KR20090100619A - Method for fabricating of choromeless phase shift mask - Google Patents

Abstract

PURPOSE: A method for fabricating of choromeless phase shift mask is provided to shorten TAT(Turn Around Time) by line width control. CONSTITUTION: The buffer layer and light shield layer are formed on the substrate(100). The resist film pattern which selectively exposes the light shield layer on the light shield layer is formed. The light block film pattern(122a) is formed by etching the light shield layer using the resist film pattern as the etching mask. The light block film pattern is over-etched using the sidewall profile of the light block film pattern. The buffer film pattern(111) is formed by etching the buffer layer. The resist film pattern is removed. The phase inversion pattern(130) is formed. The buffer film pattern and light block film pattern are selectively removed.

Description

Method for fabricating of choromeless phase shift mask

The present invention relates to a method of manufacturing a photomask, and more particularly to a method of manufacturing a chromeless phase inversion mask.

A photomask in which a pattern is formed is used as a method for implementing a pattern to be formed on a wafer in the process of manufacturing a semiconductor device. Since the pattern embodied on the photomask is transferred onto the wafer through a photolithography process, the manufacturing process of the photomask is very important. However, as the integration degree of the device increases, it becomes difficult to accurately implement the pattern to be formed on the wafer as the pattern size becomes finer.

Therefore, a phase shift mask (PSM) has been proposed that implements a 0 ° phase region and a 180 ° phase region on a mask to utilize diffraction and interference effects, in particular, a trench for inverting the phase of light transmitted through the substrate. Research has been conducted on chromeless phase shift masks in which a pattern is formed to form a pattern only by phase difference of light.

The chromium-less phase inversion mask first forms a light blocking film and a resist film on a transparent substrate such as quartz, and then performs a photolithography process to form a resist pattern exposing a 180 ° phase region, and the resist pattern is exposed to an etch mask. The blocking layer pattern is etched to form a light blocking layer pattern. Subsequently, after the resist pattern is removed, a portion of the light blocking layer pattern exposed by the etching mask is etched to form a trench for inverting the phase of light in the substrate. The chromeless phase inversion mask transfers the pattern onto the wafer by using a phase difference between the trench pattern formed in the substrate and the substrate.

However, as the design rule of the device is reduced, a footing phenomenon in which the line width of the upper portion of the pattern becomes larger than the line width of the lower portion of the resist film pattern due to insufficient etching margin in the photolithography process including the exposure process and the developing process. Is generated. The effect of this putting phenomenon affects the mask pattern profile during subsequent etching. For example, a slope is also induced on the sidewalls of the light blocking layer pattern, and thus, the trench sidewalls formed in the substrate have a slope profile as the exposure width narrows toward the bottom surface.

Since the light blocking layer pattern serves as an etching mask for etching the trench, an etch target for the light blocking layer pattern should be increased to form a light blocking layer pattern having a vertical profile. In this case, as the etching time is increased by increasing the etching target, the line width CD value of the light blocking layer pattern is changed or a pattern line width deviation occurs. In addition, the portion of the substrate exposed during the etching process may be damaged by the etching plasma to change the subsequent phase difference, thereby affecting the mask manufacturing process.

Method for producing a chromeless phase inversion mask according to the present invention, forming a buffer 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; Etching the light blocking film exposing the resist film pattern with an etching mask to form a light blocking film pattern; Over-etching the light blocking layer pattern such that a sidewall profile of the light blocking layer pattern is vertical; Etching the buffer film exposing the resist layer pattern and the light blocking layer pattern as an etching mask to form a buffer layer pattern; Removing the resist film pattern; Forming a phase inversion pattern that inverts the phase of transmitted light by etching the portion of the substrate exposed by the light blocking layer pattern and the buffer layer pattern; And selectively removing the buffer layer pattern and the light blocking layer pattern.

The buffer film may be formed to include a nitride film, and the light blocking film may be formed to include a chromium film.

The light blocking layer pattern may be formed using a mixed gas including chlorine (Cl ₂ ) gas and oxygen (O ₂ ) gas.

The over-etching of the light blocking layer pattern may be performed while the portion of the substrate exposed between the light blocking layer patterns is protected by the buffer layer.

The buffer layer pattern may be formed using a mixed gas including methyl fluoride (CH ₂ F ₂ ) gas, carbon tetrafluoride (CF ₄ ) gas, and oxygen (O ₂ ) gas.

The removing of the buffer layer pattern and the light blocking layer pattern may include forming a resist layer pattern blocking an edge region of the substrate on the substrate and the light blocking layer pattern on which the phase shift region is formed; Etching the light blocking film pattern exposed by the resist film pattern; Preferably, the light blocking layer pattern is etched, and the exposed buffer layer pattern is etched.

