WO2017007072A1

WO2017007072A1 - Overlay mark, overlay measurement method using same, and method for manufacturing semiconductor device

Info

Publication number: WO2017007072A1
Application number: PCT/KR2015/011610
Authority: WO
Inventors: 장명식; 이준우; 장현진; 김세웅; 이길수
Original assignee: (주)오로스 테크놀로지
Priority date: 2015-07-07
Filing date: 2015-11-02
Publication date: 2017-01-12
Also published as: JP2017021317A; JP6014845B1; KR101564312B1

Abstract

The present invention relates to an overlay mark, an overlay measurement method using the same, and a method for manufacturing a semiconductor device. The present invention provides an overlay mark, which determines the relative stagger of two patterns formed on two successive pattern layers or separately formed on one pattern layer, the overlay mark comprising: a first overlay structure in the shape of a square; and a second overlay structure having four overlay patterns respectively placed on the upper and lower and left and right sides of the first overlay structure, each of the four overlay patterns having a plurality of bars parallel to each other. The overlay mark according to the present invention may be used as a mark for confirming whether pattern layers are accurately aligned in a semiconductor manufacturing process, and also may be used as a mark for confirming whether a plurality of patterns on one layer are accurately aligned.

Description

Overlay mark, overlay measuring method and semiconductor device manufacturing method using same

The present invention relates to an overlay mark, an overlay metrology method and a semiconductor device manufacturing method using the same.

A plurality of pattern layers are sequentially formed on the semiconductor substrate. In addition, a circuit of one layer may be divided into two patterns through double patterning. Such pattern layers or a plurality of patterns of one layer must be accurately formed at a predetermined position in order to manufacture a desired semiconductor device.

Thus, in order to confirm that the pattern layers are correctly aligned, overlay marks formed simultaneously with the pattern layers are used.

The method of measuring the overlay using the overlay mark is as follows. First, in the pattern layer formed in the previous process, for example, the etching process, one structure is formed which is part of the overlay mark simultaneously with the pattern layer formation. And in a subsequent process, such as a photolithography process, the remaining structure of the overlay mark is formed in the photoresist. The overlay measuring device obtains an image of the overlay structure of the pattern layer formed in the previous process (the image is transmitted through the photoresist layer) and the overlay structure of the photoresist layer, and measures the offset values between the centers of these images. Measure the overlay value. If the overlay value is out of tolerance, remove the photoresist layer and rework.

[Preceding technical literature]

Japanese Patent JP5180419

It is an object of the present invention to provide a new overlay mark that is formed simultaneously with the pattern layers to ensure that the pattern layers are correctly aligned in the semiconductor manufacturing process.

In order to achieve the above object, the present invention is an overlay mark for determining the relative gap between two consecutive pattern layer or two patterns formed separately in one pattern layer, the square shape, the corner portion of the square and the center of each side A mesa structure is formed in the mesa structure, and the mesa structure includes a first overlay structure connected by a plurality of trenches arranged in parallel, and four overlay patterns disposed on top, bottom, left, and right sides of the first overlay structure. Each of the bars includes a plurality of bars parallel to each other, the plurality of bars having a longer length, a narrower width, and alternately formed trench structures and mesa structures along the longitudinal direction as the plurality of bars move away from the first overlay structure. A second overlay structure, said first overlay structure and a second overlay structure Plaiting provides an overlay marks characterized in that each formation is formed on another layer or a pattern with a different pattern that is formed separately on one of the pattern layer.

In the overlay mark, it is preferable that the areas of the bars are equal to each other.

In addition, the trench structure may further include a plurality of trenches arranged in parallel, and the mesa structure may further include a plurality of mesas arranged in parallel.

In addition, for measuring the critical dimension (critical dimension), it may further include a circular structure formed inside the first overlay structure.

In addition, the second overlay structure may be an invariant for a 90 degree rotation.

In addition, an interval between the plurality of bars of the overlay patterns may be constant.

Further, among the four overlay patterns, bars of overlay patterns disposed above and below the first overlay structure and bars of overlay patterns disposed to the left and right of the first overlay structure may be orthogonal to each other.

In addition, it is preferable that the rotation center of the first overlay structure and the second overlay structure coincide.

