layer having an exposure area of about 1/4 of the first exposure region 11. When the fifth exposure area 15 is overlapped, the first exposure area 1
An exposure accuracy measurement pattern and a measurement method for measuring the overlay accuracy of the first exposure region 12 to the fifth exposure region 15 and the joining accuracy between the second exposure region 12 to the fifth exposure region 15 will be described. .

Hereinafter, the configuration of the exposure accuracy measurement pattern 1 will be described in the order of its formation. First, a first exposure region 11 is exposed on a resist film (not shown) on the semiconductor chip 10. After that, a first measurement pattern 21 composed of a resist pattern formed by a development process is formed on the semiconductor chip 10.

The first measurement pattern 21 is provided at a boundary between two exposure regions of a second layer to be formed later. The first measurement pattern 21 includes, for example, two x
Axis pattern 21x _1, 21x ₂ and two y-axis pattern 2
11 ₁ and 21y _2. Here, as an example, it is formed as a so-called rectangular box pattern. Note that the x-axis patterns 21x ₁ and 21x ₂ and the y-axis patterns 21y ₁ and 21y ₂ are line patterns perpendicular to each other.

Next, a resist film is formed on the semiconductor chip 10 on which the first measurement pattern 21 has been formed, and the resist film is exposed in the second exposure region 12. The exposure of the second exposure area 12 is performed so as to overlap a predetermined area of the first exposure area 11. Next, the resist film is superimposed on a predetermined area of the first exposure area 11,
The third exposure area 13 is exposed so that the second exposure area 12 and the second exposure area 12 are joined in a predetermined state. Similarly, the exposure of the fourth exposure area 14 is performed so as to be superimposed on the predetermined area of the first exposure area 11 and connected to the second exposure area 12 in a predetermined state. The fifth exposure region 15 is exposed so as to be superimposed thereon and to be connected with the third exposure region 13 and the fourth exposure region 14 in a predetermined state. Then, the resist film is developed.

The second exposure region 12 and the fifth exposure region 15 are exposed to the second exposure region 12 and the fifth exposure region 15, respectively.
The measurement pattern 22 is formed. Also, the third exposure area 13
The third measurement pattern 23 formed by exposing each of these exposure regions is formed on the third exposure region 14 and the fourth exposure region 14. The second
The measurement pattern 22 and the third measurement pattern 23 are resist patterns.

The second measurement pattern 22 includes the third exposure area 13 in the second exposure area 12 and the fifth exposure area 15.
Is provided on the side edge and the side edge of the fourth exposure region 14 side.
The second measurement pattern 22 includes, for example, two x-axis patterns 22x ₁ and 22x ₂ and two y-axis patterns 22x1
It is composed of a y _1, 22y _2, here and be formed as a so-called box pattern square as an example. Further, the second measurement pattern 22 is arranged so that a predetermined positional relationship with the first measurement pattern 21 is maintained. Here, the second measurement pattern 22 is located at a position surrounded by the first measurement pattern 21.
Are formed by exposure so that an equal interval is maintained in four directions.

The third measurement pattern 23 is the third measurement pattern 23.
In the exposure region 13 and the fourth exposure region 14, they are provided on the periphery on the second exposure region 12 side and the periphery on the fifth exposure region 15 side. The third measurement pattern 23 is formed, for example, as a rectangular island pattern. The third measurement pattern 22 is arranged so that a predetermined positional relationship is maintained with respect to the first measurement pattern 21 and the second measurement pattern 22. Here, the third measurement pattern 23 is formed at a position surrounded by the second measurement pattern 22 by exposure such that an equal interval is maintained between the third measurement pattern 22 and the second measurement pattern 22 in four directions. .

The measurement of the exposure accuracy using the exposure accuracy measurement pattern 1 composed of the first measurement pattern 21, the second measurement pattern 22, and the third measurement pattern 23 is performed as follows. First, the actual positional relationship between the first measurement pattern 21 to the third measurement pattern 23 formed as described above is measured using an optical or electron beam scanning type alignment accuracy measuring device. Here, as the positional relationship, the distance g in the x direction between the first measurement pattern 21 to the third measurement pattern 23 is set.
x to mx are measured as follows.

[0023] gx: distance between the y-axis pattern 22y ₁ and the third measurement pattern 23 second measurement pattern 22, hx: distance between the third measurement pattern 23 and y-axis pattern 22y ₂ of the second measurement pattern 22, jx : distance between the y-axis pattern 22y ₁ and y-axis pattern 21y ₁ of the first measurement pattern 21 second measurement pattern 22, kx: the y-axis pattern 21y ₂ of the first measurement pattern 21 y-axis of the second measurement pattern 22 distance between the pattern 22y _2, lx: a third measurement pattern 23 distance between the y-axis pattern 21y ₁ of the first measurement pattern 21, mx: a third measurement pattern 23 and y-axis pattern 21y ₂ of the first measurement pattern 21 Interval.

