Characterization of anomalous erase effects in 48 nm TANOS memory cells

On TANOS (Tantalum Alumina Nitride Oxide Silicon) charge trap cells an anomalous effect is observed during cell erase operation. Different TANOS cell architectures are investigated including an encapsulation liner of different thickness. Especially on cells fabricated without such a liner an unintended programming is observed and characterized in detail. A new characterization method is proposed to analyze this anomalous erase effect observed as an “erase hump” in transient erase characteristics. This effect is studied and discussed in correlation with liner thickness and cell retention behavior supported by electrical field simulations for cell erase conditions.