METHOD FOR FORMING INTERCONNECTS ON SEMICONDUCTOR SUBSTRATES AND STRUCTURES FORMED

A method for forming metal interconnect in a semiconductor structure and the structure formed are disclosed. In the method, a seed layer of a first metal is first deposited into an interconnect opening wherein the seed layer has an average grain size of at least 0.0005 mum. The semiconductor structure is then annealed at a temperature sufficient to grow the average grain size in the seed layer to at least the film thickness. A filler layer of a second metal is then deposited to fill the interconnect opening overlaying the seed layer such that the filler layer has an average grain size of larger than 0.0005 mum and comparable to the annealed seed layer. The first metal and the second metal may be the same or different. A commonly used first metal and second metal may be copper. The present invention may further be carried out by depositing a seed layer of a first metal into an interconnect opening at a thickness of at least 0.0005 mum, then depositing a filler layer to fill the interconnect opening on top of the seed layer such that the filler layer of the second metal may have an average grain size larger than 0.0005 mum. The present invention may further be carried out by depositing a seed layer of a first metal into an interconnect opening at a thickness of at least 0.1 mum, annealing said seed layer, removing the top surface of the seed layer, and then depositing a filler layer. The filler layer should have one grain size comparable to the seed layer. The present invention novel method can be utilized to electroplate various metallic materials into interconnect openings, including but not limited to Cu, Au and Ni.