Optimization of Al2O3 Based VARIOT Engineered Tunnel Dielectric for Floating Gate Flash Scaling

We have compared different Al₂O₃-based Variot tunnel dielectrics allowing to program the memory cells with strongly reduced voltages. Despite charge trapping during cycling, the walkout can fully be compensated while maintaining a lower programming and erase voltage than with a SiO₂ tunnel dielectric. Furthermore, we have shown that, particularly for Al₂O₃ with 700C PDA, the data retention after 10k W/E cycles is as good or even better than for devices with conventional SiO₂ tunnel dielectric. These optimized stacks show great potential for further flash scaling for embedded as well as stand-alone applications.