JPH11340122A - Identification mark - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an identification mark which is high in contrast and greatly improves pattern recognition precision. SOLUTION: An identification mark 11 which is optically recognized comprises correction of subdivided pattern elements 12, and the light projected on the surface of the identification mark 11 is irregularly reflected to raise contrast which means brightness difference against a semiconductor substrate surface. Thus, the identification mark 11 of high contrast is provided while pattern recognition precision of the identification mark 11 is greatly improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an identification mark used in a manufacturing process of a semiconductor device or a liquid crystal display panel, and more particularly, to a high contrast when optically recognized by a scanning laser microscope or the like. It relates to an identification mark that can be obtained.

[0002]

2. Description of the Related Art In a semiconductor device manufacturing process, for example, an identification mark is formed on a semiconductor substrate (semiconductor wafer) by a lithography process, and the identification mark is recognized using a scanning laser microscope. The position of a resist pattern formed on a semiconductor substrate in a lithography process is measured or aligned with reference to the recognized identification mark. Conventionally, in a manufacturing process of such a semiconductor device, an identification mark 51 formed on a semiconductor substrate by a lithography process is used.
Is, for example, as shown in FIG.
μm, and has an L shape with a line thickness of 50 μm. Further, the identification mark 51 is formed by forming a pattern corresponding to the mark 51 by a resist film in a lithography process, and then etching the pattern to form the identification mark 5.
1 is formed.

[0003]

In a semiconductor substrate having the above-described identification marks formed thereon, the identification marks on the semiconductor substrate are recognized by a scanning laser microscope or the like as shown in FIG. When the incident light 61 such as a laser is irradiated on the semiconductor substrate 62 on which the identification mark 51 is formed, the light irradiated on the surface of the identification mark 51 and the surface of the semiconductor substrate 62 is reflected light 63 as shown by an arrow. Is reflected by Then, the light applied to the edge portion of the identification mark 51 is diffused as scattered light as indicated by an arrow 64. As a result, the reflected light intensities on the surface of the identification mark 51 and the surface of the semiconductor substrate 62 become the curve 65 in FIG.
It becomes as shown in.

As is apparent from FIG. 6B, there is almost no level difference between the reflected light intensity of the mark area other than the edge portion of the identification mark 51 and the reflected light intensity of the semiconductor substrate 62. Therefore, the contrast between the mark area and the semiconductor substrate area obtained by the image processing, that is, the contrast is low. As a result, the identification mark 51 cannot be recognized unless there is a contour drawn with a high contrast at the edge portion of the identification mark 51. By the way, when an attempt is made to recognize the identification mark 51 by image processing using an outline drawn with a high contrast of an edge portion, an outline in a micron unit may be processed as a noise component. There is a problem that recognition of the identification mark 51 becomes inaccurate, and accurate measurement and alignment cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and has as its object to provide an identification mark which can obtain a high contrast and greatly improve the pattern recognition accuracy.

[0006]

According to the present invention, there is provided an identification mark formed on a surface of an article, which is optically recognized, and includes a set of subdivided pattern elements. It is characterized by comprising.

According to the present invention, since the identification mark is constituted by a set of subdivided pattern elements, the light applied to the surface of the identification mark for pattern recognition is irregularly reflected by the pattern element. You. As a result, a large difference occurs in the reflection intensity between the surface of the identification mark and the surface of the article, and the contrast, which is the difference in brightness between the surface of the identification mark and the surface of the article, can be increased. Therefore, the recognition accuracy of the identification mark can be significantly improved.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the identification mark according to the present invention will be described below with reference to the drawings.
FIG. 1 is an enlarged plan view showing a first embodiment of the identification mark of the present invention, and FIG. 2 is a diagram showing the states of reflected light and scattered light and the reflected light intensity of the identification mark and the semiconductor substrate in the first embodiment. It is explanatory drawing which shows the relationship.

In FIG. 1, reference numeral 1 denotes an identification mark forming area on a semiconductor substrate (semiconductor wafer). In the identification mark forming area 1, an identification mark 11 is formed. The identification mark 11 has a vertical and horizontal dimension of 101.
It is formed in an inverted L shape with a line thickness of 50 μm. The identification mark 11 has a planar shape of 2 μm.
It is constituted by a set in which pattern elements 12 subdivided in a convex shape with a square of m are two-dimensionally arranged at a predetermined interval (for example, 1 μm). Note that the identification mark 11 is
The resist element is formed when a resist pattern other than a mark is formed on a semiconductor substrate in a lithography process. By etching the resist film, a pattern element 12 shown in FIG.
Form a set of

[0010] The identification mark 11 constructed as described above.
In order to recognize the identification mark 11 on the semiconductor substrate with a scanning laser microscope or the like, as shown in FIG. 2A, incident light such as a laser beam is applied to the surface of the identification mark 11 and the surface of the semiconductor substrate 21. When the light 22 is irradiated, the light irradiated on the surface of the semiconductor substrate 21 is specularly reflected as shown by an arrow 23. On the other hand, the light applied to the surface of the identification mark 11 is irregularly reflected as indicated by an arrow 24. As a result, the reflected light intensity on the surface of the identification mark 11 and the surface of the semiconductor substrate 21 is as shown by a curve 25 in FIG. As is clear from FIG. 2B, the intensity of the reflected light over the entire surface area of the identification mark 11 is smaller than that of the semiconductor substrate 21.
It can be seen that the intensity of the reflected light is significantly lower than the intensity of the reflected light. Therefore, when an image detected by a scanning laser microscope or the like is subjected to image processing, the contrast, which is the difference in brightness between the mark region and the semiconductor substrate region, can be increased.

