Synthesis of Novel Sr Sources for Metalorganic Chemical Vapor Deposition of SrTiO3

Novel Sr source materials for metalorganic chemical vapor deposition (MOCVD) of SrTiO3 have been developed. They were synthesized by adding amine, triethylenetetramine (trien) or tetraethylenepentamine (tetraen), to bis-dipivaloylmethanato strontium ( Sr(DPM)2, or strontium-bis-2,2,6,6-tetramethyl-3,5-heptanedionate). The new sources, Sr(DPM)2-trien2 and Sr(DPM)2-tetraen2, have a low melting point (43–75° C), and are liquid in phase when they are vaporized at 120–130° C. SrTiO3 thin films were prepared on Pt/Ta/ SiO2/Si substrates by MOCVD using the new Sr sources. The dielectric constant of films prepared with Sr(DPM)2-trien2 was 215 for 125 nm thick SrTiO3 films, and leakage current densities were below 10-6 A/cm2 at 1.5 V for 80 nm thick SrTiO3 films. The new Sr sources did not change in quality after 20-time heat cycles between room temperature and 130° C in Ar atmosphere at 40 Torr.