JP2745988B2 - Photomask manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photomask manufacturing method for forming a dielectric pattern on a glass substrate without using an etching stopper film.

[0002]

2. Description of the Related Art FIG. 3 is a schematic sectional view showing a conventional process for manufacturing a phase shift type photomask. First, FIG.
As shown in FIG. 1A, an etching stopper film 2 is formed on a transparent substrate 1 made of, for example, glass, and a dielectric film 3a is formed on the upper surface thereof by, for example, SOG coating or SiO ₂ sputtering. Next, a resist film for electron beam lithography (hereinafter referred to as EB)
As a resist film 4a, for example, a positive resist is applied. Then, the electron beam 5 is irradiated to other portions of the EB resist film 4a except for a portion corresponding to a desired dielectric pattern 3 described later.

Next, as shown in FIG. 3B, the EB resist film 4a is developed and etched to form a resist pattern 4. Then, as shown in FIG. 3C, the transparent substrate 1 is subjected to an illegal reactive ion etching (hereinafter referred to as RIE) process using the resist pattern 4 as a mask.
The underlying dielectric film 3a is selectively etched away, and RIE is performed when the etching stopper film 2 is exposed.
To end. Finally, when the transparent substrate 1 is ashed to remove the resist pattern 4, a desired dielectric pattern 3 is formed on the transparent substrate via the etching stopper film 2 as shown in FIG. A phase shift photomask is obtained.

[0004]

The conventional phase shift type photomask is formed by the above-described manufacturing method, and the etching stopper film 2 is interposed between the dielectric pattern 3 and the transparent substrate 1. When pattern transfer is performed on a Si wafer or the like using ultraviolet light through this phase shift photomask, the ultraviolet light transmittance of the etching stopper film 2 is low, so that an image is blurred and a highly accurate pattern transfer cannot be obtained. There was a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a method of manufacturing a photomask capable of transferring a pattern with high accuracy by eliminating the need for an etching stopper film. It is the purpose.

[0006]

A method of manufacturing a photomask according to the present invention comprises the steps of sequentially forming a metal film having a thickness equal to a desired dielectric pattern and a resist film for electron beam writing on a transparent substrate. Forming a resist pattern by removing a portion corresponding to a desired dielectric pattern of the electron beam writing resist film, and removing a metal pattern by removing an exposed portion of the metal film using the resist pattern as a mask. Forming, sequentially forming a dielectric film and a resist film on the transparent substrate and the metal pattern, removing the dielectric film and the resist film until the upper surface of the metal pattern is exposed, and removing the metal pattern And forming a desired dielectric pattern.

[0007]

The method of manufacturing a photomask according to the present invention comprises:
A metal pattern having the same thickness as the desired dielectric pattern is formed, and the upper surface of the metal pattern functions as an etching stopper to enable high-precision pattern transfer, and an electron beam is formed by forming a metal film on the base. The EB resist film is prevented from being charged at the time of drawing.

[0008]

【Example】

Embodiment 1 FIG. Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing a manufacturing process of a phase shift photomask according to Embodiment 1 of the present invention. First,
As shown in FIG. 1A, for example, a transparent substrate 1 such as glass
1, a metal film 12a made of, for example, Al, Cr, or the like having a thickness equal to the thickness of a desired dielectric pattern 15 described later.
To form Then, an EB resist film 13a such as a positive resist is formed on the upper surface, and an electron beam 14 is applied to a portion of the EB resist film 13a corresponding to a desired dielectric pattern 15.

Next, as shown in FIG. 1B, the EB resist film 13a is developed and etched to form a resist pattern 13. Then, as shown in FIG. 1C, using the resist pattern 13 as a mask, the metal film is subjected to RIE processing to form a metal pattern 12, and as shown in FIG. 1D, a dielectric film 15a is The metal pattern 12 is formed thicker than the metal pattern 12 by SOG coating or SiO ₂ sputtering, and a resist film 16 having the same etching rate as that of the dielectric film 15a is coated thereon to increase the flatness. Next, as shown in FIG. 1E, the dielectric film 15a and the resist film 16 are removed by etching until the metal pattern 12 is exposed. Finally, as shown in FIG. By removing the metal pattern 12, a dielectric pattern 15 is formed on the transparent substrate, and a phase shift photomask is obtained.

