A study of CVD growth kinetics and film microstructure of zirconium dioxide from zirconium tetra-tert-butoxide

The chemical vapor deposition (CVD) of polycrystalline zirconium dioxide (ZrO2) from zirconium tetra-tert-butoxide {Zr[OC(CH3)(3)](4)}is described. The ZrO2 films, which were deposited on Si(100), were characterized by scanning electron microscopy, ellipsometry, X-ray diffraction, Rutherford backscattering spectrometry, and Auger electron spectroscopy. Deposition was studied between 380 and 825 degreesC, and at precursor pressures between 4 x 10(-5) and 1 x 10(-4) Torr. Film microstructure depends on deposition temperature, with low temperatures (<420 degreesC) leading to the formation of nearly equi-axed grains, moderate temperatures (450-550 degreesC) producing oblate grains, and high temperatures (>700 degreesC) giving rise to triangular grains. Film density decreases with increasing deposition temperature. The kinetics for steady-state ZrO2 growth were studied as functions of temperature and precursor pressure. Results were fit to a two-step kinetic model involving reversible precursor adsorption followed by irreversible decomposition to ZrO2. The induction period (t(i)) to growth was measured as a function of temperature for a single precursor pressure (9.4 x 10(-5) Torr); ti decreases with temperature from 490 s at 381 degreesC to less than 1 s at 743 degreesC.