Local crystallization by heat treatment

An apparatus comprising:

• a crystallization apparatus for crystallizing a semiconductor layer, the crystallization apparatus having:
• at least one heat emission part configured to emit heat;
• an electrical network arranged in a cylindrical configuration, the electrical network including a first power line and a second power line connected to a separate power source from the first power line;
• a support part that supports the heat emission part;
• and
• a roller that receives the heat emission part and comprises at least one opening that is aligned with the heat emission part and that is sized to correspond to the semiconductor layer of a thin film transistor,
• wherein the heat emission part is connected between the first power line and the second power line to receive power from the first power line and the second power line.