Nonvolatile floating gate memory containing AgInSbTe–SiO2 nanocomposite layer and capping the HfO2/SiO2 composite blocking oxide layer

Abstract

An extremely large memory window shift of about 30.7 V and high charge storage density = 2.3 × 1013 cm−2 at ±23 V gate voltage sweep were achieved in the nonvolatile floating gate memory (NFGM) device containing the AgInSbTe (AIST)–SiO2 nanocomposite as the charge trap layer and HfO2/SiO2 as the blocking oxide layer. Due to the deep trap sites formed by high-density AIST nanocrystals (NCs) in the nanocomposite matrix and the high-barrier-height feature of the composite blocking oxide layer, a good retention property of the device with a charge loss of about 16.1% at ±15 V gate voltage stress for 104 s at the test temperature of 85 °C was observed. In addition to inhibiting the Hf diffusion into the programming layer, incorporation of the SiO2 layer prepared by plasma-enhanced chemical vapor deposition in the sample provided a good Coulomb blockade effect and allowed significant charge storage in AIST NCs. Analytical results demonstrated the feasibility of an AIST-SiO2 nanocomposite layer in memory device fabrication with a simplified processing method and post-annealing at a comparatively low temperature of 400 °C in comparison with previous NC-based NFGM studies.