JPH07161627A - Formation of alignment mark - Google Patents

Abstract

PURPOSE:To provide a formation method of an alignment mark so as to simplify the process of forming the alignment mark. CONSTITUTION:An insulating thin film 11 is formed on a glass board 10 and a plurality of holes 12, which are alignment marks, are formed on the insulating thin film 11 by laser processing. Therefore, conventional processes such as resist coating, exposing and developing and the process of etching the insulating thin film 11 are eliminated, and the process of forming the alignment mark is simplified.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming an alignment mark.

[0002]

2. Description of the Related Art Conventionally, in the manufacturing process of semiconductor elements such as thin film transistors, there are a plurality of photolithography steps. In this photolithography process, the alignment of the substrate of the semiconductor element is performed each time by the alignment mark composed of a plurality of holes formed on the substrate. Such an alignment mark is shown in FIG.
It is formed as shown in FIG. That is, first, as shown in FIG. 3A, an insulating thin film 2 such as silicon oxide is formed on a substrate 1, a resist 3 is applied on the insulating thin film 2, and then a resist is formed as shown in FIG. Unnecessary portions of the resist 3 are removed by exposing and developing the surface of the resist 3, and the insulating thin film 2 is etched by using the resist 3 as a mask to remove the resist 3 from above the insulating thin film 2. As shown in FIG. As shown in FIG. 3, a plurality of hole portions 4 serving as alignment marks are formed in the insulating thin film 2. The alignment mark is formed in a small area on the end of the substrate 1.

[0003]

However, in such a conventional method of forming an alignment mark, a resist 3 is applied on the insulating thin film 2, the surface is exposed and developed, and then the resist 3 is used as a mask. Since the insulating thin film 2 must be etched, there is a problem in that the alignment mark is formed in a small area on the edge of the substrate 1 but the forming process is complicated and the manufacturing time is long. An object of the present invention is to provide a method of forming an alignment mark that can simplify the process of forming the alignment mark.

[0004]

According to the present invention, a thin film is formed on a substrate and an alignment mark is formed on the thin film by laser processing.

[0005]

According to the present invention, since the alignment mark is formed on the thin film formed on the substrate by laser processing,
Conventional processes such as resist coating, exposure, and development,
Further, the thin film etching step and the like are not required, and the alignment mark forming step can be simplified. In this case, when the thin film is formed of the insulating film and the polysilicon film and the alignment mark is formed on one of the surfaces located on the surface, for example, the polysilicon film by laser processing, the alignment mark Since the depth can be easily controlled, the boundary surface between the insulating film and the polysilicon film can be formed flat, which allows the alignment mark to be searched with a small number of times when searching the position of the alignment mark with an electron beam or the like. You can check the position of.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. 1 (a) and 1 (b). First, Fig. 1
As shown in (a), a glass substrate 10 of a semiconductor element such as a thin film transistor is placed on a table in a chamber (not shown), and an insulating thin film 11 such as silicon oxide or silicon nitride is deposited on the glass substrate 10 by CVD or sputtering. 500-5000Å, preferably 800-20
It is formed with a film thickness of about 00Å. After that, as shown in FIG. 1B, a plurality of hole portions 12 that are alignment marks are formed in the insulating thin film 11 by laser processing in which the insulating thin film 11 is directly irradiated with a laser beam. The laser used for this laser processing is a kind of solid-state laser and has a wavelength of 1.0.
It is a 6 μm YAG laser. YA of this YAG laser
G is Y ₃ Al ₅ O ₁₂ and is a host crystal for using Nd ³⁺ as the active medium of the laser. In laser processing using this YAG laser, 1
25 or more square hole portions 12 each having a side of about 10 μm are formed in parallel at intervals of about 10 μm. Further, in this laser processing, it is easy to control the depth of the hole portion 12 formed in the insulating thin film 11.

In such an alignment mark forming method, since the alignment mark is formed by the laser processing in which the insulating thin film 11 formed on the glass substrate 10 is directly irradiated with the laser beam, the conventional resist 3 is applied. The steps of exposure, development, etc. and the step of etching the insulating thin film 2 are not required, the step of forming the alignment mark can be simplified, and the productivity of the semiconductor element can be improved. In this case, the hole 12 of the alignment mark has a simple square shape and one side has one side.
Since it is a relatively large size of about 0 μm, it can be accurately formed by a YAG laser, and the alignment mark can be easily confirmed by searching with an electron beam or the like.

