Ferroelectric Memories using Randomly Oriented (Bi_1-xLa_x)₄Ti₃O₁₂Films

Random-Oriented (Bi,La)4Ti3O12Thin Film Deposited by Pulsed-DC Sputtering Method on Ferroelectric Random Access Memory Device

“…The major issue in the deposition of the BLT films to realize high polarization was the orientation control of each grain because of the strong anisotropy in electrical polarization [7,8,12]. The saturation polarization value (P s ) is small (~4 μC/cm 2 ) along c-axis, but large (~50 μC/cm 2 ) along a-axis or b-axis [10,12]. That is, the grain orientation in the BLT film must be aligned to the a-axis or baxis to maximize the polarization value.…”

“…The BLT material has many advantages over the PZT material [4][5][6], such as being fatigue-free on platinum electrodes and having long term reliabilities such as imprint [3,[7][8][9]. In addition, the BLT material having a Bi-layered perovskite structure has strong anisotropy of polarization values [8,[10][11][12]. Therefore, crystallographic orientations in BLT films must be controlled to maximize the polarization value.…”

A Cell Model for Non-Volatile Random Access Memory and a Subsequent Method for Increasing Density

“…Rc is proportional to the signal margin assigned to material, which depends on many variables. Signal margin assigned to material is somewhat different from sensing signal material [1,2]. If the sensing margin is higher, then the critical ratio will be larger.…”

“…Research to achieve high density is being carried out at many institutes. In the case of Ferroelectric RAM (FeRAM), there have been reports on the possibility of achieving high density through changes in the non-volatile material where data are stored [1][2][3] and in cell architecture [2]. If non-volatile RAM with good scalability is successfully commercialized, many things will change.…”