KR20070071718A - Halftone mask for liquid crystal display and method for manufacturing the same - Google Patents

Abstract

A halftone mask for an LCD(Liquid Crystal Display) and a method for manufacturing the same are provided to lower the requirement level for accuracy of overlay, thereby increasing the efficiency of process, by improving the structure of the halftone mask. A halftone mask comprises a transparent substrate(100), a blocking pattern(110) formed on one surface of the transparent substrate correspondingly to a blocking region, a transflective pattern(120) formed on the other surface of the transparent substrate correspondingly to a transflective region, and a transmissive region defined on the transparent substrate correspondingly to a region other than the blocking region and the transflective region.

Description

Halftone mask for liquid crystal display and manufacturing method thereof {Halftone mask for liquid crystal display and method for manufacturing the same}

1 is a plan view illustrating some pixels of a conventional array substrate for a liquid crystal display device.

FIG. 2 is a cross-sectional view illustrating the thin film transistor of FIG. 1.

3A to 3K are cross-sectional views illustrating processes for manufacturing a halftone mask for a liquid crystal display according to the related art.

4 is a view for explaining the problem of the conventional halftone mask for a liquid crystal display device.

5 is a schematic cross-sectional view of a halftone mask for a liquid crystal display according to an exemplary embodiment of the present invention.

6 and 7 are graphs showing transmission characteristics and exposure states of the halftone mask of FIG. 5, respectively.

8 is a flowchart illustrating a method of manufacturing a halftone mask for a liquid crystal display according to an exemplary embodiment of the present invention.

9A to 9I are cross-sectional views illustrating processes of manufacturing a halftone mask for a liquid crystal display according to an exemplary embodiment of the present invention.

(Explanation of symbols for the main parts of the drawing)

100: transparent substrate 110: blocking pattern

120: transflective pattern T: transmission area

S: blocking area H / T: transflective area

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a halftone mask and a method of manufacturing the same, and more particularly, to a halftone mask used in an exposure process of a liquid crystal display device and a method of manufacturing the same.

The liquid crystal display injects a liquid crystal material having anisotropic dielectric constant between the color filter substrate and the array substrate, which are upper and lower transparent insulating substrates, and adjusts the intensity of the electric field formed in the liquid crystal material to change the molecular arrangement of the liquid crystal material. The display device expresses a desired image by adjusting the amount of light transmitted through the transparent insulating substrate. As the liquid crystal display, a thin film transistor liquid crystal display (TFT LCD) using a thin film transistor (TFT) as a switching element is mainly used.

1 is a plan view illustrating some pixels of a conventional array substrate for a liquid crystal display device, and FIG. 2 is a cross-sectional view illustrating the thin film transistor of FIG. 1.

As shown, the array substrate is composed of a plurality of pixel regions P defined by gate lines 20 and data lines 30 that are orthogonal to each other, and each pixel region P includes a thin film transistor T that is a switching element. ), The pixel electrode 40, the storage capacitor C which is a storage capacitor, and the like.

Referring to FIG. 2, the thin film transistor T includes a gate electrode 21, a source electrode 31, a drain electrode 32, a semiconductor layer 12, and the like, and a source electrode 31 and a gate electrode 21. ) Is configured to be connected to the data line 30 and the gate line 20, respectively.

The gate insulating layer 11 is formed to cover the entire surface of the transparent insulating substrate 10 including the upper portion of the gate electrode 21. The semiconductor layer 12 is formed of an undoped amorphous silicon material on the gate insulating layer 11, and a region corresponding to the gate electrode 21 on the semiconductor layer 12 is defined as an active channel.

The ohmic contact layer 13 is formed at an interface between the source electrode 31 and the drain electrode 32 and the semiconductor layer 12, and is made of an n + hydrogenated amorphous silicon material doped with a high concentration of n-type impurities.

A passivation layer 14 made of an inorganic insulating material such as silicon nitride film SiNx or an organic insulating material is formed on the thin film transistor T, and a contact hole 41 exposing the drain electrode 32 is formed on the passivation film 14. ) Is formed. The pixel electrode 40 is connected to the drain electrode 32 through the contact hole 41 and is made of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO).

