KR20090097494A - Method for fabricating phase shift mask - Google Patents

Abstract

A method for manufacturing a phase shift mask is provided to form a phase shift layer pattern without a spot defect by removing the spot detect while etching a defect preventing layer. A phase shift layer(110), a defect preventing layer(120) and a light shielding layer are formed on a substrate(100). A resist film pattern(141) which selectively exposes the light shielding layer is formed on the light shielding layer. A light shielding layer pattern(131) is formed by etching the light shielding layer using the resist film pattern as an etching mask. The spot defect is removed by etching the defect preventing layer exposed by the light shielding layer pattern. The phase shift layer pattern is formed by etching the phase shift layer using the light shielding layer pattern as the etching mask. The light shielding layer pattern and the remaining defect preventing layer are selectively removed.

Description

Method for fabricating a phase inversion mask {Method for fabricating phase shift mask}

The present invention relates to a method of forming a semiconductor device, and more particularly to a method of manufacturing a phase inversion mask.

In order to manufacture a semiconductor device, a photomask in which a pattern is formed is used. Since the pattern formed on the photomask is transferred onto the wafer through a photolithography process, the quality of the photomask is very important. In particular, as semiconductor devices are highly integrated, criteria for defects as well as critical dimensions (CD) of a pattern formed on a photomask are becoming more stringent.

Meanwhile, in order to improve the resolution of the pattern, a halftone phase shift mask (PSM) including a phase inversion pattern such as a molybdenum silicon nitride (MoSiN) film has been proposed. In this case, a light blocking film such as a chromium film is introduced to etch the phase inversion pattern. For example, in order to manufacture a halftone phase inversion mask, after forming a phase inversion film, a light blocking film and a resist film on a transparent substrate, a lithography process is performed to form a resist film pattern for selectively exposing the light blocking film. Then, the photoresist is exposed by etching the resist film pattern as an etch mask, and after removing the resist film pattern, the phase inversion film exposed by the etch mask is etched and then the light shielding film pattern is removed.

However, a resist residue may be generated on the surface of the light blocking film during the formation of the resist film pattern or the light blocking film etching process. Such a resist residue prevents etching of the light blocking film so that a part of the light blocking film to be etched remains, and the remaining light blocking film is transferred to the phase inversion film as it is, causing spot defects. These spotty defects are transferred to subsequent wafer exposure processes, resulting in wafer failure.

The method of manufacturing a phase shift mask according to the present invention includes forming a phase shift film, a defect preventing film, and a light blocking film on a substrate; Forming a resist film pattern selectively exposing the light blocking film on the light blocking film; Forming a light blocking layer pattern to selectively expose the defect prevention layer by etching the light blocking layer using the resist layer pattern as an etching mask; Isotropically etching the defect preventing film portion exposed by the light blocking film pattern to remove spot defects accompanying the formation of the light blocking film pattern; Forming a phase shift pattern by etching the exposed phase shift layer while the defect prevention layer is removed using the light blocking layer pattern as an etch mask; And selectively removing the light blocking film pattern and the remaining defect preventing film.

The defect preventing film is preferably formed of a material film having a sufficient etching selectivity with the phase inversion film.

The removing of the spot defect may include: undercut etching a portion of the defect prevention layer exposed by the light blocking layer pattern; And removing the spot defects physically lifted off on the phase inversion film by cleaning the substrate on which the defect prevention film portion is etched.

(Example)

Referring to FIG. 1, a phase inversion film 110, a defect prevention film 120, a light blocking film 130, and a resist film 140 are formed on a transparent substrate 100 such as quartz. The phase inversion film 110 may be formed of a material capable of inverting the phase of transmitted light, for example, a molybdenum silicon nitride (MoSiN) film. The defect prevention film 110 may be formed of a material film having a sufficient etching selectivity with the phase inversion film 110. The defect prevention film 120 serves to prevent spot defects caused by the subsequent light blocking film 130 and the phase shift film 120 not being etched by the residues involved in the subsequent resist film pattern formation. The light blocking layer 130 may be formed of a material capable of blocking transmitted light, for example, a chromium (Cr) film.

