. . "As is well known in the prior art, the barrier layer is usually chosen from the refractory metals or their alloys, such as for example, Ta, TaNX, Cr, CrNX, Ti, TiNX, W, WNX, TaSiXNY, TiSiXNY, WSiXNY, and other alloys containing one or more of these materials. [0006] As is still further well known, the requirement of being compatible with electroplating copper is fulfille" . .