In addition, the second overlay structure is preferably formed in the pattern layer formed by the previous process, the first overlay structure is preferably formed in the pattern layer formed by the subsequent process.

The present invention also provides a method of forming an overlay mark at the same time as forming two consecutive pattern layers or two patterns separately formed in one pattern layer, measuring overlay values using the overlay marks, And using the measured overlay values in the process control for forming two consecutive pattern layers or two patterns formed separately in one pattern layer, wherein the overlay marks are the overlay marks described above. It provides a manufacturing method.

The method may further include obtaining an image of an overlay mark formed at the same time as forming two consecutive pattern layers or two patterns formed separately on one pattern layer, and analyzing the image of the overlay mark. The mark provides an overlay measuring method, characterized in that the above-described overlay mark.

The overlay mark according to the present invention can be used as a mark to confirm that the pattern layers are correctly aligned in the semiconductor manufacturing process. It may also be used as a mark to confirm that a plurality of patterns of one layer are correctly aligned.

1 is a plan view showing an embodiment of an overlay mark according to the present invention.

FIG. 2 is an enlarged cross-sectional view of a portion of the overlay pattern shown in FIG. 1.

3 is a plan view showing another embodiment of an overlay mark according to the present invention.

4 is a plan view showing another embodiment of an overlay mark according to the present invention.

5 is a cross-sectional view of one of the bars of the second overlay structure shown in FIG.

FIG. 6 is a diagram for explaining inaccuracy of measurement due to asymmetry of a general overlay mark.

7 is a plan view showing a part of another embodiment of an overlay mark according to the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, embodiments of the present invention may be modified in many different forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. Embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art. Therefore, the shape and the like of the elements in the drawings are exaggerated to emphasize a more clear description, and the elements denoted by the same reference numerals in the drawings means the same elements.

Referring to FIG. 1, one embodiment of the overlay mark 100 according to the present invention includes a first overlay structure 110 and a second overlay structure 120. Overlay marks 100 may be formed in the scribe lanes of the wafer and provided to measure the overlay between two or more pattern layers on the wafer or between two or more patterns on a single layer.

When used for overlay measurement between different pattern layers, the first overlay structure 110 and the second overlay structure 120 are formed on different pattern layers. In addition, when the first overlay structure 110 and the second overlay structure 120 are the same layer when different patterns of the same layer, for example, two patterns formed in a double patterning process, are used for overlay measurement between them, Is formed. In this case, the first overlay structure 110 and the second overlay structure 120 are formed on the same layer through different processes. Hereinafter, for convenience, description will be made based on overlay measurement between different pattern layers.

As shown in FIG. 1, in the present embodiment, the first overlay structure 110 has a square shape. Two sides of the first overlay structure 110 facing each other are parallel to the first direction, and the other two sides are parallel to the second direction orthogonal to the first direction. The first direction and the second direction may be the X-axis direction and the Y-axis direction, respectively.

The second overlay structure 120 includes four

overlay patterns

121, 122, 123, and 124 disposed on the top, bottom, left, and right sides of the first overlay structure 110, respectively. Each of the four

overlay patterns

121, 122, 123, and 124 includes a plurality of

bars

125, 126, 127, and 128 parallel to each other. The plurality of

bars

125, 126, 127, and 128 of each of the

overlay patterns

121, 122, 123, and 124 are disposed at regular intervals. In addition, the lengths and widths of the plurality of

bars

125, 126, 127, and 128 of the

overlay patterns

121, 122, 123, and 124 are also the same.

The

bars

127 and 128 and the first overlay structure 110 of the

overlay patterns

123 and 124 disposed above and below the first overlay structure 110 among the four

overlay patterns

121, 122, 123, and 124. The

bars

125 and 126 of the

overlay patterns

121 and 122 disposed at the left and right sides of each other are perpendicular to each other. The

bars

127 and 128 of the

overlay patterns

123 and 124 disposed above and below the first overlay structure 110 are elongated in the X-axis direction, are disposed along the Y-axis direction, and the first overlay structure. The

bars

125 and 126 of the

overlay patterns

121 and 122 disposed at the left and right sides of the 110 extend in the Y-axis direction and are disposed along the X-axis direction. The left and

right overlay patterns

121 and 122 may be used to measure the overlay in the X-axis direction, and the top and

bottom overlay patterns

123 and 124 may be used to measure the overlay in the Y-axis direction.

