Method of controlling contact hole profile for metal fill-in

摘要

A method of eliminating overhang in a contact hole formed in a contact film stack is described. A liner layer is overlaid on the contact film stack, the liner also coating the contact hole. A portion of the liner is removed to expose the overhang, and the exposed overhang is removed. The liner is also used to fill-in a bowing profile of the contact hole, thereby rendering sidewalls of the contact hole smooth and straight suitable for metal fill-in while suppressing piping defects.

主权项

1. A method of removing an overhang from an opening of a contact hole formed through a contact film stack of integrated circuit material, comprising:
forming a contact film stack on a silicon substrate using a plurality of layers of dielectric material; forming a contact hole in the contact film stack on the silicon substrate; coating a surface of the contact film stack and an interior of the contact hole with liner material; removing the liner material to expose an overhang of at least one of the plurality of layers of dielectric material, wherein removing the liner material to expose the overhang comprises exposing the overhang in an outer layer of the contact film stack by removing the liner material from the outer layer while retaining at least portions of the liner material in one or more inner layers of the contact film stack; selectively removing the retained portions of the liner material from the one or more inner layers of the contact film stack while retaining a portion of the liner material in a bowing profile region of an inner layer of the contact film stack; and removing the overhang.