The thermal stability of zirconium aluminate high-k film on strained SiGe layer

Zr/sub 0.6/Al/sub 0.4/O/sub 1.8/ dielectric films were deposited directly on strained SiGe substrate at room temperature by ultra-high vacuum electron-beam evaporation (UHV-EBE) and then annealed in N/sub 2/ under various temperatures. X-ray diffraction (XRD) reveals that the onset crystallization temperature of the Zr/sub 0.6/Al/sub 0.4/O/sub 1.8/ film is about 900/spl deg/C, 400/spl deg/C higher than that of pure ZrO/sub 2/. The amorphous Zr/sub 0.6/Al/sub 0.4/O/sub 1.8/ film with a physical thickness of /spl sim/ 12 nm and an amorphous interfacial layer (IL) with a physical thickness of /spl sim/3 nm have been observed by high-resolution transmission electron microscopy (HRTEM). In addition, it is demonstrated there is no undesirable amorphous phase separation during annealing at temperatures below and equal to 800/spl deg/C in the Zr/sub 0.6/Al/sub 0.4/O/sub 1.8/ film. X-ray photoelectron spectroscopy (XPS) reveals that zirconium and aluminum are both in the fully oxidation states.