FCAT-II: A 50 ns/15 V alterable nonvolatile memory device—Part I: Experimental

A new structure for an n-channel Floating Si-gate Channel Corner Avalanche Transition nonvolatile memory device (FCAT-II) and its novel write-erase characteristics are described. The new structure is a modification of the previously reported FCAT (FCAT-I) memory device. The key improvement is better coupling between the floating gate and the control gate. This makes Fowler-Nordheim tunneling the major electron injection mechanism in the floating gate. The p⁺-p junctions placed outside the channel area are self-aligned with the floating gate and have an important role in crowding and raising the electron injection field. The device can operate in both write and erase modes at high-speed (≥ 50 ns) and low-voltage (≤15 V) conditions using only positive pulses. Another useful feature is the saturation of the high level threshold voltage independent of write pulse width greater than 50 ns. Reliability of this device is as good as that of FCAT-I.