Tetragonal zirconia coatings (ZrO2) without doping any trivalent impurities have been deposited by metal-organic chemical vapor deposition (MOCVD) on (100) Si single crystals, using Zr(thd)4 precursor. The surface and cross-section morphologies were observed with Field-Emission-Gun Scanning Electron Microscopy (FEG-SEM). The crystalline structures were characterized by grazing incident X-ray diffraction (GIXRD). Crystallographic textures of these films were studied for both {011}t and {110}t planes by pole figure recording by X-ray diffraction under a 4-circle goniometer. The internal stresses were measured with the use of sin2 psi method. In order to study the relationship of microstructures and tetragonal phase stabilization in ZrO2 films, annealing experiments were taken at different temperature. The results show that the critical crystallite size for tetragonal to monoclinic phase transformation is different for samples with different initial microstructures. Besides the critical crystallite size and the residual stress, the texture and crystallite morphology of the ZrO2 films are responsible for the stabilization of the metastable tetragonal phase.