The diffusion properties of Cu, Cu/TiN and Cu/TiN/Ti metallization on GaAs, including as-deposited film and others annealed at 350 to 550C, were investigated and compared. Data obtained from X-ray diffractometry, resistivity measurements, scanning electron microscopy, energy dispersive spectrometer and Auger electron spectroscopy indicated that in the as-deposited Cu/GaAs structure, Cu diffused into GaAs substrate, and a diffusion barrier was required to block the fast diffusion. For the Cu/TiN/GaAs structure, the columnar grain structure of TiN films provided paths for diffusion at above 450C. The Cu/TiN/Ti films on GaAs substrate were very stable up to 550C without any interfacial interaction. These results show that a TiN/Ti composite film forms a good diffusion barrier for Cu metallization with GaAs.

Titanium Nitride Diffusion Barrier for Copper Metallization on Gallium Arsenide. H.C.Chen, B.H.Tseng, M.P.Houng, Y.H.Wang: Thin Solid Films, 2003, 445[1], 112-7