铁电场效应晶体管的保持性能与负电容效应分析-analysis of retention performance and negative capacitance effect of ferroelectric field effect transistor.docx

摘要温度达到最佳值时，铁电薄膜负电容效应最明显，温度若再升高(或者降低)，铁电薄膜负电容效应逐渐减弱直至消失。该研究成果抓住了环境温度这一关键因素，对低功耗场效应晶体管在特定环境温度下的设计与应用具有重要的指导意义。5、考虑铁电薄膜的负电容效应，我们针对环栅新型铁电场效应晶体管提出了一个理论模型，并运用该模型对其电学性能包括电容-电压(C-V)、电流-电压(I-V)进行了研究。研究结果表明：负电容环栅铁电场效应晶体管表现出比传统正电容环栅场效应晶体管优越的一些电学性能，比如栅电极能更好地控制沟道静电势、小的亚阈值摆幅(60mV/dec)、以及大的输出电流等。该成果能很好地指导高速转换、低功耗环栅铁电场效应晶体管的设计。关键词：铁电电容器；保持性能；铁电场效应晶体管；铁电薄膜负电容；亚阈值摆幅ABSTRACTInrecentyears,ferroelectricgatefield-effecttransistor(FeFET),asonetypeofferroelectricrandomaccessmemory(FeRAM),iscurrentlyregardedasoneofthemostpotentialnextgenerationmemorywithclearadvantagessuchasitssimplestructure,nondestructiveread-outoperation,non-volatility,lowpowerdissipation,highendurance,highspeedwriting,highdensity,irradiationhardness,andcompatiblewiththeprocessofintegratedcircuit(IC).However,FeFETshavenotbeenputintopracticalapplicationasaresultofitsrelativelyshortretentiontime.Additionally,howtoreducethepowerconsumptionandimprovethestabilityofthesystemonchipwillprovetobeaproblemforpeoplewhentheFeFETsarecommonlyused.Inordertosolvethesetwoproblems,firstly,inthisthesis,theadvencesoftheferroelectricmaterialsandferroelectricmemoryarereviewedintheintroduction,includingtheclassificationandphysicalcharacteristicsoftheferroelectricthinfilms,andthedevelopmenthistory,currentstatusandexistingproblemsoftheferroelectricmemory.Then,onthebasisofintroduction,theretentionproperyofferroelectricthinfilmcapacitorandthenegativecapacitanceeffectofFeFETaremainlyinvestigatedbycombiningthetheoreticalmodelingandnumericalanalysis.Themaincontentsandconclusionsareasfollows:Depolarizationfieldinmetal-ferroelectric-insulator-semiconductor(MFIS)capacitorswithaferroelectric-electrodeinterfacelayerwasderivedtheoreticallyinthiswork.ThepolarizationrelaxationcharacteristicswereinvestigatedindetailsbasedonLou’spolarizationretentionmodel.ItisfoundthattheretentiontimeofMFIScapacitorcanbeimprovedeffectivelybyusingrelativelyhighdielectricconstantferroelectricthinfilmandrelativelythickferroelectricthinfilm.Additionally,agoodferroelectric-electrode