Pattern transcription device and method of fabricating cliche for the same

A pattern transcription apparatus comprises a cliché including a concave portion, a convex portion and a printing stopper, the printing stopper formed in the concave portion; and a blanket, on which a resist material layer is coated, rotatable on the cliché, wherein edges of the printing stopper protruding from the printing stopper to have a height greater than a top surface of the convex portion.

The present application claims the benefit of Korean Patent Application No. 2007-0015264 filed in Korea on Feb. 14, 2007, which is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a pattern transcription device, and more particularly, to a transcription device and a method of fabricating a cliche for the pattern transcription device being capable of forming a fine pattern without damages on the pattern.

2. Discussion of the Related Art

A flat panel display device, such as a liquid crystal display (LCD) device, includes a thin film transistor (TFT) as a switching element in each pixel. A fabricating process of the TFT requires many mask processes including a process of forming a photoresist pattern (PR). The PR pattern has a great effect on characteristics of the TFT. Characteristics of the TFT are the subject of significant research and development. Particularly, significant efforts have been devoted to improve characteristics of the TFT using a fine metal pattern.

Generally, a fabricating process of the PR pattern includes a step of forming a PR layer by coating a photosensitive PR material, a step of exposing the PR layer using a mask and a step of developing the exposed PR layer to form the PR pattern. However, since many process steps for fabricating the PR pattern, which are very complicated, are required to fabricate the TFT, production costs increase and production yield decreases.

To resolve these problems, a method of fabricating a resist pattern using a printing method is suggested.FIGs. 1A to 1Dshow a process of fabricating a resist pattern by a conventional reverse offset method. First, as shown inFIG. 1A, a resist material layer32is coated on an outer surface of a blanket30. The blanket30covers along a circumference of a roller31. The blanket30has a circumference being substantially the same as a length of a substrate, on which a resist pattern is to be formed.

Next, as shown inFIG. 1B, the blanket30, on which the resist material layer32is coated, is rotated on a cliché20on a printing table40. The cliché20includes a plurality of concave portions22and a plurality of convex portions24to resulting in an uneven surface. Each convex portion24is disposed between two adjacent concave portions22. When the roller31is rotated on the cliché20, a concave-counter pattern34is formed on the blanket30and a convex-counter pattern36is formed on the convex portion24because the resist material has a greater adhesive strength to the cliché20than the blanket30. Namely, portions of the resist material layer32corresponding to the convex portion24are transferred on the convex portion24, and the other portions of the resist material layer32corresponding to the concave portion22remain on the blanket30, thereby forming the concave-counter pattern34on the blanket30.

Next, as shown inFIG. 1C, the blanket30including the concave-counter pattern34contacts and is rotated on a process-object layer11disposed on a substrate10. Then, the concave-counter pattern34is transferred on the process-object layer11. By applying UV light to the concave-counter pattern34and hardening it, a resist pattern38is formed on the process-object layer11, as shown inFIG. 1D.

Generally, the blanket30is formed of an elastic material, such as silicon or rubber. Accordingly, when the blanket30is rolled on the cliché20, the blanket30is crushed and contacts a bottom surface of the concave portion22of the cliché20because of it's an elastic property, as shown inFIG. 2A, such that the resist material is partially stuck to the bottom surface of the concave portion22and the desired remained pattern38(ofFIG. 1D) can not be obtained. In addition, when the blanket30is rolled on the cliché20and contacts a board between the concave portion22and the convex portion, the resist material layer32flows into the concave portion22, as shown inFIG. 2B. Consequently, there are some undesired resist patterns on the process-object layer11, as shown inFIG. 2C. These problems are easily caused as the resist pattern38is large in size.

To resolve these problems, it is possible to form the concave portions more deep so as not to contact the blanket with the bottom surface of the concave portions. However, when the concave portion has a greater depth, there are losses on a critical dimension. The concave portion is formed by a wet-etching, which has isotropic properties, using an etchant. The greater depth the concave portion has, the greater width the concave portion has. Namely, the width is proportional to the depth. It is difficult to form a fine pattern with a great width.

SUMMARY OF THE DISCLOSURE

Accordingly, the present invention is directed to a patterning transcription device and method of fabricating a cliché for the same that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.

To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, a pattern transcription apparatus comprises a cliché including a concave portion, a convex portion and a printing stopper, the printing stopper formed in the concave portion; and a blanket, on which a resist material layer is coated, rotatable on the cliché, wherein edges of the printing stopper protruding from the printing stopper to have a height greater than a top surface of the convex portion.

In another aspect of the present disclosure, a method of fabricating a cliché for a pattern transcription apparatus comprises forming a metal pattern on a substrate; etching the substrate using the metal pattern as an etching mask to form a concave portion and a convex portion; and forming a printing stopper in the concave portion, wherein edges of the printing stopper protruding from at least one of the convex portion and the printing stopper.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the embodiments, examples of which are illustrated in the accompanying drawings.

