A thin-film transistor (TFT) substrate includes a gate electrode, a gate insulation pattern, a channel pattern, a first organic insulation pattern, a source electrode and a drain electrode. The gate electrode is formed on a base substrate. The gate insulation pattern is formed on the gate electrode and is smaller than the gate electrode. The channel pattern is formed on the gate insulation pattern and the channel pattern is smaller than the gate electrode. The first organic insulation pattern is formed on the base substrate to cover the channel pattern, the gate insulation pattern and the gate electrode.