Patent ID: 11955430
Assignee: TAIWAN SEMICONDUCTOR MANUFACTURING COMPANY LTD.
Field: Semiconductors (Electrical engineering)
Classification: CPC H | IPC H

Claim 8:
9. A method of manufacturing a semiconductor device, comprising:
forming a first dielectric layer over a substrate;
forming a cobalt plug in the first dielectric layer;
forming a nitride based etch stop layer on the first dielectric layer and the cobalt plug;
forming a second dielectric layer over the nitride based etch stop layer;
forming an opening in the second dielectric layer and the nitride based etch stop layer to expose an upper surface of the cobalt plug;
performing an etching operation using a fluoride containing gas to (1) remove one or more layers of an oxide of cobalt that is formed at or below the upper surface of the cobalt plug and (2) remove portions of the cobalt plug below the one or more layers of the oxide to extend the opening into the cobalt plug;
performing a defluorination process to remove the fluoride containing gas after the opening has been extended a desired distance into the cobalt plug;
forming a recess in the cobalt plug at a bottom of the opening, wherein the recess is spaced from the nitride based etch stop layer; and
forming a tungsten plug in the recess and the opening.