Masaru Umeda

A POTENTIAL AND NOVEL HIGH k DIELECTRICS SUITABLE FOR DRAM

ABSTRACT The dielectric and ferroelectric properties of a novel high-k ‘Y5V’ (Ba1 − xLax) (Ti1 − x/4 −yCey)O3 ceramics (x = 0.03, y = 0.05−BL3TC5) with cubic symmetry and fine-grained (∼ 0.9 μ m) microstructure were investigated in detail. BL3TC5 shows strong diffuse phase transition and high k behavior (ϵ ′RT > 10000) from 1 to 100 k Hz in the vicinity of room temperature, and meets EIA specifications ‘Y5V’ and ‘Z5U’ at 1 k Hz when the dielectric relaxation effect is considered. The paraelectricity and high-k behavior around room temperature suggest that BL3TC5 is a promising candidate for future DRAM application.

Influence of the Top Metal Electrode on P-V Hysteresis Loops Behavior of 1-μm Thick PZT Films Deposited on a Pt/TiN/Si Substrate Prepared by MOCVD

The effect of various top electrodes (Au, Ag, Cu and Al) on the hysteresis loop behavior of 1-μm thick PZT has been investigated. The PZT films and PT bottom electrode were prepared by MOCVD, and various top electrodes were deposited by evaporation. Using an Ag and Cu top electrode, an improvement in the polarization hysteresis loops of PZT films was observed compared to the other electrodes (Au and Al). A well-saturated P-V hysteresis loop was obtained when Ag and Cu top electrodes were applied. By applying an Au electrode, a decrease in polarization was observed, and the Al top electrode produced P-V hysteresis loops with para-electric behavior. The improvement in the polarization hysteresis loops was affected by the electrical conductivity of the top metal electrode. Namely, a faster supply of compensation charges, which are required to bind polarization charges located near the interface in PZT films, was obtained as the conductivity of the top electrode increased. The electrical conductivity of the metals displayed the following trend: (Ag>Cu>Au>Al).

1 Tbit/in.2 Very-High-Density Recording in Mass-Productive Polycrystalline Ferroelectric Thin Film Media

We demonstrate very-high-density ferroelectric recording experiments of 1 Tbit/in.2 in polycrystalline Pb(Zr,Ti)O3 (PZT) thin film for the first time. A high-quality polycrystalline PZT thin film was successfully deposited on a silicon substrate with a SrRuO3 (SRO) electrode by metal–organic chemical vapor deposition (MOCVD). The roughness of the PZT film was reduced to less than 1 nm by chemical mechanical polishing (CMP). The PZT film has very high controllability for domain inversion. Our fabrication process also enables high productivity. Therefore, our PZT film has potential to be a mass-productive ferroelectric recording medium for high-density storage systems.