Breakdown and degradation of ultrathin Hf-based (HfO2)x (SiO2)1-x gate oxide films

Ultrathin films of hafnium oxide (HfO2) and hafnium silicate (HfO2)x(SiO2)1−x gate stacks (∼3nm) have been subjected to localized electrical stress with a conductive atomic force microscope (C-AFM) in ultrahigh vacuum. The nanoscale current-voltage (I-V) characteristics, prebreakdown temperature dependent I-V measurements on large area metal-insulator-semiconductor capacitors, postbreakdown (BD) topography, current maps, and AFM tip-surface contact force are used to interpret the progressive degradation of the oxide under electrical stress. For the pre-BD phase, trap-assisted tunneling and Fowler–Nordheim tunneling were found to be dominant current transport mechanisms in Hf-based gate stacks contributing to oxide leakage current. For the post-BD phase, an overall effect of barrier limited tunneling current on the charge propagation is confirmed and related to post-BD conductivity features observed by constant voltage scanning. A critical trap density required to trigger a BD event of the ultrathin (HfO2)...

[1]  Yoshitaka Tsunashima,et al.  Effects of Nitrogen Concentration and Post-treatment on Reliability of HfSiON Gate Dielectrics in Inversion States , 2005 .

[2]  Constantin Papadas,et al.  Temperature dependence of the Fowler–Nordheim current in metal‐oxide‐degenerate semiconductor structures , 1995 .

[3]  S. Lombardo,et al.  Intrinsic dielectric breakdown of ultra-thin gate oxides , 2001 .

[4]  Octavian Buiu,et al.  Current transport mechanisms in (HfO2)x(SiO2) 1-x /SiO2gate stacks , 2007 .

[5]  Marc Porti,et al.  Systematic characterization of soft- and hard-breakdown spots using techniques with nanometer resolution , 2007 .

[6]  Emission properties of polycrystalline diamond-coated silicon emitters , 1998 .

[7]  Homogeneity improvements in the dielectric characteristics of HfSiON films by nitridation , 2007 .

[8]  You-Lin Wu,et al.  Two-trap-assisted tunneling model for post-breakdown I-V characteristics in ultrathin silicon dioxide , 2006 .

[9]  Jordi Suñé,et al.  Soft Breakdown in Ultrathin SiO2 Layers: the Conduction Problem from a New Point of View , 1999 .

[10]  Bruno Ricco,et al.  Modeling and simulation of stress-induced leakage current in ultrathin SiO/sub 2/ films , 1998 .

[11]  Hideki Takeuchi,et al.  Scaling limits of hafnium–silicate films for gate-dielectric applications , 2003 .

[12]  Salvatore Lombardo,et al.  Degradation and hard breakdown transient of thin gate oxides in metal–SiO2–Si capacitors: Dependence on oxide thickness , 1999 .

[13]  Electron photoemission from conducting nitrides (TiNx,TaNx) into SiO2 and HfO2 , 2005 .

[14]  Wilfried Vandervorst,et al.  Evaluation of trap creation and charging in thin SiO2 using both SCM and C-AFM , 2007 .

[15]  T. W. Hughes,et al.  Properties of high-voltage stress generated traps in thin silicon oxide , 1996 .

[16]  Yuan Chen,et al.  Detailed study and projection of hard breakdown evolution in ultra-thin gate oxides , 2005, Microelectron. Reliab..

[17]  John H. Davis,et al.  Noncontact scanning probe microscope potentiometry of surface charge patches: Origin and interpretation of time-dependent signals , 1998 .

[18]  B. Hamilton,et al.  Reliability nano-characterization of thin SiO2 and HfSixOy/SiO 2 gate stacks , 2007 .

[19]  B. Riccò,et al.  High-field-induced degradation in ultra-thin SiO/sub 2/ films , 1988 .

[20]  Wilfried Vandervorst,et al.  Conductive atomic force microscopy studies of thin SiO2 layer degradation , 2006 .

[21]  M. Caymax,et al.  Composition and Growth Kinetics of the Interfacial Layer for MOCVD HfO2 Layers on Si Substrates , 2004 .

[22]  Fu-Chien Chiu,et al.  Interface characterization and carrier transportation in metal/HfO2/silicon structure , 2006 .

[23]  Steve Hall,et al.  Electrical and structural properties of hafnium silicate thin films , 2007, Microelectron. Reliab..