TRANSISTOR

摘要

PROBLEM TO BE SOLVED: To provide a transistor having favorable switching characteristics and high reliability.SOLUTION: For example, a transistor having a bottom gate bottom contact structure is manufactured by a method including: forming a first wiring layer; forming a first insulating film to cover the first wiring layer; forming a semiconductor layer over the first insulating film; forming a conductive film over the semiconductor layer; and performing at least two steps of etching on the conductive film to form second wiring layers which are apart from each other. The two steps of etching include at least a first etching step performed under the condition that at least the etching rate for the conductive film is higher than the etching rate for the semiconductor layer, and a second etching step performed under the condition that the etching rates for the conductive film and the semiconductor layer are higher than the etching rate of the first etching step.