Semiconductor device including active layer of zinc oxide with controlled crystal lattice spacing and manufacturing method thereof

1. A semiconductor device comprising:

a substrate; and

a semiconductor element including an oxide semiconductor thin film layer of zinc oxide, which is formed on the substrate, and at least a portion of which includes (002) lattice planes having a preferred orientation along a direction perpendicular to the substrate and a lattice spacing d 002 of at least 2.619 Å.

2. The semiconductor device according to claim 1 , wherein the entire oxide semiconductor thin film layer includes (002) lattice planes having a preferred orientation along a direction perpendicular to the substrate and a lattice spacing d 002 of at least 2.619 Å.

3. The semiconductor device according to claim 1 , wherein a portion of the oxide semiconductor thin film layer which is in contact with the substrate includes (002) lattice planes having a preferred orientation along a direction perpendicular to the substrate and a lattice spacing d 002 of at least 2.619 Å.

4. The semiconductor device according to claim 1 , wherein the lattice spacing d 002 of the (002) lattice planes of the oxide semiconductor thin film layer is at least 2.625 Å.

5. The semiconductor device according to claim 1 , further comprising an insulating film formed on the oxide semiconductor thin film layer.

6. The semiconductor device according to claim 1 , wherein the semiconductor element comprises a thin film transistor.

7. A semiconductor device comprising:

a substrate;

an oxide semiconductor thin film layer of zinc oxides, which is formed on the substrate, and at least a portion of which includes (002) lattice planes having a preferred orientation along a direction perpendicular to the substrate and a lattice spacing d 002 of at least 2.619 Å; and

contact layers of zinc oxide, which are formed in contact with the oxide semiconductor thin film layer, and at least a portion of each of which includes (002) lattice planes having a preferred orientation along the direction perpendicular to the substrate and a lattice spacing d 002 that is smaller than the lattice spacing d 002 of the (002) lattice planes of the oxide semiconductor thin film layer.

8. The semiconductor device according to claim 7 , wherein the entire oxide semiconductor thin film layer and the entire contact layers include (002) lattice planes having a preferred orientation along a direction perpendicular to the substrate and a lattice spacing d 002 of at least 2.619 Å.

9. The semiconductor device according to claim 7 , wherein a portion of the oxide semiconductor thin film layer which is in contact with the substrate and a portion of the contact layers which is in contact with the substrate include (002) lattice planes having a preferred orientation along a direction perpendicular to the substrate and a lattice spacing d 002 of at least 2.619 Å.

10. The semiconductor device according to claim 7 , wherein the lattice spacing d 002 of the (002) lattice planes of the contact layers is not more than 2.605 Å.

11. The semiconductor device according to claim 7 , wherein the lattice spacing d 002 of the (002) lattice planes of the oxide semiconductor thin film layer is at least 2.625 Å, and the lattice spacing d 002 of the (002) lattice planes of the contact layers is not more than 2.619 Å.

12. The semiconductor device according to claim 11 , wherein the lattice spacing d 002 of the (002) lattice planes of the contact layers is not more than 2.605 Å.

13. The semiconductor device according to claim 7 , further comprising:

a pair of source/drain electrodes electrically coupled to the oxide semiconductor thin film layer via the contact layers;

a gate insulator; and

a gate electrode formed on the gate insulator;

wherein the oxide semiconductor thin film layer, the contact layers, the pair of the source/drain electrodes, the gate insulator, and the gate electrode constitute a thin film transistor.

14. A semiconductor device comprising:

a substrate; and

an oxide semiconductor thin film layer of zinc oxide which is formed on the substrate, and at least a portion of which includes (002) lattice planes having a preferred orientation along a direction perpendicular to the substrate and a lattice spacing d 002 of at least 2.619 Å;

wherein the oxide semiconductor thin film layer includes a first region of intrinsic zinc oxide and second regions of zinc oxide doped with ions acting as donors to zinc oxide, and

wherein the second regions have a lower resistance than a resistance of the first regions.

15. The semiconductor device according to claim 14 , wherein the entire oxide semiconductor thin film layer includes (002) lattice planes having a preferred orientation along a direction perpendicular to the substrate and a lattice spacing d 002 of at least 2.619 Å.

16. The semiconductor device according to claim 14 , wherein a portion of the oxide semiconductor thin film layer which is in contact with the substrate includes (002) lattice planes having a preferred orientation along a direction perpendicular to the substrate and a lattice spacing d 002 of at least 2.619 Å.

17. The semiconductor device according to claim 14 , wherein the lattice spacing d 002 of the (002) lattice planes of the oxide semiconductor thin film layer is at least 2.625 Å.

18. The semiconductor device according to claim 14 , further comprising:

a pair of source/drain electrodes electrically coupled to the second regions of the oxide semiconductor thin film layer;

a gate insulator; and

a gate electrode formed on the gate insulator to lie over the first region of the oxide semiconductor thin film layer via the gate insulator;

wherein the oxide semiconductor thin film layer, the pair of the source/drain electrodes, the gate insulator and the gate electrode constitute a thin film transistor.

19. The semiconductor device according to claim 14 , wherein the ions acting as donors to zinc oxide are obtained by ionizing at least one group III element.