Shallow trench isolation chemical-mechanical polishing process

Abstract

A process for fabricating a trench filled with an insulating material in a surface of an integrated circuit substrate is described. One step of the process includes defining a masking layer on a composite layered stack above a region to be protected on the integrated circuit substrate surface. The composite layered stack includes a layer of a first material and a polishing stopping layer. The layer of the first material has a polishing rate by chemical mechanical polishing that is greater than a polishing rate by chemical mechanical polishing of the insulating material. Another step of the process includes etching through the composite layered stack and the integrated circuit substrate to form the trench in the integrated circuit substrate surface and depositing the insulating material on the integrated circuit substrate surface such that the trench is filled with the insulating material. A yet another step of the process includes polishing the integrated circuit substrate surface to remove a substantial portion of the composite layered stack and a portion of the insulating material adjacent to the composite layered stack at about a same rate. The polishing step facilitates in forming a substantially planar surface of the insulating material above the trench and reducing a likelihood of forming of a concave region near a middle region of the surface of the insulating material. The concave region recesses inwardly into the surface of the insulating material in the trench.