1. Field of the Invention
The present invention relates to a flat panel display, and more particularly, to a method and apparatus for patterning a thin film, wherein the method and apparatus is adapted for patterning a thin film substantially without the use of photolithography, in a way that may reduce processing time and minimize pattern deformities.
2. Description of the Related Art
Display device are being emphasized more than ever as important visual information communication media. Traditional display devices include cathode ray tubes or Braun tubes, which make the display devices inconveniently large and heavy.
Various display technologies have been developed toward replacing the cathode ray tube, and thereby making the display smaller and lighter. These include liquid crystal display (LCD), field emission display (FED), plasma display panel (PDP), and electro-luminescence (EL) flat panel display technologies, most of which are put to practical use and are on the market.
With recent improvements to its mass production processes, liquid crystal display technology, in particular, has rapidly been replacing the cathode ray tube devices within many applied fields, since the LCD technology provides for devices that are generally light and thin.
In particular, the active matrix type of liquid crystal display, which drives liquid crystal cells by use of thin film transistors (hereinafter “TFT”), has excellent picture quality and low power consumption and is being developed to larger sizes and higher resolutions as a result of research and development and the securing of mass production technology.
An active matrix type of liquid crystal display, as illustrated in FIG. 1, includes a color filter array substrate 22 and a TFT array substrate 23 bonded together with a liquid crystal layer 15 between them. The liquid crystal display illustrated in FIG. 1 represents a part of the whole effective screen area.
The color filter array substrate 22 has a black matrix (not shown), a color filter 13 and a common electrode 14 formed on the rear surface of an upper glass substrate 12. A polarizer 11 is affixed to the front surface of the upper glass substrate 12. The color filter 13 includes red, green and blue color filters to transmit visible light in a specific wavelength band, thereby enabling color display.
On the front surface of the lower glass substrate 16 of the TFT array substrate 23, data lines 19 and gate lines 18 generally cross one another with TFTs formed at their crossing. A pixel electrode 21 is formed at a cell area defined by the data lines 19 and the gate lines 18 on the front surface of the lower glass substrate 16. The TFT 20 drives the pixel electrode 21 by switching a data transmission path between the data line 19 and the pixel electrode 21 in response to a scan signal from the gate line 18. A polarizer 17 is generally affixed to the rear surface of the TFT array substrate 23.
The liquid crystal layer 15 controls the transmission of light incident through the TFT array substrate 23 to an extent proportional to the electric field applied to the liquid crystal material.
The polarizers 11 and 17 that are respectively affixed to the color filter array substrate 22 and the TFT substrate 23 each transmit light polarized in one direction, and their polarizing directions cross each other for certain LCD modes, such as a 90° TN mode.
An alignment film (not shown) may be formed on the opposite interior surfaces of the color filter array substrate 22 and the array TFT substrate 23.
A typical related art fabricating process for producing the active matrix type of liquid crystal display may be divided into a substrate cleaning process, a substrate patterning process, an alignment forming/rubbing process, a substrate bonding/liquid crystal injection process, a mounting process, an inspection process, and a repair process.
The substrate cleaning process removes impurities contaminating the substrate surface of the liquid crystal display. The substrate patterning process is generally divided into the patterning process of the color filter substrate and the patterning process of the TFT array substrate. The alignment film forming/rubbing process coats an alignment film onto each of the color filter substrate and the TFT array substrate and rubs the alignment film with rubbing cloth. The substrate bonding/liquid crystal injection process bonds the color filter substrate with the TFT array substrate by use of a sealant and injects liquid crystal and spacers through a liquid crystal injection hole, and then seals the liquid crystal injection hole. The mounting process connects a tape carrier package (TCP) to a pad part of the substrate, wherein the TCP has integrated circuits such as a gate drive IC and data drive IC mounted on it. Alternately, the drive integrated circuit can be mounted to the substrate directly by using chip-on-glass (COG) technology. The inspection process generally includes an electrical inspection conducted after the data lines, the gate lines, and the pixel electrodes are formed on the TFT array substrate. An electrical inspection and a naked-eye inspection may be conducted after the substrate bonding/liquid crystal injection process. The repair process conducts restoration for those substrates that are judged to be repairable by the inspection process. A substrate that is judged to be un-repairable in the inspection process is discarded.
Generally, a photolithography process is used to pattern thin film materials making up display devices discussed above. The photolithography process includes the coating of photo-resist, mask alignment, exposure, development, and cleaning. However, there is a problem in that the required time for the process is long, the photo-resist material and stripping solution is generally wasteful, and expensive equipment such as exposure equipment is required.