The Influence Of Ionizing Radiation On The Electrical Properties Of Ferroelectric Memory By The Phase Field

With the continuous progress of science and technology,people have further strengthened the exploration of outer space,which makes the radiation resistance of space memory devices more and more important.Ferroelectric memory,possessing the advantages of low operating voltage,fast reading and writing speed and non-volatile storage,especially its natural radiation resistance,makes it have broad application prospects in space devices.Studying the properties of ferroelectric materials under irradiation conditions is the key to mastering the irradiation resistance of ferroelectric memory.At present,a lot of experimental and theoretical studies have been carried out to studies the radiation effects of ferroelectric materials.However,there are few works focusing on the degradation of ferroelectric materials under radiation conditions from the microscopic point of view.Based on this,Monte Carlo method is used to calculate the radiation damage of ferroelectric thin films in ferroelectric memory?taking MFIS ferroelectric field effect transistor as an example?under different energy and angles of H⁺proton ionization radiation.At the same time,the theoretical model of domain structure of ferroelectric field effect transistor?FeFET?ferroelectric layer with MFIS structure is established by phase field simulation method,and the ferroelectric domain structure of FeFET with different energy and angles H⁺protons incident on FeFET is mastered.The evolution process of the domain structure of thin films in the external field was studied.By establishing the standard device model,the electrical properties of FeFETs under different energy and angles H⁺proton radiation were calculated,and the degradation law of the electrical properties of FeFETs under radiation was summarized.Specific research contents and results are as follows:?1?Monte Carlo method was used to study the damage effect of ferroelectric thin films in Pt/BaTiO₃/SiO₂/Si FeFET under proton H⁺ionizing radiation.The simulation results show that when the incident energy is 10-100 keV,the location of radiation damage will be transferred from the interface between film and electrode to inside of the film,and then to the interface between film and insulating layer with the increase of incident energy.When the incident angle is 0-75 degrees,the location of internal damage of the BaTiO₃ film will move inward at the same energy with the increase of the incident angle,mainly because of the incident energy.The bigger energy is,the stronger penetration ability is,and the higher incident angle is,the shorter range will be.?2?The phase field model of MFIS FeFET is established based on the damage of BaTiO₃ thin films.The effects of interfacial thickness,built-in electric field,oxygen vacancy,interfacial strain and frequency on the ferroelectric properties of ferroelectric thin films were studied.The simulation results show that the above factors will affect the domain structure of BaTiO₃ ferroelectric thin films,mainly the domain wall movement and domain type transition.?3?The effects of interface thickness,built-in electric field,oxygen vacancy and interface strain on the electrical properties of FeFET are studied by combining the phase field model with the MOS device equation.The results show that:?a?with the increase of interface thickness,the open-state current of FeFET decreases slightly and the closed-state current increases slightly;?b?with the increase of built-in electric field and oxygen vacancy,the residual polarization,coercive field,storage window,open-state current and switching ratio of FeFET will decrease,while the closed-state current will increase;?c?with the increase of interface strain,the residual polarization,coercive field and open-state current of FeFET will decrease.At the same time,with the increase of oxygen vacancy concentration,the residual polarization,coercive field and storage window of FeFET remain unchanged,while the open-state current decreases slightly.