基于VO_2/TiO_2/FTO微结构的电压诱导相变存储器特性
|
摘要
相变存储器作为下一代具有竞争力的新型存储器,其基础和核心是相变存储介质。为了制备基于VO_2薄膜的非易失性相变存储器,首先采用等离子体增强化学气相沉积法在氟掺杂二氧化锡(FTO)导电玻璃衬底上沉积一层厚度为100 nm的TiO_2薄膜,再通过直流磁控溅射法制备VO_2薄膜,并在TiO_2/FTO复合薄膜上形成VO_2/TiO_2/FTO微结构,用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、四探针测试仪和半导体参数测试仪表征分析微结构的结晶和非易失性相变存储特性。结果表明,N_2和O_2的体积流量比为60∶40时,在TiO_2/FTO上可生长出晶向为<110>的高质量VO_2薄膜,在VO_2/TiO_2/FTO微结构两侧反复施加不同的脉冲电压,可观测到微结构具有非易失性相变存储特性,在67,68和69℃温度下的相变阈值电压分别为8.5,6.5和5.5 V,相比多层膜结构的相变阈值电压降低了约37%。
The phase change storage medium is the basis and core of the phase change memory,which is regarded as a competitive novel memory for the next generation. In order to fabricate the nonvolatile phase change memory based on the VO_2 thin film,a TiO_2 thin film with a thickness of 100 nm was deposited on the fluorine-doped tin oxide( FTO) conductive glass substrate by the plasma enhanced chemical vapor deposition firstly. Then the VO_2 thin film was prepared by the DC magnetron sputtering method,and VO_2/TiO_2/FTO microstructures were fabricated on TiO_2/FTO composite films. The microstructure crystallization and the characteristic of non-volatile phase change memory were characterized and analyzed by the X-ray diffraction( XRD),scanning electron microscope( SEM),four probes tester and semiconductor parameter tester. The results show that high-quality VO_2 thin films can be deposited on the TiO_2/FTO along the crystal orientation of <110> at 60 ∶ 40 volume flow ratio of N_2 and O_2. The characteristics of the non-volatile memory were observed when the different pulse voltages were applied toboth sides of the VO_2/TiO_2/FTO microstructure repeatedly. The phase change threshold voltages are8. 5,6. 5 and 5. 5 V when the ambient temperatures are 67,68 and 69 ℃ respectively,which is about37% lower than that of the multilayer film structure.
The phase change storage medium is the basis and core of the phase change memory,which is regarded as a competitive novel memory for the next generation. In order to fabricate the nonvolatile phase change memory based on the VO_2 thin film,a TiO_2 thin film with a thickness of 100 nm was deposited on the fluorine-doped tin oxide( FTO) conductive glass substrate by the plasma enhanced chemical vapor deposition firstly. Then the VO_2 thin film was prepared by the DC magnetron sputtering method,and VO_2/TiO_2/FTO microstructures were fabricated on TiO_2/FTO composite films. The microstructure crystallization and the characteristic of non-volatile phase change memory were characterized and analyzed by the X-ray diffraction( XRD),scanning electron microscope( SEM),four probes tester and semiconductor parameter tester. The results show that high-quality VO_2 thin films can be deposited on the TiO_2/FTO along the crystal orientation of <110> at 60 ∶ 40 volume flow ratio of N_2 and O_2. The characteristics of the non-volatile memory were observed when the different pulse voltages were applied toboth sides of the VO_2/TiO_2/FTO microstructure repeatedly. The phase change threshold voltages are8. 5,6. 5 and 5. 5 V when the ambient temperatures are 67,68 and 69 ℃ respectively,which is about37% lower than that of the multilayer film structure.
引文
[1]MARK H K,CHANG S K.After hard drives-what comesnext?[J].IEEE Transactions on Magnetics,2009,45(10):3406-3413.
[2]KANG M J,PARK T J,KWON Y W,et al.PRAM cell technology and characterization in 20 nm node size[C]∥Proceedings of IEEE International Electron Devices Meeting.New York,USA,2011:39-42.
