The effects of HF/PdCl2 activation on electroless copper film properties

A thin seed layer (usually deposited by PVD or CVD) is essential for the copper electroplating technology in ULSI metallizations. Electroless Cu deposition has been proposed as an alternative to the PVD or CVD Cu seed technology due to its conformal nature. The electroless (EL) Cu technology requires an activation or catalyzation (usually by HF/PdCl2 solution) to initiate the deposition process, This paper reports on the effect of the HF/PdCl2 activation on the electroless Cu film properties. The implications of the HF/PdCl2 activation method on electroless Cu role as seed layer for Cu electroplating are also discussed. Electroless Cu has a very conformal growth on the TiN/Ti substrate; with a deposition rate of 15 nm/min. Prolonged HF/PdCl2 has a negative impact on the Cu (111) texture, roughness and resistivity. The RBS analysis show that only trace amount of Pd is incorporated into the electroless Cu film.