The data line 20 of FIG. 1 overlaps the semiconductor layer 12 of the thin film transistor T in a planar manner, and the storage capacitor C has a storage on gate structure and is formed on the pixel electrode 40. The metal electrode layer 30 'to be connected and the gate line 20' below it become upper and lower electrodes to form a metal / insulator / metal (M / I / M) structure.

The conventional array substrate for a liquid crystal display device basically has a first mask process for forming the gate line 20 and the gate electrode 21, and the semiconductor layer 12 and the ohmic contact layer 13 on the gate insulating layer 11. Forming a contact hole 41 on the passivation layer 14, forming a second mask process for forming the source electrode 31 and the drain electrode 32 on the left and right sides of the semiconductor layer 12, and forming the contact hole 41 on the passivation layer 14. It is common to manufacture through the 4 mask process and the 5th mask process which forms the pixel electrode 40 connected to the drain electrode 32 through the contact hole 41. FIG.

The mask process is a process that consumes a lot of raw materials and takes a long process time, which causes high manufacturing cost and yield reduction. Therefore, the number of mask processes required for manufacturing a liquid crystal display device is reduced, and the same mask is used. Even in this case, a halftone mask is used to solve the inconvenience of having to go through several steps.

By using a halftone mask, it is possible to simultaneously appropriately etch layers that are formed at different heights during the same process time.

3A to 3K are cross-sectional views illustrating processes for manufacturing a halftone mask for a liquid crystal display according to the related art.

First, the barrier layer 60 and the photoresist 70 are sequentially stacked on the transparent substrate 50 (FIG. 3A), and then the photoresist 70 is patterned by exposure and development to form the photoresist pattern 71. Is formed (FIG. 3B, 3C).

Next, wet etching the lower blocking layer 60 using the photoresist pattern 71 as a mask exposes a portion of the transparent substrate 50 to form a blocking pattern 61 (FIG. 3D).

Next, after removing and cleaning the photoresist pattern 71 by stripping (FIG. 3E), a semi-transmissive layer 80 is laminated on the entire surface (FIG. 3F), and the photoresist 90 is again front-sided. It is apply | coated to (FIG. 3g).

Next, the photoresist 90 is patterned by exposure and development to form a photoresist pattern 91 (FIG. 3H, FIG. 3I), and using the photoresist pattern 91 as a mask, the lower semitransmissive layer 80 Wet etching to form a transflective pattern 81 (FIG. 3J).

Next, the remaining photoresist pattern 91 is stripped and washed to complete a halftone mask in which the blocking pattern 61 and the transflective pattern 81 are formed on the transparent substrate 50 (FIG. 3K).

4 is a view illustrating a problem of a halftone mask for a liquid crystal display according to the related art, and illustrates an example of a mask process using a halftone mask manufactured through the same process as FIGS. 3A to 3K.

As shown in FIG. 4, the conventional halftone mask includes a blocking pattern 61, a semitransmissive pattern 81, and a blocking pattern formed in the blocking region S and the transflective region H / T on the transparent substrate 50, respectively. Since the pattern 61 or the transflective pattern 81 is not formed, the transparent substrate 50 is formed of a transparent region T exposed at a constant width.

Due to the configuration of the halftone mask, the exposure state of the photoresist PR applied on the transparent insulating substrate Glass in the exposure process is three states of blocking, transmissive, and transflective. After exposing with a halftone mask on the photoresist PR applied to the photoresist and developing it, the exposure amount is adjusted for each region so that the photoresist PR is completely removed or only part of the thickness is present depending on the position. .

However, in the conventional halftone mask, the transmittance of light (for example, transmittance of L1 and L2) is different depending on the region at the boundary where the blocking pattern 61 and the transflective pattern 81 are stacked as in R1. In the photoresist PR, as in the case of R2, a slope is generated, and thus the profile property is likely to deteriorate.

In addition, since there is no etching selectivity when etching the blocking pattern 61 and the semi-transmissive pattern 81 in the halftone mask manufacturing process, a high level of overlay accuracy is required in the stepped portion such as R1, which causes difficulties in the process. There was this. The blocking pattern 61 and the transflective pattern 81 may be collectively wetted to form a desired mask pattern. However, since the wet etching is isotropic, the material forming the transflective pattern 81 may be over etched. There was a problem that the formation of the transflective pattern 81 is difficult.

