Interfacial adhesion of copper-low k interconnects

Adhesion energies of Cu-low k dielectric interfaces, measured with the technique of four-point bending, show a correlation to chemical mechanical polish results. A limit of 5 J/m ² is established, below which thin film delamination and cracking are observed. In general, spin-on polymer dielectrics exhibit better adhesion to barrier films than carbon-doped oxide dielectrics. PVD barriers exhibit better adhesion to low k dielectric films than CVD barriers. Surface treatments of the dielectric film before barrier deposition are found to strongly modulate CVD barrier to spin-on polymer adhesion.