FIG. 3is a perspective cross-sectional view of a cliché according to an embodiment of the present invention. InFIG. 3, a cliché includes a plurality of concave portions122, a plurality of convex portions124between adjacent concave portions122, and a printing stopper126in each of the concave portions122. A top the printing stopper126and a top of the convex portion124make an even surface. Namely, the convex portion124protrudes from a bottom surface of the concave portion122by a thickness of the printing stopper126.

Referring toFIGS. 3 and 4A, the printing stopper126is formed of a material having a surface energy density smaller than that of a blanket130. For example, the printing stopper126is formed of Teflon™. First and second edges128aand128bof the printing stopper126protrudes from the top surface of the printing stopper126. Namely, each of the first and second edges128aand128bhas a height greater from a bottom surface of the cliché120than both the printing stopper126and the convex portion124. Each of the first and second edges128aand128bhas a height from the top surface of the printing stopper126about ½ to about ⅓ of a thickness of a resist material layer132coated on an outer surface of the blanket130. A fine pattern is obtained due to the first and second edges128aand128b. It is explained with reference toFIGS. 4A to 4D.

FIGS. 4A to 4Dshow a process of fabricating a resist pattern by a reverse offset method according to an embodiment of the present invention. First, as shown inFIG. 4A, a blanket130covers along a circumference of a roller131, and a resist material layer132is coated on an outer surface of the blanket130. When the blanket130with roller131is rotated, a resist supplier136supplies a resist material to the outer surface of the blanket130such that the resist material layer132is uniformly formed on the outer surface of the blanket130.

Next, as shown inFIG. 4B, the blanket130, on which the resist material layer132is coated, contacts and is rotated on a cliché120formed on a printing table140. As explained withFIG. 3, the cliché120includes the plurality of concave portions122and the plurality of convex portions124. Each convex portion124is disposed between two concave portions122. Each of the concave portions122corresponds to a pattern that is desired to be formed on a substrate. In addition, the printing stopper126is formed in each concave portion122to prevent the resist material being printed on the concave portions122. The central top surface of the printing stopper126has substantially the same height from a bottom surface of the cliché120as the convex portion124. On the other hand, edges of the printing stopper126protrude from the top surface of the printing stopper126. Namely, the edges of the printing stopper126have a height greater than a top surface of the convex portion124. A material of the blanket130has a surface energy density with a range between 20 mJ/ cm2and 23 mJ/ cm2, while a material of printing stopper126, such as Teflon™, has a surface energy density with a range between 13 mJ/cm2and 18 mJ/cm2. In brief, a material of the printing stopper126has a surface energy density smaller than a material of the blanket130. This means that the resist material is much stickier with respect to the blanket130than the printing stopper126. Namely, the resist material has a first adhesive strength to the blanket130and a second adhesive strength, smaller than the first adhesive strength, to the printing stopper126. Moreover, the resist material has a third adhesive strength to the cliché120. The third adhesive strength is greater than the first and second adhesive strengths. Namely, a surface energy density of the blanket130is greater than that of the printing stopper126and smaller than that of the cliché120. Accordingly, when the blanket130contacts and is rotated on the cliché120, a convex-counter pattern134bis formed on the convex pattern124and a concave-counter pattern134is formed on the blanket130. Namely, since the resist material layer132is much stickier to the cliché120than the blanket130, the resist material layer132on the blanket130is transferred to the convex portions124to form the convex-counter pattern134bon the convex portion124when the resist material layer132contacts the cliché120. However, since the resist material layer132is much stickier to the blanket130than the printing stopper126, the resist material layer132on the blanket130is never transferred to the printing stopper126even if the resist material layer132contacts the cliché120. Accordingly, the concave-counter pattern134is formed on the blanket130.

In this case, as shown inFIG. 5, which is an enlarged view showing an “A” region ofFIG. 4B, the edges128aand128bprotrude from a central top surface of the printing stopper126. The protruding portion of the edges128aand128bhas a height about ½ to about ⅓ of a thickness of the resist material layer132. The edges128aand128bis disposed at boundaries between the concave and convex portions122and124. Due to the edges128aand128b, both the convex-counter pattern134band the concave-counter-pattern134are formed to have a desired fine pattern.

Next, as shown inFIG. 4C, the blanket130having a plurality of concave-counter patterns134contacts and rotated on a process-object layer111to from the plurality of concave-counter patterns134on the process-object layer111on a substrate110. Since the resist material is much stickier to the process-object layer111than the blanket130, the concave-counter patterns134on the blanket130are transferred onto the process-object layer111when the concave-counter patterns134contacts the process-object layer111. Since a circumference of the blanket130is substantially the same as a length of the substrate110, the plurality of concave-counter patterns134on the blanket130are wholly transferred onto the process-object layer111by a single rotation.

