process and processing steps are quite similar to that of the semiconductor industry. Deposition, photolithography and etching steps are common to both industries. The key differences are that the TFT is built on a glass substrate instead of a silicon wafer. In addition, the TFT requires a processing temperature ranging from approximately 300 to 500?? compared to about 1,000??required for semiconductor fabrication..

1. PECVD (Plasma Enhanced Chemical Vapor Deposition) Process
Before gas enters the chamber, the state of the vacuum is maintained and the glass plate is heated to a specific temperature. When gas flows into the chamber, the RF voltage is applied from electrodes inside the chamber, which transform gas into a plasma state. From this plasma, precursors are formed and deposited on the glass substrate.

2. Sputtering Process
Sputtering is the process wherein the gas ion, which is the high energy inside the plasma created by RF power or DC power collides with the target surface, resulting in the deposition of the target material on the plate. Generally, the target materials are mounted on the negative electrode surface. Then, the sputtered target materials are deposited on the plate, which is put on the positive electrode. For sputtering, inactive gases are used, such as helium and argon, so that deposition material chemistry is not affected.

3. Photolithography Process
Photolithography is the transfer of a pattern from the photo mask onto a substrate. The photolithography process begins when the substrate is coated with an extremely thin liquid film of photosensitive material, called photoresis. The light then exposes the photoresist, some of which is destroyed when exposed to the light. The unnecessary portion of the material is then cleaned from the surface through another process, leaving an extremely fine pattern behind. Another layer of the photoresist is then deposited to the substrate, exposed, cleaned, until all the layers have been printed or imaged onto the surface. The photolithography process is a critical step within the LCD manufacturing process because panel quality depends on the entire pattern formation. As such, it is extremely sensitive to particles and other forms of contamination. Thus, this process requires a special clean environment, commonly referred to as a clean room, and precise control of equipment, chemicals and materials. In the future, this will prove increasingly important as advanced displays that offer greater functionality and higher performance will require increasingly complex and stringent manufacturing capabilities.

4. Dry etch Process The dry etch process uses reactive species, such as atoms or radicals from the gas plasma, to etch away a portion of the object material. When these species react with the material located on the plate, the open region of material transforms into a volatile state and is removed from the matrix. In this process, the reaction velocity is fast and fine patterns can be formed uniformly.