lecturer was wrong when he explained why intially Al rather than Cu was used for interconnection. For Cu, people couldn't find effective dry etching to form volatile substance to remove unwanted Cu and form metal lines/patterns, and that is why Cu hadn't been used until CMP technlogy arrived. now Cu is polished away rather than etching away. pattern is formed by etching of dielectric layer and subsequent Cu e-plating - damascene process.
lecturer was wrong when he explained why intially Al rather than Cu was used for interconnection. For Cu, people couldn't find effective dry etching to form volatile substance to remove unwanted Cu and form metal lines/patterns, and that is why Cu hadn't been used until CMP technlogy arrived. now Cu is polished away rather than etching away. pattern is formed by etching of dielectric layer and subsequent Cu e-plating - damascene process.
l880126 11 months ago