Studies of ferroelectric film growth and capacitor interface processes via in situ analytical techniques and correlation with electrical properties

Precise control of composition and microstructure of multicomponent oxide thin films is critical for the production of ferroelectric and high dielectric constant thin film devices. In addition, the integration of film-based capacitors with semiconductor substrates, for device fabrication, requires good control of the composition and structure of the dielectric/substrate and top electrode/dielectric interfaces to control the capacitor properties. In order to understand the processes described above, we are using a variety of integrated complementary in situ analytical techniques including time-of-flight ion scattering and recoil spectroscopy, X-ray photoelectron spectroscopy, spectroscopic ellipsometry, and ex situ methods such as transmission electron microscopy, scanning force microscopy, and scanning electron microscopy. Examples of studies recently performed by our group that are reviewed here include: (a) effects of microstructure on the oxidation of Ti-Al layers that can be used in a dual functionality as a diffusion barrier and bottom electrode for integration of ferroelectric capacitors with semiconductors; (b) studies of the surface and dielectric layer/bottom electrode interface during growth of BaxSr1-xTiO3 films on Ir/TiN/SiO2/Si for fabrication of BST capacitors for DRAMs; and (c) studies of the effect of interface contamination and structure on the electrical properties of BST capacitors for high frequency devices.