Method for manufacturing thin film transistor and method for manufacturing display device

A method for manufacturing a display device, comprising the steps of:

• stacking a light-blocking film, a base film, a first conductive film, a first insulating film, a semiconductor film, an impurity semiconductor film, and a second conductive film in this order;
• forming a first resist mask having a depressed portion over the second conductive film;
• performing a first etching on the second conductive film, the impurity semiconductor film, the semiconductor film, the first insulating film, the first conductive film, the base film, and the light-blocking film using the first resist mask;
• performing a second etching in which part of the first conductive film is side-etched to form a gate electrode layer of a thin film transistor;
• making the first resist mask reduce to expose a part of the second conductive film, which corresponds to the depressed portion of the first resist mask, and to form a second resist mask;
• completing the thin film transistor in a manner in which a third etching is performed on the second conductive film, the impurity semiconductor film, and part of the semiconductor film using the second resist mask to form a source and drain electrode layer in the second conductive film, a source and drain region in the impurity semiconductor film, and a semiconductor layer in the semiconductor film;
• removing the second resist mask;
• forming a second insulating film so as to cover the thin film transistor;
• forming an opening portion in the second insulating film so that part of the source and drain electrode layer is exposed;
• and
• selectively forming a pixel electrode layer, thereby forming a pixel electrode over the opening portion and the second insulating film and electrically connecting a portion a the second conductive film to a portion of the second conductive film.

A method for fabricating a thin-film structure comprising the steps of:

• forming a first stack of thin films;
• forming a second stack of thin films over the first stack;
• forming a first mask according to a first pattern over the second stack;
• performing a first etching through the first stack and the second stack using the first mask to reproduce the first pattern in the first stack and the second stack;
• performing a second etching in which part of a first thin film of the first stack is side-etched to pattern the first thin film according to a second pattern derived but distinct from the first pattern;
• forming a second mask according to a third pattern over the second stack;
• performing a third etching on at least some of the thin films of the second stack using the second mask to pattern the at least some of the thin films of the second stack according to a third pattern.