KR20220091120A - Blankmask and Photomask for Flat Panel Display - Google Patents

Abstract

The present invention is a blank mask for a flat panel display (FPD) provided with a light blocking film on a transparent substrate, wherein the light blocking film is a light blocking layer composed of two or more multilayer films including at least a lower light blocking layer and an upper light blocking layer, and an upper and lower portion of the light blocking layer It includes a lower anti-reflection layer and an upper anti-reflection layer respectively formed on the.
In the present invention, an anti-reflection layer having a low reflectance of 5% or less with respect to exposure light used in the exposure process is disposed on the upper and lower surfaces of the light-shielding layer, and the light-shielding layer is etched so that the cross-sectional shape of the light-shielding layer has a reverse slope. to form with
Accordingly, it is possible to minimize reflection and re-reflection of exposure light by the light-shielding film, and to minimize the T top and tail of the light-shielding film to improve the precision of a pattern transferred using a photomask, especially in the overlapping exposure area. precision can be improved.

Description

Blankmask and Photomask for Flat Panel Display

The present invention relates to a blank mask and a photomask for a flat panel display, and more particularly, a blank for a flat panel display capable of improving transfer pattern precision by forming a metal film to have a low reflectance with respect to exposure light used in an exposure process. It relates to a mask and a photomask manufactured using the same.

In a lithography process for manufacturing a device for a flat panel display (FPD: Flat Panel Display, hereinafter, FPD) including a liquid crystal display (LCD), organic light emitting diodes (OLED), etc., a photo manufactured from a blank mask A device is fabricated using a mask.

In the blank mask, a thin film containing a metal is formed on the main surface of a translucent substrate made of synthetic quartz glass or the like, and a resist film is formed on the thin film. Here, the thin film may be divided into a light shielding film, an antireflection film, a phase reverse film, a semitransmissive film, a reflective film, etc. according to optical characteristics, and two or more kinds of thin films among these thin films are used in combination.

The exposure light used to fabricate FPD devices is primarily based on a light source emitted from a mercury lamp, and is typically a composite exposure light comprising I-line (365 nm), H-line (405 nm) and Gline (436 nm). . On the other hand, as high-resolution implementation is emerging, the wavelength of exposure light such as K-line (303) and J-line (312 nm) is gradually shortened.

On the other hand, as the metal film pattern of the photomask manufactured using the blank mask generally has a reflectance of about 10%, there is a portion overlapped by exposure light reflected back by the panel and the exposure device during the exposure process. In this case, there is a problem in that the transfer pattern is incorrectly formed. Specifically, in the exposure process, a portion of the exposure light is reflected by the panel, and the reflected exposure light is reflected again from the front surface of the metal film pattern of the photomask and irradiated to the panel to form an incorrect transfer pattern on the panel. do. In addition, a portion of the exposure light irradiated from the exposure apparatus is reflected from the back surface of the metal film pattern of the photomask, and the reflected exposure light is re-reflected by the exposure apparatus and transferred to the panel, thereby forming an incorrect transfer pattern.

As described above, there arises a problem in that the pattern is formed by moving or the pattern is formed to be smaller or larger than a required size in the overlapping exposure portion due to the re-reflection of the exposure light.

Accordingly, in order to solve the above problem, a blank mask including a light blocking layer and a light blocking film provided with an anti-reflection film on the upper and lower portions of the light blocking layer, respectively, and a photomask using the same were used.

However, in the structure, as the anti-reflection film having a high composition ratio of oxygen (O) and nitrogen (N) is further applied, the thickness of the entire light-shielding film becomes thicker, so that during wet etching, the exposure time to the etching solution becomes longer.

Accordingly, the wet etching time becomes longer from the transparent substrate to the upper layer, and the tail generated in the lower layer is stretched longer. Accordingly, a side inclination of the formed pattern is formed. During the transfer process using the pattern, the transfer pattern the precision is lowered.

The present invention has a low reflectance of 5% or less with respect to the exposure light to minimize reflection and re-reflection of the exposure light, and has an excellent etched cross-sectional shape to form a light-shielding film with a minimized T top and tail, and transfer using a photomask It is to provide a blank mask and a photomask for flat panel display that can improve the precision of the pattern to be used and can produce high-resolution FPD.

The present invention is a blank mask for a flat panel display (FPD) having a light blocking film on a transparent substrate, wherein the light blocking film is a light blocking layer made of two or more multilayer films including at least a lower light blocking layer and an upper light blocking layer, and an upper portion of the light blocking layer It includes a lower anti-reflection layer and an upper anti-reflection layer respectively formed thereunder.

