JP2000340482A - Exposure method and exposure apparatus using this method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To measure the joining accuracy of shots with high accuracy. SOLUTION: A predetermined area on a substrate is exposed by a shot 1 including a mark 1, then the substrate is positioned, and a predetermined area on the substrate is exposed by a shot 2 including a mark 2. The mark 1 and the mark 2 are formed at a joint between the shot 1 and the shot 2. For this reason, the mark 1 image 110 and the mark 2 image 12
0 are superimposed and formed. Here, the mark 2 image 120 is formed inside the mark 1 image 110. For this reason, by measuring the position of the mark 2 image formed inside the mark 1 image, the joining accuracy is measured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an exposure method and an exposure apparatus, and more particularly, to an exposure method for forming a pattern by connecting a plurality of shots in a photolithography process of semiconductor manufacturing and an exposure apparatus using the method.

[0002]

2. Description of the Related Art Semiconductor devices and liquid crystal displays (hereinafter, referred to as "liquid crystal displays").
In a device manufacturing process such as an LCD, there is a photolithography process of transferring a pattern onto a substrate. In the photolithography process, it is very important to match a joint between adjacent shots. For this reason, in an exposure apparatus that performs a photolithography process, a method is used in which the state of shot connection is measured, and the result is fed back as a correction value for connection to maintain the accuracy of connection.

There is a caliper vernier as a monitor for measuring such a shot joining accuracy, and the measurement is performed by visual observation with a microscope. The measurement of the joining accuracy using a vernier caliper will be described. FIG. 4 is a diagram showing a conventional method for measuring the joining accuracy using a vernier caliper. (A) is a top view showing connection of shots. A shot 310 and B shot 3
Reference numeral 20 denotes an adjacent shot having a vernier caliper at a connecting portion. (B) is a monitor screen obtained by enlarging a vernier caliper with a microscope in order to measure joining accuracy. The vernier caliper shown in the figure is a straight line formed in shots and arranged in units of 0.1 μm. The joining accuracy is measured by the displacement monitor 331 in the X direction and the displacement monitor 332 in the Y direction. If the connection between the A shot 310 and the B shot 320 is exactly the same, X
Straight line 331a at the center of the direction shift monitor 331
And a straight line 33 at the center of the displacement monitor 332 in the Y direction.
2a intersects. For example, when the displacement in the Y direction is measured, the displacement in the Y direction is determined by the displacement monitor 331 in the X direction.
Is measured by determining which straight line of the shift monitor 331 in the Y direction is located on the straight line connecting the midpoints of the straight lines forming the line and the extension line thereof. That is, the displacement monitor 3 in the X direction
31 and a straight line 3 at the center of the displacement monitor 332 in the Y direction on an extension of the straight line connecting the midpoints of the straight lines forming
If there is 32a, there is no shift in the Y direction. The shift amount can be measured in 0.1 μm units depending on which straight line of the shift monitor 331 in the Y direction exists at this position. The shift amount can be calculated for the X direction in the same procedure.

[0004]

However, the conventional exposure method and exposure apparatus described above have a problem in that the measurement of shot joining accuracy cannot be performed with high accuracy.

For example, when the caliper vernier described above is used, the amount of deviation can be determined only in units of 0.1 μm. For this reason, it is not possible to take measures for improving the connection accuracy in the exposure apparatus, and a semiconductor element defect may occur due to insufficient alignment accuracy. For example, in the case of the LCD, if the pattern of the joint of the shots becomes thicker or thinner than the pattern other than the joint due to the accuracy of the joint, a defect occurs at the pixel of the joint. In addition, for a product such as a linear sensor that requires high accuracy in joining shots, it is an important issue to measure the joining of shots with high accuracy.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an exposure method capable of measuring shot joining accuracy with high accuracy, and an exposure apparatus using the method.

[0007]

According to the present invention, there is provided an exposure method for forming a pattern by joining a plurality of shots in a photolithography process of semiconductor manufacturing, and projecting and exposing the pattern on a substrate. Forming, in a first shot, a first pattern and a first mark for detecting a joining error having a fixed positional relationship with the first pattern, and projecting the first shot onto the substrate by exposure And a second shot having a predetermined positional relationship with the first shot.
Forming a second mark for detecting a joining error at a position overlapping with the first mark by joining the second shot with the second pattern, and projecting and exposing the second shot onto the substrate; A procedure for measuring the joining accuracy between the first shot and the second shot based on the shape of an image in which the first mark image and the second mark image formed above are superimposed. An exposure method is provided.

In the exposure method of such a procedure, the first shot in which the first pattern and the first mark having a predetermined positional relationship are formed, and the position where the second pattern overlaps the first mark. A second mark having a relationship is formed, and the first shot and the second shot are projected and exposed on the substrate. A first mark image and a second mark image are formed so as to overlap each other at a joint of shots on the substrate. By measuring the shape formed by overlapping the first mark image and the second mark image, the joining accuracy between the first shot and the second shot is measured.

