Ionizing Radiation Effect Of MFIS Structured Ferroelectric Field Effect Transistor

Ferroelectric field effect transistor (FeFET) has many potential applications in themilitary and national defense industries with clear advantages such as non-volatility, highaccess speed, low power consumption and high radiation hardness. As one type of FeFET,The Metal-Ferroelectric thin films-insulation-Semiconductor Silicon layer field effecttransistor (MFIS-FET) represents the future of the next generation of high-performancememory. MFIS-FET satisfies the general requirements of microelectronic devices such assmall volume, simple structure and high storage density. Although there are some studiesin which lead-free ferroelectric thin film has been proved to be strongly radiation resistent,the ionizing radiation effects of FeFET is unclear. As a result, their applicability in spaceenvironment is unclear. This thesis studies the ionizing radiation effects of MFIS-FET.Firstly, we study the influence of leakage current of ferroelectric thin films under ionizingradiation. Then we consider the ferroelectric layer trapped charge induced by ionizingradiation, and study the changes of the electrical characteristics of MFIS-FET underionizing radiation. Finally, due to the existence of interface layer and the serious effect oninterface layer by ionizing radiation,we consider the effect of interface layer and studythe electrical properties of metal-ferroelectric thin film-insulator-oxide-Semiconductor Silicon layer field effect transistor (MFIOS-FET) under ionizing radiation.The main contents and results are given as follows:(1) Based on space charge limited current (SCLC) and Gross ionizing radiationmobility model, we derived a model to describe the leakage current of ferroelectric thinfilm under ionizing radiation. In this model, we also consider the change in theferroelectric dielectric constant caused by ionizing radiation, and simulate the leakagecurrent of BST ferroelectric thin film under different total ionizing doses and differentdose rates. The results are consistent with the experimental data, and show thatferroelectric thin films can be resistance to a certain dose of total dose ionizing radiation.The conclusion shows that our model can provide theoretical support for the research offerroelectric thin film under ionizing radiation.(2) Using the semiconductor device radiation theory, we derived the ferroelectriclayer trap charge induced by ionizing radiation. The ionizing radiation model ofMFIS-FET is established by combining ionizing radiation mobility model and theferroelectric polarization Lue model. We simulated capacitance-voltage(C-V)characteristics, drain current-gate voltage (ID-VGS) characteristics and the polarization characteristics of ferroelectric layer under different total ionizing dose. The results showferroelectric layer plays a role in the performance of the FeFET. When failure occurs inthe ferroelectric layer caused by ionizing radiation, FeFET will also be failed. So we mustchoose the ferroelectric materials with excellent radiation hardness.(3) Considering the effect of ionizing radiation on interface layer, we established theionizing radiation model of MFIOS-FET. In this model, we simulated thecapacitance-voltage (C-V) characteristics, drain current-gate voltage (ID-VGS)characteristics and the polarization characteristics of ferroelectric layer under differenttotal ionizing doses and different interface layers. The results show that the effects ofionizing radiation will increase the capacitance of the transistor and decrease the draincurrent. Interface layer is more vulnerable when total ionizing dose is low(less than1krad(Si)). Under high total ionizing dose (more than100krad (Si)), the changes of theferroelectric layer play a more important role on the performance of the transistor.