MFIS (Metal Ferroelectric Insulator Semiconductor) capacitors were fabricated on Si(100) substrate using CeO
2
as the insulating buffer layer, SrBi
2
Ta
2
O
9
(SBT) as the ferroelectric layer, and Pt ...as the top electrode material. XRD(T) analysis was used to examine the phase transition from the as-deposited, amorphous to the polycrystalline phase of the SBT layer as a function of the anneal temperature. The influence of the anneal temperature on the capacitance of MIS/MFIS structures and the memory window of MFIS capacitors will be discussed. To investigate the effect of interdiffusion between SBT and CeO
2
, which can occur during the anneal process, Ce solution was added to the SBT solution before deposition. Pt/SBT/Pt and Pt/SBT(Ce)/Pt capacitors fabricated with this solution were characterized.
A standard 1T/1C and chain-type ferroelectric memory architecture are presented. The standard memory cell consists of a transistor connected in series to a ferroelectric capacitor while the ...chain-type cell connects these elements in parallel. Based on the different memory cells, two different arrays have been designed, simulated, and integrated on a single test chip in a 0.35μm process (not presented in this work). They are compared in regard to area, performance, and reliability. It is shown that chain FRAM has the potential to be superior to standard FRAM concerning area because of its innovative cell configuration which reduces the average number of lines per row from two to almost one and therefore removing the connectivity drawback required for bipolar polarization of ferroelectric materials compared to unipolar dielectric polarization. However, this obviously comes at the cost of limited performance and increased design complexity.
The results of structural and electrical characterizations of SrTiO3 thin films deposited onto MgO and LaAlO3 substrates by pulsed laser deposition technique are presented. The influence of substrate ...and annealing procedure on the crystalline structure and dielectric properties of these ferroelectric thin films are investigated. The obtained experimental data are analyzed in terms of the Landau theory taking into account the room-temperature lattice mismatch of the ferroelectric and substrates as well as the difference in their thermal expansion. It is shown that the behavior of the SrTiO3 thin films could not be attributed to the effect of the film/substrate mechanical coupling. As a possible nature of the observed behavior one can consider the non-stoichiometry of the film composition caused by the chemical contact of the film with the substrate and by the annealing.
The ferroelectric soft mode behaviour was studied in several SrTiO
3
(ST)films on sapphire substrates using far infrared (FIR) transmission measurements and in the bulk ST ceramics using Raman and ...FIR reflectivity measurements down to 15 K. The recently established dramatic differences in softening and soft mode width compared to single crystal behaviour were confirmed in all the cases. Clear evidence of polar clusterappearance in the pure bulk ceramics indicates that the main reason for the observed differences in thin films are inhomogeneities due to the appearance of polar clusters or even a macroscopic ferroelectric transition at about 130 K in the case of well orientedinjection MOCVD film.
Hafnium oxide films were deposited on Si (100) substrates using metal-organic chemical vapor deposition (MOCVD) and evaluated for gate dielectric applications. For this study, two types of precursors ...were tested: an oxygenated one, Hf butoxide-mmp, and an oxygen-free one, Hf diethyl-amide. Depositions were carried out in the temperature range of 350-650°C. However, the discussion is focused on amorphous films. The films were compared on the basis of growth rate, phase development, density, interface characteristics, and electrical properties. A similar amorphous to polycrystalline phase transition temperature was found for both precursors. For low deposition temperatures the growth rate for the amide precursor was significantly higher than for the butoxide-mmp precursor and films prepared with the amide precursor contained a lower carbon impurity content than with the butoxide-mmp one. The dielectric constant was slightly higher for amorphous HfO
2
deposited from the amide precursor than for the butoxide-mmp one. Only in respect to the trap density does the butoxide precursor seem advantageous.
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