Accordingly, a technical problem of the present invention is to improve the profile characteristics of the photoresist in the region corresponding to the boundary portion where the blocking pattern or the transflective pattern is formed, and to reduce the required level of overlay accuracy, thereby increasing the efficiency of the process. It is to provide a halftone mask.

Another object of the present invention is to provide a method for manufacturing a halftone mask for a liquid crystal display device capable of efficiently manufacturing such a halftone mask.

Technical problems to be achieved by the present invention are not limited to the above-mentioned technical problems, and other technical problems not mentioned above will be clearly understood by those skilled in the art from the following description. Could be.

According to an aspect of the present invention, a halftone mask for a liquid crystal display device includes a transparent substrate, a blocking pattern formed in a blocking region of one surface of the transparent substrate, and a half of the other surface of the transparent substrate. And a transflective pattern formed in the transmissive region, and a transmissive region defined as a region other than the blocking region and the transflective region on the transparent substrate.

A method of manufacturing a halftone mask for a liquid crystal display according to an exemplary embodiment of the present invention may include forming a blocking layer on one surface of a transparent substrate, and patterning the blocking layer to form a blocking pattern in a blocking region of the transparent substrate. Forming a transflective layer on the other side of the transparent substrate, and forming a transflective pattern in the transflective region of the transparent substrate by patterning the transflective layer to exclude the blocking region and the transflective region. Defining the area as a transmissive area.

In the method of manufacturing a halftone mask for a liquid crystal display according to an exemplary embodiment of the present invention, after forming the blocking pattern, forming a protective film covering an upper portion of the blocking pattern on the entire surface of the transparent substrate, and semi-transparent After forming the pattern, it is preferable to further include the step of removing the protective film.

In the method of manufacturing a halftone mask for a liquid crystal display according to an exemplary embodiment of the present disclosure, the forming of the blocking pattern may include coating and exposing a photoresist on the blocking layer, and then developing the exposed photoresist. Forming a photoresist pattern, wet etching the blocking layer under the photoresist pattern using the photoresist pattern as a mask to form the blocking pattern, and removing the photoresist pattern by a stripping process It is preferable to include the step of.

In the method of manufacturing a halftone mask for a liquid crystal display according to an exemplary embodiment of the present invention, the forming of the transflective pattern may include coating and exposing a photoresist on the transflective layer and then exposing the exposed photoresist. Developing a resist to form a photoresist pattern; wet etching the semi-transmissive layer under the photoresist pattern with the photoresist pattern as a mask to form the semi-transmissive pattern; and stripping the photoresist It is preferable to include the step of cleaning after removing the pattern.

In the halftone mask for a liquid crystal display according to an exemplary embodiment of the present invention and a method of manufacturing the same, the blocking pattern may be formed of any one material of chromium, nickel, and molybdenum, or may be formed of two or more alloys of chromium, nickel, and molybdenum. It is desirable to make.

In the halftone mask for a liquid crystal display device and a method of manufacturing the same according to an embodiment of the present invention, the transmittance of the transflective pattern is preferably 30% to 50% of the transmittance of the transmissive region.

In the halftone mask for a liquid crystal display according to an exemplary embodiment of the present invention and a method for manufacturing the same, the transflective pattern is preferably made of chromium oxide.

Specific details of other embodiments are included in the detailed description and the drawings. Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. Like reference numerals refer to like elements throughout.

Hereinafter, a halftone mask for a liquid crystal display and a method of manufacturing the same according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

5 is a schematic cross-sectional view of a halftone mask for a liquid crystal display according to an exemplary embodiment of the present invention.

Referring to FIG. 5, in the halftone mask for a liquid crystal display according to the exemplary embodiment, only the blocking region S and the semi-transmissive pattern 120 are formed to block the incident light by forming the blocking pattern 110. Transmissive region (H / T) that transmits a part of incident light, no blocking pattern 110 or transflective pattern 120 is formed, and only transparent substrate 100 exists and transmits region (T) that transmits almost all of incident light. Divided by).

Here, the transparent substrate 100 is made of quartz (Quartz), the blocking pattern 120 is deposited with an opaque metal having a low reflectance such as chromium (Cr), nickel (Ni), molybdenum (Mo) or alloys thereof do.

In the case of the semi-transmissive pattern 120, a semi-transmissive film in which a material such as chromium oxide (CrOx) is deposited is formed of a material having a transmittance characteristic of about 40%, that is, about 30% to 50% of incident light. The thickness of the residual photoresist PR can be controlled using the semi-transmissive layer while giving a difference in exposure time.

