KR101095675B1 - Method for correcting crtical demension in photomask - Google Patents

Abstract

After the phase inversion film and the light blocking film are formed on the substrate, the light blocking film is patterned to form a light blocking film pattern for selectively exposing the phase inversion film. A self-assembled film is formed on the light-blocking film pattern to selectively react with the light-blocking film pattern, and the light-blocking film pattern is further etched using the self-assembled film to correct the line width of the light-blocking film pattern. The present invention provides a method for correcting a line width of a photomask, in which a phase inversion layer pattern is formed by etching a light blocking layer pattern having a line width corrected and a phase inversion layer exposed by an etching mask of a self-assembled layer formed on the light blocking layer.

Self-assembled film, line width, correction process, phase inversion mask, light blocking film

Description

Method for correcting crtical demension in photomask

The present invention relates to a method for manufacturing a photomask, and more particularly to a method for correcting a line width of a photomask.

During the process of manufacturing a semiconductor device, a photomask in which a pattern is formed is used as a method for implementing a pattern to be formed on a semiconductor substrate. Since the pattern formed on the photomask is transferred onto the wafer through a photolithography process, the critical dimension (CD) of the pattern implemented on the photomask is very important.

As the degree of integration of semiconductor devices increases, the sizes of the patterns constituting the semiconductor devices also become smaller. Accordingly, patterns having a smaller line width are also formed on the patterns formed on the photomask, and it is difficult to accurately implement design rules required by current mass production processes. In addition, it is difficult to implement a pattern having a desired CD on the photomask due to various causes in the photomask manufacturing process.

Accordingly, a method of correcting CD MTT (Mean To Target) of a pattern is used to have a CD of a desired target pattern during a photomask manufacturing process.

In the CD correction process of the phase inversion mask, first, a resist film pattern is formed on a transparent substrate on which the phase inversion film and the light blocking film are formed through a photolithography process, and then the light blocking film is exposed by etching the resist film pattern as an etching mask. A light blocking film pattern is formed. The CD of the light shielding pattern is measured through a measuring device and the CD of the light shielding pattern is corrected by additionally etching the light shielding pattern. The phase shift layer is exposed by etching the corrected light blocking layer pattern as an etch mask to form a phase shift layer pattern.

Meanwhile, the light blocking layer pattern remains in the frame region of the phase shift mask to block light in a subsequent wafer exposure process. However, during the additional etching process for correcting the CD of the light blocking film pattern, the light blocking film pattern formed in the frame region of the phase shift mask is affected. For example, the light blocking layer pattern formed in the frame region is damaged, and the reflection of light in the frame region is severe during subsequent wafer exposure, resulting in process loss.

Accordingly, after forming a separate mask pattern which blocks the frame region of the phase shift mask and exposes the main pattern region where the phase shift mask pattern is disposed, a CD correction process and a method of etching the phase shift mask pattern have been proposed. .

However, as the separate mask pattern performs a resist coating, an exposure process, and a developing process, process time and manufacturing cost increase. In addition, resist defects may be caused by using the resist as a mask pattern. For example, a resist defect may remain on the surface of the phase inversion film due to the foreign matter caused during the exposure process and the development process. Accordingly, in the etching process for etching the phase shift layer, a resist defect acts as an etch mask for the phase shift layer, thereby causing the phase shift layer not to be etched or a defective pattern in which the phase shift layer patterns are bridged. Can be.

In accordance with another aspect of the present invention, there is provided a method of correcting a line width of a photomask, the method including: forming a phase inversion film and a light blocking film on a substrate; Patterning the light blocking film to form a light blocking film pattern for selectively exposing the phase shift film; Forming a self-assembled film selectively reacting with the light blocking film pattern on the light blocking film pattern; Correcting the line width of the light blocking layer pattern by additionally etching the light blocking layer pattern using the self-assembled film; Forming a phase shift layer pattern by etching the phase shield layer having the line width corrected and the self-assembled layer formed on the light shield layer as an etch mask; And removing the self-assembled film.

The phase inversion film is preferably formed of a molybdenum silicon nitride film, and the light blocking film is formed of a chromium film.

