Charge trapping characteristics of atomic-layer-deposited HfO2films with Al2O3as a blocking oxide for high-density non-volatile memory device applications.

Charge trapping characteristics of high-relative permittivity (high-?) HfO2films with Al2O3as a blocking oxide in p-Si/SiO2/HfO2/Al2O3/metal memory structures have been investigated. All high-? films have been grown by atomic layer deposition. A transmission electron microscope image shows that the HfO2film is polycrystalline, while the Al2O3film is partially crystalline after a high temperature annealing treatment at 1000 °C for 10 s in N2ambient. A well-behaved counter-clockwise capacitance-voltage hysteresis has been observed for all memory capacitors. A large memory window of ?7.4 V and a high charge trapping density of ?1.1 × 1013cm?2have been observed for high-? HfO2charge trapping memory capacitors. The memory window and charge trapping density can be increased with increasing thickness of the HfO2film. The charge loss can be decreased using a thick trapping layer or thick tunnelling oxide. A high work function metal gate electrode shows low charge loss and large memory window after 10 years of retention. High-? HfO2memory devices with high-? Al2O3as a blocking oxide and a high work function metal gate can be used in future high-density non-volatile memory device applications. [ABSTRACT FROM AUTHOR]