Semiconductor device having stacked oxide semiconductor layers
AssigneeSemiconductor Energy Laboratory Co., Ltd.
InventorShunpei Yamazaki
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Abstract
One embodiment is a method for manufacturing a stacked oxide material, including the steps of forming an oxide component over a base component; forming a first oxide crystal component which grows from a surface toward an inside of the oxide component by heat treatment, and leaving an amorphous component just above a surface of the base component; and stacking a second oxide crystal component over the first oxide crystal component. In particular, the first oxide crystal component and the second oxide crystal component have common c-axes. Same-axis (axial) growth in the case of homo-crystal growth or hetero-crystal growth is caused.
Claims18
A semiconductor device comprising:
- a gate electrode;
- a gate insulating film over the gate electrode;
- a first oxide semiconductor layer over the gate insulating film;
- a second oxide semiconductor layer over the first oxide semiconductor layer;
- a third oxide semiconductor layer over the second oxide semiconductor layer;
- and
- a source electrode and a drain electrode electrically connected to the second oxide semiconductor layer,
- wherein the second oxide semiconductor layer comprises a channel formation region which overlaps with the gate electrode with the first oxide semiconductor layer and the gate insulating film interposed therebetween, and
- wherein the second oxide semiconductor layer comprises crystals which are c-axis-aligned.
A semiconductor device comprising:
- a gate electrode;
- a gate insulating film;
- a first oxide semiconductor layer;
- a second oxide semiconductor layer;
- a third oxide semiconductor layer;
- and
- a source electrode and a drain electrode electrically connected to the second oxide semiconductor layer,
- wherein the second oxide semiconductor layer is between the first oxide semiconductor layer and the third oxide semiconductor layer,
- wherein the second oxide semiconductor layer comprises a channel formation region,
- wherein the gate electrode and the channel formation region overlap with each other with the first oxide semiconductor layer and the gate insulating film interposed therebetween, and
- wherein the second oxide semiconductor layer comprises crystals which are c-axis-aligned.
A semiconductor device comprising:
- a gate electrode;
- a gate insulating film;
- an oxide semiconductor layer comprising a first oxide semiconductor layer, a second oxide semiconductor layer over the first oxide semiconductor layer, and a third oxide semiconductor layer over the second oxide semiconductor layer;
- and
- a source electrode and a drain electrode electrically connected to the oxide semiconductor layer,
- wherein a relation of Ec−Ef<Eg/2 is satisfied where Ec is an energy at a bottom of a conduction band of the oxide semiconductor layer, Ef is a Fermi energy of the oxide semiconductor layer, and Eg is a band gap of the oxide semiconductor layer,
- wherein the second oxide semiconductor layer comprises a channel formation region,
- wherein the channel formation region and the gate electrode overlap with each other with the gate insulating film and the first oxide semiconductor layer interposed therebetween, and
- wherein the second oxide semiconductor layer comprises crystals which are c-axis-aligned.
Dependencies are inferred from the claim text.