| While copper damascene processes currently utilize physically vapor deposited (PVD) Cu seed layers, the continued scaling of interconnect feature sizes in advanced nanoelectronic devices requires the development of a more conformal, controllable Cu seed layer technology for use with electrochemically deposited (ECD) copper interconnects. Atomic layer deposition (ALD) is a promising alternative because of its excellent conformality and precise thickness control capability. In this research, a self-limiting plasma-enhanced ALD (PEALD) Cu process, employing Cu(II) acetylacetonate (Cu(acac)2) and atomic hydrogen, was employed to deposit high quality PEALD Cu films. In addition, substrate surface hydrogen plasma treatments prior to PEALD Cu growth were observed to enhance Cu nucleation, decrease Cu surface roughness, and reduce Cu resistivity. The performance characteristics of ECD/PEALD-grown Cu interconnects were compared with those of a conventional ECD/PVD Cu stack. Finally, void-free electroplated Cu was demonstrated on 60 and 35 nm patterned via structures using both ALD Ru/TaN and conventional PVD Ta/TaN liner/barrier structures coupled with PEALD Cu seed layers. The film properties and resulting integration characteristics suggest that PEALD Cu is a promising approach for advanced seed layer applications in CMOS metallization. |
