Manufacturing method of a display device using a two-layered resist

A manufacturing method of a display device comprising:

• a stacked film forming step of forming a stacked film which is a thin film transistor constituting material on an insulating substrate, wherein the stacked film is formed by forming a non-metal multi-layered film by stacking a silicon nitride film which constitutes an insulating layer, an a-Si film which constitutes an activation layer and an n+ a-Si film which constitutes a contact layer in order on the insulating substrate and by stacking a metal film which becomes source and drain electrodes on the non-metal multi-layered film;
• a two-layered resist transfer step of transferring a film-like two-layered resist onto the stacked film, the film-like two layered resist having a five-layered structure which is formed by stacking a cushion layer, an upper-layer resist and a lower-layer resist on a base film in this order and forming a cover film on a topmost surface of the lower-layer resist and sets sensitivity of the upper-layer resist thereof higher than sensitivity of the lower-layer resist;
• a two-layered resist patterning step of exposing the upper-layer resist and the lower-layer resist of the two-layer film-like resist using a half exposure mask and developing the upper-layer resist and the lower-layer resist so as to form predetermined resist patterns on the respective upper-layer resist and lower-layer resist;
• a resist baking step of applying thermal crosslinking to the upper-layer resist and, at the same time, softening the lower-layer resist so as to enhance adhesion property thereof with the stacked film;
• a metal film patterning step of removing the metal film which is exposed from the pattern of the lower-layer resist;
• a non-metal multi-layered film patterning step of removing the non-metal multi-layered film which is exposed from the pattern of the lower-layer resist;
• a lower-layer resist patterning step of removing the lower-layer resist with the pattern of the upper-layer resist by oxygen ashing;
• a channel portion metal film removing step of removing the metal film in a channel portion of the thin film transistor with the pattern of the lower-layer resist thus forming a source electrode and a drain electrode which are separated from each other;
• and
• an n+ a-Si film patterning step of removing a contact film which is exposed in the channel portion metal film removing step.