Semiconductor device having a discontinued part between a first insulating film and a second insulating film

1. A semiconductor device comprising:

a first wiring layer and a second wiring layer that are adjacent to each other with a space therebetween;

a first insulating film that comes in contact with one of lower surfaces and upper surfaces of both the first wiring layer and the second wiring layer; and

a second insulating film that comes in contact with the first insulating film as well as side surfaces of both the first wiring layer and the second wiring layer,

wherein a discontinued part, in which an interface between the first insulating film and the second insulating film is discontinued, is formed between the first wiring layer and the second wiring layer, and at least one of the first insulating film and the second insulating film faces an air gap in the discontinued part.

2. The semiconductor device according to claim 1 ,

wherein the first insulating film comes in contact with the lower surfaces of both the first wiring layer and the second wiring layer.

3. The semiconductor device according to claim 1 ,

wherein the first insulating film comes in contact with the upper surfaces of both the first wiring layer and the second wiring layer.

4. The semiconductor device according to claim 1 ,

wherein a trench is formed in the first insulating film, and the air gap is formed in the trench with the second insulating film blocking the trench.

5. The semiconductor device according to claim 1 , further comprising a third insulating film formed over the second insulating film,

wherein a trench is formed in the first insulating film, and the air gap is formed in the trench with the third insulating film blocking the trench.

6. The semiconductor device according to claim 1 ,

wherein the first insulating film and the second insulating film are comprised of respective materials different from each other.

7. The semiconductor device according to claim 6 ,

wherein one of the first insulating film and the second insulating film includes silicon oxide, and the other of them includes silicon nitride.

8. The semiconductor device according to claim 1 ,

wherein the first insulating film and the second insulating film are comprised of the same material as each other.

9. The semiconductor device according to claim 1 , further comprising a dummy wiring layer arranged between the first wiring layer and the second wiring layer,

wherein the discontinued part and the air gap are located between at least one of the first wiring layer and the second wiring layer and the dummy wiring layer.

10. The semiconductor device according to claim 9 ,

wherein the dummy wiring layer surrounds whole circumference of at least one of the first wiring layer and the second wiring layer.

11. The semiconductor device according to claim 1 ,

wherein the air gap surrounds whole circumference of each of the first wiring layer and the second wiring layer.

12. The semiconductor device according to claim 11 ,

wherein the air gap is continuously extended to surround whole circumference of each of the first wiring layer and the second wiring layer.

13. The semiconductor device according to claim 11 ,

wherein the air gap is intermittently extended to surround whole circumference of each of the first wiring layer and the second wiring layer.

14. The semiconductor device according to claim 1 ,

wherein each of the first wiring layer and the second wiring layer is a wiring layer of the uppermost layer.

15. The semiconductor device according to claim 1 ,

wherein the first wiring layer is one transformer that forms a microisolator, and

wherein the second wiring layer is the other transformer that forms the microisolator.