Cyclic Chemical-Vapor-Deposited TiO2/Al2O3 Film Using Trimethyl Aluminum, Tetrakis(diethylamino)titanium, and O2
journal contributionposted on 04.09.2008, 00:00 by Xuemei Song, Christos G Takoudis
Titanium aluminum oxide films have been studied as potential alternative gate dielectrics. However, most studies have focused on sputtered films. In this study, we demonstrate that a combination of tetrakis(diethylamino)titanium, trimethyl aluminum, oxygen, and cyclic chemical vapor deposition (CVD) is a promising approach for laminated TiO2/Al2O3 films with low impurities and high thermal stability even at low temperatures. The growth of the films is carried out in a cold-wall CVD chamber at 300°C and 0.7 Torr. Our studies show that the properties of TiO2 improve with the addition of even a few percent of Al2O3. X-ray diffraction analyses indicate that as-deposited TiO2/Al2O3 films have amorphous structure. Upon annealing as-deposited films in Ar at 700°C for 5 min, TiO2/Al2O3 films maintain their amorphous structure, while pure TiO2 films crystallize at these conditions. Atomic force microscopy shows that the surfaces of TiO2/Al2O3 films are smoother than those of TiO2 films deposited at the same conditions. Even though annealing increases the roughness of the TiO2/Al2O3 films, film roughness is still significantly lower than that of as-deposited TiO2 films. Moreover, Rutherford backscattering spectroscopy and X-ray photoelectron spectroscopy show that there is no detectable formation of interfacial silicon oxide and negligible carbon impurity in as-deposited TiO2/Al2O3 films.