| abstract |
The present invention provides a means for correcting a threshold voltage of a semiconductor device. In a semiconductor device, an inverter circuit 120 includes transistors 121 and 122. At least one transistor includes a base insulating layer 502 over a substrate 500, oxide semiconductor layers 504a and 504b over the base insulating layer 502, a source electrode 506a and a drain electrode 506c over the oxide semiconductor layers 504a and 504b, An oxide semiconductor layer 504c in contact with the electrode 506a and the drain electrode 506c; a gate insulating layer 508 over the oxide semiconductor layer 504c; a gate electrode 510a over the gate insulating layer 508; An oxide insulating layer 512 over the oxide insulating layer 512 and a planarizing film 513 over the oxide insulating layer 512 are provided. [Selection diagram] FIG. |