Investigation On Simulation Of IGZO Channel Based Thin-Film Transistor Memory

In order to accommodate the improvement of the visual effect,there is a higher requirement for the integration of the display panel.The appearance of TFT memory based on IGZO channel can realize the unification of display module and storage module,effectively improve the integration degree of system panel,and at the same time can realize the reduction of display power consumption and the increase of panel size.The concept of TFT memory has been widely concerned by researchers since it was proposed.In this paper,the factors influencing the electrical characteristics of TFT memory are discussed theoretically.Firstly,the TFT memory based on IGZO channel is simulated by Silvaco TCAD software,and the influence of device structure and structural parameters on the electrical performance of the device is taken into account.It is shown that that bottom gate structure can obtain a stable threshold voltage,and the structure is simple and should be the first choice for research.As for structural parameters,the larger thickness of tunneling layer,the larger channel length or the smaller charge trapping layer thickness will make the memory window smaller;The material with larger forbidden band width should be selected for the charge trapping layer,so that a larger storage window can be obtained.The selection of tunneling layer should also take into account the forbidden band width and dielectric constant.As a result,devices with Al₂O₃ as the tunneling layer will have larger memory windows than devices with HfO₂ and ZrO₂ as the tunneling layer.In addition,the programming voltage is also a major factor affecting the size of the memory window.The results show that when the programming voltage is small,the storage window will increase with the programming voltage,and when the programming voltage reaches a certain value,the storage window will decrease with the programming voltage.Then,the channel carrier mobility model of TFT memory was established based on the electron transport theory,and the influences of charge trapping layer thickness,tunneling layer thickness,material of the tunneling layer,interface roughness and correlation length on the mobility were comprehensively considered.The results show that with the increase of tunneling layer thickness,the remote coulomb scattering and the remote interface rough scattering decrease.With the increase of the chargre trapping layer thickness,the remote coulomb scattering is enhanced,while the rough scattering of the remote interface is weakened.At the lower effective field intensity,the device channel will be greatly scattered by the tunneling layer material with higher dielectric coefficient,while at the higher effective field intensity,the device channel will be slightly scattered by the material of tunneling layer with higher dielectric coefficient.In addition,the larger the interface roughness or the smaller the correlation length,the stronger scattering effect will exist on the device channel.Finally,the parameters of the device are modified with the simulation results,and the changes of the electrical properties of the device before and after the modification are compared.The results show that the mobility of device channel decreases to different degrees after considering the influence of charge trapping layer thickness,tunneling layer thickness and material of tunneling layer.The decline of mobility also leads to the phenomenon that the threshold voltage of memory is too large.The greater the decline of mobility,the greater the deviation of threshold voltage.In addition,the storage window of memory is correspondingly reduced.