Method of fabricating semiconductor device

Abstract

Aiming at obtaining stable and uniform element isolation characteristics without forming the oxide film liner or the like on the inner wall surface of the isolation trench, and ensuring a sufficient level of adhesiveness of the insulating material filled in the isolation trench, and obtaining uniform and excellent element isolation characteristics and a sufficient level of adhesiveness of the buried insulating material, even when applied to large-diameter semiconductor substrates, a thermal oxide film is formed on the inner wall surface of isolation trenches, and a silicon semiconductor substrate is then annealed using a lamp annealer at a temperature higher than in the process of forming thermal oxide film, typically at 950° C. for a predetermined short time (30 seconds herein, for example), wherein the annealing modifies at least the surficial portion of thermal oxide film to have a further complete and uniform state of oxidation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1D are schematic sectional views sequentially showing process steps of fabricating a semiconductor device of a first embodiment;

FIGS. 2A to 2C are schematic sectional views sequentially showing process steps of fabricating a semiconductor device of a first embodiment;

FIGS. 3A to 3D are schematic sectional views sequentially showing process steps of fabricating a semiconductor device according to a modified example of a first embodiment;

FIGS. 4A to 4C are schematic sectional views sequentially showing process steps of fabricating a semiconductor device according to a modified example of a first embodiment;

FIGS. 5A to 5D are schematic sectional views sequentially showing process steps of fabricating a semiconductor device of a second embodiment;

FIGS. 6A to 6C are schematic sectional views sequentially showing process steps of fabricating a semiconductor device of a second embodiment;

FIGS. 7A to 7D are schematic sectional views sequentially showing process steps of fabricating a semiconductor device according to a modified example of a second embodiment;

FIGS. 8A to 8C are schematic sectional views sequentially showing process steps of fabricating a semiconductor device according to a modified example of a second embodiment;

FIGS. 9A to 9E are schematic sectional views sequentially showing process steps of fabricating a semiconductor device of a third embodiment;

FIGS. 10A to 10C are schematic sectional views sequentially showing process steps of fabricating a semiconductor device of a third embodiment;

FIGS. 11A to 11E are schematic sectional views sequentially showing process steps of fabricating a semiconductor device according to a modified example of a third embodiment;

FIGS. 12A to 12C are schematic sectional views sequentially showing process steps of fabricating a semiconductor device according to a modified example of a third embodiment;

FIGS. 13A to 13E are schematic sectional views sequentially showing process steps of fabricating a semiconductor device of a fourth embodiment;

FIGS. 14A to 14C are schematic sectional views sequentially showing process steps of fabricating a semiconductor device of a fourth embodiment;

FIGS. 15A to 15E are schematic sectional views sequentially showing process steps of fabricating a semiconductor device according to a modified example of a fourth embodiment; and

FIGS. 16A to 16C are schematic sectional views sequentially showing process steps of fabricating a semiconductor device according to a modified example of a fourth embodiment.

Claims

1. A method of fabricating a semiconductor device comprising: forming a trench in a device isolation region of a semiconductor substrate;thermally oxidizing the inner wall surface of said trench;annealing said inner wall surface; andfilling said trench with at least an insulating material.

2. The method of fabricating a semiconductor device according to claim 1, wherein said annealing is carried out for each of said semiconductor substrate using a single-wafer-type annealing apparatus.

3. The method of fabricating a semiconductor device according to claim 2, wherein said heating apparatus is a lamp annealer.

4. The method of fabricating a semiconductor device according to claim 1, wherein said annealing is carried out using a batch-type annealing furnace.

5. The method of fabricating a semiconductor device according to claim 1, wherein said annealing is carried out with an oxygen gas or an oxygen-containing gas.

6. The method of fabricating a semiconductor device according to claim 1, wherein said annealing is carried with a nitrogen gas or a nitrogen-containing gas.

7. The method of fabricating a semiconductor device according to claim 1, further comprising, posterior to said annealing and prior to said thermal oxidation of said inner wall surface, forming a nitride film so as to cover said inner wall surface.

8. The method of fabricating a semiconductor device according to claim 1, wherein said insulating material is an insulating material obtained by high-density plasma process.

9. A method of fabricating a semiconductor device comprising: forming a trench in a device isolation region of a semiconductor substrate;thermally oxidizing the inner wall surface of said trench;subjecting the inner wall surface of said trench to plasma treatment; andfilling said trench with at least an insulating material.

10. The method of fabricating a semiconductor device according to claim 9, wherein said plasma treatment is carried out with an oxygen gas or an oxygen-containing gas.

11. The method of fabricating a semiconductor device according to claim 9, wherein said annealing is carried out with a nitrogen gas or a nitrogen-containing gas.

12. The method of fabricating a semiconductor device according to claim 9, further comprising, posterior to said annealing of said inner wall surface and prior to said thermal oxidation, forming a nitride film so as to cover said inner wall surface.

13. The method of fabricating a semiconductor device according to claim 9, wherein said insulating material is an insulating material obtained by high-density plasma process.

14. A semiconductor device comprising: a semiconductor substrate; andan element isolation structure having, as being formed in a device isolation region of said semiconductor substrate, a trench filled with at least an insulating material;wherein said element isolation structure has an oxide film formed by thermal oxidation of the inner wall surface of said trench, and has a nitride film formed by thermally nitriding or by plasma-nitriding the surface of said oxide film.

15. A semiconductor device comprising: a semiconductor substrate; andan element isolation structure having, as formed in a device isolation region of said semiconductor substrate, a trench filled with at least an insulating material;wherein said element isolation structure has a first oxide film formed by thermal oxidation of the inner wall surface of said trench, has a nitride film covering said inner wall surface while placing said first oxide film thereunder, and has a second oxide film formed by thermal oxidation of, or by plasma-oxidizing the surface of said nitride film.