Printing plate, method of fabricating the same, and method of fabricating flat panel display using the same

A method of fabricating a printing plate includes: preparing a substrate; forming a metal layer on an entire surface of the substrate; forming a resist pattern on the metal layer, the resist pattern having a fine pattern exposing a portion of the metal layer; wet etching the exposed metal layer, and removing the resist pattern to form a metal layer pattern exposing a portion of the substrate; wet etching the exposed substrate, and removing the metal layer pattern to form a recessed  pattern; and forming a compensation layer on an entire surface of the substrate where the recessed  pattern is formed.

This application claims the benefit of priority to Korean Patent Application No. 080558/2005 filed on Aug. 31, 2005, herein incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to a method of fabricating a flat panel display, and more particularly, to a printing plate, a method of fabricating the same, and a method of fabricating a flat panel display using the same, capable of forming fine patterns.

BACKGROUND OF THE INVENTION

With the rapid development of the information society, flat panel displays with favorable characteristics, such as slim profile, lightweight, and low power consumption are increasingly demanded. In addition, fineness and high preciseness are required in interconnections among components of the flat panel device.

Related art interconnections are formed by forming resist patterns using a photolithography or printing method and patterning a conductive layer along the resist patterns. When forming the fine interconnections, it is important to finely form the resist patterns.

At this point, the photolithography process is advantageous to forming the fine resist patterns. In the photolithography process, however, complex processes such as an exposure process and a development process are performed, thus degrading the production efficiency.

Unlike the photolithography process, the printing method has an excellent advantage in terms of production efficiency, but it has a disadvantage in forming a fine pattern.

For example, in the case of a screen printing method, since a resist pattern has a thickness of several ten micrometers, it can form a resist pattern with an excellent corrosion resistance, but it is difficult to form a complicated and fine pattern.

In the case of an offset printing method, a resist pattern is formed by transferring a resist layer on a substrate using a printing plate with a recessedpattern. To form a fine resist pattern, it is important to precisely form the recessedpattern. However, it is difficult to form a printing plate with a fine recessedpattern.

FIG. 1is a photograph illustrating an enlarged section of a region where a recessedpattern is formed in a related art printing plate.

Referring toFIG. 1, when a recessedpattern is formed by wet etching a substrate, a CD-bias of the recessedpattern occurs due to an isotropic etch characteristic of the wet etching, thus increasing the width of the recessedpattern. That is, the width of the recessedpattern increases two times as much as the depth of the recessedpattern.

At this point, if the recessedpattern is formed to have a small depth so as to decrease the width of the recessedpattern, the thickness of the resist pattern becomes small, resulting in a decrease in the corrosion resistance. Therefore, when the interconnections are formed by patterning the conductive layer, it is practically impossible to form the interconnections in a desired pattern.

SUMMARY OF THE INVENTION

The present invention is directed to a printing plate, a method of fabricating the same, and a method of fabricating a flat panel display using the same that substantially obviate one or more problems due to limitations and disadvantages of the related art.

An objective of the present invention is to provide a printing plate and a method of fabricating the same, capable of forming fine patterns having a high precision.

Another objective of the present invention is to provide a method of fabricating a flat panel display with fine patterns having a high precision.

A printing plate is provided. The printing plate comprises a substrate having a recessedpattern and a compensation layer formed on an entire surface of the substrate having the recessedpattern.

In another aspect of the present invention, there is provided a method of fabricating a printing plate. The method comprises preparing a substrate and forming a metal layer on an entire surface of the substrate. The method further includes a step of forming a resist pattern on the metal layer with the resist pattern having a fine pattern exposing a portion of the metal layer. Wet etching the exposed metal layer and removing the resist pattern to form a metal layer pattern exposing a portion of the substrate is then performed, followed by wet etching the exposed substrate and removing the metal layer pattern to form a recessedpattern. Finally the method includes a step of forming a compensation layer on an entire surface of the substrate where the recessedpattern is formed.

