Hardmask removal for copper interconnects with tungsten contacts by chemical mechanical polishing

摘要

The present invention relates generally to forming interconnects over contacts and more particularly, to a method and structure for filling interconnect trenches with a sacrificial filler material before removal of a hard mask layer to protect the liners of the contacts from damage during the removal process. A method is disclosed that may include: filling an opening in a dielectric layer above a contact and a contact liner with a sacrificial filler material, such that the contact liner is completely covered by the sacrificial filler material; removing a hard mask layer used to pattern and form the opening; and removing the sacrificial filler material from the opening selective to the dielectric layer, the contact liner, and the contact to form an interconnect trench.

主权项

1. A method comprising:
forming a dielectric layer on a contact, the contact having a vertical sidewall and a contact liner formed thereon; forming a hard mask layer on the dielectric layer; forming an opening in the hard mask layer and the dielectric layer, such that the contact and the contact liner are exposed; filling the opening with a sacrificial filler material, such that the contact and the contact liner are substantially covered by the sacrificial filler material; removing the hard mask layer and a portion of the sacrificial filler material, such that an upper surface of the sacrificial filler material in the opening is substantially flush with an upper surface of the dielectric layer; and removing the sacrificial filler material from the opening selective to the dielectric layer, the contact liner, and the contact to form an interconnect trench.