Platinum-induced hysteresis and nonvolatile memory properties in MOS systems (PLATMOS)

The effect of diffused platinum on MOS structures has been studied using high-frequency capacitance-voltage techniques. The materials used were and oriented p-type silicon substrates of 3-5-Ω.cm resistivity. All the platinum diffusions were performed at 1000°C in a dry nitrogen ambient for various times between 10 and 300 min. Experimental results are presented which show that platinum diffusion produces hysteresis effects in the MOS system which have not previously been observed. The hysteresis is found to be very strongly dependent on diffusion time and crystal orientation, being much more pronounced in wafers than . All the experimental observations point to this phenomenon being associated with some bias-dependent charge storage at the oxide-silicon interface or mobile platinum ions in the oxide. The precise nature of the charge-storage mechanism is not completely understood; however, the platinum-induced hysteresis raises the possibility of being used as a memory element due to its nonvolatile property.