Lanthanum-Oxide-Doped Nitride Charge-Trap Layer for a TANOS Memory Device

A charge-trap-type Flash memory with a La₂O₃ -doped Si₃N₄ charge-trapping layer is demonstrated for the first time. An ultrathin La₂O₃ layer is inserted in the middle of a Si₃N₄ layer, followed by high-temperature annealing to mix the two layers. The La₂O₃-doped Si₃N₄ layer, irrespective of Si₃N₄ deposition processes, is found to provide deep charge-trapping sites, resulting in an excellent pre-/postcycling retention property and high reliability. The optimization of the La₂O₃ layer thickness and position in the Si₃N₄ trapping layer has been also systematically studied.