forming the first barrier layer 10 of the present invention any of various refractory metals can be employed such as tantalum tungsten molybdenum hafnium niobium rhenium osmium ruthenium zirconium titanium vanadium chromium and manganese it has been found particularly advantageous to employ alloys of ta or w with n or with certain polyimides especially those formed from the ester of zr ti or hf in fig4 the third dielectric layer 3 is removed utilizing an etchant such as hot phosphoric acid h 3 po 4 at a temperature of about 180 u00b0 c and at a etch rate of about 80 a min that has a negligible attack on the second dielectric layer 5 thus removing the unwanted plating layer 11 from where it was deposited on the third dielectric layer 3 and leaving plating layer 11 extending into the opening 2 up to the top of the second dielectric layer 5 referring to fig5 a metal layer 13 is next electrolessly plated in opening 2 to a thickness which causes the metal layer 13 to extend to about the level of the top surface of the first dielectric layer 7 electroless metal deposition is attractive due to low processing costs and high quality.