The resistance random access memory device (ReRAM) is a nonvolatile memory device in which the memory element has a two-terminal structure including a variable resistance layer sandwiched between two electrodes. The resistance random access memory device has a simpler cell structure than other memory devices, and hence is considered to be easily scaled. Thus, the resistance random access memory device is drawing attention as a promising candidate for the next-generation high-capacity memory device for replacing existing products, such as NAND flash memories, widely commercialized as high-capacity memory devices.
As the variable resistance material constituting the variable resistance layer of the resistance random access memory device, various materials are investigated, such as transition metal oxide materials, sulfide materials, perovskite oxide materials, semiconductor materials, and so on. Among them, the resistance random access memory device with the material of the variable resistance layer being a semiconductor material such as amorphous silicon has high compatibility with the CMOS process, and hence is promising for commercialization. However, such a resistance random access memory device with the variable resistance layer formed from a semiconductor material has the problem of insufficient retention performance in the write state, i.e., the low resistance state.
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