Then, the overlay accuracy A1-2x of the first exposure area 11 and the second exposure area 12 in the x-axis direction is calculated as follows. A1-2x = (jx-kx) / 2 Also, the overlay accuracy A1-5x of the first exposure region 11 and the fifth exposure region 15 in the x-axis direction is calculated in the same manner as described above.

Then, the overlay accuracy A1-3x of the first exposure region 11 and the third exposure region 13 in the x-axis direction is calculated as follows. A1-3x = (lx-mx) / 2 Further, the overlay accuracy A1-4x of the first exposure region 11 and the fourth exposure region 14 in the x-axis direction is calculated in the same manner as described above.

Further, the joining accuracy S2-3x in the x-axis direction between the second exposure region 12 and the third exposure region 13 is calculated as follows. S2-3x = (gx-hx) / 2 Further, the joining accuracy S2-4x in the x direction between the second exposure region 12 and the fourth exposure region 14, and the connection between the third exposure region 13 and the fifth exposure region 15. The alignment accuracy S3-5x and the joint accuracy S4-5x in the x-axis direction between the fourth exposure region 14 and the fifth exposure region 15 are calculated in the same manner as described above.

Further, in the same manner as described above, each alignment accuracy in the y direction between the respective exposure regions is calculated.

In the exposure accuracy measurement pattern 1 having the above configuration,
All of the first to third measurement patterns 21 to 23 formed by exposure of different exposure regions are formed by exposure such that a predetermined positional relationship (interval) is maintained. From this, the positional relationship between the first measurement pattern 21 to the third measurement pattern 23 is the first exposure area 11 to the fifth
This shows the arrangement relationship between the exposure regions 15. Therefore, using the exposure accuracy measurement pattern 1, it is possible to measure all the overlaying accuracy and the joining accuracy between the first exposure region 11 to the fifth exposure region 15 as described above, and to measure the above alignment accuracy. It is not necessary to separately provide measurement patterns for performing the measurement.

Specifically, in order to form the exposure accuracy measurement pattern described in the prior art, it is necessary to measure the overlay accuracy of the first exposure region and the second exposure region by exposing the first exposure region. It is necessary to form two measurement turns of a measurement pattern for measuring the overlay accuracy of the first exposure region and the third exposure region. Furthermore, by exposing the second exposure area, the measurement pattern for measuring the overlay accuracy of the second exposure area and the first exposure area and the overlay accuracy of the second exposure area and the third exposure area are determined. It is necessary to form two measurement turns with a measurement pattern for measurement, and similarly, it is necessary to form two measurement patterns by the third exposure.
That is, in the conventional example, six types of measurement patterns were required to measure the overlaying accuracy and the joining accuracy of three different exposure regions.

On the other hand, in order to perform the same measurement in the above embodiment, it is sufficient to form one measurement pattern by exposure of each exposure area, and only three types of measurement patterns are required in total. . For this reason, the total number of measurement patterns for measuring the above-described respective precisions can be minimized.

Further, in the above embodiment, all of the first to third measurement patterns 21 to 23 formed by exposing the first to third exposure regions 11 to 13 are surrounded by the first measurement pattern 21. It is arranged in the state where it was gathered in the part which was done. For this reason, the formation area of the measurement pattern can be minimized.

The first measurement pattern 21 and the second measurement pattern 22 are composed of two x-axis patterns and two y-axis patterns, and the alignment accuracy is measured using these patterns. The accuracy of the measurement can be ensured.

Further, in the above exposure accuracy measuring method, each of the exposure regions 11 to 15 is used as described above using each interval between the first to third measurement patterns 21 to 23 (for example, intervals gx to mx in the x direction). The superimposition accuracy and the joining accuracy between them are calculated. Moreover, the measurement turns are arranged in one place. For this reason, the measurement of the interval is performed without significantly moving the measurement position, and the time required for calculating the alignment accuracy is reduced.

In the above embodiment, the first measurement pattern 21 is formed in the first exposure region 11 of the first layer, and the second measurement pattern 22 is formed in the second exposure region 12 and the fifth exposure region 15 of the second layer. Was formed, and a third measurement pattern 23 was formed in the third exposure region 13 and the fourth exposure region 14 of the second layer. However, the present invention is not limited to the above configuration. The first exposure region 11 having a large exposure area may be the second layer, and the second to fifth exposure regions 12 to 15 may be the first layers. .

Further, a first measurement pattern 21 and a second measurement pattern 2 constituting one exposure accuracy measurement pattern 1
Second, if the third measurement pattern 23 is such that the mutual relationship is maintained in the state described in the above embodiment and each measurement pattern is formed by exposure of a different exposure area,
It is not limited to the above embodiment. However, by forming the first measurement pattern 21 disposed on the outermost side by exposing the first exposure region 11 having a large exposure area, the second layer for forming the exposure accuracy measurement pattern 1 is formed. The overlap width of each exposure region of the eye (the exposure region having a narrow exposure region) can be reduced.

