SnO2 thin films doped with Sb (ca. 3%) were deposited on glass and silicon substrates by magnetron sputtering and heat-treated by laser or isothermal treatment. The films were characterized for their composition, morphology, and crystalline structure by X-ray diffraction (XRD) and transmission electron microscopy (TEM). It was found that the tin oxide films consisted only of the SnO2 tetragonal phase; they were well crystallized and no microstructural defects were observed. The average grain size of the laser-treated films was approximately 6.3-8.9 nm, which is 2 times smaller than the grain size of the isothermally treated films.