Selective metal etching in metal/polymer structures

A method for selectively removing a metal layer in a structure comprised of a plurality of metal and polymer layers, comprising the steps of:

• positioning said structure in the path of ultraviolet laser pulses, said structure including at least one layer of a metal and one layer of a polymer, irradiating said structure with ultraviolet laser pulses to remove said metal layer without substantial etching of said polymer layer,
• said ultraviolet laser pulses having a wavelength and energy fluence per pulse such that the rate of removal of said metal layer by said laser pulses is at least twice as rapid as the rate of removal of the polymer layer by said laser pulses, for each said laser pulse.

A method for selectively etching a metal layer in the presence of a polymer layer, where said metal layer has a thickness of several microns and said polymer layer also has a thickness of several microns, said polymer being comprised of a material which exhibits an etch depth/pulse versus energy fluence/pulse curve which begins to level off with increasing energy fluence beyond a fluence F=F.sub.0, when said polymer is ablatively photodecomposed by ultraviolet laser pulses having a wavelength in the range 100-400 nm,

• said removal process including the step of applying a single pulse of said ultraviolet radiation, said pulse having an energy fluence sufficiently high to completely remove said metal layer, said fluence being greater than F.sub.0.

A method for removing a copper layer located adjacent to a polyimide layer without substantial removal of said polyimide layer, said method including the steps of applying a number of pulses .ltoreq.5 of ultraviolet radiation to said copper layer, said radiation having a wavelength in the range 100-400 nm and an energy fluence/pulse greater than about 3-5J/cm.sup.2.