Method for stripping a photo resist on an aluminum alloy

A method for forming an aluminum alloy pattern on a semiconductor substrate, comprising the steps of:

• forming, on a semiconductor substrate having an insulation layer thereon, a layer of aluminum alloy containing copper;
• forming a resist pattern on said aluminum alloy layer to create a resist layer portion and exposed layer portion;
• etching the exposed layer portion using the resist pattern as a mask by reactive ion etching using gas plasma containing chlorine ions in a first reaction chamber to form a patterened layer,
• wherein a residual chlorine component is sputtered by ion bombardment on the resist pattern and on the insulation layer on the semiconductor substrate;
• transferring the substrate to a second reaction chamber without exposing the substrate to an external atmosphere;
• and
• downstream ashing the resist pattern isotropically by exposing the resist pattern to an atmosphere containing only non-ionic species in the second reaction chamber, said atmosphere being created by generating gas plasma from reaction gas including a nitrogen containing compound and oxygen by applying electromagnetic power and directing non-ionic species in said gas plasma into the second reaction chamber;
• wherein the substrate with the patterened layer thereon is maintained between 100° C. and 200° C. during the downstream ashing step to remove the residual chlorine component from the patterned layer and the insulation layer;
• and
• wherein the downstream ashing and removing steps occur without generating aluminum oxide particles on the patterned layer.

A method for forming an aluminum-copper alloy wiring pattern on an insulation layer which is formed on a semiconductor substrate, an entire surface of which substrate is immune to damage from plasma due to the insulation layer, comprising the steps of:

• forming, on the semiconductor substrate, over the insulation layer, a layer chosen to have a thickness of 1-4 μm from an aluminum alloy containing 2-4% copper, forming a resist pattern on said aluminum alloy layer to create a resist layer portion and an exposed layer portion;
• etching the exposed layer portion using the resist pattern as a mask by reactive etching using gas plasma containing chlorine ions to form a patterned layer,
• wherein a residual chlorine component is sputtered by ion bombardment on the resist pattern and on the insulation layer covering the semiconductor substrate, said residual chlorine component including at least one of cuprous chloride, cupric chloride and a mixture of Cu, Cl, Al and C;
• downstream ashing the resist pattern isotropically by exposing the resist pattern to gas plasma containing only non-ionic species from reaction gas containing oxygen to which electromagnetic power has been applied, and from the ionic species of the gas plasma;
• and
• removing the residual chlorine component from the patterned layer and the insulation layer by heating the substrate with the patterned layer thereon in vacuum between 250° C. and 300° C.,
• wherein the reaction gas comprises a nitrogen containing compound and oxygen.