Investigation of Ta, TaN and TaSiN barriers for copper interconnects

The effects of Ta, TaN, and TaSiN barrier materials on Cu seed layers and subsequent electroplating were investigated. Significant agglomeration of the Cu seed on damascene trench sidewalls was observed after annealing of the seed deposited on Ta and TaN barriers. With TaSiN, a relatively smooth and continuous Cu seed layer was observed both before and after the anneal. XRD studies indicate that Cu-filled damascene lines with TaSiN barriers have the least stress and the strongest (111) texture as compared to Cu-filled lines with Ta and TaN barriers.