Electrical and physical characteristics of metal–oxide–semiconductor structured nonvolatile memory with HfLaxTiyOz charge trapping layers

Abstract

A HfLaxTiyOz film that embeds in a Hf2La2O7 dielectric has been presented as the charge trapping layer (CTL) of metal–oxide–semiconductor (MOS) structures for nonvolatile memory (NVM). First, the physical and electrical characteristics of the MOS structures for NVM with HfLaxTiyOz CTLs treated at various postdeposition annealing conditions are examined. Then, the electrical and reliability properties, including hysteresis windows, programming/erasing (P/E) time, endurance, and retention of the MOS structures, with various Ti and O contents incorporated into the HfLaxTiyOz CTLs, are investigated. The results indicate that a 2.7 V hysteresis window is achieved by scanning over the range of ±7 V. The density of charge trap states is estimated to be 2.03 ± 0.06 × 1013 cm−2 during the C–V hysteresis sweep over the range of ±7 V for the HfLaxTiyOz CTL. Better properties, namely, a small memory window narrowing after 104 P/E cycles and a 7% charge loss after 10 years, are demonstrated for the HfLaxTiyOz CTL with a combined titanium content of 17.79 ± 0.53% and an oxygen content of 70.89 ± 2.13%.