Method of manufacturing a chromeless phase inversion mask according to an embodiment of the present invention, forming a buffer film, a light blocking film and a resist film pattern on a substrate; Etching the light blocking film exposed by the resist film pattern to form a light blocking film pattern; Measuring a line width of the light blocking layer pattern; Over-etching the light blocking layer pattern such that a sidewall profile of the light blocking layer pattern is vertical while reducing the line width of the light blocking layer pattern formed to a line width relatively larger than a target pattern; Etching the buffer film exposing the resist layer pattern and the light blocking layer pattern as an etching mask to form a buffer layer pattern; Removing the resist film pattern; Forming a phase inversion pattern that inverts the phase of transmitted light by etching the portion of the substrate exposed by the light blocking layer pattern and the buffer layer pattern; And selectively removing a portion of the buffer layer pattern and the light blocking layer pattern.

(Example)

Referring to FIG. 1, a hard buffer layer 110, a light blocking film 120, and a resist film 130 are formed on a transparent substrate 100 such as quartz. The buffer film 110 may be formed of a material film having an etching selectivity with the transparent substrate 100 and the light blocking film 120, for example, a nitride film, but is not limited thereto. The buffer film 110 may be formed to a thickness of 90 to 100 Å. Here, the buffer layer 110 serves to prevent the transparent substrate 100 of the 0 ° phase region from being damaged by the etching source during the over-etching process for the subsequent light blocking layer pattern. The light blocking film 120 may be formed of a material capable of blocking the transmitted light, for example, a chromium (Cr) film, but is not limited thereto.

Referring to FIG. 2, a photolithography process is performed to form a resist film pattern 131 that selectively exposes the light blocking film. Specifically, the resist film pattern 131 is transferred to the resist film by performing an exposure process using a normal electron beam, and then subjected to a developing process using a developer to selectively expose a light blocking film. In this case, the resist film pattern 131 may be disposed to expose a 180 ° phase inversion region to be subsequently formed.

The light blocking film portion exposed by the resist film pattern 131 is etched to form the light blocking film pattern 121. Specifically, a mixed gas including an etching gas such as chlorine (Cl ₂ ) gas and oxygen (O ₂ ) gas is supplied to the light blocking film exposed by the resist film pattern 131. Then, the portion of the light blocking layer exposed by the resist layer pattern 131 is etched by the etching gas, thereby forming the light blocking layer pattern 121 that selectively exposes the buffer layer 110.

However, in the photolithography process, the developing solution and the polymer react to cause a footing phenomenon in which the line width of the upper portion of the pattern becomes larger than the CD (Critical dimension) of the lower portion of the resist pattern 131. As a result, a slope is caused on the sidewalls of the light blocking layer pattern, and thus a difference in exposure line width between the upper end and the lower end of the light blocking layer pattern 121 is generated.

Referring to FIG. 3, the etching target for the light blocking layer pattern having the inclined profile is increased to overetch. Then, the light blocking film pattern is over-etched by a mixed gas including an etching source, for example, chlorine gas and oxygen gas, thereby forming a light blocking film pattern 122 having a vertical profile in which the sidewalls are vertical. In this case, the buffer layer 110 serves to prevent the portion of the transparent substrate 100 in the 0 ° phase region from being attacked by the etching plasma.

Meanwhile, before performing the over etching, the line width of the light blocking layer pattern may be measured to determine whether to perform the CD correction process. For example, when the line width of the light blocking layer pattern is measured to have a line width relatively larger than the line width to be formed, the CD layer may be formed to have a desired target line width by performing the CD correction process on the light blocking layer while performing over etching. It may be.

Referring to FIG. 4, after the resist layer pattern is removed using a strip process, the buffer layer pattern 111 is formed by etching the light-blocking layer pattern 122 having a vertical sidewall profile 122 as an etch mask. do. Specifically, methyl fluoride (CH ₂ F ₂ ) gas, carbon tetrafluoride (CF ₄ ) gas, and oxygen (O ₂ ) gas are supplied to the transparent substrate 100 on which the buffer film is exposed by the light blocking layer pattern 122. do. As a result, the buffer layer pattern 111 that selectively exposes the transparent substrate portion is formed by etching the buffer layer portion exposed by the light blocking layer pattern. Here, the buffer layer pattern 111 serves as a mask in the process of etching the transparent substrate to form a subsequent 180 ° phase inversion pattern.

Referring to FIG. 5, a phase inversion pattern which may invert a phase of light in the transparent substrate 100 by etching a portion of the transparent substrate 100 where the light blocking layer pattern 122a and the buffer layer pattern 111 are exposed as an etch mask. 130 is formed. In this case, the phase inversion pattern 130 may be formed using an etching source used for etching the buffer layer, for example, methyl fluoride gas, carbon tetrafluoride gas, and oxygen gas. Also. Etching for forming the buffer layer pattern and the trench may be sequentially performed in the same chamber.

Meanwhile, in the process of forming the phase reversal pattern 130 in the substrate, a portion of the light blocking film pattern 122a is lost by the etching plasma, so that the light blocking film pattern 122a is reduced to generate a line width difference with the target pattern. At this time, even if the light blocking film pattern 122a is lost due to the etching plasma and the light blocking film pattern 122a and the CD d1 are changed, the CD (d2) of the underlying buffer film pattern 111 is not affected by the etching plasma. The CD of the target line width is maintained. Accordingly, the phase inversion pattern 130 formed in the transparent substrate may have a vertical profile and may be formed to a target line width to be formed.

