High-k HfO2-Ta2O5 mixed layers: Electrical characteristics and mechanisms of conductivity

Electrical properties of mixed HfO"2-Ta"2O"5 films (10;15nm) deposited by rf sputtering on Si have been studied from the view point of their applications as high-k layers, by standard capacitance-voltage and temperature dependent current-voltage characteristics. The effect of HfO"2 addition to the Ta"2O"5 is thickness dependent and the thicker layers exhibit advantages over the pure Ta"2O"5 (higher dielectric constant, enhanced charge storage density and improved interface quality). The process of HfO"2 and Ta"2O"5 mixing introduces negative oxide charge, tends to creates shallow bulk traps and modifies the dominant conduction mechanisms in the stack capacitors as compared to the Ta"2O"5-based one (a contribution of tunneling processes through traps located below the conduction band of mixed layers to the leakage current in the HfO"2-Ta"2O"5 stacks is observed). The traps involved in both Poole-Frenkel and tunneling processes are identified.

[1]  Yue Kuo,et al.  Hafnium-Doped Tantalum Oxide High-k Gate Dielectrics , 2006 .

[2]  W. Lau,et al.  Mechanism of leakage current reduction of tantalum oxide capacitors by titanium doping , 2007 .

[3]  Guido Groeseneken,et al.  Electrical properties of high-κ gate dielectrics: Challenges, current issues, and possible solutions , 2006 .

[4]  E. Atanassova,et al.  High temperature-induced crystallization in tantalum pentoxide layers and its influence on the electrical properties , 2003 .

[5]  Ninoslav Stojadinovic,et al.  Degradation behavior of Ta2O5 stacks and its dependence on the gate electrode , 2008, Microelectron. Reliab..

[6]  H. Fukuda,et al.  Effects of additive elements on improvement of the dielectric properties of Ta2O5 films formed by metalorganic decomposition , 2003 .

[8]  R. Wallace,et al.  High-κ gate dielectrics: Current status and materials properties considerations , 2001 .

[9]  K. Kukli,et al.  Conductance transient, capacitance–voltage and deep-level transient spectroscopy characterization of atomic layer deposited hafnium and zirconium oxide thin films , 2003 .

[10]  E. Atanassova,et al.  Electrical characteristics of Ti-doped Ta2O5 stacked capacitors , 2008 .

[11]  Robert Joseph Cava,et al.  Dielectric properties of Ta2O5–ZrO2 polycrystalline ceramics , 1996 .

[12]  Albena Paskaleva,et al.  Challenges of Ta2O5 as High-k Dielectric for Nanoscale DRAMs , 2006, 2006 25th International Conference on Microelectronics.

[13]  K. Onishi,et al.  Electrical characteristics of highly reliable ultrathin hafnium oxide gate dielectric , 2000, IEEE Electron Device Letters.

[14]  N. Novkovski,et al.  Effects of the metal gate on the stress-induced traps in Ta2O5/SiO2 stacks , 2008, Microelectron. Reliab..

[15]  Y. Lan,et al.  Manipulation of Tunneling Frequencies Using Magnetic Fields for Resonant Tunneling Effects of Surface Plasmons , 2007 .

[16]  Elena Atanassova,et al.  Electrical characteristics of Ta2O5 based capacitors with different gate electrodes , 2006 .

[17]  Elena Atanassova,et al.  Thin RF sputtered and thermal Ta2O5 on Si for high density DRAM application , 1999 .

[18]  A. Stesmans,et al.  Trap-assisted tunneling in high permittivity gate dielectric stacks , 2000 .

[19]  Fred P. Klemens,et al.  Multi-component high-K gate dielectrics for the silicon industry , 2001 .

[20]  Y. Taga,et al.  Effects of additive elements on electrical properties of tantalum oxide films , 1994 .

[21]  G. Lucovsky,et al.  A molecular orbital model for the electronic structure of transition metal atoms in silicate and aluminate alloys , 2001 .

[22]  E. Atanassova,et al.  Beneficial effect of post-metallization H2 annealing on Ta2O5 stack capacitors , 2006 .

[23]  E. Cartier,et al.  Ultrathin high-K metal oxides on silicon: processing, characterization and integration issues , 2001 .

[24]  Y. Kuo,et al.  Electrical and Physical Characterization of Zirconium-Doped Tantalum Oxide Thin Films , 2004 .

[25]  E. Atanassova,et al.  Conduction mechanisms and reliability of thermal Ta2O5–Si structures and the effect of the gate electrode , 2005 .

[26]  N. Novkovski,et al.  Constant current stress of Ti-doped Ta2O5 on nitrided Si , 2009 .

[27]  S. Jakschik,et al.  Transport mechanisms in atomic-layer-deposited Al2O3 dielectrics , 2004 .

[28]  E. Atanassova,et al.  Impact of Si substrate nitridation on electrical characteristics of Ta2O5 stack capacitors , 2007 .

[29]  Heung-Jae Cho,et al.  Electrical characteristics and thermal stability of n+ polycrystalline- Si/ZrO2/SiO2/Si metal–oxide–semiconductor capacitors , 2002 .

[30]  E. Atanassova,et al.  Composition of Ta2O5 stacked films on N2O- and NH3-nitrided Si , 2006 .

[31]  M. Houssa.  High k Gate Dielectrics , 2003 .

[32]  J. Kim,et al.  Current transport in metal/hafnium oxide/silicon structure , 2002, IEEE Electron Device Letters.

[33]  Ignaz Eisele,et al.  A model for multistep trap-assisted tunneling in thin high-k dielectrics , 2005 .