Electrical properties of SrTiO3 based MIS structures for DRAM applications

Polycrystalline SrTiO3 thin films were prepared on p- type silicon substrate by sol-gel technique. The films were deposited at room temperature and annealed at various temperatures. The integrability of the films with silicon substrate was investigated through the C-V characteristics of the MIS device. The C-V characteristics show a negative flat band shift due to the presence of positive charges existing in the film. The effective dielectric constant was determined from the capacitance value at accumulation region and it was found to depend on the annealing temperature. The maximum values of dielectric constant were obtained for films annealed in the range 600 to 700 degrees C. The density of the interface states in the film is evaluated and found to be about 10(11)/cm(2). The I-V characteristics exhibit behaviour similar to conventional MIS structures. The leakage currents are of the order of nanoamperes. The conduction mechanism has been analyzed.