原位XPS分析Al_2O_3作为势垒层的Er_2O_3/Si结构
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摘要
在超高真空条件下,通过脉冲激光沉积(PLD)技术制作了Er_2O_3/Al_2O_3/Si多层薄膜结构,原位条件下利用X射线光电子能谱(XPS)研究了Al_2O_3作为势垒层的Er_2O_3与Si界面的电子结构。XPS结果表明,Al_2O_3中Al的2p芯能级峰在低、高温退火前后没有变化;Er的4d芯能级峰来自于硅酸铒中的铒,并非全是本征氧化铒薄膜中的铒;衬底硅的芯能级峰在沉积Al_2O_3时没有变化,说明Al_2O_3薄膜从沉积到退火不参与任何反应,与Si界面很稳定;在沉积Er_2O_3薄膜和退火过程中,有硅化物生成,表明Er_2O_3与Si的界面不太稳定,但随着Al_2O_3薄膜厚度的增加,其硅化物中硅的峰强减弱,含量减少,说明势垒层很好地起到了阻挡扩散的作用。
The multi-layer films with Er_2O_3/Al_2O_3/Si structure were fabricated in the super-high vacuum by the pulsed laser deposition( PLD) technique. With the in-situ condition, the electronic structure of the interface between Si substrate and Er_2O_3 layer with Al_2O_3 barrier Layer was studied by the X-ray photoelectron spectroscopy( XPS). The XPS experimental result shows that the Al 2p core level peaks in Al_2O_3 layer have no changes before and after low and high temperature annealing process. The Er 4d core level peaks come from the erbium in erbium silicide,rather than that in the intrinsic erbium oxide film. There is no change in the core level peak of the substrate silicon when the Al_2O_3 is deposited.The results indicate that Al_2O_3 films don't participate in any reaction from deposition to annealing process and the interface between Al_2O_3 layer and Si is stable. The silicide is formed during the deposition of Er_2O_3 thin films and annealing process,indicating that the interface between Si substrate and Er_2O_3 is not stable. But the intensity and content of Si peaks in the silicide decrease with the increase of the thickness of the Al_2O_3 films. The results indicate that the barrier layer plays an important role in preventing the diffusion.
The multi-layer films with Er_2O_3/Al_2O_3/Si structure were fabricated in the super-high vacuum by the pulsed laser deposition( PLD) technique. With the in-situ condition, the electronic structure of the interface between Si substrate and Er_2O_3 layer with Al_2O_3 barrier Layer was studied by the X-ray photoelectron spectroscopy( XPS). The XPS experimental result shows that the Al 2p core level peaks in Al_2O_3 layer have no changes before and after low and high temperature annealing process. The Er 4d core level peaks come from the erbium in erbium silicide,rather than that in the intrinsic erbium oxide film. There is no change in the core level peak of the substrate silicon when the Al_2O_3 is deposited.The results indicate that Al_2O_3 films don't participate in any reaction from deposition to annealing process and the interface between Al_2O_3 layer and Si is stable. The silicide is formed during the deposition of Er_2O_3 thin films and annealing process,indicating that the interface between Si substrate and Er_2O_3 is not stable. But the intensity and content of Si peaks in the silicide decrease with the increase of the thickness of the Al_2O_3 films. The results indicate that the barrier layer plays an important role in preventing the diffusion.
引文
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[2]KOUDA M,SUZUKI T,KAKUSHIMA K,et al.Electrical properties of Ce O2/La2O3stacked gate dielectrics fabricated by chemical vapor deposition and atomic layer deposition[J].Japanese Journal of Applied Physics,2012,51(12R):121101-1-121101-5.
[3]CHEN S,ZHU Y Y,WU R,et al.Thermal stability of Er2O3thin films grown epitaxially on Si substrates[J].Journal of Applied Physics,2007,101(6):064106-1-064106-3.
[4]KUO C S,HSU J F,HUANG S W,et al.High-kAl2O3gate dielectrics prepared by oxidation of aluminum film in nitric acid followed by high-temperature annealing[J].IEEE Transactions on Electron Devices,2004,51(6):854-858.
[5]ZHU YY,FANG Z B,XU R.Optical constants of Er2O3-Al2O3films studied by spectroscopic ellipsometry[J].Journal of Rare Earths,2011,29(10):958-960.
[6]ZHU Y Y,FANG Z B,LIU Y S.Structural and optical properties of Er2O3films[J].Journal of Rare Earths,2010,28(5):752-755.
[7]FANG Z B,ZHU Y Y,CHEN W.Structure and electrical characterization of amorphous Er Si O films deposited by RF magnetron sputtering on Si(001)[J].Applied Physics:A,2011,102(3):695-698.
[8]LOSURDO M,GIANGREGORIO M M,CAPEZZUTO P,et al.Multifunctional nanocrystalline thin films of Er2O3∶interplay between nucleation kinetics and film characteristics[J].Advanced Functional Materials,2007,17(17):3607-3612.
[9]ZHU YY,XU R,CHEN S,et al.Epitaxial growth of Er2O3films on oxidized Si(111)and Si(001)substrates[J].Thin Solid Films,2006,508(1/2):86-89.
[10]KIM Y,LEE S M,PARK C S,et al.Substrate dependence on the optical properties of Al2O3films grown by atomic layer deposition[J].Applied Physics Letter,1997,71(25):3604-3606.
[11]PAIVASAARI J,NIINISTOJ,ARSTILA K,et al.High growth rate of erbium oxide thin films in atomic layer deposition from(Cp Me)3Er and water precursors[J].Chemical Vapor Deposition,2005,11(10):415-419.
[12]VANIN E V,GRISHIN A M,KHARTSEV S I,et al.Broadband photoluminescence from pulsed laser deposited Er2O3films[J].Journal of Luminescence,2006,121(2):256-258.
[13]WU D Q,YAO J C,ZHAO H S,et al.Leakage current mechanisms of ultrathin high-k Er2O3gate dielectric film[J].Journal of Semiconductors,2009,30(10):103003-1-103003-6.
[14]HUFNER S.Photoelectron spectroscopy:principles and applications[M].3rd ed.Berlin:Springer-Verlag,2013:11-13.
[15]MOULDER J F.Handbook of X-ray photoelectron spectroscopy[M].Eden Prairie:Perkin-Elmer Corp,1995:56-57.
[16]LEE W J,MA J W,BAE J M,et al.The diffusion of silicon atoms in stack structures of La2O3and Al2O3[J].Current Applied Physics,2013,13(4):633-639.