Program/erase injection current characteristics of a low-voltage low-power NROM using high-K materials as the tunnel dielectric

The program and erase injection current characteristics of a NROM with SiO2 HfO2, LaAlO3 and Al2O3 as the tunnel dielectric, respectively, are studied in this paper. Due to the lower electron and hole energy barriers introduced by LaAlO3, both the program and erase injection current densities of the NROM using LaAlO3 as the tunnel dielectric are increased dramatically. The injection efficiency is also improved significantly, which indicates that the introduction of LaAlO3 call lower the operation voltage of NROM cells. We show that the bit line voltage can be reduced to 3 V for both program and erase operations of NROM cells with LaAlO3 of 5 nm and 8 nm equivalent oxide thickness (EOT). This can greatly reduce the additional circuits to generate high voltages in a nonvolatile memory chip, meanwhile maintaining sufficient program/erase (P/E) performance and reliability. Our study also shows that the drain disturb is alleviated during programming and erasing the NROM cell with the LaAlO3 tunnel dielectric due to the lower operating voltages (VBL = 3V). Hence a low-voltage low-power NROM flash memory device operation can be achieved by using LaAlO3 as the tunnel dielectric, due to the enhancement of the P/E injection current.