Process for plasma etching of vias in a dielectric layer with removal of residues

摘要

Disclosed is a process for plasma etching a mask patterned dielectric film (10) to form vias (11) on a semiconductor wafer, so that the resulting etched structure is devoid of residues on the walls of the structure. A via (11) is an opening through a dielectric material through which a point of contact of underlying metal (12) with a metal film (14) deposited over the dielectric is made. The underlying metal (12), when exposed to plasma, has a tendency to sputter onto the vertical wall portions of the contact via structures. The metal-containing sputtered material forms a residue that essentially cannot be removed in the subsequent photoresist stripping process typically used in semiconductor manufacturing. The plasma etch process in accordance with the invention enables removal of the sputtered metal by utilizing with the basic dielectric etch gases a gas that reacts with the metal to form volatile compounds which are readily evacuable. $$