Showing papers by "Chang Jung Kim published in 2001"
TL;DR: In this article, the authors investigated the retention behavior of the PZT-based 4Mbit random access memory (FRAM) devices and confirmed that the amount of the polarization decay varied due to the write/read voltages and baking temperature.
Abstract: Retention characteristics of a ferroelectric random access memory (FRAM) devices are strongly influenced by the integration processes and the ferroelectric material itself. In this study, we investigated the retention behavior of the PZT-based 4Mbit FRAM devices. Various heat treatment conditions were introduced to crystallize PZT films and the effect of La-doping was also observed. The nonvolatile charge of the PZT capacitor generally decreased as the increase of the baking time and finally the device failed to maintain the data. The decay rate of a sample, which was obtained through fitting the measured polarization values to the stretched exponential equation, was closely related to the crystallization process of PZT. It was also confirmed that the amount of the polarization decay varied due to the write/read voltages and baking temperature. Additionally, 1/T dependence of the logarithmic decay rate gave the activation energies for the polarization decay. The obtained activation energies were ...
4 citations
TL;DR: In this paper, the dry etching of iridium and iridium oxide (IrO2) using a hard mask has been studied in a high density Inductively Coupled Plasma (ICP).
Abstract: The dry etching of iridium(Ir) and iridium oxide(IrO2) using a hard mask has been studied in a high density Inductively Coupled Plasma (ICP). The etch rate and etch selectivity have been obtained in terms of gas chemistry including CI2/O2/Ar, HBr/O2/Ar, and C2F6/O2/Ar gases. The etch profile and the etch mechanism have been examined for various etch gases by using field emission scanning electron microscopy (FESEM) and field emission auger electron spectroscopy (FEAES). In addition, the electrical properties of the etched ferroelectric capacitors were measured for each etching gas.
2 citations
TL;DR: In this article, two sol-gel solutions were prepared with high viscosity, the conventional solution used just added propylene glycol and, the modified solution was derived from propane glycol.
Abstract: PbZrxTi1−xO3(PZT) thick films were prepared on Pt/Ti/SiO2/Si substrate with over lum-thickness by means of using chemical solution deposition(CSD). Two different sol-gel solutions were prepared with high viscosity. The conventional solution used just added propylene glycol and, the modified solution was derived from propylene glycol. We evaluated various properties of thick films prepared based on both solutions, including microstructure, crystal orientation and electric properties. The films derived from modified solution showed preferred (100) orientation which could be a consequence of the precursor difference of PZT solution. Under 550 °C, PZT (100) orientation could be obtained from X-ray diffraction patterns. We could compared the results-Various properties of PZT films derived by 1,3-propanediol system just used as a solvent- with other papers’ method. Most of all, with the modified solution, we could decreased the thickness of thermally oxidized silicon layer and the solution was a stable...
1 citations
TL;DR: In this article, a ferroelectric bismuth lanthanum titanate (Bi3.25La0.75Ti3O12) thin film was fabricated successfully on Pt/Ti/SiO2/Si substrate by chemical solution deposition method.
Abstract: Recently, ferroelectric bismuth lanthanum titanate (Bi3.25La0.75Ti3O12) thin film has been expected as a novel material for FRAM device since it has a large polarization, is fatigue free, and can be crystallized at low temperature compared to SrBi2Ta2O9 material. The BLT thin film was fabricated successfully on Pt/Ti/SiO2/Si substrate by chemical solution deposition method. The films were crystallized in the temperature range of 600 ∼700°C using rapid thermal process and quartz tube furnace. X-ray diffraction shows a single-phase film. The spontaneous polarization (Ps) and the switching polarization of BLT film annealed at 700°C for 2 min are 16.75 and 26.28 uC/cm2, respectively.