Formation and microstructure of thin Ti silicide films for advanced technologies
We report on the solid-state reaction of thin PVD Ti films with in-situ doped Si & SiGe alloys using a combination of in-situ x-ray diffraction, sheet resistance, laser light scattering measurements and ex-situ x-ray pole figure analysis. Thin Ti films or thin bilayer films (Ni/Ti or NiPt/Ti) are found to be much more aligned with the underlying substrates. Millisecond laser anneals also lead to the introduction of strong in-plane texture.
Challenges of nickel silicidation in CMOS technologies
Display Omitted The evolution of CMOS technologies and of the silicidations techniques are described.A peculiar nickel monosilicide defect termed NiSi-Fang is detected and characterized.The NiSiGe formation is investigated on Si, SiGe materials and (100), (111) surfaces.A mechanism for the NiSi-Fang defect formation is proposed.This mechanism involves silicide formation, metal enrichment and metal diffusion. In this paper, we review some of the key challenges associated with the Ni silicidation process in the most recent CMOS technologies. The introduction of new materials (e.g. SiGe), and of non-planar architectures bring some important changes that require fundamental investigation from a material engineering perspective. Following a discussion of the device architecture and silicide evolution through the last CMOS generations, we focus our study on a very peculiar defect, termed NiSi-Fangs. We describe a mechanism for the defect formation, and present a detailed material analysis that supports this mechanism. We highlight some of the possible metal enrichment processes of the nickel monosilicide such as oxidation or various RIE (Reactive Ion Etching) plasma process, leading to a metal source available for defect formation. We also investigate the NiSi formation and re-formation silicidation differences between Si and SiGe materials, and between (100) and (111) orientations. Finally, we show that the thermal budgets post silicidation can lead to the formation of NiSi-Fangs if the structure and the processes are not optimized. Beyond the understanding of the defect and the discussion on the engineering solutions used to prevent its formation, the interest of this investigation also lies in the fundamental learning within the Ni-Pt-Si-Ge system and some additional perspective on Ni-based contacts to advanced microelectronic devices.
Sputter deposition and XPS analysis of nickel silicide thin films
Binary component Ni-Si films of different compositions are fabricated on AISI 304L stainless steels by means of ion-beam sputter (IBS) deposition. The compositions of the thin films and the chemical states of elements are analysed by means of X-ray photoelectron spectroscopy (XPS). The phase formation is studied and discussed in view of Pretorius' effective heat of formation (EHF) model. The proportions of the resulting phases can then be deduced. The electronic structure for the various compositions is also qualitatively investigated from the XPS valence band spectra, suggesting the bonding changes from predominating metallic to covalent bonding in Ni-Si systems when Si content increases.