Next, the concave-counter patterns134on the process-object layer111is irradiated by UV light and hardened to form resist patterns134a on the process-object layer111.

The process-object layer111may be one of a metal layer, from which metal patterns, e.g., a gate electrode, a source electrode and a data electrode of a thin film transistor (TFT), are formed, and an insulating layer including one of silicon oxide and silicon nitride. The process-object layer111may be etched using the resist patterns138as an etching mask to form the metal patterns or a contact hole in the insulating layer.

As explained above, since the printing stopper126, which is less sticky to the resist material than the blanket130, is formed on the concave portions122of the clicke120, the resist material is never transferred to the concave portions122even if the resist material on the blanket130contacting printing stopper126. Moreover, since the edges128aand128bof the printing stopper126protrude from the central top surface of the printing stopper126, it is prevented the resist material flowing into the concave portion122. Accordingly, a desired concave-counter pattern134is formed on the blanket130without a sticky portion on the printing stopper126. The problem in the related art is improved.

FIGS. 6A to 6Gare cross-sectional views showing a process of fabricating a cliché according to an embodiment of the present disclosure. As shown inFIG. 6A, a metal layer212is formed on a substrate211by depositing at least one metallic material selected from a metal group including molybdenum (Mo), chromium (Cr) and nickel (Ni). Next, as shown inFIG. 6B, a photosensitive material layer214is formed on the metal layer212by depositing a photosensitive material such as photoresist. Next, a mask (not shown) having a transmitting portion and a blocking portion is disposed over the photosensitive material layer214. The transmitting portion has a relatively high transmittance so that light through the transmitting portion can completely change the photosensitive material layer214chemically. The blocking portion shields light completely. Namely, a transmittance of the transmitting portion is greater than that of the blocking portion. When the photosensitive material is a positive type, the blocking portion of the mask corresponds to a position that is desired to form a convex portion, and transmitting portion of the mask corresponds to a position that is desired to form a concave portion. If the photosensitive material is a negative type, locations of the blocking and transmitting portions of the mask are changed into each other. Then, the photosensitive material layer214is exposed through the mask (not shown) and developed to form a photosensitive material pattern216, as shown inFIG. 6C.

Next, as shown inFIG. 6D, the metal layer212(ofFIG. 6C) exposed through the photosensitive material patterns216is etched using the photosensitive material pattern216as an etching mask to form a metal pattern218. The metal pattern218corresponds to the photosensitive material pattern216. And then, the substrate211exposed through the metal patterns218is etched using the metal pattern218as an etching mask to form a plurality of concave portions222. Moreover, since the substrate211is etched to form the plurality of concave portions222, other portions of the substrate211protrude. The protruding portions are defined as a plurality of convex patterns224a. Next, as shown inFIG. 6E, a low surface energy density material layer225is formed on the substrate211including photosensitive material pattern216. The low surface energy density material layer225is formed on both the photosensitive material pattern216and a bottom surface of the concave portions222. The low surface energy density material layer225is formed on not only the bottom surface of the concave portion222but also a side wall of the concave portion222. A height of the low surface energy density material layer225in the side wall from a bottom surface of the substrate211is higher than that in a central top surface. Namely, the side wall of the low surface energy density material layer225has the same height as the convex pattern224a, while the central top surface of the low surface energy density material layer225has a lower height than the convex pattern224a. The low surface energy density material layer225may include Teflon™.

Next, the photosensitive material pattern216and the metal pattern218are removed from the substrate211. The low surface energy density material layer225on the bottom surface of the concave portions222is defined as a printing stopper226, as shown inFIG. 6F.

Next, as shown inFIG. 6G, the convex patterns224a(ofFIG. 6F) is selectively etched. A portion of the convex patterns224aafter being selectively etched is defined as a convex portion224. As a result, a central top surface of the printing stopper has the same height as the convex portion224. While, edges228aand228bof the printing stopper226protrude from both the central top surface of the printing stopper and the convex portion224. The substrate211including the plurality of concave portions222, the plurality of convex portions224and the printing stopper226with the edges228aand228bprotruding from the central top surface of the printing stopper226is called a cliché220.

On other hand, a cliché may be formed without a metal layer212(ofFIG. 6A) to decrease a process time and increase production yield. However, since a photosensitive material layer214(ofFIG. 6B) has a poor adhesive strength to the substrate211(ofFIG. 6A) of glass, it is difficult to obtain a fine pattern without the metal layer212(ofFIG. 6A).

In the present invention, a cliché includes a printing stopper of a low surface energy density material in a concave portion. Moreover, edges of the printing stopper protrude from a top surface of the printing stopper. By these features, desired resist patterns are obtained.