Patent ID: 11888073
Assignee: SEMICONDUCTOR ENERGY LABORATORY CO., LTD.
Field: Semiconductors (Electrical engineering)
Classification: CPC H | IPC H

Claim 12:
13. A semiconductor device comprising:
a first transistor; and
a second transistor over the first transistor, the second transistor electrically connected to the first transistor,
wherein the first transistor comprises silicon in a channel formation region,
wherein the second transistor comprises:
a first insulating layer;
a first oxide semiconductor layer over the first insulating layer;
a second oxide semiconductor layer over the first oxide semiconductor layer;
a second insulating layer over the second oxide semiconductor layer, the second insulating layer comprising an opening;
a gate electrode, a first part of the gate electrode provided in the opening;
a gate insulating layer located between the second oxide semiconductor layer and the gate electrode; and
a third oxide semiconductor layer located between the second oxide semiconductor layer and the gate insulating layer,

wherein the first insulating layer comprises a first region overlapped with the first oxide semiconductor layer and a second region not overlapped with the first oxide semiconductor layer,
wherein a thickness of the first region of the first insulating layer is larger than a thickness of the second region of the first insulating layer,
wherein, in a cross section parallel to a channel width direction of the second transistor, a second part of the gate electrode does not overlap with the first oxide semiconductor layer and the second oxide semiconductor layer, and
wherein, in the cross section parallel to the channel width direction of the second transistor, a bottom surface of the second part of the gate electrode is located below a bottom surface of the first oxide semiconductor layer.