EFFECTS OF POSTANNEALING ON THE CONDUCTION PROPERTIES OF PT (BA,SR)TIO3/PT CAPACITORS FOR DYNAMIC RANDOM-ACCESS MEMORY APPLICATIONS/

Pt/(Ba, Sr)TiO3/Pt capacitors were fabricated on TiN/Ti/Poly-Si/SiO2/S i substrate by sputtering technique and effects of post-annealing cond itions on the current vs. voltage (I-V) characteristics of the capacit ors were investigated It was found that leakage currents of Pt/BST/Pt capacitors were greatly depended on the annealing sequence as well as annealing atmosphere, BST films annealed under Ar/H-2 or N-2 showed mu ch higher leakage current than as-deposited films regardless of the fa brication of top electrode. On the contrary, annealing under O-2 atmos phere was effective to reduce leakage currents of the BST films if ann ealing process was carried out after fabrication of top electrode. Lea kage current of Pt/BST(50nm)/Pt capacitors annealed under O-2 atmosphe re at 500 degrees C for Ih after fabrication of Pt top electrode was 5 x 10(-7) A/cm(2) even at 7V. In this work, effects of annealing condi tions on the I-V properties of Pt/BST/Pt capacitors were explained wit h energy band diagram in which oxygen vacancies play a key role.