Self-assembly La-rich nanocrystals in metal-gate MIS structures for non-volatile memories

• We report the non-volatile memory using metal-gate MIS compatible structures.
• Nanocrystals are self-formed for memory application.
• Memory properties such as program/erase speed, memory window and endurance are measured.

TiN/ZrN/high-κ (ZrLaO)/Si (MIS) structures were fabricated. Localized La-rich oxide behaving like nanocrystal (NC) has been self-formed between ZrN cap and TiN gate metal after 850 °C annealing. The program speed of 1 μs was achieved with capacitance ratio >3. The large C–V memory window of 2 V was observed at swept voltage of ±4 V. TEM analysis shows two discrete regions (NC and metal cap), which leads to two levels of speed sensitive. The endurance properties show small degradation in flatband voltage shift after 106 cycles. The relative dielectric constant is 11.1 and equivalent oxide thickness is 7.8 nm.

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