KR102719838B1 - Blankmask and Photomask for use in Flat Panel Display - Google Patents

Abstract

A blank mask for a flat panel display comprises a light-blocking film and an anti-reflection film on a transparent substrate, and the anti-reflection film comprises an anti-static layer for preventing charge accumulation. The anti-static layer contains 30 to 60 at% of chromium (Cr), 20 to 60 at% of nitrogen (N), 10 to 40 at% of oxygen (O), and 0 to 10 at% of carbon (C). The anti-static layer suppresses charge accumulation due to charging occurring in a metal film pattern provided on a photomask, thereby preventing damage to the metal film pattern.

Description

{Blankmask and Photomask for use in Flat Panel Display}

The present invention relates to a blank mask and a photomask for a flat panel display, and more particularly, to a blank mask and a photomask for a flat panel display capable of preventing pattern damage caused by static electricity and overcurrent.

In the lithography process for manufacturing semiconductor devices or flat panel display (FPD) devices including TFT-LCD (Thin Film Transistor Liquid Crystal Display), OLED (Organic Light Emitting Diode), and PDP (Plasma Display Pannel), pattern transfer is performed using a photomask manufactured from a blank mask.

The blank mask has a structure in which a metal thin film is formed on the main surface of a light-transmitting substrate such as synthetic quartz glass, and a resist film is formed on the thin film. Here, the thin film can be divided into a light-shielding film, an antireflection layer, a phase shift film, a semi-transparent film, a reflective film, etc., depending on the optical characteristics, and two or more of these thin films are sometimes used in combination. The photomask is manufactured by exposing and developing the resist film of the blank mask to form a resist film pattern, and then using this as an etching mask to form a light-shielding film pattern.

In a photomask, static electricity is generated due to contact, friction, peeling, ion adsorption, etc. between the photomask and the substrate during use. At this time, the contact area between the photomask and the substrate, contact time, friction frequency, attachment/detachment speed, temperature difference, etc. are major factors that affect the size of the charge in the photomask. When static electricity is generated inside the photomask due to these factors, the problem of damage to the light-shielding film pattern made of a metal film occurs.

Specifically, when performing an exposure process to form a pattern of a display panel using a photomask, the static electricity induced by the non-transparent shading film pattern made of a metal film is charged, and functions like a capacitor to accumulate charges, and the accumulated charges can be discharged at vulnerable points such as the periphery of the pattern. In this way, the shading film pattern is damaged and destroyed in the process of the accumulated charges being discharged at the vulnerable points. This causes defects in the transferred pattern, and the problem of an increased product defect rate arises.

Meanwhile, in order to solve the problem of damage to the metal pattern of the photomask due to static electricity, methods such as controlling the humidity in the clean room, using an antistatic agent, or installing an ionizer have been used in the past. In the case of these conventional technologies for preventing damage to the photomask, there were problems such as concerns about corrosion of the equipment due to high humidity, problems such as deterioration of product quality due to chemicals used as antistatic agents, or problems such as the need to install additional components such as ionizers.

The purpose of the present invention is to provide a blank mask and a photomask for a flat panel display capable of preventing damage to a metal film pattern by suppressing charge accumulation due to electrification occurring in a metal film pattern provided on a photomask.

A blank mask for a flat panel display according to the present invention comprises: a transparent substrate; a light-shielding film provided on the transparent substrate; and an anti-reflection film provided on at least one of an upper portion and a lower portion of the light-shielding film; wherein the anti-reflection film is characterized by including an antistatic layer for preventing charge accumulation.

The above-mentioned anti-static layer contains chromium (Cr), nitrogen (N), and oxygen (O), and specifically contains 30 to 60 at% of chromium (Cr), 20 to 60 at% of nitrogen (N), 10 to 40 at% of oxygen (O), and 0 to 10 at% of carbon (C).

The above anti-reflection film may further include a reflective layer that reflects a portion of exposure light, and a reflectivity control layer that controls reflectivity for exposure light of a specific wavelength.

