Thin film transistor device (TFT) comprising stacked oxide semiconductor layers and having a surrounded channel structure

摘要

A semiconductor device having stable electric characteristics is provided. The transistor includes first to third oxide semiconductor layers, a gate electrode, and a gate insulating layer. The second oxide semiconductor layer has a portion positioned between the first and third oxide semiconductor layers. The gate insulating layer has a region in contact with a top surface of the third oxide semiconductor layer. The gate electrode overlaps with a top surface of the portion with the gate insulating layer positioned therebetween. The gate electrode faces a side surface of the portion in a channel width direction with the gate insulating layer positioned therebetween. The second oxide semiconductor layer includes a region having a thickness greater than or equal to 2 nm and less than 8 nm. The length in the channel width direction of the second oxide semiconductor layer is less than 60 nm.

主权项

1. A transistor comprising:
a first oxide semiconductor layer; a second oxide semiconductor layer over the first oxide semiconductor layer; a third oxide semiconductor layer over the second oxide semiconductor layer; a gate insulating layer over and in contact with the third oxide semiconductor layer; and a gate electrode over the gate insulating layer; wherein a portion of the gate electrode faces a side surface of the second oxide semiconductor layer in a channel width direction with the gate insulating layer positioned therebetween, wherein the portion of the gate electrode extends below a bottom surface of the second oxide semiconductor layer in a depth direction, wherein the second oxide semiconductor layer includes a region having a thickness greater than or equal to 2 nm and less than 8 nm, and wherein a length of the second oxide semiconductor layer in a channel width direction is less than 60 nm.