| abstract |
A semiconductor device including a transistor having stable electric characteristics is provided. First, second, and third insulators are sequentially formed on a first conductor on a semiconductor substrate, and a hard mask having a first opening is formed thereon, and A resist mask having a second opening is formed thereon, a third opening is formed in the third insulator, a fourth opening is formed in the second insulator, the resist mask is removed, and the first mask is removed. A fifth opening is formed in the third to third insulators, a second conductor is formed so as to cover the inner wall and bottom surface of the fifth opening, and a third conductor is formed thereon, Polishing is performed to remove the hard mask, the heights of the upper surfaces of the second and third conductors and the third insulator are made to substantially coincide, an oxide semiconductor is formed thereon, and the second insulation The body is less permeable to hydrogen than the first and third insulators, the second conductor is less permeable to hydrogen than the third conductor, and the second insulator is In the edge of the opening in contact with the second conductor. [Selection] Figure 4 |