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

Abstract

Novel Sr source materials for metalorganic chemical vapor deposition (MOCVD) of SrTiO 3 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 -trien 2 and Sr(DPM) 2 -tetraen 2 , have a low melting point (43–75° C), and are liquid in phase when they are vaporized at 120–130° C. SrTiO 3 thin films were prepared on Pt/Ta/ SiO 2 /Si substrates by MOCVD using the new Sr sources. The dielectric constant of films prepared with Sr(DPM) 2 -trien 2 was 215 for 125 nm thick SrTiO 3 films, and leakage current densities were below 10 -6 A/cm 2 at 1.5 V for 80 nm thick SrTiO 3 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.