R&D of next-generation FeRAM


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R&D Association for Future Electron Devices

R&D Projects

Ongoing

R&D of next-generation FeRAM (1999 - 2003)

·Background / challenges

At present, the most popular memory is DRAM which is volatile, and is high in power consumption because it must store information even during the passage of an electrical current. With the current ferroelectric memory is of destructive read-out type. Research and development of non-destructive read-out type ferroelectric memory is essential to further reduce power consumption and speed up the operation. For this reason, expectations are placed on the non-volatile ferroelectric memory.
(FeRAM : Ferroelectric RAM)

Technology trend

·Purpose

(1) We will realize a memory chip that can retain information once written even after it is read out many times and even if the memory is left as it is for 10 days with the power off.
(2) We will realize a memory chip that can retain information for as long as ten years, regardless the number of times the power is turned off and on, by performing a rewrite operation once a day when the power is turned on.

·Results

Quality improvement of ferroelectric thin films

A high-quality Si₃N₄film was formed on an Si substrate. On this film, a (Bi, La)₄Ti₃O₁₂ film excellent in c-axis orientation was formed. Thus, basic operation as 1T type memory was confirmed.

Optimization of circuit conifguration

Function separation 1T2C type memory was manufactured. A target current ON/OFF ratio of three figures or more was achieved. Non-destructive reading operation up to 104 times was confirmed. Also, as shown in the figure above, high integration was realized.

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