Method of fabricating thin film transistor substrate and thin film transistor substrate produced using the same

A method of fabricating a thin film transistor substrate, the method comprising:

• forming a gate wiring on an insulating substrate and forming a gate insulating layer on the gate wiring;
• performing a first hydrogen plasma treatment with respect to the gate insulating layer;
• forming a first active layer with a first thickness at a first deposition rate on the gate insulating layer;
• performing a second hydrogen plasma treatment with respect to the first active layer;
• and
• forming, on the first active layer, a second active layer with a second thickness greater than the first thickness at a second deposition rate greater than the first deposition rate,
• wherein, in the first active layer subjected to the second hvdrogen plasma treatment, a ratio of a number of Si—H bonds to a number of Si—H2 bonds is within a range of about 15:1 to about 30:1 .