| abstract |
One of the problems is to simplify the photolithography step by reducing the number of exposure masks and to manufacture a semiconductor device having an oxide semiconductor at low cost and with good productivity. A method of manufacturing a semiconductor device having a reverse staggered thin film transistor having a channel etch structure, wherein the oxide semiconductor film and the conductive film are etched using a mask layer formed by a multi-gradation mask, which is an exposure mask in which transmitted light has a plurality of intensities. Is done. In the etching step, the first etching step uses wet etching by etching liquid, and the second etching step uses dry etching by etching gas. |