In a further aspect of the present invention, there is provided a method of fabricating a flat panel display. The method comprises preparing a substrate and depositing a conductive material on the substrate. The method further includes a step of patterning the deposited conductive material to form a gate electrode and a gate line. The next step is forming a gate insulating layer on an entire surface of the substrate where the gate electrode and the gate line are formed, followed by forming an active layer on the gate insulating layer corresponding to the gate electrode. The method further comprises depositing a conductive material on the active layer, and patterning the deposited conductive material to form source/drain electrodes and a data line, followed by forming a passivation layer on an entire surface of the substrate where the source/drain electrodes and the data line are formed, the passivation layer having a contact hole exposing a portion of the drain electrode. Finally the method includes a step of depositing a conductive material on the passivation layer, and patterning the deposited conductive material to form a pixel electrode such that the conductive layer is electrically connected to the drain electrode, wherein at least one of the gate electrode, the gate line, the active layer, the source/drain electrodes, the data line, the contact hole of the passivation layer, and the pixel electrode is formed by performing a process of forming a resist pattern using a printing plate having a compensation layer formed on an entire surface of the substrate where a recessedportion and a protrudingportion are formed, and performing an etching process on the resulting structure.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 2A to 2Dare sectional views for explaining a printing plate and a method of fabricating the same according to an embodiment of the present invention.

Referring toFIG. 2A, a substrate10is prepared. The substrate10may be formed of material selected from the group consisting of glass, plastic, and metal. A metal layer11is deposited on the substrate10. It is preferable that the metal layer11should have a resistance against an etchant. The reason for this is that the metal layer11will be used as a mask in forming a recessedpattern, which will be described later.

A resist layer is formed on the metal layer11by a typical method and is exposed and developed to form resist patterns12. At this point, predetermined portions A of the metal layer11are exposed by the resist patterns.

Referring toFIG. 2B, the exposed metal layer11is wet etched along the resist patterns12. Then, the resist patterns12are removed and metal layer patterns11′ are formed.

Referring toFIG. 2C, using the metal layer patterns11′ as a mask, the substrate10is wet etched to form recessedpatterns P. Due to an isotropic etch characteristic of the wet etching, both sides of the recessedpattern P are over-etched as much as the depth (h) of the recessedpatterns P. Consequently, the width of the recessedpatterns P increases and thus there is a difficulty in forming a fine interconnection.

Referring toFIG. 2D, the metal layer patterns (11′ inFIG. 2C) are removed. Then, a compensation layer20is formed on an entire surface of the substrate10′ including the recessedpatterns P. In this manner, only the width of the recessedpatterns P can be compensated without changing the shape of the recessedpatterns P.

The compensation layer20may be formed using a chemical vapor deposition (CVD) process or a sputtering process. Examples of the CVD process include a low pressure CVD (LPCVD), an atmospheric pressure CVD (APCVD), and a plasma enhanced CVD (PECVD).

Preferably, the compensation layer20is formed using inorganic-based materials. Examples of the inorganic based materials include silicon nitride, silicon oxide, silicon (Si), chrome (Cr), molybdenum (Mo), aluminum (Al), or copper (Cu).

Preferably, the compensation layer20is formed to have a thickness less than the depth of the recessedpattern P. The reason for this is that the width of the desired recessedpattern P increases as much as the depth (h) of the recessedpattern P. More preferably, the thickness of the compensation layer20meets Eq. (1) below.

where d, h and w represent the thickness of the compensation layer, the depth of the recessedpattern P, and the desired width of the recessedpattern P, respectively.

Therefore, the width of the recessedpattern P is compensated by two times the thickness of the compensation layer20and thus it is possible to fabricate the printing plate with the fine patterns.

A method of fabricating a flat panel display using the printing plate will be described below.

FIGS. 3A to 3Care sectional views illustrating a method of fabricating a flat panel display according to another embodiment of the present invention.

Referring toFIG. 3A, a substrate100is provided. The substrate100may be one of a plastic substrate, a glass substrate, and a metal substrate, but the present invention is not limited to them. A conductive layer is formed by depositing a conductive material for a gate electrode. Then, a first patterning process is performed on the conductive layer to form a gate electrode110and a gate line (not shown).

Referring toFIG. 3B, a gate insulating layer120is formed on an entire surface of the substrate where the gate electrode110and the gate line are formed. The gate insulating layer120may be formed of silicon nitride, silicon oxide, or a stacked layer thereof. The gate insulating layer120may be formed by a CVD process or a sputtering process.

