Thermal stability and adhesion improvement of Ag deposited on Pa-n by oxygen plasma treatment

Parylene-n (Pa-n) and silver are being studied for ultralarge scale integra ted circuits because of their favorable properties. These include low diele ctric constant (2.65), negligible water take-up, chemical inertness, low te mperature deposition, as well as compatibility with current integrated circ uits manufacturing for Pa-n and the low resistivity (1.6 mu Omega cm), high electromigration resistance for silver. To meet integration requirements, Pa-n and Ag are studied to understand specific reliability issues, e.g., di ffusion, delamination, or loss of adhesion, compatibility, etc. Initial mea surements of silver and dielectric Pa-n were done using four-point probe. T hermal stability and texturing of Ag films on Pa-n? were confirmed using x- ray diffraction analysis. The change associated with resistivity of Ag film s on Pa-l? sample supports the changes observed in x-ray spectra. Rutherfor d backscattering spectrometry and secondary ion mass spectroscopy analysis show insignificant diffusion of Ag in Pa-n. Adhesion analysis of Ag/Pa-n an d Pa-n/Si was done using scratch and tape tests. Oxygen plasma surface trea tment of Pa-n shows drastic improvement of adhesion between Ag and Pa-n wit hout loss of thermal stability of the system. The improvement in adhesion i s associated with increased roughness of Pa-n surface after plasma treatmen t. (C) 2000 American Vacuum Society. [S0734-211X(00)18906-1].