KR20210015157A - Blankmask and photomask for the Flat Panel Display - Google Patents

Abstract

The present invention provides a blank mask for a flat panel display having a multilayer film of two or more layers on a transparent mask substrate and configured to have a higher etch rate with respect to the same etching material than films provided thereon so that a cross-sectional shape has a reverse inclination when forming a pattern through etching with the lowermost layer in contact with a transparent substrate. Accordingly, the present invention can suppress the tail of a pattern after etching, thereby increasing the resolution of the pattern, and transfer of the fine pattern is possible.

Description

Blankmask and photomask for the Flat Panel Display}

The present invention relates to a blank mask and a photomask for a flat panel display, and more particularly, a blank mask for a flat panel display capable of increasing the resolution of a light-shielding pattern and capable of transferring a fine pattern, and a photo produced using the same. It's about the mask.

Today, FPD (Flat Panel Display) products such as LCD (Liquid Crystal Display) and OLED (Organic Light Emitting Diode) have expanded their application range as the market demands have become more advanced, highly functional, and diversified. Development of this excellent manufacturing process technology is required.

In general, FPD devices are manufactured by forming a _photomask using a _{blank mask} on which at least one metal film is deposited, and applying it to a photolithography process, and the FPD blank mask and photomask are simply exposed to light. A binary form that implements only two transmittance steps of transmission and blocking is mainly used.

In manufacturing a device for FPD, in order to increase the accuracy of the CD (Critical Dimension) of the transfer pattern, the cross-sectional inclination of the light shielding film pattern and the antireflection film pattern provided in the photomask should be formed to be steep. Such a pattern having a steep cross-sectional shape can improve CD precision of a transfer pattern by minimizing interference of exposure light during an exposure process.

1 is a cross-sectional view showing a conventional photomask for FPD.

Referring to FIG. 1, in the conventional binary photomask, after forming a blank mask for FPD including a light blocking film, an antireflection film, and a resist film on a transparent substrate 102, the resist film is patterned using a photolithography process, and The film pattern 110 is manufactured by wet etching the light-shielding film and the anti-reflective film using an etching mask to form the light-shielding film pattern 104 and the anti-reflection film pattern 106.

However, as shown in FIG. 1, as the patterns of the FPD photomask are formed through wet etching, the light-shielding layer pattern 104 and the anti-reflection layer pattern 106 are formed with a wet etching solution from the transparent substrate 102 to the top. Due to the isotropic etching that increases the exposure time to the lower portion, as a large amount of the lower portion is etched, a tail is generated due to a gentle side slope, and the precision of the transfer pattern is deteriorated during the exposure process due to the side slope of the pattern. .

The present invention is to solve the above problems, and an object of the present invention is to provide a blank mask and a photomask for an FPD capable of increasing the resolution of a light shielding film pattern constituting a photomask and capable of transferring fine patterns.

The blank mask for a flat panel display according to the present invention is provided with two or more multilayer films on a transparent substrate, and the lowermost layer in contact with the transparent substrate is provided on the top so that the cross-sectional shape has a reverse slope when a pattern is formed through etching. It is configured to have a faster etching rate for the same etching material than the previously formed layers.

The multilayer film is formed by stacking two or more light shielding films on a transparent substrate and an antireflection film on the uppermost layer.

Among the multilayer films, the lowermost layer is an antireflection film, and at least one light shielding film and an antireflection film are stacked on the antireflection film.

Each of the multilayer films is composed of one of Cr, CrN, CrO, CrC, CrNO, CrCN, CrCO, and CrCON.

Among the multilayer films, the film in contact with the transparent substrate contains less carbon (C) than at least one of the upper films, or does not contain carbon (C).

Among the multilayer films, the lowermost layer in contact with the transparent substrate has a higher nitrogen (N) content than at least one of the upper layers.

According to the present invention, since the lowermost layer adjacent to the transparent substrate among the multilayer films of two or more layers is configured to have a faster etching rate than the upper layers, tail of the pattern after etching can be suppressed.

Accordingly, the resolution of the pattern can be increased, and the fine pattern can be transferred.

1 is a cross-sectional view showing a conventional photomask for FPD.
2 is a cross-sectional view showing a photomask for an FPD according to an embodiment of the present invention.
3 is a cross-sectional view showing a blank mask for an FPD according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail through examples of the present invention with reference to the drawings, but the examples are used only for the purpose of illustrating and explaining the present invention, and the present invention described in the claims It was not used to limit the scope of. Therefore, those of ordinary skill in the technical field of the present invention will understand that various modifications and equivalent other embodiments are possible from the embodiments. Therefore, the true technical protection scope of the present invention should be determined by the technical details of the claims.

