The Influence Of Residual Stress And Interface Effect For The Electrical Properties Of FeFET:A Phase Field Simulation

Ferroelectric field effect transistor(Fe FET) has become one of significant storage devices with its features of higher speed, lower power consumption,non-destructive readout capability. As a dielectric layer of FeFET, the performance of the ferroelectric thin film is important for electrical properties of FeFET. There are many studies have proved that the residual stress and interface effect have a great influence for the performance of the ferroelectric thin films, the residual stress and the interface effect are commonly existed due to the structure of Fe FET. Therefore, it will be necessary to study the influence of the residual stress and the interface for the electrical properties of FeFET. The influence of the residual stress and interface for the FeFET electrical properties is study by the phase field method in this work. The study result has several aspects:1. A phase field model of the ferroelectric thin films is developed and the switching of domain walls in the residual stress has been investigated. The results suggest that the residual compressive stress is applied to the direction which parallel to the film, the polarization which perpendicular to film surface enhance with the increase of the time, finally forming a single domain which perpendicular to surface.The residual tensile stress is applied to the direction which parallel to the film, the polarization which perpendicular to surface of film recede with the increase of the time, finally forming a single domain which parallel to the film surface.2. The influence of the residual stress for the hysteresis loops, C-V cures and output characters cures of FeFET is studied by combining the phase field method with the basic equations of standard MOSFET. Results show that the remnant polarization and coercive field of Fe FET increase, the value of memory window increases, the open source leakage current and close source leakage current increase with the increase of residual compressive stress. The remnant polarization and coercive field of FeFET decrease, the value of memory window decreases, the open source leakage current and close source leakage current decreases with the increase of residual tensile stress.3. The influence of interface electric field and interface strain for the electrical properties of FeFET are investigated. The results show that with the increase of electric field interface, the remnant polarization of FeFET decrease, the memory window shift to the direction of the scanning voltage increases; the open sourceleakage current and close state source leakage current of I-V curves increases and then decrease.When interface strain from compressive strain to tensile strain, the remnant polarization and coercive field gradually decrease, the remnant polarization and coercive field of P-V curves gradually decreased, the memory window C-V curves decreases;open source leakage current and standoff source leakage current of I-V curves gradually increase.