Study of Ni(Pt) germanosilicides formation on fully-strained Si 0.9 Ge 0.1 and Si0.899Ge 0.1 C0.001 by Raman Spectroscop
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Study of Ni(Pt) germanosilicides formation on fully-strained Si0.9Ge0.1 and Si0.899Ge0.1C0.001 by Raman Spectroscopy J. Y. Y. Chaw 1, K. L. Pey 1, P. S. Lee 2, D. Z. Chi 3 and J. P. Liu 4 School of Electrical & Electronic Engineering, Nanyang Avenue, Nanyang Technological University, Singapore 639798. 2 School of Materials Engineering, Nanyang Avenue, Nanyang Technological University, Singapore 639798. 3 Institute of Materials Research and Engineering, 3 Research Link, Singapore 117602. 4 Chartered Semiconductor Manufacturing Ltd., Woodlands Industrial Park D, Street 2, Singapore 738406. 1
ABSTRACT In this work, Raman spectroscopy was used to study the reaction of pure Ni and Ni(Pt 5 at. %) with fully-strained Si0.9Ge0.1 and Si0.899Ge0.1C0.001. With pure Ni, it was found that the incorporation of 0.1% C in the substrate resulted in out-diffusion of Ge from the germanosilicide film at a lower rapid thermal annealing (RTA) temperature compared to that of pure Ni on Si0.9Ge0.1. This Ge out-diffusion phenomenon is evident from the gradual shift in the NiSi1-wGew (w ≤ x) Raman peak from ~213 cm-1 to higher wavenumbers, closer to 217 cm-1 as reported for pure Ni/Si, indicating that Ge is being depleted from the film with increasing RTA temperatures. In addition, it was found that severe agglomeration of the germanosilicide film occurred at a lower RTA temperature for the Ni/Si0.899Ge0.1C0.001 system. This corresponds to the observations from the Raman spectra, where a sharp increase in the Si substrate peak at 520 cm-1 was observed, coupled with the appearance of the transverse acoustic (TA)-phonon peak of Si at 301 cm-1. When Pt was introduced into the Ni film, significant improvements were observed for the germanosilicide films on Si0.9Ge0.1 and Si0.899Ge0.1C0.001 substrates, both in terms of Ge outdiffusion and agglomeration. Initial findings show that the addition of Pt promotes the formation of the low resistivity mono-germanosilicide phase at temperatures as low as 300ºC.
INTRODUCTION Ni silicide is gradually replacing Co silicide in the self-aligned silicide (SALICIDE) process for the 90 technology node [1] and beyond. Some of its main advantages include the low temperature needed to form a low resistivity phase (about 400ºC to form NiSi compared to 750ºC for CoSi2). Ni silicide is also seen as the ideal candidate for advanced technologies; it forms a low resistivity solid solution with Si1-xGex substrates, a key feature for its integration into the latest strained Si and SiGe devices [2]. For strained Si1-xGex, C is sometimes incorporated for strain compensation to enable higher Ge concentration to be incorporated into the strained heterostructure [3]. Despite its many advantages, some key issues related to Ni silicides (and Ni germanosilicides) remain to be investigated. This includes agglomeration, NiSi (and NiSiGe) phase stability and Ge out-diffusion [4]. It has been previously demonstrated that alloying with Pt improves the morphological and phase stability of NiSi on Si [5]. For Ni on Si1-xGex subs
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