The development of an enhancement-mode single-transistor SONOS cell in 0.13µm technology

An enhancement-mode Silicon-Oxide-Nitride-Oxide-Silicon (SONOS) device has been developed in 0.13μm technology platform. The single-transistor (1-T) SONOS device in NOR Flash memory array utilizes n-channel cells. The development of 1-T SONOS is not an easy feat due to many disturbs experienced by the cells during operation. By the manipulation of program/erase mechanisms and operational conditions, all disturbs can be suppressed to the manageable level. The preferred program method is by Channel Initiated Secondary Electron (CHISEL) while F-N tunneling is utilized in erase operation. Silicon-Oxynitride (SiO_xN_y) film is chosen as the ONO trapping layer because of its superior data retention performance in comparison to the silicon nitride (Si₃N₄). Characterization results of SONOS cells, with ONO film stack 26A tunnel-oxide/105A SiO_xN_y/42A top-oxide, show reasonably good program speed, erase speed, data retention, endurance, and free or has minimal effect from all disturbs.