Therefore, according to the first embodiment of the present invention, since the contrast of the identification mark 11 can be made high, the identification mark 11 on the semiconductor substrate can be recognized with high accuracy. Along with this, by making the identification mark less dependent on the process for pattern recognition as in the past, fine adjustments such as pattern change and dimming of the optical system required for automation at the production factory are unnecessary,
In addition, in the manufacturing process of the semiconductor device, it is possible to prevent the recognition rate of the identification mark from being reduced due to a change in the film thickness due to a process variation, and to improve the productivity of the semiconductor device.

Referring to FIG. 3, a second embodiment of the present invention will be described. FIG. 3 is an enlarged plan view showing a second embodiment of the identification mark of the present invention. In FIG. 3, the difference from the first embodiment is that the size of the convex pattern element 12 forming the identification mark 11 is changed. That is, in the second embodiment, the vertical and horizontal dimensions are 101 μm and the line thickness is 50 μm.
It is composed of an m-shaped L-shaped identification mark 11. And
The identification mark 11 is constituted by a set of two-dimensionally arrayed pattern elements 12 each having a square and convex shape having a plane shape of 4 μm and having a convex shape at a predetermined interval (for example, 2 μm).

According to the second embodiment, the same operation and effect as those of the first embodiment can be obtained. In the second embodiment, the contrast of the identification mark 11 is lower than that of the first embodiment because the surface area of the pattern element 12 is larger than that of the first embodiment. There is no.

A third embodiment of the present invention will be described with reference to FIG. FIG. 4 is an enlarged plan view showing a third embodiment of the identification mark of the present invention. In FIG. 4, the difference from the first embodiment is that the identification mark 11 is constituted by a linear convex element. That is, in the third embodiment, the vertical and horizontal dimensions are 101 μm, and the thickness of the line is 50 μm. And the identification mark 11 is
Subdivided linear and convex pattern elements 13 having a line width of 0.80 μm are arranged at predetermined intervals (for example, 0.80 μm).
m), is constituted by a set arranged in parallel and two-dimensionally.

According to the third embodiment, the same functions and effects as those of the first embodiment can be obtained. In the third embodiment, the contrast of the identification mark 11 composed of a set of linear and convex pattern elements 13 arranged in parallel and two-dimensionally is different from that of the identification mark shown in FIG. Is the same as

In the above embodiment, the case where the identification mark 11 according to the present invention is formed on a semiconductor substrate has been described. However, the present invention is not limited to this, and may be applied to a liquid crystal display panel and other circuit components. Can be similarly applied.

[0017]

As described above, according to the present invention, the identification mark that is optically recognized is constituted by a set of subdivided pattern elements, and the irradiation light is irregularly reflected. A contrast identification mark can be obtained, and the pattern recognition accuracy of the identification mark can be significantly improved.

[Brief description of the drawings]

FIG. 1 is an enlarged plan view showing a first embodiment of an identification mark of the present invention.

FIG. 2 is an explanatory diagram showing the relationship between the state of reflected light and scattered light of the identification mark and the semiconductor substrate and the intensity of reflected light according to the first embodiment of the present invention.

FIG. 3 is an enlarged plan view showing a second embodiment of the identification mark of the present invention.

FIG. 4 is an enlarged plan view showing a third embodiment of the identification mark of the present invention.

FIG. 5 is an enlarged plan view of a conventional identification mark.

FIG. 6 is an explanatory view showing the relationship between the state of reflected light and scattered light of a conventional identification mark and a semiconductor substrate and the intensity of reflected light.

[Explanation of symbols]

1 ... identification mark forming area, 11 ... identification mark, 1
2, 13 ... pattern element, 21 ... semiconductor substrate.

Claims (6)

[Claims] 1. An identification mark formed on the surface of an article and recognized optically, comprising an aggregate of subdivided pattern elements. 2. The identification mark according to claim 1, wherein the set of pattern elements is formed in an L shape. 3. The identification mark according to claim 1, wherein the pattern elements are formed in a polygonal shape, and the polygonal pattern elements are two-dimensionally arranged at predetermined intervals. 4. The pattern element according to claim 1, wherein the pattern elements are formed in a linear shape having a predetermined width, and the linear pattern elements are arranged in parallel and two-dimensionally at predetermined intervals. Identification mark described. 5. The identification mark according to claim 1, wherein the article is a semiconductor substrate. 6. The identification mark according to claim 1, wherein the pattern element is formed by a step having a convex or concave shape.