Electrical Characteristics of WSi(2) Nanocrystal Capacitors with Barrier-Engineered High-k Tunnel Layers

Abstract

Nanocrystal-floating gate capacitors with WSi2 nanocrystals and high-k tunnel layers were fabricated to improve the electrical properties such as retention, programming/erasing speed, and endurance. The WSi2 nanocrystals were distributed uniformly between the tunnel and control gate oxide layers. The electrical performance of the tunnel barrier with the SiO2/HfO2/Al2O3 (2/1/3 nm) (OHA) tunnel layer appeared to be better than that with the Al2O3/HfO2/Al2O3 (2/1/3 nm) (AHA) tunnel layer. When Delta V-FB is about 1 V after applying voltage at +/- 8 V, the programming/erasing speeds of AHA and OHA tunnel layers are 300 ms and 500 mu s, respectively. In particular, the device with WSi2 nanocrystals and the OHA tunnel barrier showed a large memory window of about 7.76 V when the voltage swept from 10 to -10 V, and it was maintained at about 2.77 V after 10(4) cycles. (C) 2011 The Japan Society of Applied Physics