Atomic-layer deposited IrO2 nanodots for charge-trap flash-memory devices

Charge-trap flash- (CTF) memory structures have been fabricated by employing IrO₂ nanodots (NDs) grown by atomic-layer deposition. A band of isolated IrO₂NDs of about 3 nm lying almost parallel to Si/SiO₂ interface is confirmed by transmission electron microscopy and x-ray photoelectron spectroscopy. The memory device with IrO₂NDs shows much larger capacitance-voltage (C-V) hysteresis and memory window compared with the control sample without IrO₂NDs. After annealing at 800 °C for 20 min, the ND device shows almost no change in the width of C-V hysteresis and the ND distribution. These results indicate that the IrO₂NDs embedded in SiO₂ can be utilized as thermally stable, discrete charge traps, promising for metal oxide-ND-based CTF memory devices.