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Depth Profiling of La2O3OHfO2 Stacked Dielectrics for Nanoelectronic Device Applications H. N. Alshareef, S. Mure, P. Majhi, and M. A. Quevedo-Lopez Materials Science and Engineering, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia Kobe Steel Ltd., Machinery and Engineering Company, Takasago 676-8670, Japan INTEL Assignee to SEMATECH, Austin, Texas 78748, USA Materials Science and Engineering, University of Texas at Dallas, Richardson, Texas 75080, USA

In this article, ytterbium (Yb) incorporation into NiGe is proposed to improve the thermal stability of Ni germanide for high-performance Ge metal-oxide-semiconductor field-effect transistors (Ge MOSFETs). The Yb/Ni/TiN structure shows suppression of NiGe agglomeration and better surface morphology than the Ni/TiN structure after a postgermanidation annealing of up to 550°C for 30 min. It is notable that Yb atoms distribute uniformly at the top region of NiGe. NiGe agglomeration was retarded by Yb incorporation, and the thermal stability of NiGe was therefore improved.

Nitrogen implantation prior to nickel silicidation is shown to result in a modified Schottky barrier height at the NiSi/Si(001) interface. Passivation of dangling bonds at the NiSi/Si interface to de-pin the Fermi level, axiotaxy texture, and strain-induced barrier lowering are determined to be the main mechanisms for the barrier-height modification. Significant barrier-height reduction (by as much as 0.37 eV) can be achieved on n-type silicon. However, the resistivity of nickel silicide increases significantly beyond a critical nitrogen-implant dose (1 X 10 15 cm -2 ).

In this article, thermally stable Ni germanide using palladium (Pd) incorporation is proposed for high performance germanium metal-oxide-semiconductor field-effect transistors, and a microstructural analysis of the Ni germanide is performed in depth. The proposed Pd/Ni/TiN structure exhibited a stable sheet resistance despite high temperature postgermanidation annealing of up to 500°C for 30 min. The cause of the improved thermal stability is determined to be caused by the pileup of Pd atoms at the bottom region of NiGe, which resulted in the retardation of NiGe agglomeration by the formation of PdGe or NiPdGe there.

Phase separation of Ni germanide due to the penetration of Ni atoms from Ni germanide in the Ge layer into the bottom Si substrate is reported. The orthorhombic-structure Ni germanide is formed in a Ge-on-Si substrate, which is promising for high-performance Ge p-channel metal-oxide-semiconductor field effect transistor (PMOSFETs). However, the Ni penetration and resulting Ni-rich Ni silicide formation happens when the Ni germanide becomes thick enough to touch the bottom Si substrate. The phase separation or Ni penetration observed in this work is believed to be due to the lower heat of formation of NiSi than NiGe. The Ni penetration must be controlled in fabricating source/drain regions for high-mobility Ge-on-Si MOSFETs.