Detrimental impact of technological processes on BTI reliability of advanced high-K/metal gate stacks

A systematic study of mobility performances and Bias Temperature Instability (BTI) reliability was done on a large variety of advanced dielectric stacks. We clearly demonstrate that mobility performances and NBTI reliability are strongly correlated and that they are affected by the diffusion of nitrogen species N at the Si interface. Reducing the metal gate thickness favors the reduction of mobility degradations and NBTI, but, also strongly enhances PBTI, due to a complex set of reactions in the gate oxide. An optimum gate thickness must be found to obtain an acceptable trade off between device performance and reliability requirements.

[1]  Raghaw Rai,et al.  Compatibility of polycrystalline silicon gate deposition with HfO2 and Al2O3/HfO2 gate dielectrics , 2002 .

[2]  S.G. Park,et al.  The effects of TaN thickness and strained substrate on the performance and PBTI characteristics of poly-Si/TaN/HfSiON MOSFETs , 2004, IEDM Technical Digest. IEEE International Electron Devices Meeting, 2004..

[3]  Kikuo Yamabe,et al.  First-principles studies of the intrinsic effect of nitrogen atoms on reduction in gate leakage current through Hf-based high-k dielectrics , 2005 .

[4]  Byoung Hun Lee,et al.  Effects of ALD HfO2 thickness on charge trapping and mobility , 2005 .

[5]  John Robertson,et al.  Passivation of oxygen vacancy states in HfO2 by nitrogen , 2006 .

[6]  R. Chau,et al.  A 45nm Logic Technology with High-k+Metal Gate Transistors, Strained Silicon, 9 Cu Interconnect Layers, 193nm Dry Patterning, and 100% Pb-free Packaging , 2007, 2007 IEEE International Electron Devices Meeting.

[7]  X. Garros,et al.  Impact of TiN Metal gate on NBTI assessed by interface states and fast transient effect characterization , 2007, 2007 IEEE International Electron Devices Meeting.

[8]  X. Garros,et al.  Guidelines to improve mobility performances and BTI reliability of advanced high-k/metal gate stacks , 2008, 2008 Symposium on VLSI Technology.

[9]  M. Perego,et al.  Interface Study in a "Metal / High-k" Gate Stack: Tantalum Nitride on Hafnium Oxide , 2008 .

[10]  X. Garros,et al.  Impact of crystallinity of High-k oxides on Vt instabilities of NMOS devices assessed by physical and electrical measurements , 2008, 2008 IEEE International Reliability Physics Symposium.