ELECTRICAL-PROPERTIES OF PARAELECTRIC (PB,LA)(NB,TI)O-3 THIN-FILMS FOR DYNAMIC RANDOM-ACCESS MEMORY DEVICES

Paraelectric (Pb.La)(Nb.Ti)O-3 (PLNT) thin films were deposited by the sol-gel method on (111)Pt/Ti/SiO2/Si substrates at temperatures as lo w as 600 degrees C for the use of ULSI (ultralarge scale integration) DRAM (dynamic random access memory) capacitors. Films exhibited a regu lar polycrystalline cubic perovskite phase and showed the presence of paraelectricity in terms of hysteresis of capacitance-voltage (C-V) an d polarization-electric field (P-E) characteristics in metal-insulator -metal (MIM) capacitors, The dielectric constants of the films are 611 for a 200 nm thick film and 619 for a 300 nm thick film in a frequenc y of 100 kHz. The charge storage density obtained from the polarizatio n measurement for a 200 nm thick film was about 50 fC/mu cm(2), while a leakage current density of 70 nA/cm(2) was observed at an applied fi eld of 100 kV/cm, These values qualify the PLNT thin films for an alte rnate storage node dielectric in DRAM capacitors, (C) 1996 American In stitute of Physics.