Forming the self-assembled film, it is preferable to form by a vapor deposition method or a liquid phase deposition method.

The forming of the self-assembled film may include forming a silane-based material that selectively reacts with the light blocking film pattern using a material; And removing the silane-based material physically adsorbed on the surface of the phase shift film exposed by the light blocking film pattern.

The physically adsorbed silane-based material may be removed by performing a rinse process using an ethanol solution.

In the removing of the self-assembled film, the self-assembled film remaining on the upper surface of the light blocking film pattern whose line width is corrected may be removed by irradiating ultraviolet rays.

(Example)

Referring to FIG. 1, a phase inversion film 110 and a light blocking film 120 are formed on a transparent substrate 100 such as a quartz substrate. 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 light blocking layer 120 may be formed of a material capable of blocking transmitted light, for example, a chromium (Cr) film.

Although not shown in detail, the transparent substrate 100 may include a main pattern region in which a phase inversion film pattern is formed to invert a phase of transmitted light, and a light blocking film in order to indicate an alignment sensor and a barcode reader of a scanner. It is divided into frame areas.

A resist film pattern 130 for selectively exposing the light blocking film 120 is formed on the light blocking film 120.

Specifically, after the resist film is formed on the transparent substrate 100 on which the phase inversion film 110 and the light blocking film 120 are formed, the resist film is formed on the resist film by performing an exposure process using a conventional electron beam (e-beam). Transfer the pattern. A developing process using a developing solution is performed to selectively develop a portion irradiated or not irradiated with an electron beam to form a resist film pattern 130 that selectively exposes the light blocking film.

Referring to FIG. 2, the light blocking film is etched in the form of a resist film pattern 130 to form a light blocking film pattern 121 that selectively exposes the phase inversion film 110. The light blocking layer pattern 121 serves as an etch barrier layer when a subsequent phase shift pattern is formed. Therefore, when the line width (CD) of the light blocking layer pattern 121 is known, the CD of the subsequent phase shift pattern may be predicted.

Referring to FIG. 3, after removing the resist film pattern, the line width (CD) of the light blocking film pattern 121 is measured through a CD measuring device.

For example, since it is difficult to form a light blocking film pattern and a phase inversion film pattern having a target pattern to be formed due to process instability and lack of process capability in a photomask manufacturing process, the CD with the target pattern through CD measurement is measured. The difference can be calculated.

Referring to FIG. 4, a self assembled monolayer 140 may be selectively formed on an upper surface of the light blocking layer pattern 121. The self-assembled film 140 may be formed using a silane-based forming material, and may be formed using a long carbon chain material among silane-based materials, for example, an OTS (Octadecyl Trichloro Silane) material. . In this case, the self-assembled film 140 may be deposited in a vapor phase by reacting with the light blocking film pattern 121 in a low vacuum state, or by reacting with the light blocking film pattern 121 in a liquid phase. In addition, the self-assembled film 140 may be formed using an adhesion plate included in the resist coating track equipment.

For example, the light blocking layer pattern 121 is exposed to the atmosphere to include the OH group. Due to these characteristics, the silane-based forming material does not react with the phase inversion film 110 exposed by the light blocking film pattern 121, but reacts with the light blocking film pattern 121 to form an upper surface of the light blocking film pattern 121. The self-assembled film 140 is formed. At this time, the silane-based forming material 141 physically adsorbed remains on the surface of the phase inversion layer exposed by the light blocking layer pattern.

Referring to FIG. 5, a rinse process is performed to remove silane-based forming material (141 of FIG. 4) that is physically adsorbed on the phase inversion film pattern. Then, the self-assembly film 140 is selectively left only on the upper surface of the light blocking film pattern. At this time, the rinsing process may be performed using an ethanol solution. The self-assembled film 140, which remains selectively only on the upper surface of the light blocking film pattern 121, may be used as a correction mask for correcting the light blocking film pattern 121 in a subsequent CD correction process.

Referring to FIG. 5, the CD MTT of the light blocking layer pattern 121a is corrected to have a CD of the target pattern to be formed by further etching the light blocking layer pattern using the self-assembled film 140.

