Moreover, we have also fabricated TFT-SONOSs with double-gated configuration and comparisons were made with their single-gated counterparts.
Regarding the programming speed and erasing speed, the characteristics of TFT-SONOS with nanowire structure are comparable to those of conventional SONOS. The double-gated configuration in the proposed device does not seem to contribute nor enhance the programming speed or erasing speed. On the other hand, the reliability of TFT-SONOS is still worse than that of the conventional SONOS, due to poor quality of tunneling oxide and the horn-shaped structure of the nanowire channels. However, the double-gated configuration is found to improve the retention of TFT-SONOS with nanowire structure. Although there are many disadvantages lying ahead and need to be improved, we demonstrate the feasibility of nonvolatile memory with nanowire-TFTs fabricated by the simple and production-worthy sidewall spacer technique.