Photoresist composition and method of fabricating thin film transistor substrate

A method of fabricating a thin film transistor (TFT) substrate using a photoresist composition, the method comprising:

• forming a gate electrode on a substrate;
• forming a gate insulating film on the gate electrode;
• forming a semiconductor layer on the gate insulating film;
• forming a source electrode and a drain electrode on the semiconductor layer;
• and
• forming a pixel electrode connected to the drain electrode, wherein at least one of the respective steps comprises a photolithography process, which comprises the steps of:
• forming a layer made of either a conductive material or a non-conductive material;
• forming a composition comprising a binder resin having a novolak resin and a compound represented by the chemical formula (1), a photosensitizer comprising a diazide-based compound, and a solvent;
• forming a photoresist film using the composition;
• forming a photoresist pattern by exposing and developing the photoresist film;
• and
• etching the layer using the photoresist pattern:
• wherein R1-R9 each comprise a hydrogen atom, an alkyl group, or a benzyl group, a is an integer from 0 to 10, b is an integer from 0 to 100, and c is an integer from 0 to 10.