JPH11265528A - Production of stamper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a having surface smoothness of a high degree by subjecting a silicon substrate 1 formed with rugged patterns to a heat treatment of a prescribed temp., thereby smoothing its surface. SOLUTION: The surface roughness of the rugged patterns is increased by unequal etching and the formation of a natural oxidized film 11 on the silicon substrate 1 surface, etc., during an etching stage of forming the desired rugged patterns on the silicon substrate 1 surface. Namely, silicon terminals are bonded to OH groups on the silicon substrate 1 surface formed with the oxidized film 11. When the substrate is heat treated for 5 to 60 minutes at 600 to 900 deg.C in a hydrogen atmosphere, the OH groups are substituted with the hydrogen. The hydrogen is smaller in atomic size than the OH groups and is easily dulled by heat and, therefore, the surface roughness may be decreased. Then, the surface of the rugged patterns of the silicon substrate 1 may be smoothed. As a result, the high-reliability stamper having the improved surface smoothness is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a stamper, and more particularly, to a method of manufacturing a stamper which is used as a master when manufacturing an optical disk or the like and has a highly accurate uneven pattern.

[0002]

2. Description of the Related Art Conventionally, for example, when an optical disk or the like is formed, a desired uneven pattern is formed on a plastic substrate constituting the optical disk.
Generally, the formation of the concavo-convex pattern of the optical disc is performed by transferring the concavo-convex pattern to the plastic substrate by injection molding using a stamper having a concavo-convex pattern corresponding to the concavo-convex pattern as a master. ing.

The rugged pattern of the optical disc requires high dimensional accuracy as the capacity of the optical disc is increased. To improve the dimensional precision of the rugged pattern, a stamper, which is a master (master) of the optical disc, is used. It is necessary to improve the dimensional accuracy of the concavo-convex pattern formed on the substrate.

As one of the methods, a stamper is manufactured by using a silicon substrate (master). This stamper is usually manufactured by the following method.

That is, a photoresist film is applied on a silicon substrate, and the photoresist film is selectively exposed and developed to form a desired resist pattern. Next, after the silicon substrate is etched using the resist pattern as a mask, the resist pattern is removed to obtain a stamper on which a desired uneven pattern is formed.

[0006]

However, in the stamper made of the silicon substrate, unevenness occurs when etching is performed on the silicon substrate using the resist pattern as a mask in the manufacturing process, and the oxidization formed on the surface of the silicon substrate. The film (SiO ₂ film) has a defect that its surface is roughened and the roughness of the silicon substrate surface is increased. For this reason, it is difficult to obtain a stamper having surface activity. The increase in surface roughness causes noise when recording and reproducing signals on an optical disk, and thus hinders accurate recording and reproduction of signals.

SUMMARY OF THE INVENTION An object of the present invention is to solve such a conventional problem. By smoothing the surface of a concavo-convex pattern formed on a stamper, a stamper having a high surface smoothness can be obtained. It is an object of the present invention to provide a stamper manufacturing method capable of obtaining a stamper.

[0008]

According to the present invention, there is provided a first step of selectively etching a silicon substrate to form a desired concavo-convex pattern on a surface of the silicon substrate. Heat treatment is performed on the silicon substrate on which is formed at a predetermined temperature to smooth the surface.
And a method of manufacturing a stamper comprising the steps of:

According to this method, even if the surface roughness of the silicon substrate increases in the first step, the surface becomes dull and smooth by the heat treatment.

The heat treatment performed in the second step can be performed in a hydrogen atmosphere. Further, the heat treatment performed in the second step can be performed at a temperature of 600 ° C to 900 ° C.

After the second step, a third step of performing a heat treatment on the silicon substrate in an atmosphere containing at least oxygen to form a thermal oxide film on the surface of the silicon substrate can be performed.

[0012]

Next, embodiments of the present invention will be described with reference to the drawings.

1 and 2 are process sectional views showing a method of manufacturing a stamper according to the present embodiment, and FIGS. 3 and 4 are enlarged sectional views showing a part of the method of manufacturing a stamper according to the present embodiment. FIG.

In the step shown in FIG. 1A, a photoresist film 2 is formed on a silicon substrate 1 to a thickness of about 0.1 μm. In this embodiment mode, a positive photoresist is used.

Next, in the step shown in FIG.
The photoresist film 2 obtained in the step (1) is exposed according to the pattern to be formed on the stamper. The exposure was performed using, for example, a Kr laser having a wavelength of 351 nm. Next, the exposed photoresist film 2 is developed to form a resist pattern 3 on the silicon substrate 1.

Next, in the step shown in FIG.
Using the resist pattern 3 obtained in the step (2) as a mask, the silicon substrate 1 is etched using, for example, Cl ₂ as an etching gas under the conditions of a flow rate of 50 sccm, a pressure of 1 Pa, and a bias between electrodes of 100 w. A desired concavo-convex pattern is formed on the surface of the substrate 1. Here, in this etching step, unevenness in etching occurs or an oxide film (Si
O ₂ ) is formed and the roughness of the surface of the uneven pattern is increased.