The multi-layered light blocking layer, lower anti-reflection layer and upper anti-reflection layer are made of chromium (Cr) or a chromium (Cr) compound such as CrN, CrO, CrC, CrCO, CrCN, CrON, and CrCON.

The multi-layered light blocking layer has a higher content of carbon (C) from the transparent substrate to the upper portion so that the etching rate becomes slower toward the upper portion.

The multi-layered light blocking layer has a higher nitrogen (N) content toward the transparent substrate so that the etching rate becomes slower toward the upper portion.

The multi-layered light-shielding layer contains 60at% to 90at% of chromium (Cr), 0 to 40at% of nitrogen (N), 0 to 10at% of oxygen (O), and 0 to 10at% of carbon (C). have

The lower anti-reflection layer and the upper anti-reflection layer have surface and back reflectances of 0.1% to 5%, respectively, with respect to exposure light of at least one specific wavelength among wavelengths of 300 nm to 450 nm.

The lower anti-reflection layer and the upper anti-reflection layer contain 20at% to 50at% of chromium (Cr), 30at% to 70at% of nitrogen (N), 10at% to 30at% of oxygen (O), and 0 to 10at of carbon (C). % of the content.

In the present invention, an anti-reflection layer having a low reflectance of 5% or less with respect to exposure light used in an exposure process is disposed on the upper and lower surfaces of the light-shielding layer, and the light-shielding layer is etched so that the cross-sectional shape of the light-shielding layer has a reverse slope. to form with

Accordingly, it is possible to minimize reflection and re-reflection of exposure light by the light-shielding film, and to minimize the T top and tail of the light-shielding film to improve the precision of a pattern transferred using a photomask, especially in the overlapping exposure area. precision can be improved.

In addition, since the pattern precision of the panel according to the transfer process can be improved, a finer pattern can be formed, so that a blank mask and a photomask capable of producing a high-resolution FPD can be manufactured.

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

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

1 is a cross-sectional view illustrating a blank mask for FPD according to the present invention, and FIG. 2 is a cross-sectional view illustrating a photomask for FPD according to the present invention. The blank mask and photomask according to the present invention are used in the manufacture of FPD devices including TFT-LCDs, OLEDs, and the like.

1 and 2, the blank mask according to the present invention includes a light blocking film 120 and a resist film 130 provided on a transparent substrate 110, and the light blocking film 120 includes a light blocking layer and an anti-reflection layer. include In addition, the photomask according to the present invention has a form in which stacks thereof are patterned.

The light blocking layer is formed of two or more multilayer films including at least a lower light blocking layer 122 and an upper light blocking layer 124 . The anti-reflection layer includes a lower anti-reflection layer 126 provided under the light blocking layer and an upper anti-reflection layer 128 provided above.

The transparent substrate 110 is a rectangular transparent substrate with one side of 300 mm or more, and may be formed of a synthetic quartz glass, a soda-lime glass substrate, an alkali-free glass substrate, a low thermal expansion glass substrate, or the like.

The light blocking layer including the lower light blocking layer 122 and the upper light blocking layer 124 is irradiated by an exposure device to prevent exposure light irradiated to the panel through a photomask from being transferred to a portion on the panel that does not require transfer. plays a role in blocking

The upper anti-reflection layer 128 reflects the exposure light so that when a portion of the exposure light passing through the photomask is reflected by the panel in the exposure process, the exposure light reflected from the panel is not reflected back toward the panel from the lower surface of the photomask. function to prevent. In addition, the lower anti-reflection layer 126 prevents the exposure light irradiated from the exposure apparatus from being reflected from the upper surface of the photomask toward the exposure apparatus, thereby preventing the reflected exposure light from being reflected back by the exposure apparatus and irradiated to the panel. do

The lower light blocking layer 122 , the upper light blocking layer 124 , the lower anti-reflection layer 126 , and the upper anti-reflection layer 128 are chromium (Cr), aluminum (Al), cobalt (Co), tungsten (W), and molyb. Denium (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), Containing one or more of sodium (Na), hafnium (Hf), niobium (Nb), and silicon (Si), or one of nitrogen (N), oxygen (O), and carbon (C) in the material It further comprises the above substances.

In detail, the lower light blocking layer 122 , the upper light blocking layer 124 , the lower anti-reflection layer 126 and the upper anti-reflection layer 128 are chrome (Cr) or CrN, CrO, CrC, CrCO, CrCN, CrON, CrCON, such as It is preferable to form with a chromium (Cr) compound.