2 is a cross-sectional view showing a photomask for an FPD according to an embodiment of the present invention, and FIG. 3 is a cross-sectional view showing a blank mask according to an embodiment of the present invention.

Referring to FIG. 2, a photomask 200 for an FPD according to the present invention includes a transparent substrate 202 and a multilayer pattern 210 of two or more layers provided on the transparent substrate 202. Here, the FPD photomask 200 includes a blank mask 300 including a multilayer film 210 and a resist film 212 of two or more layers provided on the transparent substrate 202, as shown in FIG. 3. It is formed by using.

The transparent substrate 202 is a rectangular transparent substrate having one side of 300 mm or more, and may be a synthetic quartz glass substrate, a soda lime glass substrate, an alkali-free glass substrate, a low thermal expansion glass substrate, or the like.

The multilayer pattern 210 may be composed of two or more multilayer films partitioned so that each film has a different composition or composition ratio, or may be composed of a continuous film whose composition or composition ratio is continuously changed in the vertical direction. That is, a plurality of light-shielding layers are formed by making the composition or composition ratio of the materials of the multilayer pattern 210 listed above different according to the position of the multilayer pattern 210 in the vertical direction. In the present invention, the terms "layer" and "membrane" are used to include all cases in which physical properties are changed by being divided in stages or continuously changed as described above.

Each of the films for forming the multilayer pattern 210 may be formed by various methods using a physical or chemical vapor deposition method, and is preferably formed using a DC Magnetron Reactive Sputtering device. In this case, a thin film may be formed by a single sputtering target or a co-sputtering method using a plurality of same or different sputtering targets.

The multilayer pattern 210 is formed of a stacked structure of a light blocking film and an antireflection film. For example, the multilayer pattern 210 may be formed by stacking two-layered light-shielding pattern 204 and 206 and an anti-reflective layer pattern 208 on the uppermost layer. In addition, the multilayer film pattern 210 is composed of the lowermost layer film 204 adjacent to the transparent substrate 202 as an antireflection film, and one or more light shielding films 206 on the upper surface thereof and the antireflection film 208 on the uppermost layer are stacked. Can be.

Each layer constituting the multilayer pattern 210 is chromium (Cr), aluminum (Al), cobalt (Co), tungsten (W), molybdenum (Mo), vanadium (V), palladium (Pd), titanium (Ti). ), platinum (Pt), iron (Fe), nickel (Ni), cadmium (Cd), magnesium (Mg), copper (Cu), sulfur (S), indium (In), tin (Sn), beryllium (Be ), tantalum (Ta), hafnium (Hf), and silicon (Si). In addition, in order to control optical properties such as transmittance and reflectance, and physical properties such as etch rate and durability, the multilayer pattern 210 may contain at least one of oxygen (O), nitrogen (N), and carbon (C). It may be configured to further include.

The multilayer pattern 210 is made of a material etched in the same etching solution, and is preferably made of Cr or one of CrN, CrO, CrC, CrNO, CrCN, CrCO, and CrCON.

Of the multilayer pattern 210, the lowermost layer 204 adjacent to the transparent substrate 202 has a cross-sectional shape having an inverted slope shape having an upper portion having a longer length than a lower portion. To this end, when a pattern is formed through etching, the lowermost layer 204 is configured to have a faster etching rate for the same etching material than the layers provided thereon such that the cross-sectional shape has an inverse slope. Therefore, the multilayer pattern 210 can suppress the formation of Tail.

The etching rate of the multilayer pattern 210 may be controlled by the content of at least one of oxygen (O), nitrogen (N), and carbon (C). That is, by adjusting the content of one or more of these elements, the etching rate of the multilayer pattern 210 may be slow or fast. The lowermost layer 204 of the multilayer pattern 210 has an etch rate ratio of 1.1 to 5.0 compared to at least one or more of the upper layers.

The etching rate of the multilayer pattern 210 may be preferably controlled by the content of carbon (C). The content of the carbon (C) can be controlled by forming a film by adjusting the atmosphere of the carbon (C) gas that may be included in the formation of the multilayer film. That is, when the lowermost layer 204 is formed in the multilayer deposition process, the concentration of the gas containing carbon (C) or carbon (C) is less than one or more of the upper layers, or does not contain carbon (C). By doing so, the concentration of carbon (C) can be made higher toward the top of the light-shielding film.

In addition, the etching rate of the multilayer pattern 210 may be preferably controlled by the content of nitrogen (N). That is, the layer 204 in contact with the transparent substrate among the multilayer layers is formed to have a higher nitrogen (N) content than at least one of the upper light blocking layers, thereby increasing the etching rate.

