Trench isolation employing a doped oxide trench fill

1. A method of forming a trench isolation structure in a substrate, said method comprising:

forming at least one opening in a surface of said substrate;

depositing a liner layer at least along a bottom and sidewalls of said opening;

depositing a layer of doped oxide material at least in said opening;

annealing said substrate to reflow said layer of doped oxide material within said opening;

removing, from said layer of doped oxide material located in said opening in said surface of said substance, an about 500 to 1,000 Å thick portion near said surface of said substrate;

depositing an about 500 to 1,000 Å cap layer at least atop a remaining portion of said layer of doped oxide material; and

removing a portion of said cap layer that is atop said surface of said substrate such that said cap layer remains in said opening in said surface of said substrate.

2. The method of claim 1 wherein said substrate comprises a semiconductor material.

3. The method of claim 1 wherein said step of forming an opening includes forming a masking layer on a surface of said substrate, patterning and etching said masking layer to expose portions of said substrate, and etching said exposed portions of said substrate to form said opening in said substrate.

4. The method of claim 1 wherein a depth-to-width aspect ratio of said opening in said substrate is at least 5:1.

5. The method of claim 1 wherein said liner layer comprises a silicon nitride (SiN) layer.

6. The method of claim 1 wherein said liner layer has a thickness of at least 60 Å.

7. The method of claim 1 wherein said layer of doped oxide material is selected from the group consisting of: a borophosphosilicate glass (BPSG), a borosilicate glass (BSG), a phosphosilicate glass (PSG), an arsenic doped glass, or an ion implanted oxide.

8. The method of claim 1 wherein said depositing step deposits a layer of doped oxide material that has a thickness which is at least twice a depth of said trench.

9. The method of claim 1 wherein said annealing step includes reheating said substrate at a temperature of at least 800° C. for at least 10 minutes.

10. The method of claim 1 wherein said step of removing said portion of said layer of doped oxide material includes wet etching said substrate to remove said upper portion of said layer of doped oxide material in said opening.

11. The method of claim 1 wherein said step of removing said portion of said layer of doped oxide material includes removing a further portion of said layer of doped oxide material that is atop said surface of said substrate.

12. The method of claim 1 wherein said step of removing said portion of said layer of doped oxide material includes removing a portion of said liner layer in said opening in said surface of said substrate.

13. The method of claim 1 wherein said step of removing said portion of said layer of doped oxide material includes removing a portion of said liner layer that is atop said surface of said substrate.

14. The method of claim 1 wherein said step of depositing a cap layer includes a high-density plasma (HDP) deposition of a layer of oxide.

15. A method of forming a trench isolation structure in a substrate, said method comprising:

forming at least one opening in a surface of said substrate, said opening in said substrate having a depth-to-width aspect ratio of at least 5:1;

depositing a silicon nitride (SiN) liner layer at least along a bottom and sidewalls of said opening, said SiN liner layer having a thickness of at least 60 Å;

depositing a layer of doped oxide material in said opening;

annealing said substrate at a temperature of at least 800° C. for at least 10 minutes to reflow said layer of doped oxide material within said opening;

removing, from said layer of doped oxide material located in said opening in said surface of said substrate, an about 500 to 1,000 Å thick portion near said surface of said substrate; and

depositing, an about 500 to 1,000 Å thick layer of high-density plasma (HDP) deposited oxide at least atop a remaining portion of said layer of doped oxide material; and

removing a portion of said cap layer that is atop said surface of said substrate such that said cap layer remains in said opening in said surface of said substrate.