The lower light blocking layer 122 , the upper light blocking layer 124 , the lower anti-reflection layer 126 , and the upper anti-reflection layer 128 are all formed of chromium (Cr) or a chromium compound. The etching rate of each layer constituting the light blocking film 120 by adjusting the content of at least one of chromium (Cr), nitrogen (N), oxygen (O), and carbon (C) included in each layer to minimize the inclination and the etched cross-sectional shape of the entire light blocking layer 120 is adjusted.

The light blocking layer including the lower light blocking layer 122 and the upper light blocking layer 124 is a multilayer film composed of two or more layers, and when a pattern is formed through etching, each layer is sequentially or sequentially formed so that the cross-sectional shape has a reverse slope. It is preferable that the compositions are configured to be different. That is, the light blocking layer is configured such that the etching rate is slowed in a direction closer to the upper anti-reflection layer 128 .

For example, the etching rate of the light blocking layer may be controlled by the content of carbon (C). The content of the carbon (C) may be controlled by forming the film by adjusting the atmosphere of the carbon (C) gas that may be included when the light blocking layer is formed. That is, when the lower light blocking layer 122 is formed in the deposition process of the light blocking film 120 , the concentration of carbon (C) or a gas containing carbon (C) is lower than that of one or more of the upper layers, or carbon (C) .

In addition, the etching rate of the light blocking layer may be controlled by the content of nitrogen (C). That is, the content of nitrogen (N) is lower from the lower light blocking layer 122 to the upper light blocking layer 124, or the etch rate is lowered toward the upper side by not containing nitrogen (N). The cross-sectional shape may be formed to have a reverse inclination.

In addition, the content of at least one of nitrogen (N), oxygen (O), and carbon (C) may be adjusted together to form a cross-sectional shape to have a reverse inclination.

On the other hand, in the light blocking layer composed of two or more multilayer films including the lower light blocking layer 122 and the upper light blocking layer 124, as the content of oxygen (O) and nitrogen (N) increases, the light transmittance of the film increases, which increases the light blocking property It is undesirable for the content of oxygen (O) and nitrogen (N) to be high due to the nature of the light-shielding layer, which should be high. However, when the thickness of the light-shielding layer is thick, sufficient light-shielding property may be secured even if the content of oxygen (O) and nitrogen (N) is increased. Therefore, the light-shielding film patterns contain oxygen (O) and nitrogen (N) to a certain extent, and the content of oxygen (O) and nitrogen (N) is set below a certain level so as to secure the light-shielding properties required for the light-shielding film pattern. it is preferable

Accordingly, when each layer of the light blocking layer including the lower light blocking layer 122 and the upper light blocking layer 124 is made of a chromium (Cr) compound, chromium (Cr) is 60at% to 90at%, nitrogen (N) has a content of 0 to 40 at%, 0 to 10 at% of oxygen (O), and 0 to 10 at% of carbon (C).

When the amount of chromium (Cr) is 60 at% or less, it is difficult to secure the required light blocking properties, and when it is 90 at% or more, the etching time of the light blocking layer is excessively long. When the nitrogen (N) content is 40at% or more, the content of chromium (Cr) is reduced, making it difficult to secure the required light blocking properties, and when the nitrogen (N) is 10at% or less, the etching time is prolonged and it is difficult to secure the required optical density.

Specifically, when the content of nitrogen (N) is increased, the optical density is decreased, and therefore, it is preferable that the content of nitrogen (N) is decreased in order to increase the optical density. On the other hand, the etching time decreases as the content of nitrogen (N) increases, and the etching time increases as the content of carbon (C) increases. Accordingly, the etching time can be increased by compensating for the time shortened by nitrogen (N) with carbon (C), thereby adjusting the total etching time of the light blocking layer to a required time. If the content of carbon (C) is 10at% or more, the etching time is excessively increased, so it is preferably 10at% or less. In the case of oxygen (O), when the content is increased, the optical density is greatly reduced, and the transmittance is greatly increased. Therefore, when oxygen (O) is contained, the light-shielding property decreases and it is difficult to function as a light-shielding layer. Therefore, the light-shielding layer preferably has a low or no oxygen (O) content.

As described above, the function of blocking the exposure light is mainly performed by the light blocking layer of the light blocking film 120 , and minimizing the reflection of the exposure light is mainly performed by the antireflection layer. Therefore, the light-shielding layer should have a large light-shielding effect of exposure light, and in addition to that, it should meet the general requirements such as an etching time. In addition, the anti-reflection layer should be configured to have a low surface reflectance to prevent reflection or re-reflection of exposure light. Preferably, exposure light having one or more specific wavelengths among 300 nm to 450 nm wavelengths mainly used for pattern formation of FPD panels. It is configured to have surface and back reflectance of 0.1% to 5%, respectively.