In the above first embodiment, the glass substrate 1
Although the insulating thin film 11 is formed on the insulating film 11 and the alignment mark is formed on the insulating thin film 11 by laser processing, the invention is not limited to this. For example, a polysilicon film is formed on the glass substrate 10 and laser processing is performed on the polysilicon film. The alignment mark may be formed by.

Next, a second embodiment of the present invention will be described with reference to FIGS. 2 (a) and 2 (b). The same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. First, as shown in FIG. 2A, an insulating film 20 such as silicon oxide or silicon nitride is CVed on the glass substrate 10.
A polysilicon film 21 is formed on the insulating film 20 with a film thickness of about 500 to 1000Å by D or sputtering.
It is formed by VD to a film thickness of about 2000 to 5000 Å. After that, as shown in FIG. 2B, a plurality of hole portions 12 as alignment marks are formed in the polysilicon film 21 by the same laser processing as in the first embodiment. In this laser processing, since it is easy to control the depth of the hole 12 formed in the polysilicon film 21, the polysilicon film 2
1 and the insulating film 20 can be formed to have a flat interface.

In such an alignment mark forming method, the alignment mark is formed by laser processing on the polysilicon film 21 formed on the glass substrate 10 with the insulating film 20 interposed therebetween. Therefore, the same effect as the first embodiment is obtained. In addition, in particular, in the conventional etching process, it is difficult to control the boundary surface between the polysilicon film 21 and the insulating film 20 and unevenness occurs on the boundary surface, whereas in the laser processing, the boundary surface is formed flat. Therefore, when inspecting the alignment mark with an electron beam or the like, the position of the alignment mark can be confirmed with a small number of searches, and the search time can be shortened.

In the second embodiment, the glass substrate 1
The insulating film 20 is formed on the insulating film 20, the polysilicon film 21 is formed on the insulating film 20, and the alignment mark is formed on the polysilicon film 21 by laser processing. However, the invention is not limited to this. A polysilicon film is formed on the substrate, an insulating film is formed on the polysilicon film,
An alignment mark may be formed on this insulating film by laser processing.

[0012]

As described above, according to the present invention, since the alignment mark is formed on the thin film formed on the substrate by the laser processing, the conventional steps such as resist coating, exposure and development, Further, the thin film etching step and the like are not required, and the alignment mark forming step can be simplified.

[Brief description of drawings]

1A and 1B show a first embodiment of a method for forming an alignment mark according to the present invention, wherein FIG. 1A is a sectional view of an essential part of a state where an insulating thin film is formed on a glass substrate, and FIG. 1B is a laser treatment of the insulating thin film. FIG. 4 is a cross-sectional view of a main part in a state where an alignment mark is formed by.

2A and 2B show a second embodiment of the method of forming an alignment mark of the present invention, FIG. 2A is a cross-sectional view of a main part in a state where a polysilicon film is formed on a glass substrate with an insulating film interposed therebetween, FIG.
FIG. 3 is a cross-sectional view of an essential part of a state where an alignment mark is formed on the polysilicon film by laser processing.

FIG. 3 shows a conventional method of forming an alignment mark,
(A) shows that an insulating thin film is formed on a glass substrate,
A cross-sectional view of an essential part in a state where a resist is applied on the insulating thin film, (b) is a cross-sectional view of an essential part in a state where the resist is exposed and developed, and (c) is an etching of the insulating thin film using the resist as a mask. After forming the alignment mark,
Sectional drawing of the principal part in the state which peeled the resist.

[Explanation of symbols]

 10 Glass Substrate 11 Insulating Thin Film 12 Hole 20 Insulating Film 21 Polysilicon Film

Claims (4)

[Claims] 1. A method of forming an alignment mark, which comprises forming a thin film on a substrate and forming an alignment mark on the thin film by laser processing. 2. The method of forming an alignment mark according to claim 1, wherein the thin film is an insulating film and is formed by CVD or sputtering. 3. The thin film is a polysilicon film, and CV
The alignment mark forming method according to claim 1, wherein the alignment mark is formed by D. 4. The method of forming an alignment mark according to claim 1, wherein the thin film is composed of an insulating film and a polysilicon film, and the alignment mark is formed on one of the surfaces located on the surface.