Fin field effect transistor (FinFET) device and method for forming the same

1. A fin field effect transistor (FinFET) device structure, comprising:

a substrate;

an isolation structure formed on the substrate;

a first fin structure extending above the substrate, wherein the first fin structure is along a first direction;

a first transistor formed on the first fin structure, wherein the first transistor comprises:

a first gate dielectric layer conformally formed on the first fin structure; and

a first gate electrode formed on the first gate dielectric layer; and

an inter-layer dielectric (ILD) structure formed adjacent to the first transistor, wherein the first gate electrode is in direct contact with a sidewall of the ILD structure,

wherein the sidewall of the ILD structure has a bottom portion and a top portion in a cross-sectional view, the first gate dielectric layer above the isolation structure is in direct contact with the bottom portion of the sidewall of the ILD structure,

wherein an upper portion of the first fin structure protrudes from the isolation structure.

2. The fin field effect transistor (FinFET) device structure as claimed in claim 1 , wherein the first gate electrode is surrounded by the ILD structure.

3. The fin field effect transistor (FinFET) device structure as claimed in claim 1 , further comprising:

a second transistor formed on a second fin structure, wherein the ILD structure is formed between the first transistor and the second transistor.

4. The fin field effect transistor (FinFET) device structure as claimed in claim 3 , wherein the second transistor comprises a second gate dielectric layer and a second gate electrode, and the first gate electrode and the second gate electrode are formed on opposite sidewalls of the ILD structure.

5. The fin field effect transistor (FinFET) device structure as claimed in claim 1 , wherein the first gate dielectric layer comprises a high-k dielectric layer and a diffusion barrier layer.

6. The fin field effect transistor (FinFET) device structure as claimed in claim 1 , wherein the first gate electrode comprises a work function layer, a block layer and a metal fill layer.

7. The fin field effect transistor (FinFET) device structure as claimed in claim 1 , wherein the first gate dielectric layer does not cover the overall sidewalls of the ILD structure.

8. The fin field effect transistor (FinFET) device structure as claimed in claim 1 , further comprising:

an isolation structure, wherein the first fin structure is embedded in the isolation structure.

9. The fin field effect transistor (FinFET) device structure as claimed in claim 1 , wherein a distance between the sidewall of the ILD structure and a sidewall of the first fin structure is in a range from about 5 nm to about 50 nm.

10. A fin field effect transistor (FinFET) device structure, comprising:

a substrate;

an isolation structure formed on the substrate;

a first fin structure and a second fin structure extending above the substate;

a first transistor formed on the first fin structure, wherein the first transistor comprises:

a first gate dielectric layer formed on a top surface and sidewalls of the first fin structure; and

a first gate electrode formed on the first gate dielectric layer;

a second transistor formed on the second fin structure, wherein the second transistor comprises:

a second gate dielectric layer formed on a top surface and sidewalls of the second fin structure; and

a second gate electrode formed on the second gate dielectric layer; and

an inter-layer dielectric (ILD) structure formed between the the first transistor and the second transistor, wherein the ILD structure is directly sandwiched between the first gate electrode and the second gate electrode, and the first gate dielectric layer above the isolation structure is in direct contact with a bottom portion of the sidewall of the ILD structure,

wherein an upper portion of the first fin structure and an upper portion of the second fin structure protrude from the isolation structure.

11. The fin field effect transistor (FinFET) device structure as claimed in claim 10 , wherein the first transistor is an n-type Metal-Oxide-Semiconductor Field-Effect-Transistor (NMOSFET), and the second transistor is a p-type Metal-Oxide-Semiconductor Field-Effect-Transistor (PMOSFET).

12. The fin field effect transistor (FinFET) device structure as claimed in claim 10 , wherein the first gate dielectric layer and the second gate dielectric layer are made of the same material.

13. The fin field effect transistor (FinFET) device structure as claimed in claim 10 , wherein the first gate electrode and the second gate electrode are made of different materials.

14. The fin field effect transistor (FinFET) device structure as claimed in claim 3 , wherein the first transistor is an n-type Metal-Oxide-Semiconductor Field-Effect-Transistor (NMOSFET), and the second transistor is a p-type Metal-Oxide-Semiconductor Field-Effect-Transistor (PMOSFET).

15. The fin field effect transistor (FinFET) device structure as claimed in claim 10 , wherein the first gate electrode comprises a work function layer, a block layer and a metal fill layer.

16. The fin field effect transistor (FinFET) device structure as claimed in claim 10 , wherein the sidewall of the ILD structure has a bottom portion and a top portion, the first gate dielectric layer covers the bottom portion of the sidewall of the ILD structure, and the first gate electrode covers the top portion of the sidewall of the ILD structure.

17. The fin field effect transistor (FinFET) device structure as claimed in claim 10 , wherein a distance between the sidewall of the ILD structure and a sidewall of the first fin structure is in a range from about 5 nm to about 50 nm.