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With the transition to ≤28-nm CMOS technology nodes, the surface analytical challenges with regard to steadily decreasing dimensions and still growing materials options raise the demand of high performing surface analysis techniques. Characterization of ultrathin films and multilayer stacks, especially in high-k metal gate stacks, by means of low energy ion scattering spectroscopy (LEIS) with its monolayer sensitivity has been established as a very useful analysis technique next to Auger electron spectroscopy, X-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry. Questions regarding film nucleation, growth, coverage, and diffusion can be answered, thereby enabling those processes to be controlled appropriately. In this work, growth studies of ALD HfO2 and TiN are shown, as well as film thickness determination based on surface spectra. PVD aluminum and lanthanum, acting as work function metals on the gate oxide, were deposited, and their film formation and closure were investigated. Further application fields of LEIS have emerged from the characterization of in-die features on patterned wafers. As presented on test arrays, it is possible to detect material deep in trenches. This is an advantage if residues need to be identified after etch or clean processes.

The time dependent dielectric breakdown (TDDB) in copper/ultra-low-k on-chip interconnect stacks of integrated circuits has become one of the most critical reliability concerns in recent years. In this paper, a novel experimental in situ microscopy approach using transmission X-ray microscopy (TXM) and scanning transmission electron microscopy (STEM) is proposed to study TDDB degradation and failure mechanisms. It combines electrical testing and imaging techniques. Low-dose bright field (BF) STEM inserting a small condenser aperture is chosen to reduce the beam damage of the dielectric material, while the electron spectroscopic imaging technique is used for the chemical analysis to detect the migration path of Cu atoms. This new experimental approach will contribute to an improved understanding of the TDDB effect.

A major challenge for the application of strain engineering to enhance the performance of electronic devices is the quantification of strain on the nanoscale. Besides other techniques (Raman spectroscopy, X-ray diffraction) electron beam techniques allow strain analyses with a spatial resolution of a few nanometers and a reasonable strain sensitivity of 1x10 -3 (relative to the lattice constant of silicon). In the present work, we address practical issues in the application of nano-beam electron diffraction (NBED) to probe the strain in strained silicon layers and sub-100 nm structures. The investigated specimens were prepared on biaxially tensile strained silicon-on- insulator substrates with an initial strain of = 0.6% or 0.8%. Results of the NBED experiments were compared to data obtained by other strain measurement techniques; amongst them the strain mapping by peak-pairs analysis of high-angle annular dark field (HAADF) images was especially considered. NBED can be easily performed by use of STEM with a small aperture of the 2 nd condenser lens in the micro- or nanoprobe mode. The NBED principle consists in illuminating a nanometer-sized area of the specimen (being in zone axis orientation) with a nearly parallel electron beam and acquiring series of diffraction patterns at points along previously defined lines. The strain components of interest are generally calculated using a dedicated software package which is based on procedures for the analysis of electron diffraction patterns. The spatial resolution of NBED is determined by the beam diameter to a few nanometers. The

The thermal stability of a SiNx passivation layer and its influence on the annealing behavior of an amorphous Ta73Si27 diffusion barrier deposited between copper and SiO2 were analyzed by X-ray diffraction, glow discharge optical emission spectroscopy, Auger electron spectroscopy, scanning electron microscopy, and transmission electron microscopy. During heat treatment at a temperature Tan = 500 °C, diffusion of Cu atoms out of the Cu metallization into the SiNx passivation occurs. The Cu diffusion intensifies with increasing annealing temperature and annealing time and seems to be a necessary precondition for a defect formation process observed within the Cu metallization. Depending on the chemical composition of the SiNx/Cu interface, voids in the μm-range can be formed within the Cu film. Compared to an unpassivated sample, heat treatment leads to a reduced diffusion of Ta atoms from the barrier through the copper into the SiNx/Cu interface. The barrier crystallization process into Ta5Si3 occurring during annealing at Tan = 600 °C is principally not affected by the presence of a SiNx passivation. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The influence of Ni-content of austenitic stainless steels on the SCC crack growth mechanism in chloride solutions at elevated temperatures is discussed, based on crack tip characterization of corrosive cracks by means of Transmission Electron Microscopy, Samples of stainless steels AISI 321 and INCOLOY 800 were analyzed. The results indicate a cracking process highly influenced by hydrogen, which is produced by the cathodic reaction of the corrosion process inside the crack.The effect of corrosive hydrogen on the cracking process depends on the stacking fault energy and thus on the Ni-content of the steel. There is also an influence of Ni-content on the diffusion coefficients of hydrogen in the austenitic lattic, determining the formation of hydrogen up to a critical concentration in the crack tip region