In situstress evolution during and after sputter deposition of Al thin films

Abstract

The stress, growth, and morphology evolution of Al thin films up to 300 nm thick, sputter deposited at a constant rate of 0.04 nm s(-1) onto thermally oxidized Si(100) substrates have been investigated for various sputter pressures in the range from 0.05 to 6 Pa. The stress evolution has been studied during and after the film deposition by means of in situ substrate curvature measurements using an optical two-beam deflection method. In order to obtain insight into the mechanisms of stress generation and relaxation, the microstructure of the films was investigated by scanning electron microscopy, focused-ion-beam microscopy, and atomic force microscopy. The stress evolution during the early stage of deposition of films is consistent with the Volmer-Weber growth mode known for metals with high adatom mobility. For thicker films, the compressive stress increases in the sputter pressure range of 0.05-0.5 Pa, whereas at even higher sputter pressures a transition from compressive to tensile stress takes place. This transition is correlated with a change from a relatively dense to a more porous microstructure characterized by decreasing mass density and increasing electrical resistivity with increasing sputter pressure. The dependence of the stress and microstructure on the sputter pressure can be consistently understood through a combination of the stress mechanisms for vapor and sputter deposited films proposed in the literature.

Influence of the Thickness of a Nanolayer Composite Coating on Values of Residual Stress and the Nature of Coating Wear

“…Furthermore, from the substrate and layers deposited earlier, the coating layer being deposited is subjected to compressive stress caused by the mechanical action of positively charged ions bombarding the surface, possessing high kinetic energy due to the negative potential on the substrate (σ comp ) [56,57]. The effect is similar to that of bead blasting on the surface, when compression along the normal of the surface of the substrate and the extension in its plane occur, which is inhibited by the subsurface layers of the substrate and the coating layers deposited earlier that create compressive stress in the surface layers.…”

Large-Area Anodized Alumina Nanopore Arrays Assisted by Soft Ultraviolet Nanoimprint Prepatterning

“…Random grains of Al (a few hundred nm in size) could be observed, which were present even before the imprinting steps and is a common occurrence in sputtered Al films. 30 The highly-aligned pores indeed testified the success of pattern transfer on the large area despite some local imperfections of the original film surface, which was further confirmed by the six-fold symmetry spots of the FFT image (inset of Fig. 4(a) …”

Influence of adsorption kinetics on stress evolution in magnetron-sputtered SiO2 and SiNx films

“…Stress data measured during the interrupts of SiO 2 and SiN x films were fitted according to Eqs. (5) and (10). The fitting results are shown in Fig.…”

“…There have been a lot of works focusing on the stress evolution during and after deposition of thin films. Stress relief when growth was interrupted exists in metal Fe, 1 Ag, 2,3 Cu, [4][5][6][7] Au, 8 Al, 9,10 and Sn 11 films. And stress reversibility was observed in polycrystalline Fe, 1 Ag, 3 and Cu 6 films.…”