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Antireduction characteristics of IrO2/Pb(ZrxTi1−x)O3(PZT)/Pt ferroelectric capacitors are improved by post annealing. When an as-processed capacitor receives a 3% hydrogen annealing at 300 °C (a process condition for fabricating the interlayer dielectric), capacitor characteristics are heavily degraded. This is because Ir that is produced by IrO2 reduction plays a catalytic role in PZT reduction. By contrast, if the IrO2/PZT/Pt capacitor is post annealed in O2 atmosphere at 600 °C for 1 h, the capacitor characteristics can be maintained even if it undergoes the hydrogen annealing. The O2 annealing improves the crystallinity of the IrO2 top electrode and excess PbOx in sol-gel derived PZT diffuses into the IrO2 film. As a result, antireduction characteristics of the IrO2 top electrode itself are drastically improved and the PZT film becomes stoichiometric at the same time. Exclusion of excess PbOx in PZT results in an increase in spontaneous polarization of the IrO2/PZT/Pt ferroelectric capacitor. Furtherm...

The disappearance of ferroelectricity in Pb(Zr0.52,Ti0.48)O3 (PZT) thin-film capacitors, which is caused by heat treatment in a reductive ambience, is investigated. Bare PZT films are not damaged by annealing in a hydrogen-containing atmosphere (H2 annealing) up to 400 °C, whereas a PZT capacitor with Pt electrodes loses its ferroelectricity during annealing at less than 300 °C. We have found that the degradation of ferroelectricity depends upon the metal used for the top electrode of the PZT capacitor. The increased degradation in the case of a PZT capacitor with Pt electrodes can be explained by a catalytic reaction on the Pt surface. We have made the ferroelectricity of a Pt/PZT/Pt capacitor retained even after the H2 annealing at 300 °C, or above, simply by oxidizing it before the H2 annealing.

Lead zirconate titanate (PZT) thin films were prepared by reactive coevaporation with high-concentration ozone. PZT thin films that demonstrate the highest charge storage density (280 fC/μm2 at 1.5 V for 75-nm-thick film) yet reported have been fabricated. No fatigue was observed after 1011 polarization switching cycles even though a Pt electrode is used. A low leakage current of

The deposition temperature dependence and postannealing temperature dependence of the properties of metal-organic chemical vapor deposited Ru film were investigated in order to minimize the leakage current density across Pt∕Bi4−xLaxTi3O12∕Ru ferroelectric capacitors. With postannealing at 400°C, leakage current density was decreased to 1∕100 of the as-deposited sample, although surface morphology and crystallinity hardly changed. The improvement effect of the leakage current was not pronounced, even if the postannealing temperature was further increased. These observations suggest that the effect of crystallinity and surface morphology of Ru film is less significant for the leakage current density, and alternative phenomenological model to explain these results is presented.

A new contactless characterization technique based on microwave impedance measurement was developed and applied to the nondestructive measurement of deep level concentration in semi‐insulating GaAs crystals. Using this new technique, the nonuniform distribution of EL2 was measured in GaAs wafers used for IC fabrication. Taking advantage of the nondestructive and contactless feature of this new technique, both the EL2 concentration and the threshold voltage (Vth) of metal semiconductor field effect transistors were measured in the same sample. By analyzing the relation of these two quantities, it is found that the activation efficiency of implanted Si atoms is lower in the EL2 richer region, and vice versa. A possible mechanism to explain the experimental data is discussed in relation with crystal nonstoichiometry.

Tungsten‐related deep levels in a silicon crystal are investigated using microwave and conventional deep level transient spectroscopy. It is found that tungsten atoms have two diffusion constants. Most tungsten atoms stay near the surface of Si crystal, but the remainder go deeper than 1 μm from the surface. It is also found that tungsten atoms make both a hole trap of 0.41 eV and an electron trap of 0.22 eV. Device characteristics are found to be seriously degraded due to deep levels made of deeply diffused tungsten atoms.