Air-gap scheme for BEOL process

摘要

The present disclosure relates a method of forming a back-end-of-the-line (BEOL) metallization layer having an air gap disposed between adjacent metal interconnect features, which provides for an inter-level dielectric material with a low dielectric constant, and an associated apparatus. In some embodiments, the method is performed by forming a metal interconnect layer within a sacrificial dielectric layer overlying a substrate. The sacrificial dielectric layer is removed to form a recess extending between first and second features of the metal interconnect layer. A protective liner is formed onto the sidewalls and bottom surface of the recess, and then a re-distributed ILD layer is deposited within the recess in a manner that forms an air gap at a position between the first and second features of the metal interconnect layer. The air gap reduces the dielectric constant between the first and second features of the metal interconnect layer.

主权项

1. A method for forming a back-end-of-the-line (BEOL) metallization layer, comprising:
forming a metal interconnect layer within a sacrificial dielectric layer overlying a substrate; removing the sacrificial dielectric layer to form a recess extending between first and second features of the metal interconnect layer; forming a protective liner layer onto sidewalls and a bottom surface of the recess; depositing a re-distributed inter-level dielectric (ILD) layer within the recess in a manner that forms an air gap at a position between the first and second features of the metal interconnect layer; wherein the air gap has an upper surface comprising:
a first curve symmetric to a second curve;a first cusp, located at an intersection of the first curve and the second curve, which is arranged below a top of the metal interconnect layer;a second cusp located at a non-differentiable point along the first curve; and wherein the first curve is concave to a plane that intersects the first cusp and the second cusp.