Overview and future challenge of ferroelectric random access memory technologies

Y Kato, Y Kaneko, H Tanaka, K Kaibara… - Japanese Journal of …, 2007 - iopscience.iop.org
Y Kato, Y Kaneko, H Tanaka, K Kaibara, S Koyama, K Isogai, T Yamada, Y Shimada
Japanese Journal of Applied Physics, 2007iopscience.iop.org
We have developed a low-temperature formation technique for ferroelectrics (< 500 C),
which is crucial for the ferroelectric random access memory (FeRAM) to be embedded in a
leading-edge complementary metal oxide semiconductor (CMOS). A 53-nm-thick Bi 4 Ti 3 O
12 film was successfully formed by metalorganic chemical vapor deposition at 450 C and
subsequent annealing at 500 C. It was found that perovskite grains preferentially orient
along the (110) and (111) directions and that the fabricated Bi 4 Ti 3 O 12 capacitors show a …
Abstract
We have developed a low-temperature formation technique for ferroelectrics (< 500 C), which is crucial for the ferroelectric random access memory (FeRAM) to be embedded in a leading-edge complementary metal oxide semiconductor (CMOS). A 53-nm-thick Bi 4 Ti 3 O 12 film was successfully formed by metalorganic chemical vapor deposition at 450 C and subsequent annealing at 500 C. It was found that perovskite grains preferentially orient along the (110) and (111) directions and that the fabricated Bi 4 Ti 3 O 12 capacitors show a remnant polarization (2P r) of as large as 25.7 µC/cm 2. In addition, we have adopted a nondestructive readout operation (NDRO) technique to extend read cycle endurance, in which the switched polarization at reading is automatically rewritten by readout voltage removal. We have demonstrated stable readout characteristics at more than 10 11 cycles for 0.18 µm NDRO FeRAMs.
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