Referring to FIG. 6, after the light blocking layer pattern (122a of FIG. 5) is removed from the main region, the exposed buffer layer pattern 111 is removed using an etch back process. Then, a phase inversion pattern 130 capable of inverting the phase of light by 180 ° is formed in the substrate to form a chromeless phase inversion mask having a phase difference.

According to the present invention, a buffer layer is deposited during the manufacture of a chromeless phase reversal mask, and the light blocking layer pattern is over-etched to form a light blocking layer pattern having a vertical sidewall profile, and then the over-etched light blocking layer pattern is used as an etching mask. To form. A portion of the transparent substrate exposed by the light blocking layer pattern and the buffer layer pattern as an etch mask is etched to form a trench pattern having a phase difference in the main pattern region. Accordingly, by increasing the etch target amount of the light blocking layer pattern, it is possible to control the footing phenomenon caused by insufficient etching margin, and to prevent the transparent substrate portion exposed by the buffer layer from being over-etched. In addition, even when the light blocking layer pattern is damaged during the trench etching and the pattern line width is changed, the pattern line width to be formed during the trench etching may be maintained by the buffer layer pattern. Therefore, in manufacturing the chromeless phase reversal mask, it is possible to control the line width error and the pattern profile to suppress the line width defects and to reduce the cost of manufacturing and purchasing the raw materials. In addition, by reducing the mask manufacturing time through the line width control can reduce the TAT (Turn Around Time), it is possible to increase the etching margin.

As mentioned above, 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. Of course.

1 to 6 are views showing for explaining a method of manufacturing a chromeless phase inversion mask according to the present invention.

Claims (12)

Forming a buffer 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; Etching the light blocking film exposing the resist film pattern with an etching mask to form a light blocking film pattern; Over-etching the light blocking layer pattern such that a sidewall profile of the light blocking layer pattern is vertical; Etching the buffer film exposing the resist layer pattern and the light blocking layer pattern as an etching mask to form a buffer layer pattern; Removing the resist film pattern; Forming a phase inversion pattern that inverts the phase of transmitted light by etching the portion of the substrate exposed by the light blocking layer pattern and the buffer layer pattern; And And selectively removing the buffer layer pattern and the light blocking layer pattern. The method of claim 1, The buffer film is formed including a nitride film, the light blocking film is a chromium-less phase inversion mask manufacturing method comprising a chromium film. The method of claim 1, The light blocking layer pattern is formed using a mixed gas containing chlorine (Cl ₂ ) gas and oxygen (O ₂ ) gas. The method of claim 1, The over-etching of the light blocking layer pattern may be performed while a portion of the substrate exposed between the light blocking layer patterns is protected by the buffer layer. The method of claim 1, The buffer layer pattern is a method of manufacturing a chromeless phase inversion mask formed using a mixed gas containing methyl fluoride (CH ₂ F ₂ ) gas, carbon tetrafluoride (CF ₄ ) gas and oxygen (O ₂ ) gas. The method of claim 1, Selectively removing the buffer layer pattern and the light blocking layer pattern, Forming a resist film pattern blocking an edge region of the substrate on the substrate and the light blocking film pattern on which the phase inversion region is formed; Etching the light blocking film pattern exposed by the resist film pattern; And etching the exposed buffer layer pattern while the light blocking layer pattern is etched. Forming a buffer 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; Etching the light blocking film exposed by the resist film pattern to form a light blocking film pattern; Measuring a line width of the light blocking layer pattern; Over-etching the light blocking layer pattern such that a sidewall profile of the light blocking layer pattern is vertical while reducing the line width of the light blocking layer pattern formed to a line width relatively larger than a target pattern; Etching the buffer film exposing the resist layer pattern and the light blocking layer pattern as an etching mask to form a buffer layer pattern; Removing the resist film pattern; Forming a phase inversion pattern that inverts the phase of transmitted light by etching the portion of the substrate exposed by the light blocking layer pattern and the buffer layer pattern; And And selectively removing a portion of the buffer layer pattern and the light blocking layer pattern. The method of claim 7, wherein The buffer film is formed by including a nitride film, the light blocking film is a method of manufacturing a chromeless phase inversion mask formed by including a chromium film. The method of claim 7, wherein The light blocking layer pattern is formed using a mixed gas containing chlorine (Cl ₂ ) gas and oxygen (O ₂ ) gas. The method of claim 7, wherein The over-etching of the light blocking layer pattern may be performed while a portion of the substrate exposed between the light blocking layer patterns is protected by the buffer layer. The method of claim 7, wherein The buffer film pattern is a method of manufacturing a chromeless phase inversion mask formed using a mixed gas containing methyl fluoride (CH ₂ F ₂ ) gas, carbon tetrafluoride (CF ₄ ) gas and oxygen (O ₂ ) gas. The method of claim 7, wherein Selectively removing the buffer layer pattern and the light blocking layer pattern, Forming a resist layer pattern on the substrate and the light blocking layer pattern on which the phase inversion region is formed to block edge regions of the substrate; Etching the light blocking film pattern exposed by the resist film pattern; And etching the exposed buffer layer pattern while the light blocking layer pattern is etched.

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