A.K. Balamurugan

Surface roughness and interface diffusion studies on thin Mo and W films and Mo/Si and W/Si interfaces

Single layers of Mo and W thin films and Mo/Si/Mo and W/Si/W tri-layers have been deposited by r.f. sputtering on c-Si substrates as precursor to the fabrication of Mo/Si and W/Si multilayer X-ray mirrors. The single layer thin films have been characterized primarily by phase modulated spectroscopic ellipsometry (SE) and information have been derived regarding the thickness and volume fraction of voids present in the layers. The results obtained by fitting the SE data have been verified by complementary techniques, viz. grazing-incidence X-ray reflectivity, Rutherford back-scattering and atomic force microscopy. With the optimized values of the sputtering parameters, Mo/Si/Mo and W/Si/W tri-layer structures have been deposited on c-Si substrates and have been characterized by secondary ion mass spectrometry (SIMS) technique using sputtering by a Cs þ ion source. The depth profile data obtained from the SIMS measurements have been analyzed to get the inter-diffusion at the metal‐ Si interfaces. Efforts have been given to correlate the interface diffusion at the interfaces to the thickness of the surface layers of the metal films. # 2003 Elsevier Science B.V. All rights reserved.

Characterization of RF Sputter-Deposited Ultra Thin PZT Films and Its Interface With Substrate

Lead Zirconate Titanate [Pb(Zr,Ti)O3, PZT] thin films have been extensively studied due to their possible applications in ferroelectric and piezoelectric devices. This work deals with the synthesis and characterization of ultra thin PZT films of thickness ∼100 nm deposited on Si/SiO2/TiO2/Pt(111) by RF Magnetron Sputtering under optimized deposition and post-annealing conditions. Various techniques like XRD, XPS, SIMS, SEM and TEM, have been employed to characterize the film nanostructure and the interface quality in the post-annealed films. Though the XRD results showed the formation of ∼87 vol% perovskite phase with 111 orientation, the films failed to show good electrical and ferroelectric properties. In XPS study of annealed PZT films, Pb was found to exist in both oxidised and metallic states. Both SIMS depth profiling and STEM-EDX line profile results showed that there is an enrichment of Pb along the PZT/Pt interface. This suggests interdiffusion of the elements in the film during post-annealing. It is concluded that interdiffusion of the chemical species during annealing results in Pb enrichment at the film substrate interface. In addition, the presence of ∼13% non-ferroelectric pyrochlore phase as well as some amount of Pb species present in metallic state further degrades the film quality.

Mass spectral analysis and quantification of Secondary Ion Mass Spectrometry data

Abstract This work highlights the possibility of improving the quantification aspect of Cs-complex ions in SIMS (Secondary Ion Mass Spectrometry), by combining the intensities of all possible Cs complexes. Identification of all possible Cs complexes requires quantitative analysis of mass spectrum from the material of interest. The important steps of this mass spectral analysis include constructing fingerprint mass spectra of the constituent species from the table of isotopic abundances of elements, constructing the system(s) of linear equations to get the intensities of those species, solving them, evaluating the solutions and implementing a regularization procedure when required. These steps are comprehensively described and the results of their application on a SIMS mass spectrum obtained from D9 steel are presented. It is demonstrated that results from the summation procedure, which covers entire range of sputtered clusters, are superior to results from single Cs-complex per element. The result of operating a regularization process in solving a mass spectrum from an SS316LN steel specimen is provided to demonstrate the necessity of regularization.

Structural and nano-mechanical characterization of TiN / Ti 1−x Al x N multilayered thin films

Nanostructured multilayers have high interface area densities along with other factors such as periodicity, single layer thickness, sharpness, in general lead to improved mechanical properties. In this study, we have selected a combination of two metallic hard materials, such as cubic TiN and metastable cubic TiAlN sub-layers to synthesize a periodic multilayer thin films. Advantage of TiAlN as a sub-layer is the stability against oxidation due to the formation of dense Al2O3, which prevents further oxidation. These periodic TiN/TiAlN multilayers were synthesized by reactive magnetron co-sputtering technique on SS 304 LN substrates with TiN as a starting sub-layer and TiAlN as next with bi-layer thicknesses 7 nm to 60 nm. GIXRD results confirm the formation of metastable TiAlN with NaCl structure which is similar to TiN with a shift in the peak position. The individual layers were resolved by X-TEM and Secondary Ion Mass Spectroscopy to understand the architecture. Depth sensing nanoindentation was used to study the surface hardness which clearly explains the reverse Hall-Petch relationship (change in the periodicity). The maximum surface hardness of 34 GPa was obtained for a bi-layer thickness of 30 nm.