Charge loss in WSi2 nanocrystals nonvolatile memory with SiO2/Si3N4/SiO2 tunnel layer

We have studied the charge loss in WSi2 nanocrystals nonvolatile memory device with silicon oxide-nitride-oxide (SiO2: 2 nm/Si3N4:2 nm/SiO2: 3 nm) tunnel layer. The WSi2 nanocrystals of 2.5 nm diameters and 3.6 × 1012 cm−2 density were formed between tunnel and control oxide layers. When the programming/erasing voltages were applied at 10 V/−10 V during 500 ms, the memory window was measured about 2.7 V and maintained at about 1.1 V after 104 s at 25 °C. In this device, the activation energies for the charge loss rates from 10% to 50% in compare to an initial charge were about 0.14 eV. This charge loss could be caused by a cycling-induced oxide damage or tunnel oxide break down. Therefore, it has a feasibility of application to highly-integrate nonvolatile memory after optimize the charge loss effect by thermal stress and improve the tunnel layer stability.