JPH04237115A - Monitoring method for accuracy of lithography pattern - Google Patents

Abstract

PURPOSE:To easily inspect the accuracy of lithography pattern. CONSTITUTION:A monitor pattern region, to be used for monitoring of accuracy, is arranged in the region of exposure, this monitor pattern region is divided into a plurality of fields 4 and 6 which are overlapping with each other. Checking patterns 11A and 11B are formed on the overlapped part 10 of the fields 4 and 6, and the positional accuracy of the checking patterns 11A and 11B, drawn by exposing the above-mentioned fields 4 and 6, is measured.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for monitoring the accuracy of photomask writing or wafer direct writing used in the manufacture of semiconductor devices.

0002

2. Description of the Related Art When manufacturing semiconductor devices such as integrated circuits, pattern formation is generally performed using photolithography technology. In recent years, as the degree of integration of semiconductor devices has increased, photomasks are required to have improved quality accuracy such as pattern accuracy and overlay accuracy, and the manufacturing process has also become more complex. For this reason, an electron beam exposure apparatus is used, which allows easy microfabrication and can form photomask patterns with high precision and high speed. Although there are various types of electron beam exposure apparatuses, variable shaped beam vector scan type exposure apparatuses, which can form patterns with higher precision, have come to be used instead of the conventional spot beam raster scan type.

[0003] Here, an exposure method using a variable shaped beam vector scan method will be explained. As shown in FIG. 9, the photomask (21) has a plurality of chip parts (23), and as shown in FIG. (30) is sequentially exposed to light to expose each chip portion (23), thereby forming a pattern on the entire surface of the photomask (21). Note that, as shown in FIG. 11, each field (30
), the pattern is divided into shots (31) which are smaller areas, and exposure is performed using each shot (31) as a unit. Basically, it is divided into rectangular shots like the shot (32), but if a trapezoidal figure (33) is generated due to a diagonal pattern etc., it is divided into rectangular shots as shown in Fig. 12 in order to accurately form the diagonal part. Trapezoid (33
) is further divided into smaller rectangular shots (34), and the rectangular shots (34) are exposed while overlapping each other.

0004

[Problems to be Solved by the Invention] In this way, the pattern data of one chip part (23) consists of a large number of fields (
The pattern data within the field (30) is further divided into a number of shots (31) and exposed. Therefore, the drawing accuracy of the joint between adjacent fields (30) in the chip part (23) and the shot (31)
The dimensional accuracy of the pattern within the field (30) formed by the combination of the above is an important element in an electron beam exposure apparatus, and it is required to maintain these dimensions with high precision. However, since there is no conventional method for measuring and inspecting drawing accuracy, there has been a problem in that it is difficult to manage highly accurate pattern formation, and it is not possible to improve the yield of products.

The present invention has been made to solve the problems of the prior art, and an object of the present invention is to provide a method for monitoring the accuracy of a drawn pattern, which allows easy inspection of the drawing accuracy.

[0006]

[Means for Solving the Problems] A drawing pattern accuracy monitoring method according to the present invention includes arranging a monitor pattern area for accuracy monitoring within an exposure area, and forming a plurality of fields overlapping each other in this monitor pattern area. In this method, a plurality of check patterns are formed in the overlapping portions of the plurality of fields, and the position accuracy of the plurality of check patterns drawn by exposing the plurality of fields is measured.

[0007]

[Operation] In the present invention, a check pattern is formed in the overlapping portion of a plurality of fields in the monitor pattern area, and the positional accuracy of the drawn check pattern is measured to confirm the drawing accuracy.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a plan view showing a photomask produced by a drawing pattern accuracy monitoring method according to an embodiment of the present invention. First, on the surface of a photomask (1) made of, for example, a glass plate, a plurality of chip parts (3) that will become the main pattern are arranged, and a monitor pattern area for precision monitoring ( 2) Place. Next, as shown in FIG. 2, the monitor pattern area (2) is divided into six fields (4) to (9). Among these, fields (4) to (7) have an overlapping portion (10) that partially overlaps each other. For example, the shaded area in FIG. 2 indicates the overlap between fields (4) and (5). Also, field (8
) and (9) are respectively arranged in the center of the monitor pattern area (2) so as to completely overlap each other, and partially overlap with other fields (4) to (7).

A check pattern is formed in each of the overlapping portions of fields (4) to (9). Various check patterns can be considered, but for example, as shown in Figure 3, fields (4) and (6)
) are rectangular check patterns of the same size (
11A) and (11B), and these patterns (
11A) and (11B) are brought into contact at the overlapping portion (10) of fields (4) and (6). Such check patterns (11A) and (11B)
After creating the data, a check pattern (
11A) and (11B) are drawn and formed. By observing the condition of the bonding between the formed patterns (11A) and (11B), it is possible to qualitatively test the accuracy of the connection position between fields (4) and (6), and further based on the results. Check pattern (11A) and (11B)
The drawing accuracy of the main pattern formed in the same process is checked. That is, two check patterns (11
The better the bondability of A) and (11B), the more the field (
The connection position accuracy between 4) and (6) is high, and the drawing accuracy of this pattern is determined to be high.

