Microelectronics: "Modeling a Copper-deposition System"
Patrik Möller, Mikael Fredenberg, and Peter Wiwen-Nilsson - Replisaurus Technologies AB, Kista, Sweden
A flip-chip eliminates the need for wire bonds between the silicon die and the package. Instead, the final wafer-processing step deposits solder beads on the chip pads, so the die package must itself have pads whose positions line up with those beads. Creating these carrier substrates with photolithography can involve almost as many manufacturing steps as when creating the IC itself.
Finding a way to make flip-chip receptacles presents significant engineering challenges, but Replisaurus Technologies AB (www.replisaurus.com), based in Kista, Sweden, has developed a unique method to overcome them. Their process has some interesting twists and turns that required mathematical modeling to better understand and optimize the patented process. COMSOL and the Chemical Engineering Module, with ready-made interfaces already optimized for electrochemical engineering, were the obvious choice.