Since both of the first overlay structure 110 and the second overlay structure 120 are invariants for rotation of 90 degrees, the rotation center C of the first overlay structure 110 and the second overlay structure 120 coincide with each other. , The overlay mark 100 of the present embodiment is invariant for 90 degree rotation in its entirety.

The second overlay structure 120 may be formed on the pattern layer formed in the previous process, and the first overlay structure 110 may be formed on the pattern layer formed in the subsequent process. Since the pattern layer formed in the previous process is covered by the pattern layer formed in the subsequent process, accurate image acquisition is difficult compared to the pattern layer formed in the subsequent process. Therefore, it is advantageous to form the second overlay structure 120 in a previous process, which is easier to measure more accurately.

FIG. 2 is an enlarged cross-sectional view of a portion of the overlay pattern shown in FIG. 1. As shown in FIG. 2, the plurality of

bars

125, 126, 127, and 128 of the

overlay patterns

121, 122, 123, and 124 preferably have a plurality of fine bars 130, respectively. Having an overlay mark 100 with a gap and width similar to the gap and width defined in the design rules applied to the die area of the wafer helps to reduce the error between the overlay of the actual die area and the overlay measured through the overlay mark. Because. The plurality of minute bars 130 may be formed at the same interval.

The embodiment shown in FIG. 3 is different from the embodiment shown in FIG. 1 in the second overlay structure 220, and thus only a description thereof will be provided. 3 is different from the embodiment shown in FIG. 1, the second overlay structure 220 is variable for 90 degree rotation. Moreover, it is a variable body about 180 degree rotation. In the present embodiment, the

overlay patterns

221, 222, 223, and 224 of the second overlay structure 220 are

bars

225, 226, and 227 of the

overlay patterns

221, 222, 223, and 224 facing each other. And 228 are configured to be orthogonal to each other.

Hereinafter, an overlay measurement method using the overlay mark 100 illustrated in FIG. 1 will be described. The overlay metrology method includes acquiring an image of the overlay mark 100 and analyzing the image of the overlay mark 100. The overlay mark 100 is formed at the same time as forming two consecutive pattern layers or two patterns formed separately in one pattern layer.

Acquiring an image of the overlay mark 100 may include acquiring an image of the first overlay structure 110, acquiring an image of the second overlay structure 120, and acquiring a combined image of these images. It may include a step.

When the first overlay structure 110 and the second overlay structure 120 are formed on different layers, images may be obtained using different light sources. Since the second overlay structure 120 formed in the previous process is covered by the pattern layer formed in the subsequent process, it is preferable to obtain an image using light having a wavelength that can pass through the pattern layer formed in the subsequent process.

Analyzing the image of the overlay mark 100 may be measuring the offset of the center of the first overlay structure 110 and the center of the second overlay structure 120 in the obtained combined image. In addition, measuring the distance between the center of the second overlay structure 120 and the lines corresponding to the inner edge of the first overlay structure 110 may be measured.

Hereinafter, a method of manufacturing a semiconductor device using the overlay mark 100 illustrated in FIG. 1 will be described. The method of manufacturing a semiconductor device using the overlay mark 100 begins with forming the overlay mark 100. The overlay mark 100 is formed at the same time as forming two consecutive pattern layers or two patterns separately formed in one pattern layer.

Next, the overlay value is measured using the overlay mark 100. Measuring the overlay value is the same as the overlay measurement method described above.

Finally, the measured overlay values are used for process control to form two consecutive pattern layers or two patterns formed separately in one pattern layer. That is, the derived overlay is used for process control so that a continuous pattern layer or two patterns are formed at a predetermined position.

4 is a plan view showing another embodiment of an overlay mark according to the present invention, Figure 5 is a cross-sectional view of one bar of the second overlay structure shown in FIG.

