Pulsed laser-ablation deposition of thin films of molybdenum silicide and its properties as a conducting barrier for ferroelectric random-access memory technology

We report on the feasibility of using molybdenum silicide as a conducting b arrier for integration of ferroelectric lead zirconate titanate capacitors on Si. Thin films of MoSi2 were deposited by pulsed laser-ablation depositi on (PLD). The silicide films showed a structural transition from amorphous to orthorhombic to tetragonal phase as the temperature of deposition was ch anged from room temperature to 900 degrees C. The four-probe resistivity an d surface roughness of the films decreased with an increase in the depositi on temperature and crystallinity of the phase. Ferroelectric (La, Sr)CoO3/P b(Nb, Zr, Ti)O-3/(La, Sr)CoO3 capacitors were grown on Si/poly Si/MoSi2, an d Si/poly Si/MoSi2/Pt structures. Transmission electron microscopy (TEM) st udies of the MoSi2/LSCO and MoSi2/Pt/LSCO heterostructures indicated the fo rmation of a thin layer of SiO2. In the case of Pt/MoSi2, Pt reacts with th e silicide and forms PtSi, consuming the entire platinum layer and, thus, m akes it unsuitable as a composite barrier. Electrical testing of the LSCO/P NZT/LSCO capacitors through capacitive coupling showed desirable ferroelect ric properties on these substrates.