Post-plating Annealing of Light Induced Plated Copper Fingers: Implications for Reliable Metallization

Light-induced plating (LIP)of Ni/Cu presents a potentially lower-cost alternative to screen-printed Ag for silicon solar cell metallization. This paper presents results of self-annealing and post-plating rapid thermal processing (RTP) of plated Cu finger microstructure, texture and resistance. It is shown that the plated Cu conductors, if not thermally-annealed immediately after plating, self-anneal with time resulting in grain growth and increased (200) to (111) grain texture which occurs with increased tensile stress. Post-plating RTP annealing enables fast annealing and stable Cu fingers with a low ratio of (200) to (111) grain texture. These findings have important implications for plated finger adhesion and highlight the importance of annealing after plating for reliable Cu plated metallization.