薄膜晶体管中高性能HfO_2的低温制备研究
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摘要
采用电子束蒸镀在ITO上沉积Hf O2,研究了不同退火工艺对其电学性能的影响。当450℃时O2退火,Hf O2的漏电迅速增加,通过X射线衍射发现Hf O2有单斜相等结晶生成。450℃下N2退火,Hf O2结构则没有明显晶体和晶界结构,且N2气氛退火的Hf O2漏电约为O2气氛退火的1/10。
The Hf O_2 coating,synthesized by electron beam evaporation and annealed in O_2 or N_2atmosphere on the ITO-coated glass substrate was used as the grid dielectric material in fabrication of thin film transistor( TFT). The influence of the thickness and annealing atmosphere,on the phase-structures and electrical properties of the Hf O2 coatings was investigated with X-ray diffraction. The results show that the annealing strongly affects the microstructures and electrical properties. For example,annealed at 450 ℃ for 30 min in O_2,the leakage current sharply increased,possibly because the boundaries between the monoclinic,cubic and orthorhombic-phased grains resulted in the formation of leakage channel. In contrast,an annealing in N_2 inhabited such grain-boundary formation and crystallization,reducing the leakage current by more than 10 times. We suggest that the Hf O_2 film be a promising TFT grid material because of its high dielectric constant and low leakage current.
The Hf O_2 coating,synthesized by electron beam evaporation and annealed in O_2 or N_2atmosphere on the ITO-coated glass substrate was used as the grid dielectric material in fabrication of thin film transistor( TFT). The influence of the thickness and annealing atmosphere,on the phase-structures and electrical properties of the Hf O2 coatings was investigated with X-ray diffraction. The results show that the annealing strongly affects the microstructures and electrical properties. For example,annealed at 450 ℃ for 30 min in O_2,the leakage current sharply increased,possibly because the boundaries between the monoclinic,cubic and orthorhombic-phased grains resulted in the formation of leakage channel. In contrast,an annealing in N_2 inhabited such grain-boundary formation and crystallization,reducing the leakage current by more than 10 times. We suggest that the Hf O_2 film be a promising TFT grid material because of its high dielectric constant and low leakage current.
引文
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[2]Kim B,Franklin A,Nuckolls C,et al.Achieving Low-Voltage Thin-Film Transistors Using Carbon Nanotubes[J].Applied Physics Letters,2014,105(6):63111
[3]Choi J H,Mao Y,Chang J P.Development of Hafnium Based High-k Materials—A Review[J].Materials Science and Engineering:R:Reports,2011,72(6):97-136
[4]Ribes G,Mitard J,Denais M,et al.Review on High-k Dielectrics Reliability Issues[J].Ieee Transactions On Device and Materials Reliability,2005,5(1):5-19
[5]Pan T,Chen C,Liu J,et al.Electrical and Reliability Characteristics of High-k Ho Ti O3α-In Ga Zn O Thin-Film Transistors[J].IEEE Electron Device Letters,2014,35(1):66-68
[6]Yim K,Yong Y,Lee J,et al.Novel High-k Dielectrics for Next-Generation Electronic Devices Screened by Automated ab Initio Calculations[J].Npg Asia Materials,2015,7(6):e190
[7]Robertson J,Wallace R M.High-k Materials and Metal Gates for CMOS Applications[J].Materials Science and Engineering:R:Reports,2015,88:1-41
[8]Cheynet M C,Pokrant S,Tichelaar F D,et al.Crystal Structure and Band Gap Determination of Hf O2Thin Films[J].Journal of Applied Physics,2007,101(5):54101
[9]Robertson J.High Dielectric Constant Oxides[J].The European Physical Journal Applied Physics,2004,28(3):265-291
[10]Xiong K,Robertson J,Gibson M C,et al.Defect Energy Levels in Hf O2High-Dielectric-Constant Gate Oxide[J].Applied Physics Letters,2005,87(18):183505
[11]Kim B,Franklin A,Nuckolls C,et al.Achieving LowVoltage Thin-Film Transistors Using Carbon Nanotubes[J].Applied Physics Letters,2014,105(6):63111
[12]Li H,Guo Y,Robertson J.Dopant Compensation in Hf O2and Other High K Oxides[J].Applied Physics Letters,2014,104(19):192904
[13]Kim D Y,Kang J,Chang K J.Impact of Si Impurities in Hf O2:Threshold Voltage Problems in Poly-Si/Hf O2Gate Stacks[J].Journal of the Korean Physical Society,2006,48(6):1628-1632
[14]Onishi K,Kang C S,Choi R,et al.Improvement of Surface Carrier Mobility of Hf O2MOSFETs by High-Temperature Forming Gas Annealing[J].IEEE Transactions On Electron Devices,2003,50(2):384-390
[15]Cho M J,Park H B,Park J,et al.Thermal Annealing Effects on the Structural and Electrical Properties of Hf O2/Al2O3Gate Dielectric Stacks Grown by Atomic Layer Deposition on Si Substrates[J].Journal of Applied Physics,2003,94(4):2563-2571
[16]Grüger H,Kunath C,Kurth E,et al.High Quality r.f.Sputtered Metal Oxides(Ta2O5,Hf O2)and Their Properties After Annealing[J].Thin Solid Films,2004,447-448:509-515
[17]Zhao X,Vanderbilt D.First-Principles Study of Structural,Vibrational,and Lattice Dielectric Properties of Hafnium Oxide[J].Physical Review,2002,B65(23):233106
[18]Rieger T,Jorres T,Vogel J,et al.Crystallization of Hf O2in In As/Hf O2Core-Shell Nanowires[J].Nanotechnology,2014,25(40):405701
[19]Hildebrandt E,Kurian J,Muüller M M,et al.Controlled Oxygen Vacancy Induced P-type Conductivity in Hf O2-x Thin Films[J].Applied Physics Letters,2011,99(11):112902
[20]Yuqiong C,Zongliang H,Yulong H,et al.Investigation of Charge Loss Characteristics of Hf O2Annealed in N2or O2Ambient[J].Journal of Semiconductors,2014,35(8):83004
[21]Zhang Y,Shao Y Y,Lu X B,et al.Defect States and Charge Trapping Characteristics of Hf O2Films for High Performance Nonvolatile Memory Applications[J].Applied Physics Letters,2014,105(17):172902
[22]Iglesias V,Lanza M,Zhang K,et al.Degradation of Polycrystalline Hf O2-Based Gate Dielectrics Under Nanoscale Electrical Stress[J].Applied Physics Letters,2011,99(10):103510