In the conventional halftone mask, the overlay accuracy of the blocking pattern and the semi-transmissive pattern and the etching selectivity of the double layer forming the patterns become a problem. In order to solve the problem, the blocking pattern 110 is formed on one surface of the transparent substrate 100. On the other side, the transflective pattern 120 is formed to form the entire pattern.

In such a structure, since the blocking pattern 110 and the transflective pattern 120 are formed on different surfaces and are not related at all during etching, there is no need to consider the etching selectivity. In addition, when the two patterns overlap by forming both the blocking pattern and the transflective pattern on one side, a high level of overlay accuracy is required at the boundary, but in the present invention, the two patterns 110 and 120 are formed on different surfaces. This problem can be improved.

That is, in the related art, the height of the transflective pattern is changed for each region at the boundary where the transflective pattern overlaps the blocking pattern (the portion where the transflective pattern and the blocking pattern overlap and only the transflective pattern is formed), and thus the light transmittance Since this is different, in order to minimize this problem, the overlay accuracy has to be implemented at a high level. On the other hand, according to the present invention, as can be seen in L1 and L2 of Figure 5, regardless of the position of the light transmittance on the semi-transmissive region (H / T) is the same, so the overlay accuracy or etching selectivity Regardless, even in an area corresponding to the boundary of the blocking pattern 110 or the transflective pattern 120, an improved profile characteristic such as R3 may be implemented.

When the transparent insulating substrate 200 coated with the photoresist PR is exposed and developed, as shown in FIG. 5, the height of the photoresist PR under the blocking region S and the transflective region H are shown. The height of the photoresist PR positioned under the / T) is different from each other, and the photoresist PR under the transmission region T is completely removed.

6 and 7 are graphs showing transmission characteristics and exposure states of the halftone mask of FIG. 5, respectively.

6 and 7, since the blocking region S blocked from light by the blocking pattern 110 has a light transmittance of 0%, exposure of the photoresist PR coated on the transparent insulating substrate 200 is performed. The rate is 0%.

On the other hand, since the transmittance of light T is close to 100%, the photoresist PR formed under the transmission area T is exposed to nearly 100%, and the photoresist PR in this state is developed. When developed in a developer, the transparent insulating substrate 200 of the lower layer is exposed to a predetermined width.

Since the transflective region H / T has a light transmittance of about 40%, the photoresist PR is exposed only to a partial height and then removed by the developing process.

If a halftone mask having such exposure characteristics is applied to a mask process, etching may be performed at different heights during the same process time.

8 is a flowchart illustrating a method of manufacturing a halftone mask for a liquid crystal display according to an exemplary embodiment of the present invention, and FIGS. 9A to 9I illustrate a method of manufacturing a halftone mask for a liquid crystal display according to an exemplary embodiment of the present invention. It is sectional drawing by process for demonstrating this.

A method of manufacturing a halftone mask for a liquid crystal display according to an exemplary embodiment of the present invention includes a deposition step S100 of a blocking layer 111, a forming step S110 of a blocking pattern 110, and a transflective layer 121. The deposition step (S120), the semi-transmissive pattern 120 is formed of a step (S130).

This process will be described in more detail with reference to FIGS. 9A to 9I as follows.

First, in step S100, the blocking layer 111 and the photoresist are sequentially formed on one surface of the transparent substrate 100 (FIG. 9A).

Next, in step S111, the photoresist is patterned by exposure and development to form a photoresist pattern 130 (FIG. 9B). In step S112, the lower blocking layer 111 is formed by using the photoresist pattern 130 as a mask. ) Is wet-etched to expose a portion of the transparent substrate 100 to form a blocking pattern 110 (FIG. 9C).

Next, in step S113, the photoresist pattern 130 is removed by stripping and cleaning (FIG. 9D). In step S114, the protective layer 140 is formed on the entire surface of the transparent substrate 100 on which the blocking pattern 110 is formed. ) (FIG. 9E). The passivation layer 140 is configured to cover the blocking pattern 110 to protect the blocking pattern 110 from an etchant in a wet process for forming the transflective pattern 120.