 Referring to FIG. 2, a resist film pattern 141 is formed to selectively expose the light blocking film 130 by performing a lithography process. Specifically, after performing an exposure process using an electron beam to the resist film, a development process using a developer is performed on the exposed resist film. Then, a resist film irradiated or irradiated with an electron beam is selectively developed to form a resist film pattern 120 for selectively exposing the light blocking film 130.

However, a resist residue 150 may be induced on the surface of the light blocking film 130 during the resist film pattern formation process. The resist residue 150 may interfere with the etching of the light blocking film 130 so that a part of the light blocking film to be etched may remain, and the remaining light blocking film may be transferred to the phase inversion film as it is, resulting in spot defects. .

Referring to FIG. 3, a light blocking layer pattern 131 which selectively exposes a defect prevention layer is formed by etching the light blocking layer exposing the resist layer pattern 141 as an etching mask. The light blocking layer pattern 131 is used as an etch barrier layer in subsequent phase inversion layer etching. At this time, due to the resist residue, a portion of the light blocking film to be etched may remain to generate a spot defect 151. The spot defect 151 may also be transferred to a subsequent phase inversion film pattern to cause the defect.

Referring to FIG. 4, the portion of the defect preventing film 120 exposed by the light blocking film pattern 131 is etched to remove spot defects (151 of FIG. 3) accompanying the formation of the light blocking film pattern 131. Specifically, after the isotropic etching of the portion of the defect prevention film 120 exposed by the light blocking film pattern 131, for example, undercut etching, the cleaning process is performed on the transparent substrate 100 on which the defect prevention film 120 is etched. Perform. Then, as the defect prevention film portion under the spot defect is etched, the spot defect is physically lifted off and removed together with the foreign matter by the cleaning process. As the defect prevention film 120 is etched, the spot defects are removed together, thereby preventing the spot defects from being transferred to the subsequent phase inversion film as it is.

Referring to FIG. 5, after removing the resist film pattern by stripping, the phase shift film exposing the light blocking film pattern 131 as an etch mask is etched to form the phase shift film pattern 111. In this case, since the spot defects that may be induced while etching the defect prevention layer are removed together, only the phase inversion layer pattern 111 may be formed without spot defects.

Referring to FIG. 6, the light blocking film pattern and the remaining defect preventing film are selectively removed. Then, a phase inversion mask for inverting the phase of light selectively transmitted by the phase inversion pattern 111 formed on the transparent substrate 100 is formed. According to the present invention, by forming a defect preventing film at the interface between the phase inversion film and the light blocking film, spot defects caused by the resist residue can be removed together while etching the defect preventing film. As a result, the transfer of spot defects to the phase inversion film can be prevented, and defect inspection and correction processes can be omitted. Embodiments of the present invention may also be applied to a binary mask in which the light blocking layer pattern is formed.

As mentioned above, although the preferred embodiment of the present invention has been described in detail, the present invention is not limited to the above embodiment, and various modifications may be made by those skilled in the art within the technical spirit of the present invention. .

1 to 6 are cross-sectional views illustrating a method of manufacturing a phase shift mask according to the present invention.

Claims (3)

Forming a phase inversion film, a defect prevention film and a light blocking film on the substrate; Forming a resist film pattern selectively exposing the light blocking film on the light blocking film; Forming a light blocking layer pattern to selectively expose the defect prevention layer by etching the light blocking layer using the resist layer pattern as an etching mask; Etching a portion of the defect preventing film exposed by the light blocking film pattern to remove spot defects accompanying the formation of the light blocking film pattern together; Forming a phase shift pattern by etching the exposed phase shift layer while the defect prevention layer is removed using the light shield layer pattern as an etch mask; And And selectively removing the light blocking film pattern and the remaining defect preventing film. The method of claim 1, And the defect preventing film is formed of a material film having a sufficient etching selectivity with the phase inversion film. The method of claim 1, Removing the spot defects, Undercut etching the defect prevention film portion exposed by the light blocking film pattern; And And removing the spot defects physically lifted off on the phase shift film by cleaning the substrate on which the defect prevention film portion is etched.

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