Referring to FIG. 4, the embodiment includes a first overlay structure 310, a second overlay structure 320, and a circular structure 330. The circular structure 330 is formed inside the first overlay structure 310. Circular structure 330 enables approximate critical dimension measurement based on the optical image. This can ensure process stability in the semiconductor manufacturing process. In addition, when the pattern recognition is performed through the first overlay structure 310, the circular structure 330 may make target centering, which is a process for measuring an overlay, by creating a more unique environment. It can also play a role.

As shown in FIG. 4, in the present embodiment, the first overlay structure 310 has a square shape. The second overlay structure 320 includes four

overlay patterns

321, 322, 323, and 324 disposed on the top, bottom, left, and right sides of the first overlay structure 310, respectively. Each of the four

overlay patterns

321, 322, 323, and 324 includes a plurality of bars 325, 326, 327, and 328 parallel to each other. The plurality of bars 325, 326, 327, and 328 of the

respective overlay patterns

321, 322, 323, and 324 are disposed at regular intervals.

A feature of this embodiment, which is different from the embodiment shown in FIG. 1, is that the lengths and widths of the plurality of

bars

325a, 325b, 325c, 325d, and 325e constituting one overlay pattern (eg, 321) are different from each other. The plurality of

bars

325a, 325b, 325c, 325d, and 325e have lengths that are farther from the first overlay structure 310 such that the areas of the

bars

325a, 325b, 325c, 325d, and 325e are equal to each other. It gets longer and its width narrows. That is, the innermost bar 325a has the shortest length, the widest width, and the outermost bar 325e has the longest length and the narrowest width.

According to this embodiment, even if defocus occurs, it is easy to secure precision compared to the case of having a single width bar. In addition, since it is possible to obtain more light intensity information in the area closer to the optical center than in the case of having a bar having a single width, it is combined with the mesa and trench shapes below to ensure accuracy. It has the advantage of being easy.

Another characteristic of the present embodiment, which is different from the embodiment shown in FIG. 1, is that the sides of the first overlay structure 310 and the bars 325, 326, 327, 328 of the second overlay structure 320 are formed in a mesa (along the longitudinal direction). Mesa, M) and trench (T, T) structure is formed alternately. The darker portions in Fig. 4 are concave portions. In the embodiment shown in FIG. 4, regions are allocated to mesa-trench-mesa-trench-mesa by 1/5, but the regions may be divided differently as necessary.

The application of such a structure has the advantage of reducing the error caused by the process asymmetry in the overlay mark fabrication.

As shown in FIG. 6, when fabricating an overlay structure through a semiconductor process, angles α and β of both inclined surfaces of the structure may be different from each other. Such asymmetry may occur in semiconductor processes such as chemical mechanical polishing (CMP), chemical vapor deposition (CVD), and reactive-ion etching (RIE). In the case of fabricating both overlay structures of the same layer with trench structures or mesa structures, the asymmetry in making the overlay marks may cause the overlay measurement values to be measured differently according to the focal height and the wavelength band of light used for the measurement. have.

However, as shown in FIGS. 4 and 5, when using an overlay structure in which a trench structure and a mesa structure are alternately formed on the same layer, an error in the trench structure and an error in the mesa structure partially offset each other, resulting in inaccuracy of the measurement. The advantage is that it can be minimized. That is, when the structure is formed by the semiconductor process, the asymmetry is different depending on whether the structure is a mesa structure or a trench structure, so that the error may be partially offset. In addition, by measuring the magnitude of the error, it is possible to increase the accuracy of the overlay measurement. For example, measuring the inaccuracy of the overlay structure by calculating the difference between the center point of the pair of trench structures disposed at the same distance from the center of the overlay mark and the center point of the pair of mesa structures arranged at the same distance from the center. This can increase the accuracy of the overlay measurement. In addition, by measuring the error in the trench structure and the error in the mesa structure, it is possible to increase the accuracy of the overlay measurement by using the measured value of the structure having a small error.

7 is a plan view of another embodiment of an overlay mark in accordance with the present invention. Unlike the embodiment shown in FIG. 5, the present embodiment is arranged with two or more trenches and / or mesas arranged side by side alternately along the length direction. Only the trench structure may be formed of two or more trenches parallel to each other, or only the mesa structure may be formed of two or more mesas parallel to each other, and both the trench structure and the mesa structure may be formed of two or more parallel to each other. The structure of this embodiment has the advantage that the signal strength can be improved.

