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The future information technology world needs a simple identification and secure information storage medium. The advanced smart card is a promising technology to extend information-providing services from terminal (PC and mobile phone) dominated schemes to more flexible schemes in which the users’ intention dominates. In this smart card, unique identification, individual information and values are...
A review on ferroelectric thin films used for nonvolatile random access memories is given. Particular attention is paid to fundamental limitations on the materials. Optimization of ferroelectric films by impurity doping and grain-size control is first discussed; then size effects are considered (both thickness and lateral dimensions) from the point of view of both depolarization field instabilities...
In this chapter, materials integration strategies for the fabrication of high-density nonvolatile ferroelectric random access memories (FeRAMs), are discussed, in which unique combinations of in situ and ex situ analytical techniques capable of providing information about thin-film surface and interface processes at the atomic scale are used. These methods are also useful for establishing composition--microstructure--property...
A review on ferroelectric thin films used for nonvolatile random access memories is given. Particular attention is paid to fundamental limitations on the materials. Optimization of ferroelectric films by impurity doping and grain-size control is first discussed; then size effects are considered (both thickness and lateral dimensions) from the point of view of both depolarization field instabilities...
The static domain pattern of ferroelectric thin films results from the crystal structure of the film and the misfit strain caused by the substrate. A comparison of conceptual considerations and experimental results of atomic force microscope studies is presented. The motion of the domain walls is analyzed with respect to reversible and irreversible jumps as extracted from small-signal C--V and large-signal...
A chain FeRAM (TM) is a solution for future high-density and high-speed nonvolatile memory. One memory cell consists of one transistor and one ferroelectric capacitor connected in parallel, and one memory cell block consists of a member of cells in series. This configuration realizes a small memory cell of 4 F$$^{2}$$ size in the ideal case and a fast random access time. In this chapter, overview...
In this chapter, recent progress in our group in the area of thin-film ferroelectrics is reviewed. The specific focus is on nanoscale phenomena such as polarization relaxation dynamics and piezoelectric characterization in model thin films and nanostructures, using voltage-modulated scanning force microscopy. Using this technique, we show the three-dimensional reconstruction of the polarization vector...
Key technologies for portable equipment are low-voltage operation, low power consumption, and protocol-flexibility. Ferroelectric technology can contribute nonvolatility and flexibility to the portable systems. In this chapter, process technologies for low-voltage operation are first described. Then, nonvolatile logic circuits are introduced for low power consumption. Several nonvolatile latch circuits,...
Ferroelectric nonvolatile memories (FeRAM) have been mass-produced since 1992 and densities up to 256 kb are currently available in a range of products. Both memory density and the market for FeRAM are increasing at an exponential rate due to the demands for nonvolatility, high read/write endurance, fast access speed, and low-power operation. Current applications include smart cards, data collection...
A sub-nanometer resolution scanning nonlinear dielectric microscopy (SNDM) was developed for the observation of ferroelectric polarization. We also demonstrate that the resolution of the SNDM is higher than that of conventional piezo-response imaging. Next, we report a new SNDM technique detecting the higher nonlinear dielectric constants $$\varepsilon_{3333}$$ and $$\varepsilon_{33333}$$. It is expected...
This chapter provides an introduction to the circuit design aspects of ferroelectric random access memories (FeRAM). A FeRAM stores binary data in an array of FeRAM cells, each consisting of either two transistors and two capacitors (2T-2C cell) or one transistor and one capacitor (1T-1C cell). The 2T-2C cell stores both the binary data and its complement on the two capacitors. Compared to the 1T-1C...
In this chapter, properties of novel Si-substituted ferroelectric films are presented. The films are a solid solution between Bi $$_{2}$$ SiO $$_{5}$$ (BSO) and conventional ferroelectric materials such as Bi $$_{4}$$ Ti $$_{3}$$ O $$_{12}$$ , SrBi $$_{2}$$ Ta $$_{2}$$ O $$_{9}$$ , and Pb(Zr,Ti)O $$_{3}$$ , which were formed by a sol-gel spin-coating method. It was found...
In this chapter, recent progress in our group in the area of thin-film ferroelectrics is reviewed. The specific focus is on nanoscale phenomena such as polarization relaxation dynamics and piezoelectric characterization in model thin films and nanostructures, using voltage-modulated scanning force microscopy. Using this technique, we show the three-dimensional reconstruction of the polarization vector...
Ferroelectric nonvolatile memories (FeRAM) have been mass-produced since 1992 and densities up to 256 kb are currently available in a range of products. Both memory density and the market for FeRAM are increasing at an exponential rate due to the demands for nonvolatility, high read/write endurance, fast access speed, and low-power operation. Current applications include smart cards, data collection...
A capacitor-on-metal/via-stacked-plug (CMVP) memory cell was developed for the 0.25 micr meter CMOS logic embedded FeRAM. Using a 445 C MOCVD Pb(Zr,Ti)O_{3}$ process, a ferroelectric capacitor is formed after CMOS logic fabrication. Thus, FeRAM can be embedded without changing any logic devices and processes. Furthermore, this technology enables cell size reduction (3.2 micro squaremeter for 1T-1C),...
This chapter provides an introduction to the circuit design aspects of ferroelectric random access memories (FeRAM). A FeRAM stores binary data in an array of FeRAM cells, each consisting of either two transistors and two capacitors (2T-2C cell) or one transistor and one capacitor (1T-1C cell). The 2T-2C cell stores both the binary data and its complement on the two capacitors. Compared to the 1T-1C...
A capacitor-on-metal/via-stacked-plug (CMVP) memory cell was developed for the 0.25 micr meter CMOS logic embedded FeRAM. Using a 445 C MOCVD Pb(Zr,Ti)O_{3}$ process, a ferroelectric capacitor is formed after CMOS logic fabrication. Thus, FeRAM can be embedded without changing any logic devices and processes. Furthermore, this technology enables cell size reduction (3.2 micro squaremeter for 1T-1C),...
The current status of the fabrication and integration of ferroelectric-gate field effect transistors (FETs) is reviewed. Novel applications of ferroelectric-gate FETs are first discussed, which include a single-transistor-cell-type digital memory, reconfigurable LSIs, and an analog memory for an artificial neural network. In the neural network application, the fabrication and basic operation of a...
In ferroelectric random access memories (FeRAMs), the difference in the displacement charge between the two polarization states is fundamental to discriminate the binary states, ‘‘1’’ and ‘‘0’’. Therefore, the durability of the difference in the displacement charge and circuit techniques for sensing the difference are intimately related to the reliability of FeRAMs. In this chapter, we deal with electrical...
Recent research by our group, concerned with the preparation of ferroelectric thin films by MOCVD, is summarized. MOCVD has been investigated as a most practical preparation method to realize a high-density FeRAM, because of the good step coverage and the uniform composition and film thickness over a large area. In addition, it has recently become possible to decrease the process temperature to obtain...
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