It is preferable that the above-mentioned antistatic layer is positioned as the lowest layer within the above-mentioned antireflection film, and more preferably, the above-mentioned antireflection film is laminated in the order of the above-mentioned antistatic layer, the above-mentioned reflective layer, and the above-mentioned reflectivity control layer on the above-mentioned light shielding film.

The above reflection layer contains chromium (Cr) and nitrogen (N), and specifically contains 50 to 90 at% of chromium (Cr), 10 to 50 at% of nitrogen (N), and 0 to 10 at% of carbon (C).

The above reflectivity control layer contains chromium (Cr), nitrogen (N), and oxygen (O), and specifically contains 20 to 50 at% of chromium (Cr), 30 to 70 at% of nitrogen (N), 10 to 40 at% of oxygen (O), and 0 to 10 at% of carbon (C).

The above-mentioned antistatic layer has a thickness of 500 to 1500 Å, the above-mentioned reflective layer has a thickness of 50 to 1000 Å, and the above-mentioned reflectivity control layer has a thickness of 50 to 500 Å.

It is preferable that the above anti-reflection film is formed on top of the above light-shielding film.

The above-mentioned shade film has an optical density of 2.5 to 7.0 for exposure light of a composite wavelength including i-line, h-line, and g-line.

The above-described shade film may include one or more of materials selected from the group consisting of chromium (Cr), aluminum (Al), cobalt (Co), tungsten (W), molybdenum (Mo), vanadium (V), palladium (Pd), titanium (Ti), platinum (Pt), manganese (Mn), iron (Fe), nickel (Ni), cadmium (Cd), zirconium (Zr), magnesium (Mg), lithium (Li), selenium (Se), copper (Cu), yttrium (Y), sulfur (S), indium (In), tin (Sn), boron (B), beryllium (Be), sodium (Na), tantalum (Ta), hafnium (Hf), niobium (Nb), and silicon (Si), or may be configured by further including one or more of nitrogen (N), oxygen (O), and carbon (C) in the above-described materials.

According to another aspect of the present invention, a photomask for a flat panel display is provided, manufactured using a blank mask for a flat panel display having the above-described configuration.

The present invention forms a light-shielding layer that minimizes the movement of charges on a light-shielding film to prevent charge accumulation due to static electricity, thereby minimizing damage to a photomask pattern caused by discharge of charges accumulated during use of the photomask. Accordingly, defects in the transferred pattern can be minimized, thereby improving productivity.

FIG. 1 is a cross-sectional view illustrating a blank mask for FPD according to the present invention.

FIG. 1 is a cross-sectional view illustrating a blank mask for a FPD (Flat Panel Display) according to the present invention.

The blank mask according to the present invention is a blank mask for FPDs including liquid crystal displays (LCDs), plasma display panels (PDPs), OLEDs, etc. The blank mask has a structure in which a rear anti-reflection film (216), a light-shielding film (214), an anti-reflection film (206), and a resist film are sequentially laminated on a transparent substrate (202).

The transparent substrate (202) is a square transparent substrate with one side of 300 mm or more, and can be formed of synthetic quartz glass, a soda lime glass substrate, an alkali-free glass substrate, a low thermal expansion glass substrate, etc.

The shade film (214) serves to block the exposure light used in the exposure process so that it is not transferred to a panel portion where transfer is not required. The shade film (214) must have a large light-blocking effect against the exposure light, and must also satisfy other requirements such as the etching time generally required.

The shade film (214) is formed by including at least one material selected from the group consisting of chromium (Cr), aluminum (Al), cobalt (Co), tungsten (W), molybdenum (Mo), vanadium (V), palladium (Pd), titanium (Ti), platinum (Pt), manganese (Mn), iron (Fe), nickel (Ni), cadmium (Cd), zirconium (Zr), magnesium (Mg), lithium (Li), selenium (Se), copper (Cu), yttrium (Y), sulfur (S), indium (In), tin (Sn), boron (B), beryllium (Be), sodium (Na), tantalum (Ta), hafnium (Hf), niobium (Nb), and silicon (Si), or is formed by further including at least one of nitrogen (N), oxygen (O), and carbon (C) in the above materials.