The embodiments described above are merely to describe the preferred embodiments of the present invention, the scope of the present invention is not limited to the described embodiments, it is within the technical spirit and claims of the present invention Various modifications, variations, or substitutions will be made by those skilled in the art, and such embodiments should be understood to be within the scope of the present invention.

[Description of the code]

100, 200, 300, 400: Overlay Mark

110, 310, 410: first overlay structure

120, 220, 320, 420: second overlay structure

121, 122, 123, 124: Overlay Pattern

125, 126, 127, 128: bar

130: fine bar

221, 222, 223, 224: overlay pattern

225, 226, 227, 228: bar

321, 322, 323, 324: overlay pattern

Claims

An overlay mark 400 that determines the relative staggering between two consecutive pattern layers or two patterns formed separately in one pattern layer,

Mesa structure (M) is formed in the square corner portion and the center of each side of the square, the mesa structure (M) is a first overlay structure 410 connected by a plurality of trenches arranged in parallel,

Four overlay patterns 421, 422, 423, and 424 are disposed on the top, bottom, left, and right sides of the first overlay structure 410, and each of the four overlay patterns 421, 422, 423, and 424, respectively. The plurality of bars 425, 426, 427, and 428 parallel to each other are provided, and the plurality of bars 425, 426, 427, and 428 are longer and wider as they move away from the first overlay structure 410. It is narrowed, and includes a second overlay structure 420 having a trench structure (T) and mesa structure (M) formed alternately along the longitudinal direction,

The first overlay structure (410) and the second overlay structure (420) is an overlay mark, characterized in that formed on different pattern layers or with different patterns formed separately on one pattern layer.
The method of claim 1,

Overlay mark, characterized in that the areas of each of the bars 425, 426, 427, 428 are equal to each other.
The method of claim 1,

The trench mark (T) of the plurality of bars (425, 426, 427, 428) comprises a plurality of trenches arranged in parallel.
The method of claim 1,

The mesa structure (M) of the plurality of bars (425, 426, 427, 428) comprises a plurality of mesas arranged in parallel.
The method of claim 1,

An overlay mark, characterized in that it further comprises a circular structure (430) formed inside the first overlay structure (410) for critical dimension measurement.
The method of claim 1,

The second overlay structure (420) is overlay mark, characterized in that the invariant to the 90 degree rotation.
The method of claim 1,

Overlay mark, characterized in that the spacing between the plurality of bars (425, 426, 427, 428) of the overlay patterns (421, 422, 423, 424) is constant.
The method of claim 1,

Bars 427 and 428 of the overlay patterns 423 and 424 disposed above and below the first overlay structure 410 among the four overlay patterns 421, 422, 423 and 424 and the first overlay structure. Overlay marks, characterized in that the bars (425, 426) of the overlay patterns (421, 422) disposed on the left and right of the (410) are orthogonal to each other.
The method of claim 1,

Overlay mark, characterized in that the rotation center of the first overlay structure (410) and the second overlay structure (420) coincide.
The method of claim 1,

The second overlay structure (420) is formed on the pattern layer formed by a previous process, the first overlay structure (410) is an overlay mark, characterized in that formed on the pattern layer formed by a subsequent process.
In the manufacturing method of a semiconductor device,

Forming an overlay mark 400 at the same time as forming two consecutive pattern layers or two patterns separately formed in one pattern layer,

Measuring an overlay value using the overlay mark 400;

Using the measured overlay values in process control to form two consecutive pattern layers or two patterns formed separately in one pattern layer,

The overlay mark (400) is a method for manufacturing a semiconductor device, characterized in that the overlay mark (400) according to any one of claims 1 to 10.
A method of measuring the overlay between two consecutive pattern layers or two patterns formed separately on one pattern layer,

Acquiring an image of the overlay mark 400 formed at the same time as forming two consecutive pattern layers or two patterns separately formed in one pattern layer;

Analyzing the image of the overlay mark 400,

The overlay mark (400) is an overlay measurement method, characterized in that the overlay mark (400) according to any one of claims 1 to 10.