CHARACTERISTICS OF FERROELECTRIC 60 40 PZT FILMS DEPOSITED BY METALLOORGANIC DECOMPOSITION TECHNOLOGY FOR MEMORY APPLICATIONS/

Nearly pin-hole-free ferroelectric films of Pb(Zr0.6Ti0.4)O3 (PZT) wit h uniform compositions and thicknesses were synthesized using metallo- organic decomposition (MOD) technology. The metallo-organic precursors used for these PZT films were lead diethylhexanoate, (Pb(C7H15COO)2), titanium dimethoxy-dineodecanoate (Ti(OCH3)2(C9H19COO)2), and zirconi um tetraethylhexanoate (Zr(C7H15COO)4). The film thickness, structural development and electrical properties of these films were characteriz ed using a surface profilometer, X-ray diffraction (XRD) and a standar dized RT 66 ferroelectric test system. The effect of the processing co nditions on the properties of ferroelectric 60/40 PZT films were inves tigated. The important processing parameters studied included the subs trate history, the spinning speed and time, the film thickness, the py rolysing temperature and the annealing conditions. The experimental re sults show that the structural development and electrical properties o f these 60/40 PZT films are closely correlated with these processing p arameters. The polarization-reversal characteristics and fatigue behav iour, which are important for non-volatile memory applications, were a lso studied. By optimizing the annealing conditions, a 60/40 PZT film exhibited a dielectric strength of 1 MV cm-1 and a sensed remanent pol arization value of 9.3 muC cm2 after cycling 10(10) times, This demons trates the excellent potential of PZT films for non-volatile memory ap plications. The measured dielectric-constant values for these 60/40 PZ T films were in the range of 300 to 900, which is about 75 to 220 time s larger than that of the currently used dielectric, SiO2, in dynamic random-access memory (DRAM). This fact suggests that PZT film is an ex cellent alternative for the new generation, extremely high-density DRA M applications.