The light shielding film (214) is preferably formed of chromium (Cr) or a chromium (Cr) compound such as CrN, CrO, CrC, CrCO, CrCN, CrON, or CrCON. At this time, the light shielding film (214) is formed of a material containing 50 to 90 at% of chromium (Cr), 0 to 40 at% of nitrogen (N), 0 to 10 at% of oxygen (O), and 0 to 10 at% of carbon (C). Here, when the content of nitrogen (N), oxygen (O), and carbon (C) is 0 at%, this means that these elements are not included. That is, nitrogen, oxygen, and carbon may be selectively included. When chromium (Cr) is 50 at% or less or nitrogen (N) is 40 at% or more, the content of chromium (Cr) decreases, which reduces the optical density of the required light shielding film, making it difficult to secure light shielding properties. In the case of oxygen (O), the content is preferably 10 at% or less because the optical density decreases significantly and the transmittance increases significantly when the content increases. Carbon (C) may be included to control the etching time of the light shielding film (214), and when it is 10 at% or more, the etching time increases excessively, which has a bad effect on the formation of the etched cross-section.

The shade film has a thickness of 200 to 1,500 Å. The shade film (214) preferably has an optical density of 2.5 to 7.0 for exposure light of a composite wavelength including i-line, h-line, and g-line, and more preferably has an optical density of 3.0 to 6.0.

The shade film (214) is formed by a sputtering process using a chromium (Cr) target. At this time, in the sputtering process, an inert gas such as argon (Ar) and a reactive gas containing at least one of nitrogen (N), carbon (C), and oxygen (O) are selectively used.

The antireflection film (206) has the function of suppressing the reflection of exposure light on the surface. In addition, the antireflection film of the present invention also has the function of minimizing the movement of charges in order to prevent charge accumulation due to electrification. To this end, the antireflection film (206) of the present invention has a structure in which an antistatic layer (212), a reflective layer (208), and a reflectivity control layer (208) are sequentially laminated on a light shielding film (214).

The antistatic layer (212) has a function of preventing charge from accumulating on the thin film during the exposure process. That is, the antistatic layer (212) has a function of preventing charge movement within the antireflection film (206) to minimize charge accumulation occurring in the photomask.

The antistatic layer (212) is formed of a material containing chromium (Cr), nitrogen (N), and oxygen (O). Specifically, the antistatic layer (212) is formed of a material containing 30 to 60 at% of chromium (Cr), 20 to 60 at% of nitrogen (N), 10 to 40 at% of oxygen (O), and 0 to 10 at% of carbon (C). When the content of nitrogen (N) is 20 at% or less or the content of oxygen (O) is 10 at% or less, charges increase within the antistatic layer (212), making it difficult to prevent the accumulation of charges charged in the photomask and also affecting the occurrence of ESD (Electrostatic Discharge). When the content of nitrogen (N) is 60 at% or more or the content of oxygen (O) is 40 at% or more, the prevention of charge accumulation is highly effective, but the transmittance of the thin film increases, so that the thickness must be excessively increased in order to meet the required optical density. Carbon (C) may be included to control the etching time of the antistatic layer (212), and when it is 10 at% or more, the etching time increases excessively, which has a bad effect on the formation of the etched cross-section. Here, the range of the carbon (C) content being 0 to 10 at% means that carbon may be selectively included. That is, carbon may not be included, and when included, it is desirable to include it in a content of less than 10 at%.

