Bi-layer hard mask for robust metallization profile

摘要

A robust metallization profile is formed by forming two or more layers of hard mask with different density. Multi-layer metal hard mask is helpful especially in small feature size process, for example, 50 nm and below. Lower layers have higher density. In such ways, enough process window is offered by lower layers and at the same time, round hard mask profile is offered by upper layers.

主权项

1. An integrated circuit (IC) structure comprising:
a substrate, a dielectric layer over the substrate, a first hard mask layer with a first density over the dielectric layer, a second hard mask layer with a second density arranged on the first hard mask layer, and having a rounded upper surface, and an opening extending through the first hard mask layer, the second hard mask layer and the dielectric layer, and a conductive material filling in the opening, wherein the second density of the second hard mask layer is less than the first density of the first hard mask layer.