On the other hand, in the multilayer film pattern 210, when the content of oxygen (O) and nitrogen (N) increases, the transmittance of the film increases. Since the light shielding film pattern 204 must have high light shielding properties, it is not preferable that the content of oxygen (O) and nitrogen (N) is high. However, when the thickness of the light-shielding layer pattern 204 is thick, sufficient light-shielding properties can be secured even if the content of oxygen (O) and nitrogen (N) increases. Therefore, the light-shielding film patterns 204 contain oxygen (O) and nitrogen (N) to a certain extent, and the content of oxygen (O) and nitrogen (N) is adjusted to secure the light-shielding property required for the light-shielding film pattern 204 It is desirable to configure it below a certain level.

In consideration of this, when each of the films is made of a chromium (Cr) compound, 10 at% to 90 at% of chromium (Cr), 0 to 50 at% nitrogen (N), 0 to 25 at% oxygen (O), and carbon (C) It has a content of 0 to 25 at%.

The lowermost layer 204 of the multilayer pattern 210 has a horizontal distance of 50 Å to 1,000 Å between the top and bottom edges when viewed in cross section.

On the other hand, by configuring the thickness of each film constituting the multilayer pattern 210 to be 50 Å to 1,000 Å, it is possible to prevent a decrease in light blocking property due to the inclusion of nitrogen (N). The entire multilayer pattern 210 has a thickness of 500 Å to 1,600 Å, preferably 600 Å to 1,400 Å. In addition, since the multilayer pattern 210 is composed of a light-shielding film and an anti-reflection film, it has a transmittance of 0.3% to 0.001% with respect to exposure light of a complex wavelength including I, H, and G-line. It has Optical Density and has a surface reflectance of 20% or less, preferably 15% or less.

As described above, according to the present invention, the multilayer pattern 210 is formed so that the lowermost layer 204 has a reverse slope and an etching rate is faster than that of the upper layers for the same etching solution.

Accordingly, it is possible to suppress the formation of tail occurring at the interface between the transparent substrate and the multilayer pattern 210 used as a light-shielding film or anti-reflection film, thereby increasing the resolution of the pattern, and transferring a fine pattern.

(Example)

Example 1: blank mask, Photo mask Manufacturing and evaluation

A blank mask according to an embodiment of the present invention was manufactured, and a photomask was manufactured using the blank mask.

First, referring to FIGS. 2 and 3, two layers of films 204 and 206 used as light-shielding films by DC magnetron reactive sputtering equipment using a chromium (Cr) target on a transparent substrate 202 and an antireflection film thereon A film 208 used as a film was formed to form a multilayer film 210.

Here, among the films used as the light-shielding film, the lowermost layer 204 was formed by injecting at a ratio of Ar: N ₂ : CH ₄ = 30: 70: 10, and the upper layer 206 was compared to the lowermost layer 204. Thus, in order to slow the etching rate, that is, to increase the ratio of carbon (C) to relatively increase the etching rate of the lowermost layer 204, Ar: N ₂ : CH ₄ = 30: 10: 10 Was formed.

Subsequently, a resist film 214 was formed on the multilayer film 210 to complete the manufacture of the _{blank mask} according to the present invention.

Thereafter, the resist layer was patterned to form a resist layer pattern, and an etching process was performed on the lower multilayer layer 210 using the mask and evaluated.

At this time, it was confirmed that the lowermost layer 204 has an etching rate of 35 Å/sec, and the upper layer 206 has an etching rate of 25 Å/sec, so that the etching rate of the lowermost layer 204 having a relatively decreased carbon (C) ratio is high. .

In addition, as a result of measuring the cross section of the multilayer pattern 210 using an electron scanning microscope after etching, the etching speed of the lowermost layer 204 in contact with the transparent substrate 202 is faster than that of the upper layers 206 and 208. It was confirmed that no putting phenomenon was observed.

Example 2 : Blank mask , Photo mask Manufacturing and evaluation

2 and 3, a DC magnetron reactive sputtering device using a chromium (Cr) target on a transparent substrate 202 is used as a light-shielding film with two layers of films 204 and 206 used as an anti-reflection film thereon. The resulting film 208 was formed to form a multilayer film 210.

Here, among the films used as the light-shielding film, the lowermost layer 204 was formed by injecting at a ratio of Ar: N ₂ : CH ₄ = 30: 70: 5, and the upper layer 206 compared to the lowermost layer 204 Therefore, in order to slow the etching rate, that is, to increase the ratio of carbon (C) to relatively speed up the etching rate of the lowermost layer 204, Ar: N ₂ : CH ₄ = 30: 70: 10 Was formed.

Subsequently, a resist film 214 was formed on the multilayer film 210 to complete the manufacture of the _{blank mask} according to the present invention.

Thereafter, the resist layer was patterned to form a resist layer pattern, and an etching process was performed on the lower multilayer layer 210 using the mask and evaluated.