The reflection layer (210) has the function of reflecting a portion of the exposure light. The reflection layer (210) is formed of a material containing chromium (Cr) and nitrogen (N). Specifically, the reflection layer (210) is formed of a material containing 50 to 90 at% of chromium (Cr), 10 to 50 at% of nitrogen (N), and 0 to 10 at% of carbon (C). When the chromium (Cr) content is less than or equal to 50 at% or the nitrogen (N) content is more than or equal to 50 at%, the light reflectivity is too low to perform the function as the reflection layer (210), and when the chromium (Cr) content is more than or equal to 90 at% or the nitrogen (N) content is less than or equal to 10 at%, the light reflectivity is too high to secure the reflectivity required for the wavelength of the exposure light. Carbon (C) may be included to control the etching time of the reflection layer (210), and when it is more than 10 at%, the etching time increases excessively, which has a bad effect on the formation of an etched cross-section. Here, the range of carbon (C) content being 0 to 10 at% means that carbon can be selectively included. That is, carbon may not be included, and if included, it is desirable for it to be included in a content of less than 10 at%.

The reflectivity control layer (208) has the function of controlling the reflectivity for exposure light of a specific wavelength. The reflectivity control layer (208) is formed of a material containing chromium (Cr), nitrogen (N), and oxygen (O). Specifically, the reflectivity control layer (208) is formed of a material containing 20 to 50 at% of chromium (Cr), 30 to 70 at% of nitrogen (N), 10 to 40 at% of oxygen (O), and 0 to 10 at% of carbon (C). If the content of nitrogen (N) is 30 at% or less or the content of oxygen (O) is 10 at% or less, it is difficult to prevent the accumulation of surface charges and the prevention of surface reflection is also affected. If the content of nitrogen (N) is 30 at% or less or the content of oxygen (O) is 10 at% or less, it is difficult to prevent the accumulation of surface charges and the prevention of surface reflection is also affected. If the nitrogen (N) content is 70 at% or more or the oxygen (O) content is 40 at% or more, it is effective in preventing charge accumulation, but the reflectivity of the surface goes out of the controllable range. Carbon (C) may be included to control the etching time of the reflectivity adjustment layer (208), and if it is 10 at% or more, the etching time increases excessively, which has a bad effect on the formation of the etched cross-section. Here, the range of the carbon (C) content being 0 to 10 at% means that carbon can be selectively included. That is, carbon may not be included, and if it is included, it is desirable that it be included in a content of less than 10 at%.

The anti-static layer (212) is preferably positioned at the lowest layer within the anti-reflection film (206). More preferably, the anti-reflection film (206) has a structure in which an anti-static layer (212), a reflection layer (210), and a reflectivity control layer (208) are sequentially laminated on a light shielding film (216). The anti-reflection film (206) of this structure may be formed in the form of a multilayer film in which three layers are separated, or may be formed in the form of a continuous film in which the composition thereof is continuously changed so that each layer (212, 210, 208) is formed. Here, the continuous film means a thin film in which the composition is continuously changed by gradually changing process variables such as process power, pressure, and gas composition while plasma is discharged.

The antistatic layer (212) has a thickness of 500 to 1,500 Å, the reflective layer (210) has a thickness of 50 to 1,000 Å, and the reflectivity control layer (208) has a thickness of 50 to 500 Å. When the thickness of the antistatic layer (212) is 500 Å or less, the conductivity of the film increases, thereby increasing the charging effect. Therefore, it is preferable that the antistatic layer (212) has a thickness of 500 Å or more.

The back anti-reflection film (216) prevents the exposure light irradiated from the exposure device from being reflected from the upper surface of the photomask toward the exposure device, thereby preventing the reflected exposure light from being re-reflected by the exposure device and irradiated onto the panel. The back anti-reflection film (216) may be formed of a material containing 20 to 50 at% of chromium (Cr), 30 to 70 at% of nitrogen (N), 10 to 40 at% of oxygen (O), and 0 to 10 at% of carbon (C), similar to the reflectivity control layer (208) of the uppermost layer.