Then, a channel layer131and an ohmic contact layer132are sequentially stacked on the gate insulating layer120corresponding to a gate electrode110. The channel layer131may be formed of amorphous silicon and the ohmic contact layer132may be formed of amorphous silicon with doped N-type or P-type impurities.

A conductive layer is formed by depositing a conductive material for source/drain electrodes on the stacked layer of the channel layer131and the ohmic layer132. Then, a second patterning process is performed on the conductive layer to form source/drain electrodes140aand140band a data line (not shown). Using the source/drain electrodes140aand140bas a mask, the channel layer131and the ohmic contact layer132are patterned to form an active layer130.

In another method of forming the active layer130and the source/drain electrodes140aand140b, the active layer130is formed by patterning the channel layer131and the ohmic contact layer132, the conductive layer is formed by depositing the conductive material for the source/drain electrodes on the active layer130, and then a third patterning process is performed on the source/drain electrodes140aand140band the data line.

Referring toFIG. 3C, a passivation layer150is formed on an entire surface of the substrate where the source/drain electrodes140aand140band the data line are formed. Then, a fourth patterning process is performed such that a predetermined portion of the passivation layer150is etched to form a contact hole exposing a portion of the drain electrode140b. The passivation layer150may be formed of silicon nitride, silicon oxide, acryl based compound, BCB (bensocyclobutene), or PFCB (perfluorocyclobutane).

A conductive layer for a pixel electrode is deposited on the passivation layer150such that its can be electrically connected to the drain electrode140b. Then, a fifth patterning process is performed to form a pixel electrode160. The pixel electrode may be formed of indium tin oxide (ITO) or indium zinc oxide (IZO).

One of the first to fifth patterning processes may be to form the resist pattern using the printing plate of the present invention and etch the resulting structure.

The patterning process using the printing plate of the present invention will be described below in detail with reference toFIGS. 4A to 4D.

Referring toFIG. 4A, a printing plate200is prepared. The printing plate200includes a substrate210and a compensation layer220. The substrate210has recessedpatterns P, and the compensation layer220is formed on an entire surface of the substrate210. The compensation layer220may be formed of inorganic material. The compensation layer220serves to compensate for the width of the recessedpatterns P so as to form a fine pattern.

Meanwhile, a blanket300is provided. A resist layer310is formed on the surface of the blanket300by a general coating method. The general coating method may be one of a spin coating, a dip coating, a spray coating, and a doctor blade, but the present invention is not limited to them.

Referring toFIG. 4B, the resist layer310formed on the surface of the blanket300is transferred on the printing plate200to form a resist pattern310′ on the blanket300. That is, the resist pattern is transferred on a protrudingportion of the printing plate200by rotating the blanket300on the surface of the printing plate200. Therefore, a resist pattern310′ with the recessed portionpattern P is formed on the surface of the blanket300.

Referring toFIG. 4C, a substrate400with the conductive layer410is provided. By rotating the blanket300having the resist pattern310′ on the conductive layer410, the resist pattern310′ is transferred onto the conductive layer410. In this manner, the resist pattern310′ can be finely formed on the conductive layer410.

Although the reverse offset printing method using the printing plate has been described as the method of forming the resist pattern, the present invention is not limited to the reverse offset printing method. That is, another offset printing method using the printing plate can be applied.

Referring toFIG. 4D, a portion of the conductive layer410where the resist pattern310′ is not formed is patterned by wet etching or dry etching. Then, the resist pattern310′ is removed to form the conductive pattern410′.

Although not shown, the flat panel display is fabricated using a general method.

For example, in case where the flat panel display is a liquid crystal display (LCD), a top substrate where a color filter and a transparent electrode are formed is attached to a bottom substrate where a thin film transistor (TFT) is formed and a liquid crystal is then injected.

Also, in case where the flat panel display is an organic electroluminescence display, an organic layer having an emission layer is formed on the pixel electrode and an opposite electrode is formed on the organic layer. The organic layer may further include a charge transport layer or a charge injection layer.

According to the present invention, since the patterning process is performed using the printing plate where the recessed portion is compensated by the compensation layer, the interconnections can be formed more finely and more precisely.

In addition, since the fine and precise interconnections can be easily formed, the flat panel display including the complicated circuits can be easily fabricated.