An InGaZnO Charge-Trapping Nonvolatile Memory With the Same Structure of a Thin-Film Transistor

A new charge-trapping nonvolatile memory (NVM) with a fully same structure to thin-film transistor (TFT) is investigated. Different from the conventional NVM with block layer/charge-trapping layer/tunneling layer stack for charge storage, this NVM uses the metal-hydroxyl (M-OH) defect at the back channel for charge storage, which forms by the reaction of IGZO with moisture and acts as acceptor-like deep-level traps. Devices with various M-OH contents are prepared by changing thermal treatment. The device with high M-OH content displays good NVM performance in terms of its large memory window (1.5 V at +/- 10 V, 1s), high program/erase speeds (1.1 V at 10 V, 1 ms) and good data retention (78.9% retention after 10 years); for comparison, the device with low M-OH content exhibits good TFT characteristics in terms of its small sub-threshold swing (226 mV/dec), high carrier mobility (8.1 cm(2)/V.s) and good electrical stability (memory window similar to 0.2 V at +/- 10 V, 1s). Since the NVM and TFT have the same structure, both the devices can be simultaneously prepared combined with an extra treatment to modulate the M-OH content at the back channel, thus contributing to system-on-panel development.