The reaction of Ni with Si-Ge: An overview and some new considerations
2005 (English)In: Proc. Electrochem. Soc., 2005, 597-611 p.Conference paper (Refereed)
The reactive phase formation upon annealing Ni films deposited on Si-Ge alloy substrates has become an attractive research subject as a result of two parallel rapid developments in Si technology: (1) the down-scaling of CMOS technology to the sub-50 nm regime and (2) the incorporation of Ge in standard Si-MOSFET for performance enhancement. Recent publications concern the phase formation and stability of the formed Ni(Si-Ge)p (p=0.5, 1 or 2), microstructure and morphological instability of the grown Ni(Si-Ge) (p=1) layers, and electrical behavior of the transition region at the Ni(Si-Ge)/Si-Ge interface. In the present work, those aspects are further discussed. Assumptions and simplifications were made when calculating the approximate phase diagram for the Ni-Si-Ge ternary system. Several of those assumptions are discussed in greater details in this work. An attempt to estimate the solid solubility of Ge in NiSi2 is presented, which yields a value less than 1 at.%. The role of Ge in the morphological instability at the interfacial region between Ni(Si-Ge)p and Si-Ge is discussed in the light of recently published experimental data. Incorporating further elements such as Pt or C could lead to improved interface morphology. The potential consequences of such additions include increased process complexity and different kinds of instabilities. Lateral encroachment of Ni(Si-Ge)p in contact windows has been observed, which is caused by the fast Ni diffusion (faster than Si and Ge) during the growth of the monosilicide or germanosilicide. These effects can be catastrophic to the unaware and careful process design is needed to control the lateral growth. The reported large thermal expansion coefficients of NiSi could be the cause for reliability problems such as void formation between the formed NiSi and the Si channel. The fiber texture development observed in the grown NiSi1-xGex in combination with the anisotropy of the thermal expansion coefficients of NiSi are discussed as a likely engineering approach to minimizing void formation.
Place, publisher, year, edition, pages
2005. 597-611 p.
, Proceedings - Electrochemical Society, PV 2005-05
Annealing, Microstructure, Morphology, MOSFET devices, Nickel, Phase diagrams, Ternary systems, Textures, Interface morphology, Reactive phase formation, Void formation, Semiconducting silicon
Electrical Engineering, Electronic Engineering, Information Engineering
IdentifiersURN: urn:nbn:se:kth:diva-156482ScopusID: 2-s2.0-31944449377OAI: oai:DiVA.org:kth-156482DiVA: diva2:768507
207th ECS Meeting, 16-20 May 2005, Quebec
QC 201412042014-12-042014-11-282014-12-04Bibliographically approved