1. Field of the Invention
The present invention relates to a thin film transistor substrate and a flat panel display apparatus that has uniform electrical characteristics and uniform display characteristics.
2. Description of the Related Art
Recently, many existing display apparatuses are replaced by flat panel display apparatuses that are portable and thin. Of among flat panel display apparatuses, liquid crystal display apparatuses and organic light-emitting display apparatuses appeal most to people because of their excellent image quality and their portability.
Meanwhile, such flat panel display apparatuses include a thin film transistor substrate including a plurality of thin film transistors for driving or controlling pixels. Each of the thin film transistors includes a channel region that is made out of crystalline silicon that has excellent electrical characteristics.
Crystalline silicon may be produced by emitting a laser beam onto amorphous silicon to crystallize the amorphous silicon. During the crystallization process, protrusions are formed on a surface of the crystalline silicon. In particular, when the crystallization process is performed by sequential lateral solidification (SLS), crystals growing in two directions meet to form protrusions.
The protrusions interrupt the flow of current, thereby degrading the electrical characteristics of each of the thin film transistors. Also, the protrusions irregularly distributed on the channel region degrade the uniform electrical characteristics of the thin film transistor substrate, thereby degrading the image quality characteristics of the flat panel display apparatus.