[3]宋志棠.相变存储器与应用基础[M].1版.北京:科学出版社,2013:6-9.
[4]BRASSARD D,FOURMAUX S,JEAN J M,et al.Grain size effect on the semiconductor-metal phase transition characteristics of magnetron-sputtered VO2thin films[J].Applied Physics Letters,2005,87(5):051910-1-051910-3.
[5]NARAYAN J,BHOSLE V M.Phase transition and critical issues in structure-property correlations of vanadium oxide[J].Journal of Applied Physics,2006,100(10):103524-1-103524-6.
[6]KOO H,YOON S,KWON O J,et al.Effect of lattice misfit on the transition temperature of VO2thin film[J].Journal of Materials Science,2012,47(17):6397-6401.
[7]HU B B,DING Y,CHEN W,et al.External-strain induced insulating phase transition in VO2nanobeam and its application as flexible strain sensor[J].Advanced Materials,2010,22(45):5134-5139.
[8]熊瑛,文岐业,田伟,等.硅基二氧化钒相变薄膜电学特性研究[J].物理学报,2015,64(1):017102-1-017102-5.XIONG Y,WEN Q Y,TIAN W,et al.Researches on the electrical properties of vanadium oxide thin films on Si substrates[J].Acta Physica Sinica,2015,64(1):017102-1-017102-5(in Chinese).
[9]郝如龙,李毅,刘飞,等.基于FTO/VO2/FTO结构的VO2薄膜电压诱导相变光调制特[J].物理学报,2015,64(19):198101-1-198101-9.HAO R L,LI Y,LIU F,et al.Optical modulation characteristics of VO2thin film due to electric filed induced phase transition in the FTO/VO2/FTO structure[J].Acta Physica Sinica,2015,64(19):198101-1-198101-9(in Chinese).
[10]LEE M J,PARK Y D,SUH D S,et al.Two series oxide resistors applicable to high speed and high density nonvolatile memory[J].Advanced Materials,2007,19(22):3919-3923.
[11]DRISCOLL T,KIM H T,CHAE B G,et al.Memory metamaterials[J].Science,2009,325(5947):1518-1521.
[12]COY H,CABRERA R,SEPULVEDA N,et al.Optoelectronic and all-optical multiple memory states in vanadium dioxide[J].Journal of Applied Physics,2010,108(11):113115-1-113115-6.
[13]张宇明,李毅,孙若曦,等.紫外衍射微透镜阵列的设计与制备[J].光学技术,2012,38(3):263-267.ZHANG M Y,LI Y,ZHANG R X,et al.Design and fabrication of ultraviolet diffractive microlens array[J].Optical Technique,2012,38(3):263-267(in Chinese).
[14]颜家振,黄婉霞,李宁.VO2/Ti O2复合薄膜的结构和红外光学性质研究[J].红外与激光工程,2013,42(9):2485-2489.YAN J Z,HUANG W X,LI N.Structure and infrared optical properties of VO2/Ti O2multilayer film[J].Infrared and Laser Engineering,2013,42(9):2485-2489(in Chinese).
[15]ZHANG D P,YANG K,LI Y,et al.Employing Ti O2buffer layer to improve VO2film phase transition performance and infrared solar energy modulation ability[J].Journal of Alloys and Compounds,2016,684:719-725.
[16]REDNER S,MUELLER P R.Conductivity of a random directed-diode network near the percolation threshold[J].Physical Revies:B,1982,26(9):5293-5295.
[17]BALBERG I,BINENBAUM N.Direct determination of the conductivity exponent in directed percolation[J].Physical Revies:B,1986,33(3):2017-2019.
[18]宋婷婷,何捷,林理彬,等.氧化钒晶体的半导体至金属相变的理论研究[J].物理学报,2010,59(9):6480-6486.SONG T T,HE J,LIN L B,et al.The theoretical study of metal-insulator transition of VO2[J].Acta Physica Sinica,2010,59(9):6480-6486(in Chinese).
[2]KANG M J,PARK T J,KWON Y W,et al.PRAM cell technology and characterization in 20 nm node size[C]∥Proceedings of IEEE International Electron Devices Meeting.New York,USA,2011:39-42.
