Manufacturing method of TFT array substrate, TFT array substrate and display panel

A manufacturing method of a TFT array substrate comprises:

• providing a rigid substrate, depositing a first metal layer on the rigid substrate, and patterning the first metal layer to form a gate electrode and a gate scanning line;
• depositing sequentially a gate insulating layer, an active layer and a second metal layer on the gate and the gate scanning line;
• coating photoresist on the second metal layer and patterning the photoresist to form a first photoresist layer and a second photoresist layer;
• wherein the first photoresist layer comprises a first-stage photoresist layer, a second-stage photoresist layer and a third-stage photoresist layer;
• the thickness of the second-stage photoresist layer is larger than that of the first-stage photoresist layer, and the thickness of the third-stage photoresist layer is larger than that of the second-stage photoresist layer;
• the first-stage photoresist layer is disposed in the middle of the first photoresist layer and a channel is formed;
• and the thickness of the second photoresist layer is larger than that of the second-stage photoresist layer;
• etching a region of the second metal layer, a region of the active layer and a region of the gate insulating layer, which are outside the channel and uncovered by the first photoresist layer and the second photoresist layer to expose the rigid substrate;
• performing ashing treatment on the first photoresist layer and the second photoresist layer to remove the first-stage photoresist layer, and forming a source electrode, and a drain electrode by etching;
• performing ashing treatment on the second-stage photoresist layer, the third-stage photoresist layer and the second photoresist layer to remove the second-stage photoresist layer, and then depositing a passivation layer as a whole;
• stripping the third-stage photoresist layer and the second photoresist layer, and depositing a transparent conductive layer and patterning the transparent conductive layer to form a pixel electrode and a common electrode.