Abstract: A method includes forming a first metallic feature, forming a dielectric layer over the first metallic feature, etching the dielectric layer to form an opening, with a top surface of the first metallic feature being exposed through the opening, and performing a first treatment on the top surface of the first metallic feature. The first treatment is performed through the opening, and the first treatment is performed using a first process gas. After the first treatment, a second treatment is performed through the opening, and the second treatment is performed using a second process gas different from the first process gas. A second metallic feature is deposited in the opening.

Abstract: An ammonium fluoride gas may be used to form a protection layer for one or more interlayer dielectric layers, one or more insulating caps, and/or one or more source/drain regions of a semiconductor device during a pre-clean etch process. The protection layer can be formed through an oversupply of nitrogen trifluoride during the pre-clean etch process. The oversupply of nitrogen trifluoride causes an increased formation of ammonium fluoride, which coats the interlayer dielectric layer(s), the insulating cap(s), and/or the source/drain region(s) with a thick protection layer. The protection layer protects the interlayer dielectric layer(s), the insulating cap(s), and/or the source/drain region(s) during the pre-clean process from being etched by fluorine ions formed during the pre-clean process.

Abstract: An ammonium fluoride gas may be used to form a protection layer for one or more interlayer dielectric layers, one or more insulating caps, and/or one or more source/drain regions of a semiconductor device during a pre-clean etch process. The protection layer can be formed through an oversupply of nitrogen trifluoride during the pre-clean etch process. The oversupply of nitrogen trifluoride causes an increased formation of ammonium fluoride, which coats the interlayer dielectric layer(s), the insulating cap(s), and/or the source/drain region(s) with a thick protection layer. The protection layer protects the interlayer dielectric layer(s), the insulating cap(s), and/or the source/drain region(s) during the pre-clean process from being etched by fluorine ions formed during the pre-clean process.