The CD correction process uses the self-assembled film 140 reacted with the upper surface of the light shielding film pattern as a correction mask, and measures the CD of the light shielding film pattern 121a by the CD difference ΔCD with the target pattern to be formed. Correct.

During the CD correction process, the light blocking layer pattern 121a disposed in the frame region may be protected by the self-assembly layer 140. Therefore, it is possible to prevent the light blocking layer pattern 121a disposed in the frame region from being damaged by the additional etching of the light blocking layer pattern 121a.

In addition, since the CD of the phase inversion film pattern subsequently formed by the corrected light blocking film pattern 121a is determined, the CD of the light blocking film pattern 121a is corrected before etching the phase inversion film. CD MTT accuracy can be improved.

Referring to FIG. 6, a phase inversion layer pattern 111 is formed by etching the phase inversion layer exposed by the corrected light blocking layer pattern 121a as an etch mask. Since the phase shift film pattern 111 forms the light blocking film pattern 121a corrected by the CD correction process using an etching mask, the phase shift film pattern 111 having the same CD as the target pattern to be formed may be formed. Can be.

Referring to FIG. 7, the self-assembled film remaining on the upper surface of the light blocking film pattern 121a whose line width is corrected is removed. The self-assembled film may be removed by irradiating ultraviolet light while suppressing damage of the light blocking film pattern 121a.

 Subsequently, the light blocking film pattern formed in the main pattern region is selectively removed. Then, the phase inversion film pattern 111 is disposed in the main pattern area to invert the phase of the transmitted light, and the phase inversion film pattern 111 and the light blocking film pattern 121a are arranged in the frame area to block the transmitted light. Can be.

According to the present invention, a self-assembled film is formed using a silane-based material that selectively reacts with the light blocking film without a separate mask pattern addition process. Accordingly, a correction mask for correcting the CD of the light blocking layer pattern and a protective film capable of protecting the light blocking layer pattern disposed in the frame area during CD correction may be implemented. Accordingly, the TAT time can be shortened due to the simplification of the process, and various unit processes such as resist coating, exposure process, and development process can be omitted to suppress foreign matter generation and prevent resist defects, thereby improving the quality of the photomask. The yield of the device can be increased.

Although the present invention has been described in detail with reference to preferred embodiments, the present invention is not limited to the above embodiments, and various modifications may be made by those skilled in the art within the technical spirit of the present invention. Do.

1 to 7 are diagrams for explaining the line width correction method of the photomask according to the present invention.

Claims (6)

Forming a phase inversion film and a light blocking film on the substrate; Patterning the light blocking film to form a light blocking film pattern for selectively exposing the phase shift film; Forming a self-assembled film selectively reacting with the light blocking film pattern on the light blocking film pattern; Correcting the line width of the light blocking layer pattern by additionally etching the light blocking layer pattern using the self-assembled film; Forming a phase shift layer pattern by etching the phase shield layer having the line width corrected and the self-assembled layer formed on the light shield layer as an etch mask; And And removing the self-assembled film. Claim 2 has been abandoned due to the setting registration fee. The method of claim 1, And the phase inversion film is formed of a molybdenum silicon nitride film, and the light blocking film is formed of a chromium film. Claim 3 was abandoned when the setup registration fee was paid. The method of claim 1, The forming of the self-assembled film may include forming a photomask using a vapor deposition method or a liquid deposition method. Claim 4 was abandoned when the registration fee was paid. The method of claim 1, Forming the self-assembled film, Forming a silane series using a material to selectively react with the light blocking layer pattern; And Removing the silane-based material physically adsorbed on the surface of the phase shift film exposed by the light blocking film pattern. Claim 5 was abandoned upon payment of a set-up fee. 5. The method of claim 4, Removing the physically adsorbed silane-based material is a line width correction method of removing the photomask by performing a rinse process using an ethanol solution. Claim 6 was abandoned when the registration fee was paid. The method of claim 1, The removing of the self-assembled film may include removing the self-assembled film by irradiating ultraviolet rays to the self-assembled film remaining on the upper surface of the light-blocking film pattern with the corrected line width.

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