Further, a pattern is formed by connecting a plurality of shots in a photolithography process of semiconductor manufacturing.
In an exposure apparatus for projecting and exposing a pattern on a substrate, a first shot in which a first pattern and a first mark for detecting a joining error in a fixed positional relationship with the first pattern are formed; A second shot having a predetermined positional relationship with the first shot in which a second mark for detecting a joining error is formed at a position overlapping with the first mark by joining together with the second pattern;
Exposure means for performing projection exposure on a substrate by joining the shot and the second shot, and the first mark image and the second mark image formed on the substrate on which the projection exposure has been performed. An exposure apparatus, comprising: a joining error measuring unit for measuring a shape to be formed;
Is provided.

[0010] The exposure apparatus having the above-described configuration is configured to perform the first shot in which the first mark is formed and the second shot in which the second mark overlapping with the first mark is formed. Exposure is performed on the substrate by exposure means.
At this time, the first mark image and the second mark image are formed so as to overlap each other at the joint of the shots on the substrate. The joining error measuring means measures a shape formed by overlapping the first mark image and the second mark image,
Measure the joining accuracy.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. On the substrate coated with resist,
An exposure method and an exposure apparatus for exposing the second shot (hereinafter, shot 2) by connecting the shot (hereinafter, shot 1) with the second shot will be described.

The exposure apparatus is, for example, a reduction projection type exposure apparatus (hereinafter, referred to as a stepper). The exposure apparatus performs projection exposure of a pattern onto a substrate, and the joining error measuring means performs measurement of a joining error. And In the photolithography process, a resist film is formed on a substrate having a layer to be processed formed on a surface thereof, and a pattern of a reticle or a mask is projected and exposed by exposure means. A pattern area exposed at one time is called a shot. In this projection exposure, a pattern composed of a plurality of shots is exposed by connecting the shots. That is, after exposing the pattern formed on the reticle to a predetermined region of the substrate, the substrate is stepped by a predetermined distance, and the exposure is repeated again, that is, the so-called step-and-repeat exposure is performed. The joining error measuring means measures an error of the joined shot.

The pattern to be exposed includes shot 1 and shot 2. In the shot 1 and the shot 2, a mark for detecting a connection error is provided at a connection portion between the shot 1 and the shot 2 together with the pattern. The mark is separated from the pattern formed on the shot, and has a certain positional relationship with the pattern. The mark formed on shot 1 is referred to as mark 1 and the mark formed on shot 2 is referred to as mark 2.

First, the mark 1 formed on the shot 1 will be described. FIG. 1 is a diagram showing a joining error detection mark formed on a first shot according to an embodiment of the present invention. (A) is a top view of a mark image projected and exposed on a substrate, and (b) is a cross-sectional view of the substrate.

The mark 1 of shot 1 is formed by a combination of a resist removal pattern for removing the resist 210 applied to the processing target layer 220 on the substrate 230 and a resist remaining pattern for leaving the resist. The resist removal pattern and the resist remaining pattern have similar shapes having the same center. Here, it has a box shape. The mark 1 image (110) formed on the substrate by exposing the shot 1 including the mark 1 is a box type having a resist remaining pattern inside as shown in the figure. As shown in the cross-sectional view, the resist is removed from the mark 1 image 110 portion.

Next, the mark 2 formed on the shot 2 will be described. FIG. 2 is a diagram illustrating a joining error detection mark formed on a second shot according to an embodiment of the present invention. (A) is a top view of a mark image projected and exposed on a substrate, and (b) is a cross-sectional view of the substrate.

The mark 2 of the shot 2 is formed by a combination of a resist removal pattern for removing the resist 210 applied to the processing target layer 220 on the substrate 230. The resist removal pattern is a box type similar to the above-described mark 1 resist remaining pattern, and is smaller than the mark 1 resist remaining pattern. When the joining of shot 1 and shot 2 match, the center of mark 1
The centers of the marks 2 coincide. The mark 2 image (120) formed on the substrate by exposing the shot 2 including the mark 2 is box-shaped as shown in the drawing. Further, as shown in the cross-sectional view, the resist is removed from the mark 2 image 120 part.

In practice, a predetermined area of the substrate is exposed by a shot 1 including a mark 1, and then the substrate is positioned and a predetermined area of the substrate is exposed by a shot 2 including a mark 2. Will be As described above, since the mark 1 and the mark 2 are formed at the joint of the shot 1 and the shot 2, an image in which the mark 1 and the mark 2 are superimposed is formed on the substrate. In this case, mark 1
The mark 2 image is formed inside the image. Therefore, by measuring the position of the mark 1 image formed inside the mark 1 image, the joining accuracy can be measured.

The operation of the joint error measuring means of the exposure apparatus described above and the method of measuring joint accuracy will be described. FIG. 3 is a diagram showing a method for measuring the joining accuracy of the exposure apparatus according to one embodiment of the present invention. Mark 1 image (110) formed by mark 1 of shot 1
And the mark 2 image (120) formed by the mark 2 of the shot 2 is formed on the substrate so as to overlap the joint portion between the shot 1 and the shot 2.