As described above, according to the present invention, the accumulation of charges on the pattern surface of the photomask is prevented by the antireflection film including the function of preventing the movement of charges within the photomask during electrification. That is, the present invention can reduce the conductivity of the photomask by providing an antireflection film (206) with an antistatic layer (212) composed of nitride oxide and having the properties of an insulator. Accordingly, the movement of charges to the photomask pattern surface is minimized, and the accumulation of charges is prevented, thereby suppressing the occurrence of ESD. Accordingly, static electricity generated in the photomask pattern is suppressed, and pattern defects due to static electricity are minimized.

Above, the present invention has been specifically described through the structure of the present invention with reference to the drawings, but the structure has been used only for the purpose of illustrating and explaining the present invention, and has not been used to limit the meaning or the scope of the present invention described in the claims. Therefore, those skilled in the art of the present invention will understand that various modifications and equivalent other structures are possible from the structure. Accordingly, the true technical protection scope of the present invention should be determined by the technical details of the claims.

202: Transparent substrate 206: Anti-reflection film
208: Reflectivity control layer 210: Reflection layer
212: Anti-static layer 214: Light-blocking layer
216: Back anti-reflection film 220: Resist film

Claims (16)

transparent substrate;
A light-shielding film provided on the transparent substrate; and
An anti-reflection film provided on at least one of the upper and lower portions of the above-mentioned shade film;
Including,
The above antireflection film includes an antistatic layer for preventing charge accumulation, a reflective layer for reflecting a portion of the exposure light, and a reflectivity control layer for controlling the reflectivity for exposure light of a specific wavelength.
The above-mentioned antistatic layer contains 30 to 60 at% chromium (Cr), 20 to 60 at% nitrogen (N), 10 to 40 at% oxygen (O), and 0 to 10 at% carbon (C), the above-mentioned reflective layer contains 50 to 90 at% chromium (Cr), 10 to 50 at% nitrogen (N), and 0 to 10 at% carbon (C), and the above-mentioned reflectivity control layer contains 20 to 50 at% chromium (Cr), 30 to 70 at% nitrogen (N), 10 to 40 at% oxygen (O), and 0 to 10 at% carbon (C).
A blank mask for a flat panel display, characterized in that the antistatic layer has a thickness of 500 to 1500 Å, the reflective layer has a thickness of 50 to 1000 Å, and the reflectivity control layer has a thickness of 50 to 500 Å.
delete delete delete In paragraph 1,
A blank mask for a flat panel display, characterized in that the anti-static layer is located at the lowest layer within the anti-reflection film.
In paragraph 1,
A blank mask for a flat panel display, characterized in that the anti-reflection film is laminated in the order of the antistatic layer, the reflection layer, and the reflectivity control layer on the light shielding film.
delete delete delete delete delete delete In paragraph 1,
A blank mask for a flat panel display, characterized in that the anti-reflection film is formed on top of the light-shielding film.
In paragraph 1,
A blank mask for a flat panel display, characterized in that the above-mentioned light shielding film has an optical density of 2.5 to 7.0 for exposure light of a composite wavelength including i-line, h-line, and g-line.
In paragraph 1,
A blank mask for a flat panel display, characterized in that the above-mentioned shade film contains at least one material selected from the group consisting of chromium (Cr), aluminum (Al), cobalt (Co), tungsten (W), molybdenum (Mo), vanadium (V), palladium (Pd), titanium (Ti), platinum (Pt), manganese (Mn), iron (Fe), nickel (Ni), cadmium (Cd), zirconium (Zr), magnesium (Mg), lithium (Li), selenium (Se), copper (Cu), yttrium (Y), sulfur (S), indium (In), tin (Sn), boron (B), beryllium (Be), sodium (Na), tantalum (Ta), hafnium (Hf), niobium (Nb), and silicon (Si), or further contains at least one of nitrogen (N), oxygen (O), and carbon (C) in the above-mentioned material.
A photomask for a flat panel display manufactured using the blank mask for a flat panel display of any one of claims 1, 5, 6, 13, 14, and 15.

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