Work function Φ is a crucial factor in improving the high-k/metal gate stack. Here we present a systematic study of the strain-dependent work function on the Pt metal gate (100) surface using the first-principles calculation. We find that the compressive strain increases Φ, while the tensile strain decreases its value, with the biaxial strain leading to the maximum change of Φ. We identify the mechanism of Φ modification by analyzing the effect of strain on the bulk electronic structure and surface dipole. Finally, we propose a canonical strain-Φ relationship, which provides a design principle for the work function tuning with strain.
Evolution of stresses developing in Cu thin films during and after deposition by thermal evaporation in UHV system is studied. Thin films were deposited on 100 µm thick Si substrate at room temperature. Deposition rates for the films were changed between 0.2 Å/s and 2.0 Å/s, while the total thickness was changed from 7.7 nm to 155 nm. Deformation analysis of crystalline lattice and microstructure was performed by x-ray diffraction measurements (θ-2θ scans, "sin 2 ψ" method). The surface morphology of film was studied by atomic force microscopy. The average stress in the films was determined by measuring the radius of curvature of samples. For thin films three stages of stress evolution (compressive, tensile and compressive) were we distinguished. This behavior is characteristic for materials with a Volmer-Weber mode. A three-dimensional molecular dynamics technique was applied for simulating the stress calculation during thin film growth. The results obtained from the simulation are consistent with the experimental results.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.