SONOS-Type Flash Memory Cell With Metal /Al2O3/ SiN/Si3N4/Si Structure for Low-Voltage High-Speed Program/Erase Operation

摘要

High-quality $hbox{Al}_{2}hbox{O}_{3}$ and $hbox{Si}_{3}hbox{N}_{4}$ dielectrics synthesized in a molecular/atomic deposition system were developed and adopted as blocking oxide and tunnel dielectric, respectively in a SONOS-type nand flash memory cell. In particular, the use of trap-free $hbox{Si}_{3}hbox{N}_{4}$ as tunnel dielectric enables low-voltage erase operation due to its low barrier height for holes, and the relatively high- $k$ value of $hbox{Al}_{2} hbox{O}_{3}$ enhances the low-voltage and high-speed program/erase (P/E) operations. We fabricated and investigated nand flash memory cells with metal $/hbox{Al}_{2}hbox{O}_{3}/hbox{SiN}/hbox{Si}_{3}hbox{N}_{4}/hbox{Si}$ structure. The fabricated cell shows 3.8-V memory window with P/E conditions of $+$15 V for 100 $muhbox{s}$ and $-$10 V for 10 ms. It also shows good endurance up to 10 000 cycles and more than 1.5-V memory window after ten years.