At this time, it was confirmed that the lowermost layer 204 has an etching rate of 50 Å/sec, and the upper layer 206 has an etching rate of 30 Å/sec, so that the etching rate of the lowermost layer 204 having a relatively reduced carbon (C) ratio is high. .

In addition, as a result of measuring the cross section of the multilayer pattern 210 using an electron scanning microscope after etching, the etching speed of the lowermost layer 204 in contact with the transparent substrate 202 is faster than that of the upper layers 206 and 208. It was confirmed that no putting phenomenon was observed.

Comparative example

A single-layer light-shielding film having the same etching rate in the film and an antireflection film was formed on the transparent substrate by a DC magnetron reactive sputtering equipment using a chromium (Cr) target.

Here, the light-shielding film is Ar: was formed by injection at a ratio of _{5: N 2: CH 4 =} 30: 70.

Then, a resist film was formed on the multilayer film to complete the manufacture of the _{blank mask} according to the present invention.

Thereafter, the resist layer was patterned to form a resist layer pattern, and an etching process was performed on the lower antireflection layer and the light shielding layer using the mask and evaluated.

At this time, the light-shielding film exhibited an etch rate of 30 Å/sec, and as a result of measuring a cross section of the light-shielding film pattern using an electron scanning microscope after etching, it was confirmed that a putting phenomenon was observed in the light-shielding film portion in contact with the transparent substrate.

Above, the present invention is specifically described through the embodiments of the present invention with reference to the drawings, but the examples are used only for the purpose of illustrating and explaining the present invention, and the meaning of the present invention described in the claims or It is not used to limit the scope. Therefore, those of ordinary skill in the art will appreciate that various modifications and equivalent other embodiments are possible from the embodiments. Therefore, the true technical protection scope of the present invention should be determined by the technical matters of the claims.

202: transparent substrate 204: lowermost layer film
206: upper membrane 208: uppermost membrane
210: multilayer film 212: resist film

Claims (11)

Two or more multilayer films are provided on the transparent substrate,
A blank mask for a flat panel display, wherein the lowermost layer in contact with the transparent substrate is configured to have a higher etch rate with respect to the same etching material than the layers provided thereon so that the cross-sectional shape has an inverse slope when a pattern is formed through etching.
The method of claim 1,
The multi-layered film is a blank mask for a flat panel display, characterized in that formed by stacking two or more light-shielding films on a transparent substrate and an antireflection film on an uppermost layer.
The method of claim 1,
A blank mask for a flat panel display, characterized in that the lowermost layer of the multilayer films is an antireflection film, and at least one light shielding film and an antireflection film are stacked on the uppermost layer on the antireflection film.
The method according to claim 1 or 2,
The multilayer film is chromium (Cr), aluminum (Al), cobalt (Co), tungsten (W), molybdenum (Mo), vanadium (V), palladium (Pd), titanium (Ti), platinum (Pt), Iron (Fe), nickel (Ni), cadmium (Cd), magnesium (Mg), copper (Cu), sulfur (S), indium (In), tin (Sn), beryllium (Be), tantalum (Ta), Consisting of any one or more of hafnium (Hf) and silicon (Si), or further comprising any one or more of oxygen (O), nitrogen (N), and carbon (C) in the material Blank mask for flat panel displays.
The method of claim 1,
The multilayer film is a blank mask for a flat panel display, characterized in that consisting of one of Cr, CrN, CrO, CrC, CrNO, CrCN, CrCO, CrCON, respectively.
The method of claim 1,
The multilayer film contains a chromium (Cr) compound, and contains chromium (Cr) 10 at% to 90 at%, nitrogen (N) 0 to 50 at%, oxygen (O) 0 to 25 at%, and carbon (C) 0 to 25 at% A blank mask for a flat panel display, characterized in that it has a.
The method of claim 1,
A blank mask for a flat panel display, wherein a film of the multilayer film in contact with the transparent substrate contains less carbon (C) than at least one of the upper films or does not contain carbon (C).
The method of claim 1,
A blank mask for a flat panel display, wherein a lowermost layer of the multilayer film in contact with the transparent substrate has a higher nitrogen (N) content than at least one of the upper layers.
The method of claim 1,
Each film constituting the multilayer film has a thickness of 50 Å to 1000 Å. A blank mask for a flat panel display.
A photomask for a flat panel display manufactured using a blank mask for a flat panel display,
It includes a multilayer pattern of two or more layers provided on a transparent substrate,
A photomask for a flat panel display in which a cross-sectional shape of at least one of the multilayer patterns in contact with the transparent substrate has an inverted slope.
The method of claim 10,
A photomask for a flat panel display, wherein a horizontal distance between an uppermost and a lowermost edge of the multilayer pattern in contact with the transparent substrate is 50 Å to 1000 Å when viewed in cross section.

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