Further, instead of or in addition to the check patterns (11A) and (11B), a circular check pattern (12A) as shown in FIG.
4), a rectangular check pattern (12B) located at the center of this annular pattern (12A) may be formed in each field (6). After drawing such patterns (12A) and (12B), if the distance between the rectangular pattern (12B) and the annular pattern (12A) on both sides of the rectangular pattern (12B) is measured in the X direction, the difference between these measured values can be reduced to 1/2. The obtained value becomes the field connection position accuracy in the X direction. Similarly, field connection position accuracy in the Y direction can be quantitatively determined.

As shown in FIG. 4, a check pattern (1
If 5A) and (15B) are formed in fields (4) and (6) and a vernier is drawn in the overlapped part (10), it is possible to quantitatively determine the accuracy of the connection position of the fields by visual inspection. can. Furthermore, as shown in FIG. 5, check patterns (15A) and (15B)
) in the direction perpendicular to the second check pattern (16
A) and (16B) respectively in fields (4) and (
6) and draw two sets of verniers, it becomes possible to determine the accuracy of the connection position in both the X and Y directions of the field.

As shown in FIG. 6, a check pattern (13A) consisting of a pair of parallel rectangular patterns is formed near the periphery of the field (6), and also near the center of the field (8). A check pattern (13B) consisting of a pair of rectangular patterns is formed so that these check patterns (13A) and (13B) are alternately located in the overlapping portion of fields (6) and (8). It's okay. By measuring the positional accuracy of these drawn patterns (13A) and (13B), it is possible to determine the variation in dimensions within the field due to deflection aberration.

Furthermore, as shown in FIG.
) is formed in the center of the field (14A), and the above pattern (14A) is formed in the field (9) that completely overlaps with this field (8).
A rectangular check pattern (
14B) may be formed. Then, the field (8) is exposed at the beginning of a series of exposures, and the check pattern (1) is exposed.
4A), then expose the main pattern, etc., and finally expose field (9) to draw the check pattern (
14B). By measuring the relative positions of the patterns (14A) and (14B) drawn in this way in the same manner as the check patterns (12A) and (12B) shown in FIG. It becomes possible to determine drift, that is, positional deviation.

When performing multiple shifted exposure of rectangular shots to draw a trapezoidal figure, as shown in FIG. 8, a triangular or trapezoidal check pattern (17A) is placed on one of a pair of overlapping fields. and the above pattern (17) in the other field.
It is effective to form a triangular or trapezoidal check pattern (17B) having a hypotenuse that joins the hypotenuse of A). Check pattern (17A) and (1
7B), a rectangular pattern is formed by the combination of these, and by measuring the lengths L1 and L2 of this rectangular pattern in the vertical and horizontal directions, the positional accuracy of the hypotenuse of the trapezoid to be drawn can be determined. and the stacking accuracy of rectangular shots can be determined.

Note that in the photomask (1) shown in FIG. 1, the monitor pattern area (2) is placed at one location outside the chip portion (3), but similar monitor pattern areas (2) may be placed at multiple locations. By arranging them and determining the drawing accuracy for each, it is possible to monitor with higher precision. Further, the monitor pattern area may be set inside the chip section (3) instead of outside the chip section (3). As the chip pattern formed in the monitor pattern area (2), it is possible to achieve the same effect even if a pattern having a shape other than the patterns illustrated in FIGS. 3 to 8 is used. Furthermore, although the pattern shape of the photomask (1) was described in the above embodiment, if a wafer is used instead of the photomask (1), the accuracy monitoring method of the present invention can be similarly applied to wafer direct writing. can.

[0016]

As explained above, in the present invention, a monitor pattern area for precision monitoring is arranged within the exposure area, and this monitor pattern area is divided into a plurality of fields that overlap each other. Check patterns are formed in the overlapped areas of multiple fields, and the positional accuracy of multiple check patterns drawn by exposing multiple fields is measured, making it easy to inspect the drawing accuracy. becomes.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a photomask produced by a drawing pattern accuracy monitoring method according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a monitor pattern area arranged on the photomask of FIG. 1;

FIG. 3 is a plan view showing an example of a check pattern formed in a monitor pattern area.

FIG. 4 is a plan view showing another example of a check pattern.

FIG. 5 is a plan view showing another example of a check pattern.

FIG. 6 is a plan view showing another example of a check pattern.

FIG. 7 is a plan view showing another example of a check pattern.

FIG. 8 is a plan view showing another example of a check pattern.

FIG. 9 is a plan view showing a conventional photomask.

FIG. 10 is an enlarged view of part A in FIG. 9;

FIG. 11 is a plan view showing a conventional method of exposing a chip portion.

FIG. 12 is a plan view showing a conventional trapezoid pattern exposure method.

[Explanation of symbols]

1 Photomask 2 Monitor pattern area 4 Field 5 Field 6 Field 7 Field 8 Field 9 Field 10 Overlapping part 11A Check pattern 11B Check pattern 12A Check pattern 12B Check pattern 13A Check pattern 13B Check pattern 14A Check pattern 14B Check pattern 15A Check pattern 15B Check pattern 16A Check pattern 16B Check pattern 17A Check pattern 17B Check pattern

Claims (1)

[Claims] 1. A monitor pattern area for accuracy monitoring is arranged within the exposure area, and this monitor pattern area is divided into a plurality of fields that overlap each other,
Accuracy of a drawing pattern, characterized in that a check pattern is formed in each of the overlapping portions of the plurality of fields, and the position accuracy of the plurality of check patterns drawn by exposing the plurality of fields is measured. Monitoring method.