The joining error is calculated by measuring the width of the inner resist remaining portion (130). The width of the resist remaining portion (130) can be accurately measured by an automatic measuring device. As shown in the figure, the vertical width of the remaining resist 130 is defined as X1 and X2. Further, the widths of the left resist 130 in the left-right direction are Y1 and Y2.
The vertical joining error Xg can be calculated by the following equation.

[0021]

Xg = (X1-X2) / 2 (1) Similarly, the joining error Yg in the left-right direction can be calculated by the following equation.

[0022]

Yg = (Y1−Y2) / 2 (2) When the joining of shots 1 and 2 matches and there is no deviation, X1 = X2, Y1 = Y2, and Xg = 0,
Yg = 0.

When the shot 2 is shifted downward by 1 μm with respect to the shot 1, X1 becomes 1 μm thick and X2 becomes 1 μm.
m thinner. Using equation (1), Xg = 1 is obtained. Similarly, when shot 2 is shifted by 1 μm to the right with respect to shot 1, Y1 becomes 1 μm thick and Y2 becomes 1 μm.
m thinner. Using equation (2) yields Yg = 1.

As described above, by measuring the shape formed by superimposing the mark 1 and the mark 2, it is possible to accurately measure the joining accuracy. Further, if the movement distance of the stepper for each shot is corrected based on the deviation amount obtained in this manner, the deviation amount at the connection of shots can be reduced.

In the above description, the mark for measuring the joining accuracy between shots has a box shape, but the present invention is not limited to this.
It can also be in a donut shape.

[0026]

As described above, according to the present invention, the first shot in which the first pattern and the first mark having a predetermined positional relationship are formed, the second pattern and the first mark are formed. A second mark having an overlapping positional relationship with a second shot in which the second mark is formed is connected and projected onto a substrate. A first mark image and a second mark image are formed on a shot joining portion on the substrate so as to overlap each other, and the accuracy of joining between shots is measured based on the superimposed mark image.

The overlay mark image formed on the substrate is formed in a similar shape such as a donut shape or a box shape, and a closed shape having a predetermined width is formed by the overlay. By measuring the width of this shape, it is possible to accurately measure the shot joining accuracy.

An exposure apparatus using the method of the present invention comprises:
The first shot on which the first mark is formed and the second shot on which the second mark overlapping with the first mark is formed are projected and exposed on the substrate by exposure means. At this time, the first mark image and the second mark image are formed so as to overlap each other at the joint of the shots on the substrate. The joining error measuring means measures a shape formed by overlapping the first mark image and the second mark image, and measures joining accuracy.

The overlay mark image formed on the substrate is formed in a similar shape such as a donut shape or a box shape, and a closed shape having a predetermined width is formed by the overlay. The joining error measuring means can accurately measure the width of the shape formed by the overlapping. This makes it possible to accurately measure the connection accuracy of shots.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a joining error detection mark formed on a first shot according to an embodiment of the present invention;

FIG. 2 is a diagram illustrating a joining error detection mark formed on a second shot according to an embodiment of the present invention;

FIG. 3 is a diagram showing a method of measuring the joining accuracy of the exposure apparatus according to one embodiment of the present invention.

FIG. 4 is a diagram showing a conventional method of measuring joining accuracy using a vernier caliper.

[Explanation of symbols]

110: mark 1 image, 120: mark 2 image, 130: resist remaining, 210: resist, 220: layer to be processed, 2
30 ... substrate

Claims (5)

[Claims] 1. An exposure method for forming a pattern by joining a plurality of shots in a photolithography process of semiconductor manufacturing, and projecting and exposing the pattern on a substrate, wherein the first shot includes a first pattern and the first pattern Forming a first mark for detecting a joining error having a fixed positional relationship with the pattern; projecting and exposing the first shot onto the substrate; and forming a first mark having a predetermined positional relationship with the first shot. Forming a second mark for joining error detection at a position overlapping with the first mark by joining together with the second pattern in the second shot, projecting and exposing the second shot on the substrate, The first mark image formed on the substrate and the second mark image;
An exposure method comprising: measuring a joining accuracy between the first shot and the second shot based on a shape of an image on which the mark image is superimposed. 2. The exposure method according to claim 1, wherein the first mark and the second mark are formed in a similar shape. 3. The mark according to claim 1, wherein the first mark and the second mark are formed in a positional relationship in which the center points of both marks match when the connection between shots matches. Exposure method. 4. The step of measuring the joining accuracy between the first shot and the second shot is performed in the vertical and horizontal directions of a shape formed by overlapping the first mark and the second mark. 2. The exposure method according to claim 1, further comprising a step of measuring a width in a direction. 5. An exposure apparatus for forming a pattern by joining a plurality of shots in a photolithography process of semiconductor manufacturing and projecting and exposing the pattern on a substrate, wherein the first pattern, the first pattern and a fixed position A first shot formed with a first mark for detecting a joining error in a relationship, and a second mark for detecting a joining error at a position overlapping with the first mark by joining together with a second pattern. A second shot having a predetermined positional relationship with the first shot having formed thereon, an exposing means for joining the first shot and the second shot to perform projection exposure on a substrate, and the projection exposure A joint error measuring means for measuring a shape formed by the first mark image and the second mark image formed on the substrate on which Exposure apparatus characterized by.