CRYSTALLIZATION PROPERTIES OF Al DOPED CeO_2 THIN FILMS DEPOSITED BY REACTIVE RF SPUTTERING WITH O_2 INTRODUCTION

Cerium dioxide films doped with Al were deposited on p type Si (100) substrates by radio frequency (RF) magnetron sputtering in an Ar atmosphere with O_2 introduction at room temperature using the CeO_2 target on which Al plates were bonded. The deposited sample was annealed in a N_2 atmosphere at temperatures from 200 to 600℃. The effective dielectric constant was increased from 9-11 in the as-deposited sample to 13-15 in the annealed sample and independent of the post-annealing temperature up to 600℃ except at 400℃ where it decreased by 20 %. The leakage current laid around the order of 10^-7 A/cm^2 but exceptionally increased by 3 orders of magnitude after post-annealing at 400℃. The observation by X-ray diffraction (XRD) and cross-sectional transmission electron microscope (XTEM) suggested that the specificity found after annealing at 400℃ was due to the deconstruction of the micro-crystalline structure. The Al peak in X-ray photoelectron spectroscopy (XPS) spectra shifted toward higher binding energies with the increase of the annealing temperature. In addition, the shift depended on the increase of the amount of O_2 introduced. These results implied CeAlO_3 formation, but no specific change was observed in Al chemical state in XPS spectrum for the 400℃ annealed sample.