Fluorine plasma oxidation of residual sulfur species

Claim 1

An improved method for defining interconnect patterns in semiconductor devices having a titanium-tungsten barrier layer intermediate a silicon substrate and an aluminum conductor layer, said barrier layer being resistant to etching with a fluorine-containing plasma, said method including the steps of: applying a positive photoresist layer including active sulfur species over the aluminum; patterning the photoresist layer to define the desired interconnect pattern; etching the aluminum layer in the pattern defined by the photoresist layer; stripping the remaining photoresist layer using an oxygen plasma whereby residual sulfur species are left on the aluminum; and etching the titanium-tungsten layer in the pattern defined by the photoresist and aluminum layers with a liquid oxidant; wherein the improvement comprises exposing the semiconductor device to a fluorine-containing plasma to remove said residual sulfur species without substantially affecting the titanium-tungsten barrier layer prior to etching the titanium-tungsten layer.

Claim 6

A method for removing residual sulfur species resulting from the oxidation of a positive photoresist layer using an oxygen plasma from the surface of a semiconductor device prior to treatment of said device with a liquid oxidant, said method comprising exposing the device to a fluorine-containing plasma so that the sulfur species are oxidized into a gaseous species which is desorbed from the surface.

Claim 7

A method for removing residual sulfur species resulting from the oxidation of a positive photoresist layer using an oxygen plasma from the surface of a semiconductor device prior to treatment of said device with a liquid oxidant, said method comprising exposing the device to a fluorine-containing plasma so that the sulfur species are oxidized into a gaseous species which is desorbed from the surface.