Semiconductor Energy Laboratory Co., Ltd.

Shiori Murayama

Shunpei Yamazaki

Haruyuki Baba

A semiconductor device with high on-state current is provided. The semiconductor device includes a transistor. The transistor includes a first insulator; a first oxide over the first insulator; a second oxide over the first oxide; a third oxide; a first conductor and a second conductor over the second oxide; a second insulator; a third conductor; a fourth insulator over the first conductor and the second conductor; and a third insulator over the fourth insulator. An opening reaching the second oxide is provided in the third insulator and the fourth insulator. The third oxide is positioned to cover an inner wall of the opening. The second insulator is positioned to cover the inner wall of the opening with the third oxide therebetween. The third conductor is positioned to fill the opening with the third oxide and the second insulator therebetween. In the channel length direction of the transistor, an angle formed by a bottom surface of the first insulator and a side surface of the first conductor facing the second conductor is smaller than 90&#xb0;.

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Saitama, Japan

Shiori Murayama