Iridium Barriers for Direct Copper Electrodeposition in Damascene Processing

Seedless superfilling by copper electrodeposition is demonstrated on submicrometer trenches with Ir barrier layers deposited by atomic layer deposition. The Cu deposition is seen to occur smoothly and continuously on the Ir without the benefit of a copper seed layer. The work supports efforts to develop diffusion barriers compatible with seedless superfill for damascene fabrication of interconnects. It also indicates the suitability of atomic layer deposition for fabrication of barrier layers, in this case Ir, for seedless processing.