In situ preparation of high quality BaTiO3 dielectric films on Si at 350-500 °C

Reducing thermal budget of functional layers grown on Si substrates has become a necessity for their integration into contemporary manufacturing technology of microelectronics. The work presented here exemplifies one of such efforts by preparing barium titanate (BaTiO3 or BTO) films at temperatures as low as 350 degrees C on Si substrates via a CMOS-compatible RF-magnetron sputtering process. In this study, X-ray diffraction (XRD) results reveal that use of LaNiO3 (LNO) buffer layer successfully induces BaTiO3 film's transition from polycrystalline to highly c-axis oriented tetragonal in low temperature range. Moreover, encouraged by BaTiO3 films prepared at 500 degrees C that shows a nearly uniform (00l) orientation with excellent ferroelectric properties (Pr similar to 2.6 mu C/cm(2), E-c similar to 100 kV/cm, d(33) similar to 150 pm/V), we further push the deposition temperature down to 350 degrees C. While showing reduced crystallinity, these lower temperature films still possess good dielectric properties which are characterized by a stable dielectric constant of 110 +/- 5 and a small dielectric loss between 0.7 and 3 % in the frequency range of [1 kHz, 2 MHz]. We believe the finding of high quality BaTiO3 films achievable at 350 degrees C is meaningful in that it paves the road for BaTiO3's real application in Si based CMOS technology.