[3]宋志棠.相变存储器与应用基础[M].1版.北京:科学出版社,2013:6-9.
[4]BRASSARD D,FOURMAUX S,JEAN J M,et al.Grain size effect on the semiconductor-metal phase transition characteristics of magnetron-sputtered VO2thin films[J].Applied Physics Letters,2005,87(5):051910-1-051910-3.
[5]NARAYAN J,BHOSLE V M.Phase transition and critical issues in structure-property correlations of vanadium oxide[J].Journal of Applied Physics,2006,100(10):103524-1-103524-6.
[6]KOO H,YOON S,KWON O J,et al.Effect of lattice misfit on the transition temperature of VO2thin film[J].Journal of Materials Science,2012,47(17):6397-6401.
[7]HU B B,DING Y,CHEN W,et al.External-strain induced insulating phase transition in VO2nanobeam and its application as flexible strain sensor[J].Advanced Materials,2010,22(45):5134-5139.
[8]熊瑛,文岐业,田伟,等.硅基二氧化钒相变薄膜电学特性研究[J].物理学报,2015,64(1):017102-1-017102-5.XIONG Y,WEN Q Y,TIAN W,et al.Researches on the electrical properties of vanadium oxide thin films on Si substrates[J].Acta Physica Sinica,2015,64(1):017102-1-017102-5(in Chinese).
[9]郝如龙,李毅,刘飞,等.基于FTO/VO2/FTO结构的VO2薄膜电压诱导相变光调制特[J].物理学报,2015,64(19):198101-1-198101-9.HAO R L,LI Y,LIU F,et al.Optical modulation characteristics of VO2thin film due to electric filed induced phase transition in the FTO/VO2/FTO structure[J].Acta Physica Sinica,2015,64(19):198101-1-198101-9(in Chinese).
[10]LEE M J,PARK Y D,SUH D S,et al.Two series oxide resistors applicable to high speed and high density nonvolatile memory[J].Advanced Materials,2007,19(22):3919-3923.
[11]DRISCOLL T,KIM H T,CHAE B G,et al.Memory metamaterials[J].Science,2009,325(5947):1518-1521.
[12]COY H,CABRERA R,SEPULVEDA N,et al.Optoelectronic and all-optical multiple memory states in vanadium dioxide[J].Journal of Applied Physics,2010,108(11):113115-1-113115-6.
[13]张宇明,李毅,孙若曦,等.紫外衍射微透镜阵列的设计与制备[J].光学技术,2012,38(3):263-267.ZHANG M Y,LI Y,ZHANG R X,et al.Design and fabrication of ultraviolet diffractive microlens array[J].Optical Technique,2012,38(3):263-267(in Chinese).
[14]颜家振,黄婉霞,李宁.VO2/Ti O2复合薄膜的结构和红外光学性质研究[J].红外与激光工程,2013,42(9):2485-2489.YAN J Z,HUANG W X,LI N.Structure and infrared optical properties of VO2/Ti O2multilayer film[J].Infrared and Laser Engineering,2013,42(9):2485-2489(in Chinese).
[15]ZHANG D P,YANG K,LI Y,et al.Employing Ti O2buffer layer to improve VO2film phase transition performance and infrared solar energy modulation ability[J].Journal of Alloys and Compounds,2016,684:719-725.
[16]REDNER S,MUELLER P R.Conductivity of a random directed-diode network near the percolation threshold[J].Physical Revies:B,1982,26(9):5293-5295.
[17]BALBERG I,BINENBAUM N.Direct determination of the conductivity exponent in directed percolation[J].Physical Revies:B,1986,33(3):2017-2019.
[18]宋婷婷,何捷,林理彬,等.氧化钒晶体的半导体至金属相变的理论研究[J].物理学报,2010,59(9):6480-6486.SONG T T,HE J,LIN L B,et al.The theoretical study of metal-insulator transition of VO2[J].Acta Physica Sinica,2010,59(9):6480-6486(in Chinese).