TFT-LCD formed with four masking steps

A process for forming a thin film transistor-liquid crystal display (TFT-LCD), comprising steps of:

• providing an insulating substrate;
• forming a transparent electrode layer, a first conductive layer and a first photoresist layer on said insulating substrate;
• using a first mask and photolithography procedure to etch said transparent electrode layer and said first conductive layer for defining a transparent electrode and a gate electrode, and removing said first photoresist layer;
• forming an insulation layer, a semiconductor layer, an etch stopper layer and a second photoresist layer on said insulating substrate and said gate electrode, and using a second mask and photolithography procedure to etch said etch stopper layer and said semiconductor layer for defining an etch stopper and a channel region;
• forming a doped semiconductor layer and a data and connection lines layer, removing said second photoresist layer, and forming a third photoresist layer above said insulating substrate;
• using a third mask and photolithography procedure to etch said data and connection lines layer, said doped semiconductor layer and said insulation layer for defining a data and connection lines region, a source/drain region and a gate insulating region;
• forming a second conductive layer above said insulating substrate, and removing said third photoresist layer for defining a conductive region;
• and
• forming a passivation layer and a fourth photoresist layer above said insulating substrate, using a fourth mask and photolithography procedure to etch said passivation layer, said conductive region and said gate electrode for defining a passivation region and a pixel electrode, and removing said fourth photoresist layer.