Semiconductor device and method for fabricating the same

1. A semiconductor device, comprising:

a fin-shaped structure on a substrate;

a gate structure on the fin-shaped structure and an interlayer dielectric (ILD) layer around the gate structure;

a first spacer around and not directly under the gate structure;

a single diffusion break (SDB) structure in the ILD layer and the fin-shaped structure, wherein the SDB structure comprises:

a bottom portion; and

a top portion on the bottom portion, wherein the top portion and the bottom portion comprise different widths and a top surface of the bottom portion is higher than a top surface of the fin-shaped structure; and

a second spacer around the SDB structure, wherein the first spacer and the second spacer comprise same widths and different heights.

2. The semiconductor device of claim 1 , further comprising:

a contact etch stop layer (CESL) between the first spacer and the second spacer.

3. The semiconductor device of claim 2 , wherein the CESL is U-shaped.

4. The semiconductor device of claim 2 , wherein a top surface of the CESL adjacent to the second spacer is lower than a top surface of the CESL adjacent to the first spacer.

5. The semiconductor device of claim 1 , wherein a top surface of the bottom portion is even with a top surface of the gate structure.

6. The semiconductor device of claim 1 , wherein the SDB structure comprises:

a liner; and

a dielectric layer on the liner, wherein the liner and the dielectric layer comprise different material.

7. The semiconductor device of claim 1 , further comprising an air gap in the SDB structure.

8. The semiconductor device of claim 1 , wherein the fin-shaped structure is disposed extending along a first direction and the SDB structure is disposed extending along a second direction.

9. The semiconductor device of claim 8 , wherein the first direction is orthogonal to the second direction.