1. Field of the Invention
The present invention relates to a printing method for forming a pattern in a liquid crystal display panel, and more particularly, to a method for forming a pattern with uniform thickness on a substrate.
2. Description of the Related Art
A display device, especially, a flat panel display such as a liquid crystal display (LCD) device is driven by an active device such as a thin film transistor provided at each pixel. The driving method is referred as an active matrix driving method. According to the active matrix driving method, the active device is arranged at each pixel to drive the corresponding pixel.
FIG. 1 is a view illustrating an active matrix type LCD device. The LCD device is a TFT LCD device in which a thin film transistor is used as the active device. As illustrated, at each pixel of the TFT LCD device, wherein N×M pixels are arranged horizontally and vertically, a TFT formed at a gate line 4 to which a scan signal is applied from an external driving circuit and a data line 6 to which an image signal is applied is provided. The TFT includes a gate electrode 3 connected to the gate line 4, a semiconductor layer 8 formed on the gate electrode 3 and activated as a scan signal is applied to the gate electrode 3, and a source/drain electrode 5 formed on the semiconductor layer 8. A pixel electrode 10 is formed in a display region of the pixel 1. The pixel electrode 10 is connected to the source/drain electrode 5 and operates liquid crystal (not illustrated) by receiving an image signal through the source/drain electrode 5 as the semiconductor layer 8 is activated.
FIG. 2 is a view illustrating the structure of the TFT arranged at each pixel. As illustrated, the TFT includes a substrate 20 formed of a transparent insulating material such as glass, a gate electrode 3 formed on the substrate 20, a gate insulating layer 22 formed on the entire surface of the substrate 20, a semiconductor layer 8 formed on the gate insulating layer 22 and activated as a signal is applied to the gate electrode 3, a source/drain electrode 5 formed on the semiconductor layer, and a passivation layer 25 formed on the source/drain electrode 5 for protecting the device.
The source/drain electrode 5 of the TFT is electrically connected to a pixel electrode formed in the pixel region, and displays an image by driving liquid crystal as a signal is applied to the pixel electrode through the source/drain electrode 5.
In the active matrix type LCD device, each pixel has a size corresponding to several tens of μm. Accordingly, the active device such as the TFT arranged in the pixel has to be formed to have a minute size corresponding to several μm. Moreover, as the consumer's demand for a display device of a high image quality such as an HDTV is being increased, more pixels have to be arranged on a screen of the same area. Accordingly, an active device pattern arranged in each pixel (including a gate line pattern and a data line pattern) has to be also formed to have a minute size.
In order to fabricate an active device such as a TFT according to the related art, a pattern, a line, and the like of the active device are formed using a photolithographic process using an exposing device. However, the photolithographic process includes a series of processes such as a photoresist deposition, an alignment process, an exposure process, a developing process, a cleaning process, and the like.
Also, the photolithographic process must be repeated several times to form patterns of the liquid crystal display device, thereby lowering productivity.