Patent ID: 7279393

Claim:
A method for manufacturing a trench isolation structure, comprising: forming a hardmask over a substrate; etching a trench in the substrate through the hardmask; forming a liner in the trench, wherein the liner is below a top surface of the substrate; sequentially depositing an interfacial layer directly on the liner within the trench and on the hardmask, the hardmask having a thickness of less than about 100 nm, said interfacial layer having a thickness ranging from about 30 nm to about 90 nm, wherein the interfacial layer is silicon oxynitride; filling the trench with a dielectric material; and removing the dielectric material, the interfacial layer, and the hardmask layer from a surface of the substrate to form an isolation structure, such that a portion of the interfacial layer remains on a portion of the isolation structure and above the top surface of the substrate.