Next, in the step shown in FIG.
The resist pattern 3 is removed from the silicon substrate 1 obtained in the step shown in (3). Next, the silicon substrate 1
Then, heat treatment is performed in a hydrogen atmosphere at a temperature of 600 ° C. to 900 ° C. for 5 to 60 minutes. By doing so, the surface of the concavo-convex pattern formed on the silicon substrate 1 is smoothed. The reason why this surface is smoothed is as follows.

That is, a natural oxide film 11 is formed on the surface of the silicon substrate 1 before this heat treatment step, as shown in FIG. Here, looking at the surface of the silicon substrate 1 at the atomic level, the terminal of the silicon atom is linked to the hydroxyl group (-OH) on the surface of the silicon substrate 1. When the silicon substrate 1 in this state is subjected to the heat treatment under the above-described conditions, the hydroxyl group (-OH) at the terminal of silicon is replaced with hydrogen (-H). Here, hydrogen has a smaller atomic size than (-H) and a hydroxyl group (-OH), and is easily blunted by heat, so that surface roughness can be reduced. Therefore, as shown in FIG. 3B, the surface of the concavo-convex pattern on the silicon substrate 1 can be smoothed.

Although it is more effective to perform this heat treatment in a hydrogen atmosphere for the smoothing, it is not always necessary to perform the heat treatment in a hydrogen atmosphere. That is, by performing a heat treatment at a predetermined temperature on the silicon substrate on which the desired concavo-convex pattern is formed, the surface is dulled, so that the surface of the concavo-convex pattern on the silicon substrate 1 can be smoothed.

Although the surface of the concavo-convex pattern on the silicon substrate 1 can be smoothed by the above-described steps, a step described below is further added after these steps, whereby the surface of the concavo-convex pattern on the silicon substrate 1 is further added. Can be further achieved.

Specifically, when the silicon substrate 1 is left as it is after the step shown in FIG. 4A, a natural oxide film grows on the surface. Thereafter, the silicon substrate 1 is subjected to a cleaning process. At this time, a natural oxide film grown on the surface of the silicon substrate 1 is removed. Since the natural oxide film grows unevenly on the silicon substrate 1, if the natural oxide film is removed by the cleaning process, the surface roughness of the silicon substrate 1 may be slightly increased. Therefore, by further performing the steps described below,
The smoothing can be further improved.

That is, after the step shown in FIG. 1D is completed, hydrogen is replaced with an inert gas such as argon to eliminate the hydrogen atmosphere. After that, the process proceeds to the step shown in FIG. 2A.
Heat treatment for ~ 60 minutes. By doing so, the surface of the concavo-convex pattern formed on the silicon substrate
Thermal oxide film 5 is formed to a thickness of about {1000}. FIG. 4A shows a partially enlarged view of this state.

The oxide film formed by the above steps is
It is formed to a uniform thickness compared to the native oxide film.
In the cleaning step shown in (2), even if the oxide film is removed, it is possible to prevent an increase in surface roughness as shown in FIG. 4 (2).

In the process described in the present embodiment, various conditions such as temperature, time, and film thickness of the film to be formed are not limited to these conditions. This is achieved by performing a heat treatment at least at a predetermined temperature on the silicon substrate 1 on which the above-described uneven pattern is formed.

[0025]

As described above, according to the stamper manufacturing method of the present invention, a heat treatment is performed at a predetermined temperature on a silicon substrate on which a desired concavo-convex pattern to be formed on the stamper is formed. The surface of the silicon substrate can be smoothed. As a result, a highly reliable stamper with improved surface smoothness can be manufactured.

Further, after the heat treatment is completed, the silicon substrate is heat-treated in an atmosphere containing at least oxygen to form a thermal oxide film on the surface of the silicon substrate, thereby further improving the effect. Can be.

[Brief description of the drawings]

FIG. 1 is a process sectional view illustrating a method for manufacturing a stamper according to an embodiment of the present invention.

FIG. 2 is a process cross-sectional view illustrating a method of manufacturing a stamper according to an embodiment of the present invention.

FIG. 3 is an enlarged sectional view showing a part of a method of manufacturing a stamper according to an embodiment of the present invention.

FIG. 4 is an enlarged cross-sectional view showing a part of the method of manufacturing a stamper according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Silicon substrate 2 Photoresist 3 Resist pattern 5 Thermal oxide film 11 Natural oxide film

Claims (4)

[Claims] 1. A method for selectively etching a silicon substrate,
A stamper comprising: a first step of forming a desired concavo-convex pattern on the surface of the silicon substrate; and a second step of heat-treating the silicon substrate on which the concavo-convex pattern is formed at a predetermined temperature to smooth the surface. Manufacturing method. 2. The method according to claim 1, wherein the heat treatment performed in the second step is performed in a hydrogen atmosphere. 3. The heat treatment performed in the second step is performed at 600 ° C.
The method for producing a stamper according to claim 1, wherein the method is performed at a temperature of about 800 ° C. 4. After the second step, a third step of performing a heat treatment on the silicon substrate in an atmosphere containing at least oxygen to form a thermal oxide film on a surface of the silicon substrate is performed. Item 4. The method for manufacturing a stamper according to any one of Items 3.