Effect of fabrication conditions on Cu film formation on Al2O3 and AlN substrates by friction stirring

Abstract

The conditions for Cu film formation by friction stirring on Al₂O₃ and AlN substrates were investigated to develop a Cu circuit pattern formation technology. Different consumable tool geometries resulted in different processing interface temperatures, which had a significant effect on Cu film formation. A Cu film was formed effectively on the AlN substrate, which had high thermal conductivity, by heating the substrate at 100 °C. Finite element simulation revealed that when the substrate was heated at 100 °C, the processing interface temperature was 78 °C higher, even with a weak tool pushing force of 0.3 kN. The rod tool roughened the substrate surface more than the pipe tool, and the Cu film was mechanically bonded to the substrate with higher adhesion strength. Friction stirring was confirmed to be an effective tool for Cu circuit pattern formation.