Semiconductor device and method for manufacturing semiconductor device
A semiconductor device with small fluctuations in transistor characteristics can be provided. The semiconductor device includes a first oxide, a second oxide and a third oxide over the first oxide, a first conductor over the second oxide, a second conductor over the third oxide, a fourth oxide over the first oxide and between the second oxide and the third oxide, a first insulator over the fourth oxide, and a third conductor over the first insulator. The first oxide includes a groove in a region not overlapping with the second oxide and the third oxide. The first oxide includes a first layered crystal substantially parallel to the surface where the first oxide is formed. In the groove, the fourth oxide includes a second layered crystal substantially parallel to the surface where the first oxide is formed. A concentration of aluminum atoms at an interface between the first oxide and the fourth oxide and in the vicinity of the interface is less than or equal to 5.0 atomic %.
1. A semiconductor device comprising:
a first oxide;
a second oxide and a third oxide over the first oxide;
a first conductor over the second oxide;
a second conductor over the third oxide;
a fourth oxide over the first oxide and between the second oxide and the third oxide;
a fifth oxide over the fourth oxide,
a first insulator over the fifth oxide; and
a third conductor over the first insulator,
wherein the first oxide comprises a groove in a region not overlapping with the second oxide and the third oxide,
wherein the first oxide comprises a first layered crystal parallel or substantially parallel to a surface where the first oxide is formed,
wherein in the groove, the fourth oxide comprises a second layered crystal parallel or substantially parallel to the surface where the first oxide is formed,
wherein at least one of a concentration of aluminum atoms at an interface between the first oxide and the fourth oxide and a concentration of aluminum atoms in a region adjacent to the interface is less than or equal to 2.0 atomic %, and
wherein a difference between a level at an interface between the first oxide and the second oxide and a level at an interface between the fourth oxide and the fifth oxide is smaller than a thickness of the fourth oxide.
2. A semiconductor device comprising:
a first oxide;
a second oxide and a third oxide over the first oxide;
a first conductor over the second oxide;
a second conductor over the third oxide;
a fourth oxide over the first oxide and between the second oxide and the third oxide;
a fifth oxide over the fourth oxide;
a first insulator over the fifth oxide; and
a third conductor over the first insulator,
wherein the first oxide comprises a groove in a region not overlapping with the second oxide and the third oxide,
wherein the first oxide comprises a first layered crystal parallel or substantially parallel to a surface where the first oxide is formed,
wherein in the groove, the fourth oxide comprises a second layered crystal parallel or substantially parallel to the surface where the first oxide is formed,
wherein on a side wall of the groove, an a-b plane of the first layered crystal and an a-b plane of the second layered crystal are continuously connected, and
wherein at least one of a concentration of aluminum atoms at an interface between the first oxide and the fourth oxide and a concentration of aluminum atoms in a region adjacent to the interface is less than or equal to 2.0 atomic %.
3. The semiconductor device according to claim 1 ,
wherein the first layered crystal and the second layered crystal each comprise a c-axis perpendicular or substantially perpendicular to the surface where the first oxide is formed.
4. The semiconductor device according to claim 1 ,
wherein at least one of the first oxide and the fourth oxide comprise a CAAC structure in the region adjacent to a lower edge portion of the first conductor and in the region adjacent to a lower edge portion of the second conductor.
5. The semiconductor device according to claim 2 ,
wherein a difference between a level at an interface between the first oxide and the second oxide and a level at an interface between the fourth oxide and the fifth oxide is smaller than a thickness of the fourth oxide.
6. The semiconductor device according to claim 2 ,
wherein the first oxide, the fourth oxide, and the fifth oxide each comprise indium, an element M, and zinc,
wherein the element M is at least one of gallium, aluminum, yttrium, and tin,
wherein an atomic ratio of indium to the element M in the first oxide is higher than an atomic ratio of indium to the element M in the fifth oxide, and
wherein an atomic ratio of indium to the element M in the fourth oxide is higher than the atomic ratio of indium to the element M in the fifth oxide.
7. The semiconductor device according to claim 6 ,
wherein the fourth oxide is a metal oxide with a composition of In:Ga:Zn=4:2:3 [atomic ratio] or in a neighborhood of the composition.
8. The semiconductor device according to claim 2 ,
wherein the first layered crystal and the second layered crystal each comprise a c-axis perpendicular or substantially perpendicular to the surface where the first oxide is formed.
9. The semiconductor device according to claim 2 ,
wherein at least one of the first oxide and the fourth oxide comprise a CAAC structure in a region adjacent to a lower edge portion of the first conductor and in a region adjacent to a lower edge portion of the second conductor.
10. A semiconductor device comprising:
a first oxide;
a first conductor and a second conductor over the first oxide;
a second oxide over the first oxide and between the first conductor and the second conductor;
a first insulator over the second oxide; and
a third conductor over the first insulator,
wherein the first oxide comprises a groove in a region not overlapping with the first conductor and the second conductor,
wherein the first oxide comprises a first layered crystal parallel or substantially parallel to a surface where the first oxide is formed,
wherein in the groove, the second oxide comprises a second layered crystal parallel or substantially parallel to the surface where the first oxide is formed,
wherein on a side wall of the groove, an a-b plane of the first layered crystal and an a-b plane of the second layered crystal are continuously connected, and
wherein at least one of a concentration of aluminum atoms at an interface between the first oxide and the second oxide and a concentration of aluminum atoms in a region adjacent to the interface is less than or equal to 2.0 atomic%.
11. The semiconductor device according to claim 10 ,
wherein the first oxide and the second oxide each comprise indium, an element M, and zinc, and
wherein the element M is at least one of gallium, aluminum, yttrium, and tin.
12. The semiconductor device according to claim 11 ,
wherein the second oxide is a metal oxide with a composition of In:Ga:Zn=4:2:3 [atomic ratio] or in a neighborhood of the composition.
13. The semiconductor device according to claim 10 ,
wherein the first layered crystal and the second layered crystal each comprise a c-axis perpendicular or substantially perpendicular to the surface where the first oxide is formed.
14. The semiconductor device according to claim 10 ,
wherein at least one of the first oxide and the second oxide comprise a CAAC structure in a region adjacent to a lower edge portion of the first conductor and in a region adjacent to a lower edge portion of the second conductor.