PLATINUM ALLOYS AND IRIDIUM BOTTOM ELECTRODES FOR PEROVSKITE BASED CAPACITORS IN DRAM APPLICATIONS

Two types of potential bottom electrode structures for integration of ferroelectric materials in DRAM technology have been investigated: one based on iridium, the other based on platinum alloyed with oxygen get tering elements, such as B and Ti. The electrode structures, deposited on Si substrates, have been annealed in oxygen at 650 degrees C for 3 0 min and characterized by RBS and AES. It was found that alloying the Pt with 3% of alloying elements had no beneficial effect and did not improve the properties of Pt as a barrier to oxygen diffusion. At the investigated annealing conditions, oxygen diffuses through Pt or its a lloys and oxidizes the underlaying material. On the other hand, a thic kness of 1100 Angstrom Ir was found to provide a barrier to oxygen dif fusion under the same conditions. A layer of Ta in contact with Pt or Ir was found to deteriorate the barrier properties of both metals at t he investigated annealing conditions.