[0036]

As described above, according to the exposure accuracy measurement pattern of the present invention, all the measurement patterns formed by exposing different exposure areas are formed so as to maintain a predetermined positional relationship. In addition, it is possible to minimize the total number of patterns required for measuring the overlay accuracy and the joint accuracy between the exposure regions. For this reason, it is possible to reduce the formation area of the exposure accuracy measurement pattern for measuring the alignment accuracy, and to increase the formation area of the actual pattern.

In the above exposure accuracy measuring method, the exposure accuracy measurement pattern is formed so that a predetermined arrangement state is maintained between all the measurement patterns, so that the alignment accuracy can be reduced without largely moving the measurement position. It is possible to obtain the positional relationship between the measurement patterns on each side for obtaining the following. For this reason, the time required for the exposure accuracy measurement can be reduced, and the throughput of the exposure accuracy measurement can be secured. Therefore, the TAT for manufacturing a semiconductor device can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram (part 1) for explaining an embodiment to which the present invention is applied;

FIG. 2 is a diagram (part 2) for describing an embodiment to which the present invention is applied;

FIG. 3 is a diagram showing a conventional exposure accuracy measurement pattern and measurement method.

FIG. 4 is a diagram showing a conventional overlay accuracy measurement pattern and measurement method.

FIG. 5 is a diagram showing a conventional connection accuracy measurement pattern and measurement method.

[Explanation of symbols]

1 Exposure accuracy measurement pattern 11 First exposure area
12 second exposure area 13 third exposure region 21 first measurement pattern _{21x 1, 21x 2, 22x 1} , 22x 2 y -axis pattern _{21y 1, 21y 2, 22y 1} , 22y 2 y -axis pattern 22 second measurement pattern 23 first 3 measurement patterns

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 21/30 502Z

Claims (3)

[Claims] 1. An overlay accuracy between a first exposure area and a second exposure area, an overlay accuracy between the first exposure area and a third exposure area, and an overlay accuracy between the second exposure area and the third exposure area. An exposure accuracy measurement pattern for measuring the joining accuracy of: a first measurement pattern formed by exposing the first exposure region, the second exposure region, or the third exposure region; A second measurement pattern formed by exposing an exposure area different from the first measurement pattern in each of the exposure areas so that a predetermined positional relationship is maintained; and the first measurement pattern and the second measurement pattern. A third measurement pattern formed by exposure of an exposure area different from the first measurement pattern and the second measurement pattern in each of the exposure areas so that a predetermined positional relationship is maintained with respect to An exposure accuracy measurement pattern characterized by comprising: 2. The exposure accuracy measurement pattern according to claim 1, wherein the first measurement pattern includes two x-axis patterns and the x-axis pattern.
And two y-axis patterns arranged substantially perpendicular to the axis pattern. The second measurement pattern has a predetermined interval with respect to the two x-axis patterns constituting the first measurement pattern. The two y-axis patterns arranged between the x-axis patterns so as to be maintained and the two y-axis patterns constituting the first measurement pattern so that a predetermined interval is maintained between the two y-axis patterns. The third measurement pattern is defined by two x-axis patterns and two y-axis patterns constituting the second measurement pattern. An exposure accuracy measurement pattern, which is disposed at a position surrounded by the x-axis pattern and the y-axis pattern so that the distance between the patterns is maintained. 3. An overlay accuracy between a first exposure area and a second exposure area, an overlay accuracy between the first exposure area and a third exposure area, and an overlay accuracy between the second exposure area and the third exposure area. An exposure accuracy measuring method for measuring a joining accuracy of: forming a first measurement pattern by exposing the first exposure region, the second exposure region, or the third exposure region; Forming a second measurement pattern by exposing an exposure area different from the first measurement pattern so that a predetermined arrangement state is maintained with respect to the first measurement pattern; And forming a third measurement pattern by exposure of an exposure area different from the second measurement pattern so that a predetermined positional relationship is maintained with respect to the first measurement pattern and the second measurement pattern. The positional relationship between the measurement pattern formed by the exposure of the first exposure region and the measurement pattern formed by the exposure of the second exposure region in the first exposure region. Calculating the overlay accuracy between the measurement pattern formed by the exposure of the first exposure region and the measurement pattern formed by the exposure of the third exposure region. The positional relationship is measured, the overlay accuracy of the first exposure region and the third exposure region is calculated from the measured positional relationship, and the measurement formed by the exposure of the second exposure region in each of the measurement patterns Measuring a positional relationship between the pattern and a measurement pattern formed by exposure of the third exposure region, and calculating a joining accuracy between the second exposure region and the third exposure region from the measured positional relationship. When Exposure accuracy measurement how.