Nonvolatile memory characteristics of metallic nanodots as charge-storage nodes

The charge and discharge properties of NiSi nanodots in the gate oxide of MOS and MOSFET devices were investigated in order to utilize as the charge-storage nodes in a nonvolatile floating-gate memory. NiSi nanodots were formed by sputtering Ni and successive exposing to SiH4 gas. The memory characteristics of MOS and MOSFET devices which contain the NiSi nanodots in the gate oxide were obtained through the capacitance–voltage measurements and the transient threshold voltage shift measurements. The window of threshold voltage shift was achieved to be 2.5 V when the gate bias voltages of ±20 V were applied for 1 s and 500 ms, respectively. The retention time of MOSFET memory-cell was estimated to be about 10 years.