Studies of thin film growth and oxidation processes for conductive Ti-Al diffusion barrier layers via in situ surface sensitive analytical techniques

Conducting diffusion barrier layers play a critical role in high-density me mory integration. We recently demonstrated that Ti-Al can be used as a diff usion barrier layer for the integration of ferroelectric capacitors with co mplementary metal-oxide semiconductor devices for the fabrication of nonvol atile ferroelectric random access memories (NVFRAMs). Here, we discuss resu lts from systematic studies designed to understand Ti-Al film growth and ox idation processes using in situ ion beam sputter deposition in conjunction with complementary in situ atomic layer-resolution mass spectroscopy of rec oil ion (MSRI) and surface sensitive x-ray photoelectron spectroscopy (XPS) . The concurrent MSRI/XPS analysis revealed that amorphous Ti-Al layers pro duced by tailored sputter-deposition methods are resistant to oxidation to at least 600 degreesC, and that oxidation occurs only when the a-Ti-Al laye rs are exposed to oxygen at > 600 degreesC, via the segregation of Ti speci es to the surface and TiO2 formation. The a-Ti-Al layers discussed in this letter could be used in the double functionality of a bottom electrode/diff usion barrier for the integration of ferroelectric capacitors with Si subst rates for the fabrication of NVFRAMs and other devices. (C) 2001 American I nstitute of Physics.