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 °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 °C that shows a nearly uniform (00l) orientation with excellent ferroelectric properties (Pr ~ 2.6 μC/cm², E_c ~ 100 kV/cm, d₃₃ ~ 150 pm/V), we further push the deposition temperature down to 350 °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 °C is meaningful in that it paves the road for BaTiO₃’s real application in Si based CMOS technology.