HfO_2中间隙氧缺陷特性第一性原理研究
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摘要
运用第一性原理计算研究了HfO2中间隙氧缺陷的特性。对HfO2中不同位置的间隙氧缺陷的形成能进行了计算,找出了最稳定的间隙氧缺陷位置,并对该位置缺陷计算了缺陷能级、态密度(DOS)和电荷俘获能;另外,还计算了间隙氧缺陷之间的距离对HfO2性质的影响。计算结果显示间隙氧缺陷能够同时俘获电子和空穴,具有两性特征;俘获的电荷主要聚集在间隙氧和最近邻氧原子附近;间隙氧之间距离增大会使得缺陷之间由吸引变为排斥,排斥力随距离继续增大而减小,并且缺陷引入的受主能级量子态数显著增加,这有利于空穴隧穿电流增大,可以用来实现存储层电荷的快速擦除。
The characteristics of interstitial oxygen(IO)in HfO2 have been studied by exceuting first priciple caculation.The formation energies of IOs at different positions in HfO2 have been calculated for the stablest site.The defect energy level,density of states(DOS)and charge trapping energy of this location have been computed.The impact of distance between IOs on the features of HfO2 has been calculated.The results of calculation confirm that IO has amphoteric property for it can capture electron and hole at the same time.The charges trapped mainly gather around the interstitial oxygen and the nearest neighbor atom of oxygen.The increasing distance between IOs changes the coulomb force between two defects from attraction to repulsion,and the repelling force decreases as the distance increases continually.Besides,the acceptor levels introducted by defect significantly increase the number of quantum states,which were advantageous to enhance the hole tunneling current that can be used to realize the rapid erasion of the storage layer charge.
The characteristics of interstitial oxygen(IO)in HfO2 have been studied by exceuting first priciple caculation.The formation energies of IOs at different positions in HfO2 have been calculated for the stablest site.The defect energy level,density of states(DOS)and charge trapping energy of this location have been computed.The impact of distance between IOs on the features of HfO2 has been calculated.The results of calculation confirm that IO has amphoteric property for it can capture electron and hole at the same time.The charges trapped mainly gather around the interstitial oxygen and the nearest neighbor atom of oxygen.The increasing distance between IOs changes the coulomb force between two defects from attraction to repulsion,and the repelling force decreases as the distance increases continually.Besides,the acceptor levels introducted by defect significantly increase the number of quantum states,which were advantageous to enhance the hole tunneling current that can be used to realize the rapid erasion of the storage layer charge.
引文
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[3]Molas G,Bocquet M,Vianello E,et al.Reliability of charge trapping memories with high-k control dielectrics[J].Microelectron Eng,2009,86:1796-1803.
[4]Larcher L,Padovani A.A high-k related reliability issues in advanced non-volatile memories[J].Microelectronics Reliability,2010,50:1251-1258.
[5]You H W,Choa W J.Charge trapping properties of the HfO2layer with various thicknesses for charge trap flash memory applications[J].Appl Phys Lett,2010,96:1-3.
[6]Zhu Chenxin,Xu Zhongguang,et al.Investigation on interface related charge trap and loss characteristics of highk based trapping structures by electrostatic force microscopy[J].Appl Phys Lett,2011,99:1-3.
[7]Foster A S,Lopez Gejo F,Shluger A L,et al.Vacancy and interstitial defects in hafnia[J].Physical Review B,2002,65:1-13.
[8]Liu Jing,Wang Qin,et al.A metal/Al2O3/ZrO2/SiO2/Si(MAZOS)structure for high-performance non-volatile memory application[J].Semicond Sci Technol,2010,25:1-4.
[9]Xing Yumei,Tao Kai,Yu Yuehui,et al.Preparation of high-quality HfO2thin films on SOI materials[J].Journal of Functional Materials,2004,35:736-738.
[10]Zhang Haowei,Gao Bin,et al.Effects of ionic doping on the behaviors of oxygen vacancies in HfO2and ZrO2:a first principles study[C]//SISPAD,2009.155-158.
[11]Zhang Wei,Hou Zhufeng.Interaction and electronic structures of oxygen divacancy in HfO2[J].Phys Status Solidi B,2012,1-4.
[12]Cockayne E.Influence of oxygen vacancies on the dielectric properties of hafnia:first-principles calculations[J].Physical Review B,2007,75:1-8.
[13]Cho D Y,Lee J M,Oh S J,at al.Influence of oxygen vacancies on the electronic structure of HfO2films[J].Phys Rev B,2007,76:1-5.
[14]Sandhya S,Ganguly U,Chattar N,et al.Effect of SiN on perfor-mance and reliability of charge trap flash(CTF)under Fowler-Nordheim tunneling program/erase operation[J].IEEE Electron Device Lett,2009,30:171-173.
[15]Vianello E,Driussi F,et al.Explanation of the charge trapping properties of silicon nitride storage layers for NVMs——partⅠ:experimental evidences from physical and electrical characterization[J].IEEE Trans Electron Devices,2011,58:2483-2489.
[16]Kresse G,Furthmüller J.Efficient iterative s chemes for ab initio total-energy calculations using aplane-wave basis set[J].Canadian Metallurgical Quarterly,1996,54:11169-11186.
[17]Kresse G,Furthmüller J.Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set[J].Computational Materials Science,1996,6:15-50.
[18]Kresse G,Joubert D.From ultrasoft pseudopotentials to the projector augmented-wave method[J].Physical Review B,1999,59:1758-1775.
[19]Perdew J P,Burke K,Ernzerhof M.Generalized gradient approximation made simple[J].Physical Review Letters,1997,77:3865-3868.
[20]Whittle K R,Lumpkin G R,Ashbrook S E.Neutron diffraction and MAS NMR of cesium tungstate defect pyrochlores[J].Journal of Solid State Chemistry,2006,179:512-521.
[21]Robertson J,Ka Xiong,Falabretti B.Point defects in ZrO2high-k gate oxide[J].IEEE Transactions on Device and Materials Reliability,2005,5:84-89.
[22]Zheng J X,Ceder G,Maxisch T,et al.First-principles study of native point defects in hafnia and zirconia[J].Physical Review B,2007,75:104112-1-7.
[23]Gritsenko V A,Nekrashevich S S,et al.Electronic structure of memory traps in silicon nitride[J].Microelectron Engineering,2009,86:1866-1869.
[24]Edward S,et al.Improved grid-based algorithm for bader charge allocation[J].Journal of Computational Chemistry,2007,28:899-908.
[25]Balog M,Schieber M,Michman M,et al.Chemical vapor deposition and characterization of HfO2films from organo-hafnium compounds[J].Thin Solid Films,1977,41:247-259.
[26]Wang Y Q,Gao D Y,et al.Fast erasing and highly reliable MONOS type memory with HfO2 high-k trapping layer and Si3N4/SiO2tunneling stack[J].International Electron Devices Meeting,2006,1-4.