To this end, the lower anti-reflection layer 126 and the upper anti-reflection layer 128 contains 20at% to 50at% of chromium (Cr), 30at% to 70at% of nitrogen (N), 10at% to 30at% of oxygen (O), Carbon (C) has a content of 0 to 10 at%. Since the lower anti-reflection layer 126 and the upper anti-reflection layer 128 are formed for the main purpose of preventing reflection rather than blocking light, the content of chromium (Cr) is configured to be less than that of the light blocking layer. In addition, the content of chromium (Cr) in the lower anti-reflection layer 126 and the upper anti-reflection layer 128 depends on the content of other materials that determine the reflectance characteristics such as nitrogen (N), oxygen (O), and carbon (C). is decided The nitrogen (N) content of 30at% to 70at% is for obtaining a specific reflectance characteristic in a specific wavelength band, and specifically, a reflectance of 5% or less with respect to exposure light of one or more wavelengths of 300 nm to 450 nm. is to get The content of 10at% to 30at% of oxygen (O) is also for obtaining a reflectance of 5% or less with respect to exposure light having at least one wavelength among wavelengths of 300 nm to 450 nm. The carbon (C) functions to control the etching rate of the anti-reflection layer increased by nitrogen (N), and if the content is 10 at% or more, the etching time is excessively increased, so it is preferably 10 at% or less.

The light blocking layer 120 including the lower light blocking layer 122 , the upper light blocking layer 124 , the lower anti-reflection layer 126 , and the upper anti-reflection layer 128 is formed by a sputtering process using a chromium (Cr) target. In this case, in the sputtering process, an inert gas such as argon (Ar) and a reactive gas including at least one of nitrogen (N), carbon (C), and oxygen (O) are selectively used.

The lower light blocking layer 122 , the upper light blocking layer 124 , the lower anti-reflection layer 126 , and the upper anti-reflection layer 128 are each formed as a single layer, or in the form of a multilayer film or a continuous film of at least two layers. The multilayer film refers to a film in which the composition or composition ratio of each layer is different, and the continuous film refers to a film in which the composition or composition ratio is continuously changed by changing process parameters such as process power, pressure, and gas composition in a state in which plasma is discharged.

The lower light blocking layer 122 , the upper light blocking layer 124 , the lower anti-reflection layer 126 , and the upper anti-reflection layer 128 each have a thickness of 50 Å to 1,500 Å, and the total thickness of the light blocking film 120 is 1,000 Å 1,750 Å.

The thickness of each of the lower light blocking layer 122, the upper light blocking layer 124, the lower anti-reflection layer 126, and the upper anti-reflection layer 128 is as described below in consideration of the composition and composition ratio of each layer as described above. It is set to satisfy the same characteristics such as optical density, extinction coefficient, and refractive index. That is, in the present invention, the respective numerical values and combinations of the thickness, composition, and composition ratio of each layer are set to ultimately realize the light blocking performance of the light blocking film 120 and the low reflectivity of the antireflection layers 126 and 128 . For example, when the lower light blocking layer 122 and the upper light blocking layer 124 have the same thickness, the higher the optical density, the higher the light blocking degree. In the case of forming 124 , the required light blocking degree can be obtained by increasing the thickness of the light blocking layer 214 .

In order for the light blocking film 120 to function to minimize transmission and reflection of exposure light in the exposure process, the light blocking film 120 is preferably configured to have an optical density of 2.5 to 7.0. The lower anti-reflection layer 126 and the upper anti-reflection layer 128 have a very low extinction coefficient (k), and when the extinction coefficient (k) is low, the optical density is low. It corresponds to the optical density of the layer 122 and the upper light blocking layer 124 .

Since the light blocking layer including the lower light blocking layer 122 and the upper light blocking layer 124 is a thin film for the purpose of minimizing light transmission for exposure light, the higher the extinction coefficient (k), the more suitable, and the extinction coefficient of the light blocking layer In order to increase (k), the combination of the composition (or composition ratio) of the light-shielding layer and the thickness of the light-shielding layer may be appropriately adjusted. In the light blocking layer including the lower light blocking layer 122 and the upper light blocking layer 124 , the higher the extinction coefficient k is, the higher the absorption rate for exposure increases, so that the optical density of the light blocking film 120 as a whole increases. In addition, as the thickness of the light blocking layer 214 increases, the optical density of the entire light blocking layer 120 may increase in proportion to this. In order to satisfy the optical density 2.5 to 7.0 required for the light blocking film 120 or the light blocking layer including the lower light blocking layer 122 and the upper light blocking layer 124, the light blocking layer has a thickness of 1.8 to 1,500 Å. It is desirable to have an extinction coefficient (k) of 2.8.

