Modification of Ta/polymeric low-k interface by electron beam treatment

Abstract

Polymeric dielectric, porous polyarylene ether (PAE), was introduced in the Cu damascene structures because of its low dielectric

constant to reduce resistance-capacitance (RC) delay. One of the requirements of a low-k material includes its good adhesion to the

other interconnect materials. In the present study, the adhesion energy (Gc) of the barrier layer Ta/PAE interface was quantitatively

measured by a four-point bending technique. The obtained Gc value of the pristine Ta/PAE interface was 5.9 ± 1.1 J/m2. If the

PAE was subjected to electron-beam (EB) treatment with low dose (20 μC/cm2) prior to Ta deposition, Gc value increased to

8.1 ± 0.5 J/m2. However, with high-dose (40 μC/cm2) EB treatment, Gc value reduced to 4.0 ± 0.6 J/m2. The adhesion improvement

and degradation induced by low- and high-dose EB were correlated to the increase and reduction of the amount of C–Ta

bonds at the Ta/PAE interface, respectively. The phenomena were further studied by X-ray photoelectron spectroscopy analysis.