Atom insertion into grain boundaries and stress generation in physically vapor deposited films

Abstract

We present evidence for compressive stress generation via atom insertion into grain boundaries in polycrystalline Mo thin films deposited using energetic vapor fluxes (&lt;∼120 eV). Intrinsic stress magnitudes between −3 and +0.2 GPa are obtained with a nearly constant stress-free lattice parameter marginally larger (0.12%) than that of bulk Mo. This, together with a correlation between large compressive film stresses and high film densities, implies that the compressive stress is not caused by defect creation in the grains but by grain boundary densification. Two mechanisms for diffusion of atoms into grain boundaries and grain boundary densification are suggested.<p>Funding Agencies|COST Action|MP0804|Linkoping University.</p><p>The previous status of this article was <em>Manuscript</em> and the working title was <em>Atomistic mechanisms leading to adatom insertion into grain boundaries and stress generation in physically vapor deposited films</em>.</p

Theoretical and experimental study of metastable solid solutions and phase stability within the immiscible Ag-Mo binary system

“…42 This is consistent with the notion of limited atomic mobility encountered during the growth of refractory metals close-to-room temperature as previously discussed. 3,36,37 With increasing Ag content in the films the effective mobility of film forming species increases (as Ag exhibits higher atomic mobility than Mo at room temperature) 37,39,40 resulting in a denser microstructure which is less prone to impurity incorporation. The incorporation of O and C species in the Morich grains is excluded due to the lack of oxide or carbide signature in the corresponding Mo 3d XPS spectra (not shown here).…”

“…Mo films grown at conditions very similar to those employed in the present study, have been found to be under biaxial tensile stress while exhibiting marginal expansion of the lattice in the out-of-plane direction. 36 This is because at conditions of limited atomic mobility, e.g., at close-to-room-temperature Mo deposition, underdense grain boundaries form which cause attraction between neighboring grains and thereby result in tensile stress generation. 37 Concurrently, Ar + ions are backscattered from the Mo target and impinge on the surface of the growing film as energetic neutrals creating point defects and a hydrostatic stress contribution; the latter counteract the effect of the tensile stresses leading to a small lattice dilation along the growth direction.…”

“…37 Concurrently, Ar + ions are backscattered from the Mo target and impinge on the surface of the growing film as energetic neutrals creating point defects and a hydrostatic stress contribution; the latter counteract the effect of the tensile stresses leading to a small lattice dilation along the growth direction. 36,38 In contrast to Mo, growth of Ag near room temperature results in high atomic mobility. At these conditions, compressive stress builds up during growth as adatoms diffuse into the grain boundaries driven by a chemical potential difference between the surface 13 that is supersaturated with adatoms and the grain boundary.…”

Cohesize zone‐based modeling of nano‐coating layers for the purpose of establishing process signatures

“…A homogeneous compressive residual stress σ * 11 in horizontal direction is considered within the coating due to atom diffusion into grain boundaries during the coating deposition [46]. In HPPMS coating deposition, compressive residual stresses represent a well-known phenomenon which might affect the coating's damage resistance.…”

Atomistic view on thin film nucleation and growth by using highly ionized and pulsed vapour fluxes

“…It should be brought to reader's attention that parts of sections 3, 4 are built upon results presented in two recently published works by Magnfält et al. [15,16] by putting these results in to a broader context as compared to the original reports.…”