As described above, the lower anti-reflection layer 126 and the upper anti-reflection layer 128 need to have increased injection efficiency of exposure light in order to have a low surface reflectance of 5% or less. It is desirable to have a coefficient k. In the case of the refractive index n, the transmittance is high from the high refractive index to the low side, and the transmittance is low from the low to high side. Therefore, in order to constrain the light source inside the lower anti-reflection layer 126 and the upper anti-reflection layer 128 to have a low reflectance, the lower anti-reflection layer 126 and the upper anti-reflection layer 128 have a higher refractive index than the light blocking layer. It is preferable to have (n). A preferable numerical range of the refractive index n is 1.5 to 2.0 for the light blocking layer, and 2.0 to 3.0 for the lower anti-reflection layer 126 and the upper anti-reflection layer 128 . In this numerical range, it was confirmed that the required function of each layer, that is, the expression effect of the light blocking function by the light blocking layer and the reflection prevention function by the antireflection layer was most optimized.

The light blocking film 120 including the lower light blocking layer 122, the upper light blocking layer 124, the lower anti-reflection layer 126 and the upper anti-reflection layer 128 configured as described above transmits and transmits exposure light in the exposure process. By minimizing the effect of reflection, the precision of the pattern can be improved, a finer pattern can be formed, and the resolution can be improved.

As mentioned above, although the present invention is specifically described through the structure of the present invention with reference to the drawings, the structure is used only for the purpose of illustration and description of the present invention and limits the meaning or the scope of the present invention described in the claims. It is not intended to be limiting. Therefore, those skilled in the art will understand that various modifications and equivalent other structures are possible from the structure. Therefore, the true technical protection scope of the present invention will have to be determined by the technical matters of the claims.

110: transparent substrate 120: light blocking film
122: lower light blocking layer 124: upper light blocking layer
126: lower anti-reflection layer 230: upper anti-reflection layer

Claims (11)

As a blank mask for FPD (Flat Panel Display) provided with a light-shielding film on a transparent substrate,
The light-shielding film is a blank mask for FPD comprising a light-shielding layer consisting of two or more multilayer films including at least a lower light-shielding layer and an upper light-shielding layer, and a lower anti-reflection layer and an upper anti-reflection layer respectively formed on the upper and lower portions of the light-shielding layer.
The method of claim 1,
The multi-layered light blocking layer, the lower anti-reflection layer and the upper anti-reflection layer are made of chromium (Cr) or a chromium (Cr) compound such as CrN, CrO, CrC, CrCO, CrCN, CrON, CrCON. .
3. The method of claim 2,
The blank mask for FPD, characterized in that the multi-layered light blocking layer has a higher content of carbon (C) from the transparent substrate to the upper portion so that the etching rate becomes slower toward the upper portion.
3. The method of claim 2,
The blank mask for FPD, characterized in that the multi-layered light blocking layer has a higher nitrogen (N) content in the direction of the transparent substrate so that the etching rate becomes slower toward the upper portion.
3. The method of claim 2,
The multi-layered light-shielding layer contains 60 at% 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). Blank mask for FPD, characterized in that it has.
The method of claim 1,
The blank mask for FPD, characterized in that the lower anti-reflection layer and the upper anti-reflection layer have surface and back reflectances of 0.1% to 5%, respectively, with respect to exposure light of one or more specific wavelengths among wavelengths of 300 nm to 450 nm.
3. The method of claim 2,
The lower anti-reflection layer and the upper anti-reflection layer contain 20at% to 50at% of chromium (Cr), 30at% to 70at% of nitrogen (N), 10at% to 30at% of oxygen (O), and 0 to 10at of carbon (C). A blank mask for FPD, characterized in that it has a content of %.
The method of claim 1,
The light blocking film has a thickness of 1,000 Å to 1,750 Å, and the lower light blocking layer, the upper light blocking layer, the lower anti-reflection layer and the upper anti-reflection layer each have a thickness of 50 Å to 1,500 Å.
The method of claim 1,
The blank mask for FPD, characterized in that the light-shielding film has an optical density of 2.5 to 7.0.
The method of claim 1,
The light blocking layer has an extinction coefficient (k) of 1.8 to 2.8 at a thickness of 50 Å to 1,500 Å, and a refractive index (n) of 1.5 to 2.0,
The blank mask for FPD, characterized in that the lower anti-reflection layer and the upper anti-reflection layer has a refractive index (n) of 2.0 to 3.0.
A photomask for FPD manufactured using the blank mask for FPD of claim 1 to 10.

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