Thin films of tantalum pentoxide, a possible candidate for high-k dielectric gate oxides in integrated circuits, were studied by transmission electron microscopy (TEM). The atomic-layer-deposited material is amorphous, crystallizing into the orthorhombic (L) phase after annealing in the temperature range 750~850 oC. In situ TEM observations allow the kinetics of the reaction to be established in detail. A combination of TEM and focused ion beam (FIB) techniques was used to determine the capacitance of individual crystallites of known orientation, whereupon it was established that the property differences were less than 10% for orthogonal orientations.

Keywords: Crystallization, tantalum oxide, electron microscopy, focused ion beam, anisotropy, dielectric constant