The phase shift type photomask obtained by the manufacturing method according to the first embodiment of the present invention has a dielectric pattern 15 directly on the transparent substrate 11 without an etching stopper film unlike the conventional one. Is formed, the transmittance of ultraviolet rays is improved, and a pattern transfer with high accuracy is obtained. In addition, at the time of electron beam drawing, since the metal film 12a is interposed in the base, the EB resist may be charged. Is prevented.

Embodiment 2 FIG. FIG. 2 is a schematic cross-sectional view showing a manufacturing process of a phase shift photomask in Embodiment 2 of the present invention. In the above embodiment, a method of manufacturing a phase shift photomask having only the dielectric pattern 15 has been described. However, the present invention is applied to a method of manufacturing a phase shift photomask having a dielectric pattern and a metal pattern on the same substrate. It is also possible.

Hereinafter, a method of manufacturing a phase shift type photomask according to a second embodiment of the present invention will be described with reference to FIG. First, as in the case of the first embodiment, FIGS.
The manufacturing process up to FIG. Next, an EB resist film 17a such as a positive resist is formed on the upper surfaces of the metal pattern 12 and the dielectric pattern 15 as shown in FIG. The electron beam 14 is irradiated. Next, as shown in FIG. 2B, the EB resist film 17a is developed and etched to form a resist pattern 17, and using this resist pattern 17 as a mask, as shown in FIG. 12 is selectively removed by wet etching. Finally, when the resist pattern 17 is removed by ashing, a phase shift photomask having the metal pattern 12 and the dielectric pattern 15 on the transparent substrate 11 is obtained as shown in FIG.

[0013]

As described above, according to the present invention, a step of sequentially forming a metal film having a thickness equal to a desired dielectric pattern and a resist film for electron beam drawing on a transparent substrate, Removing the portion of the resist film corresponding to the desired dielectric pattern to form a resist pattern, and forming a metal pattern by removing the exposed portion of the metal film using the resist pattern as a mask, Forming a dielectric film and a resist film sequentially on the transparent substrate and the metal pattern; removing the dielectric film and the resist film until the upper surface of the metal pattern is exposed; removing the metal pattern to obtain a desired dielectric film; Providing a method of manufacturing a photomask capable of transferring a pattern with high accuracy by eliminating the need for an etching stopper film by including a step of forming a body pattern. It can be.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a step of manufacturing a phase shift mask type photomask in Embodiment 1 of the present invention.

FIG. 2 is a schematic cross-sectional view showing a step of manufacturing a phase shift photomask in Embodiment 2 of the present invention.

FIG. 3 is a schematic cross-sectional view showing a manufacturing process of a conventional phase shift photomask.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 11 Transparent substrate 2 Etching stopper 3, 15 Dielectric pattern 3a, 15a Dielectric film 4, 13, 17 Resist pattern 4a, 13a, 17a EB resist film 5, 14 Electron beam 12 Metal pattern 12a Metal film 16 Resist film

Claims (1)

(57) [Claims] A step of sequentially forming a metal film having a thickness equal to a desired dielectric pattern and a resist film for electron beam drawing on a transparent substrate, and forming the desired dielectric pattern on the resist film for electron beam drawing on the transparent substrate. Removing a corresponding portion to form a resist pattern; forming a metal pattern by removing an exposed portion of the metal film using the resist pattern as a mask; and forming a metal pattern on the transparent substrate and the metal pattern. Forming a dielectric film and a resist film in sequence, removing the dielectric film and the resist film until the upper surface of the metal pattern is exposed, and removing the metal pattern to form a desired dielectric pattern. Forming a photomask.