Phase-state low electron-number drive random access memory (PLEDM)

Dynamic random access memories (DRAMs) based on a transistor/capacitor cell are used as main memories in computers because of their high capacity and high speed. Since there is no gain in the present DRAM cell, it requires a large cell-capacitor to produce an adequate sense signal. In each new memory generation, structure and fabrication have become more complicated to maintain a large capacitor while miniaturizing the cell. This phase-state low electron-number drive memory (PLEDM) gain cell uses a stacked tunnel transistor (PLEDTR). Since this cell has gain, a large capacitor is not necessary. The cell size is 5F/sup 2/ where F is the minimum feature size. Its read and write times are simulated as 20ns and 5ns, respectively. In principle, it is possible with PLEDM to have a retention time longer than 10 years, enabling a nonvolatile memory to be realised.