Next, in step S120, the semi-transmissive layer 121 is laminated on the other surface of the transparent substrate 100 on which the blocking pattern 110 and the protective layer 140 are not formed (FIG. 9F).

Next, in step S131, the photoresist is coated on the entire surface, and then the photoresist is patterned by exposure and development to form a photoresist pattern 131 (FIG. 9G). In operation S132, the semi-transmissive layer 121 is wet-etched using the photoresist pattern 131 as a mask to form a semi-transmissive pattern 120, and then the remaining photoresist pattern 131 is stripped. It washes (FIG. 9H).

Next, in step S133, by removing the protective layer 140 on the blocking pattern 110, a half-tone mask is formed on one surface, the semi-transmissive pattern 120 is formed on the other surface (FIG. 9I).

As such, the blocking pattern 110 is formed on one surface of the transparent substrate 100 used as mask glass, and the semi-transmissive pattern 120 is formed on the other surface, thereby providing a conventional blocking pattern and a semi-transmissive pattern. It is possible to eliminate the burden of overlay accuracy and etch selectivity for, and improve profile characteristics at the boundary.

Although embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features thereof. I can understand that.

Therefore, since the embodiments described above are provided to completely inform the scope of the invention to those skilled in the art, it should be understood that they are exemplary in all respects and not limited. The invention is only defined by the scope of the claims.

The halftone mask for a liquid crystal display according to the preferred embodiment of the present invention made as described above improves the profile characteristics of the photoresist in the region corresponding to the boundary portion where the blocking pattern or the transflective pattern is formed, and improves the required level of overlay accuracy. Can be lowered to increase the efficiency of the process.

In addition, the method for manufacturing a halftone mask for a liquid crystal display according to a preferred embodiment of the present invention can efficiently produce such a halftone mask.

Claims (11)

Transparent substrates; A blocking pattern formed in a blocking region of one surface of the transparent substrate; A semi-transmissive pattern formed on the transflective region of the other side of the transparent substrate; And And a transmissive region defined on the transparent substrate except for the blocking region and the transflective region. The method of claim 1, The blocking pattern is, A halftone mask for a liquid crystal display device, which is made of any one of chromium, nickel, molybdenum, or two or more alloys of chromium, nickel, and molybdenum. The method of claim 1, The transmittance of the transflective pattern is 30% to 50% of the transmittance of the transmissive region, wherein the halftone mask for a liquid crystal display device. The method of claim 1, The transflective pattern is, Halftone mask for liquid crystal display device which consists of chromium oxide. Forming a blocking layer on one surface of the transparent substrate; Patterning the blocking layer to form a blocking pattern in a blocking region of the transparent substrate; Forming a transflective layer on the other side of the transparent substrate; And And forming a transflective pattern in the transflective region of the transparent substrate through patterning of the transflective layer to define the transmissive region as the transmissive region except for the blocking region and the transflective region. Method for producing a halftone mask for use. The method of claim 5, After forming the blocking pattern, forming a protective film on the entire surface of the transparent substrate to cover an upper portion of the blocking pattern; And after removing the passivation pattern, removing the protective film. The method of claim 5, Forming the blocking pattern, After coating and exposing the photoresist on the blocking layer, developing the exposed photoresist to form a photoresist pattern; Forming a blocking pattern by wet etching the blocking layer under the photoresist pattern using the photoresist pattern as a mask; And And removing the photoresist pattern by a stripping process and then cleaning the photoresist pattern. The method of claim 5, Forming the transflective pattern, After coating and exposing the photoresist on the transflective layer, developing the exposed photoresist to form a photoresist pattern; Wet etching the transflective layer under the photoresist pattern using the photoresist pattern as a mask to form the transflective pattern; And And removing the photoresist pattern by a stripping process and then cleaning the photoresist pattern. The method of claim 5, The blocking pattern is, A method of manufacturing a halftone mask for a liquid crystal display device, comprising a material of any one of chromium, nickel, and molybdenum, or an alloy of two or more of chromium, nickel, and molybdenum. The method of claim 5, The transmittance of the transflective pattern is It is 30 to 50% of the transmittance | permeability which the said transmission area has, The manufacturing method of the halftone mask for liquid crystal display devices characterized by the above-mentioned. The method of claim 5, The transflective pattern is, A method of manufacturing a halftone mask for a liquid crystal display, characterized in that it is made of chromium oxide.

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